Acquisition of Telecommunications Bandwidth Under Economies of Scale in Size and Duration of Contracts*

Significant advances in information technology have brought about increased demand for bandwidth. Buyers of bandwidth often encounter bandwidth prices that are decreasing over time. Additionally, bandwidth prices at any point in time are decreasing in total bandwidth purchased and length of contracts. Therefore, buyers face complex decisions in terms of the number of contracts to buy, their bandwidth, and their lengths. In this article, we formulate models for the acquisition of bandwidth from a buyer's perspective. We begin with a model that allows varying contract durations under deterministic demand and without allowing shortages or overlapping contracts. We then formulate a simpler model, which restricts contract lengths over the planning horizon to be equal. We also solve the problem under probabilistic demand and allowing for shortages, which are satisfied by buying additional bandwidth at a premium. We perform numerical sensitivity analysis to compare the results of the models and illustrate the results with numerical examples. The numerical analyses illustrate that using relatively simple equal‐length contracts produces approximately the same results as the more complicated unequal‐length contract strategy.     

阿玛蒂亚·森的正义观——对罗尔斯的批判及其公共政策含义

罗尔斯的思考模式并不是理解正义的唯一路径,阿玛蒂亚.森的《正义观》对罗尔斯展开了全面的批判。不同于很多学者忽略替代性理论的完善,阿玛蒂亚.森完成了包括基本主题、分析工具和评估尺度在内的范式转换。他重拾了智识史上的现实比较传统取代主流的先验制度主义,发展了社会选择理论以代替契约论分析构架,以能力尺度超越了基本物品尺度。阿玛蒂亚.森在基本主题和分析工具的学术合法性的证明上是完整和有说服力的,而在将能力方法(作为评估尺度)运用于公共政策领域时则面临了理论逻辑和现实逻辑的限制。只有在理论上退让到基本能力层面,能力方法才具有公共政策中的合理性。与罗尔斯的《正义论》一样,阿玛蒂亚.森的《正义观》也不可能是正义研究的终点,两种范式之间的争论方兴未艾。     

师范院校高等代数课程教学的几点认识

师范院校高等代数课程教学中如何提高教学质量,使学生通过这门课的学习获得相应的知识和能力,谈几点认识。     

市场经济与中国共产党执政能力建设

市场经济对中国共产党来说是一个全新的课题。不断提高党驾驭市场经济的能力是加强党的执政能力的重要内容,也是关系着党执政合法性的大问题。因此,要正确处理驾驭市场经济能力与党执政的合法性、党的先进性及党的奋斗目标之间的关系,并从抓住经济建设中心、坚持市场机制优势与社会主义制度优越性的结合、进一步完善党领导经济工作的体制、机制和方式等等方面去加强党驾驭市场经济的能力建设。     

我国科学技术创新能力不足之原因

我国当前科学技术创新能力不足的根本原因是科学工作者缺乏西方科学所具有的哲学思想、文化基因和教育环境,提升中国科学技术创新能力的关键是加强西方哲学思想的学习和熏陶,加大教育改革力度,推行多元化教育;崇尚理性主义精神等。     

A new generation of process capability indices based on fuzzy measurements

Process capability indices (PCIs) provide numerical measures on whether a process conforms to the defined manufacturing capability prerequisite. These have been successfully applied by companies to compete with and to lead high-profit markets by evaluating the quality and productivity performance. The PCI C_p compares the output of a process to the specification limits (SLs) by forming the ratio of the width between the process SLs with the width of the natural tolerance limits which is measured by six process standard deviation units. As another common PCI, C_pm incorporates two variation components which are variation to the process mean and deviation of the process mean from the target. A meaningful generalized version of above PCIs is introduced in this paper which is able to handle in a fuzzy environment. These generalized PCIs are able to measure the capability of a fuzzy-valued process in producing products on the basis of a fuzzy quality. Fast computing formulas for the generalized PCIs are computed for normal and symmetric triangular fuzzy observations, where the fuzzy quality is defined by linear and exponential fuzzy SLs. A practical example is presented to show the performance of proposed indices.     

Supplier Evaluation and Selection Based on Stochastic Dominance: A Quality-Based Approach

Quality has become a major business strategy such that organizations with successful improvement of their products quality can gain productivity, enhance market penetration, achieve great profitability, and strongly sustain their competitive advantages. The quality of materials received from suppliers determines not only the quality of assembled products but also satisfaction and loyalty of downstream customers. In this article, we employ decision-making processes of the stochastic dominance on the basis of loss-based capability indices to compare certain potential suppliers. In view of compared results of the first-order and second-order stochastic dominances, each supplier is categorized as a superior supplier, weakly superior supplier, strongly non dominated supplier, or non dominated supplier. We develop a general computational procedure to select the preferable suppliers in an analytical way. To assist decision-makers in selecting preferable suppliers, quantile-quantile plots of loss-based capability indices presenting the results of the first-order stochastic dominance of the indices’ estimators are developed so that they can simultaneously visualize pair-wise comparisons of the suppliers and make appropriate decisions. Finally, a practical example invoking the stochastic dominance using the loss-based capability indices to carry out the quality-based supplier evaluation and selection is presented to demonstrate the applicability of our proposed methodology.     

On the generalized process capability under simple and mixture models

Process capability (PC) indices measure the ability of a process of interest to meet the desired specifications under certain restrictions. There are a variety of capability indices available in literature for different interest variables such as weights, lengths, thickness, and the life time of items among many others. The goal of this article is to study the generalized capability indices from the Bayesian view point under different symmetric and asymmetric loss functions for the simple and mixture of generalized lifetime models. For our study purposes, we have covered a simple and two component mixture of Maxwell distribution as a special case of the generalized class of models. A comparative discussion of the PC with the mixture models under Laplace and inverse Rayleigh are also included. Bayesian point estimation of maintenance performance of the system is also part of the study (considering the Maxwell failure lifetime model and the repair time model). A real-life example is also included to illustrate the procedural details of the proposed method.     

中国学习者BECAUSE原因状语从句习得初探

原因状语从句是中国学习者在英语写作中常用到的结构。采用语料库研究方法研究中国学习者对because原因状语从句的习得,以中国学习者英语语料库(CLEC)及其各个子库(ST2、ST3、ST4、ST5、ST6)作为研究对象,参照Brown语料库,对各个语料库中由because引导的原因状语从句进行检索—分类标注—分类检索—对比—分析。研究表明由于受到母语负迁移作用的影响,中国学习者将because原因状语从句置于主句之前的比率高于以英语为母语的使用者,初步验证了随着学习者习得水平的提高,将because原因状语从句置于主句之前的情况越少,出现because与so连用表达因果关系之类的言语失误率也越低。     

应用全面创新管理提高中小型企业创新能力研究

在全球抗争危机中创新型企业(包括中小型企业)表现出了其独赋的优势,而中小型企业在其转型和升级中也需要借助全面创新管理提升其创新能力.本文首先探讨了什么是创新型企业;继而讨论了如何走向创新型企业及其三个阶段:"二次创新--组合创新--全面创新";紧接着对全面创新管理的内涵、特征做了较详讨论.然后对本专辑的论文安排结构作了简要介绍.