Material planning with uncertain product quality†

Traditional material requirement planning (MRP) is a system procedure to determine input quantities and ordering times to meet a specified demand in a deterministic framework. A variety of modifications to MRP have been proposed to incorporate different forms of uncertainty in production systems. In this paper, wc consider the case where the uncertainty is due to quality variations in the production process, and we develop an approach which links material planning with quality variations and control.     

Object-oriented design of a distributed agent-based framework for e-Procurement

Procurement is an important function in any manufacturing organization and it also has strategic business value attached to it. Hence, any improvements in the process would result in tremendous benefits. E-Procurement exploits the Internet and agent technologies to conduct procurement-related processes. In this paper, we design and develop a software agent-based framework for a typical e-Procurement process by decomposing it into three business processes: e-Negotiations, reverse auctions and e-Settlement. The artefacts of the system for each of the three business processes have been designed and developed using Unified Modeling Language (UML). A prototype of one of the processes, viz. reverse auction, has also been implemented.     

A Probabilistic Approach for Deriving Acceptable Human Intake Limits and Human Health Risks from Toxicological Studies: General Framework

The use of uncertainty factors in the standard method for deriving acceptable intake or exposure limits for humans, such as the Reference Dose (RfD), may be viewed as a conservative method of taking various uncertainties into account. As an obvious alternative, the use of uncertainty distributions instead of uncertainty factors is gaining attention. This paper presents a comprehensive discussion of a general framework that quantifies both the uncertainties in the no-adverse-effect level in the animal (using a benchmark-like approach) and the uncertainties in the various extrapolation steps involved (using uncertainty distributions). This approach results in an uncertainty distribution for the no-adverse-effect level in the sensitive human subpopulation, reflecting the overall scientific uncertainty associated with that level. A lower percentile of this distribution may be regarded as an acceptable exposure limit (e.g., RfD) that takes account of the various uncertainties in a nonconservative fashion. The same methodology may also be used as a tool to derive a distribution for possible human health effects at a given exposure level. We argue that in a probabilistic approach the uncertainty in the estimated no-adverse-effect-level in the animal should be explicitly taken into account. Not only is this source of uncertainty too large to be ignored, it also has repercussions for the quantification of the other uncertainty distributions.     

佃农理论与南京大学

有关土地使用的合约问题一直是有争议的。以往学者们从传统理论上分析,总是认为租佃制是无效率的。可是他们不能解释为什么类似于租佃制的合约方式在近现代还很有生命力。从南京大学获得的各种土地合约的原始资料可以发现相反的结论,说明租佃制是有效率的。这些合约资料帮助我完成了博士论文,并使得我的论文更加精彩。经济学是解释现象的,我们应该解释那些现实的东西,而不应该只解释并不存在的东西。     

Residual‐Based Block Bootstrap for Unit Root Testing

A nonparametric, residual‐based block bootstrap procedure is proposed in the context of testing for integrated (unit root) time series. The resampling procedure is based on weak assumptions on the dependence structure of the stationary process driving the random walk and successfully generates unit root integrated pseudo‐series retaining the important characteristics of the data. It is more general than previous bootstrap approaches to the unit root problem in that it allows for a very wide class of weakly dependent processes and it is not based on any parametric assumption on the process generating the data. As a consequence the procedure can accurately capture the distribution of many unit root test statistics proposed in the literature. Large sample theory is developed and the asymptotic validity of the block bootstrap‐based unit root testing is shown via a bootstrap functional limit theorem. Applications to some particular test statistics of the unit root hypothesis, i.e., least squares and Dickey‐Fuller type statistics are given. The power properties of our procedure are investigated and compared to those of alternative bootstrap approaches to carry out the unit root test. Some simulations examine the finite sample performance of our procedure.     

Defining Spirituality of Work

There is a current surge of writings on spirituality and related topics. For instance, Woodward (1997) has pointed out that since Thomas Moore's publication of Care of the Soul in 1994 there have been nearly 800books published with the word soul in the title. These run all the way from Chicken Soup for theWoman's Soul (Canfield et al., 1996) to A Guide to Liberating YourSoul (Barrett, 1995). Spirituality of work is a big part of this surge. Definitionsof spirituality of work seem to vary widely. Bowman (1998, p. 8) in his `reviewof the phenomenon of spirituality of work' found `Definitions of the term spirituality in the context of the Spirituality of Work troublesome and particularly subjective. Many writers do not even attempt definitions.' The purpose of this article is to review the concept of spirituality of work in its historical and current use and to propose a comprehensive definition.