微机在万能液压材料试验机测绘系统中的应用

简述了对600kN万能液压材料试验机测绘系统进行微机数字化测量系统的改造的基本原理，系统构成和技术要求，解决了主要的问题，并对关键技术的解决和实现，系统特点作了说明。     

关于加快发展现代物流业的思考

加快发展我国物流产业 ,可以全面提升我国企业的国际竞争实力。搞好现代物流业对我国的经济发展具有重要作用。通过分析物流的基本涵义以及现代物流的发展趋势 ,提出在我国入世之后 ,应如何全面提高我国物流管理水平的重要性 ,以及在当前物流发展中存在的问题。     

浅谈隐性课程的作用

隐性课程不是通过正式教学进行的,通常体现在学校和班级的情境之中。它包括物质情境、文化情境、人际情境,对学生起潜移默化的影响。开发与利用隐性课程对英语学习是十分重要的。     

Resource Flexibility Issues in Multistage Manufacturing

We test the situational impact of two types of resource flexibility, machine flexibility and labor flexibility, in a material requirements planning (MRP)-driven production system. Machine flexibility has not been treated in prior multistage research, only labor flexibility. Machine flexibility is closely related to a plant's positioning strategy. A process-focused plant opts for considerable machine flexibility by choosing general-purpose equipment. Resource flexibility, if effective, can be an attractive alternative to two other types of buffers, inflated inventories and costly capacity cushions. Our simulation results, using factor settings established earlier by a panel of managers, show that resource flexibility is indeed an effective buffer against uncertainties such as end-item demand variability, capacity bottlenecks, equipment failures, and yield losses. Machine flexibility is especially helpful in environments characterized by high uncertainties, tight capacities, and large lot sizes. Worker flexibility has a similar, but less dramatic, impact. Benefits are most striking with customer service, rather than with inventory or labor productivity. Finally, we show that simultaneous introduction of both machine and labor flexibility yields only marginal improvements over either kind of flexibility alone.     

SOME COMMENTS ON “A SYSTEMS PERSPECTIVE ON MATERIALS REQUIREMENTS PLANNING”*

We believe there are some serious deficiencies in the Morecroft article on MRP problems which appeared in a recent issue of this journal. The article, at the most, shows that MRP, inappropriately imposed on an existing production system, can result in undesirable system performance. This does not represent a new or startling conclusion. Four problem areas in the article are discussed, and suggested alternative approaches are offered.     

AN ANALYSIS OF CAPACITY PLANNING PROCEDURES FOR A MATERIAL REQUIREMENTS PLANNING SYSTEM*

This paper is concerned with planning work-center capacity levels in manufacturing firms that employ a material requirements planning (MRP) system. It presents four procedures for developing work-center capacity plans designed to insure the production of components and assemblies as specified by the MRP plan and the master production schedule (MPS). These procedures (capacity planning using overall factors, capacity bills, resource profiles, and capacity requirements planning) are compared using simulation analysis. The results indicate that the performance of a procedure when measured against the MPS depends on the operating conditions of the manufacturing system. The results also indicate that the choice of a particular procedure often represents a compromise among the benefits of improved MPS performance, the costs of preparing and processing data, and the premium expenses required for more frequent adjustments in work-center capacity levels.     

论科学发展观与我国生态经济学的发展

在分析生态经济学理论优势的基础上,提出一个人口、生产和消费与生态环境关系的研究框架。研究重点主要是在短期内从生产的角度进行生态补偿研究,而长期必须从消费偏好的角度进行研究。在研究方法上,应该借鉴条件价值法、生态足迹和物质流会计、新制度经济学等方法。这样才能使生态经济学走出乌托邦式的哲学范式,接近公众从而找到其动力源泉。     

对保障措施制度的法经济学分析

保障措施是一项贸易保护手段,它服从于各国调整和发展本国经济的需要,其目的在于防止本国产业受到损害。尝试运用法经济学的分析方法,对实施该项措施后产生的后果与影响进行初步的考察。     

Efficient Heuristics for MRP Lot Sizing with Variable Production/Purchasing Costs*

Two heuristics based on branch and bound (B&B) are developed to solve closed-loop material requirements planning (MRP) lot-sizing problems that have general product structures and variable costs. A “look ahead method'’(LAM) heuristic allows for variable production/purchasing costs and uses a single-level B&B procedure to rapidly improve lower bound values; thus, LAM efficiently uses computer-storage capacity and allows solution of larger problems. The “total average modification'’(TAM) heuristic uses B&B, applied level by level, and modified setup and carrying costs to solve the variable production/purchasing costs MRP lot-sizing problem. LAM and TAM are tested on problems and compared to heuristics in the literature. TAM may be used to solve large MRP lot-sizing problems encountered in practice.