三维边坡稳定性的整体分析法及其工程应用

在水利水电工程中,有时需要考虑带有平行于滑动方向的侧向摩擦边界的滑动体的整体稳定性问题,现有的三维极限平衡法及其商用软件都没有考虑这种情况．因此其三维安全系数会被低估,而基于三维反演的滑面抗剪强度会被高估．本文将滑动体的侧向摩擦边界视为滑面的一部分,基于滑面法向应力表达式和分片插值技术,实现了能够考虑带有侧向摩擦边界的滑动体的三维严格极限平衡法．最后将所建议的方法用于正在建设中的大岗山水电站右岸坝顶高程以上边坡稳定性分析．     

复杂渠道工程三维渗流应力耦合分析与研究

渗流是导致渠道下沉、倾斜、断裂等诸多不良后果的重要因素,对渠道安全稳定运行危害较大．基于NURBS．TIN．BRep混合数据结构,构建南水北调中线工程某渠段的工程地质信息三维可视化模型,运用耦合VOF（volumeoffluid,流体体积函数）法的N—S（Navier．Stokes）方程,对研究区域进行渗流模拟,并采用流固耦合进行渠道稳定性计算,全面分析渠道在渗漏、下伏采空区等多种因素影响下的应力及位移状态．结果表明：渠道渗流对其稳定性影响较大,特别是对位移场的影响较为明显,渠道渗流将导致其自身产生相对较大的沉降,因此建议在实际施工过程中进行渠道的局部加固,并采取有效地渗流控制措施．     

具有圆弧形槽孔层合材料三维应力分析

基于一种修正的余能原理,建立了具有一个无外力圆柱面的新型三维层合杂交应力元,它可高效地分析具有圆柱形槽孔的厚、中厚、及薄层合材料的自由孔边三维应力分布. 根据建立的应力分量的应力函数表达式导出的单元应力场,严格满足层内以柱坐标表示的平衡方程、层间界面上应力连续条件、及圆柱面上无外力边界条件. 元间反力连续条件通过Lagrange乘子进行松弛. 层间位移保持连续,同时计入了横向剪切变形影响. 数值算例表明,该元不仅可以提供远较一般假定位移元及一般假定应力元准确的孔边应力分布,而且计算效率高、收敛快,同时,亦可用于多种圆弧形槽孔的应力分析.     

非饱和土的非正交弹塑性本构模型

从应变增量大小和方向的角度出发,以有效饱和度和Bishop有效应力作为基本本构变量,呈现了一个非饱和土的非正交弹塑性本构模型建模框架.建模框架采用非正交的塑性流动法则,直接通过屈服函数确定塑性应变增量的方向,避免了构造塑性势函数的困难.基于所提建模框架,利用屈服函数、硬化参数和土水特征曲线的具体表达式,发展得出一个非饱和土的非正交弹塑性本构模型.所提模型通过材料参数μ可以描述具有不同刚度的非饱和土的力学与水力行为.模型所需材料参数均具有明确的物理意义,且可以通过室内试验确定.利用两种经典应力路径(即恒基质吸力的常规三轴剪切路径和恒净应力的吸湿路径)分析了具有不同刚度的非饱和土的力学与水力行为.模型预测结果与非饱和土试验数据的对比验证了所提模型的优越性.     

基于灰色关联分析的医学图像三维插值方法

将灰色关联分析引入三维图像插值中,提出了一种新的插值方法:先通过灰色关联度来确定待插值点的最佳匹配点位置,再确定待插值点的灰度值.实验结果表明本文方法在基本不增大运算时间的情况下比传统的几种方法插值结果的均方差均有明显降低.     

三维双重孔隙-裂隙介质热-水-应力-迁移耦合模型及其有限元分析

建立了一种饱和-非饱和的双重孔隙-裂隙介质热-水-应力-迁移耦合三维模型,其特点是应力场和温度场是单一的,但具有不同的孔隙渗流场、裂隙渗流场和孔隙浓度场、裂隙浓度场,以及可考虑裂隙的组数、间距、方向、连通率和刚度对本构关系的影响,并研制出相应的三维有限元程序.通过与已有算例的对比,验证了该模型和程序的可靠性.针对一个假定的高放废物地质处置库,就岩体和缓冲层均为非饱和介质和放射性核素泄漏的情况进行了数值分析,考察了岩体中的温度、负孔隙水压力、地下水流速、核素浓度和正应力的状态.结果显示,缓冲层中的温度、负孔隙水压力及核素浓度呈现非线性的变化、分布;尽管裂隙水饱和度平均仅为孔隙水饱和度的1/9,但因裂隙的渗透系数比孔隙的渗透系数大4个数量级,故裂隙中地下水的流速约是孔隙中相应值的6倍;应力分布集中的区域位于缓冲层和处置孔壁交界两侧附近.     

降雨入渗过程中土质边坡的固-液-气三相耦合分析

边坡降雨入渗过程伴随着地下水湿润锋面的推进、孔隙气体的迁移和土体的变形,涉及土体固-液-气三相耦合作用.以往对边坡在降雨入渗条件下的非饱和渗流过程及其对边坡稳定性的影响研究大多基于单相流（Richard方程）模型或水-气两相流模型,而较少从固-液-气三相耦合角度分析孔隙气体迁移和土体变形对降雨入渗过程和稳定性变化过程的影响.本文基于连续介质力学原理和混合体理论,建立了边坡土体固-液-气三相耦合数学模型和有限元数值模拟方法.采用Liakopoulos砂柱排水实验成果验证了耦合模型和计算程序的正确性,深入分析了气体边界条件对排水过程的显著影响.在此基础上,采用固-液-气三相耦合模型,研究了土质边坡在降雨入渗过程中的地下水渗流、气体迁移以及变形和稳定性演化过程,揭示了孔隙气体迁移过程和土体变形过程对边坡湿润锋面的推进以及稳定性变化的阻滞和延缓作用.研究成果对于暴雨诱发滑坡机理与防治研究具有一定参考价值.     

Evidence for changes in cell shape from a 2-dimensional to a 3-dimensional substrate

Summary Chick embryo mesoderm cells were explanted to culture systems in vivo and in vitro and their subsequent movements were correlated with the external morphology as studied by SEM. In vitro cell movements are exaggerations of normal in vivo movements where a 2-dimensional substrate is encountered rather than a 3-dimensional environment.The authors are grateful to Mr J. Smith and Mrs S. Bulman who provided excellent technical assistance and to Mr G. L. C. McTurk who skillfully produced the scanning electron micrographs in the Leicester University Scanning Electron Microscope Unit.     

Evidence for changes in cell shape from a 2-dimensional to a 3-dimensional substrate.

Chick embryo mesoderm cells were explanted to culture systems in vivo and in vitro and their subsequent movements were correlated with the external morphology as studied by SEM. In vitro cell movements are exaggerations of normal in vivo movements where a 2-dimensional substrate is encountered rather than a 3-dimensional environment.     

一种土壤团聚体稳定性评估系统

团聚体稳定性是土壤结构的重要属性.国内外团聚体稳定性量化研究较少,而能够定量评估团聚体稳定性的系统也少.鉴于该研究现状,本文设计了一套土壤团聚体稳定性评估系统,它利用功率超声粉碎土水溶液中土壤团聚体,通过实时监测土水溶液温度和超声系统输入功率的变化,并根据能量转化与守恒定律计算出土壤超声分散能量,进而确定土壤团聚体的稳定性.在实验室环境下对澳大利亚新南威尔士州Namoi和Narrabri的两种不同质地土样进行测量,其土壤分散能量分别为328和207 J·g^-1,前者土壤结构更稳定.     

Redundant regulation of localization and protein stability of DmPar3

Apical–basal polarity is an important characteristic of epithelia and Drosophila neural stem cells. The conserved Par complex, which consists of the atypical protein kinase C and the scaffold proteins Baz and Par6, is a key player in the establishment of apical–basal cell polarity. Membrane recruitment of Baz has been reported to be accomplished by several mechanisms, which might function in redundancy, to ensure the correct localization of the complex. However, none of the described interactions was sufficient to displace the protein from the apical junctions. Here, we dissected the role of the oligomerization domain and the lipid-binding motif of Baz in vivo in the Drosophila embryo. We found that these domains function in redundancy to ensure the apical junctional localization of Baz: inactivation of only one domain is not sufficient to disrupt the function of Baz during apical–basal polarization of epithelial cells and neural stem cells. In contrast, mutation of both domains results in a strongly impaired protein stability and a phenotype characterized by embryonic lethality and an impaired apical–basal polarity in the embryonic epithelium and neural stem cells, resembling a baz-loss of function allele. Strikingly, the binding of Baz to the transmembrane proteins E-Cadherin, Echinoid, and Starry Night was not affected in this mutant protein. Our findings reveal a redundant function of the oligomerization and the lipid-binding domain, which is required for protein stability, correct subcellular localization, and apical–basal cell polarization.     

Stochastic stability of quasi-integrable Hamiltonian systems with time delay by using Lyapunov function method

The asymptotic Lyapunov stability of one quasi-integrable Hamiltonian system with time-delayed feedback control is studied by using Lyapunov functions and stochastic averaging method. First, a quasi-integrable Hamiltonian system with time-delayed feedback control subjected to Gaussian white noise excitation is approximated by a quasi-integrable Hamiltonian system without time delay. Then, stochastic averaging method for quasi-integrable Hamiltonian system is used to reduce the dimension of the original syst...     

Axillary 5 alpha-androst-16-en-3-one in men and women: relationships with olfactory acuity to odorous 16-androstenes

Axillary 5 alpha-androst-16-en-3-one (5 alpha-androstenone) levels were found to be significantly higher in men than in women but do not vary between left and right axillae, are not related to age, handedness or degree of hirsutism (in women) nor to anosmia to this steroid. In men (but not in women), levels are related linearly to axillary cholesterol concentrations but not to squalene. Olfactory thresholds for 5 alpha-androstenone varied widely, the lowest recorded being 0.2 ppb, but there was no difference in thresholds between men and women. Women (70%) found the smell 'repellant' but anosmia did not differ greatly between men and women (9-20%). Anosmia to the smell of 5 alpha-androst-16-en-3 alpha-ol was most marked in women (90%) rather than in men (45%). Axillary 5 alpha-androstenone values were generally consistent with the 'musky' or 'strong' smells of male axillary extracts, compared with the 'sweet' smell of those from female subjects.     

Purification and stability of specifically tritium labelled lysine vasopressin (Tyrosine2-3-T-lysine8-vasopressin)

Zusammenfassung Tyrosin²-3-T-Lysin⁸-Vasopressin, das vor 2 1/2 Jahren synthetisiert worden war, wurde auf CM-Sephadex-C-25-Säulen gereinigt. Die spezifische Radioaktivität des spezifisch markierten Hormons war nur auf 80% gefallen, was einen verhältnismässig kleinen Grad von Isotopaustausch für das Nonapeptid selber anzeigt.     

Demonstration of vascular dopamine receptors in membranes from rabbit renal artery using3H-spiroperidol binding

Summary Binding of³H-spiroperidol to membranes branes from rabbit renal artery was found to be saturable and of high affinity. Dopamine receptor antagonists inhibited binding much more potently thana-adrenergic antagonists and dopamine was much more potent than noradrenaline, indicating that³H-spiroperidol labels vascular dopamine receptors in rabbit renal artery.The skilful technical assistance of Mrs Doris Petermeyer and Miss Ulrike Jansen is gratefully acknowledged.