空间薄壁梁完全拉格朗日格式几何刚度矩阵

根据Timoshenko梁理论和Vlasov薄壁杆件理论,通过设置单元内部节点,对弯曲转角和翘曲角采取独立插值的方法,建立了可以考虑剪切变形、弯扭耦合和二次剪应力影响的空间薄壁截面梁几何非线性有限元模型。以拉格朗日格式描述几何非线性应变推得几何刚度矩阵.算例表明所建立模型具有良好的精度,适用于空间薄壁结构的几何非线性有限元分析.     

Sperm viability in the reproductive tract of females in a population of Sceloporus mucronatus exhibiting asynchronous reproduction

Asynchronous reproduction is a common phenomenon in high-elevation populations of lizards from Central México. Sperm storage in the reproductive tract of females is the mechanism for making oocyte fertilization possible. Our study addresses questions related to functional oviductal sperm storage of females mating on different dates throughout the reproductive season. A population of Sceloporus mucronatus with copulation in the summer and ovulation in the fall was chosen for this experiment. Eleven females that copulated in the field during June and 13 females that copulated in captivity during August were maintained in the laboratory until parturition. The number of pregnant females and the litter sizes produced in each experimental group were indicative of the viability of the stored sperm. Sperm stored in the reproductive tract of females were able to fertilize eggs after 4 months. No significant differences were found in the number of pregnant females between the 2 experimental groups nor in the litter sizes that they produced. We found that the amount of time sperm were held in the female reproductive tract (ca. 3 months) had no effect on the capacity of sperm to fertilize eggs. Histological examination of 8 oviducts collected before the mating season eliminated the possibility of sperm storage from one year to the next. In this system, sperm retention could have evolved as a response mechanism to deal with the asynchrony between sexes in the reproductive cycles. However, we cannot rule out alternative hypotheses.     

ETFE双层气枕计算分析及比较

基于U.L.格式的非线性有限单元法,编制了ETFE双层气枕找形分析、受荷分析的计算程序,并选取圆形、正六边形、正三角形、菱形及正方形5种工程中常用的气枕作为计算模型进行对比分析.在找形分析时,将矢高、内压和初始张力作为控制参数进行计算并依次给出了三者之间的相互关系.在受荷分析时,考虑6种给定的荷载工况,计算了ETFE气枕体积、内压的变动以及膜面的主应力.数值计算结果表明,形状与圆形相差较大的双层气枕其力学性能变化明显.在气枕的体积和内压变化不大时,可直接根据气枕上层膜面的主应力判定气枕的工作状态.     

Simulating FAS-induced apoptosis by using P systems

In contrast to differential equations, P systems are an unconventional model of computation which takes into consideration the discrete character of the quantity of components and the inherent randomness that exists in biological phenomena. The key feature of P systems is their compartmentalised structure which represents the heterogeneity of the structural organisation of the cells, and where one can take into account the role played by membranes in the functioning of the system, for example signalling at the cell surface, selective uptake of substances from the media, diffusion across different compartments, etc. We show here that P systems can be a reliable tool for Systems Biology and could even outperform in some cases the current simulation techniques based on differential equations. We will also use a strategy based on the well known Gillespie algorithm but running on more than one compartment called Multi-compartmental Gillespie Algorithm.     

Genetic background of phenotypic variation

A noteworthy feature of the living world is its bewildering variability. A key issue in several biological disciplines is the achievement of an understanding of the hereditary basis of this variability. Two opposing, but not necessarily irreconcilable conceptions attempt to explain the underlying mechanism. The gene function paradigm postulates that phenotypic variance is generated by the polymorphism in the coding sequences of genes. However, comparisons of a great number of homologous gene and protein sequences have revealed that they predominantly remained functionally conserved even across distantly related phylogenic taxa. Alternatively, the gene regulation paradigm assumes that differences in the cis-regulatory region of genes do account for phenotype variation within species. An extension of this latter concept is that phenotypic variability is generated by the polymorphism in the overall gene expression profiles of gene networks. In other words, the activity of a particular gene is a system property determined both by the cis-regulatory sequences of the given genes and by the other genes of a gene network, whose expressions vary among individuals, too. Novel proponents of gene function paradigm claim that functional genetic variance within the coding sequences of regulatory genes is critical for the generation of morphological polymorphism. Note, however, that these developmental genes play direct regulatory roles in the control of gene expression.     

自由形态单层壳体栓接节点承载力性能研究

针对自由形态（free-form）单层壳体中的栓接节点,运用ABAQUS通用有限元软件对多种工况作用下的节点承载力性能进行了计算机模拟.分析了螺栓预紧力和杆件轴向拉压应力等因素对节点刚度和承载能力的影响.理论分析和试验研究表明,栓接节点处连接截面在荷载作用下会产生明显的相对转动变形,整体结构分析时对这类连接不能按全刚接连接考虑.最后,在总结受力性能和破坏模式的基础上,给出了栓接节点的使用维护和工程设计建议.本文研究将为自由形态壳体结构中的栓接节点设计提供理论依据.     

┱?例杨金彪;福建省南平市第

鸨?114尼美舒利致肝功能损伤1例陈瑶;李岚;厦门市妇幼保健院药剂科,上海儿童医学中心药剂科 厦门361000,上海200000尼美舒利;;肝功能损害0海峡药学Strait Pharmaceutical Journal118-119R725.9E06938E;E069_38陈瑶;114-115门诊药房实行专科药师制度的必要性陈成辉;何丽芳;     

Self-Dual Hadamard Bent Sequences

A new notion of bent sequence related to Hadamard matrices was introduced recently,motivated by a security application(Solé, et al., 2021). The authors study the self-dual class in length at most 196. The authors use three competing methods of generation: Exhaustion, Linear Algebra and Gr?bner bases. Regular Hadamard matrices and Bush-type Hadamard matrices provide many examples. The authors conjecture that if v is an even perfect square, a self-dual bent sequence of length v always exists. The ...     

西瓜怎样科学施肥和有效防治病害?

西瓜如何施肥、防治病害,对于西瓜的优质高产是个关键。本刊这期刊登张其林同志的两篇文章,介绍著名平湖西瓜科学施肥和有效防治病害的经验,供广大瓜农参考。     

RSS拓补结构机座的动态优化

以燃气轮机透平端RSS(旋转对称支承板)机座为研究背景,通过用D’Alembert原理建立了RSS机座的拓补优化域和等价边界条件,从而实现了用均匀化方法的RSS机座拓扑结构优化,得到了旋转对称的弧形支承板拓扑结构的机座.然后,结合原来RSS机座的机构特征在ANSYS workbench中建立了RSS拓补结构光滑有限元模型,并进行了工作条件下的模态分析,以前三阶模态振型中轴承座的振型作为当量静载荷加载到原模型对比计算,验证边界条件的正确性.以RSS机座弧形支承板的四个关键尺寸为设计变量,以机座的变形量和应力为目标函数,进行了随频率变化的动态优化设计.通过优化改变了RSS拓补结构的动态特性,使固有频率远离了工作频率.