Consolidation of Soft Clay Foundations Reinforced by Stone Columns under Time-Dependent Loadings

This paper presents an analytical solution for the consolidation of soft soil foundations reinforced by stone columns under time-dependent loadings. The differential equations of the foundations reinforced by stone columns are obtained including smear and well resistance under arbitrary applied loadings. The closed-form solutions of pore pressure and the overall average degree of consolidations are obtained for some common types of loadings, such as step loading, ramp loading, and cyclic trapezoidal loading. By solving the equations using a semianalytical method, the comparisons agree very well with the existing analytical solutions, which verify the correctness and accuracy of the proposed methods. Using the solutions obtained, some selected charts are presented and the relevant consolidation behavior is investigated and discussed.     

Axial Compression of Footings in Cohesionless Soils. II: Bearing Capacity

An extensive database of full-scale field load tests was used to examine the bearing capacity for footings in cohesionless soils. Each load test curve was evaluated consistently to determine the interpreted failure load (i.e., bearing capacity) using the L1-L2 method. This test value then was compared with the theoretical bearing capacity, computed primarily using the basic Vesi? model. The comparisons show that, for footing widths B>1?m, the field results agree very well with the Vesi? predictions. However, for B<1?m, the results indicated a relationship between B and the predicted-to-measured bearing capacity ratio. Accordingly, a simple modification was made to the bearing capacity equation, and the resulting predictions are very good.     

示波器探头种类及其工作原理

介绍了示波器探头的种类及其工作原理,主要从探头的负载效应、探头的补偿、探头的接地引线电感等方面论述了示波器探头在测量过程中对被测信号的影响和注意的一些问题.     

Three-dimensional analysis of load transfer micro-mechanisms in fibre/matrix composites

This study gives a detailed analysis of load distributions around fibre breaks in a composite. In contrast to other studies reported in the literature, the analysis considers different configurations of composite damage from the failure of a few to the failure of many fibres. The model considers three types of matrix behaviours (elastic, elastic–plastic and viscoelastic) with or without debonding at the broken fibre/matrix interface. In this way, the usual limitations of the finite element approach are overcome so as to take into account the number and interactions of broken fibres whilst maintaining an evaluation of the various fields (stresses in particular).     

多目标满载装卸货问题的蚁群算法研究

满载装卸货问题是广泛存在于物流运输领域的重要组合优化难题。为了有效求解实际情况下多目标的满载协同运输问题,设计了双层最大最小蚁群算法。利用蚁群算法的正反馈和并行性,通过不同层次蚁群之间的信息素传递,实现对问题的两个优化目标同时优化。通过实验表明了该算法可行而有效。     

一种结构化P2P网络动态负载均衡算法的研究

负载均衡是P2P网络的研究热点之一,当前负载均衡技术存在负载均衡程度低、假设条件过多等问题.提出一了种增强型负载均衡算法ELB_P2P,它根据节点的承栽能力为其分配相应大小的可动态调整的ID地址空间以及合理的载荷,在负载转移时自动选择延迟小带宽高的轻栽节点,并引入负载转移流量控制机制.实验表明,相对于Chord等传统P2P协议,ELB_P2P算法有更快的负载均衡速度、更小的负载均衡开销,系统稳定性好,在网络重栽情况下也能取得较低的负载不平衡度,并且对节点属性没有苛刻的限制和假定.     

DHT负载均衡的必要性

在分布式哈希表(DHT)中,节点ID通常随机选择,但这并不意味着DHT是负载均衡的.仿真结果表明,Chord网络中的负载是不均衡的.在总结对该问题相关工作的基础上,理论上证明了DHT算法本质上的不均衡性,并精确给出节点负载不均衡性的上界范围,仿真验证了分析结论.     

泵阀复合驱动执行器速度/位置控制方法

针对液压升船机、多自由度试验平台、长行程单出杆液压缸控制系统高性能和高效能的要求,结合阀控回路的高性能和泵控回路的高效能特点,采用阀控开式回路和泵控闭式回路并联驱动新回路.该回路兼顾效能和性能,但侧重于保持性能.为提高新回路运行过程中的平稳性及带负载的控制精度等性能,提出带有负载补偿量的速度/位置复合控制策略,确定负载...     

Analytical analysis and optimisation of the Rayleigh step slider bearing

In tribology, the Rayleigh step is known as a bearing with the highest load capacity amongst all other possible bearing geometries. In classical resources on tribology, it is also shown that there is an optimum geometry for the Rayleigh step providing the highest load capacity. However, the analyses are confined to a special case where the effect of hydrostatic pressure is neglected. Furthermore, the possible optimum parameters in terms of the friction force and/or friction coefficient as well as the lubricant flow rate have not been discussed. In this study, the Rayleigh step is comprehensively analysed including the effect of variations of pressure at the boundaries on the optimum parameters. In addition, the bearing is also optimised considering lubricant flow rate, friction force and friction coefficient. It is shown that the optimum bearing parameters are strictly dependent on the variations of the pressure at the boundaries. It is also verified that the optimum point(s) in terms of load capacity are not necessarily equal to the optimum point(s) considering friction coefficient and/or lubricant flow rate even though if there is no pressure difference between bearing endings.     

钢丝绳股内钢丝的载荷分布

应用微分几何理论分析钢丝绳结构特点及钢丝的空间螺旋缠绕关系,利用ANSYS软件开发常用的几种金属绳芯钢丝绳的建模程序,建立6×19IWS右同向捻和右交互捻两种钢丝绳的几何模型.通过适当的网格划分得到了钢丝绳的有限元模型,以钢丝绳一端约束三个方向自由度,另一端施加轴向集中载荷作为加载工况,确立模型求解的边界条件,并进行数值模拟.分析数值模拟结果,得出钢丝绳股内处于不同位置钢丝在长度方向上应力呈螺旋状分布,钢丝截面上应力呈中心对称分布的规律,对照分析两种捻向组合钢丝绳中对应钢丝的应力分布规律,指出捻向组合对钢丝绳股中钢丝应力分布的影响.确立钢丝绳拉伸试验方案,进行6×19IWS钢丝绳拉伸试验,用四种载荷下的拉伸变形量验证了数值模拟结果,试验结果与模拟结果基本吻合.