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991.
Primary Li-air cell development 总被引:1,自引:0,他引:1
Owen Crowther Benjamin MeyerMichael Morgan Mark Salomon 《Journal of power sources》2011,196(3):1498-1502
In the present communication, we report on recent researches for optimizing the performance of a primary organic-based Li-air cell. These researches focus on new processing technologies for a high capacity and high rate capable carbon cathode, and the development of oxygen selective membranes based on polysiloxane and methacrylate-polysiloxane copolymers. These membranes, generally classified as silicone rubbers exhibit high permeability for oxygen and impede water transport from the atmosphere into the Li-air cell and solvent loss from the cell into the atmosphere. 相似文献
992.
Paul C.-P. Chao Pen-Yen Liao Meng-Yen Tsai Chin-Teng Lin 《Microsystem Technologies》2011,17(5-7):1009-1023
This study performs precision positioning of a generic piezoelectric structure against hysteresis effects by finite elements, microscopic hysteresis cancellation and robust H ?? compensation. The designed control algorithm is expected to be effective in enhancing servo performance of hard disk drives. The precision positioning is accomplished by adding a polarization term into the linear constitutive equations of piezoelectric materials. This polarization term is then described by the well-known Preisach model. Applying basic principles of finite elements and Hamilton??s thoery, the macroscopic governing equations of an arbitrary piezoelectric system in finite elements are obtained. Based on the macro-model, a controller consisting of two parts is designed to perform the precision positioning of a generic piezo-structure. The first part is responsible for direct hysteresis cancellation at the microscopic level, while the second one is a robust H ?? controller to overcome inevitable cancellation errors. In this way, the control effort is then more effective than the conventional PI and double-lead controller without microscopic hysteresis cancellation. A simple piezoelectric structure of a bender-bimorph cantilever beam is considered for designs and experimental validation. Based on experimental results, the proposed control design is found effective to suppress hysteresis effects as opposed to conventional controllers. 相似文献
993.
In situ metal ion contamination and the effects on proton exchange membrane fuel cell performance 总被引:1,自引:0,他引:1
Mark Sulek Jim AdamsSteve Kaberline Mark RickettsJames R. Waldecker 《Journal of power sources》2011,196(21):8967-8972
Automotive fuel cell technology has made considerable progress, and hydrogen fuel cell vehicles are regarded as a possible long-term solution to reduce carbon dioxide emissions, reduce fossil fuel dependency and increase energy efficiency. Even though great strides have been made, durability is still an issue. One key challenge is controlling MEA contamination. Metal ion contamination within the membrane and the effects on fuel cell performance were investigated. Given the possible benefits of using stainless steel or aluminum for balance-of-plant components or bipolar plates, cations of Al, Fe, Ni and Cr were studied. Membranes were immersed in metal sulfide solutions of varying concentration and then assembled into fuel cell MEAs tested in situ. The ranking of the four transition metals tested in terms of the greatest reduction in fuel cell performance was: Al3+ ? Fe2+ > Ni2+, Cr3+. For iron-contaminated membranes, no change in cell performance was detected until the membrane conductivity loss was greater than approximately 15%. 相似文献
994.
Gao Zesong Zhang Xinhua Tan Yitong Yang Dong Ma Linrui Shen Jianjia Liao Qiangqiang 《Protection of Metals and Physical Chemistry of Surfaces》2021,57(3):570-578
Protection of Metals and Physical Chemistry of Surfaces - Anticorrosive conductive coatings were prepared by adding solvents, dispersants, nickel powders, etc. to acrylic resin coatings with high... 相似文献
995.
996.
以45钢为基材,通过放电等离子烧结和铸造工艺成功制备了WC颗粒增强表层复合材料,研究不同浇铸工艺参数对表层WC/Fe复合材料与基材之间的界面结合及微观组织的影响。结果表明:随着浇铸量的增加,锭模的数值模拟温度可达1493 ℃,高温停留时间约734 s,为实现钢液与WC/Fe复合材料冶金结合提供有利条件,但是过高的浇铸量使WC/Fe复合材料的组织发生明显的变化,几乎观察不到WC增强相,组织出现大量鱼骨状碳化物Fe3W3C。当浇铸量控制在锭模体积的2/5时,可得到良好的WC/Fe复合材料与基材的宏观界面,界面反应产物Fe3W3C增加,但是增强颗粒仍保留了浇铸前的原始形貌。 相似文献
997.
Heath H. Himstedt Mark S. Huberty Alon V. McCormick Lanny D. Schmidt E. L. Cussler 《American Institute of Chemical Engineers》2015,61(4):1364-1371
Conversion to ammonia with Haber–Bosch catalysts can be increased above 95% by selective absorption of ammonia by MgCl2. The maximum conversion depends on reaction and absorption equilibria. At very short times, the measured conversion rate is the same with and without absorption by the MgCl2 salt; the overall rate constants are comparable to those in the literature. At larger times, conversion to ammonia can be over seven times greater with MgCl2 than without. However, the overall rate constants can be over 10 times slower because they are controlled by ammonia diffusion in the solid salt. An approximate, pseudosteady state theory consistent with these results provides a strategy for improving the overall rate while keeping the conversion over 90%. For example, the absorption rates might be increased using smaller particles of absorbent on a porous inert absorbent support. The results provide part of the basis for designing small scale ammonia plants. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1364–1371, 2015 相似文献
998.
Bor‐Sen Chiou Diana Valenzuela‐Medina Mark Wechsler Cristina Bilbao‐Sainz Artur K. Klamczynski Tina G. Williams Delilah F. Wood Greg M. Glenn William J. Orts 《应用聚合物科学杂志》2015,132(10)
Torrefied almond shells and wood chips were incorporated into polypropylene as fillers to produce torrefied biomass‐polymer composites. The composites were prepared by extrusion and injection molding. Response surface methodology was used to examine the effects of filler concentration, filler size, and lignin factor (relative lignin to cellulose concentration) on the material properties of the composites. The heat distortion temperatures, thermal properties, and tensile properties of the composites were characterized by thermomechanical analysis, differential scanning calorimetry, and tensile tests, respectively. The torrefied biomass composites had heat distortion temperatures of 8–24°C higher than that of neat polypropylene. This was due to the torrefied biomass restricting mobility of polypropylene chains, leading to higher temperatures for deformation. The incorporation of torrefied biomass generally resulted in an increase in glass transition temperature, but did not affect melting temperature. Also, the composites had lower tensile strength and elongation at break values than those of neat polypropylene, indicating weak adhesion between torrefied biomass and polypropylene. However, scanning electron microscopy results did indicate some adhesion between torrefied biomass and polypropylene. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41582. 相似文献
999.
Extraction,Composition and Functional Properties of Pennycress (Thlaspi arvense L.) Press Cake Protein
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Mila P. Hojilla‐Evangelista Gordon W. Selling Mark A. Berhow Roque L. Evangelista 《Journal of the American Oil Chemists' Society》2015,92(6):905-914
This study compared two methods for extracting the protein in pennycress (Thlaspi arvense L.) press cake and determined the composition and functional properties of the protein products. Proteins in pennycress press cake were extracted by using the conventional alkali‐solubilization–acid‐precipitation (AP) method or saline‐based (SE) procedure (0.1 M NaCl at 50 °C). The extraction method has a major influence on the purity and functional properties of press cake protein products. AP had a lower protein yield (23 %) but much higher purity (90 % crude protein) compared with SE (45 % yield, 67 % crude protein). AP protein isolate had high foam capacity (120 ml), high foam stability (96 % foam volume retention) and high emulsion stability (24–35 min), and it was resistant to heat denaturation (3 % loss of solubility at pH 2 and pH 10). On the other hand, SE protein concentrate showed remarkably high solubility (>76 %) between pH 2 and 10 and exceptional emulsifying activity (226–412 m2/g protein), but was more susceptible to heat denaturation at pH 7 and pH 10 (65–78 % loss of solubility). These results strongly demonstrate that higher purity pennycress press cake protein can be produced by either saline extraction or acid precipitation and have functional properties that are desirable for non‐food uses. 相似文献
1000.
Feixiang Liu Ganggang Cao Zhengbing Guan Xiangru Liao Yujie Cai 《Journal of the American Oil Chemists' Society》2015,92(1):55-63
Cottonseed meal (CSM), a common agricultural by‐product, was used as a nutrient source for the production of eicosapentaenoic acid (EPA) by Pythium irregulare. CSM can support good cell growth performance, as can yeast extract (YE). In terms of the maximum EPA content and EPA yield, CSM is superior to YE. Low concentrations of CSM are beneficial to lipid synthesis, and high concentrations favor the EPA content. Utilizing response surface methodology (RSM) analysis, the optimum contents of glucose and CSM in the fermentation medium were determined to be 40.2 and 16.1 g/l, respectively. After 6 days of fermentation at 25 °C and optimal conditions, the EPA yield and productivity were 245.3 and 40.9 mg/l day, respectively. Particle size of CSM was found to affect the EPA production, and a finely ground CSM (100 mesh) was determined to be best for EPA production. The variation in the fatty acid content of total fatty acid (TFA) indicates that EPA was synthesized through the n‐6 route in P. irregulare and Δ12 desaturase was the key enzyme for EPA biosynthesis. Sodium carbonate was determined to be notably good at removing free gossypol attached to biomass. After fungal biomass from each flask had been harvested from Na2CO3‐supplemented medium, 1 % (w/v) Na2CO3 solution was used to wash the mycelia three times; free gossypol (FG) was not detected (detection limit 0.0018 %). This work provides a new approach using cottonseed meal to produce EPA through fungal fermentation. 相似文献