Setups and effective capacity: the impact of lot sizing techniques in an MRP environment

This study investigates how lot sizing techniques influence the profit performance, inventory level, and order lardiness of an assembly job shop controlled by MRP. Four single-level lot sizing techniques are compared by simulation analysis under two levels of master schedule instability and two levels of end item demand. A second analysis investigates the influence of a multilevel lot sizing technique, the generalized constrained-K (GCK) cost modification, on the four single-level techniques at low demand and low nervousness. The analyses reveal a previously unreported phenomenon. Given the same inventory costs, the single-level lot sizing techniques generate substantially different average batch sizes. The lot sizing techniques maintain the following order of increasing average batch size (and decreasing total setup time):

economic order quantity (EOQ)

period order quantity (POQ)

least total cost (LTC)

Silver-Meal heuristic (SML)

The causes for different average batch sizes among the lot sizing techniques are analysed and explained. Demand lumpiness, inherent in multilevel manufacturing systems controlled by MRP, is found to be a major factor. The number of setups each lot sizing technique generates is the primary determinant of profit performance, inventory level, and order tardiness. EOQ, a fixed order quantity technique, is less sensitive to nervousness than the discrete lot sizing techniques. EOQ_, however, generates the smallest average batch size, and, therefore, the most setups. Since setups consume capacity, EOQ, is more sensitive to higher demand. SML generates the largest average batch sizes, and is, therefore, less sensitive to increased demand. At low demand, the other lot sizing techniques perform better on all criteria. They generate smaller batches and, therefore, shorter actual lead times. The GCK cost modification increases the average batch size generated by each lot sizing technique. GCK improves the profit and customer service level of EOQ the lot sizing technique with the smallest batches. GCK causes the other lot sizing techniques to generate excessively large batches and, therefore, excessively long actual lead times.     

An evaluation of the tandem configuration automated guided vehicle system

The performance of a tandem automated guided vehicle (AGV) system is compared with that of conventional AGV track systems. In the tandem system the track is divided into non-overlapping, single-vehicle closed loops. Using simulation it is shown that, because of trips requiring delivery across loops, the tandem system has a higher expected travel time per load and thus a greater average time in system. When the loads are delivered within the original loop only, the tandem system has a lower average time in system than in conventional systems, although the difference is modest. Track layout appears to influence the average time in system much more than docs the dispatching rule invoked. The success of the tandem system is highly dependent on approximately even AGV utilization, which may be difficult to obtain in practice.     

Responsive Public Officials and Engaged Citizens: Myth or Reality? A Case Study of Water Rights Policy in Colorado

In the past decade nearly 20 Colorado communities have constructed kayak courses to provide recreational amenities and attract tourists. These projects were followed in some cases by applications for a new form of recreational water rights, which differs dramatically from traditional forms of water rights in Colorado. This paper investigates the role that citizens played in the legal and legislative battles that resulted in this policy change. Findings indicate that citizens demanded the construction of kayak courses across Colorado, to which local officials responded. Citizens generally were indifferent to water rights applications once kayak facilities were constructed, however. Government officials sought the water rights to protect their economic investment and their newfound tourist revenue.

创业投资利益分割模型研究:基于创业企业家视角的分析

创业企业对创业企业家的激励是否有效决定着创新的成败。为了研究创业投资中的利益分割问题,从创业过程的特征出发,本文首先分析创业企业家的角色特征,应用间接定价理论和交易效率比较,结合委托-代理模型,构造了基于对创业企业家间接定价的创业企业利益分割的两部动态规划模型,并进一步探讨了债权型和股权型利益分割合约的使用条件和创业企业管理团队的选择问题。研究表明:创业企业家和创业资本家的利益分割合约是基于两部动态规划的优化问题;债权型与股权型合约作为利益分割机制对于创业企业家和资本家的效用取决于各自对未来的预期;只有满足一定条件下,创业企业才倾向于选择能力较高的第三方团队充当企业管理者;在能力同等条件下,创业企业倾向于选择创业企业家充当创业企业的管理者。     

对《反杜林论》中世界的物质统一性证明问题的理解

世界的物质统一性原理不仅需要自然科学证明 ,而且需要哲学证明 ,只有马克思主义哲学才是科学的世界观和方法论 ,因此 ,唯有马克思主义哲学才是世界物质统一性的科学的哲学证明     

试论权利与义务在人权上的统一

本文从人权赖以存在的社会事实出发,对人权所具有的权利义务二重性给以阐述,提出人权不仅仅是一项人之为人的权利,更是一项人之为人的义务,是权利与义务的高度统一。这不仅是理论上的论证与事实上的认定,更是我们人类生命本体的内在要求和外在表现,是人权对道德升华的必然要求和结果。     

论对我国弱势群体权利保护的法理思考

弱势群体从法律意义上讲是指在社会转型时期，因社会制度安排等非个人因素而导致的在生存、就业或合法权益保障方面处于弱势地位，需要由国家通过法定形式予以救济的人群共同体。弱势群体“弱势”的实质是权利弱势。弱势群体权利保护的法律理念应为：公平、正义、秩序和发展权。     

An ‘action‐poor’ human rights education: a critical review of the development of human rights education in the context of civic education in Hong Kong

In Hong Kong, human rights education (HRE) is considered an aspect of civic education. For decades, HRE has been poorly attended. In 2009, a new compulsory subject, Liberal Studies, where HRE can be infused, will be introduced to senior secondary students (15–18 years old). This article reviews the development of HRE within civic education, followed by the analysis of Liberal Studies documents with reference to international human rights documents. It is concluded that Liberal Studies can be used as a vehicle for HRE. The aims and pedagogy proposed are similar to those adopted by HRE. International standards of human rights can be incorporated in the content. However, the HRE derived from Liberal Studies is a form of ‘action‐poor HRE’. Whether this ‘action‐ poor HRE’ can adequately cultivate a universal human rights culture is an issue for further research.     

形成权的行使与限制探讨

形成权的权利特征在于单方行使即可发生法律效力，形成权的行使依其条件的不同，会对相对人造成多重影响，也动摇了双方法律关系的稳定性。论文从维护社会法治秩序的角度考虑，提出应在形成权行使的方式特征和结果效力上进行必要的限制，使形成权的行使合理化、规范化。     

金融危机对劳动者权益的影响及保护对策

世界性金融危机对我国经济产生了巨大冲击，经济下滑，企业倒闭、裁员、欠薪、断保甚至雇主欠薪逃匿等问题不断发生。在我国社会保障体制尚不完善的情况下，金融危机对劳动者权益的影响远胜于对企业的影响。在危机应对中，保护劳动者合法权益，关系到我国劳动关系能否和谐稳定的终极目标的实现。一方面要依据国家统一立法，贯彻劳动法倾斜保护的基本原则；另一方面，应当积极推进劳资协商对话机制，使之成为我国劳动者权益保护的主流模式。