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排序方式: 共有10000条查询结果,搜索用时 343 毫秒
991.
An engine exhaust manifold made of cast iron cracks during thermal shock testing. The test process is simulated by finite element analysis. The manifold is formulated as a linear heat transfer and thermoelasticity problem in a variational form. Analytical expressions for shape design sensitivities of general three-dimensional problems are presented, using the material derivative approach. A hybrid approach is described and used during the optimization process. This approach takes advantage of the direct and the adjoint variable methods and is the most efficient in calculating the sensitivity of the structural responses. After the finite element model is verified by comparing the results with those from testing, the engine exhaust manifold is optimized with respect to its geometry. 相似文献
992.
奇异摄动系统的极限解 总被引:3,自引:0,他引:3
本文在前人工作的基础上,利用广义函数理论讨论了一般形式下的奇异摄动系统E(ε)(?)=A(ε)x+B(ε)u在v→0~+时的极限解问题,得出了这一极限解存在的充要条件。 相似文献
993.
994.
995.
JD Ragland DM Censits RC Gur DC Glahn F Gallacher RE Gur 《Canadian Metallurgical Quarterly》1996,60(2-3):135-145
The Paired Associate Recognition Test (PART) was developed to measure declarative memory using Wisconsin Card Sorting Test (WCST) stimuli, so that both tasks could be administered during functional neuroimaging to differentiate memory and executive function, and associated frontal and temporal lobe activation in schizophrenia. The current study was designed to compare PART and WCST performance in schizophrenic patients and to examine effects of medication and symptomatology. The PART, WCST, and standard declarative memory tasks were administered to 30 chronic schizophrenic patients and 30 matched healthy control subjects. Supporting task validity was the finding that patients were equally impaired on the PART and the WCST. Neuroleptics did not appear to affect performance. The effect of anticholinergic medication correlated negatively with WCST performance in a small subsample. Severity of schizophrenia-specific symptoms measured at intake on the Brief Psychiatric Rating Scale correlated negatively with performance on the WCST. These results support the application of the PART and WCST in future functional neuroimaging studies. 相似文献
996.
997.
介绍了两种制备多孔硅的方法:电火花刻蚀法和激光辐射腐蚀法。讨论了这两种新方法制备的多孔硅样品的结构和发光特性,同时,与电化学法制备的多孔硅的结构和发光特性进行了比较。最后指出这两种新方法对于多孔硅形成机理和发光机制研究是有所帮助的。 相似文献
998.
GF Wagner RC Fargher C Milliken BA McKeown DH Copp 《Canadian Metallurgical Quarterly》1993,93(2):185-191
The aims of this study were to determine the most appropriate duration for the measurement of the maximal accumulated O2 deficit (MAOD), which is analogous to the anaerobic capacity, to ascertain the effects of mass, fat free mass (FFM), leg volume (Vleg) and lower body volume (V1b) on anaerobic test performance, to examine the reproducibility for peak power output (Wpeak) or maximal anaerobic power using an air-braked cycle ergometer and to produce approximations for the percentages of aerobic and anaerobic metabolism during exercise of short duration but high intensity. A group of 12 endurance trained cyclists [mean age 25.1 (SD 4.6) years; mean body mass 73.43 (SD 7.12) kg; mean maximal oxygen consumption 5.12 (SD 0.35) l.min-1; mean body fat 12.5 (SD 4.1) %] accordingly performed four counterbalanced treatments of 45, 60, 75 and 90 s of maximal cycling on an air-braked ergometer. The mean O2 deficit of 3.52 l for the 45-s treatment was significantly less (P < 0.01) than those for the 60 (3.75 l), 75 (3.80 l) and 90-s (3.75 l) treatments. These data therefore indicate that in predominantly aerobically trained subjects the O2 deficit attains a plateau after 60 s of maximal cycling on an air-braked ergometer. Statistically significant interclass correlation coefficients (P < 0.05) between the anthropometric variables (mass, FFM, Vleg and Vlb) and Wpeak or maximal anaerobic power (0.624-0.748) and MAOD (ml) or anaerobic capacity (0.666-0.772) furthermore would suggest the relevance of taking into account muscle mass during anaerobic tests.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
999.
北京谱仪(BESⅡ)顶点探测器数据获取系统是北京谱仪数据获取系统的一部分,该子系统电子学采用快总线标准,本文描述了该系统的硬件结构和软件系统,软件包括快总线系统的微码软件和上层控制软件,该系统的死时间为1.5ns,对BESⅡ系统总死时间的贡献小于0.5ms。 相似文献
1000.