The Experts below are selected from a list of 15396 Experts worldwide ranked by ideXlab platform
Yoshiyuki Kondo - One of the best experts on this subject based on the ideXlab platform.
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effects of multiple overloads and Hydrogen on high cycle fatigue strength of notched specimen of austenitic stainless steels
Transactions of the Japan Society of Mechanical Engineers. A, 2011Co-Authors: Masanobu Kubota, Toru Sakuma, Junichiro Yamaguchi, Yoshiyuki KondoAbstract:To safely use of Hydrogen Utilization machines after large earthquakes, the effect of multiple overloads and Hydrogen on high-cycle fatigue strength of SUS304 and SUS316L austenitic stainless steels were evaluated. Three kinds of notched fatigue test specimens which have different notch root radius were used. The fatigue strength of both materials was significantly reduced by multiple overloads. The cause was small cracks formed by the overloads. In SUS304, the reduction of fatigue strength became more significant by Hydrogen. The cause was that Hydrogen accelerated propagation of the small cracks during overloading. On the other hand, fatigue strength of SUS316L was insusceptible to Hydrogen. Propagation of the small cracks existing notch root was evaluated by plastic strain range at notch root and Manson-Coffin rule in order to consider application of this study for design.
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The effect of Hydrogen gas environment on fretting fatigue strength of materials used for Hydrogen Utilization machines
Tribology International, 2009Co-Authors: Masanobu Kubota, Yasuhiro Tanaka, Yoshiyuki KondoAbstract:Abstract The objective of this study is the characterization of the fretting fatigue strength in a Hydrogen gas environment. The test materials were a low alloy steel SCM435H, super alloy A286 and two kinds of austenitic stainless steels, SUS304 and SUS316L. The test was performed in Hydrogen gas at 0.12 MPa absolute pressure. The purity of the Hydrogen gas was 99.9999%. The fretting fatigue limit was defined by the fretting fatigue strength at 30 million cycles. For all materials, the fretting fatigue strength in the Hydrogen gas environment increased in the short-life region. However, the fretting fatigue strength in the Hydrogen gas environment decreased in the long-life region when exceeding 10 million cycles except for SCM435H, while there was no reduction in the fretting fatigue strength in air between 10 and 30 million cycles. The reduction rate was 18% for A286, 24% for SUS304 and 7% for SUS316L. The tangential force coefficient in the Hydrogen gas environment increased when compared to that in air. It can be estimated that this increase is one of the causes of the reduced fretting fatigue strength found in a Hydrogen gas environment. In order to discuss the extension of the fretting fatigue life in Hydrogen gas observed at the stress level above the fretting fatigue limit in air, continuous measurement of the fretting fatigue crack propagation was performed in a Hydrogen gas environment using the direct current potential drop method. As a result, it was found that the extension of the fretting fatigue life was caused by the delay in the start of the stable crack propagation.
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effect of absorbed Hydrogen on the near threshold fatigue crack growth behavior of short crack examination on low alloy steel carbon steel and heat resistant alloy a286
Transactions of the Japan Society of Mechanical Engineers. A, 2008Co-Authors: Yoshiyuki Kondo, Masanobu Kubota, Keiko Shishime, Junichiro YamaguchiAbstract:Hydrogen is considered to be a possible energy source in the coming future. However, it has been recognized that Hydrogen has a detrimental effect on the fatigue strength of metal. The fatigue crack growth characteristic is an important property for the integrity assessment of Hydrogen Utilization machine. In this report, the effect of absorbed Hydrogen on the fatigue crack propagation characteristic in the near threshold regime was studied using low alloy steel, carbon steels and heat resistant alloy A286. Especially in this study, very short pre-cracked specimen as small as 0.03 mm deep was used. As a result, materials with Vickers hardness higher than 300 were susceptible to absorbed Hydrogen irrespective of alloy system. Fatigue crack propagation was accelerated and the ΔKth was lowered about 25%. No remarkable change was observed in materials with hardness lower than 200.
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effect of absorbed Hydrogen on the near threshold fatigue crack growth behavior of short crack
Materials Science Forum, 2007Co-Authors: Keiko Shishime, Masanobu Kubota, Yoshiyuki KondoAbstract:Hydrogen is considered to be a possible energy source in the coming future. However, it has been recognized that Hydrogen has a detrimental effect on the fatigue strength of metal. The fatigue crack growth characteristic is an important property for the integrity assessment of Hydrogen Utilization machine. In this report, the effect of Hydrogen on the fatigue crack propagation characteristic was studied using low alloy steel, carbon steels and A286 alloy. Especially in this study, very short pre-cracked specimen as small as 0.03 mm deep was used and the near threshold fatigue crack behavior was studied. As a result, materials whose Vickers hardness was higher than 300 were found to be susceptible to absorbed Hydrogen.
Masanobu Kubota - One of the best experts on this subject based on the ideXlab platform.
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effects of multiple overloads and Hydrogen on high cycle fatigue strength of notched specimen of austenitic stainless steels
Transactions of the Japan Society of Mechanical Engineers. A, 2011Co-Authors: Masanobu Kubota, Toru Sakuma, Junichiro Yamaguchi, Yoshiyuki KondoAbstract:To safely use of Hydrogen Utilization machines after large earthquakes, the effect of multiple overloads and Hydrogen on high-cycle fatigue strength of SUS304 and SUS316L austenitic stainless steels were evaluated. Three kinds of notched fatigue test specimens which have different notch root radius were used. The fatigue strength of both materials was significantly reduced by multiple overloads. The cause was small cracks formed by the overloads. In SUS304, the reduction of fatigue strength became more significant by Hydrogen. The cause was that Hydrogen accelerated propagation of the small cracks during overloading. On the other hand, fatigue strength of SUS316L was insusceptible to Hydrogen. Propagation of the small cracks existing notch root was evaluated by plastic strain range at notch root and Manson-Coffin rule in order to consider application of this study for design.
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effect of Hydrogen absorption on the fatigue strength reduction caused by multiple overloads in notched component
Journal of Solid Mechanics and Materials Engineering, 2010Co-Authors: Masanobu Kubota, Toru Sakuma, Junichiro Yamaguchi, Y. KondoAbstract:Effects of multiple overloads and Hydrogen on high cycle fatigue limit was examined to establish a criterion which assesses whether Hydrogen Utilization machines can be used after large earthquakes. Test materials were SUS304 and SUS316L. The test environments were 0.6MPa Hydrogen gas and air. Hydrogen pre-charged specimen was used for in-Hydrogen gas test. The reduction of fatigue strength was caused by overloads in both materials. The cause of the reduction was small cracks formed by overloads. In SUS304, the reduction of fatigue limit was enhanced by Hydrogen since propagation of small cracks during overloads was accelerated due to Hydrogen. In SUS316L, there was no reduction of fatigue limit due to Hydrogen. Maximum overload amplitude which caused no reduction of fatigue limit was 0.5σ0.2 for SUS304 and 0.75σ0.2 for SUS316L. These values were regarded as the upper limits of overload amplitude below which the continuous use of components are allowed after earthquakes.
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The effect of Hydrogen gas environment on fretting fatigue strength of materials used for Hydrogen Utilization machines
Tribology International, 2009Co-Authors: Masanobu Kubota, Yasuhiro Tanaka, Yoshiyuki KondoAbstract:Abstract The objective of this study is the characterization of the fretting fatigue strength in a Hydrogen gas environment. The test materials were a low alloy steel SCM435H, super alloy A286 and two kinds of austenitic stainless steels, SUS304 and SUS316L. The test was performed in Hydrogen gas at 0.12 MPa absolute pressure. The purity of the Hydrogen gas was 99.9999%. The fretting fatigue limit was defined by the fretting fatigue strength at 30 million cycles. For all materials, the fretting fatigue strength in the Hydrogen gas environment increased in the short-life region. However, the fretting fatigue strength in the Hydrogen gas environment decreased in the long-life region when exceeding 10 million cycles except for SCM435H, while there was no reduction in the fretting fatigue strength in air between 10 and 30 million cycles. The reduction rate was 18% for A286, 24% for SUS304 and 7% for SUS316L. The tangential force coefficient in the Hydrogen gas environment increased when compared to that in air. It can be estimated that this increase is one of the causes of the reduced fretting fatigue strength found in a Hydrogen gas environment. In order to discuss the extension of the fretting fatigue life in Hydrogen gas observed at the stress level above the fretting fatigue limit in air, continuous measurement of the fretting fatigue crack propagation was performed in a Hydrogen gas environment using the direct current potential drop method. As a result, it was found that the extension of the fretting fatigue life was caused by the delay in the start of the stable crack propagation.
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effect of absorbed Hydrogen on the near threshold fatigue crack growth behavior of short crack examination on low alloy steel carbon steel and heat resistant alloy a286
Transactions of the Japan Society of Mechanical Engineers. A, 2008Co-Authors: Yoshiyuki Kondo, Masanobu Kubota, Keiko Shishime, Junichiro YamaguchiAbstract:Hydrogen is considered to be a possible energy source in the coming future. However, it has been recognized that Hydrogen has a detrimental effect on the fatigue strength of metal. The fatigue crack growth characteristic is an important property for the integrity assessment of Hydrogen Utilization machine. In this report, the effect of absorbed Hydrogen on the fatigue crack propagation characteristic in the near threshold regime was studied using low alloy steel, carbon steels and heat resistant alloy A286. Especially in this study, very short pre-cracked specimen as small as 0.03 mm deep was used. As a result, materials with Vickers hardness higher than 300 were susceptible to absorbed Hydrogen irrespective of alloy system. Fatigue crack propagation was accelerated and the ΔKth was lowered about 25%. No remarkable change was observed in materials with hardness lower than 200.
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effect of absorbed Hydrogen on the near threshold fatigue crack growth behavior of short crack
Materials Science Forum, 2007Co-Authors: Keiko Shishime, Masanobu Kubota, Yoshiyuki KondoAbstract:Hydrogen is considered to be a possible energy source in the coming future. However, it has been recognized that Hydrogen has a detrimental effect on the fatigue strength of metal. The fatigue crack growth characteristic is an important property for the integrity assessment of Hydrogen Utilization machine. In this report, the effect of Hydrogen on the fatigue crack propagation characteristic was studied using low alloy steel, carbon steels and A286 alloy. Especially in this study, very short pre-cracked specimen as small as 0.03 mm deep was used and the near threshold fatigue crack behavior was studied. As a result, materials whose Vickers hardness was higher than 300 were found to be susceptible to absorbed Hydrogen.
Fang Zhang - One of the best experts on this subject based on the ideXlab platform.
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in situ Hydrogen Utilization for high fraction acetate production in mixed culture hollow fiber membrane biofilm reactor
Applied Microbiology and Biotechnology, 2013Co-Authors: Fang Zhang, Jing Ding, Nan Shen, Yan Zhang, Zhaowei Ding, Kun Dai, Raymond J ZengAbstract:Syngas fermentation is a promising route for resource recovery. Acetate is an important industrial chemical product and also an attractive precursor for liquid biofuels production. This study demonstrated high fraction acetate production from syngas (H₂ and CO₂) in a hollow-fiber membrane biofilm reactor, in which the Hydrogen utilizing efficiency reached 100% during the operational period. The maximum concentration of acetate in batch mode was 12.5 g/L, while the acetate concentration in continuous mode with a hydraulic retention time of 9 days was 3.6 ± 0.1 g/L. Since butyrate concentration was rather low and below 0.1 g/L, the acetate fraction was higher than 99% in both batch and continuous modes. Microbial community analysis showed that the biofilm was dominated by Clostridium spp., such as Clostridium ljungdahlii and Clostridium drakei, the percentage of which was 70.5%. This study demonstrates a potential technology for the in situ Utilization of syngas and valuable chemical production.
Irini Angelidaki - One of the best experts on this subject based on the ideXlab platform.
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Microbial activity response to Hydrogen injection in thermophilic anaerobic digesters revealed by genome-centric metatranscriptomics
BMC, 2018Co-Authors: Alessandra Fontana, Irini Angelidaki, Panagiotis G. Kougias, Laura Treu, Adam Kovalovszki, Giorgio Valle, Fabrizio Cappa, Lorenzo Morelli, Stefano CampanaroAbstract:Abstract Background The expansion of renewable energy produced by windmills and photovoltaic panels has generated a considerable electricity surplus, which can be utilized in water electrolysis systems for Hydrogen production. The resulting Hydrogen can then be funneled to anaerobic digesters for biogas upgrading (biomethanation) purposes (power-to-methane) or to produce high value-added compounds such as short-chain fatty acids (power-to-chemicals). Genome-centric metagenomics and metatranscriptomic analyses were performed to better understand the metabolic dynamics associated with H2 injection in two different configurations of anaerobic digesters treating acidic wastes, specifically cheese manufacturing byproducts. These approaches revealed the key-genes involved in methanation and carbon fixation pathways at species level. Results The biogas upgrading process in the single-stage configuration increased the CH4 content by 7%. The dominant methanogenic species responsible for the upregulation of the Hydrogenotrophic pathway in this reactor was Methanothermobacter wolfeii UC0008. In the two-stage configuration, H2 injection induced an upregulation of CO2 fixation pathways producing short-chain fatty acids, mainly acetate and butyrate. In this configuration, the abundant species Anaerobaculum Hydrogeniformans UC0046 and Defluviitoga tunisiensis UC0050 primarily upregulated genes related to electron transport chains, suggesting putative syntrophisms with Hydrogen scavenger microbes. Interestingly, Tepidanaerobacter acetatoxydans UC0018 did not act as an acetate-oxidizer in either reactor configurations, and instead regulated pathways involved in acetate production and uptake. A putative syntrophic association between Coprothermobacter proteolyticus UC0011 and M. wolfeii UC0008 was proposed in the two-stage reactor. In order to support the transcriptomic findings regarding the Hydrogen Utilization routes, an advanced bioconversion model was adapted for the simulation of the single- and two-stage reactor setups. Conclusions This is the first study investigating biogas reactor metatranscriptome dynamics following Hydrogen injection for biomethanation and carbon fixation to short-chain fatty acids purposes. The same microbes showed different patterns of metabolic regulation in the two reactor configurations. It was observed an effect of the specialized acidogenic reactor on the overall microbial consortium composition and activity in the two-stage digester. There were also suggested the main species responsible for methanation, short-chain fatty acids production, and electron transport chain mechanisms, in both reactor configurations
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integrated biogas upgrading and Hydrogen Utilization in an anaerobic reactor containing enriched Hydrogenotrophic methanogenic culture
Biotechnology and Bioengineering, 2012Co-Authors: Irini AngelidakiAbstract:Biogas produced by anaerobic digestion, is mainly used in a gas motor for heat and electricity production. However, after removal of CO2, biogas can be upgraded to natural gas quality, giving more Utilization possibilities, such as Utilization as autogas, or distant Utilization by using the existing natural gas grid. The current study presents a new biological method for biogas upgrading in a separate biogas reactor, containing enriched Hydrogenotrophic methanogens and fed with biogas and Hydrogen. Both mesophilic- and thermophilic anaerobic cultures were enriched to convert CO2 to CH4 by addition of H2. Enrichment at thermophilic temperature (55°C) resulted in CO2 and H2 bioconversion rate of 320 mL CH4/(gVSS h), which was more than 60% higher than that under mesophilic temperature (37°C). Different dominant species were found at mesophilic- and thermophilic-enriched cultures, as revealed by PCR–DGGE. Nonetheless, they all belonged to the order Methanobacteriales, which can mediate Hydrogenotrophic methanogenesis. Biogas upgrading was then tested in a thermophilic anaerobic reactor under various operation conditions. By continuous addition of Hydrogen in the biogas reactor, high degree of biogas upgrading was achieved. The produced biogas had a CH4 content, around 95% at steady-state, at gas (mixture of biogas and Hydrogen) injection rate of 6 L/(L day). The increase of gas injection rate to 12 L/(L day) resulted in the decrease of CH4 content to around 90%. Further study showed that by decreasing the gas–liquid mass transfer by increasing the stirring speed of the mixture the CH4 content was increased to around 95%. Finally, the CH4 content around 90% was achieved in this study with the gas injection rate as high as 24 L/(L day). Biotechnol. Bioeng. 2012; 109: 2729–2736. © 2012 Wiley Periodicals, Inc.
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simultaneous Hydrogen Utilization and in situ biogas upgrading in an anaerobic reactor
Biotechnology and Bioengineering, 2012Co-Authors: Gang Luo, Qi Zhou, Sara Johansson, Kanokwan Boe, Li Xie, Irini AngelidakiAbstract:The possibility of converting Hydrogen to methane and simultaneous upgrading of biogas was investigated in both batch tests and fully mixed biogas reactor, simultaneously fed with manure and Hydrogen. Batch experiments showed that Hydrogen could be converted to methane by Hydrogenotrophic methanogenesis with conversion of more than 90% of the consumed Hydrogen to methane. The Hydrogen consumption rates were affected by both P(H₂) (Hydrogen partial pressure) and mixing intensity. Inhibition of propionate and butyrate degradation by Hydrogen (1 atm) was only observed under high mixing intensity (shaking speed 300 rpm). Continuous addition of Hydrogen (flow rate of 28.6 mL/(L/h)) to an anaerobic reactor fed with manure, showed that more than 80% of the Hydrogen was utilized. The propionate and butyrate level in the reactor was not significantly affected by the Hydrogen addition. The methane production rate of the reactor with H₂ addition was 22% higher, compared to the control reactor only fed with manure. The CO₂ content in the produced biogas was only 15%, while it was 38% in the control reactor. However, the addition of Hydrogen resulted in increase of pH (from 8.0 to 8.3) due to the consumption of bicarbonate, which subsequently caused slight inhibition of methanogenesis.
David Scott - One of the best experts on this subject based on the ideXlab platform.
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Hydrogen based industry from remote excess hydroelectricity
International Journal of Hydrogen Energy, 1997Co-Authors: N. Ouellette, Hans-holger Rogner, David ScottAbstract:Abstract This paper examines synergies, opportunities and barriers associated with Hydrogen and excess hydroelectricity in remote areas. The work is based on a case study that examined the techno-economic feasibility of a new Hydrogen-based industry using surplus/off-peak generating capacity of the Taltson Dam and Generating Station in the Northwest Territories, Canada. After evaluating the amount and cost of Hydrogen that could be produced from the excess capacity, the study investigates three Hydrogen Utilization scenarios: (1) merchant liquid or compressed Hydrogen, (2) Hydrogen as a chemical feedstock for the production of Hydrogen peroxide, (3) methanol production from biomass, oxygen and Hydrogen. Hydrogen peroxide production is the most promising and attractive strategy in the Fort Smith context. The study also illustrates patterns that recur in isolated sites throughout the world.
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Hydrogen from remote excess hydroelectricity. Part II: Hydrogen peroxide or biomethanol
International Journal of Hydrogen Energy, 1995Co-Authors: N. Ouellette, Hans-holger Rogner, David ScottAbstract:Abstract This paper examines synergies, opportunities and barriers associated with electrolytic Hydrogen production from excess hydroelectricity in remote areas. The work is based on a case study that examined the techno-economic feasibility of a new Hydrogen-based industry using surplus/off-peak generating capacity of the Taltson Dam and Generating Station in Fort Smith, Northwest Territories, Canada. A first study evaluated the amount and cost of Hydrogen that could be produced from the excess capacity. This study investigates two Hydrogen Utilization scenarios: Hydrogen as a chemical feedstock for the production of Hydrogen peroxide, and methanol production from biomass, oxygen and Hydrogen. Hydrogen peroxide production represents the most promising and attractive Hydrogen Utilization option.
