挤密桩地基非饱和黄土变形强度特性的三轴试验研究

用非饱和土三轴仪和GDS应力路径三轴仪对兰州张家台变电站工地挤密桩复合地基桩间非饱和黄土和原状黄土进行系统的试验研究,通过同时控制吸力和净室压力的三轴排水剪切试验,分析探讨了挤密桩间黄土和原状饱和黄土的应力-应变性状及强度规律,得到了各自的变形和强度参数,并将这些参数进行了比较和分析,利用规范推荐的方法量化了灰土挤密桩对桩间非饱和黄土在地基承载力方面的改善作用。     

具有正交(g,f)-因子分解的子图

设G是一个图 ,g (x)和f (x)是定义在V (G)上的整数值函数 ,且对任意的x∈V (G) ,设g (x)≤f (x) ,H是G的一个子图 ,F ={F1,F2 ,… ,Ft}是G的一个因子分解 ,如果对任意的 1≤i≤t,|E (H)∩E (Fi) |=1 ,则称F与H正交。闫桂英和潘教峰在文 [3]中提出如下猜想 :设G是一个 (mg+k,mf-k) -图 ,1≤k相似文献   

环状两相流空泡份额新析

对圆管内环状两相流的空泡份额进行了分析.首先推导出气相摩擦乘子的一般表达式,然后求得空泡份额与滑速比的解析式,并进行了分析讨论.与有关文献结果的比较表明:在一定的压力范围内文中所得的解是正确、可信的.     

二层粘弹阻尼复合结构的优化设计

构造二节点八自由度有限元模型对二层粘弹弱约束阻尼复合结构的动力学特性进行了数值分析,其计算结果与实验结果基本一致.利用此有限元模型研究了各层阻尼材料的几何及物理参数对复合结构阻尼性能的影响.     

关于内燃机原理若干问题的分析

本文分析了柴油机的最大扭矩、扭矩储备系数、喷油系统喷油量与柱塞几何供油量的差异和变化规律,认为这3个参数的现行定义不尽合理,并给出了新的定义。     

三相整流系统的故障分析

利用相量图分析了三相整流系统所有故障情况下交直流侧电压波形,进一步得到了整流系统各种故障对直流侧电压纹波因数和交流侧线电压畸变率的影响。最后得出了一些重要的结论。     

建筑构件的火灾危险性评估

火灾中,起火建筑的内部构件以及相邻建筑物的外部构件都要受到火灾高温及火焰热的作用。本文定量评估了威胁上述建筑构件的火灾因素．旨在为人们综合考虑采取合理的防火技术措施提供理论依据。     

奇异积分方程在裂纹板条动态断裂分析中的应用(I)

利用积分变换方法,将含Ｇｒｉｆｉｔｈ裂纹的无限长板条问题转化为Ｌａｐｌａｃｅ变换域中一Ｃａｕｃｈｙ型奇异积分方程。通过求解奇异积分方程和对裂纹尖端场的渐近分析,获得了Ｌａｐｌａｃｅ变换域中的动态应力强度因子。     

Adaptive fault-tolerant control based on boundary estimation for space robot under joint actuator faults and uncertain parameters

Since the joint actuator of the space robot executes the control instructions frequently in the harsh space environment, it is prone to the partial loss of control effectiveness (PLCE) fault. An adaptive fault-tolerant control algorithm is designed for a space robot system with the uncertain parameters and the PLCE actuator faults. The mathematical model of the system is established based on the Lagrange method, and the PLCE actuator fault is described as an effectiveness factor. The lower bound of the effectiveness factors and the upper bound of the uncertain parameters are estimated by an adaptive strategy, and the estimated value is fed back to the control algorithm. Compared with the traditional fault-tolerant algorithms, the proposed algorithm does not need to predetermine the lower bound of the effectiveness factor, hence it is more in line with the actual engineering application. It is proved that the algorithm can guarantee the stability of the closed-loop system based on the Lyapunov function method. The numerical simulation results show that the proposed algorithm can not only compensate for the uncertain parameters, but also can tolerate the PLCE actuator faults effectively, which verifies the effectiveness and superiority of the control scheme.     

A hybrid method for simulation factor screening

Factor screening is performed to eliminate unimportant factors so that the remaining important factors can be more thoroughly studied in later experiments. Controlled sequential bifurcation (CSB) and controlled sequential factorial design (CSFD) are two new screening methods for discrete‐event simulations. Both methods use hypothesis testing procedures to control the Type I Error and power of the screening results. The scenarios for which each method is most efficient are complementary. This study proposes a two‐stage hybrid approach that combines CSFD and an improved CSB called CSB‐X. In Phase 1, a prescreening procedure will estimate each effect and determine whether CSB‐X or CSFD will be used for further screening. In Phase 2, CSB‐X and CSFD are performed separately based on the assignment of Phase 1. The new method usually has the same error control as CSB‐X and CSFD. The efficiency, on the other hand, is usually much better than either component method. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2010