数控小孔冲床网眼平板加工中的波浪纹缺陷成因分析及排除

文章就数控小孔冲床加工纺织烘干设备中帘子网眼平板产生波浪纹缺陷的原因,进行了全面、详细的理论分析.在排除机床、模具精度影响的基础上,针对压料机构运动误差产生的机理和不利影响,详细分析了网眼冲孔加工产生波浪纹缺陷的根本原因,提出了相应的改进措施,在实践中具有良好的实用效果.     

基于ILOG平台的求解动态车间作业调度问题优化算法研究

研究了基于约束规划和启发式搜索算法结合求解动态车间作业调度的问题。以最小化制造周期费用与总拖期惩罚费用之和为优化目标,通过建立调度模型、分析问题的优化特性,提出了基于约束规划的禁忌搜索启发式算法,根据与另外两种算法的比较结果,验证了此算法的有效性。     

A tabu search heuristic for a sequence-dependent and time-dependent scheduling problem on a single machine

This paper introduces a tabu search heuristic for a production scheduling problem with sequence-dependent and time-dependent setup times on a single machine. The problem consists in scheduling a set of dependent jobs, where the transition between two jobs comprises an unrestricted setup that can be performed at any time, and a restricted setup that must be performed outside of a given time interval which repeats daily in the same position. The setup time between two jobs is thus a function of the completion time of the first job. The tabu search heuristic relies on shift and swap moves, and a surrogate objective function is used to speed-up the neighborhood evaluation. Computational experiments show that the proposed heuristic consistently finds better solutions in less computation time than a recent branch-and-cut algorithm. Furthermore, on instances where the branch-and-cut algorithm cannot find the optimal solution, the heuristic always identifies a better solution.     

Deteriorating job scheduling to minimize the number of late jobs with setup times

Deteriorating jobs scheduling problems have been widely studied recently. However, research on scheduling problems with deteriorating jobs has rarely considered explicit setup times. With the current emphasis on customer service and meeting the promised delivery dates, we consider a single-machine scheduling problem to minimize the number of late jobs with deteriorating jobs and setup times in this paper. We derive some dominance properties, a lower bound, and an initial upper bound by using a heuristic algorithm to speed up the search process of the branch-and-bound algorithm. Computational experiments show that the algorithm can solve instances up to 1000 jobs in a reasonable amount of time.     

用InstallShield制作中文界面安装盘的高级技巧

本文介绍了用ＩｎｓｔａｌｌＳｈｉｅｌｄ制作安装盒的原理和方法,给出了其制作安装盘的一般步骤,并详细论述了用它制作安装盘的一些高级技巧。     

A heuristic algorithm for the just-in-time single machine scheduling problem with setups: a comparison with simulated annealing

This paper addresses the single machine early/tardy problem with unrestricted common due date and sequence-dependent setup times. Two algorithms are introduced to reach near-optimum solutions: the SAPT, a heuristic tailored for the problem, and a simulated annealing (SA) algorithm. It will be shown that SA provides solutions with slightly better quality; however, SAPT requires much less computational time. SAPT-SA is a hybrid heuristic that combines both approaches to obtain high quality solutions with low computational cost. Solutions provided by the three algorithms were compared to optimal solutions for problems with up to 25 jobs and to each other for larger problems.     

Solution approaches for the cutting stock problem with setup cost

In this paper, we study the Cutting Stock Problem with Setup Cost (CSP-S) which is a more general case of the well-known Cutting Stock Problem (CSP). In the classical CSP, one wants to minimize the number of stock items used while satisfying the demand for smaller-sized items. However, the number of patterns/setups to be performed on the cutting machine is ignored. In most cases, one has to find the trade-off between the material usage and the number of setups in order to come up with better production plans. In CSP-S, we have different cost factors for the material and the number of setups, and the objective is to minimize total production cost including both material and setup costs. We develop a mixed integer linear program and analyze a special case of the problem. Motivated by this special case, we propose two local search algorithms and a column generation based heuristic algorithm. We demonstrate the effectiveness of the proposed algorithms on the instances from the literature.     

Project scheduling under partially renewable resources and resource consumption during setup operations

There has been an increasing pressure on manufacturing industries to reduce energy consumption. In this study, we propose a new variant of RCPSP called RCPSP/πRC, which can deal with realistic energy constraints such as power restriction during peak hours, contract demand, and energy consumption during setup operations. First, we present an integer programming (IP) model and a constraint programming (CP) model of the RCPSP/πRC. Next, we present a heuristic mode restriction method called a mask calculation algorithm to achieve efficient searching by restricting selectable modes. Finally, through computational experiments, we evaluate the proposed methods and show their effectiveness.     

A branch and bound enhanced genetic algorithm for scheduling a flowline manufacturing cell with sequence dependent family setup times

This paper addresses the permutation flowline manufacturing cell with sequence dependent family setup times problem with the objective to minimize the makespan criterion. We develop a cooperative approach including a genetic algorithm and a branch and bound procedure. The latter is probabilistically integrated in the genetic algorithm in order to enhance the current solution. Moreover, the application of the branch and bound algorithm is based upon the decomposition of the problem into subproblems. The performance of the proposed method is tested by numerical experiments on a large number of representative problems.     

Mechanical behavior of ferritic grade 3Cr12 stainless steel—Part 1: Experimental investigations

Ferritic stainless steels are corrosion resistant steels with a low and stable cost. Widely used in automotive applications, structural applications using ferritic stainless steels are only emerging mainly because ferritics are partially covered by structural standards due to a shortage of design data. Computer models are more and more used to support the developments of conventional design methods based on expensive full-scale tests or trial and errors methods. And for the modeling of metal forming processes as well as structural behavior of members, it is necessary to afford an accurate knowledge of the mechanical properties. In this paper, the experimental investigations made on the chromium based alloy 3Cr12 (1.4003) in order to characterize its mechanical behavior are presented. During the research, a classical uniaxial experimental equipment and a bi-axial experimental equipment designed by Flores (2005) [1] in the Structures Laboratory of the University of Liege have been used. The collection of tests performed included tensile tests, cyclic shear tests, simple shear tests and successive simple shear and plane-strain tests. The yield locus and the hardening models are presented and identified in a companion paper by the same author.