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1.
推导了钢筋砼结构可靠性优化设计所需的约束条件和目标函数,并建议通过求主要破坏机构来计算结构系统的可靠度,在采用分部优化策略的基础上,实现了结构系统可靠性分析与结构优化设计的有机结合,并将该方法和确定变量的现行设计方法进行了比较,指出了钢筋砼框架结构的系统可靠性优化设计的优点,为工程设计和修订规范提供了理论依据。  相似文献   
2.
Fluid and melt inclusions in mantle xenoliths are thought as direct samples to study mantle liquids. Here we apply Raman mi- crospectroscopy and microthermometry to fluid/melt inclusions in lherzolite xenoliths in Qiaoshan basalts, a Miocene volcano in Linqu, Shandong Province, eastern China. These inclusions include (1) early CO2 fluid inclusions, (2) early carbonate melt inclu-sions, (3) late CO2 fluid inclusions, and (4) late silicate melt inclusions. Among the early CO2 fluid inclusions, most consist of...  相似文献   
3.
首次将巨轮型纳米多孔多金属氧酸盐Na15[MoVI126MoV28O462H14(H2O)700.5[MoVI124MoV28O457H14(H2O)680.5·ca.400H2O通过层层自组装的方法,与聚乙烯基亚胺(PEI)通过静电作用自组装形成纳米超薄多层膜。该膜的制备过程通过紫外可见光谱进行监测,巨轮型纳米多孔多金属氧酸盐的特征吸收峰的吸收值随着层数的增加呈线性增长关系,表明在纳米超薄多层膜的组装过程中巨轮型多金属氧酸盐的结构没有被破坏,自组装成膜的过程是一个层层均一、反复生长的过程,每层吸附循环沉积的聚电解质和多金属氧酸盐的量相等。对纳米超薄多层膜的偏振紫外光谱的研究表明巨轮型纳米多孔多金属氧酸盐分子在纳米超薄膜中不是杂乱无章随意排列堆积的,而是在带高负电荷的巨轮型纳米多孔多金属氧酸阴离子间存在的静电排斥作用下彼此平行倾斜在基片表面并且与基片表面成一定的取向角从而减低整个体系的能量达到最稳定状态。  相似文献   
4.
几种新型二烃基锡羧酸酯类化合物的合成与表征   总被引:1,自引:1,他引:0  
以二氟碳基锡氧化物(n-C6F13CH2CH2)2SnO,二正丁基锡氧化物(n-C4H9)2SnO和不同结构的芳香羧酸ArCOOH为原料,较高产率(68%~95%)地合成了尚未见文献报道的7种二烃基锡羧酸酯类化合物,并对这些化合物进行了表征.这些化合物属于两种构型{[R2Sn(OOCAr)]2O}2(A)和R2Sn(OOCAr)2(B),在这两类化合物(A)和(B)中,中心锡原子具有不同的配位形式和配位数.  相似文献   
5.
研究了试题信息数据库的系统结构及试卷智能生成方法。提出采用启发式搜索策略中的A*算法来改善智能组卷的智能化指标;给出一种逻辑组合检索方法来实现大容量试题信息的快速查询与检索;同时还介绍了系统的应用及其性能分析。  相似文献   
6.
针对《金工》课教学的实际情况,论述了课程体系改革的必要性和重要性,并且提出课程教改体系建设的思路和规划.  相似文献   
7.
P chromosomes may carry a genetic system that inhibits the Ph gene in wheat. Abnormal chromosome synapsis in wheat-Agropyron cristatum addition line II-21-2 (additional 1·4 recombinant P chromosome) was observed in this study. The results of cytogenetics and Ph1 gene amplification showed that the Ph1 gene was normal and the average number of quadrivalents or hexavalents was determined to be 0.41 and 0.13, respectively, in pollen-mother cells of wheat-Agropyron cristatum addition line II-21-2. The analysis o...  相似文献   
8.
Lost circulation controlling & killing material has been a focused issue since a long time ago. A novel leak resistance fluid with the raw materials such as SDS, SDBS, HES, PAM and proprietary productions has been developed from laboratory. The experiment and application shows that the new leak resistance fluid can plug leaking passage of different sizes simultaneously. Observing with 1000 to 2000 time microscope, it is found that the working liquid contains a kind of spherical material which has the microstructure of “one core, two layers, and three membranes”. When it is in a static state, the inside of the material looks like an airbag and the outside looks like some fuzzy things which has high gel strength. While when it is in a dynamic state, the fuzzy thing is cut or scattered and flow ability becomes much better. That is the reason why it is called fuzzy-ball. When the diameter or the width of the leak passage is greater than the fuzzy-ball’s, the fuzzy-ball accumulates in conical shape to decompose the working fluid pressure of liquid column to achieve blocking; when the diameter or the width of the leak passage is equivalent to the fuzzy-ball’s, the fuzzy-ball changes from sphere to oval–shape to increase the resistance to the leak passage and plug the holes; when the diameter or the width of the leak passage is smaller than the fuzzy-ball’s, the leaks could be blocked up by the non-permeable membrane formed by the gel of high strength in the working fluid. In these cases, the leak passages of different sizes could be blocked comprehensively.  相似文献   
9.
高性能沥青路面是美国公路战略研究计划的重要研究成果之一。在我国,1995年江苏交通科学院率先引进高性能沥青路面技术,自2000年第一条实验路以来,超过1000万吨高性能沥青路面设计的混合料铺筑在1000多公里的高速公路上。目前,全国有40余套高性能沥青路面的胶结料试验设备,80余台高性能沥青路面旋转压实机为进一步应用高性能沥青路面技术奠定了物质基础。  相似文献   
10.
The characteristics of low-frequency waves in magnetic reconnection are studied using two-dimensional hybrid simulation code. In a coordinate system moving with fluid,the time series of a magnetic field perpendicular to the magnetic reconnection plane,By, is transformed into the power spectrum via fast Fourier transformation,while the wave propagation direction and polarization are determined by minimum variance analysis of the electric field.The results show that low-frequency Alfvén ion-cyclotron waves dominate the reconnection area.These waves have frequencies 0-1Ωp(where Ωp is the local proton gyro frequency)and all are left-handed circularly polarized.Among these waves,large-amplitude turbulence,with frequencies of 0-0.6Ωp and isotropic propagation,dominates the outflow regions.This can cause the reversal of By in the quadrupole structure.In the inflow regions, dominant waves,propagating mainly parallel to the ambient magnetic field,have higher frequencies and smaller amplitudes.The frequency of the main peak of wave energy is usually higher than 0.5Ωp.  相似文献   
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