An approach to measure infill matric suction of irregular infilled rock joints under constant normal stiffness shearing

Rock joints infilled with sediments can strongly influence the strength of rock mass. As infilled joints often exist under unsaturated condition, this study investigated the influence of matric suction of infill on the overall joint shear strength. A novel technique that allows direct measurement of matric suction of infill using high capacity tensiometers (HCTs) during direct shear of infilled joints under constant normal stiffness (CNS) is described. The CNS apparatus was modified to accommodate the HCT and the procedure is explained in detail. Joint specimens were simulated by gypsum plaster using three-dimensional (3D) printed surface moulds, and filled with kaolin and sand mixture prepared at different water contents. Shear behaviours of both planar infilled joints and rough joints having joint roughness coefficients (JRCs) of 8–10 and 18–20 with the ratios of infill thickness to asperity height (t/a) equal to 0.5 were investigated. Matric suction shows predominantly unimodal behaviour during shearing of both planar and rough joints, which is closely associated with the variation of unloading rate and volumetric changes of the infill material. As expected, two-peak behaviour was observed for the rough joints and both peaks increased with the increase of infill matric suction. The results suggest that the contribution of matric suction of infill on the joint peak normalised shear stress is relatively independent of the joint roughness.     

Bearing Failure Optimization of Composite Double-Lap Bolted Joints Based on a Three-Step Strategy Marked By Feasible Region Reduction and Model Decoupling

To minimize the mass and increase the bearing failure load of composite doublelap bolted joints, a three-step optimization strategy including feasible region reduction, optimization model decoupling and optimization was presented. In feasible region reduction, the dimensions of the feasible design region were reduced by selecting dominant design variables from numerous multilevel parameters by sensitivity analyses, and the feasible regions of variables were reduced by influence mechanism analyses. In model decoupling, the optimization model with a large number of variables was divided into various sub-models with fewer variables by variance analysis. In the third step, the optimization sub-models were solved one by one using a genetic algorithm, and the modified characteristic curve method was adopted as the failure prediction method. Based on the proposed optimization method, optimization of a double-lap single-bolt joint was performed using the ANSYS^® code. The results show that the bearing failure load increased by 13.5% and that the mass decreased by 8.7% compared with those of the initial design of the joint, which validated the effectiveness of the three-step optimization strategy.     

智能卡与信息高速公路的数据库

介绍一种用智能卡访问信息高速公路中匿名和可认证数据库的机制。     

由ZF—6玻璃片构成的磁光旋转器

所提出的磁光旋转器是由Ｖｅｒｄｅｔ常数小的普通ＺＦ－６小玻璃片和带有窄缝隙的小电磁铁组成，当电磁铁线圈的功耗为１０Ｗ时，可得到２１°的法拉第旋转。     

唐钢薄板坯连铸连轧生产中半无头轧制技术分析

介绍了热轧薄带钢生产中半无头轧制的优点，并对唐钢薄板坯连铸连轧生产中半无头轧制的工艺方案和关键技术进行了技术分析。     

CAE在家用电器开发设计中的应用

本文论述了CAE技术及其在家用电器开发中应用流程,并介绍了CAE技术在家用电器开发中的应用及开发实例。最后提出了CAE在实际分析应用中应注意的问题。     

一种新的轨迹聚类及有效性评价方法

为解决轨迹聚类问题,提出一种新的无监督轨迹聚类及聚类有效性评估方法。通过建立双层字符串轨迹模型,计算得到轨迹间距离并用作聚类依据。提出轨迹同距点比例的概念,以此作为聚类工具,并采用类内平均同距点比例作为聚类有效性评价值。利用麻省理工大学(Massachusetts Institute of Technology,MIT)停车场行人路径数据集进行实验,实验结果表明,新的无监督聚类算法能较好地完成轨迹聚类任务,平均类内同距点比例能够很好地衡量分类效果。     

A Polynomial Algorithm for Computing Elementary Siphons in a Class of Petri Nets

A set of elementary siphons plays a key role in the development of deadlock prevention policies for automated manufacturing systems. This paper addresses the computation problem for elementary siphons in a subclass of Petri nets which are basic systems of simple sequential processes with resources (BS³PR) and can model many automated manufacturing systems. An algorithm for enumerating elementary siphons is established by the one‐to‐one relationship between maximal perfect resource‐transition circuits (MPCs) and strict minimal siphons. A set of MPCs is first computed, followed by a set of elementary siphons in a BS³PR. The presented algorithm is proved to have polynomial‐time complexity. An example is used to illustrate the algorithm.