Flexible Backup Supply and the Management of Lead‐Time Uncertainty

We consider replenishment decisions for a constant rate demand environment from a supplier with uncertain lead times. We study the potential use of a flexible backup supplier as an emergency response to accurate lead‐time information arriving at (or close after) the beginning of the demand interval and well after an original order with the stochastic lead‐time supplier has been placed. The emergency response decisions involve whether to order and how much from the flexible backup supplier, with the objective of minimizing the cost of meeting demand. We derive the optimal emergency‐response policy and clearly outline its implications on the optimized safety lead time of the original order placement and on the cost of meeting demand. We examine the impact on the use of the flexible backup supplier of factors like the arrival time of accurate lead‐time information and the response lead time of the backup supplier. We further study the potential benefits of the use of the flexible backup supplier in a dual role: as one of the two suppliers in a redundant supply system assigned to originally meet the demand and as an emergency response to later‐arriving lead‐time information. Our numerical studies illustrate the benefits from the use of the flexible backup supplier as an emergency response, but for reasonable purchase premiums and short lead times of flexible backup supply options, their use in a dual (regular and emergency response) role often leads to improved performance over safety lead‐time single and uncertain lead‐time supplier‐replenishment strategies. The benefits of the backup supply options are accentuated the higher the lead‐time uncertainty of the stochastic lead‐time supplier is.     

国债市场利率期限结构波动的对偶变换建模

本文针对传统利率期限结构拟合曲线存在过度波动问题,构建定价误差绝对距离和波动曲率双重最优化模型,借助对偶几何程序转换为在线性约束区域内的绝对距离最小化问题,并运用负指数平滑立方L1样条和计算几何逼近算法求解模型参数,通过负指数立方L1样条、NSS模型和B样条进行样本内拟合与样本外预测能力的比较,证实负指数立方L1平滑样条对利率期限结构波动的定价精确度、结构性拟合和样本外预测能力均有明显的优势,丰富了国债市场利率期限结构波动与定价的理论基础和研究方法。     

Bootstrap estimation and model selection for multivariate normal mixtures using parallel computing with graphics processing units

In applications of multivariate finite mixture models, estimating the number of unknown components is often difficult. We propose a bootstrap information criterion, whereby we calculate the expected log-likelihood at maximum a posteriori estimates for model selection. Accurate estimation using the bootstrap requires a large number of bootstrap replicates. We accelerate this computation by employing parallel processing with graphics processing units (GPUs) on the Compute Unified Device Architecture (CUDA) platform. We conducted a runtime comparison of CUDA algorithms between implementation on the GPU and that on a CPU. The results showed significant performance gains in the proposed CUDA algorithms over multithread CPUs.     

Exploring rigour in autoethnographic research

Abstract

The changing face of qualitative research has opened up discourses on the validity and rigour of research processes and products. A current debate is whether the criteria traditionally used to judge the rigour of quantitative research are appropriate to assess the academic integrity of qualitative research including autoethnography. The purpose of this article is to appraise views on the academic rigour, validity and scientific accountability of research in general and autoethnographic research in particular. The researcher reports on issues of rigour in conducting autoethnographic research from her own experience and that of published autoethnographic researchers. The issue of relevant appraisal criteria against which the research integrity and rigour of autoethnographic studies can be assessed is investigated. It is concluded that the academic rigour of autoethnographic studies should be established to enhance its credibility and value and that the criteria used need to be judiciously determined and applied.     

How old is old? Revising the definition based on life table criteria

Sixty‐five has long been thought of as the point of entry into “old age.”; We propose a number of life table criteria for answering the following questions: If 65 was considered appropriate four decades ago, what is the corresponding age today? If 65 was (implicitly) a male‐oriented definition four decades ago, as we believe it was, what would have been the appropriate definition for women at that time, and what is it today? We address these questions by applying our criteria to Canada, using 1951 and 1991 life tables, but the criteria could be applied equally well to other countries. For other developed countries we would expect broadly similar results.     

Extreme ranking analysis in robust ordinal regression

We extend the principle of robust ordinal regression with an analysis of extreme ranking results. In our proposal, we consider the whole set of instances of a preference model that is compatible with preference information provided by the DM. We refer to both, the well-known UTA^GMS method, which builds the set of general additive value functions compatible with DM's preferences, and newly introduced in this paper PROMETHEE^GKS, which constructs the set of compatible outranking models via robust ordinal regression. Then, we consider all complete rankings that follow the use of the compatible preference models, and we determine the best and the worst attained ranks for each alternative. In this way, we are able to assess its position in an overall ranking, and not only in terms of pairwise comparisons, as it is the case in original robust ordinal regression methods. Additionally, we analyze the ranges of possible comprehensive scores (values or net outranking flows). We also discuss extensions of the presented approach on other multiple criteria problems than ranking. Finally, we show how the presented methodology can be applied in practical decision support, reporting results of three illustrative studies.     

Strategic Sourcing in the Presence of Uncertain Supply and Retail Competition

This study develops an analytical model to evaluate competing retail firms' sourcing strategies in the presence of supply uncertainty. We consider a common supplier that sells its uncertain supply to two downstream retail firms engaging in price competition in a horizontally differentiated product market. The focal firm has a dual‐sourcing option, while the rival firm can only source from the common supplier. We assess the system‐wide effects of supply uncertainty on the focal firm's incentive to pursue the dual‐sourcing strategy. We find that the focal firm's dual‐sourcing strategy can create a win–win situation that leads to increased retail prices and expected profits for both firms. Furthermore, under certain conditions, we show that it is beneficial for the focal firm to strategically source from the common supplier, even if its alternative supplier offers a lower wholesale price. Overall, we identify two types of incentives for adopting the dual‐sourcing strategy: the incentive of mitigating supply risk through supplier diversification and the incentive of strategic sourcing for more effective retail competition.     

论风险刑法理论的正当性根据

大规模的工业技术生产方式的运用,正深刻地改变着我们所生存的社会,现代社会正步入如德国学者贝克所言说的＂风险社会＂。就刑法而言,在风险社会背景下,刑法的疆域已经扩展到风险规制的领域,从而＂风险刑法＂理论应运而生。在风险刑法理论的正当性根据的探讨上,从刑事本体性、刑事现实性和刑事政策性三个维度寻求了风险刑法理论的正当性根据,从而期待风险刑法理论得到更多刑法同仁的认同。     

基于内容分析法的电子商务模式分类研究

随着全球电子商务的蓬勃发展,商务模式作为描述企业如何创造价值的概念成为一个热门研究领域。然而,在电子商务模式分类这一基本问题上还未形成共识,人们依据不同分类标准建立了不同的电子商务模式分类框架。本研究对CNKI中文期刊全文数据库中篇名或摘要包含电子商务模式的文献中的商务模式分类标准及类别进行内容分析,结果表明出现频次较高的分类标准依次为交易主体、交互模式和价值链整合、价值链中的位置和盈利方式、市场主导力量和新旧经济5种,并且交互模式和价值链整合、新旧经济以及价值链中的位置和盈利方式这3种标准随时间推移所占比例逐渐上升,表明主流分类标准越来越关注于价值的创造方式和创造过程,这一趋势与电子商务模式定义所揭示的价值创造本质及其发展趋势是一致的。同时,分类体系的多样性也影响了人们对电子商务模式的理解和沟通,未来研究需要提出基于价值主张的更为通用和全面的分类体系来指导商务模式创新实践。