重庆汽车产业全产业链发展的现状与思考

重庆作为中国汽车产业都城之一,经过多年发展,汽车产业全产业链不断完善,品牌竞争力不断增强,但同时也出现了诸如产业链不紧密、创新能力不强等现实问题,这为研究重庆汽车产业全产业链提出了迫切要求。文章通过实证分析方法,分析重庆汽车产业全产业链发展现状,从理论与实践角度提出进一步完善重庆汽车产业全产业链的建议。     

县级政府、供应链管理与农产品上行关系研究

基于中国13省87个电子商务进农村示范县的调研材料,分析政府项目驱动下农产品上行问题。实践表明,政策利好为县域农产品电商发展提供了试错空间,“S2B2C”的供应链管理模式对农产品上行的推动作用明显。但是,多数县级政府未能认识到供应链管理之于农产品上行的作用,普遍存在政府治理方式滞后、公共服务网络不健全、农产品区域公用品牌缺乏、冷链等基础设施投入不足等问题。因此,为有效推动农产品上行,政府应进一步推动“公私合作”、构建一体化的公共服务、注重品牌营销、优化产品供应链管理。     

Pharmacovigilance in Clinical Trials: Current Practice and Challenges

In view of the MENA increasing participation in multinational trials and the increasing number of national/regional trials, this article explores potential areas of pharmacovigilance, requiring reform and provides recommendations for building a robust safety reporting system. Regulatory silence on expedited reporting requirements creates confusion for local sites that are part of multinational trials. Not allowing waiver for serious adverse events that are protocol specified or are study endpoints, along with lack of emphasis on causality as reporting criteria, adds substantial burden of uninformative cases for regulatory review. Despite global focus on Development Safety Update Report, local regulators are not yet insistent on real-time update of a drug’s cumulative safety profile. Issues like reporting requirements for generic trials, pregnancy reporting and lenient timeline for death/life-threatening events need attention. Finally, the need to formulate an all-encompassing local pharmacovigilance guideline, in sync with global practice cannot be overemphasized.     

A delay-in-payment contract for Pareto improvement of a supply chain with stochastic demand

We consider a supply chain consisting of a single supplier and a single retailer with stochastic customer demand, which is operated over an infinite horizon. We propose a delay-in-payment contract to coordinate the supply chain. With this contract, the supplier allows the retailer to pay partial order cost at the ordering epoch, and to pay the remaining portion after a permissible number of periods. The system is formulated as a stochastic dynamic programming problem. It is shown that there exists a base-stock policy to be optimal. Compared with the traditional wholesale-price contract, the delay-in-payment contract with appropriate parameters can achieve a Pareto improvement (i.e., the performances of both the supplier and the retailer using the delay-in-payment contract are better than those using the wholesale-price contract). Numerical studies are performed to investigate both the effectiveness of the Pareto improvement, and the impact of the major parameters of the delay-in-payment contract on the system performance.     

Independent attributes control chart for Markov-dependent processes

Statistical process monitoring (SPM) is a very efficient tool to maintain and to improve the quality of a product. In many industrial processes, end product has two or more attribute-type quality characteristics. Some of them are independent, but the observations are Markovian dependent. It is essential to develop a control chart for such situations. In this article, we develop an Independent Attributes Control Chart for Markov Dependent Processes based on error probabilities criterion under the assumption of one-step Markov dependency. Implementation of the chart is similar to that of Shewhart-type chart. Performance of the chart has been studied using probability of detecting shift criterion. A procedure to identify the attribute(s) responsible for out-of-control status of the process is given.     

A harmony search-based memetic optimization model for integrated production and transportation scheduling in MTO manufacturing

This paper investigates an integrated production and transportation scheduling problem in an MTO supply chain. A harmony search-based memetic optimization model is developed to handle this problem, in which certain heuristic procedures are proposed to convert the investigated problem into an order assignment problem. A novel improvisation process is also proposed to improve the optimum-seeking performance. The effectiveness of the proposed model is validated by numerical experiments. The experimental results show that (1) the proposed model can solve the investigated problem effectively and that (2) the proposed memetic optimization process exhibits better optimum-seeking performance than genetic algorithm-based and traditional memetic optimization processes.     

Robustness to non-normality and autocorrelation of individuals control charts

This paper studies the effects of non-normality and autocorrelation on the performances of various individuals control charts for monitoring the process mean and/or variance. The traditional Shewhart X chart and moving range (MR) chart are investigated as well as several types of exponentially weighted moving average (EWMA) charts and combinations of control charts involving these EWMA charts. It is shown that the combination of the X and MR charts will not detect small and moderate parameter shifts as fast as combinations involving the EWMA charts, and that the performana of the X and MR charts is very sensitive to the normality assumption. It is also shown that certain combinations of EWMA charts can be designed to be robust to non-normality and very effective at detecting small and moderate shifts in the process mean and/or variance. Although autocorrelation can have a significant effect on the in-control performances of these combinations of EWMA charts, their relative out-of-control performances under independence are generally maintained for low to moderate levels of autocorrelation.     

广义ATO下基于多种团购模型的供应链协调

针对由多个供应商、单个制造商和零售商所组成的广义按订单装配式供应链，在上游多个供应商不确定的零部件（或商品）供应以及下游客户不确定的需求的环境下，首先分析基本模型中团购前后的零售商和制造商的利润变化，然后提出了团购的标准模型和协调模型，并比较三种不同的团购模型对各成员以及全局供应链绩效的影响。通过数学推导证明和仿真数据算例分析，结果表明：零售商自发的团购基本模型总是对制造商有利，而对零售商的好处是有限的；由制造商主导的团购标准模型在满足一定条件时是优于团购基本模型的，但有使得零售商甚至制造商自身受到损失的可能；而集中决策下的团购协调模型能够提升全局供应链的期望利润，实现渠道的帕累托改善，但协调的效果会受到团购客户组成结构的限制。     

Economic and economic statistical designs for three-level control charts

In some situations, an appropriate quality measure uses three or more discrete levels to classify a product characteristic. For these situations, some control charts have been developed based on statistical criteria regardless of economic considerations. In this paper, we develop economic and economic statistical designs (ESD) for 3-level control charts. We apply the cost model proposed by Costa and Rahim.[Economic design of X charts with variable parameters: the Markov chain approach, J Appl Stat 28 (2001), 875–885] Furthermore, we assume that the length of time that the process remains in control is exponentially distributed which allows us to apply the Markov chain approach for developing the cost model. We apply a genetic algorithm to determine the optimal values of model parameters by minimizing the cost function. A numerical example is provided to illustrate the performance of the proposed models and to compare the cost of the pure economic and ESD for three-level control charts. A sensitivity analysis is also conducted in this numerical example.     

A Hellinger distance approach to MCMC diagnostics

Bayesian analysis often requires the researcher to employ Markov Chain Monte Carlo (MCMC) techniques to draw samples from a posterior distribution which in turn is used to make inferences. Currently, several approaches to determine convergence of the chain as well as sensitivities of the resulting inferences have been developed. This work develops a Hellinger distance approach to MCMC diagnostics. An approximation to the Hellinger distance between two distributions f and g based on sampling is introduced. This approximation is studied via simulation to determine the accuracy. A criterion for using this Hellinger distance for determining chain convergence is proposed as well as a criterion for sensitivity studies. These criteria are illustrated using a dataset concerning the Anguilla australis, an eel native to New Zealand.