An oracle-based algorithm for robust planning of production routing problems in closed-loop supply chains of beverage glass bottles

The demand for glass bottles is exhibiting an upward trend over time. The manufacturing of glass bottles is costlier in terms of time and resources and is associated with a higher level of heat generation and environmental pollution compared to recycling processes. In response to the aforementioned challenges, companies that use glass bottles need to implement strategies to manage their reverse supply chains in conjunction with their traditional supply chains, as the economic and environmental benefits of returned products are unquestionable. Closed-loop supply chains (CLSCs) integrate forward and reverse flows of products and information. This integration helps companies to have a broader view of the whole chain. Despite these advantages, managing CLSCs can be challenging as they are exposed to many uncertainties regarding supply and demand processes, travel times, and quantity/quality of returned products.In this study, we consider the production planning, inventory management, and vehicle routing decisions of a CLSC of beverage glass bottles. We propose an MILP model and rely on a multi-stage adjustable robust optimization (ARO) formulation to deal with the randomness in both the demand for filled bottles and the requests for pickups of empty bottles. We develop an exact oracle-based algorithm to solve the ARO problem and propose a heuristic search algorithm to reduce the solution time. Our numerical experiments not only show the incompetency of the customary method, namely the affine decision rule approach, but also illustrate how our algorithms can solve the small-size problems and significantly improve the quality of the obtained solution for large problems. Furthermore, our numerical results show that robust plans tend to be sparse, meaning the routes are chosen so that empty bottles are transported to production sites in such a way that fewer new bottles need to be ordered. Thus, robust planning makes the CLSCs more environmentally friendly.     

医学统计学教学改革刍议

针对目前医学统计学教学中存在的问题，从教学内容的调整、教学方法的改进、教学手段的更新等方面入手。探讨如何提高医学统计学的教学质量，目的在于使医学生能够更好地掌握统计学这门学科，成为合格的医学人才。     

Unemployment duration and the measurement of unemployment

We propose a framework in which the welfare bases of various unemployment measures available in the literature can be analyzed and a decomposition of these measures can be made into aggregate unemployment and the concentration of its distribution. A set of axioms for an unemployment measure is then introduced, which relate to the sensitivity of an unemployment measure to the inequality in the distribution of the unemployment. An unemployment measure is derived on the basis of these axioms that captures the distributional considerations in the measurement of unemployment.      

具有不确定的时滞微分系统的稳定性

研究具有不确定的时滞微分大系统的鲁棒稳定性问题，利用李雅普诺夫函数和不等式分析方法，给出了不确定性时滞微分大系统在不依赖时滞的反馈分散控制下是稳定化的、渐近稳定化和指数稳定化的充分条件。     

Enrolment in initial courses in statistics: An exploratory study

In January 1981 a questionnaire was sent to 102 universities and colleges in Canada and the United States seeking information on enrolment in initial courses in statistics. That questionnaire has been analyzed and the results are presented in this paper.     

《醒世恒言》被动句式考察

对《醒世恒言》中的被动句式进行分类统计,从用量及结构等方面探讨“于”字式、“见”字式、“为”字式和“为……所”式这些上古汉语传统模式的衰微、“被”字式在近代汉语中的进一步发展以及“教”字式、“与”字式、“吃”字式这些近代汉语才产生的被动式的特点,从而阐述被动句式在近代汉语中的发展概貌。     

统计学发展过程中四次重要的争论及其影响

统计学发展过程中出现过几次重大的争论,这些争论在本质上可以说是一脉相承的。"政治算术"与"国势学"的争论,明确了统计学的学科性质;"描述统计学"与"推断统计学"的争论,构筑了统计学的完整体系;"经典统计学"与"贝叶斯统计学"的争论,带来了统计哲学观的新变化;信念统计学与经典统计学、贝叶斯统计学的争论,使统计推断科学化问题的研究日趋深入。正是通过这些争论完善了现代统计学的思想和方法体系。     

当代大学生媒介消费行为统计分析

当今世界信息传播革命正在兴起,信息技术的迅猛发展推动着大众传播媒介走向现代化。大众传播媒介的发展对大学生的影响尤为深刻。本文拟对当代大学生对大众传播媒介的使用状况作粗浅探索和分析,并试图研究互联网的使用与其它传播媒介的关系。     

Asymptotic distributions for the intervals estimators of the extremal index and the cluster-size probabilities

Under appropriate long range dependence conditions, the point process of exceedances of a stationary sequence weakly converges to a homogeneous compound Poisson point process. This limiting point process can be characterized by the extremal index and the cluster-size probabilities. In this paper we address the problem of estimating these quantities and we consider the intervals estimators introduced in Ferro and Segers [2003. Inference for clusters of extreme values. J. Roy. Statist. Soc. Ser. B 545–556] and in Ferro [2004. Statistical methods for clusters of extreme values. Ph.D. Thesis, Lancaster University]. We establish asymptotic weak convergence to Gaussian random variables and we give their asymptotic variance.     

基于稳健稀疏主成分的经济增长影响因素分析

从传统生产要素、制度、金融和经济结构等四个方面选取了19个影响中国经济增长的变量,运用稳健稀疏主成分方法进行实证分析。结果表明物质资本、城镇化率、金融深度、城镇居民消费结构、基尼系数、技术水平已成为促进中国经济增长的主要动力,但东、中、西部经济增长的主要影响因素互不相同。在此基础上就如何进一步促进中国经济增长和区域经济均衡发展提出了若干政策建议。