多模态静力推覆分析及其在高层混合结构体系抗震评估中的应用

在已有的研究基础上通过考虑多阶振型质量积的水平力分布形式下的推覆分析,将结构推至每阶振型下的目标位移,采用SRSS组合的方式得到结构的响应.对应每阶振型下推覆分析的目标位移采用弹塑性反应谱来计算.对一高层钢框架-混凝土核心筒混合结构在7度罕遇地震下抗震性能进行了评估,结果显示,多模态静力推覆分析所得的结构响应同非线性动力时程分析所得结果很接近,尤其是在层间位移角及层间剪力这两个重要抗震指标上更为接近.     

MULTI-PROJECT SCHEDULING WITH EXPLICIT LATENESS COSTS

We propose a heuristic procedure for planning and scheduling multiple projects subject to limited resource availabilities. We depart from previous research in that explicit lateness costs for each project are considered. Our procedure involves aggregate analysis using linear programming to determine target resource loading profiles for each project that optimize trade-offs of lateness costs among projects, followed by detailed multi-project scheduling consistent with the target profiles. Target profiles and detailed schedules are iteratively modified through N iterations, where N is the number of projects. The procedure can be used to jointly schedule previously committed and newly proposed projects, as well as to assign due dates to proposed projects. We compare the performance of our procedure to that of the traditional minimum slack heuristic, as well to a simple extension of the minimum slack rule that accounts for lateness costs. On a set of 60 multi-project test problems adapted from the Patterson set of single-project problems, results are very favorable for our proposed algorithm.     

PARALLEL-MACHINE SCHEDULING WITH FRACTIONAL OPERATOR REQUIREMENTS

This paper discusses the fractional operator problem, which involves the production of many parts on several parallel machines. In this problem, operators can monitor more than one adjacent machine subject to the operator requirements of the parts being produced on those machines. Thus, the combination of parts being produced determines the number of operators required. We consider minimizing the average setup and holding costs subject to a constraint on the number of operators available. We describe planning- and control-level versions of the problem and give formulations that provide a basis for future work.     

MATHEMATICAL ANALYSIS OF FACILITY-COMMODITY SCHEDULING PROBLEMS

A number of operational situations exist in which certain facilities are available and where a number of commodities must be processed on some or all of these facilities. The paper describes an algorithm to generate schedules which are near optimal or optimal with respect to the total processing time of all the commodities, the idle lime of facilities and production rate. Thus, these schedules are characterized by near minimal or minimal total processing time and idle time of facilities and near maximal or maximal production rate. Usually this algorithm does not result in the desired schedule after the first application; it is therefore proposed to generate a set “D” of schedules from which the desired schedule can be selected. A decision rule determines the optimal number of elements belonging to set D

In order to justify the concept of the algorithm for the determination of the schedules mentioned above, an analysis is given of the decision tree associated with the sequencing model in terms of the probabilities related to the nodes in the decision tree.     

超薄单向纤维增强复合材料低频多模式超声兰姆波定征方法

提出低频多模式超声兰姆波定征方法来估计超薄层状单向纤维增强复合材料的密度、厚度、弹性常数等参数。这里"超薄"的概念是指材料厚度h远小于材料中的声波波长λ,导致在时域上材料前后界面的各次回波信号相互混迭。分析了沿平行和垂直于纤维两个方向上,在超薄层状单向纤维增强复合材料中传播的低频兰姆波色散特性,提出在最小二乘意义下以材料色散曲线为基础的反向算法对材料参数进行了估计。文中分析了影响估计准确性的各种因素,研究了该方法对材料参数的灵敏度及其在误差传递中的意义。结合超声漏兰姆波频域分析方法,并使用超声耦合剂耦合方式和一对中心频率为2MHz的宽带纵波换能器,实验结果证实,该方法能够准确估计h<0.05 λ的单向玻璃纤维增强双酚A型聚砜(PSF)复合材料的材料参数。      

项目和产品

上海戏剧学院浦江校区 设计：加拿大CPC建筑设计顾问有限公司 项目类型：文化建筑建筑 面积：162．000m^2 占地面积：59．500m^2 项目进度：竞标中     

A MODIFIED DECOMPOSITION ALGORITHM FOR SCHEDULING PROBLEMS

A decomposition approach developed by the author is modified to reduce the computational effort involved. The modified algorithm is discussed. Computational experiments have been conducted for comparative evaluation of both original and modified decomposition algorithms. Significant results are reported.     

ROBOT TASK SCHEDULING IN A FLEXIBLE MANUFACTURING CELL

Effective sequencing and scheduling of the material handling system can have a major impact on the productivity of the manufacturing system. This is especially true in the case where material handling times are on par with machine processing times. In a dynamic, real-time environment, the optimal solution of this scheduling problem may be computationally infeasible.

In this paper, we develop a branch and bound approach which is coupled with quick, effective bounds to optimize the movement of a robot which serves the material handling requirements within a manufacturing cell. Computational results are given which explore the tradeoff between computation time and deviation from optimal for different scenarios.     

A DECOMPOSITION APPROACH FOR THE MACHINE SCHEDULING PROBLEM

This paper investigates the solution of the machine scheduling problem by a decomposition approach. The original problem is partitioned into a series of smaller, more manageable sub-problems. Considerable experimentation is conducled to study the statistical characteristics of this approach and to compare results with those obtained by complete or partial enumeration. The relative efficiencies of the decomposition solutions are investigated. The hypothesis that the mean of the schedule times shifts toward the minimum as the number of jobs in each sub-problem increases is tested. Finally, the computer times spent to obtain the complete or partial enumeration and decomposition solutions are compared.     

PRODUCTION SCHEDULING IN A FLEXIBLE MANUFACTURING SYSTEM WITH SETUPS

A model is presented for the planning and scheduling of production batches in a flexible manufacturing system environment in which setup costs and times are nonnegligible and alternate routings are possible. The formulation is an integer program with a multicommodity flow network structure. A heuristic procedure based on price-directive decompostion using column generation is used to obtain solutions. Numerical experimentation is performed to assess die quality of the heuristic versus optimal solutions, and to determine the impact of routing flexibility on total cost, inventory levels, bottlenecks, capacity utilization, throughput time, number of setups and split lots. Important cost-benefit trade-off implications are shown for the design of flexible manufacturing systems.     

NOTE ON INTRODUCTION OF GASH FLOW INTO CRITICAL PATH SCHEDULING

This note describes a study which was completed recently to determine whether components should be manufactured in the user's plant rather than purchased. The Critical Path Technique and the Requirements Planning Network were of assistance in developing the general purpose model.     

SIMULATION OF AN ACTUAL PRODUCTION SCHEDULING AND WORK FLOW CONTROL SYSTEM

This paper is a progress report on a study of an actual decision-making system. It scrutinizes the demands made on a manufacturing organization and the responses of the organization to these demands

The study focuses on the ways the organization got a particular job done, namely the job of production scheduling and work-flow smoothing in the box-making plants of a manufacturer of shipping containers. The complete system can be factored into two parts. One sub-system places orders in sequence and prepares an advance production schedule. The second subsystem controls the flow of work through the actual manufacturing operations, making final adjustments in the sequence and speed of the work-flow.     

A STATIONARY CYCLICAL PRODUCTION SCHEDULING PROBLEM UNDER A NONADDITIVE OUTPUT FUNCTION

The purpose of this paper is to formulate and solve a nonlinear mixed zero-one integer programming problem aimed to maximize total output by scheduling the operational time of N non-identical machines. Properties of the optimal solution are identified under restrictions imposed on machine availability and various budget constraints. A branch and bound algorithm to solve the problem is suggested.     

A ROLLING HORIZON HEURISTIC FOR REACTIVE SCHEDULING OF BATCH PROCESS OPERATIONS

Batch chemical plants are dynamic processing facilities where static production schedules can rarely be adhered to due to market and operating uncertainties. On-line schedule modification of a prior; timing assignments and resource allocations in response to unantipicated disruptions is done through a decomposition heuristic that uses a rolling horizon implementation policy. An attempt is made to minimize the impact of the disruptions on the original schedule near the point of each deviation while exploiting the combinatorial flexibility of task and resource reassignments in future scheduling time windows. The problem is addressed as a multiobjective optimization problem involving completion time criteria, relative customer importance, and production cost considerations.

A rigorous analysis of problem sensitive parameters, including penalty weights and subhorizon length, is conducted. A model plant case study is performed. Variations on storage availability and task flexibility are investigated in an attempt to characterize dominant effects of the weighting parameters. Results indicate that user preference can serve as a strong guide for obtaining near optimal reactive scheduling solutions. It is shown that the combinatories can be controlled and that costly and inefficient full scale rescheduling of multipurpose production facilities can be avoided.