基于静力测量参数的结构损伤状况评估理论

在对结构进行检测测试后,通过对测试数据的分析,判断结构单元特性,可以识别出结构损伤的位置和程度。本文依据结构的刚度变化和位移测试数据,介绍了一种基于静力实验结果的损伤状况评价方法,为进一步补强加固提供了理论依据。     

非线性损伤谱特征研究

提出了基于Park和Ang损伤模型的弹塑性反应谱(损伤反应谱,简称"RD谱")的研究方法.考虑结构极限状态设计,并通过自编DBRS程序,研究得到了RD谱族;RD谱综合考虑了结构最大弹塑性位移和结构累积滞回耗能的耦合影响,更加合理地反映结构在罕遇地震作用下的弹塑性行为.研究发现RD谱与已有Rμ谱具有类似的特征.通过大量时程分析和拟合得到其回归公式及其相关系数.此外,提倡的RD谱和Rμ谱的定性比较分析,所得结果相对于其它研究结果中是最小的,主要由于两个方面的原因:一是RD谱考虑结构极限状态的情况,二是考虑地震动持时的作用,表明结构抗震设计或评估应当考虑地震动的持时因素.     

大庆长垣南部地区浅层气成因类型及富集规律研究

对大庆长垣南部地区黑帝庙油层天然气地球化学分析的基础上,结合有机质的热演化规律和前人的天然气分类标准,认为黑帝庙油层天然气为生物气和油型气两种成因类型。综合松辽盆地构造演化特征、断层活动规律、砂体分布规律和圈闭类型分析,认为黑帝庙油层天然气的富集主要受源断裂和圈闭类型控制。由源断裂控制的断背斜圈闭是天然气富集的有利场所。     

The bacterial LexA transcriptional repressor

Bacteria respond to DNA damage by mounting a coordinated cellular response, governed by the RecA and LexA proteins. In Escherichia coli, RecA stimulates cleavage of the LexA repressor, inducing more than 40 genes that comprise the SOS global regulatory network. The SOS response is widespread among bacteria and exhibits considerable variation in its composition and regulation. In some well-characterised pathogens, induction of the SOS response modulates the evolution and dissemination of drug resistance, as well as synthesis, secretion and dissemination of the virulence. In this review, we discuss the structure of LexA protein, particularly with respect to distinct conformations that enable repression of SOS genes via specific DNA binding or repressor cleavage during the response to DNA damage. These may provide new starting points in the battle against the emergence of bacterial pathogens and the spread of drug resistance among them.     

结构损伤诊断的遗传算法研究

引入遗传算法处理试验得到的动力信息对结构的损伤进行了诊断 .针对要处理的问题 ,提出了多父体变量级杂交和变量微调等新的改进策略 ,并运用于固端梁、连续梁和框架等多个结构的损伤诊断 ,取得了满足工程要求的结果.     

Sea urchin embryo as a model for analysis of the signaling pathways linking DNA damage checkpoint,DNA repair and apoptosis

DNA integrity checkpoint control was studied in the sea urchin early embryo. Treatment of the embryos with genotoxic agents such as methyl methanesulfonate (MMS) or bleomycin induced the activation of a cell cycle checkpoint as evidenced by the occurrence of a delay or an arrest in the division of the embryos and an inhibition of CDK1/cyclin B activating dephosphorylation. The genotoxic treatment was shown to induce DNA damage that depended on the genotoxic concentration and was correlated with the observed cell cycle delay. At low genotoxic concentrations, embryos were able to repair the DNA damage and recover from checkpoint arrest, whereas at high doses they underwent morphological and biochemical changes characteristic of apoptosis. Finally, extracts prepared from embryos were found to be capable of supporting DNA repair in vitro upon incubation with oligonucleotides mimicking damage. Taken together, our results demonstrate that sea urchin early embryos contain fully functional and activatable DNA damage checkpoints. Sea urchin embryos are discussed as a promising model to study the signaling pathways of cell cycle checkpoint, DNA repair and apoptosis, which upon deregulation play a significant role in the origin of cancer. Received 10 April 2007; accepted 23 April 2007     

基于非局部模型的混凝土损伤的数值模拟

分析了局部损伤模型在进行混凝土应变软化模拟时存在的问题:网络依赖性和零能量损耗问题;在传统的非局部损伤模型中引入光滑的权函数,构造一种新的非局部损伤模型。计算表明该非局部损伤模型可较好避免有限元在应变软化模拟时的网络依赖性,预测出的荷载-位移反应与实际情况吻合较好。     

精冲过程的韧性断裂

金属塑性加工时，材料内部会出现应变集中和空穴长大两种损伤，导致材料的承载能力下降与丧失．分析了精密冲裁时均匀塑性流动形成光洁表面以及空穴长大引起的断面撕裂现象，从材料细观损伤角度阐明了精冲原理，比较了精冲与普通冲裁两种不同的材料分离机制，并对精冲过程的数值模拟结果进行了讨论．     

内压圆筒应力场对损伤萌生的影响

压力容器各部位因受力不同而具有不同的损伤萌生倾向。文中依据连续介质损伤力学的观点，提出以 Ｙ０＝ Ｕ· Ｒｃ 及ｇｒａｄ Ｙ０ 作为评价结构损伤萌生倾向的参数，其中 Ｕ是等效弹性比能， Ｒｃ 是与应力三轴度有关的函数。着重指出：不连续应力和热应力显著地提高内压圆筒的损伤萌生倾向。     

工型钢构件在水平循环荷载作用下的局部损伤行为

本文就工型钢构件在模拟地震作用的水平循环荷载作用下，危险断面的损伤累积及发展行为进行了描述，给出了损伤变量表达式。并对文献［１］中部分实验构件的损伤进行了追踪计算，得到了满意的结果。为在结构抗震的二阶段设计中的定量控制及结构损伤的进一步研究提供可贵的资料