Open Order Rescheduling in Job Shops with Demand Uncertainty: A Simulation Study

This paper addresses the problem of open order rescheduling in a job shop. Results are reported of experiments conducted in a simulation model of an 8-machine job shop. Four different order updating policies are examined. The due-date process is modeled to include several realistic features about the pattern of due-date variability. These features are parameterized and tested at several levels. Tardiness results indicate that open order rescheduling is beneficial only when allowances are loosely set. The results indicate that inventory performance is improved by order rescheduling, particularly in cases when due dates are revised to earlier times than originally forecast.     

浅谈专业课的教学

专业课教学中的趣味性及授课方式的巧妙性,能激发学生的学习兴趣,营造轻松、愉快的学习氛围。     

土壤污染刑事责任探究

土壤污染是制约生态农业发展的罪魁祸首。制定《土壤污染防治法》对污染土壤的行为进行惩治,无疑是解决问题的一种最为有效的途径。立法最重要的问题是责任的明晰。法律责任有行政责任、民事责任和刑事责任,土壤污染刑事责任应当有别于其他污染。在立法模式上,土壤污染的刑事责任应当既在刑法中规定,也在土壤污染防治法中进行规定。     

The impact of learning opportunities and decision authority on occupational health

In an investigation of 418 employees in the Norwegian Postal Service, employees with high learning opportunities and high decision authority were found to be better off on psychological functioning, health and organizational outcome variables than employees with low scores on these variables. Decision authority and learning opportunities had specific and independent impact on subjective health, psychological functioning, coping style and organizational outcome variables. There were, however, also interaction effects between demands, learning opportunities, and decision authority on subjective health. Learning opportunities and decision authority were operationalized with a questionnaire, supplemented with questions on the opportunities to learn skills beyond the present job situation. It is suggested that this is a particularly important dimension for coping with the present day rapid changes in working life, where the objective for many workers will be to broaden their repertoire and competence to increase their flexibility in the labour market.     

Neural networks in production planning and control

The purpose of this paper is to present a selection of the most significant ANN (artificial neural network) applications used to solve PPC (production planning and control) problems. Therefore, the paper itself is a reasoned classification rather than a simple survey. The PPC domain is divided into various areas, and for each area one or more examples of ANNs are discussed, together with the benefits and drawbacks of their application to that particular area. Finally, two case studies developed by the authors are reported and discussed to analyse the main implementation problems to be considered when using ANNs.     

Shop floor control system for tool rooms

A shop floor control system (SFCS), which is the most important component of any production control system, ff has a direct e ect on the productivity of a tool room. The SFCS presented in this paper aims at streamlining various tool room activities, such as process planning, operations scheduling, loading, progress monitoring, and performance monitoring. The system discussed in this paper is characterized by simplicity and is user friendly. Basic information, consisting of three types of information (order details, process details, and part details), is input through interactive dialogue sessions. On-line updating of the process information is carried out, again through interactive dialogue sessions. The basic input to the system along with the on-line updating enables a number of useful and important reports and documents to be generated ff by the system for e ective control of the shop floor. The reports generated include operations scheduling, process sheet, part list, ffi job card, load pending report, e ciency report, etc. This SFCS is developed for a medium sized tool room in an automotive company and its successful implemention reduced paperwork and improved resource management and has resulted in productivity. It can be said that this system offers a first venture into computer integrated manufacturing (CIM) for a tool room.     

Age at First Marriage and Age at Death in the Lincolnshire Fenland, 1252–1478

In five Lincolnshire villages between 1252 and 1478 there is evidence that men and women married fairly late before the Black Death, and that by 1348/9 the Western European marriage pattern of late and prudential marriage was well established. Households were usually nucleated; husbands were on average eight years older than their wives before 1348/9, and five years older after 1348/9. Marriages were short: according to the best calculation shorter before 1348/9 than after, most often terminated by the death of the first husband, and were unlikely to produce more than three children. Since there were more males than females amongst children and young adults, many men remained unmarried, but since the death rate of women was very high, men lived longer.     

Decentralized WIP-oriented manufacturing control (DEWIP)

DEWIP is a manufacturing control system for job shop environments aiming at achieving short and reliable lead times by establishing WIP control loops between the manufacturing work centres. The paper describes the mode of function, the setting of parameters and simulation results of the new manufacturing control system. The setting of parameters is done with the aid of the funnel model and the theory of logistic operating curves, both developed at the Institute of Production Systems at the University of Hanover. The simulation is conducted using industrial data and makes it possible to assess DEWIP with regard to lead times, WIP level, performance and schedule reliability. DEWIP is compared both with an uncontrolled process and with the manufacturing control systems Load oriented order release (LOOR), Conwip and Polca. The results suggest that DEWIP and the models employed for the setting of parameters are suitable for job shop production and therefore offer a valuable alternative to prevailing centralized manufacturing control systems.     

国有商业银行信贷资产风险分析及控制研究

在现阶段社会信用程度依然低下 ,形形色色的政府干预依然存在 ,现代商业银行制度尚未建立和完善的背景下 ,我国国有商业银行信贷资产风险的控制将是一项艰巨而复杂的系统工程。文章通过剖析信贷资产风险形成的内外部因素 ,阐述了信贷资产风险的形成机制 ,提出了控制信贷资产风险的针对性措施。