H. Itoga, T. Matsuo, Akihiro Orita, H. Matsunaga, S. Matsuoka
The susceptibility to hydrogen embrittlement of two types of high strength austenitic stainless steels containing a small amount nitrogen and niobium were investigated by conducting a series of slow strain rate tests (SSRT) and fatigue crack growth tests in hydrogen gas with a pressure of around 100 MPa. The JIS-SUS304 and JIS-SUS316L austenitic stainless steels were also tested for a comparative purpose. In JIS-SUS304, the tensile strength and reduction of area in hydrogen gas were much lower than those in air. In contrast, in JIS-SUS316L, the degradation of those tensile properties in hydrogen gas was not so significant. The high strength austenitic stainless steels also exhibited an excellent resistance both in tensile strength and ductility in hydrogen gas. In JIS-SUS304, the fatigue crack growth in hydrogen gas was 10 times as fast as that in air, while the factor of acceleration remained within 1.5 3 in JIS-SUS316L and the high strength austenitic stainless steels. It was presumed that, in those high strength austenitic stainless steels, a small amount of added elements, N and Nb, increased the strength level as well as the stability of austenitic phase, which thereby led to the excellent resistance against hydrogen embrittlement.
{"title":"SSRT and fatigue crack growth properties of two types of high strength austenitic stainless steels in high pressure hydrogen gas","authors":"H. Itoga, T. Matsuo, Akihiro Orita, H. Matsunaga, S. Matsuoka","doi":"10.1299/KIKAIA.79.1726","DOIUrl":"https://doi.org/10.1299/KIKAIA.79.1726","url":null,"abstract":"The susceptibility to hydrogen embrittlement of two types of high strength austenitic stainless steels containing a small amount nitrogen and niobium were investigated by conducting a series of slow strain rate tests (SSRT) and fatigue crack growth tests in hydrogen gas with a pressure of around 100 MPa. The JIS-SUS304 and JIS-SUS316L austenitic stainless steels were also tested for a comparative purpose. In JIS-SUS304, the tensile strength and reduction of area in hydrogen gas were much lower than those in air. In contrast, in JIS-SUS316L, the degradation of those tensile properties in hydrogen gas was not so significant. The high strength austenitic stainless steels also exhibited an excellent resistance both in tensile strength and ductility in hydrogen gas. In JIS-SUS304, the fatigue crack growth in hydrogen gas was 10 times as fast as that in air, while the factor of acceleration remained within 1.5 3 in JIS-SUS316L and the high strength austenitic stainless steels. It was presumed that, in those high strength austenitic stainless steels, a small amount of added elements, N and Nb, increased the strength level as well as the stability of austenitic phase, which thereby led to the excellent resistance against hydrogen embrittlement.","PeriodicalId":331123,"journal":{"name":"Transactions of the Japan Society of Mechanical Engineers. B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114780229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, a renewal planning problem of energy supply system is formulated as a large scale mixed-integer linear programming problem, in which the objective function to the minimized is the average value of annual total cost during system’s evaluation period. By adopting the programming language AMPL and CPLEX solver, a numerical study is carried out for a hospital, where electrical(e.g., heat pump) and gas(e.g., gas engine cogeneration) systems are compared together with arbitrary combination one, which is composed of electrical and gas driven pieces of equipment, by focusing particularly on the influence of initial system’s difference. The main results obtained are as follows: (a) If the initial system is gas one, it is better to renew it to the electrical one as soon as possible due to relatively low energy efficiency of gas utilizing pieces of equipment, the high price of gas input energy and so on. (b) If the initial system is electrical one, the optimal renewal year becomes relatively later year, because it is economically better to use the initially installed high efficiency system as long as possible. (c) Theoretically, the arbitrary combination system is of course the best renewal one. However, there is no economic difference between the arbitrary combination system and the electrical one.
{"title":"Influence of Initial Systems on the Renewal Planning of Energy Supply Systems for a Hospital","authors":"S. Yoshida, Akira Yoshida, Koichi Ito, Y. Amano","doi":"10.1299/KIKAIB.79.2312","DOIUrl":"https://doi.org/10.1299/KIKAIB.79.2312","url":null,"abstract":"In this study, a renewal planning problem of energy supply system is formulated as a large scale mixed-integer linear programming problem, in which the objective function to the minimized is the average value of annual total cost during system’s evaluation period. By adopting the programming language AMPL and CPLEX solver, a numerical study is carried out for a hospital, where electrical(e.g., heat pump) and gas(e.g., gas engine cogeneration) systems are compared together with arbitrary combination one, which is composed of electrical and gas driven pieces of equipment, by focusing particularly on the influence of initial system’s difference. The main results obtained are as follows: (a) If the initial system is gas one, it is better to renew it to the electrical one as soon as possible due to relatively low energy efficiency of gas utilizing pieces of equipment, the high price of gas input energy and so on. (b) If the initial system is electrical one, the optimal renewal year becomes relatively later year, because it is economically better to use the initially installed high efficiency system as long as possible. (c) Theoretically, the arbitrary combination system is of course the best renewal one. However, there is no economic difference between the arbitrary combination system and the electrical one.","PeriodicalId":331123,"journal":{"name":"Transactions of the Japan Society of Mechanical Engineers. B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131500682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We have developed a novel nanoscale patterning method of self-assembled monolayer (SAM) using near-field light. This method utilizes the thermal desorption of constituent molecules of a SAM (e.g. the desorption temperature of Octadecanethiol on Au is 130~230 o C) through the irradiation with near-field light, which can make noncontact and noncontaminating patterning of the SAM at nanoscale. In this paper, the near-field photothermal effect is numerically analyzed by the finite difference time domain (FDTD) method, and the electromagnetic field intensity and temperature distributions are estimated. The sample consists of Au thin film as a bonding layer with thiolated molecules of SAM, Ti thin film as an adhesion layer for Au, and SiO 2 substrate. In the analysis, the shape of the near-field optical fiber probe and the thickness of the thin film layer are considered. In the case of the thick Au layer with a double-tapered near-field optical fiber probe, the temperature of the fiber-tip becomes higher than that of Au surface. The strong heating of the probe tip causes a fatal damage of the coating metal of the fiber, therefore it is difficult to couple the high intensity laser into the near-field optical fiber probe in order to reach the desorption temperature. On the other hand, the desorption temperature can be achieved with the 10 nm-thick Au thin film. Moreover, in order to gain high optical intensity enhancements, the triple-tapered near-field optical fiber probe is utilized. Our simulations confirm extremely high temperature distribution on the sample surface by using the triple-tapered near-field optical fiber probe with 10 nm-thick Au thin film layer on 50 nm-thick
{"title":"Fdtd analysis of nanoscale temperature distribution induced by near-Field photothermal effect","authors":"Shouhei Fukuyama, Y. Taguchi","doi":"10.1299/KIKAIB.79.2254","DOIUrl":"https://doi.org/10.1299/KIKAIB.79.2254","url":null,"abstract":"We have developed a novel nanoscale patterning method of self-assembled monolayer (SAM) using near-field light. This method utilizes the thermal desorption of constituent molecules of a SAM (e.g. the desorption temperature of Octadecanethiol on Au is 130~230 o C) through the irradiation with near-field light, which can make noncontact and noncontaminating patterning of the SAM at nanoscale. In this paper, the near-field photothermal effect is numerically analyzed by the finite difference time domain (FDTD) method, and the electromagnetic field intensity and temperature distributions are estimated. The sample consists of Au thin film as a bonding layer with thiolated molecules of SAM, Ti thin film as an adhesion layer for Au, and SiO 2 substrate. In the analysis, the shape of the near-field optical fiber probe and the thickness of the thin film layer are considered. In the case of the thick Au layer with a double-tapered near-field optical fiber probe, the temperature of the fiber-tip becomes higher than that of Au surface. The strong heating of the probe tip causes a fatal damage of the coating metal of the fiber, therefore it is difficult to couple the high intensity laser into the near-field optical fiber probe in order to reach the desorption temperature. On the other hand, the desorption temperature can be achieved with the 10 nm-thick Au thin film. Moreover, in order to gain high optical intensity enhancements, the triple-tapered near-field optical fiber probe is utilized. Our simulations confirm extremely high temperature distribution on the sample surface by using the triple-tapered near-field optical fiber probe with 10 nm-thick Au thin film layer on 50 nm-thick","PeriodicalId":331123,"journal":{"name":"Transactions of the Japan Society of Mechanical Engineers. B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132347467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Polymer electrolyte fuel cell (PEFC) is expected to be used with the power sources for the automobile and the cogeneration power source for home and so forth. At the cathode-side of a PEFC, oxygen is transported as the reactant gas from gas channel through gas diffusion layer (GDL) to the catalyst layer. However, the large quantity of moisture is generated under the situation of the high power generation. Since, as a result, the moisture blocks transporting oxygen, the cell voltage falls off drastically. The objective of this study is to improve the management of moisture from GDL in gas channels of separator for PEFC. The oblique micro-grooves are manufactured inside gas channel walls. Water from GDL is discharged through the micro-grooves to upper-side of gas channel by surface tension and shearing force generated by air flow. Velocity of water flowing in the micro-grooves was measured by using the laser induced fluorescence method. It was confirmed experimentally that micro-grooves manufactured inside gas channel worked properly, that is, water discharge from GDL to upper-side of channel was succeeded. The water velocity and effective length of micro-grooves to remove water from GDL surface increased with the decrease in inclination angle θ of micro-grooves in this experimental range of θ =20~40 ° . It was shown that the effective length of approximately 200mm, which was overall length of experimental apparatus, was attained.
{"title":"Improvement of water discharge from gas diffusion layer to gas channel with obliquely-directed micro-grooves arranged inside channel walls","authors":"A. Okabe, Y. Utaka","doi":"10.1299/KIKAIB.79.1866","DOIUrl":"https://doi.org/10.1299/KIKAIB.79.1866","url":null,"abstract":"Polymer electrolyte fuel cell (PEFC) is expected to be used with the power sources for the automobile and the cogeneration power source for home and so forth. At the cathode-side of a PEFC, oxygen is transported as the reactant gas from gas channel through gas diffusion layer (GDL) to the catalyst layer. However, the large quantity of moisture is generated under the situation of the high power generation. Since, as a result, the moisture blocks transporting oxygen, the cell voltage falls off drastically. The objective of this study is to improve the management of moisture from GDL in gas channels of separator for PEFC. The oblique micro-grooves are manufactured inside gas channel walls. Water from GDL is discharged through the micro-grooves to upper-side of gas channel by surface tension and shearing force generated by air flow. Velocity of water flowing in the micro-grooves was measured by using the laser induced fluorescence method. It was confirmed experimentally that micro-grooves manufactured inside gas channel worked properly, that is, water discharge from GDL to upper-side of channel was succeeded. The water velocity and effective length of micro-grooves to remove water from GDL surface increased with the decrease in inclination angle θ of micro-grooves in this experimental range of θ =20~40 ° . It was shown that the effective length of approximately 200mm, which was overall length of experimental apparatus, was attained.","PeriodicalId":331123,"journal":{"name":"Transactions of the Japan Society of Mechanical Engineers. B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128870817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Nagashima, S. Tsuda, N. Tsuboi, M. Koshi, A. Hayashi, T. Tokumasu
In this paper, we conducted analysis of p-V-T relation of cryogenic hydrogen using classical Molecular Dynamics (MD) and path integral Centroid MD (CMD) method to understand an effect of quantum nature of hydrogen molecules. We performed NVE constant MD simulation across a wide density-temperature region to obtain an Equation Of State (EOS). Simulation results were compared with experimental data. As a result, it was confirmed that classical MD cannot reproduce the experimental data at the high density region. On the other hand, CMD well reproduces the thermodynamic properties of liquid hydrogen. Moreover, it was clarified that taking the quantum effect into account makes repulsion force larger and the potential well smaller. Because of this mechanism, the intermolecular interaction of hydrogen diminishes and the virial pressure increases.
{"title":"An analysis of quantum effect on the p-V-T relation of cryogenic hydrogen using centroid molecular dynamics method","authors":"H. Nagashima, S. Tsuda, N. Tsuboi, M. Koshi, A. Hayashi, T. Tokumasu","doi":"10.1299/KIKAIB.79.1848","DOIUrl":"https://doi.org/10.1299/KIKAIB.79.1848","url":null,"abstract":"In this paper, we conducted analysis of p-V-T relation of cryogenic hydrogen using classical Molecular Dynamics (MD) and path integral Centroid MD (CMD) method to understand an effect of quantum nature of hydrogen molecules. We performed NVE constant MD simulation across a wide density-temperature region to obtain an Equation Of State (EOS). Simulation results were compared with experimental data. As a result, it was confirmed that classical MD cannot reproduce the experimental data at the high density region. On the other hand, CMD well reproduces the thermodynamic properties of liquid hydrogen. Moreover, it was clarified that taking the quantum effect into account makes repulsion force larger and the potential well smaller. Because of this mechanism, the intermolecular interaction of hydrogen diminishes and the virial pressure increases.","PeriodicalId":331123,"journal":{"name":"Transactions of the Japan Society of Mechanical Engineers. B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128391012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"圧縮機の吐出用リード弁における開き遅れ挙動の計算（弁変形-ガス流れ-油膜流れ連成計算のためのモデル化）","authors":"文太 吉住, 靖裕 近藤, 隆宏 諸井, 真司 玉野, 洋平 森西","doi":"10.1299/KIKAIB.79.1985","DOIUrl":"https://doi.org/10.1299/KIKAIB.79.1985","url":null,"abstract":"","PeriodicalId":331123,"journal":{"name":"Transactions of the Japan Society of Mechanical Engineers. B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133345502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kenichiro Nagat, Yutaro Suzuki, Ytizo Inokuchi, H. Oinuma, Tatsuya Ishll, N. Yamasaki
The main objective of this study is to apply active noise cancellation technique to the duct fan. In the acoustic field of a duct fan, the rotating acoustic modes are generated due to the interaction of stators and rotating blades. To achieve the essential elimination of dominant acoustic modes inside the duct, the accurate acoustic mode decomposition and the reproduction of anti-noise are both required. We build a real-time acoustic mode decomposition system with an array of microphones circumferentially mounted on the duct surface. The filtered-x LMS algorithm in the frequency domain form is developed with applying the result of mode decomposition as an error signal in order to achieve the elimination of a specific acoustic mode. An array of loudspeakers is equipped circumferentially onto the duct to generate “anti-noise” signal. A large noise reduction and rapid convergence with this method have been shown by the results.
{"title":"Active noise cancellation of ducted fan using real-time acoustic modal analysis","authors":"Kenichiro Nagat, Yutaro Suzuki, Ytizo Inokuchi, H. Oinuma, Tatsuya Ishll, N. Yamasaki","doi":"10.1299/KIKAIB.79.739","DOIUrl":"https://doi.org/10.1299/KIKAIB.79.739","url":null,"abstract":"The main objective of this study is to apply active noise cancellation technique to the duct fan. In the acoustic field of a duct fan, the rotating acoustic modes are generated due to the interaction of stators and rotating blades. To achieve the essential elimination of dominant acoustic modes inside the duct, the accurate acoustic mode decomposition and the reproduction of anti-noise are both required. We build a real-time acoustic mode decomposition system with an array of microphones circumferentially mounted on the duct surface. The filtered-x LMS algorithm in the frequency domain form is developed with applying the result of mode decomposition as an error signal in order to achieve the elimination of a specific acoustic mode. An array of loudspeakers is equipped circumferentially onto the duct to generate “anti-noise” signal. A large noise reduction and rapid convergence with this method have been shown by the results.","PeriodicalId":331123,"journal":{"name":"Transactions of the Japan Society of Mechanical Engineers. B","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126953112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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