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31.
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《Catalysis communications》2008,9(3):431-436
Ion-exchanged Pd–ZSM-23 (1 wt% Pd) with Na form and H form was well characterized and examined in the hydrodehalogenation of bromobenzene. TPR and XPS results suggested that Pd species dispersed in the different location of ZSM-23. Catalytic test was successfully carried out in mild conditions, using hydrazine hydrate as the hydrogen donor, and no by-products were detected. Recycling test of Pd–NaZSM-23 showed that the catalytic performance did not decrease remarkably until four recycle runs. 相似文献
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《International Communications in Heat and Mass Transfer》2005,32(1-2):214-223
The present paper analyses the entropy generation of the fully developed laminar convection in a helical coil with constant wall heat flux and presents the optimal design based on the minimum entropy generation principal. The important design parameters, including Reynolds number (Re), coil-to-tube radius ratio (δ) and nondimensional coil pitch (λ) are varied to investigate their influences on the entropy generation. The results presented in this paper cover Re range of 100–10,000, δ and λ range from 0.01 to 0.3. Compared with Re and δ, the coil pitch λ is found to have minor influence on the entropy generation. For a demonstrated case, the minimum entropy generation occurs in the range bounded by Re from 2271 to 4277 and δ from 0.17 to 0.3, within which the irreversibility of the system is lowest and the system performance would be optimum. The details show that there is an optimal Re for a helical coil with a fixed δ; meanwhile for a helical coil flow with a specified Re, the smaller δ should be selected when the Re is larger than 5000, and the larger δ should be selected when the Re is less than 5000. These results provide worthwhile information for heat exchanger designers to find the optimal helical coil design from the viewpoint of the thermodynamic second law. 相似文献
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《Journal of the European Ceramic Society》2005,25(9):1629-1636
Ultimate tensile strength of five different continuous fiber-reinforced ceramic matrix composites (CMCs), including SiCf/BSAS (two dimensional (2D), 2 types), SiCf/MAS (2D), SiCf/SiC (2D), and Cf/SiC (2D, 2 types), was determined as a function of test rate at 1100–1200 °C in air. All five CMCs exhibited a significant dependency of ultimate tensile strength on test rate such that the ultimate tensile strength decreased with decreasing test rate. The dependency of ultimate tensile strength on test rate, the applicability of preload technique, and the predictability of life from one loading configuration (constant stress-rate loading) to another (constant stress loading) all suggested that the overall, phenomenological delayed failure of the CMCs would be governed by a power-law type of slow crack growth. 相似文献
38.
《Journal of Systems Architecture》2007,53(7):417-436
Modern network applications require high performance and consume a lot of energy. Their inherent dynamic nature makes the dynamic memory subsystem a critical contributing factor to the overall energy consumption and to the execution time performance. This paper presents a novel, systematic methodology for generating performance-energy trade-offs by implementing optimal Dynamic Data Types, finely tuned and refined for network applications. Our systematic methodology is supported by a new, fully automated tool. We assess the effectiveness of the proposed approach in four representative, real-life case studies and provide significant energy savings and performance improvements compared to the original implementations. 相似文献
39.
LIUZhi-qiang MAWei ZHOUGuo-qing NIUFu-jun WANGJian-zhou CHANGLi-wu ZHOUJin-sheng 《中国矿业大学学报(英文版)》2005,15(1):21-25
The main factors that influence the temperature field of frozen subgrade were analyzed.The experimental equipment for simulating frozen subgrade was built up,and the declining regulating tubes were placed at the foot of the embankment. By means of this equipment two simulating experiments of controlling temperature filed of frozen subgrade were carried out in the laboratory. One method is to collect natural cold energy, and the other one is to collect natural cold energy ccompanied by artificial refrigeration simultaneously. The result indicates that the latter is an effective method for maintaining the stability of the frozen subgrade. 相似文献
40.
潮水盆地北部亚盆地中侏罗统层序地层及沉积演化特征 总被引:4,自引:0,他引:4
在系统分析研究区地表露头、岩心、测井和地震资料的基础上,运用层序地层学理论和方法,针对陆相盆地层序地层分析的实际,将湖水盆地北部亚盆地中讲罗统龙凤山组划分为4个三级层序和2个二级层序.通过系统的沉积体系及沉积淀化分析,发现从一个三级层序到另一个三级层序,或物源区有很大变化,或沉积作用方式发生变化;物源区随时间的变化,反映了构造的控制作用. 相似文献