钨合金圆筒爆破试验破片分布的统计分析

采用圆筒爆破试验方法研究了易碎型钨合金的破片分布特征,并与93W合金的结果进行了对比.对破片的数量和质量分布特征进行了统计分析,发现易碎型钨合金的破片率明显高于93W合金,而且破片的均匀性也明显好于93W合金,但易碎钨合金的破片回收率低于93W合金,而且受装药量的影响较大.     

基于MSA法的高心墙堆石坝地震沉降易损性分析

多条带分析法(MSA)是新近提出的一种针对离散强度因子的易损性分析方法,为结构安全评估提供了有效路径,但目前在土石坝工程领域应用较少。本文针对高心墙堆石坝,选取坝顶震陷率为性能指标,建议了轻度、中度和重度破坏三个等级;考虑地震动的随机性,采用MSA法开展了易损性研究,得到了不同破坏等级的易损性曲线和概率,为大坝的强震性能评价提供准则和参考;不同条带数量下地震易损性分析结果表明,适当减少水平条带数量,对易损性结果影响不大,这有利于计算工况的减少。     

Na_2O-TeO_2系统玻璃形成液体脆性的研究

通过测量Na2 O -TeO2 系统玻璃转化区的热容曲线 ,对该系统不同成分玻璃形成液体的热力学和动力学脆性进行研究。结果表明 :该系统玻璃形成液体从热力学和动力学综合看脆性程度介于强弱之间 ,为中性偏脆性。随着氧化钠含量的升高 ,玻璃形成液体的脆性增强。用Kissinger方程和Ritland -Bartanev方程 ,得到的在玻璃转变区的结构松弛激活能十分接近。对该系统玻璃形成液体脆性参数的计算也得到该玻璃形成液体脆性分类的相同结果     

Optimal non-fragile controller realization algorithm and application to control problems

To reduce the fragility encountered in controller implementation, which is a measure of extent to describe small perturbations in controller parameters caused by rounding-off errors or component tolerances, and keep the system stability and performance, approaches of weighted eigenvalue sensitivity and stability radii comparison were used for computation and reduction of controller fragility. An algorithm has been derived for the efficient reduction of controller fragility, which used eigenstructure decomposition to obtain the suboptimal solution. The algorithm was tested for different control problems through reducing their fragility by a large margin. Different canonical forms were analyzed for fragility, including controllable canonical form, observable canonical form, modal canonical form, balanced realization and optimal (non-fragile) form. Different realizations were implemented through C language Matlab EXecutable (CMEX) S-function discrete state space block. Double precision calculations were performed. Open and closed loop controller realizations were compared with simulink state space (optimal) block. Results of comparison indicate that the optimal non-fragile controller realization shows better results both in open loop and closed loop realization.     

储罐地震易损性数值仿真分析

为了研究储罐的抗震性能,忽略储罐罐壁的质量,将储罐中的液体质量简化为三质点体系模型,地基土由两个弹簧和两个阻尼器模拟.考虑罐体的平动和转动,建立了在水平地震激励下储罐的动力方程;给出了随机变量的概率模型和基于易损性理论的失效概率计算方法.通过对大庆某油库2×104 m3和5×104m3两种大型储罐进行数值仿真方法的地震易损性分析.结果表明:随着地震烈度的增大,储罐的易损性逐渐增大;5×104 m3储罐的抗震性能要好于2×104 m3储罐;2×104 m3和5×104 m3储罐的主要失效模式分别是抗失稳和抗提离.由此可见从多个失效模式对储罐进行地震易损性研究比从单一失效模式进行易损性研究更加科学.     

基于复杂网络理论的典型电力电子电路复杂性研究

基于复杂网络对电力电子电路的复杂性进行了研究,指出了复杂网络在电力电子技术中运用的结合点并以三相桥式全控整流电路及三相电压型桥式逆变电路为研究对象,提出用复杂网络的特征参数来分析该电路拓扑特性的方法,并对其鲁棒性及脆弱性进行了分析研究.最后对电力电子电路复杂性研究结果存在的问题进行了分析和总结.     

Preparation of Adrenochrome Hydrogel Patch, Gel, Ointment, and the Comparison of Their Blood Coagulating and Wound Healing Capability

The aim of this study is to make an effective blood coagulant and wound healing agent, which on its topical application on ruptured skin would help in instant coagulation of blood and ongoing healing of wound. The hydrogel has been prepared by mixing 28% w/v gelatin and 21% w/v PVA in distilled water, and heated to 40°C followed by addition of a blood coagulant at a lower temperature. Beeswax, alcohol, liquid paraffin, and adrenochrome were mixed, triturated, and heated accordingly to prepare adrenochrome ointment. Polyvinyl alcohol and glycerin were mixed and heated and the drug was added at a lower temperature, and stored at 4-5°C to form adrenochrome gel. Gelatin alone has cell adhesion property. Adrenochrome is a blood coagulant. Therefore, gelatin with adrenochrome in hydrogel has a synergistic effect in wound healing. To evaluate the efficacy of these three different formulations, incisions were made on the backs of three mice and simultaneously adrenochrome containing hydrogel patch, gel, and ointment were applied on the wound and observed at regular intervals for half an hour to examine the rate of blood coagulation and kept under observation for 2 days to study the rate of wound healing. The efficacy of all these three formulations was compared to appraise the most effective blood coagulating and wound healing agent.     

条件均值谱选取记录的结构抗倒塌易损性分析

以抗倒塌易损性分析方法中的强震记录选取环节为研究对象,为了更好体现不同场址的地震动危险性差异,利用目标地区地震概率危险性分析的设定地震解耦结果构建条件均值谱（CMS）,进而将其进行多次调幅得到对应的目标谱,将匹配选波结果作为增量动力分析方法（IDA）的输入.以自振周期为0.5、1.0和1.5 s的3个平面框架为算例,在中国两个城市的地震安全性评价工作的基础上构建CMS谱,进行IDA分析,并将与当地一致概率谱、罕遇地震规范谱以及ATC63数据集得到的结果进行对比讨论,结果表明基于规范目标谱得到的抗倒塌易损性概率曲线最陡峭,基于一致概率谱与ATC63数据集得到的抗倒塌易损性概率曲线次之,CMS对应的抗倒塌易损性概率曲线最平缓.同时,对于较长周期的1.5 s结构,本文建议采用包络CMS谱来考虑多阶振型的影响,否则采用单点周期CMS谱会使得倒塌易损性计算结果显著低估实际的倒塌超越概率.     

基于复杂网络理论的宝鸡公交网络构建与分析

选取陕西省宝鸡市的43条公交线路和344个公交站点,以公交站点作为节点,相邻站点之间存在公交线路作为连边,基于复杂网络理论构建了宝鸡公交网络模型。对网络的统计性质与拓扑特征分析表明,公交网络是稀疏的,具有无标度特性以及部分小世界性质,网络度分布服从幂律分布,少数枢纽节点在网络中起重要的作用,对应于城市的关键站点或主要换乘站点。公交网络同时存在鲁棒性与脆弱性,网络稳定性的研究可为城市公交网络的优化及交通规划提供一定的理论依据。     

基于地震易损性解析函数的概率地震风险理论研究

基于不确定性传递,推导了考虑本质不确定性的地震易损性函数和考虑知识不确定性的地震易损性函数的解析表达式,并给出了其参数确定方法。证明了基于位移的函数与基于地震动强度的函数之间存在一致性。推导了考虑知识不确定性的地震易损性点估计函数的置信度水平。利用地震风险等于地震危险性与地震易损性的卷积,采用幂指数形式的地震危险性函数,进一步将已获得的地震易损性解析函数拓展得到概率地震风险函数的解析形式。利用得到的地震易损性与风险的解析函数,可简化地震易损性和风险评估的过程,方便对不同结构体系进行概率地震安全评估。