Economic design of inspection strategies to monitor dispersion in short production runs

Short-run productions are common in industrial environments where flexibility is required in the manufacturing of parts and several product variants can be produced. Monitoring process stability during the production run is strategic to avoid the occurrence of an excessive number of non conforming units which can lead to excessive scrap or rework costs. The selection of the best control strategy can be obtained with respect to an economic objective by minimizing the cost associated with the implementation strategy. In this paper, several strategies including preventive maintenance, Shewhart, EWMA and CUSUM control charts are compared to monitor process dispersion. Constraints related to the line productivity and the inspection activities configuration have been included in the problem formulation. A proper optimization algorithm has been developed to cope with the investigated problem. A large benchmark of process scenarios has been investigated and the obtained results show that the selection of the best strategy is not a straightforward task due to the influence of several process operating parameters. Finally, a numerical example is detailed to get more insight about the investigated problem.     

Predicting the thermal conductivity of composite materials with imperfect interfaces

This paper compares the predicted values of the thermal conductivity of a composite made using the equivalent inclusion method (EIM) and the finite element method (FEM) using representative volume elements. The effects of inclusion anisotropy, inclusion orientation distribution, thermal interface conductance, h, and inclusion dimensions have been considered. Both methods predict similar overall behaviour, whereby at high h values, the effective thermal conductivity of the composite is limited by the inclusion anisotropy, while at lower h values, the effect of anisotropy is greatly diminished due to the more dominant effect of limited heat flow across the inclusion/matrix interface. The simulation results are then used to understand why in those cases where it has been possible to produce CNF reinforced Cu matrix composites with a large volume fraction of well dispersed CNFs, the measured thermal properties of the composite have failed to meet the expectations in terms of thermal conductivity, with measured conductivities in the range 200–300 W/m K. The simulation results show that, although degradation of the thermal properties of the CNFs and a poor interfacial thermal conductance are very likely the reasons behind the low conductivities reported, great care should be taken when measuring the thermal conductivity of this new class of materials, to avoid misleading results due to anisotropic effects.     

低碳钢在碳化氨水介质中短裂纹疲劳扩展规律的探讨

根据短裂纹的观点，讨论了低碳钢在碳化氨水介质中短裂纹疲劳扩展的规律。得出在短裂纹疲劳扩展范围内，随Δｋ增加，断裂从ＣＦ→ＳＣＦ→Ｆ转变；Δｋ（１ＳＣＣ）≈２１０Ｎ／ｍｍ（３／２）；在腐蚀疲劳条件下外加阴极保护电位促进短裂纹扩展；充氢条件下，大大加速短裂纹疲劳扩展。     

向列型液晶中短程关联对H－J－L理论的修正

向列型液晶中短程关联有重要的物理效应．但分于两体势包含高阶项时，给出可靠计算遇到困难．本文在格胞理论的基础上引入新的数值方法，从而给出短程关联对Ｈ－Ｊ－Ｌ理论的修正．     

连续深梁和短梁支座反力的分析及计算

本文根据有限元方法计算的结果,分析比较了连续深粱、短梁和浅粱支座反力的特点,给出了均布荷载和集中荷载作用下的连续深梁和短粱支座反力曲计算公式,可供工程实践应用并可供编制《钢筋砼深梁设计规程》参考。     

短信接口及其应用程序的开发

短信接口程序是解决移动技术在企业网络中应用问题的有效途径,它能够把方便快捷的短信技术与企业各应用系统无缝对接.文章通过介绍广州石化厂信息中心编制的短信接口程序及其在生产管理中的应用情况,以期达到尽快推广短信接口技术,有效提高生产管理成效.     

基于振动信号小波包提取和短时能量分析的高压断路器合闸同期性的研究

该文提出了一种分析高压断路器合闸同期性的新方法将小波包提取算法和短时能量分析方法相结合，利用小波包分解与重构原理将断路器合闸振动信号分解到不同频段中，并对代表高频冲击信号的分解系数进行重构，然后运用短时能量分析方法对重构后的信号进行分析，辨识出合闸变位点。通过对三相合闸过程的分析，得出三相同期性。通过MATLAB仿真分析和实验结果验证了该方法的有效性。     

短切炭纤维增强沥青基C/C复合材料的力学性能

利用模压半炭化成型工艺在大气环境下制备出了短切炭纤维增强沥青基C／C复合材料（简称SCFRC）。研究了短切炭纤维的体积分数对SCFRC材料的体积密度和力学性能的影响规律。借助光学显微镜和扫描电镜对其微观组织和断口形貌进行了观察，分析了短切炭纤维对SCFRC材料的增强机制。结果表明，当短切炭纤维的体积分数由0％增大到11．8％时，SCFRC材料的力学性能随之呈线性增加；短切炭纤维增强SCFRC材料的机制主要有裂纹偏转效应、桥联效应以及脱粘和拔出效应。     

Comparative study of analytical and numerical algorithms for designing reinforced concrete sections under biaxial bending

This paper presents a comparative study of different integration methods of stresses (both analytical and numerical) for concrete sections subjected to axial loads and biaxial bending. Such methods are applied to circular and rectangular sections. The constitutive equation used is a parabola-rectangle from the Eurocode-2. The comparison was performed with regard to the accuracy and the computational speed of each method. The objective of the paper is to determine which of the integration methods compared is more efficient in computing the interaction surfaces for rectangular and circular sections. The analytical method proposed by Barros et al. [Barros MHFM, Barros A, Ferreira C. Closed form solution of optimal design of rectangular reinforced concrete sections. Eng Comput 2004;21(7):761–76] for rectangular sections is compared with the numerical method termed “modified thick layer integration” proposed by Bonet et al. [Bonet JL, Romero ML, Miguel PF, Fernandez MA. A fast stress integration algorithm for reinforced concrete sections with axial loads and biaxial bending. Comput Struct 2004;82(2–3):213–25] and with the well-known fiber method. Furthermore, two new methods are proposed for circular sections: one analytical and one numerical based on the Gauss–Legendre quadrature. The results of both methods are compared with the classical layer decomposition method.     

计算线路断相加短路故障的新方法

本文在常规的故障分析方法中引入补偿原理、迭加原理和互易定理，提出了一 种无需修改原网各序节点阻抗(或导纳)阵，快速计算互感或无互感线路断相 加短路故障的新方法。经实例计算表明，文中算法正确、有效。