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排序方式: 共有1645条查询结果,搜索用时 15 毫秒
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Like Yue Shixue Wang Takuto Araki Yoshio Utaka Yulin Wang 《International Journal of Hydrogen Energy》2021,46(3):2969-2977
Water management of proton exchange membrane fuel cells remains a prominent issue in research concerning fuel cells. In this study, the gas diffusion layer (GDL) of a fuel cell is partially treated with a hydrophobic agent, and the effect of GDL hydrophobicity on the water distribution in the fuel cell is examined. First, the effect of the position of the cathode GDL hydrophobic area relative to the channel on the fuel cell performance is investigated. Then, the water distribution in the fuel cell cathode GDL is observed using X-ray imaging. The experimental results indicate that when the hybrid GDL's hydrophobic area lies on the channel, water tends to accumulate under the rib, and the water content in the channel is low; this improves the fuel cell performance. When the hydrophobic area is under the rib, the water distribution is more uniform, but the performance deteriorates. 相似文献
3.
Russian Journal of Non-Ferrous Metals - In this study, the micro-mechanisms involved in fatigue crack propagation are investigated qualitatively in a Al/Al2O3/SiC hybrid metal matrix composite... 相似文献
4.
Ludi Xu Degui Zhu Yunlong Liu Tohru S. Suzuki Byung-nam Kim Yoshio Sakka Salvatore Grasso Chunfeng Hu 《Journal of the European Ceramic Society》2018,38(10):3417-3423
Oxidation resistance of textured Ti3AlC2 ceramics was measured in the temperature range 1273–1573?K. It was found that the oxidation was markedly anisotropic and the samples exhibited a better oxidation resistance when tested along a direction transverse to the c-axis. This behavior was attributed to the rapid diffusion of Al within its basal planes to form a passivating Al2O3 scale and it respected Ellingham diagrams. The scales formed had different compositions depending on the testing direction; this response was clearly resulting from the crystallographic orientation. Even at 1473?K after 20?h exposure, the samples tested in a direction transverse to the c-axis showed a reduced weight gain which was 45 times lower than one seen on a basal plane. 相似文献
5.
Koji Morita Byung-Nam Kim Hidehiro Yoshida Keijiro Hiraga Yoshio Sakka 《Journal of the European Ceramic Society》2018,38(6):2588-2595
Carbon contamination from the carbon paper/dies during spark-plasma-sintering (SPS) processing was examined in the MgAl2O4 spinel. The carbon contamination sensitively changes with the heating rate during the SPS processing. At the high heating rate of 100 °C/min, the carbon contamination having organized structures occurred over almost the entire area from the surface to deep inside the SPSed spinel disk. In contrast, at the slow heating rate of 10 °C/min, the carbon contamination having disordered structures occurred only around the surface area. The carbon phases transform into high pressure CO/CO2 gases by post-annealing in air and lead to pore formation along the grain junctions. The pore formation significantly occurs at the high heating rate due to the large amount of the contaminant carbon phases. This suggests that if once the carbon contamination was formed in the materials, it is very difficult to remove the carbon phases from the materials. 相似文献
6.
Kitaoka Haru Amano Ken-ichi Nishi Naoya Sakka Tetsuo 《Optimization and Engineering》2022,23(2):1033-1055
Optimization and Engineering - The Nelder-Mead (NM) method is a popular derivative-free optimization algorithm owing to its fast convergence and robustness. However, it is known that the method... 相似文献
7.
Yoshio Kimura 《Papers in Regional Science》1985,56(1):167-176
The purpose of this paper is to shed new light on the consistent aggregation problem in input-output systems by making use of some properties ofM-matrices. For example, we show that the stability of a multisectoral dynamic multiplier model is invariant under consistent aggregation, that a consistently aggregated dynamic Leontief model is relatively stable if the original system is stable, and that Gillen and Guccione's Third Proposition can be generalized to cover the case of weighted aggregation. 相似文献
8.
Stefano Ambrogio Blanka Magyari-Köpe Nicolas Onofrio Md Mahbubul Islam Dan Duncan Yoshio Nishi Alejandro Strachan 《Journal of Electroceramics》2017,39(1-4):39-60
Resistance switching devices based on electrochemical processes have attractive significant attention in the field of nanoelectronics due to the possibility of switching in nanosecond timescales, miniaturization to tens of nanometer and multi-bit storage. Their deceptively simple structures (metal-insulator-metal stack) hide a set of complex, coupled, processes that govern their operation, from electrochemical reactions at interfaces, diffusion and aggregation of ionic species, to electron and hole trapping and Joule heating. A combination of experiments and modeling efforts are contributing to a fundamental understanding of these devices, and progress towards a predictive understanding of their operation is opening the possibility for the rational optimization. In this paper we review recent progress in modeling resistive switching devices at multiple scales; we briefly describe simulation tools appropriate at each scale and the key insight that has been derived from them. Starting with ab initio electronic structure simulations that provide an understanding of the mechanisms of operation of valence change devices pointing to the importance of the aggregation of oxygen vacancies in resistance switching and how dopants affect performance. At slightly larger scales we describe reactive molecular dynamics simulations of the operation of electrochemical metallization cells. Here the dynamical simulations provide an atomic picture of the mechanisms behind the electrochemical formation and stabilization of conductive metallic filaments that provide a low-resistance path for electronic conduction. Kinetic Monte Carlo simulations are one step higher in the multiscale ladder and enable larger scale simulations and longer times, enabling, for example, the study of variability in switching speed and resistance. Finally, we discuss physics-based simulations that accurately capture subtleties of device behavior and that can be incorporated in circuit simulations. 相似文献
9.
Inside Cover: Molecular Design of an Environmentally Sensitive Fluorescent Nucleoside, 3‐Deaza‐2′‐Deoxyadenosine Derivative: Distinguishing Thymine by Probing the DNA Minor Groove (ChemBioChem 11/2014) 下载免费PDF全文
10.
Qian Wang Chunfeng Hu Shu Cai Yoshio Sakka Salvatore Grasso Qing Huang 《International Journal of Applied Ceramic Technology》2014,11(5):911-918
High‐purity ternary laminated compound Ti3SiC2 was successfully synthesized by a microwave heating method in the flowing argon for the first time. The mixtures of titanium, silicon, and graphitic carbon (Cgc) or activated carbon (Cac) with different molar ratios were used to investigate the reaction mechanisms. It was confirmed that Ti3SiC2 with high purity of 98 vol.% was achieved without the aids of Al. The optimum experimental parameters were determined as Ti/Si/Cgc having the molar ratio of 3/2.2/2, first holding at 1480°C for 30 min, and subsequent dwelling at 1300°C for 60 min. 相似文献