Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Zinc nanoparticles applied in the production of zinc–air batteries provide the highest specific energy among various metal–air combinations used in batteries in practice. Recent technical advances provide an opportunity to successfully solve the problems experienced during the early development of batteries of this type. For example, there is a major limitation in recharging cycles due to the massive formation of zinc oxide. In the present work, a reduction process is proposed on the basis of the use of alcohol solvent by applying microwave in-liquid plasma. The occurrence of reduction was confirmed by calculating the chemical potential of ethanol and methanol as well as spectra of plasma emission in the temperature range 1500–2000 K. Characterization of synthesized nanoparticles was carried out by energy-dispersive X-ray spectrometry and transmission electron microscopy.

DOI： 10.1007/s10891-021-02426-2

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Other Link： https://link.springer.com/article/10.1007/s10891-021-02426-2/fulltext.html

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Institute of Energy  

In this study, dielectric barrier discharge (DBD) was used to decompose methylene blue (MB) adsorbed on pellet-shaped zeolite, and zeolite was reused as an adsorbent. The DBD treatment was performed in air under atmospheric pressure. The effect of plasma treatment on the zeolite structure was investigated. The effect of DBD treatment was evaluated by the amount of MB adsorbed on the zeolite and the Total organic carbon (TOC) of the solution in the repeated adsorption test. When the plasma-treated zeolite was added to pure water, some substances desorbed from the zeolite, and as a result of NMR analysis, it was found that the substance does not have a benzene ring structure. The results showed that the methylene blue adsorbed on the zeolite was decomposed into a low molecule without a benzene ring by the DBD treatment, and it was desorbed during the next adsorption cycle, so that the adsorption site was recovered while maintaining the structure of the zeolite.

DOI： 10.3775/jie.100.97

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST ENERGY  

© 2020 Japan Institute of Energy. All rights reserved. One-step ammonia synthesis under ordinary temperature and pressure has been attempted by introducing a nitrogen source (pure nitrogen gas or air) to hydrogen production reaction field of in-liquid plasma. As a result of the experiment, it was confirmed that ammonia can be synthesized by this method. However, the amount of ammonia synthesized was small. Most of the produced hydrogen is as pure. Also, the introduced nitrogen source is almost released outside of the reactor. This indicates low ammonia selectivity, study is required to improve the selectivity. The findings of this study are that the hydrogen production efficiency (HPE) and the C O balance of the raw materials affect the amount of ammonia synthesized. It was found that the higher HPE the better. A one to one ratio of C and O was found to be the optimal condition.

DOI： 10.3775/jie.99.94

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST ENERGY  

© 2020 Japan Institute of Energy. All rights reserved. In this study, hydrogen production by the in-liquid plasma methods reported thus far was compared, to find the optimal method and condition. Because the in-liquid plasma is a type of plasma generated within bubbles in a liquid, an ingredient with a small evaporation enthalpy (EE) is found to be more advantageous. In addition, it is necessary to select an ingredient with a high thermodynamic ideal efficiency (IE), as calculated using the enthalpy of the formation. The actual hydrogen production efficiency (HPE) of water (IE, 0.28 Nm3-H2/kWh; EE, 44 kJ/mol), methanol (IE, 1.26 Nm3-H2/kWh; EE, 38 kJ/mol), n-dodecane (IE, 2.99 Nm3-H2/kWh; EE, 62 kJ/mol), were found to be 0.02, 0.28, and 0.13 Nm3-H2/kWh, respectively. The highest HPE was obtained for the methanol decomposition, indicating that ingredients with low EE and high IE are advantageous for hydrogen production. Moreover, the HPE reduced because most of the energy of the plasma diffused to the surroundings. Therefore, it is essential to develop efficient heat recovery methods and heat insulation systems.

DOI： 10.3775/jie.99.104

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Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.35848/1347-4065/aba0d7

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Other Link： https://iopscience.iop.org/article/10.35848/1347-4065/aba0d7/pdf

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST ENERGY  

At present, the two main wastewater treatment methods are biological treatment and coagulation sedimentation treatment. However, wastewater discharged from dyeing factories cannot be adequately treated because it contains persistent organic substances. The purpose of this study is to develop a treatment for dye wastewater using plasma under atmospheric pressure. The decolorization processing characteristics were investigated using a methylene blue (MB) solution as a model for dye wastewater. The study revealed that an MB solution could be decolorized using plasma treatment, and the conversion rate was correlated to the MB concentration. The discharge method and liquid temperature affected the conversion of MB, and the conversion rates and energy efficiencies were compared for each condition. Additionally, flow-type plasma that took in air from the side of the reaction vessel could treat MB the most efficiently and could be stably operated for considerable time. This process may eventually be used to treat dye wastewater discharged from actual dyeing factories.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST ENERGY  

For future sustainable-energy development. H-2 is a promising fueL Cellulose suspensions can be decomposed by 27.12-MHz radio frequency in-liquid plasma to produce H-2. In-liquid plasma decomposition uses an electrolyte solution of Na2SO4 to improve the efficiency of H-2 production. H-2 is the main product generated by plasma breakdown of cellulose; however, small quantities of carbon monoxide, carbon dioxide, and other low-grade flammable gases are also produced. Plasma generation requires the electron emission which increase with collision of Na+ and SO42- ions onto a copper electrode. Therefore, size of plasma increases with the concentration of Na2SO4 which leads to an increase in the decomposition amount of cellulose. so the energy efficiency improved. In addition, to estimate OH radical concentration. H2O2 concentration in solution was measured. Since OH radicals are consumed for cellulose decomposition, the concentration of H2O2 in the cellulose suspension was very small.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

A method has been developed to improve the hydrogen production efficiency (HPE) by in-liquid plasma n-dodecane decomposition. A thin steam pipe is placed over the plasma electrode to recover the thermal energy emitted from the plasma to its surroundings. The steam generated by this energy is supplied to the vaporized n-dodecane around the edge of the plasma to cause a steam reforming reaction (SRR). Water pyrolysis is suppressed by not supplying the steam directly to the plasma. A large amount of CO and a small amount of CO2 were detected in the produced gas. This indicates that a strong SRR has occurred. The HPE obtained by this method is 0.28 Nm(3)/kWh, which is two times greater than those obtained by previous methods, and similar to or greater than the yield of water electrolysis. This result is a major advance in the field of plasma heavy hydrocarbon decomposition aimed at hydrogen production. HPE is expected to be further improved by simply increasing the input power, due to synergy between the heat recovery effect of the steam pipe and the bubble stabilization effect. This indicates that this method has a high potential. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijhydene.2019.04.270

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Language：English   Publishing type：Research paper (international conference proceedings)  

A relationship between diamond synthesis and hydrogen production in in-liquid plasma method have been investigated. Approximately 60% energy can be recovered by collecting hydrogen gas made by ingredient solution decomposition. The relationship is trade-off. When higher energy is used to maintain the substrate temperature, the hydrogen production rate gets faster, but the diamond synthesis rate gets slower. To increase diamond synthesis rate, a method should be established which maintains the substrate temperature by lower energy and generates less hydrogen gas.

DOI： 10.4028/www.scientific.net/KEM.825.77

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© 2019 Trans Tech Publications Ltd, Switzerland This study was performed to improve the adhesiveness of a diamond-like carbon (DLC, a-C:H) layer film with an a-SiC interlayer. In previous studies, an a-SiC/DLC layer film was formed and changes in the DLC film structure and hardness caused by the thickness of the a-SiC layer were examined. After the a-SiC interlayer thickness increased and the G-peak position shifted to a lower frequency, the peak began shifting to higher frequencies. The G-peak position reached a minimum frequency at a film thickness of approximately 0.3 µm. In contrast, as the thickness of the a-SiC interlayer increased, the FWHM of the G-peak position increased almost monotonically and the number of sp3 bonds also increased. As the interlayer thickness increased, the hydrogen content in the DLC film increased, and then began decreasing, with the interlayer film thickness exhibiting a local maximum at approximately 0.3 µm. As for the DLC film hardness, a correlation between the hydrogen content and half width of the G-peak position was observed. When the hydrogen content was ≤40 at%, a positive correlation with the FWHM (G) was observed, and when the hydrogen content was 40 at% or above, a negative correlation with FWHM (G) was found. The adhesiveness of the DLC film and substrate was improved by forming an a-SiC thin film as an interlayer. The effects of the a-SiC thin film on DLC film quality were determined.

DOI： 10.4028/www.scientific.net/KEM.825.99

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Language：English   Publishing type：Research paper (international conference proceedings)  

Diamond crystals are successfully synthesized by irradiating DC arc plasma jet to the substrate set in a methanol solution. It is the important procedure to preheat the substrate by inert Ar plasma jet before introducing the methanol solution gas to the plasma jet gun. The effects of two experimental conditions, the incident power and the substrates, are investigated. In the case of the Si substrate, cubic crystalline diamond grains of same size are synthesized at the plasma power of 470W. High speed hetero epitaxy is expected by using this method. In the case of the tungsten carbide substrate, diamond crystals and carbon nanotubes are simultaneously synthesized at the plasma power of 260W. The catalytic effect of Co binder in the substrate may cause the chemical reaction of the nanotube synthesis.

DOI： 10.4028/www.scientific.net/KEM.825.71

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST ENERGY  

A lignin solution in methanol was treated with in-liquid plasma at 27.12 MHz radio frequency to produce H-2 and aromatic monomers. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analyses were performed to characterize the produced gases and degradation products contained in the solution. GC analysis identified H-2, CO, CH4, C2H2, CO2, and C2H4 in the sample. GC-MS analysis identified several products, including benzene. toluene, and phenol The quantity of each of these products was determined. These results indicated that the bonds around the benzene ring were broken in the plasma and reacted with OH radicals and CH3 radicals from methanol.

DOI： 10.3775/jie.97.171

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Publisher：IOP Publishing  

DOI： 10.7567/jjap.57.07le05

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Language：Japanese  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier Ltd  

To enhance hydrogen production efficiency by in-liquid plasma, the method inserting catalytic metal into in-liquid plasma reaction field was considered. To retain a bubble at the tip of in-liquid plasma electrode, a plate is fixed over the electrode. That plate and electrode are composed of a catalytic metal. Methanol is decomposed by in-liquid plasma, and the gas generation rate and composition rate are measured. The gas is composed of 67% H2, 30% CO, and 3% other. This rate is independent of the material of the electrode or plate. The plate enhances the hydrogen production rate. When the plate and electrode are composed of Ni (0.37 Nm3/kWh), the maximum hydrogen production rate is obtained.

DOI： 10.1016/j.ijhydene.2018.01.060

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Begell House Inc.  

In this study, decomposition of methane hydrate using an argon plasma jet was investigated in the pressure range of 0.1MPa to 2.0MPa. The plasma was successfully generated under high-pressure conditions, which is difficult to achieve when using the conventional radio frequency plasma in-liquid method. From the emission spectrometer analysis, excitation temperature of the argon plasma jet was found to decreases as the pressure increases, while conversely, the rotational temperature of OH increases. During the plasma irradiation process, the required basic reactions for methane hydrate decomposition, that is, methane hydrate dissociation, steam methane reforming, and methane cracking reaction were not fully satisfied due to an insignificant amount of methane that did not react. The gas chromatography analysis confirmed that only the methane cracking reaction has occurred to generate hydrogen and carbon, due to the absence of acetylene and ethylene as byproducts. In comparison with the other basic reactions of methane hydrate decomposition, the steam methane reforming reaction became dominant in converting methane into hydrogen.

DOI： 10.1615/ihtc16.nee.023225

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：CENTRE ADVANCED RESEARCH ENERGY-CARE  

Hydrogen shows great promise for being such a solution for providing sustainable energy while at the same time protecting the environment from greenhouse gases (GHGs). A 27.12 MHz RF plasma in liquid was used to decompose biomass-derived cellulose suspension for hydrogen production. At 1.0 M of sodium hydroxide, the result showed the highest hydrogen yield and the lowest greenhouse gases yield. An increase in molar concentration resulted in an increase of hydrogen production rate. On the other hand, it is noted that regardless of molar concentration, the hydrogen production rate significantly dropped with residence time.

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Language：English   Publisher：Institute for Ultrasonic Elecronics  

DOI： 10.24492/use.38.0_2p4-7

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Institute of Energy  

There is an imperative need to explore new technologies for hydrogen energy production without sacrificing life and environment. A 27.12 MHz radio-frequency plasma in liquid was used to decompose cellulose suspension for hydrogen production. The experiment was conducted to investigate the effects of sodium hydroxide and ultrasonic irradiation pretreatment. Molar concentration of sodium hydroxide was varied to 0.001 M, 0.01 M and 0.1 M and ultrasonic irradiation time was varied between 15 and 60 minutes in order to observe the hydrogen production rate and hydrogen yield. Hydrogen production had no significant enhancement at lower than 0.01 M sodium hydroxide. On the other hand, the hydrogen production rate increased dramatically to 23.0 μmol/s at 0.1 M sodium hydroxide. Typical optical emission spectrum of 0.001 M sodium hydroxide solution showed t hat radical species including OH (281.1 nm), Hβ (486 nm), Hα (656.3 nm) and O (777 and 845 nm) were generated which are very beneficial in attacking and decomposing organic molecules for hydrogen production. The highest production rate was obtained at 30 minutes of pretreatment. A longer than 3 0 minutes pretreatment with ultrasonic irradiation reduced the hydrogen production rate. Thus, ultrasonic irradiation pretreatment between 15 and 30 minutes was the potential condition for hydrogen production without sacrificing greenhouse gases effect.

DOI： 10.3775/jie.96.451

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE INC  

The purpose of this study is to synthesize diamond onto Si, Cu, and Fe (SUS632J2) substrates and to analyze the effect of carbon diffusion on their surfaces. Diamond was synthesized using the in-liquid microwave plasma chemical vapor deposition (IL-MPCVD) as a novel method for synthesizing diamond on various base materials. The IL-MPCVD method is superior one due to its efficiency in terms of cost, space and speed as compared to a conventional gas phase microwave plasma CVD (MPCVD). Microwaves of 2.45 GHz generated plasma in a solution which was comprised of methanol: ethanol (M:E= 97:3). Evaluation of deposited diamond films was done by a Scanning Electron Microscope (SEM) and Raman spectroscopy. Results shows that the IL-MPCVD method can form diamond films on Cu, Si and Fe substrates. The minimum time of film formation of Cu, Si and Fe are 2.5, 3.5 and 5 min, respectively. The material that forms carbide layers such as Si is a better substrate to form diamond film by the IL-MPCVD than other metal substrates such as Cu and Fe. Synthesizing diamond directly on the Fe substrate results in poor quality layers. The effect of carbon diffusion influences diamond film nucleation and diamond growth. In order to alleviate the carbon diffusion and improve the quality of the diamond film on the Fe substrate, Si has been sputtered on the Fe substrate as an interlayer. It is found that the diamond film can be formed on a Fe substrate using a Si interlayer and that heat treatment and thickening the interlayer improve its quality. (C) 2017 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.precisioneng.2017.04.003

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Institute of Energy  

The aim of this study was to investigate the effect of gas flow rate on the gas production rate from n-dodecane using steam reforming in-liquid plasma. A steam reforming of n-dodecane was carried out within the reactor vessel which was connected to a waveguide, an aluminum rectangular tubes that guides the propagation of electromagnetic waves with minimum loss of energy. The liquid medium used for plasma generation was n-dodecane (commercial reagent). The tip of a single electrode was positioned in the bottom center of the reactor vessel for plasma formation. The produced gas flowed through an aspirator and was trapped and collected in a water filled container. The gas production rate was measured and its compositions were analyzed using a gas chromatograph. The gas production rate by plasma with steam feeding was 1.4 times greater than that by plasma without steam feeding. The hydrogen content of the gas produced ranged from 73% to 82%. The maximum energy efficiency, as indicated by the ratio of the enthalpy difference of the chemical reactions to the input energy, was approximately 12%. The maximum hydrogen generation efficiency obtained from experiments was up to 59% higher than the efficiency of hydrogen production from electrolysis of alkaline solutions as reported in literatures. The energy payback ratio of hydrogen (EPRH2)was also calculated in order to obtain the hydrogen production efficiency.

DOI： 10.3775/jie.96.86

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In this study, decomposition of methane hydrate using argon plasma jet investigated in the pressure range of 0.1MPa to 2.0MPa. The plasma generated under the high-pressure condition, which is difficult to achieve when using radio frequency (RF) plasma in the liquid method. By using emission spectrometer analysis, the excitation temperature is found to increase as the gas pressure increases, whereas, it decreases as the argon flow rate increases. During the process of plasma irradiation, the required essential reactions for methane hydrate decomposition, such as methane hydrate dissociation (MHD), steam methane reforming (SMR), and methane cracking reaction (MCR) were not completely satisfied due to an insignificant amount of methane. The gas chromatography analysis confirmed that the methane cracking reaction (MCR) was only occurred to generate hydrogen and the C(s), due to the absence of C2H2 and C2H4 as the byproducts. In comparison with the other primary reactions of methane hydrate decomposition, steam methane reforming reaction became dominant in converting methane into hydrogen. Although the hydrogen production efficiency is less than that of radio frequency plasma in liquid, the reduction of CO2 by the thermal decomposition of Teflon from CO making it possible is considered as an advanced promising technique in the future.

DOI： 10.18517/ijaseit.7.6.2638

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Language：English   Publishing type：Research paper (scientific journal)  

J-GLOBAL

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/jsmecs.2017.55.K0704

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© 2017 Trans Tech Publications, Switzerland. Currently, novel method to synthesize diamond film on material substrate called as in-liquid microwave plasma CVD (IL-MPCVD) has been achieved. It has been studied and improved in addition expected as new method instead of conventional gas phase microwave plasma CVD (MPCVD). The purpose of this study is to synthesize single crystal diamond using IL-MPCVD in high speed deposition. The experimental conditions, methanol was poured in to the reactor. Each of diamond particles (100) and (111) was embedded on the stainless steel substrates (SUS632J2). It was mounted to the substrate holder of in-liquid plasma equipment and installed on the top cover. The distance between the tip of the electrode and the substrate was kept to 1.5mm. A microwave of 2.45GHz was irradiated into the quartz glass tube reactor from the rectangular cavity resonator with 4 mm diameter tungsten electrode and the plasma was generated at its tip. The microwave was adjusted in appropriate power to maintain a certain substrate temperature. Diamond films were evaluated by Raman spectroscopy, Scanning Electron Microscope (SEM) and Laser Microscope (LM). As a result, the best orientation for epitaxial growth was found to be (100) which have film growth gradually and smooth surface. Whereas (111) face has polycrystalline film with irregularity growth and rough surface. The remaining H and C after CO synthesis satisfying H/C>20 is necessary to synthesized diamond using IL-MPCVD. The deposition rate was about 32m/h when both single crystal and polycrystalline diamond film were synthesized.

DOI： 10.4028/www.scientific.net/KEM.749.211

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Institute of Energy  

Metal air battery attracts attention as an automobile battery, because of its high energy density. In order to reuse the battery, it is necessary to undertake reduction of metal oxide which is generated at the cathode without large environment load. We conducted the reduction of ZnO powder by radio-frequency dielectric heating. The ZnO powder and a reducing agent of organic liquid is put into a reaction vessel, and the tip of the electrode inserted from the top of the vessel is in contact with the surface of the powder. By measuring the spectrum of the blackbody radiation, the temperature was found to be approximately 2000 K. The reduction amount of ZnO increased remarkably when 0.7 to 1.4 mL of methanol was added as a reduction agent to 2.0 g ZnO powder, with a maximum of 27.6 mg at 1.1 mL reached. The reduction amount was smaller when ethanol, acetone, furfural, cyclohexane or dodecane were added as a reduction agent. The maximum energy efficiency is 3.3% without taking the reaction energy of the reduction agent into consideration, whereas it becomes 1.0% when taking it into consideration.

DOI： 10.3775/jie.96.357

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© 2017 Trans Tech Publications, Switzerland. High-speed synthesis of the carbon nanotubes in liquid is introduced. The conventional method for synthesizing carbon nanotubes is generally known as gas-phase chemical-vapor deposition (CVD). With that method, carbon nanotubes of high purity can be synthesized, but the synthesis rate is low. Even though the synthesized carbon nanotubes are excellent materials, they cannot be used in large quantities. Accordingly, in this study, single-wall carbon nanotubes (SWCNTs) are synthesized by "in-liquid" CVD. Since the molecular density of a liquid is much higher than that of a gas and the liquid has a cooling effect, performing CVD in a liquid can provide a high-speed growth rate of CNTs on substrate materials. A silicon substrate on which cobalt micro particles are deposited as the catalyst was used. Electrical-resistance heating was used for growing carbon nanotubes in pure ethanol. The synthesized nanotubes were analyzed by scanning electron microscope, transmission electron microscope, and Raman spectroscopy. The results of these analyses indicate that SWCNTs were successfully synthesized over a wide area of the substrate surface. By investigating the synthesized carbon nanotubes under varied experimental conditions (such as pressure and substrate surface roughness), it is shown that surface roughness of the substrate and the bubble behavior are related to the synthesis mechanism of the CNTs.

DOI： 10.4028/www.scientific.net/KEM.749.217

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Language：English   Publishing type：Research paper (international conference proceedings)  

© 2017 Trans Tech Publications, Switzerland. Diamond-like-carbon (DLC) films are promising as coating materials. Ion plating, an excellent method in terms of adhesiveness, step coverage, and deposition rate, can form not only pure metal films but also oxide films, nitride films, and carbonized films. In this study, which aimed to form a DLC film with good adhesiveness and a diamond crystal structure, a DLC film, with a SiC interlayer formed by ion plating with introduction of tetramethylsilane (TMS), was formed. It was experimentally revealed that as the interlayer thickness increases, the crystal structure in the DLC film becomes more diamond rich, and the adhesiveness of the DLC film and substrate is thereby improved.

DOI： 10.4028/www.scientific.net/KEM.749.70

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Language：Japanese   Publisher：公益社団法人 精密工学会  

本研究の目的は高純度単層カーボンナノチューブを高速形成することである．気相よりも分子密度の高い液相における液中熱化学気相蒸着(CVD)法での合成について調査し考察した．膜厚と合成温度の関係，触媒金属の種類によるCNT合成影響，溶液の構成元素数の違いによる影響を考察した．膜厚と温度の関係，適切な触媒金属，液中CVD法でのCNT合成手法の確立がなされた．

DOI： 10.11522/pscjspe.2017A.0_433

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

The use of ultrasonic welding in water to decompose cellulose placed in water was examined experimentally. Filter paper was used as the decomposition material with a horn-type transducer 19.5 kHz adopted as the ultrasonic welding power source. The frictional heat at the point where the surface of the tip of the ultrasonic horn contacts the filter paper decomposes the cellulose in the filter paper into 5-hydroxymethylfurfural (5-HMF), furfural, and oligosaccharide through hydrolysis and thermolysis that occurs in the welding process. (C) 2016 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.55.07KE02

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：実教出版  

CiNii Books

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>In this study, the synthesis of single-wall carbon nanotubes (SWCNT) using in-liquid CVD method is attempted. Si substrate on which Co micro particles are deposited as the catalyst is used. Electrical resistance heating method is used for glowing carbon nanotubes in pure ethanol. The synthesized materials are analyzed by scanning electron microscope, transmission electron microscope and Raman spectroscopy. As a result, the synthesis of SWCNT was successful on a wide area of the substrate surface. By investigating the synthesized carbon nanotubes changing experimental conditions such as pressure, substrate surface roughness and others, it is cleared that surface roughness of the substrate and the bubble behavior are related to the synthetic mechanism of carbon nanotubes.</p>

DOI： 10.1299/jsmeted.2016.G114

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/jsmecs.2016.54._417-1_

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>The decomposition of cellulose suspension for hydrogen production by using a 27.12MHz in-liquid plasma is carried out at atmospheric pressure. Various types of electrolyte, such as 1 mol/dm³ H₂SO₄, 1 mol/dm³ NaOH and 0.333 mol/dm³ Na₂SO₄, are used and the gas production rate are compared. An employing 1 mol/dm³ NaOH for decomposition process indicated that the gas production rate was 7 times higher than that of decomposition of cellulose in pure water. When cellulose content is 20 wt%, the hydrogen ratio in the produced gas is approximately 60%. EPR (energy payback ratio) in which measured for economical production of hydrogen is the highest When 1 mol/dm³ NaOH is used as an electrolyte for decomposition process.</p>

DOI： 10.1299/jsmeted.2016.G122

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Institute of Energy  

Hydrogen energy is the most promising source of sustainable energy under development. The decomposition of cellulose suspension for hydrogen production by using a 27.12 MHz in-liquid plasma was carried out at atmospheric pressure. Various types of reagents, such as 1 mol/dm3 H2SO4, 1 mol/dm3 NaOH and 0.333 mol/dm3 Na2SO4, were used and compared as to the rate of gas production. Cellulose dispersed in acid liquids is decomposed indirectly by active radicals by the plasma. The highest hydrogen production rate was obtained by employing 1 mol/dm3 NaOH. The gasification rate of cellulose suspension was determined from the increase of C atoms in the product gas. When 1 mol/dm3 NaOH was used, the rate was 7 times greater than that for pure water. It was found that carbon atoms in the product gas is indicative of the decomposition rate of the cellulose suspension.

DOI： 10.3775/jie.95.1105

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<p>This research investigates the direct phenol production from toluene by dielectric-barrier discharge (DBD) plasma in a mixture gas of argon and water vapor. Two kinds of experiment were conducted. The first experiment was by irradiating the surface of liquid toluene with DBD plasma jet, and the second one was by generating DBD plasma in a bottle of toluene into which the mixture gas was flowing. The maximum phenol yields at the first and second experiment were 0.8×10^-3% and 3.2×10^-3%, respectively. The phenol yield at the first experiment increased with decrease of input power for the DBD. The phenol yield at the second experiment took the maximum when the water for making the mixture gas by bubbling was the room temperature.</p>

DOI： 10.1299/jsmeted.2016.G123

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

This research involves two in-liquid plasma methods of methane hydrate decomposition, one using radio frequency wave (RF) irradiation and the other microwave radiation (MW). The ultimate goal of this research is to develop a practical process for decomposition of methane hydrate directly at the subsea site for fuel gas production. The mechanism for methane hydrate decomposition begins with the dissociation process of methane hydrate formed by CH4 and water. The process continues with the simultaneously occurring steam methane reforming process and methane cracking reaction, during which the methane hydrate is decomposed releasing CH4 into H-2, CO and other by-products. It was found that methane hydrate can be decomposed with a faster rate of CH4 release using microwave irradiation over that using radio frequency irradiation. However, the radio frequency plasma method produces hydrogen with a purity of 63.1% and a CH conversion ratio of 99.1%, which is higher than using microwave plasma method which produces hydrogen with a purity of 42.1% and CH4 conversion ratio of 85.5%. (C) 2015 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.applthermaleng.2015.06.074

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

This research involves two in-liquid plasma methods of methane hydrate decomposition, one using radio frequency wave (RF) irradiation and the other microwave radiation (MW). The ultimate goal of this research is to develop a practical process for decomposition of methane hydrate directly at the subsea site for fuel gas production. The mechanism for methane hydrate decomposition begins with the dissociation process of methane hydrate formed by CH4 and water. The process continues with the simultaneously occurring steam methane reforming process and methane cracking reaction, during which the methane hydrate is decomposed releasing CH4 into H-2, CO and other by-products. It was found that methane hydrate can be decomposed with a faster rate of CH4 release using microwave irradiation over that using radio frequency irradiation. However, the radio frequency plasma method produces hydrogen with a purity of 63.1% and a CH conversion ratio of 99.1%, which is higher than using microwave plasma method which produces hydrogen with a purity of 42.1% and CH4 conversion ratio of 85.5%. (C) 2015 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.applthermaleng.2015.06.074

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Hydrogen is a very attractive source of highly efficient and environmentally friendly energy. Investigation into hydrogen production from glucose decomposition by 27.12 MHz radio-frequency in-liquid plasma with and without ultrasonic vibrations was carried out utilizing 29 kHz and 1.6 MHz ultrasonic transducers to determine the effects of agitation and acoustic streaming. In-liquid plasma is generated inside a bubble, resulting in a high temperature chemical reaction field within the liquid which is then irradiated by ultrasonic vibration. The dependence of hydrogen production rate, hydrogen yield, hydrogen purity and hydrogen production efficiency on the types of ultrasonic vibration applied was investigated. Higher intensities of active C atoms species were observed in the emission spectrum of RF in-liquid plasma when irradiated with ultrasonic vibration and it is believed that these species function as precursors or intermediaries for other components in the gas product. Hydrogen production rate was enhanced by 30% when RF in-liquid plasma was irradiated by the 1.6 MHz piezoelectric transducer. The highest hydrogen yield was 72% for RF in-liquid plasma with the 29 kHz ultrasonic transducer at an initial concentration 1.0%. The hydrogen purity was enhanced by 5% for the highest initial concentration when applying the 29 kHz ultrasonic transducer to the RF in-liquid plasma. Thus the acoustic streaming effect by 1.6 MHz piezoelectric vibration enhanced the hydrogen production rate, while on the other hand, the agitation effect by 29 kHz ultrasonic vibration enhanced hydrogen yield and hydrogen purity. Though the hydrogen production efficiency of RF in-liquid plasma with ultrasonic vibration applied was lower overall when compared to that without ultrasonic vibration except for decomposition of glucose 20 wt% by RF in-liquid plasma with 1.6 MHz ultrasonic transducer which was 7% higher than that without ultrasonic vibrations, this remains a process that could be considered as a promising future technique for hydrogen production. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijhydene.2015.04.152

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Hydrogen is a very attractive source of highly efficient and environmentally friendly energy. Investigation into hydrogen production from glucose decomposition by 27.12 MHz radio-frequency in-liquid plasma with and without ultrasonic vibrations was carried out utilizing 29 kHz and 1.6 MHz ultrasonic transducers to determine the effects of agitation and acoustic streaming. In-liquid plasma is generated inside a bubble, resulting in a high temperature chemical reaction field within the liquid which is then irradiated by ultrasonic vibration. The dependence of hydrogen production rate, hydrogen yield, hydrogen purity and hydrogen production efficiency on the types of ultrasonic vibration applied was investigated. Higher intensities of active C atoms species were observed in the emission spectrum of RF in-liquid plasma when irradiated with ultrasonic vibration and it is believed that these species function as precursors or intermediaries for other components in the gas product. Hydrogen production rate was enhanced by 30% when RF in-liquid plasma was irradiated by the 1.6 MHz piezoelectric transducer. The highest hydrogen yield was 72% for RF in-liquid plasma with the 29 kHz ultrasonic transducer at an initial concentration 1.0%. The hydrogen purity was enhanced by 5% for the highest initial concentration when applying the 29 kHz ultrasonic transducer to the RF in-liquid plasma. Thus the acoustic streaming effect by 1.6 MHz piezoelectric vibration enhanced the hydrogen production rate, while on the other hand, the agitation effect by 29 kHz ultrasonic vibration enhanced hydrogen yield and hydrogen purity. Though the hydrogen production efficiency of RF in-liquid plasma with ultrasonic vibration applied was lower overall when compared to that without ultrasonic vibration except for decomposition of glucose 20 wt% by RF in-liquid plasma with 1.6 MHz ultrasonic transducer which was 7% higher than that without ultrasonic vibrations, this remains a process that could be considered as a promising future technique for hydrogen production. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijhydene.2015.04.152

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Metal air-batteries with high-energy density are expected to be increasingly applied in electric vehicles. This will require a method of recycling air batteries, and reduction of metal oxide by generating plasma in liquid has been proposed as a possible method. Microwave-induced plasma is generated in ethanol as a reducing agent in which zinc oxide is dispersed. Analysis by energy-dispersive x-ray spectrometry (EDS) and x-ray diffraction (XRD) reveals the reduction of zinc oxide. According to images by transmission electron microscopy (TEM), cubic and hexagonal metallic zinc particles are formed in sizes of 30 to 200 nm. Additionally, spherical fiber flocculates approximately 180 nm in diameter are present.

DOI： 10.1088/2053-1591/2/2/025004

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Metal air-batteries with high-energy density are expected to be increasingly applied in electric vehicles. This will require a method of recycling air batteries, and reduction of metal oxide by generating plasma in liquid has been proposed as a possible method. Microwave-induced plasma is generated in ethanol as a reducing agent in which zinc oxide is dispersed. Analysis by energy-dispersive x-ray spectrometry (EDS) and x-ray diffraction (XRD) reveals the reduction of zinc oxide. According to images by transmission electron microscopy (TEM), cubic and hexagonal metallic zinc particles are formed in sizes of 30 to 200 nm. Additionally, spherical fiber flocculates approximately 180 nm in diameter are present.

DOI： 10.1088/2053-1591/2/2/025004

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Language：English   Publisher：Institute for Ultrasonic Elecronics  

DOI： 10.24492/use.36.0__2P4-13-1_

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/jsmecs.2015.53._1114-1_

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/jsmecs.2015.53._1113-1_

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

The objective of this research is to investigate the possibility of producing phenol directly from a mixture of toluene and water by in-liquid plasma and to understand the process of converting toluene into phenol. Radio frequency (RF) in-liquid plasma was used to synthesize phenol from toluene. In addition, GAUSSIAN was used to predict the process of conversion and other products. In the proposed method of phenol production, OH radicals produced from water molecules by in-liquid plasma play a major role during the process of direct chemical reaction with toluene. The experimental results showed that phenol can be directly produced from toluene, and benzyl alcohol and formaldehyde were synthesized in the process.

DOI： 10.1299/jsmeted.2015._C233-1_

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Publishing type：Part of collection (book)  

© Springer International Publishing Switzerland 2014. Clathrate hydrates, which were formed from methane and cyclopentane, were decomposed by plasma at atmospheric pressure. Methane hydrate was synthesized by injecting methane into shaved ice in the reactor at a pressure of 7 MPa and a temperature of 0 °C. In addition, cyclopentane hydrate was formed by adding surfactant into cyclopentane-water emulsion at 0.1 MPa and a temperature of 0 °C. The process of plasma decomposition of clathrate hydrates has been carried out by irradiating high frequency plasma at the tip of the electrode in clathrate hydrates. 2.45 GHz MW oven and 27.12 MHz RF irradiation were used. This study results gas production that its content identified by gas chromatograph. High purity of hydrogen would be extracted from clathrate hydrate using the in-liquid plasma method.

DOI： 10.1007/978-3-319-07896-0_30

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Institute of Energy  

The purpose of this study is to efficiently produce hydrogen gas from saccharide using 27.12 MHz radiofrequency (RF) in-liquid plasma with and without ultrasonic irradiation. The experiments were conducted adopting two different ultrasonic frequencies, one from a 29 kHz horn-type ultrasonic transducer and the other from a 1.6 MHz piezoelectric transducer. The glucose solution and cellulose suspension concentrations were varied from 0.5 wt% to 50 wt% and 0.5 wt% to 20 wt% respectively. Hydrogen gas was then produced by the decomposition of the glucose solution and cellulose suspension by RF in-liquid plasma with and without ultrasonic irradiation. The hydrogen production rate from glucose solution with ultrasonic irradiation applied was greater than that without ultrasonic irradiation. However, no hydrogen production rate enhancement was observed from decomposition of cellulose suspension with ultrasonic irradiation applied. Ultrasonic atomization and agitation enhanced the chemical reaction of nonvolatile glucose in in-liquid plasma. The increase of the gas production rate was caused by the direct decomposition of the glucose by the plasma due to the atomized glucose molecules being fed into the plasma in a bubble. In addition, by using a high-speed camera, it was clarified that acoustic streaming occurred when a 1.6 MHz piezoelectric transducer was used in the experiment.

DOI： 10.3775/jie.93.1207

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Hydrogen is more attractive as an efficient and environmental friendly source of energy. In order to study the effect of ultrasonic vibration on enhancing the production of hydrogen, 27.12 MHz radio-frequency (RF) in-liquid plasma was observed with and without ultrasonic vibration applied. Two types of ultrasonic transducers were used, a 29 kHz horn-type ultrasonic transducer and a 1.6 MHz piezoelectric transducer. In-liquid plasma is generated inside a bubble generated by evaporation of a liquid heated by plasma resulting in a high temperature chemical reaction field within the liquid to which ultrasonic vibrations were then applied to enhance the chemical reaction process. 120 ml of glucose solution was used as a biomass model. The solution varied from 0.5wt% to 20wt% of glucose in order to observe the hydrogen production rate, hydrogen yield and selectivity. The results indicated that the application of 1.6 MHz ultrasonic vibration to RF in-liquid plasma enhanced the hydrogen production rate by approximately 34% due to acoustic streaming. On the other hand, enhancements of 13% of hydrogen yield and 4.6% of hydrogen selectivity were indicated by the application of 29 kHz ultrasonic vibration to RF in-liquid plasma with. The reason is believed to be due to a mechanochemical effect. Hence, ultrasonic vibration synergized the production of hydrogen from glucose solution.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

A process for synthesis of nanoparticles using plasma in water generated by a radio frequency of 27.12 MHz is proposed. Tungsten oxide, silver, and gold nanoparticles were produced at 20 kPa through erosion of a metallic electrode exposed to plasma. Characterization of the produced nanoparticles was carried out by XRD, absorption spectrum, and TEM. The nanoparticle sizes were compared with those produced by a similar technique using plasma in liquid. (c) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jallcom.2013.05.032

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The electrical breakdown of microwave plasma in water was investigated between 1 and 30 kPa. The dependency of the ignition power for generating plasma on the size of coaxial electrode was measured. The ignition power decreases with a decrease of the diameter of the inner electrode. The behavior of microwave plasma in water was observed using a high-speed camera. The plasma ignites in a bubble generated by microwave heating. The model for calculating the electric field was created on the basis of the captured images of the bubble just before plasma ignition. The method presented can be used to visualize the electrical field distribution in the bubble. The electric field breakdown was calculated using the measured ignition power. The electric field breakdown of plasma in water is of the same order as gas phase plasma. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cap.2013.02.012

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Tungsten trioxide nanoparticles were synthesized from a tungsten wire by plasma generated in water by 2.45 GHz microwaves. The effect of synthesis pressure, power and wire diameter on the formation of nanoparticles and the production rate was investigated. The character of the produced nanoparticles was determined by XRD, absorption spectrum, TEM and particle size distribution. The method proposed in this paper allows control of the nanoparticle size and shape and the optical properties through pressure alone without any additives. In one specific experiment, spherical nanoparticles with a peak diameter of 7 nm were synthesized from a tungsten wire with a diameter of 1 mm by 200 W at 20 kPa at a high production rate of 4 mg/s. Whereas, rhombic cylindrical nanoparticles together with spherical nanoparticles were synthesized with a peak diameter of 13 nm at 101 kPa. In addition, plasma and bubble behavior was observed by high-speed camera. Use of a plate to control the updraft of the bubbles caused the gap between the plate and the coaxial electrode to remain consistently filled with bubbles, and plasma generation continued without pause. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jallcom.2013.01.137

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Language：Japanese   Publisher：社団法人プラズマ・核融合学会  

液中プラズマとは液体中の気泡中に温度数千Kのプラズマを発生させる技術である.この技術を使えば,油や廃液などの有機溶媒を直接プラズマで分解し,水素を取り出すことができる.日本は水素社会の到来に向けて,水素自動車を普及させるためにインフラを整備し,2015年までに100か所に水素ステーションの設置を計画している.廃棄物から安価な方法で水素を取り出し,内燃機関として利用することができれば,従来のエンジンを改良するだけで,水素自動車が実現できる.2011年,著者らは液中プラズマ技術で分解,回収された水素で,水素燃焼型自動車を動かす実験を行い,走行実験に成功した.この技術を応用すれば,日本近海に存在するメタンハイドレートを水素として回収することも可能となる.

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J-GLOBAL

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Language：Japanese   Publisher：化学工業社  

CiNii Books

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Language：Japanese  

CiNii Books

J-GLOBAL

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Methane hydrate, formed by injecting methane into 100 g of shaved ice at a pressure of 7 MPa and reactor temperature of 0 degrees C, was decomposed by applying 27.12 MHz radio frequency plasma in order to produce hydrogen. The process involved the stimulation of plasma in the methane hydrate with a variable input power at atmospheric pressure. It was observed that production of CH4 is optimal at a slow rate of CH4 release from the methane hydrate, as analyzed by in light of the steam methane reforming (SMR) and the methane cracking reaction (MCR) processes in accordance with the content of gas production. In comparison with the steam methane reforming (SMR), it was found that methane-cracking reaction (MCR) was dominant in conversion of CH4 into hydrogen. An H-2 content of 55% in gas production was obtained from conversion of 40% of CH4 at an input power of 150 W. The results clearly show that hydrogen can be directly produced from methane hydrate by the in-liquid plasma method. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijhydene.2012.07.099

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Language：Japanese   Publisher：化学工業社  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

The erosion of a conventional bare metallic electrode for generation of microwave plasma in liquid was investigated. The spectra of plasma, the surface temperature of the electrode and the erosion rate were measured by a spectroscope, a radiation thermometer and an analytical balance, respectively. The intensity of the spectral lines indicating the erosion of the metallic electrode and erosion rate depends upon the microwave power. To avoid metallic contamination, a coaxial electrode for generating microwave plasma on a dielectric material was developed. The metallic electrode is encased in an alumina closed tube. The side of the alumina closed tube is further covered with an open Teflon tube. It has been confirmed that the electric field is strongest at the point where the alumina closed tube, Teflon opened tube and liquid intersect as determined by the two-dimensional Finite-Difference Time-Domain (2D-FDTD) method. Synthesis of amorphous-carbon deposition in ethanol was conducted. The developed electrode enables synthesis with a smooth deposition. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.surfcoat.2011.09.045

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Nanoparticles are continuously synthesized from submerged magnesium, zinc, and silver rods 1-2 mm in diameter by microwave plasma in pure water at 20 kPa. Magnesium-hydroxide nanoplates shaped as triangles, truncated triangles or hexagons with 25-125 nm in size are synthesized with a production rate of 60 g h(-1). Zinc-oxide nanoparticles formed as sharp sticks with diameters of 50 nm and lengths of 150-200 nm are synthesized with a production rate of 14 g h(-1). Silver nanoparticles with a diameter of approximately 6 nm are synthesized with a production rate of 0.8 g h(-1). The excitation temperature is estimated by applying the Boltzmann plot method in assumption of local thermodynamic equilibrium. The excitation temperatures obtained from hydrogen, magnesium, and zinc lines are 3300 100 K, 4000 +/- 500K, and 3200 +/- 500 K, respectively. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matchemphys.2011.09.068

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Language：English   Publisher：IOP PUBLISHING LTD  

DOI： 10.1143/APEX.4.099201

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Language：English   Publisher：IOP PUBLISHING LTD  

DOI： 10.1143/APEX.4.099201

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

The purpose of this study is to clarify the mechanism of diamond synthesis using an in-liquid plasma chemical vapor deposition (CVD) method. We investigated the chemical reactions from a liquid mixture of methanol and ethanol (in-liquid plasma CVD) and a gas mixture of methane and hydrogen (gas-phase CVD). Carbon monoxide (CO) is firstly synthesized and then a chemical reaction using the remaining carbon (C) and hydrogen (H) is induced to synthesize a carbon substance. Residual H radicals act as an etchant removing the incompletely binding carbon atom that hinders diamond crystal growth. From spectroscopic measurements, CO peaks were clearly observed when the oxygen component is contained in the raw materials. From the experimental results of carbon deposits using various liquid and gas mixtures as the raw materials, we found that the region of the remaining H and C after CO synthesis satisfying H/C &gt;20 is necessary to synthesize diamonds using in-liquid plasma CVD method. The region of H/C &gt;20 in the Bachmann C-H-O diagram nearly agrees with the experimental results of synthesizing diamonds. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.diamond.2011.07.010

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

A radio frequency plasma was generated and maintained in water over a wide range of water conductivities (0.2-7000 mS m(-1)). The conductivity of water was changed by adding NaCl to it. The size of the plasma increased with conductivity. Although the intensity of the OH (A-X) line monotonically decreased with increasing conductivity, the generation of hydrogen peroxide and the degradation of methylene blue suggested that the number of generated OH radicals decreased with increasing conductivity in the range 0.2-80 mS m(-1) and increased in the range 80-7000 mS m(-1). Ultraviolet irradiation was found to enhance the degradation of methylene blue not only in pure water but also in high-conductivity water (similar or equal to 5000 mS m(-1)).

DOI： 10.1088/0963-0252/20/3/034016

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

The excitation temperature, electron density, temperature of OH, and behavior of bubbles generated by a 27.12 MHz in-liquid plasma are investigated in water under pressures ranging from 0.1 to 0.4 MPa. The excitation temperature decreases as the pressure increases and, conversely, the temperature of OH and the electron density increase. Since the plasma can be generated stably even under high-pressure conditions and the liquid provides a cooling effect, the electrode is not damaged by the heat. The bubbles generated from the tip of the electrode have a fixed relationship between their diameter and departure frequency. The in-liquid plasma can be stably generated even under high pressures and it maintains a high superheated state of a few thousand K. A boiling phenomenon in the in-liquid plasma uses the plasma itself as a heat source.

DOI： 10.1088/0963-0252/20/3/034012

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We analyzed the gas generated by a radio-frequency plasma in water and found that the ratio of oxygen to hydrogen in it was approximately 0.7-11%. Numerical simulations of the chemical reactions occurring inside and outside the bubble with increasing energy supply in the concentric volume in it were carried out. Thermal conduction and diffusion occurring inside and outside the bubble, and evaporation (condensation) and solution of gases at the surface were taken into consideration. After terminating the energy supply, we found that nearly all the oxygen within the bubble was consumed but that hydrogen remained, and that oxygen in the water produced from dissolved chemical species diffused into the bubble. Good agreement with experiment results was obtained for reducing the production rate of hydrogen and the oxygen-hydrogen ratio that occurred with a pressure increase. We found that in comparison with experimental results the hydrogen production rate was underestimated by approximately 35%.

DOI： 10.1088/0963-0252/20/3/034020

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

A radio frequency plasma was generated and maintained in water over a wide range of water conductivities (0.2-7000 mS m(-1)). The conductivity of water was changed by adding NaCl to it. The size of the plasma increased with conductivity. Although the intensity of the OH (A-X) line monotonically decreased with increasing conductivity, the generation of hydrogen peroxide and the degradation of methylene blue suggested that the number of generated OH radicals decreased with increasing conductivity in the range 0.2-80 mS m(-1) and increased in the range 80-7000 mS m(-1). Ultraviolet irradiation was found to enhance the degradation of methylene blue not only in pure water but also in high-conductivity water (similar or equal to 5000 mS m(-1)).

DOI： 10.1088/0963-0252/20/3/034016

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER  

Nanoparticles are synthesized efficiently from zinc electrode by microwave plasma in liquid. The nanoparticles synthesized from alcohol resulted in pure zinc particles in the shape of spheres or hexagonal cylinders with a production rate of 3.3 g/h, and energy consumption of 267 J/mg for 1 mg. Whereas the nanoparticles synthesized in pure water are composed of Zn and ZnO. The Zn reacts with water through heat or the passage of time to become ZnO, releasing hydrogen gas. An upper disk placed 1 mm away from the electrode along with the bubbles generated simultaneously with the plasma ignition plays a key role in the synthesis of nanoparticles. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matlet.2010.09.068

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER SOC MECHANICAL ENGINEERS  

The purpose of this research is to develop a process to use plasma decomposition of hydrocarbon liquids or clathrate hydrates in a microwave oven to produce fuel gas while simultaneously solidifying the carbon and synthesizing it into useful carbonized materials, such as CNTs or activated charcoal. Hydrogen gas with a purity of 60% to 80% can be extracted using a conventional microwave oven. This means that the energy efficiency of hydrogen production using this method is estimated to be approximately 50% of that by electrolysis of alkaline water and approximately 1% of that by the natural gas steam reforming method However, this process has the added benefit of producing solid carbon at the same time. This method can be applied to a wide variety of waste liquids, or hydrate. Surplus electrical energy could be used to process waste liquids from homes and factories, and the resulting hydrogen energy could be stored and used.

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Language：English   Publisher：The Japan Society of Sonochemistry  

Strong emission in liquid is observed by radio frequency irradiation using a submerged electrode. Plasma is generated in liquid, and because the liquid around the plasma is evaporated instantly, the plasma seems as if to be generated in a bubble. We measured the spectrum of the plasma emission, analyzed the produced gas by plasma in water and also measured the production rate of hydrogen gas. The mole ratio of hydrogen to the produced gas is 90 to 99% and the rate of hydrogen gas is 1.2 to 2.3 larnol/s at 150 W. The rate of the hydrogen gas decreases with increase of the pressure from 60 to 100 kPa. To clarify the gas production mechanism, we carried out numerical simulations of the chemical reactions inside and outside the bubble. As a result, the mole ratio of the produced gas is .approximately agreeable to the experimental result.

DOI： 10.20577/pamjss.20.0_97

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Plasma was generated in water by irradiation at high frequency of 13.56 MHz, and the behavior of bubbles including the plasma was observed by a high-speed camera. The generation pattern of the bubbles was classified into four types according to liquid temperature and supplied power. Conducting the simulation, the maximum temperature in the bubble was found to be from 3500 K to 4300 K. and the decomposition of water molecule occurred. The gas in the bubble was found to become high ratio of hydrogen. The phenomenon can be regarded as a film boiling of exceptionally high heat flux. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijheatmasstransfer.2010.03.021

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

The characteristics of diamond synthesis by 2.45 GHz microwave plasma chemical vapor deposition (CVD) under pressures greater than atmospheric pressure were investigated. The deposits on Si substrates were identified by scanning electron microscopy and Raman spectroscopy. The growth rate of diamond was found to be 250 mu m/h at 300 kPa, which is ten times greater than that of the conventional low-pressure CVD method. In order to make high-speed deposition of diamond effective, the diamond growth rates for gas-phase microwave plasma CVD were compared to those from the in-liquid plasma CVD method. The growth rate was found to increase as system pressure increased, displaying the same tendency of that in-liquid plasma CVD. The amounts of input microwave energy per unit volume of diamond in the gas-phase and in-liquid plasma CVD methods were also compared. The amount of input microwave energy per unit volume of diamond was found to be 0.6 to 1 kWh/mm(3). (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.diamond.2009.12.018

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

The effect of the shape of the electrode to generate 2.45 GHz microwave plasma in pure water is examined. Three variations of a common coaxial electrode are proposed, and compared according to the power required for plasma ignition and the position of plasma ignition in pure water at 6 kPa using a high-speed camera. These coaxial electrodes are calculated using three-dimensional finite-difference time-domain method calculations. The superior shape of coaxial electrode is found to be one with a flat plane on the tip of the inner electrode and dielectric substance located below the tip of the outer electrode. The position of the plasma ignition is related to the shape of the coaxial electrode. By solving the heat-conduction equation of water around the coaxial electrode taking into account the absorption of the microwave energy, the position of the plasma ignition is found to be not where electric field is the largest, but rather where temperature is maximized.

DOI： 10.1063/1.3319616

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The degradation of methylene blue by radio frequency (RF) plasmas in water under ultraviolet (UV) irradiation was studied experimentally. When the methylene blue solution was exposed to RF plasma, UV irradiation from a mercury vapor lamp enhanced degradation significantly. A lamp without power supply also enhanced degradation since weak UV light was emitted weakly from the lamp due to the excitation of mercury vapor by stray RF power. Such an enhancement is explained by the fact that after hydrogen peroxide is produced via the recombination process of OH radicals around the plasma, OH radicals reproduced from hydrogen peroxide via the photolysis process degrade methylene blue. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jhazmat.2009.09.076

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PubMed

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

Distributions of emission intensity from radicals, electron temperature, and rotational temperature at a radio frequency of 27.12 MHz plasma in water are clarified by detailed spectroscopy measurement. Through this investigation, the following were observed. The points of maximum emission intensity of H alpha, H beta, O (777 nm), and O (845 nm) are almost the same, while that of OH shifts upward. The electron temperature decreases, while the rotational temperature increases with pressure. The distribution of the electron temperature changes at a threshold pressure, which is concerned with a change in the electron discharge mechanism. The self-bias of the electrode changes from a negative to positive at a threshold pressure. The point of the maximum rotational temperature of OH radicals shifts to approximately 1 mm above that for the maximum intensity of OH emission.

DOI： 10.1063/1.3264671

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

Hydrogen is produced by generating in-liquid plasma in a conventional microwave oven. A receiving antenna unit consisting of seven copper rods is placed at the bottom of the reactor furnace in the microwave oven. 2.45 GHz microwave in-liquid plasma can be generated at the tips of the electrodes in the microwave oven. When the n-dodecane is decomposed by plasma, 74% pure hydrogen gas can be achieved with this device. The hydrogen generation efficiency for a 750 W magnetron output is estimated to be approximately 56% of that of the electrolysis of water. Also, in this process up to 4 mg/s of solid carbon can be produced at the same time. The present process enables simultaneous production of hydrogen gas and the carbide in the hydrocarbon liquid. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3236575]

DOI： 10.1063/1.3236575

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

In order to make high-speed deposition of diamond effective, diamond growth rates for gas-phase microwave plasma chemical vapor deposition and in-liquid microwave plasma chemical vapor deposition are compared. A mixed gas of methane and hydrogen is used as the source gas for the gas-phase deposition, and a methanol solution of ethanol is used as the source liquid for the in-liquid deposition. The experimental system pressure is in the range of 60-150 kPa. While the growth rate of diamond increases as the pressure increases, the amount of input microwave energy per unit volume of diamond is 1 kW h/mm(3) regardless of the method used. Since the in-liquid deposition method provides a superior cooling effect through the evaporation of the liquid itself, a higher electric input power can be applied to the electrodes under higher pressure environments. The growth rate of in-liquid microwave plasma chemical vapor deposition process is found to be greater than conventional gas-phase microwave plasma chemical vapor deposition process under the same pressure conditions. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3117198]

DOI： 10.1063/1.3117198

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

Spectroscopic measurements of high frequency (hf) plasma were performed under high pressure conditions (5 and 7 MPa) and supercritical (sc) CO2 conditions (8-20 MPa). Temperature evaluated from C-2 Swan bands (d (3)Pi(g)-&gt; a (3)Pi(u)) increased from 3600 to 4600 K with an increase in pressure. The first observation of broadening and shifting of the O I line profile (3p (5) P-3,P-2,P-1 -&gt; 3s (5) S-2(0)) of hf plasma under sc CO2 conditions was carried out. However, the origin of broadening and the shifting cannot be understood because the present theory explaining them is not valid for such high pressure conditions.

DOI： 10.1063/1.3091927

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOCIETY APPLIED PHYSICS  

The synthesis of diamond using in-liquid plasma chemical vapor deposition (CVD) is investigated in this study. Plasma in methanol solution is generated by applying microwave radiation of 2.45 GHz. The composition of the solution and the pressure in the container were varied as experimental parameters. No substrate cooling equipment was required in this process owing to the cooling effect of the liquid itself. The deposits on Si substrates were identified by scanning electron microscopy (SEM) and Raman spectroscopy. A diamond film containing impurities, which was confirmed to have a growth rate of 192 mu m/h, was obtained. The deposit had sufficient hardness within the 15 to 80 GPa range, which is suitable for industrial hard coating. Deposition rate increased as system pressure increased, displaying the same tendency of conventional microwave CVD. Optical emission spectroscopy was used to characterize the in-liquid plasma for chemical reaction. (C) 2009 The Japan Society of Applied Physics

DOI： 10.1143/JJAP.48.031601

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：UNIVERSITEIT GENT  

We generated radio frequency (RF) plasma in water at atmospheric pressure by applying RF power of 13.56 MHz from an electrode. Emission lines from the plasma suggest that OH radicals, hydrogen, and oxygen were generated. On comparing the experimental and calculated spectral lines of the OH radical (A-X), we observed that the temperature of the radical is around 3,600 K. From the Stark broadening of the Ho line, we evaluated the electron density of the plasma; it was about 3 X 10(20) m(-3). Methylene blue solution was exposed to the plasma, and it underwent degradation. Oxidation by the OH radical may have caused this degradation. Hydrogen peroxide was also produced during the process of generation of plasma in water.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

A new high-rate crystal diamond synthesis method using plasma submerged in liquid alcohol was developed. The diamonds are grown by contact with the in-liquid plasma created by applying microwaves to a liquid methanol solution. The chemical reaction rate in the plasma is much higher than in the conventional gas phase plasma because the plasma is stably generated in a bubble in the liquid solution. Therefore, a very high diamond deposition rate (100 mu m/h) becomes possible even under low pressure. The success of this method will be the foundation for the high-volume supply of low-cost diamond substrate. (C) 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.diamond.2008.04.010

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Language：Japanese   Publisher：日本実験力学会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Radio frequency (RF) plasma in water was used for the degradation of methylene blue. The fraction of decomposition of methylene blue and the intensity of the spectral line from OH radical increased with RF power. RF plasma in water also produced hydrogen peroxide. The density of hydrogen peroxide increased with RF power and exposure time. When pure water (300 mL) is exposed to plasma at 310 W for 15 min, density of hydrogen peroxide reaches to 120 mg/L. Methylene blue after exposed to plasma degraded gradually for three weeks. This degradation may be due to chemical processes via hydrogen peroxide and tungsten. The comparison between the experimental and calculated spectral lines of OH radical (A-X) shows that the temperature of the radical is around 3,500 K. Electron density is evaluated to be similar or equal to 3.5 x 10(20) m(-3) from the stark broadening of the H(beta) line.

DOI： 10.1007/s11090-008-9142-2

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

The plasma in water is generated by applying high-frequency (HF) irradiation of 27.12 MHz or microwave (MW) radiation of 2.45 GHz from an electrode. The electrode is heated by joule heating by the HF or MW irradiation, and vapor bubbles are generated simultaneously. The plasma is then ignited inside the bubbles on the electrode. The glow discharge plasma can be maintained in spite of atmospheric pressure due to the cooling effect of the liquid itself. The electron temperature of the plasma generated by the 27.12 MHz radiation is higher than that generated by the 2.45 GHz radiation. (C) 2008 The Japan Society of Applied Physics.

DOI： 10.1143/APEX.1.046002

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Language：Japanese   Publisher：The Heat Transfer Society of Japan  

DOI： 10.11368/nhts.2008.0.99.0

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.11368/tse.16.131

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Language：Japanese   Publisher：社団法人プラズマ・核融合学会  

近年のプラズマ生成技術の飛躍的な向上によって,大気圧以上の高密度媒体で形成される反応性プラズマ,いわゆる&quot;大気圧プラズマ&quot;が大きな注目を集めるようになり,基礎から応用にいたる様々な研究が学際横断的に行われている.本講座では,代表的な大気圧プラズマとして,コロナ放電,誘電体バリア放電,パルスアーク放電,大気圧グロー放電,液中プラズマを取り上げ,学部・大学院生などの初学者を対象に,種々の大気圧プラズマを安全かつ簡単に発生させるための基本原理,実験装置,注意点などを紹介する.また,大気圧プラズマを発生させる上で重要となる,高電圧発生方法,高周波回路の設計,取り扱いについても概説し,実験の指針とする.最後に,感電,有毒ガスの発生など実験に際しての注意事項,安全対策について述べる.

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Other Link： http://dl.ndl.go.jp/info:ndljp/pid/10456921

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

A supercritical carbon dioxide (CO2) plasma process for fabricating one-dimensional tungsten oxide nanowires coated with amorphous carbon is presented. High-frequency plasma was generated in supercritical carbon dioxide at 20 MPa by using tungsten electrodes mounted in a supercritical cell, and subsequently an organic solvent was introduced with supercritical carbon dioxide into the plasma. Electron microscopy and Raman spectroscopy investigations of the deposited materials showed the production of tungsten oxide nanowires with or without an outer layer. The nanowires with an outer layer exhibited a coaxial structure with an outer concentric layer of amorphous carbon and an inner layer of tungsten oxide with a thickness and diameter of 20-30 and 10-20 nm, respectively.

DOI： 10.1088/0957-4484/18/49/495603

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

A supercritical carbon dioxide (CO2) plasma process for fabricating one-dimensional tungsten oxide nanowires coated with amorphous carbon is presented. High-frequency plasma was generated in supercritical carbon dioxide at 20 MPa by using tungsten electrodes mounted in a supercritical cell, and subsequently an organic solvent was introduced with supercritical carbon dioxide into the plasma. Electron microscopy and Raman spectroscopy investigations of the deposited materials showed the production of tungsten oxide nanowires with or without an outer layer. The nanowires with an outer layer exhibited a coaxial structure with an outer concentric layer of amorphous carbon and an inner layer of tungsten oxide with a thickness and diameter of 20-30 and 10-20 nm, respectively.

DOI： 10.1088/0957-4484/18/49/495603

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Language：Japanese   Publisher：化学工業社  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

The behavior of 2.45 GHz microwave in-liquid plasma n-dodecane was observed using a high-speed camera. The system pressure before plasma generation was 1 or 100 hPa. The plasma was generated at the tip of a sharpened electrode, after which the plasma was found in a bubble in the liquid on the electrode. The plasma did not continuously emit light. The profile of light intensity varied between 1 and 100hPa when the plasma faded. The behavior of the bubble by heat generation in the bubble was numerically simulated. To match experimental results, the heat generation was continued for 0.9 ms at 1hPa and throughout the simulation at 100hPa. The internal temperature ranged from 2,000 to 4,000K, and the ratio of vapor n-dodecane to hydrogen produced by chemical reaction was at almost the same order at 1 hPa and approximately 1% at 100 hPa.

DOI： 10.1143/JJAP.46.6015

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

An experiment was conducted for generating high-frequency plasma in supercritical carbon dioxide; it is expected to have the potential for applications in various types of practical processes. It was successfully generated at 6-20 MPa using electrodes mounted in a supercritical cell with a gap of 1 mm. Emission spectra were then measured to investigate the physical properties of supercritical carbon dioxide plasma. The results indicated that while the emission spectra for carbon dioxide and carbon monoxide could be mainly obtained at a low pressure, the emission spectra for atomic oxygen could be obtained in the supercritical state, which increased with the pressure. The temperature of the plasma in supercritical state was estimated to be approximately 6000-7000 K on the assumption of local thermodynamic equilibrium and the calculation results of thermal equilibrium composition in this state showed the increase of atomic oxygen by the decomposition of CO2. (C) 2007 American Institute of Physics.

DOI： 10.1063/1.2724240

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Language：Japanese   Publisher：一般社団法人日本機械学会  

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Language：Japanese   Publisher：一般社団法人日本機械学会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACOUSTICAL SOC AMER AMER INST PHYSICS  

A noncontact transport experiment in water using ultrasonic traveling waves was investigated. Acrylic, aluminum, and brass discs were used as test objects. Traveling waves were generated using two ultrasonic transducers attached at the ends of a vibrating plate. One side was used as the wave-source side and the other side was used as the wave-receiving side. Acrylic plates cemented to the sides of the vibrating plate formed a tank to hold water. Object transportation was accomplished by adding a small amount of water to the vibrating structure. The transport velocity of floating objects in water is faster than for floating transport in air because of. buoyancy. The transport velocity of an object depends on water height. The minimum value of the velocity occurs when the disc thickness is equal to the water height. The transport velocity increases as the height of water increases. For very shallow depths, the largest velocity is obtained when cavitation-induced streaming occurs. (c) 2007 Acoustical Society of America.

DOI： 10.1121/1.2436708

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACOUSTICAL SOC AMER AMER INST PHYSICS  

A noncontact transport experiment in water using ultrasonic traveling waves was investigated. Acrylic, aluminum, and brass discs were used as test objects. Traveling waves were generated using two ultrasonic transducers attached at the ends of a vibrating plate. One side was used as the wave-source side and the other side was used as the wave-receiving side. Acrylic plates cemented to the sides of the vibrating plate formed a tank to hold water. Object transportation was accomplished by adding a small amount of water to the vibrating structure. The transport velocity of floating objects in water is faster than for floating transport in air because of. buoyancy. The transport velocity of an object depends on water height. The minimum value of the velocity occurs when the disc thickness is equal to the water height. The transport velocity increases as the height of water increases. For very shallow depths, the largest velocity is obtained when cavitation-induced streaming occurs. (c) 2007 Acoustical Society of America.

DOI： 10.1121/1.2436708

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS INC  

The purpose of this study is to elevate the temperature and induce necrosis tumor cells that include ferrite powder to 50-60 degrees C by applying an alternating magnetic field. The achieved temperature is higher when compared to the conventional hyperthermia methods. We performed an experiment in which a high-water content agar phantom that was used as a quasi-tissue had 50 nm-10 mu m magnesium ferrite (MgFe2O4) dispersed in it and was then heated to a level of 190-700 kHz. The results show that the temperature of the phantom is higher for higher frequencies, larger particle sizes, and higher quantities of dispersed ferrite powder. Also, taking into account heat generation due to the magnetic powder, heat generation due to tissue metabolism, and the cooling effect of the blood flow, we solved the thermal equation related to local thermal therapy. Small differences in the distribution of ferrite powder affect the temperature increase of the tissue and the area where cell necrosis is induced.

DOI： 10.1080/01457630701483711

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASME-AMER SOC MECHANICAL ENG  

To minimize surgical stresses including blood loss and operation time to the patients during hepatic resection, we studied the feasibility of a combination of a partial liver freezing technique and shape-memory alloy, which also enables a free-designed resection curve. In this surgical procedure, the region surrounding a tumor in the liver is frozen to excise and prevent hemorrhage. The liver was frozen by a Peltier module. The effects of cooling rate and freezing temperature on the excision force that arise between a scalpel and the liver are carried out experimentally as a basic research for partial freezing surgical procedures. A porcine liver was used as a liver sample. The physical properties were estimated by using the finite element method based on the heat transfer characteristics of the liver. Isolation of the liver was conducted using a scalpel attached to the end-effector of a 3 degrees of freedom robot. In the experiments, the minimum excision force was obtained at a temperature between 272 K and 275 K; therefore, it is preferable that the liver be excised within this temperature range. Lowering of the cooling rate decreases the excision force even if the temperature of the liver remains unchanged. The lower the temperature of the liver is, the larger the increment rate of excision force is with regard to the cooling rate.

DOI： 10.1115/1.2244577

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Publisher：Acoustical Society of America (ASA)  

<jats:p>In-liquid plasma is a useful invention because its chemical reaction rate is several thousand times higher than those of conventional plasma techniques. However, in-liquid plasma is not so familiar now because its fundamental characteristics remain unclear. We investigated characteristics of in-liquid plasma in a continuous liquid flow to facilitate its application as a chemical decomposition or synthesis device. N-dodecane is supplied by the pump and a stable liquid flow is set in the rectangular vessel. Because the flow velocity is insufficient, a nozzle is set 2 mm distant from the microwave electrode tip. The average flow velocity of n-dodecane at the nozzle top is 0–19 m/s and the Reynolds number is as high as 1.2×104. A 2.45-GHz microwave is introduced by a monopole antenna electrode inserted into a rectangular cavity resonator. In-liquid plasma is generated and observed in the flowing cavitation bubbles generated from the ultrasonic horn tip. The vessel’s inner pressure is adjusted to 65–450 hPa. The temperature in the plasma reached 3600±300 K; it was almost independent of the flow velocity because the physical properties of the plasma are influenced only slightly by the acoustic cavitation stream.</jats:p>

DOI： 10.1121/1.4788092

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Publisher：Acoustical Society of America (ASA)  

<jats:p>In-liquid plasma is generated by applying high-frequency (27 MHz) or microwave (2.45 GHz) radiation to hydrocarbon liquids or water. In-liquid plasma is expected to replace gas-phase plasma because the reaction rates for chemical deposition of in-liquid plasma are much higher than those for conventional vapor deposition. Moreover, the cooling effect of the liquid mitigates thermal damage to the substrate. In-plasma generation requires the existence of bubbles because this plasma occurs in bubbles in liquid. Two methods exist for generating bubbles. One is to generate vapor bubbles by heating the liquid. The other is to generate acoustic cavitaion bubbles. Sonoplasma is created when acoustic cavitation is used to generate in liquid plasma. This plasma is not arc-discharged plasma, but rather high-frequency or microwave plasma. Therefore, it is useful in many industrial applications. Using this technology as a chemical reactor, synthesis of diamondlike carbon, polycrystalline silicon carbide, and carbon nanotubes, decomposition of waste oils, and the production of hydrogen can be achieved easily in hydrocarbon liquids. Temperatures were measured from the ratio of emission intensities of Hα and Hβ. Plasma temperatures in hydrocarbon liquids are higher than those in water.</jats:p>

DOI： 10.1121/1.4788084

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Publisher：Acoustical Society of America (ASA)  

<jats:p>Behavior of a single bubble under an ultrasound resonant state in a hydrocarbon liquid such as n-dodecane or benzene was observed using a stroboscope and a charge-coupled device (CCD) camera. Although sonoluminescence was not confirmed because of bubble stability limitations, bubble deformation was observed at a situation of stability limitation. Deformation occurred when the bubble contracted to its minimum size. Numerical analyses of deformation growth by Rayleigh-Taylor instability of an oscillated bubble were carried out at the surface. The distortion amplitude of all degrees continued oscillating as the bubble expanded or contracted, and the oscillation frequency increased with the degree. The distortion amplitudes are amplified through the afterbounce by the resonance effect if the oscillation frequency of the distortion amplitude of some degree is approximately equal to the frequency of the afterbounce. The distortion amplitude of all degrees, except for amplified degrees, was dampened by the viscosity effect, and if the distortion amplitudes of all degrees were dampened, the bubble was considered to form a sphere and become stable. A phase diagram of stability of an oscillated bubble showed a function of an ambient bubble radius and the amplitude of forcing pressure.</jats:p>

DOI： 10.1121/1.4788090

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

We generate a radio frequency (RF) plasma in water at an atmospheric pressure by applying an RF power of 13.56 MHz from an electrode. The plasma is in a bubble formed in water. On the basis of hydrogen spectral lines under the assumption of thermal equilibrium, the temperature of the plasma is estimated to be 4000-4500K. Spectroscopic measurements show that hydrogen and oxygen are excited in the plasma. The plasma is also obtained in tap water or NaCl solution with a high conductivity. In the solution, sodium spectral lines are observed. Colored water containing methylene blue is exposed to the plasma. The absorbence spectra of the colored water before and after exposure to the plasma suggest the decomposition of organic matter due to chemical reactions involving active species, such as OH-radicals.

DOI： 10.1143/JJAP.45.8864

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

Needle-type materials were studied for the, application of thermal coagulation therapy in an AC magnetic field. We found that the Ti tube filled with ferrite powder as the core had a high heat generation ability in an AC magnetic field. Although the Ti tube without the ferrite powder or Ti rod showed poor heat generation abilities, the temperature was significantly increased by the existence of ferrite powder in the tube. In this case, the ferrite powder seems to improve the eddy loss for the Ti tube. The maximum heat generation ability was obtained for the Ti tube that contained MgFe2O4 powder in the examined Ti tube with some ferrites.

DOI： 10.1143/JJAP.45.8673

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

We propose to apply plasma in liquid to replace gas-phase plasma because we expect much higher reaction rates for the chemical deposition of plasma in liquid than for chemical vapor deposition: A reactor for producing microwave plasma in a liquid could produce plasma in hydrocarbon liquids and waste oils. Generated gases consist of up to 81% hydrogen by volume. We confirmed that fuel gases such as methane and ethylene can be produced by microwave plasma in liquid. (c) 2006 American Institute of Physics.

DOI： 10.1063/1.2210448

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

We propose to apply plasma in liquid to replace gas-phase plasma because we expect much higher reaction rates for the chemical deposition of plasma in liquid than for chemical vapor deposition: A reactor for producing microwave plasma in a liquid could produce plasma in hydrocarbon liquids and waste oils. Generated gases consist of up to 81% hydrogen by volume. We confirmed that fuel gases such as methane and ethylene can be produced by microwave plasma in liquid. (c) 2006 American Institute of Physics.

DOI： 10.1063/1.2210448

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

The generation of microwave plasma in liquid with vapor bubbles has been achieved and will soon be applied to high-speed chemical vapor deposition. Vapor bubbles are induced from an electrode by heating. The deposition rate of diamondlike carbon films depends on the pressure and the power of the microwave supply. Polycrystalline silicon carbide is synthesized on a silicon substrate in a mixture of n-dodecane and silicone oil. The dispersion of water droplets in liquid creates many pores on the silicon carbide films. The synthesis of carbon nanotubes can be achieved in liquid benzene. (c) 2006 American Institute of Physics.

DOI： 10.1063/1.2208167

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

The behavior of cavitation bubbles is important in sonoplasma, which is generated by simultaneous microwave and ultrasound irradiation. Sonoplasma is expected to be applied in great many fields, such as high-speed chemical vapor deposition. In this study, the behavior of a single bubble in n-dodecane with ultrasonic irradiation was first observed using a charge-coupled-device camera and a stroboscope. In the observation, though sonoluminescence was not confirmed, the bubble was expanded and contracted synchronously with the ultrasonic frequency and was deformed when it contracted to its minimum size. The mechanism of the deformation of the bubble was clarified by numerical analysis. The stability of the bubble can be determined according to initial radius and the amplitude of the sound pressure.

DOI： 10.1143/JJAP.45.4165

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The purpose of this study is to investigate the thermal characteristics of Mg1-XCaXFe2O4 ferrite powder by applying AC magnetic field and to predict the effect of thermal coagulation in vivo. We found that heating characteristics of the ferrite powder became greater as the frequency through the 400 kHz to 700 kHz range. The highest heat generation was attained using 7-15 nm ferrite powder. We also carried out a heat transfer simulation in which we were able to demonstrate that this material has sufficient heat generating characteristics to thermally coagulate a tumor cell and that it is possible to predict the range of the coagulation from the present simulation. (c) 2006 Springer Science + Business Media, Inc.

DOI： 10.1007/s10853-006-6749-7

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Textile Machinery Society of Japan  

The present study is concerned with numerical simulation of air flow in a yarn duct of an interlacer, which is an apparatus for yarn intermingling. A nozzle of circular pipe of inner diameter d(&lt
D) is mounted perpendicularly to the yarn duct of circular pipe of inner diameter D and length L. The air is injected from the nozzle into the yarn duct. This complex incompressible air flow of the interlacer system is analyzed by a numerical calculation program, FIDAP, using the high Reynolds number k-ε model. The air flow in the yarn duct can be simulated well by this analysis for d/D≤0.5. For d/D≥0.75, however, the predicted results for air flow in the yarn duct are not in satisfactory agreement with the measurements. The effect of the value of d/D on the air flow in the yarn duct is discussed. It is clearly found that for d/D≤0.5 the circumferential air flow along the inner wall of the yarn duct is dominant, while for d/D&gt
0.75 the axial air flow is dominant. The interlacer with 0.5≤d/D≤0.7 is usually used in the practical interlacing processing, where the condition of the air flow largely changes from circumferential to axial flow. Furthermore, the ratio L/D has no great effect on the flow in the yarn duct for L/D≥7. © 2006 The Textile Machinery Society of Japan.

DOI： 10.4188/jte.52.73

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：一般社団法人 日本繊維機械学会  

The present study is concerned with numerical simulation of compressible air flow in a yarn duct of an interlacer and the relation between air flow and yarn entanglement. A nozzle of circular pipe of inner diameter d (&lt
D) is mounted perpendicularly to the yarn duct of circular pipe of inner diameter D (d&lt
D). The interlacer system is analyzed numerically using the high Reynolds number k-ε model. The dependence of compressible air flow on the ratio d/D is examined numerically and experimentally. When the average local Mach number at the entrance of the nozzle pipe reaches 0.5-0.71, the flow chokes immediately after passing the nozzle pipe. The limited Mach number at the entrance of the nozzle pipe depends on the flow in the nozzle pipe, namely the friction loss. Furthermore the strength and the number of yarn entanglement vary with d/D and become maximums at d/D % 0.5. © 2006 The Textile Machinery Society of Japan.

DOI： 10.4188/jte.52.121

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Language：Japanese   Publishing type：Research paper (scientific journal)  

The present study is concerned with numerical simulation of compressible air flow in a yarn duct of an interlacer and the relation between air flow and yarn entanglement. A nozzle of circular pipe of inner diameter d (&lt
D) is mounted perpendicularly to the yarn duct of circular pipe of inner diameter D (d&lt
D). The interlacer system is analyzed numerically using the high Reynolds number k-ε model. The dependence of compressible air flow on the ratio d/D is examined numerically and experimentally. When the average local Mach number at the entrance of the nozzle pipe reaches 0.5-0.71, the flow chokes immediately after passing the nozzle pipe. The limited Mach number at the entrance of the nozzle pipe depends on the flow in the nozzle pipe, namely the friction loss. Furthermore the strength and the number of yarn entanglement vary with d/D and become maximums at d/D % 0.5. © 2006 The Textile Machinery Society of Japan.

DOI： 10.4188/jte.52.121

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Textile Machinery Society of Japan  

The present study is concerned with numerical simulation of air flow in a yarn duct of an interlacer, which is an apparatus for yarn intermingling. A nozzle of circular pipe of inner diameter d(&lt
D) is mounted perpendicularly to the yarn duct of circular pipe of inner diameter D and length L. The air is injected from the nozzle into the yarn duct. This complex incompressible air flow of the interlacer system is analyzed by a numerical calculation program, FIDAP, using the high Reynolds number k-ε model. The air flow in the yarn duct can be simulated well by this analysis for d/D≤0.5. For d/D≥0.75, however, the predicted results for air flow in the yarn duct are not in satisfactory agreement with the measurements. The effect of the value of d/D on the air flow in the yarn duct is discussed. It is clearly found that for d/D≤0.5 the circumferential air flow along the inner wall of the yarn duct is dominant, while for d/D&gt
0.75 the axial air flow is dominant. The interlacer with 0.5≤d/D≤0.7 is usually used in the practical interlacing processing, where the condition of the air flow largely changes from circumferential to axial flow. Furthermore, the ratio L/D has no great effect on the flow in the yarn duct for L/D≥7. © 2006 The Textile Machinery Society of Japan.

DOI： 10.4188/jte.52.73

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

Heat transfer enhancement using a horn-type transducer was carried out in the natural convection region while a flat plate was used as a wall-like obstacle in front of the heating surface. Three types of plate were used as obstacles: acrylic, aluminum, and Styrofoam. A horn tip of 6 mm diameter and 60.7 kHz was used as the ultrasonic transducer. The acoustic cavitation jet induced by the ultrasonic vibration exhibited the same tendency as the axisymmetric freejet. The acoustic jet from the horn tip was shut out by the flat plate; however, the ultrasound passed through the flat plate and transferred the flow effect and agitation effect to the area behind the plate. By applying ultrasonic vibration, the heat transfer coefficient of the heating surface behind the flat plate was increased by up to threefold. The heat transfer coefficient decreased as the thickness of the flat plate increased. The heat transfer coefficient was the highest for the acrylic plate, then the aluminum plate, and lowest for the Styrofoam plate.

DOI： 10.1143/JJAP.44.4674

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

The mechanism of cavitation bubble streaming by ultrasonic vibration in a water tank was experimentally investigated. A standard ultrasonic cleaner unit with a resonant frequency of 40 kHz was used as an ultrasonic generator. The behavior of the streaming was visualized by the schlicren method and sonochemical luminescence, and the velocity of the streaming was measured by laser Doppler velocity measurement equipment (LDV). The cavitation bubble streaming has two structures. A cavitation cloud, which consists of many cavitation bubbles, is shaped like a facing pair of bowls with a diameter of approximately 1/3 the wavelength of the standing wave, and moves inside the standing-wave field with a velocity of 30 to 60 mm/s. The cavitation bubbles move intensely in the cloud with a velocity of 5 m/s at an ultrasonic output power of 75 W. The streaming is completely different from conventional acoustic streaming. Also the cavitation bubble is generated neither at the pressure node nor at the antinode.

DOI： 10.1143/JJAP.44.3161

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Selection of ferrite powder was carried out to realize a thermal coagulation technique in which tumors are locally heated by an application of alternating magnetic field from external coils. Magnesium ferrite (MgFe2O4) showed the largest increase in temperature (AT) under an alternating magnetic field in all the ferrites examined. For all the samples, AT value under alternating magnetic field was increased with an increase in frequency (200-500 kHz). The heating ability for the Mg-ferrite was ca. 1.4 W/g under alternating magnetic field of 4.0 kA/m (200 W, 370 kHz). The heating ability in alternating magnetic field was clearly depended on the magnitude of the hysteresis loss for the ferrite powder. (C) 2005 Springer Science + Business Media, Inc.

DOI： 10.1007/s10853-005-5698-x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

Stable plasma can be generated in a liquid hydrocarbon such as n-dodecane or benzene by simultaneous microwave and ultrasonic irradiation. The authors refer to this plasma as "sonoplasma" and distinguish it from "sonoluminescence" on the basis of the continuity of emission. The temperature in the plasma was obtained by measuring two specified emission intensities from the plasma which reached approximately 5000 K. To analytically estimate the temperature, numerical simulations of the behavior of a single bubble in sound field, taking into account the absorption of microwave energy, were carried out. The temperature inside the bubble in n-dodecane reached approximately 8000 K. In benzene, the temperature inside the bubble, which continued expanding through absorption of microwave energy, exceeded 2000 K.

DOI： 10.1143/JJAP.43.2833

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

Plasma chemical vapor deposition (plasma CVD) is a generic term for methods in which a precursor containing a material to be deposited is dissociated in a plasma where it is subject to chemical reactions, and is then deposited as a film on the surface of a heated substrate. A drawback of plasma CVD is that this process cannot be used to synthesize large amounts of adsorbate, or to deposit onto substrates that are vulnerable to high temperatures. As liquids are much denser than gases, synthesis rates are thought to be much higher in the former. The authors have observed the ignition and maintenance of a stable plasma in a liquid hydrocarbon exposed to a combination of ultrasonic waves and microwave radiation. Microwave energy is effectively injected into the interior of acoustic cavitation bubbles, which act as nuclei for the ignition and maintenance of the plasma. Because the plasma is formed in a liquid environment, it is possible to obtain much higher film deposition rates at much lower plasma temperatures than ever before. In addition, this process can be carried out at normal temperatures and pressures. (C) 2003 American Institute of Physics.

DOI： 10.1063/1.1631062

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Language：Japanese   Publisher：日本工業出版  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

The behavior of a single bubble rising in an ultrasonic standing wave field through vertical pipes filled with a quiescent liquid is analyzed numerically using the cubic-interpolated pseudo-particle(CIP)-combined and unified procedure(C-CUP) method. The calculated terminal velocities of bubbles in pipes agree with the experimental results in silicon oil. As the diameter of the bubble approaches the pipe diameter, the shape of the bubble is deformed into a lengthwise ellipse and rising velocity slows due to the pipe wall. The velocities and shapes of single bubbles are obtained for both standing waves formed in the axial direction of pipes and in the radial direction. When ani initial spherical bubble rises through the node of the radially formed standing wave in pipes, it is deformed into a lengthwise elliptical shape by the acoustic radiation force even if the wall effect is small, and the velocity of the bubble is faster than that for when there is no ultrasonic field. In other cases, the average terminal velocity of bubbles is slower than that for when there is no ultrasonic field.

DOI： 10.1143/JJAP.42.2975

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Language：Japanese   Publisher：Japanese Society for Engineering Education  

The basic scientific and technological knowledge and experience that incoming students of our university possess have been inspected. It was clearly shown that such knowledge was based not on experience but on desk work. Usually students had not had the opportunity to obtain such knowledge in actual situations, and many students lost interest in studying engineering. In order to improve this situation and produce creativity in students, we developed a laboratory course to provide fundamental scientific and technical experience to our freshmen. This academic year(2002), over 340 students belong to four different departments will take this new course. The preliminary outcomes will be reported.

DOI： 10.4307/jsee.51.2_31

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The behavior of solid spherical particles and air bubbles moving in an ultrasonic standing wave field are investigated experimentally. An ultrasonic transducer of 45 kHz is fixed at the part of the wall of the vertical square channel, and a standing wave field can be formed horizontally in this section. Several small pipes are inserted in this channel and particles and bubbles are dropped or raised into the pipes respectively. In the experiment for solid particles falling or rising in a liquid, the average terminal velocity in an ultrasonic field is slower than that in which there is no ultrasonic field. In the case of bubbles, the path of spherical bubbles in pipes strongly changes depending upon which position (node or antinode of sound pressure) in the standing wave field it passes. The rising velocity of non-spherical bubbles is faster than that of those with no ultrasonic application since the shape of bubble is deformed into a prolate ellipse by the ultrasonic force and the drag coefficient of bubble decrease.

DOI： 10.1299/kikaic.69.49

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DOI： 10.1299/kikaic.69.49

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

The purpose of this report is to investigate the heating effect of agar phantom containing ferrite powder by applying external AC magnetic field. Mg ferrite is most applicable for local hyperthermia. When using AC magnetic field with a frequency of 190 to 700kHz, the higher the frequency can increase the temperature of agarphantom containing 3.0 and 5.0% Mg ferrite powder. Even to the same weight of ferrite powder, the lager heat generation is obtained at the larger powder size. Moreover, a slight difference of distribution of ferrite powder has marked effects on the maximum temperature in vivo.

DOI： 10.1299/jsmemecjo.2003.7.0_57

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Language：Japanese   Publisher：日本工業出版  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

The effect of ultrasonic vibration in the Reynolds number (Re) range of 1500 to 6000 on fluid flow in a square channel was investigated experimentally. An ultrasonic transducer was fixed at the center of the bottom of a square test channel, and a standing wave field was formed in this channel. The velocity of the fluid was measured by a laser-Doppler velocimeter (LDV). By applying ultrasonic vibration to the laminar flow, agitation or disturbance of cavitation bubbles was produced in the flow and the transition to turbulent flow from laminar flow was promoted downstream. The ultrasonic vibration velocity near the wall is closely approximated by the expression of the log-law even if there exists a laminar flow region. In high Re regions, turbulence can be restrained by the ultrasonic vibration near the wall. Acoustic cavitation near the wall causes the reduction of turbulence intensity under turbulent regions. Since it is possible to control the fluid flow externally due to the easy transmission of ultrasonic vibration in liquids, this technique can be applied to fluid flow in various channels as a noncontact turbulence promoter.

DOI： 10.1143/JJAP.41.6601

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

The purpose of this study is to clarify experimentally the influence of streaming induced by ultrasonic vibration on heat transfer using a horn-type ultrasonic vibrator. A horn tip of 6 mm diameter and 60.7 kHz resonant frequency was used as the ultrasonic transducer. Heat transfer experiments for a downward-facing horizontal heating surface with ultrasonic vibration from below were carried out in a natural convection region. The acoustic jet in the water from the horn tip of the transducer regarded as a nozzle exit was induced by this transducer, and as a result, up to a ten-fold increase in heat transfer coefficient was obtained by application of 20 W in both tap water and degassed water. It was found that the mechanism of heat transfer enhancement by ultrasonic vibration in tap water can be classified into four categories. In degassed water, heat transfer enhancement is influenced not by the acoustic jet, but by small-scale perturbations by cavitation microjets.

DOI： 10.1143/JJAP.41.3217

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

The purpose of this study is to clarify the boiling in an inclined channel with rectangular section and the behavior of the bubble generated from the heated upper wall experimentally and analytically. This channel is submerged into the saturated pure water at inclination angle θ from horizontal and both sides of the channel are opened. The value of θ is between 2 and 20°, the height H of the channel is between 3 and 7 mm and the length of the heated part of the upper wall is 10 and 20 mm. As a result, the behavior of the coalescent bubble depends mainly on the height and the inclination angle of the channel and it is classified into 4 types. Heat transfer and burnout heat flux are related to the behavior of the coalescent bubble. Tip velocity of the coalescent bubble is calculated by one-dimensional model and burnout heat flux is predicted with using one-dimensional model.

DOI： 10.1299/kikaib.68.2834

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

The purpose of this study is to clarify the boiling in a horizontal channel and the one of the inclination angle θ of 5° with rectangular section and the behavior of bubble generated from the heated upper wall experimentally. This channel is submerged into the saturated pure water and both sides of the channel are opened. The height H of the channel is between 3 and 14.5 mm. In the case of θ of 0°, the whole heated wall is always covered with coalescent bubble and burnout occurs easily. In the case of θ of 5°, the condition of the heated wall surface depends on the channel height. For H ≤ 4 mm, nucleate boiling continues owing to the periodical inflow of water to the whole heated wall. For H ≥ 5 mm, the heat transfer is the nucleate boiling at a part of the heated wall and the natural convection at the other part. The slight inclination of the channel improves remarkably the characteristics of the heat transfer.

DOI： 10.1299/kikaib.68.2333

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

The purpose of this study is to clarify the boiling in a horizontal channel and the one of the inclination angle θ of 5° with rectangular section and the behavior of bubble generated from the heated upper wall experimentally. This channel is submerged into the saturated pure water and both sides of the channel are opened. The height H of the channel is between 3 and 14.5 mm. In the case of θ of 0°, the whole heated wall is always covered with coalescent bubble and burnout occurs easily. In the case of θ of 5°, the condition of the heated wall surface depends on the channel height. For H ≤ 4 mm, nucleate boiling continues owing to the periodical inflow of water to the whole heated wall. For H ≥ 5 mm, the heat transfer is the nucleate boiling at a part of the heated wall and the natural convection at the other part. The slight inclination of the channel improves remarkably the characteristics of the heat transfer.

DOI： 10.1299/kikaib.68.2333

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

The purpose of this study is to clarify the boiling in an inclined channel with rectangular section and the behavior of the bubble generated from the heated upper wall experimentally and analytically. This channel is submerged into the saturated pure water at inclination angle θ from horizontal and both sides of the channel are opened. The value of θ is between 2 and 20°, the height H of the channel is between 3 and 7 mm and the length of the heated part of the upper wall is 10 and 20 mm. As a result, the behavior of the coalescent bubble depends mainly on the height and the inclination angle of the channel and it is classified into 4 types. Heat transfer and burnout heat flux are related to the behavior of the coalescent bubble. Tip velocity of the coalescent bubble is calculated by one-dimensional model and burnout heat flux is predicted with using one-dimensional model.

DOI： 10.1299/kikaib.68.2834

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Language：English   Publisher：Acoustical Society of Japan  

This paper numerically analyzes the sound pressure on an object in an ultrasonic cleaning vessel by considering the dissipation of cavitation bubbles. To clarify the effect of ultrasonic attenuation on the number of cavitation bubbles, the cavitation intensity on a brass object is measured experimentally by changing the quantity of water. Then, the analyzed sound pressure results are compared with the measured cavitation intensity results. The energy dissipation by the oscillation of bubbles is estimated by the irreversible process of heat and mass transfer. The calculation is carried out for the natural oscillation and forced oscillation of cavitation bubbles. It is found that the dissipation of thermal conduction results from the radial oscillation of bubbles by ultrasound. The sound pressure calculated by this dissipation agrees with the cavitation intensity profile estimated using experimental results from the erosion loss of aluminum foil. As the quantity of the water in the cleaning vessel is increased, the sound pressure becomes lower. This is because the amount of energy dissipation of the ultrasonic wave increases proportionally to the number of bubbles. However, when the standing wave causes resonance between the ultrasonic generator and the block, the effect of the sound pressure on the bottom of the block is not disturbed by the water volume.

DOI： 10.1250/ast.22.283

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

The velocities of particle falling in a standing wave field through a vertical pipes filled with a stagnant liquid in are analyzed numerically for Reynolds number (Re) &lt; 1, for a wide range of pipe diameters. The equations of motion of a spherical particle in a viscous fluid are solved based on the Basset-Boussinesq-Ossen (BBO) equation to clarify the falling velocities in an infinite stagnant fluid. and two-dimensional hydrodynamic equations based on the cubic-interpolated pseudo-particle (CIP)-combined and unified procedure (C-CUP) method to clarify the effects of the walls of pipes. The velocity of a particle is periodically changed due to the influence of the radiation force of the standing wave. The average terminal velocity in a standing wave field is lower than that for which there is no ultrasonic field. As the particle diameter approaches the pipe diameter. the velocity of the particle approaches zero due to the influence of the pipe wall. The C-CUP method effectively simulates the behavior of a particle failing through a liquid-filled pipe in the standing wave field.

DOI： 10.1143/JJAP.40.3842

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：一般社団法人日本機械学会  

The purpose of this report is to clarify the behavior of single solid particles falling or rising in liquids with a standing wave field. The behavior of particles in degassed and ion exchanged water in the formation of a standing wave field was studied experimentally using an ultrasonic field of 45 kHz. In the experiment for particles falling in liquids, the decreased velocity of the glass particles in the ultrasonic field exhibited the greater deceleration in the degassed water, since the ultrasonic power effectively acts on a particle as a radiation force. In the case of the rising experiment, however, the greater deceleration of a particle is obtained in the ion exchanged water due to the motion of cavitaion bubbles. On the basis of this study, the falling velocity of a particle was analyzed numerically. The equation for motion of a sphere in a viscous fluid is based on the Basset-Boussinseq-Ossen equation, in addition to which, the acoustic radiation force must be included. The velocity of a particle is periodically changed due to influence of the radiation force of the standing wave. The terminal velocity of a small particle in an ultrasonic field is lower than that for which there is no ultrasonic field. © 2001, The Japan Society of Mechanical Engineers. All rights reserved.

DOI： 10.1299/kikaic.67.1255

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Language：English   Publishing type：Research paper (scientific journal)  

The purpose of this report is to clarify the behavior of single solid particles falling or rising in liquids with a standing wave field. The behavior of particles in degassed and ion exchanged water in the formation of a standing wave field was studied experimentally using an ultrasonic field of 45 kHz. In the experiment for particles falling in liquids, the decreased velocity of the glass particles in the ultrasonic field exhibited the greater deceleration in the degassed water, since the ultrasonic power effectively acts on a particle as a radiation force. In the case of the rising experiment, however, the greater deceleration of a particle is obtained in the ion exchanged water due to the motion of cavitaion bubbles. On the basis of this study, the falling velocity of a particle was analyzed numerically. The equation for motion of a sphere in a viscous fluid is based on the Basset-Boussinseq-Ossen equation, in addition to which, the acoustic radiation force must be included. The velocity of a particle is periodically changed due to influence of the radiation force of the standing wave. The terminal velocity of a small particle in an ultrasonic field is lower than that for which there is no ultrasonic field. © 2001, The Japan Society of Mechanical Engineers. All rights reserved.

DOI： 10.1299/kikaic.67.1255

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

The connection between the behavior of coalescent bubble generated from local heated upper wall and boiling characteristics in an inclined channel with rectangular cross section was studied experimentally and analytically. The channel was submerged at an inclination angle θ from horizontal (2・≦θ≦20・) in saturated water. The height of the channel H (3≦H≦7mm)and the heat flux were changed. The analytical model of bubble behavior was constructed and the method for prediction of the heat flux at the occurrence of burnout was proposed.

DOI： 10.1299/jsmemecjo.II.01.1.0_411

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Language：English   Publisher：Acoustical Society of Japan  

This paper numerically analyzes the sound pressure on an object in an ultrasonic cleaning vessel by considering the dissipation of cavitation bubbles. To clarify the effect of ultrasonic attenuation on the number of cavitation bubbles, the cavitation intensity on a brass object is measured experimentally by changing the quantity of water. Then, the analyzed sound pressure results are compared with the measured cavitation intensity results. The energy dissipation by the oscillation of bubbles is estimated by the irreversible process of heat and mass transfer. The calculation is carried out for the natural oscillation and forced oscillation of cavitation bubbles. It is found that the dissipation of thermal conduction results from the radial oscillation of bubbles by ultrasound. The sound pressure calculated by this dissipation agrees with the cavitation intensity profile estimated using experimental results from the erosion loss of aluminum foil. As the quantity of the water in the cleaning vessel is increased, the sound pressure becomes lower. This is because the amount of energy dissipation of the ultrasonic wave increases proportionally to the number of bubbles. However, when the standing wave causes resonance between the ultrasonic generator and the block, the effect of the sound pressure on the bottom of the block is not disturbed by the water volume.

DOI： 10.1250/ast.22.283

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Other Link： http://dl.ndl.go.jp/info:ndljp/pid/10572233

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Scripta Technica Inc  

The characteristics of boiling in a horizontal channel with changing conditions of the length of the heated wall and the channel height have been studied experimentally. Behavior of bubbles on the heated wall and growth of bubbles in the channel were observed by a high-speed camera. As a result, the behavior of the growth of bubbles which was classified into three types according to channel height had an influence on the time variation of the degree of superheat, heat transfer, and burnout heat flux in the channel. When the liquid on the bottom wall became thin, nucleate boiling with a vapor dome was observed on the heated wall. (C) 2000 Scripta Technica, Heat Trans Asian Res, 29(6): 459-472, 2000.

DOI： 10.1002/1523-1496(200009)29:6<459::AID-HTJ2>3.0.CO;2-T

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Scripta Technica Inc  

The characteristics of boiling in a horizontal channel with changing conditions of the length of the heated wall and the channel height have been studied experimentally. Behavior of bubbles on the heated wall and growth of bubbles in the channel were observed by a high-speed camera. As a result, the behavior of the growth of bubbles which was classified into three types according to channel height had an influence on the time variation of the degree of superheat, heat transfer, and burnout heat flux in the channel. When the liquid on the bottom wall became thin, nucleate boiling with a vapor dome was observed on the heated wall. (C) 2000 Scripta Technica, Heat Trans Asian Res, 29(6): 459-472, 2000.

DOI： 10.1002/1523-1496(200009)29:6<459::AID-HTJ2>3.0.CO;2-T

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：INTS PURE APPLIED PHYSICS  

In the present study, the flow pattern in a channel during application of ultrasonic vibration is investigated for the purpose of fluid control without contact. An ultrasonic transducer is fixed at the center of the bottom of a square test channel, and a standing wave field is formed in this channel. The velocity of the fluid is measured by a laser-Doppler velocimeter (LDV). By applying ultrasonic vibration to the channel flow, cavitation bubbles are generated at the sound pressure antinode in the channel when Re-d = 2000. Consequently, the cavitation bubbles act on the fluid as the barrier, causing the separation of the flow, and the velocity of the fluid is reduced locally. The generation of cavitation is active at the point where: the sound pressure of the standing wave formed by ultrasonic vibration is high. Moreover, the cavitation bubbles move toward to the antinode and are trapped by radiation pressure because the bubbles are of much lower density than water. Thus, the profile of fluid velocity is strongly influenced by the standing wave formed in the channel. Since the wavelength is shorter at higher frequencies, this technique can be applied to flows of various scales.

DOI： 10.1143/JJAP.39.4987

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Scripta Technica Inc  

The heat transfer coefficients during natural convection of water on a downward-facing horizontal surface and that on a vertical surface were measured under the influence of ultrasonic vibrations. The multi-type oscillation used in this experiment was able to operate at three frequencies-28, 45, and 100 kHz-not only continuously, but also intermittently. When ultrasonic vibrations of 28 and 45 kHz were applied to water, cavitation bubbles were generated and the heat transfer coefficient increased remarkably. When an ultrasonic vibration of 100 kHz was applied, the increase in the heat transfer coefficient was small compared to those at 28 and 45 kHz. At 100 kHz, cavitation was not observed at this low ultrasonic power. The uniformity of heat transfer, which depends on the profile of the standing wave due to the ultrasonic vibration, was improved by the method of repeatedly applying multiple vibrations. (C) 2000 Scripta Technica, Heat Trans Asian Res, 29(5): 358-372, 2000.

DOI： 10.1002/1523-1496(200007)29:5<358::AID-HTJ2>3.0.CO;2-3

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN J APPLIED PHYSICS  

The flow pattern induced by ultrasonic vibration in a water vessel is investigated experimentally using several liquids. In tap water, vortex streaming of cavitation bubbles around the pressure node of a standing wave occurred because of the large number of cavitation bubbles generated by the ultrasonic vibration. Acoustic streaming of the Rayleigh type caused by cavitation bubble streaming is also induced in tap water. In a glycerin aqueous solution of 30%, Eckart streaming, which flowed upward from the vibrator, occurred due to the dissipation of ultrasonic energy caused by viscosity, On the other hand, in degassed water, streaming is hardly generated at all since a uniform and stable standing wave is formed in the water vessel. The velocity of the acoustic streaming generated in the water vessel by 27.8 kHz vibration is 1 to 6 mm/s. The cavitation bubble streaming in tap water is completely independent of normal Rayleigh or Eckart streaming. This bubble streaming is considerably faster than previous streaming.

DOI： 10.1143/JJAP.39.3636

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

The present study is concerned with experiments and analyses of the movement of a liquid drop in a horizontal circular pipe exposed to air flow injected from a vertical circular pipe. Each inner diameter of the pipes is 30 mm and both ends of the horizontal pipe are open to the atmosphere. In the first experiment, a water drop is softly put on the inner wall of a horizontal acrylic resin pipe and its shape is examined. The approximate drop shape can be calculated from the law of minimum energy and the information obtained about the contact angle. In the second experiment, a water drop is exposed to airflow on a curved wall. It is clarified that this phenomenon is closely related to the gas flow in the horizontal pipe. And the relation between air flow and the stop position and the split -phenomena of liquid drop are examined experimentally and analytically.

DOI： 10.1299/kikaib.66.423

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Language：Japanese   Publisher：愛媛大学工学部  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

The flow pattern by ultrasonic vibration in a square channel was investigated as basic research into fluid control without contact. A turbulence promoter by ultrasonic vibration was proposed in this experiment. An ultrasonic transducer was fixed to the bottom of a square test channel, and a standing wave field was formed in this channel. The ultrasonic oscillators are bolted Langevin PZT -type vibrators with resonance frequencies of 25.4 kHz and 44.21 kHz and ultrasonic power varies in a range of 10 W to 80 W. The fluid velocity was measured by a Laser-Doppler velocimeter. By applying the ultrasonic vibrations into the laminar flow, the flow pattern in the channel was developed by the agitation or turbulence of cavitation bubbles, which consequently, changed from a laminar flow into a uniform flow. Since it is possible to control the fluid flow from outside due to the easy transmission of ultrasonic vibration in liquid, this technique can be applied to fluid flow in various channels as a non-contacting turbulence promoter.

DOI： 10.1299/kikaib.66.716

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

The flow pattern by ultrasonic vibration in a square channel was investigated as basic research into fluid control without contact. A turbulence promoter by ultrasonic vibration was proposed in this experiment. An ultrasonic transducer was fixed to the bottom of a square test channel, and a standing wave field was formed in this channel. The ultrasonic oscillators are bolted Langevin PZT -type vibrators with resonance frequencies of 25.4 kHz and 44.21 kHz and ultrasonic power varies in a range of 10 W to 80 W. The fluid velocity was measured by a Laser-Doppler velocimeter. By applying the ultrasonic vibrations into the laminar flow, the flow pattern in the channel was developed by the agitation or turbulence of cavitation bubbles, which consequently, changed from a laminar flow into a uniform flow. Since it is possible to control the fluid flow from outside due to the easy transmission of ultrasonic vibration in liquid, this technique can be applied to fluid flow in various channels as a non-contacting turbulence promoter.

DOI： 10.1299/kikaib.66.716

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

The present study is concerned with experiments and analyses of the movement of a liquid drop in a horizontal circular pipe exposed to air flow injected from a vertical circular pipe. Each inner diameter of the pipes is 30 mm and both ends of the horizontal pipe are open to the atmosphere. In the first experiment, a water drop is softly put on the inner wall of a horizontal acrylic resin pipe and its shape is examined. The approximate drop shape can be calculated from the law of minimum energy and the information obtained about the contact angle. In the second experiment, a water drop is exposed to airflow on a curved wall. It is clarified that this phenomenon is closely related to the gas flow in the horizontal pipe. And the relation between air flow and the stop position and the split -phenomena of liquid drop are examined experimentally and analytically.

DOI： 10.1299/kikaib.66.423

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Language：Japanese   Publisher：愛媛大学工学部  

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Language：Japanese   Publisher：愛媛大学工学部  

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Language：Japanese   Publisher：愛媛大学工学部  

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

A thin liquid film is left on wall after passage of a gas liquid interface front in a horizontal circular pipe filled up with water. The effect of the surface roughness of the inner surface of the pipe on the residual liquid film thickness is studied analytically and experimentally. Taking account of the increase of the pressure drop owing to the surface roughness of a wavy wall, the residual liquid film thickness on a wavy wall is analyzed by the same method as the thickness of film remaining on a surface of a solid withdrawn from a quiescent liquid. The numerical analysis of the pressure drop in a wavy wall channel is performed by an integral momentum method. The present study suggests that the surface roughness (2e) of the pipe effects on the residual liquid film thickness δ if δ&lt;2&lt;SUB&gt;ε&lt;/SUB&gt;.

DOI： 10.1299/kikaib.65.551

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

A thin liquid film is left on wall after passage of a gas liquid interface front in a horizontal circular pipe filled up with water. The effect of the surface roughness of the inner surface of the pipe on the residual liquid film thickness is studied analytically and experimentally. Taking account of the increase of the pressure drop owing to the surface roughness of a wavy wall, the residual liquid film thickness on a wavy wall is analyzed by the same method as the thickness of film remaining on a surface of a solid withdrawn from a quiescent liquid. The numerical analysis of the pressure drop in a wavy wall channel is performed by an integral momentum method. The present study suggests that the surface roughness (2e) of the pipe effects on the residual liquid film thickness δ if δ<2_ε.

DOI： 10.1299/kikaib.65.551

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Language：Japanese   Publisher：愛媛大学工学部  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

When gas is suddenly injected from a nozzle into a stationary liquid in a horizontal circular pipe, a thin liquid film is left on the wall after the passage of the interface front. The residual liquid film thickness in the case of the progress of the interface front at acceleratedly velocity is studied experimentally. The limit front velocity, to which the modified Bretherton's equation is applicable, depends on the Reynolds number, which the virtual diameter is used as the characteristic length. The residual liquid has a great influence on the tip velocity, and the variation of the tip velocity with the tip position is complex. At the position of the minimum acceleration of the liquid flow, the condition of the residual liquid changes.

DOI： 10.1299/kikaib.65.3305

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The heat transfer coefficients during natural convection of water on a downward-facing horizontal surface and that on a vertical surface were measured under the influence of ultrasonic vibration. The multi-type oscillator used in this experiment was able to irradiate in three different frequencies, 28, 45 and 100 kHz, not only continuously, but also intermittently. When ultrasonic vibrations of 28 and 45 kHz were applied to water, cavitation bubbles were generated and the heat transfer coefficient increased remarkably. When an ultrasonic vibration of 100 kHz was applied, the increase in the heat transfer coefficient was small compared to those at 28 and 45 kHz. At 100 kHz, cavitation was not observed at this low ultrasonic power. The uniformity of heat transfer, which depends on the profile of the standing wave by the ultrasonic vibration, was improved by the method of repeatedly applying multi-vibration.

DOI： 10.1299/kikaib.64.1832

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The characteristic of boiling in a horizonatal channel with changing conditions of heated wall length and channel height have been studied experimentally. Behavior of bubbles on the heated wall and growth of bubble in the channel were observed by high speed camera at the experiment time. As a result, the behavior of growth of bubble which was classified into three types according to channel height had influence on time variation of degree of superheat, heat transfer and burnout heat flux in the channel. When the thickness of liquid on the bottom wall became thin, nucleate boiling with vapor dome was observed on the heated wall.

DOI： 10.1299/kikaib.64.2563

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Language：Japanese   Publisher：一般社団法人日本機械学会  

The heat transfer coefficients during natural convection of water on a downward-facing horizontal surface and that on a vertical surface were measured under the influence of ultrasonic vibration. The multi-type oscillator used in this experiment was able to irradiate in three different frequencies, 28,45 and 100 kHz, not only continuously, but also intermittently. When ultrasonic vibrations of 28 and 45 kHz were applied to water, cavitation bubbles were generated and the heat transfer coefficient increased remarkably. When an ultrasonic vibration of 100 kHz was applied, the increase in the heat transfer coefficient was small compared to those at 28 and 45 kHz. At 100 kHz, cavitation was not observed at this low ultrasonic power. The uniformity of heat transfer, which depends on the profile of the standing wave by the ultrasonic vibration, was improved by the method of repeatedly applying multi-vibration.

DOI： 10.1299/kikaib.64.1832

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Language：Japanese   Publisher：Ehime University  

CiNii Books

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

The characteristic of boiling in a horizonatal channel with changing conditions of heated wall length and channel height have been studied experimentally. Behavior of bubbles on the heated wall and growth of bubble in the channel were observed by high speed camera at the experiment time. As a result, the behavior of growth of bubble which was classified into three types according to channel height had influence on time variation of degree of superheat, heat transfer and burnout heat flux in the channel. When the thickness of liquid on the bottom wall became thin, nucleate boiling with vapor dome was observed on the heated wall.

DOI： 10.1299/kikaib.64.2563

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

The characteristic of boiling in a horizonatal channel with changing conditions of heated wall length and channel height have been studied experimentally. Behavior of bubbles on the heated wall and growth of bubble in the channel were observed by high speed camera at the experiment time. As a result, the behavior of growth of bubble which was classified into three types according to channel height had influence on time variation of degree of superheat, heat transfer and burnout heat flux in the channel. When the thickness of liquid on the bottom wall became thin, nucleate boiling with vapor dome was observed on the heated wall.

DOI： 10.1299/kikaib.64.2563

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DOI： 10.3811/jjmf.12.58

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

When mist flow is injected from a pipe between horizontal parallel disks, a thin liquid film and liquid droplets are left on the lower disk. The behavior of residual liquid on the disk is studied experimentally. The measured front side or back side contact angle of the liquid droplet exposed to air flow does not agree with the advancing or receding contact angle measured by the falling method. The front side and the back side contact angles are concerned with the advancing contact angle, the receding contact angle of the droplet on the wet disk, and the receding contact angle of the droplet on the dry disk. The gas velocity at the stop position of the droplet agrees well with equilibrium velocity calculated from force balance with the front side and the back side contact angles. The analytical equation for calculating the frequency of the sway of the liquid droplet is proposed.

DOI： 10.1299/kikaib.64.1637

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

When mist flow is injected from a jointed pipe vertically between horizontal parallel disks, a liquid film is standing at the specific position on the lower disk. The position of standing liquid film is concerned with the flow between disks. The numerical calculation is performed on the flow using low-Reynolds-number k-ε model. As a result, in the direction of downstream from the position of maximum of pressure gradient on the lower disk, the condition of the flow near the disk changes and intensity of turbulence begins to increase. Comparing with the position of standing liquid film, it is greatly concerned with the condition of the flow near the lower disk.

DOI： 10.1299/kikaib.64.2079

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

When mist flow is injected from a jointed pipe vertically between horizontal parallel disks, a liquid film is standing at the specific position on the lower disk. The position of standing liquid film is concerned with the flow between disks. The numerical calculation is performed on the flow using low-Reynolds-number k-ε model. As a result, in the direction of downstream from the position of maximum of pressure gradient on the lower disk, the condition of the flow near the disk changes and intensity of turbulence begins to increase. Comparing with the position of standing liquid film, it is greatly concerned with the condition of the flow near the lower disk.

DOI： 10.1299/kikaib.64.2079

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

The flow pattern in a channel by ultrasonic vibration has been investigated as a basic research into non-contact fluid control. An ultrasonic transducer is fixed to the center of the bottom of a square test channel, and a standing wave field is formed in this channel. By applying ultrasonic vibration into the flow, cavitation bubbles are generated at the sound pressure antinode in the channel when Re = 2000. Consequently, cavitation bubbles act on the fluid as a barrier causing a separation in the flow and the velocity is reduced locally.

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DOI： 10.1299/kikaib.64.1832

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DOI： 10.20697/jasj.52.8_592

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Language：Japanese   Publisher：一般社団法人日本機械学会  

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Language：Japanese   Publisher：一般社団法人日本機械学会  

The purpose of this report is to predict the cavitation intensity using sound pressure on a heating surface, through experimental investigation and numerical analysis. Sound pressure measured using a small hydrophone was not in accordance with the cavitation intensity because of the difference in acoustic impedance of the hydrophone and water. Nevertheless, the sound pressure calculated by the finitely bounded Green&#039;s function can predict the measured cavitation intensity profile. It is elucidated through this calculation that the larger the sound pressure on the heating surface became, the greater was the cavitation intensity, and that the cavitation intensity on the side wall was far less than that on the bottom.

DOI： 10.1299/kikaib.60.989

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DOI： 10.1299/kikaib.60.989

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

The purpose of this report is to predict the cavitation intensity using sound pressure on a heating surface, through experimental investigation and numerical analysis. Sound pressure measured using a small hydrophone was not in accordance with the cavitation intensity because of the difference in acoustic impedance of the hydrophone and water. Nevertheless, the sound pressure calculated by the finitely bounded Green's function can predict the measured cavitation intensity profile. It is elucidated through this calculation that the larger the sound pressure on the heating surface became, the greater was the cavitation intensity, and that the cavitation intensity on the side wall was far less than that on the bottom. © 1994, The Japan Society of Mechanical Engineers. All rights reserved.

DOI： 10.1299/kikaib.60.989

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DOI： 10.1299/kikaib.59.2232

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

The cavitation intensity and the heat transfer coefficient on the bottom surface of the object, by applying ultrasonic vibration, were measured experimentally. The object faced the ultrasonic generator adhered to the bottom of the water tank. The dimensions of the object were greater than the ultrasonic wavelength. Ultrasonic power of 600 W with a frequency of 40 kHz was used. The cavitation intensity was defined by the erosion loss of aluminum foil, whose thickness was 15 μm, when aluminum foil stuck on the bottom of the object was immersed into water in the ultrasonic field. The result was that the larger the cavitation intensity became, the more the heat transfer coefficient increased. With varying densities of objects, the greater the density was the larger the cavitation intensity.

DOI： 10.1299/kikaib.59.2028

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

The cavitation intensity and the heat transfer coefficient on the bottom surface of the object, by applying ultrasonic vibration, were measured experimentally. The object faced the ultrasonic generator adhered to the bottom of the water tank. The dimensions of the object were greater than the ultrasonic wavelength. Ultrasonic power of 600 W with a frequency of 40 kHz was used. The cavitation intensity was defined by the erosion loss of aluminum foil, whose thickness was 15 μm, when aluminum foil stuck on the bottom of the object was immersed into water in the ultrasonic field. The result was that the larger the cavitation intensity became, the more the heat transfer coefficient increased. With varying densities of objects, the greater the density was the larger the cavitation intensity.

DOI： 10.1299/kikaib.59.2028

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In the present study, two methane hydrate decomposition methods, one using radio frequency wave (RF) and the other microwave (MW) plasma in-liquid, are conducted to investigate in the production of hydrogen the relationship between gas production rate and CH4 conversion ratio. The objective of this research is also to develop a process to use methane hydrate plasma decomposition to produce fuel gas. Thermal decomposition is the dominant method for methane conversion into hydrogen. Using this method, the methane hydrate is broken down and collected as hydrogen gas, with the carbon content left solidified on the ocean floor. For practical application, since electrical power is necessary to generate the plasma, the key is to determine which renewable energy should be incorporated into this system.

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In the present study, two methods for methane hydrate decomposition were conducted, one was using 27.12 MHz radio-frequency plasma jet and another was radio-frequency plasma using a monopole antenna. The objective of this research is to investigate a method to enhance production of hydrogen gas by the plasma from methane hydrate. When the RF plasma irradiated to methane hydrate, the hydrogen production ratio was 42.6% and the hydrogen generation efficiency was 1.9 ml/kJ. On the other hand, the ratio of hydrogen in exhaust gas by the decomposition using plasma jet was decreased with increase of the flow rate from 0 to 150 mL/min. However, when the flow rate was 200 mL/min, the ratio of hydrogen had most greatly 15.6%. The hydrogen generation efficiency tended to be a similar analysis result.

DOI： 10.1299/jsmeted.2014._E143-1_

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DOI： 10.1299/jsmecs.2013.51._1317-1_

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DOI： 10.1299/jsmecs.2013.51._310-1_

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DOI： 10.1299/jsmecs.2013.51._309-1_

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The purpose of this study is to produce hydrogen gas from saccharide efficiently using 27.12 MHz radio-frequency (RF) in-liquid plasma. In order to enhance the production rate of hydrogen gas, ultrasonic irradiation was added to the plasma. The experiments were conducted adopting two different ultrasonic frequencies, 29 kHz using a horn-type transducer and 1.6 MHz using a piezoelectric transducer. When 29 kHz ultrasonic irradiation was added to the RF plasma in 0 to 10wt% glucose solution, the hydrogen production rate increased 4-17% from that without ultrasonic irradiation. When 1.6 MHz ultrasonic irradiation was applied to the RF plasma in 5wt% glucose solution, the gas production rate increased 90-150% from that without ultrasonic irradiation. The effects of ultrasonic atomization and agitation in the solution of nonvolatile glucose enhance a chemical reaction of the in-liquid plasma.

DOI： 10.1299/jsmeted.2013.59

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The purpose of this research is the industrialization of hydrogen production using a commercial microwave oven by generating plasma in waste oil. N-dodecane, engine oil and cooking oil were used as a liquid. N-dodecane can be circulated in the experimental device to assume continuous production of hydrogen. The gas production rate was measured, the content of the produced gas was analyzed. The energy efficiency which was expressed as the ratio of the consumed power for the chemical reaction to the microwave power was calculated. The energy efficiency increased with decrease of the microwave power, and reached 14% at the maximum. To improve the energy efficiency the reaction vessel was decompressed. The gas production rate became approximately 2 times larger and the ratio of hydrogen in the produced gas.

DOI： 10.1299/jsmeted.2012.441

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/jsmecs.2012.50.131701

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DOI： 10.1299/jsmecs.2012.50.131601

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DOI： 10.1299/jsmecs.2012.50.131501

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DOI： 10.1299/jsmecs.2012.50.131401

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DOI： 10.1299/jsmecs.2012.50.30201

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DOI： 10.1299/jsmecs.2012.50.30101

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The purpose of this experiment is conversion of cellulose dispersed in water as fuel using in-liquid plasma. 27.12 MHz high-frequency plasma was generated in aqueous suspension of cellulose powder or aqueous solution of glucose which is monosaccharide. The gas production rate was measured and the components of the gas production were analyzed. When the concentration of cellulose was 40wt% or higher, the production rate became remarkably high because the ball-like aggregation of hydrous cellulose fell into the plasma and the cellulose was decomposed directly by plasma. On the other hand, the glucose and cellulose with 27wt% or lower was decomposed indirectly by plasma, because the emission spectrum from the species which comprises carbon atom was not detected by spectroscopic analysis.

DOI： 10.1299/jsmeted.2012.449

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Language：English   Publisher：JAPAN SOC APPLIED PHYSICS  

The purpose of this research is to develop a process to use the plasma decomposition of clathrate hydrates to produce fuel gas. An ordinary microwave (MW) oven is used as the source of 2.45 GHz MW radiation under atmospheric-pressure. The plasma decomposition of the hydrates could pave the way for a new utilization of atmospheric pressure plasma. Cyclopentane (CP) hydrate formed at atmospheric pressure was decomposed by plasma in a MW oven generating gas with a content of 65% hydrogen, 12% CO, and 8% CO(2). About 7% of the MW input power was consumed to decompose the hydrates. (C) 2011 The Japan Society of Applied Physics

DOI： 10.1143/APEX.4.066201

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DOI： 10.1299/jsmecs.2011.49.187

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/jsmecs.2011.49.423

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DOI： 10.1299/jsmecs.2011.49.425

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DOI： 10.1299/jsmecs.2011.49.437

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Language：Japanese   Publisher：The Heat Transfer Society of Japan  

液体中で亜鉛の電極を利用しマイクロ波プラズマを発生させて電極を原料としたナノ粒子の合成を行った。エタノール中でプラズマを発生させると10-200nmの六角柱または球体の亜鉛ナノ粒子が合成され、純水中で発生させると亜鉛ナノ粒子と酸化亜鉛ナノ粒子が凝集した約200nmの花びら型をした粒子が合成された。また、電極上部に設置された金属プレートの直径と位置を変え、ナノ粒子の合成に及ぼす影響を調べた。ナノ粒子の合成速度は金属プレートの直径が大きいほど、位置が電極先端に近いほど大きくなった。投入電力が230Wの場合、合成速度は5g/hourとなった。さらに、銅の電極を利用し放電開始電力を調べた。放電開始電力は金属プレートの位置が近いほど小さくなった。

DOI： 10.11368/nhts.2011.0.55.0

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本研究では減圧状態から4気圧の圧力範囲で液中プラズマを水中で発生させ，その分光測定から，励起温度，電子密度，ガス温度を求めた．OHの回転温度から得られる液中プラズマの気泡内のガス温度は，圧力の増加につれて高くなり，大気圧下で約3500K，4気圧では約5000Kに達する．液中プラズマはプラズマ自身が熱源となって沸騰する現象である．伝熱面からの沸騰現象では実現が難しい数千Kオーダーの過熱度を持った沸騰現象を液中に容易に発生させることができる．

DOI： 10.11368/nhts.2011.0.284.0

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Language：Japanese   Publisher：The Heat Transfer Society of Japan  

液中プラズマ化学蒸着法におけるダイヤモンドの生成には，基板の材質や基板の表面処理方法が重要である．本研究では基板の材質や表面処理方法を変化させ，液中プラズマ化学蒸着法における適切な基板の材質と表面処理方法の実験を行った．適切な基板の材質と表面処理方法はSiにダイヤモンドパウダーを用いて研磨を行った基板が良好な結果が得られた．また，実験に用いた基板の温度における線膨張係数を比較し，ダイヤが成膜できた基板ではダイヤモンドの線膨張係数の曲線に近いことが分かった．またSiがダイヤモンドの線膨張係数の曲線に最も近似しており最適だと考えられる．

DOI： 10.11368/nhts.2011.0.238.0

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高速度カメラを用いて高周波水中プラズマの励起温度分布の測定を行った．プラズマの発光の様子をダイクロックミラーで波長の違いにより２つの像に分解し，２つの像からバンドパスフィルターによりHαとHβの発光のみを取り出し，並べられた２つの発光の様子を高速度カメラで撮影した．励起温度は２つの発光強度の関係から求められた．励起温度の時間変化はプラズマの周囲の水の蒸発によってできる気泡の生成・成長・離脱の周期と同期した．気泡の離脱直前に励起温度は最大となり温度分布は細長く伸びることが明らかとなった．

DOI： 10.11368/nhts.2011.0.237.0

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DOI： 10.1299/jsmecs.2011.49.441

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

The purpose of this research is to develop a process to use the plasma decomposition of clathrate hydrates to produce fuel gas. An ordinary microwave (MW) oven is used as the source of 2.45 GHz MW radiation under atmospheric-pressure. The plasma decomposition of the hydrates could pave the way for a new utilization of atmospheric pressure plasma. Cyclopentane (CP) hydrate formed at atmospheric pressure was decomposed by plasma in a MW oven generating gas with a content of 65% hydrogen, 12% CO, and 8% CO_2. About 32% of the MW input power was consumed to decompose the hydrate.

DOI： 10.1299/jsmeted.2011.239

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DOI： 10.1299/jsmecs.2010.48.331

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純水中に発生するマイクロ波液中プラズマの点火位置を高速度カメラで観察した。また、3D-FDTD法を用いて電極表面の電界を計算し、マイクロ波によって加熱される液体が吸収する熱量を計算した。この熱量を使って電極周辺の液体の温度計算した結果、プラズマが発生する電極表面の電界強度の最も高い位置と、最も温度が高い位置は必ずしも一致しないことが明らかになった。また、実験から測定したプラズマの点火位置と数値計算によって求めた最も温度の高い地点が一致した。

DOI： 10.11368/nhts.2010.0.31.0

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液体中での高周波やマイクロ波の照射によって発生するプラズマは，周囲の液体を蒸発させることにより，あたかも気泡の中で発生しているように見える．今後，この液中プラズマによる反応場としての利用が期待されている．本研究では，これまで測定されてきた温度分布や電子密度分布，ならびに反応による生成割合等について紹介するとともに，気泡の成長と減衰に関する数値シミュレーションを行い比較する．特に，水素の生成割合が非常に高くなるという実験結果に対して，気泡内の水分解反応と気泡の挙動との関係から明らかにする．

DOI： 10.11368/nhts.2010.0.160.0

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Distributions of emission intensity from radicals, electron temperature and rotational temperature at a radio frequency of 27.12MHz plasma in water are clarified by detailed spectroscopy measurement. Through this investigation, the following were observed. The points of maximum emission intensity of Hα, Hβ, O(777 nm) and O (845 nm) are almost the same, while that of OH shifts upward. The electron temperature decreases, while the rotational temperature increases with pressure. The distribution of the electron temperature changes at a threshold pressure, which is concerned with a change in the electron discharge mechanism. The point of the maximum rotational temperature of OH radicals shifts to approximately 1 mm above that for the maximum intensity of OH emission.

DOI： 10.1299/jsmeted.2009.99

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The purpose of this study is to clear the synthesizing mechanism of the compound materials using plasma CVD method. The determination method of the chemical reaction using the values of electronegativity and ionization energy is presented. The chemical reaction between the atom that has the highest electronegativity and the atom that has the lowest ionization energy occurs with first priority. The calculated results using the method have good agreement with the experimental results of synthesizing materials such as carbon and silicon carbide. Consequently, the method is useful to synthesizing compound semiconductors using plasma CVD method.

DOI： 10.1299/jsmeted.2009.95

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Since in-liquid plasma can be used in a liquid as a chemical reactor, it has an advantage in a treatment technology of a waste liquid and fuel gas production. The purpose of this research is to examine the basic characteristic of in-liquid plasma. In this research, a spectroscope is used for measuring the emission spectra of the in-liquid plasma. In-liquid plasma is generated by applying high-frequency (HF) irradiation of 27.12MHz into a pure water. As for the distribution of the emission intensities, of the emission intensities H and 0 are high in the vicinity of the plasma, where that of OH becomes high in the upper area of the plasma. Electron temperature has a distribution, and becomes the highest at the center of the plasma at 10kPa. The change of the electron temperature in the vertical direction is bigger than that in the horizontal direction. The electron temperature decreases with pressure increases.

DOI： 10.1299/jsmemecjo.2009.3.0_51

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In-liquid plasma has been expected as an advanced technology of generating plasma in a liquid by a high frequency(HF) or a microwave(MW) irradiation. In this study, 27.12MHz HF plasma is generated in pure water as well as in air. The phase difference of voltage and current waveforms before and after plasma ignition, and the self-bias voltage are investigated by using an oscilloscope. The electrical property of plasma as an equivalent circuit can be explained from the difference of the phase difference qualitatively. The self-bias voltage became positive with pressure increase when the electrode made of a tungsten rod is used. As pressure increases, the electron supply into the plasma changes from a secondary electron discharge to thermionic emission.

DOI： 10.1299/jsmemecjo.2009.3.0_49

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DOI： 10.1299/jsmecs.2009.47.121

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DOI： 10.11491/scej.2009.0.414.0

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純水中に高周波を照射する電極を設置し，電極先端でプラズマを発生させる．高速度カメラでプラズマを内包する気泡の挙動を観察する．気泡の生成様式は，水温と供給電力により4つに分類され，加熱沸騰の場合との比較を行った．供給電力に対して，水温の上昇に消費される熱は約90%，蒸発として消費される熱は約10%，気泡表面から水中へと伝導される熱は約30%，さらに，化学反応により消費される熱は1%以下となることがわかった．

DOI： 10.11368/nhts.2009.0.30.0

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The plasma in liquid is generated by applying High-Frequency (HF) irradiation of 27.12 MHz or Microwave (MW) irradiation of 2.45 GHz from an electrode, namely, a monopole-antenna electrode inserted into a reactor vessel, n-dodecane, methanol, and water are used as test liquids. The glow discharge plasma can be kept in spite of atmospheric pressure due to the cooling effect of liquid itself. The light emission from the plasma changes substantially according to the behavior of the bubble. The present Chemical Vapor Deposition (CVD) process also enabled simultaneous production of hydrogen gas and the synthesis of the Carbon Nano-Tubes (CNTs) in hydrocarbon liquids. The actual production of hydrogen per unit energy by this process corresponds to approximately 1% of that by conventional steam reforming method and about 32% of that by the alkaline water electrolysis. Moreover, this process can make the solid carbon of about 14 g/h at the same time. Copyright © 2008 by ASME.

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DOI： 10.1299/jsmecs.2009.47.101

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DOI： 10.1299/jsmecs.2009.47.99

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DOI： 10.1299/jsmecs.2009.47.103

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DOI： 10.11491/scej.2008.0.478.0

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Language：Japanese   Publisher：The Heat Transfer Society of Japan  

本研究の目的は，液中プラズマを市販の電子レンジを用いて発生させ，水素を製造すると同時に，炭素を固定化して，カーボンナノチューブや活性炭などの有用炭化物を生成する方法を開発することである．反応溶液にn-ドデカンを使用しプラズマを発生させと，最大で約純度80％の水素と，メタン，エチレン，アセチレンなどの低級炭化水素が発生する．また，ナノサイズのカーボン粒子，カーボンナノチューブが水素と同時に製造できることを明らかにする．

DOI： 10.11368/nhts.2008.0.218.0

J-GLOBAL

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Language：Japanese  

J-GLOBAL

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Language：Japanese  

J-GLOBAL

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Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.62.2.2.0_213_1

CiNii Books

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/jsmecs.2007.45.219

CiNii Books

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/jsmecs.2007.45.217

CiNii Books

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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J-GLOBAL

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Language：English   Publisher：Ehime University  

Stable plasma can be generated in a liquid hydrocarbon such as n-dodecane or benzene by simultaneous microwave and ultrasonic irradiation. The authors refer to this plasma as "sonoplasma" and distinguish it from "sonoluminescence" on the basis of the continuity of emission. The temperature in the plasma was obtained by measuring two specified emission intensities from the plasma, which reached approximately 5000 K. To analytically estimate the temperature, numerical simulations of the behavior of a single bubble in sound field, taking into account the absorption of microwave energy, were carried out. The temperature inside the bubble in n-dodecane reached approximately 8000 K. In benzene, the temperature inside the bubble, which continued expanding through absorption of microwave energy, exceeded 2000 K.

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Other Link： http://iyokan.lib.ehime-u.ac.jp/dspace/handle/iyokan/1452

Language：Japanese  

J-GLOBAL

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

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Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.61.1.2.0_217_3

CiNii Books

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/jsmecs.2006.44.43

CiNii Books

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J-GLOBAL

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Language：Japanese   Publisher：Steering committee of symposium on ultrasonic electronics  

CiNii Books

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CiNii Books

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers