梁柱稳定性分析的突变理论方法

应用突变理论建立了两端铰支的梁柱失稳的尖点突变模型。借助数学方法，分析了粱柱失稳过程中平衡的特性。     

论世界历史的渐变与突变

世界历史的运动变化过程,既有渐变过程,也有突变过程。渐变是世界历史的缓慢的、稳定状态下的、连续性的变化;突变是世界历史的迅速的、失稳状态下的、不连续的变化。渐变与突变都可以包含有历史的量变和质变。在具体的历史过程中,渐变与突变又是相互依存、相互渗透、相互转化的,这就是世界历史演变方式的辩证统一过程。     

具有埋深效应的隧道围岩变形突变模型

针对突变理论分析具有埋深效应的隧道变形过程的不足,利用灰色理论对围岩变形的时间序列进行处理,建立改进的突变理论模型,并对隧道围岩变形进行分析,寻求围岩失稳判据的简便有效计算方法,为工程实践提供理论依据.     

细绳绷直瞬间的能量损失

对理想刚性细绳而言,当其一端受约束,在绳子绷直的瞬间,绳子方向弹力发生瞬间突变（弹力是由微小形变而产生,而微小形变所需时间极短,可忽略不计）．弹力突变导致瞬间由于弹力的冲量作用使沿绳子方向物体的分速度突变为0,只剩下垂直于绳子方向的分速度,于是瞬间导致能量损失（向内能转化）,解题时如对上述环节不清晰易造成错解,现举例说明．     

突变理论在医学上的应用

突变理论是以拓扑学、奇点理论为工具，对不连续现象做定性研究的新兴数学分支；介绍了突变理论的数学基础和突变种类。同时，应用突变理论，对中医学领域中“正”与“邪”的突变进行了探讨，并介绍了突变理论在西方医学中的应用。     

突变原因的实验分析

分析了S.E.Luria的波动实验、J.Lederberg的影印平板培养法在证明"突变是自发的"这一结论中的作用,简述了J.Cairns"定向突变"的观点。     

线粒体DNA突变与疾病

介绍了线粒体DNA的遗传学特性,试从分子水平上探讨mtDNA突变发生情况,阐明mtDNA的突变与线粒体病和衰老的关系,简要说明了人类mtDNA突变的类型和相应的线粒体病的特点.     

线粒体DNA突变与疾病

介绍了线粒体ＤＮＡ的遗传学特性,试从分子水平上探讨ｍｔＤＮＡ突变发生情况,阐明ｍｔＤＮＡ的突变与线粒体病和衰老的关系,简要说明了人类ｍｔＤＮＡ突变的类型和相应的线粒体病的特点。     

中学物理突变问题初探

本文时中学物理突变概念的建立,常见物理量的突变及如何进行突变教学作了一些初步探索;对通常认为的轻弹簧的弹力,物体的速度等物理量不能突变的观点作了分析。     

基于Mann-Kendall法的酒泉市近50年气候变化特征及突变分析

利用酒泉市所属6个站点1959-2008年的气温和降水资料,采用滑动平均、趋势分析和MannKendall等方法,分析该地区的气候变化的特征.结果表明:在全球变暖背景下,酒泉市的气温突变明显,而降水突变不明显.近50年来,酒泉市年平均气温和各个季节的平均气温呈显著变暖趋势,其中年平均气温在90年代中后期发生了突变,酒泉市东部的突变年份早于西部的突变年份;酒泉市年降水量呈微弱增长趋势,酒泉市东部的增长幅度略小于西部.这表明气候突变在酒泉市不同的地区会有不同的体现,突变时间不同步.     

关于梁柱节点不同强度等级混凝土的施工方法初探

梁柱节点的施工优劣直接影响着房屋的质量。高层建筑框架结构的梁柱节点比较复杂。梁柱不同强度等级混凝土分别浇捣进行施工时,要避免邻接面形成冷缝。只要采用针对性措施,并精心施工,梁柱节点高低强度等级混凝土交界处附近的裂缝完全可以得到避免。     

损伤粘弹性梁-柱的广义变分原理

从损伤的粘弹性材料的卷积型本构关系出发,建立了在小变形下损伤粘弹性梁-柱的控制方程,提出了以卷积形式表示的损伤粘弹性梁-柱弯曲问题的泛函,并给出了损伤粘弹性梁-柱的广义变分原理.应用这个广义变分原理,可分别给出梁-柱位移和损伤满足的基本方程,以及相应的初始条件和边界条件.     

钢筋混凝土框架结构加层改造设计探讨

本文结合武钢四烧电气室框架结构厂房的工程实例，根据原有框架结构房屋的检测鉴定结果，采用不同方案对其加层改造进行对比分析，选取了合理的加层方案，并通过计算分析确定了经济合理的加固方法，并对加层柱与下部框架梁柱钢筋的连接等关键技术措施进行了探讨。     

New Factor to Characterize Mechanism of “Strong Column-Weak Beam” of RC Frame Structures

Most reinforced concrete(RC)frame structures did not achieve the "strong column-weak beam" failure mode in recent big earthquakes, resulting in a large number of casualties and significant property loss. To deal with this serious problem, a new column-beam relative factor was proposed to characterize the relative yield situation of column ends and beam ends. By limiting the column-beam relative factor, RC frame structures could achieve the "strong column-weak beam" failure mode under the excitation of strong ground motions. The limit values of column-beam relative factor were calculated, analyzed and verified by using structural simulation models for corner columns in the bottom story of structures, which are destroyed most seriously in earthquakes. The results show that the limit values should be analyzed under bi-directional ground motion and with different axial compression ratios of columns. The peak ground acceleration(PGA)of ground motions has no significant effect on the limit values, while the type of strong ground motions has a significant effect on the limit values.     

Finite element analysis of dynamic stability of skeletal structures under periodic loading

INTRODUCTION Some structures fail geometrically before thestrength failure because of lack of stability and such afailure is known as instability failure or bucklingfailure. Determination of buckling load is importantin order to ensure the stability of a structure. If thestructure under consideration is subjected to a dy-namic load then this problem comes under the pur-view of dynamic stability problems. Examples areslender offshore structures subjected to periodic ex-citations and colum…     

Seismic behavior of diaphragm-through connections of concrete-filled square steel tubular columns and H-shaped steel beams

Based on the introductions of a type of diaphragm-through connection between concrete-filled square steel tubular columns (CFSSTCs) and H-shaped steel beams,a finite element model of the connection is developed and used to investigate the seismic behavior of the connection.The results of the finite element model are validated by a set of cyclic loading tests.The cyclic loading tests and the finite element analyses indicate that the failure mode of the suggested connections is plastic hinge at the beam with inelastic rotation angle exceeding 0.04 rad.The suggested connections have sufficient strength,plastic deformation and energy dissipation capacity to be used in composite moment frames as beam-to-column rigid connections.     

博弈策略、逆向选择与巨灾保险市场失灵的经济分析

文章通过对日本、西班牙等发达国家巨灾保险制度的分析,指出了我国巨灾风险保险体系建设的不足与差距。对我国巨灾保险市场现状的分析显示,我国巨灾保险市场存在着巨大的保险需求和有限的制度供给之间的矛盾,解决巨灾保险市场供求失衡的矛盾需要在政府的主导下、在法律体系完善的前提下、构建政府与商业性保险公司共同运作的巨灾保险体系,从而实现制度供给的增加。同时,完善金融制度改革,为巨灾保险基金、巨灾风险债券的设立和发行创造良好的外部环境。     

Numerical Simulation of Dynamic Response and Collapse for Steel Frame Structures Subjected to Blast Load

The progressive collapse of steel frame structures under the blast load was investigated using LS-DYNA. The multi-material Eulerian and Lagrangian coupling algorithm was adopted. A flu-id-structure coupling finite element model was established which consists of Lagrange element for simulating steel frame structures and concrete ground, multiple ALE element for simulating air and TNT explosive material. Numerical simulations of the blast pressure wave propagation, struc-tural dynamic responses and deformation, and progressive collapse of a five-story steel frame structure in the event of an explosion near above ground were performed. The numerical analysis showed that the Lagrangian and Eulerian coupling algorithm gave good simulations of the shock wave propagation in the mediums and blast load effects on the structure. The columns subjected to blast load may collapse by shear yielding rather than by flexural deformation. The columns and joints of steel beam to column in the front steel frame structure generated enormous plastic defor-mation subjected to intensive blast waves, and columns lost carrying capacity, subsequently lead-ing to the collapse of the whole structure. The approach coupling influence between struc-tural deformation and fluid load well simulated the progressive collapse process of structures, and provided an effective tool for analyzing the collapse mechanism of the steel frame structure under blast load.     

Numerical Simulation of Dynamic Response and Collapse for Steel Frame Structures Subjected to Blast Load

The progressive collapse of steel frame structures under the blast load was investigated using LS-DYNA.The multi-material Eulerian and Lagrangian coupling algorithm was adopted.A fluid-structure coupling finite element model was established which consists of Lagrange element for simulating steel frame structures and concrete ground,multiple ALE element for simulating air and TNT explosive material.Numerical simulations of the blast pressure wave propagation,structural dynamic responses and deformation,and progressive collapse of a five-story steel frame structure in the event of an explosion near above ground were performed.The numerical analysis showed that the Lagrangian and Eulerian coupling algorithm gave good simulations of the shock wave propagation in the mediums and blast load effects on the structure.The columns subjected to blast load may collapse by shear yielding rather than by flexural deformation.The columns and joints of steel beam to column in the front steel frame structure generated enormous plastic deformation subjected to intensive blast waves,and columns lost carrying capacity,subsequently leading to the collapse of the whole structure.The approach coupling influence between structural deformation and fluid load well simulated the progressive collapse process of structures,and provided an effective tool for analyzing the collapse mechanism of the steel frame structure under blast load.     

中国发展巨灾保险债券的构想

2004年是人类历史上的大灾年,十几个地处不同区域的国家分别遭受了台风、飓风、地震、海啸等自然灾害的袭击,造成重大人身伤亡和财产损失。在自然灾害频发的中国,传统的商业保险承保巨灾能力不足,再保险市场也无力为巨灾提供充分保障。因此,借鉴国际成功经验,进行金融创新,将巨灾风险向资本市场分散势在必行。文章在理论探讨的基础上,将中国具体金融机构可在巨灾债券运作模型中充当的角色进行初步定位,并对可能存在的问题进行逐一分析,从而对中国巨灾债券运作机制提出合理构想。