共查询到10条相似文献，搜索用时 205 毫秒
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Ye Zhiming 《上海大学学报(英文版)》1999,(1)
１ Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｔｈｅｓｏｌｕｔｉｏｎｓｏｆｔｅｍｐｅｒａｔｕｒｅａｎｄｄｉｓｐｌａｃｅｍｅｎｔｆｉｅｌｄｓｏｆｄａｍｓａｒｅｏｆｉｎｔｅｒｅｓｔｔｏｍａｎｙｒｅｓｅａｒｃｈｅｒｓｉｎｈｙｄｒｏｐｏｗｅｒｉｎｄｕｓｔｒｙａｎｄｏｔｈｅｒｓｆｏｒｙｅａｒｓ,ｂｅｃａｕｓｅｏｆｔｈｅｉｒｉｍｐｏｒｔａｎｃｅｉｎｔｈｅｓａｆｅｔｙｏｆｄａｍｓ．Ｇｅｎｅｒａｌｌｙｓｐｅａｋｉｎｇ,ｎｕｍｅｒｉｃａｌｓｏｌｕｔｉｏｎｓｗｅｒｅｄｅｖｅｌｏｐｅｄｔｏｕｎｄｅｒｓｔａｎｄｔｈｅｄｉｓｐｌａｃｅ… 相似文献
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INTRODUCTION Vertical cylindrical steel tanks widely used for fluid storage generally consist of a thin bottom plate, a cylindrical shell, and a fixed or floating roof. Large tanks constructed on soft foundations are susceptible to various types of settlement deflections. The set-tlement components are: uniform settlement, planar tilt and differential settlement. The uniform settle-ment and planar tilt cause rigid-body deflection or rotation of the tank, and so, are of relatively little i… 相似文献
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文双春 《衡阳师范学院学报》1997,(3)
利用Maxwell方程组的积分形式证明了电磁场切线方向边值关系的独立性：当介质分界面两侧的电场和磁场满足切线方向的边界条件时，也同时自动满足法线方向的边界条件，反之则不成立。 相似文献
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A good efficiency performance of a pump over a wide range of displacement conditions is crucially important for variable pump control systems to save energy. However, according to the literature, less attention has been paid to the understanding of the efficiency, leakage flow, and compression flow characteristics of the pump with respect to displacement conditions. In this study, a test bench was built, and a novel explicit volumetric loss model was proposed to investigate these problems. The overall efficiency is found to drop considerably with the decreasing displacement. The volumetric losses range from 13% to 47% of the total power losses of pump at the rated speed, under the conditions of pressure ranging from 5 to 35 MPa and displacement ranging from 13% to 100% of full displacement. The highest proportion of compression flow losses in the total volumetric losses of pump at the rated speed can reach up to 41% when the pressure and displacement are greater than 30 MPa and 88% of full displacement, respectively; after that, the proportion gradually decreases with decreasing displacement. However, the leakage flow generally increases with decreasing displacement, or may decrease first and begin to increase after the minimum with the further decrease of displacement. In the components of leakage of slipper/swash plate pair, the squeeze leakage is found to reach a magnitude equal to that of the Poiseuille leakage. The findings can guide the further research and design of pumps with better efficiency performance. 相似文献
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我国名牌大学学科领域离世界一流有多远——从世界大学学科领域排名说起 总被引：5，自引：0，他引：5
CHENG Ying LIU Nian-cai 《高等教育研究》2007,28(10):1-8
通过对我国名牌大学各大学科领域的世界排名和学术指标进行分析,发现大陆部分名牌大学的理科和工科的科研产出规模虽然较大,但其中高质量论文的比例较低,同时缺乏国际级学术大师和重大原创成果;生命学科和医药学科相比世界上的高水平大学还处在起步阶段;社会科学研究的国际化程度较低。为此,我们建议理性看待我国名牌大学及其学科领域现阶段所处的国际地位;坚定建成世界一流大学和学科领域的信念,继续加大对若干所名牌大学的重点投入;明确内涵式发展的理念,尽快实现由数量积累到质量提高的转变。 相似文献
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The influence of the change of structure plane size on seismic response was studied for a soil-structure interaction system. Based on the finite element method, a soil-structure interaction calculation model was established to analyze the seismic response by changing the structure plane size and choosing different earthquake waves for different soil fields. The results show that when the natural periods of vibration for different structure plane sizes are close, under the same earthquake wave, the total displacement on the top layer of the structure and the foundation rotation displacement decrease with the increase of structure plane size, and the proportion of superstructure elastic selfdeformation displacement to the total displacement increases with the increase of structure plane size. While for different types of sites and seismic waves, under the horizontal and vertical seismic waves, the seismic responses of different plane sizes have a similar change rule. 相似文献
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Alice Sullivan Samantha Parsons Francis Green Richard D. Wiggins George Ploubidis 《British Educational Research Journal》2018,44(4):663-680
This article assesses the chances of entering the top 5% of earners for a British cohort currently in their 40s. We assess the difference made by a university degree from an elite (Russell Group) or non‐elite university, and from different undergraduate fields of study. Our study uses rich longitudinal data from the 1970 British Cohort Study (BCS70). This allows us to control for an unusually large range of potential confounding factors, including childhood socio‐economic circumstances, cognitive scores, secondary schooling and prior qualifications. We find that large raw differences in the chances of achieving a top salary are strongly attenuated by our controls, but substantial differences between degree subject areas remain. The large gap between men and women in the chance of gaining a top salary is not explained by the type of degree achieved, and we found no evidence of gender differences in the gains from institutional prestige or particular fields of study. 相似文献
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殷秀叶 《洛阳师范学院学报》2014,(11):52-54
提出了一种基于同级属性的重复记录检测方法.首先给出了同级属性的判断方式,然后通过查找数据集中的同级属性,来缩减数据集中需要计算的属性个数,提升相似重复记录检测的效率.实验结果表明,受同级属性在数据集中所占比例的影响,该方法能够不同程度的提高相似重复记录检测的效率. 相似文献
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高压P-LDMOS的失效实验分析表明其沟道区的高峰值电场会导致沟道区的热载流子效应,从而将降低高压P-LDMOS的可靠性.借助半导体器件专业软件Tsuprem-4和Medici的模拟给出了高压P-LDMOS沟道区的电场分布情况,模拟结果显示在沟道区存在2个峰值电场,讨论了产生这2个峰值电场的原因,同时给出了降低这2种峰值电场的有效方法———适当增加沟道的长度和降低沟道区的浓度.实验结果表明采用这2种方法优化得到的高压P-LDMOS的栅击穿电压得到了很大的提高,同时P-LDMOS的可靠性也得以大幅提高. 相似文献