乌拉泊水库除险加固勘察及其成果分析

制定了乌拉泊水库除险加固勘察工作要点,并对库区进行了实际勘察。通过对勘察成果的详细分析,为乌拉泊水库的除险加固工程提供了重要依据,同时也为该水库的安全运行提供了科学的资料。     

质子交换膜燃料电池用催化剂及其稳定性改进方法研究进展

系统总结了质子交换膜燃料电池(PEMFC)用催化剂的种类,以及其在长时间运行过程中性能衰减的主要原因,归纳了近年来提高催化剂稳定性的改进方法,包括改变合金组成、对催化剂表面进行修饰、选择高稳定性催化剂载体、制备新型催化剂材料;最后提出了该催化剂材料研究中存在的问题和今后的发展方向。     

坝头单薄分水岭边坡支护方案探讨

大坝两岸单薄分水岭条形山体边坡支护对水库大坝安全运行起到重要意义,对此,阐述惠州抽水蓄能电站上水库单薄分水岭边坡支护采用钢筋砼框架锚杆加干砌石护坡面的处理措施.     

南水北调西线工程若干工程地质问题研究

 基于工程实践,探讨西线一期工程区域稳定性评价的原则和基本思路,根据有关资料,给出工程区的稳定性分区,认为西线工程位于基本稳定区,附近断裂大多数不具有活动性,坝址场区内没有发现活动断裂和地震震中分布,没有活动断裂穿越引水隧洞。隧洞围岩主要为II～III类围岩,局部为IV～V类围岩,岩爆强度不高,围岩大变形主要发生在板岩段和构造破碎带处,地质条件适合TBM施工。根据水文地质资料,给出各隧洞段的涌水量。可能引起强透水或涌水的地段主要在浅埋过沟段、向斜褶皱核部破碎岩体形成的富水段、断层破碎带及其影响带。     

基于Monte Carlo技术的临界滑面搜索算法的实现及改进

搜索临界滑面是边坡稳定分析的一项重要工作。本文对Venanzlo R Greco提出的Monte Carlo搜索算法进行了改进,增加一条几何合理性条件(除了滑面两端点,滑面与坡面不能相交),增加了方向控制与变自由度机制,这些措施有效地减少了不满足几何合理性条件的试算滑面,保证了搜索过程的准确、高效、稳定。笔者还将此算法加入到自主研发的边坡稳定分析软件ZSlope中,它还可以实时显示整个搜索过程。     

基于改进进化策略的CSCL任务分配自适应决策方法

本文针对在伸缩性很大的多用户多任务（MU-MT）网络协同学习环境中,如何获得稳定的总体效益最优化的任务分配问题,提出了一种基于改进进化策略的自适应决策方法。该方法在传统进化策略基础上,通过进化方向控制和自适应选择算子设计等改进,优化了收敛速度,并防止抖动和早熟。本算法的优点主要在于：运算规模能依据CSCL环境的变化自动调整,具有很强的环境自适应性,因而是在未知网络环境中提供稳健协同性能的有效解决方案。     

基于强度折减的拉格朗日差分方法分析土坡稳定性

运用连续介质显式拉格朗日有限差分方法,通过逐步折减土体的抗剪强度,来分析土坡稳定的安全系数。实例计算表明,强度折减系数达到某一数值时,土坡顶点的水平位移会快速增加。根据这一现象,提出了界定土坡破坏的坡顶位移增量标准。即坡顶位移增量与折减系数增量之比大于系数sc为土坡破坏,并建议了sc的取值。这样可避免强度采用折减方法分析土坡稳定时,以不收敛等"模糊"概念作为土坡破坏状态的判别标准,具有物理意义明确、客观具体、便于数值计算等特点。与瑞典圆弧法、简化Bishop法及Spencer法比较可见,这些方法的潜在滑动面形状相似、位置十分接近,说明本文方法及"破坏"状态的判别标准是合适的。文中对剪胀角的影响进行了讨论,得到"不考虑"剪胀性的关联流动法则会高估土坡稳定安全系数的结论。     

The Effect of Size and Shape of Austenite Grains on the Mechanical Properties of a Low‐Alloyed TRIP Steel

The effects of size and shape of austenite grains on the extraordinary hardening of steels with transformation induced plasticity (TRIP) have been studied. The deformation and transformation of austenite was followed by interrupted ex situ bending tests using electron backscatter diffraction (EBSD) in a scanning electron microscope (SEM). A finite element model (FEM) was used to relate the EBSD based results obtained in the bending experiments to the hardening behavior obtained from tensile experiments. The results are interpreted using a simple rule of mixture for stress partitioning and a short fiber reinforced composite model. It is found that both, the martensite transformation rate and the flow stress difference between austenite and martensite significantly influence the hardening rate. At the initial stage of deformation mainly larger grains deform, however, they do not reach the same strain level as the smaller grains because they transform into martensite at an early stage of deformation. A composite model was used to investigate the effect of grain shape on load partitioning. The results of the composite model show that higher stresses develop in more elongated grains. These grains tend to transform earlier as it is confirmed by the EBSD observations.     

Stability of fiber trajectories for winding toroidal pressure vessels

In this paper the fiber trajectory stability of filament wound toroidal pressure vessels is evaluated for two most frequently used patterns: single helical winding, helical and hoop winding. The basic equations of equilibrium for fibers on a torus are given based on netting analysis. The governing equations that determine helical winding angles along the meridional direction are derived for the two winding patterns. The slippage coefficients of the obtained fiber trajectories are calculated using the non-geodesic law and differential geometry. The condition between the hoop-to-helical thickness ratio and the relative bend radius of the toroid is also formulated to prevent fiber bridging on the concave surface. The fiber slippage and bridging tendencies are outlined and compared, corresponding to various relative bend radii and hoop-to-helical thickness ratios. The results show that the single helical winding process provides better stability of fiber trajectories, in terms of both fiber slippage and bridging, than the helical and hoop winding. The toroidal vessel with larger relative bend radius requires lower coefficient of friction between the fiber bundle and the supporting surface. The present analysis for fiber trajectory stability affords a useful reference tool for designing filament-wound toroidal pressure vessels.     

分数阶系统变阶次状态空间建模及稳定理论

结合分数阶微积分算子的叠加原理,提出了变阶次状态空间建模方法.将分数阶系统推广到状态空间领域,实现了最小阶状态空间转换,并可根据实际需要通过增加状态变量来提取某一阶次的输出信号.对于各阶次均小于1的变阶次状态空间实现的分数阶系统,提出了变阶次分数阶系统的稳定性判定定理.最后通过实例仿真验证了所提出方法的有效性.