中美贸易摩擦、全球价值链分工与福利效应

基于全球价值链分工,本文利用2018年中美贸易摩擦加征关税清单、世界投入产出数据库(WIOD)和中美家庭消费支出调查等数据,使用Taylor一阶展开法和考虑消费异质性的Creedy方法测算了中美贸易摩擦给全球价值链参与者带来的福利效应。研究发现:第一,无论基于Taylor一阶展开法还是Creedy方法,本轮贸易摩擦给中美两国自身带来的福利损失最大,且美国受损程度明显高于中国;第二,全球价值链上加拿大、墨西哥等北美自由贸易区(NAFTA)成员以及日本、德国、英国等经济体受中美贸易摩擦影响的福利损失较大;第三,国别责任分解表明中美福利损失主要来源于自身加税行为,而其他绝大多数经济体的损失主要由美国加税引致;第四,收入分配方面,中美贸易摩擦引致的中国福利损失是累退性的,而美国福利受损程度与收入呈现非线性的“倒U型”关系,表明中美贸易摩擦不利于收入分配格局的改善。全球价值链各参与者应秉持人类命运共同体理念,积极主动维护多边贸易规则和国际治理秩序。     

A Markov Chain Monte Carlo version of the genetic algorithm Differential Evolution: easy Bayesian computing for real parameter spaces

Differential Evolution (DE) is a simple genetic algorithm for numerical optimization in real parameter spaces. In a statistical context one would not just want the optimum but also its uncertainty. The uncertainty distribution can be obtained by a Bayesian analysis (after specifying prior and likelihood) using Markov Chain Monte Carlo (MCMC) simulation. This paper integrates the essential ideas of DE and MCMC, resulting in Differential Evolution Markov Chain (DE-MC). DE-MC is a population MCMC algorithm, in which multiple chains are run in parallel. DE-MC solves an important problem in MCMC, namely that of choosing an appropriate scale and orientation for the jumping distribution. In DE-MC the jumps are simply a fixed multiple of the differences of two random parameter vectors that are currently in the population. The selection process of DE-MC works via the usual Metropolis ratio which defines the probability with which a proposal is accepted. In tests with known uncertainty distributions, the efficiency of DE-MC with respect to random walk Metropolis with optimal multivariate Normal jumps ranged from 68% for small population sizes to 100% for large population sizes and even to 500% for the 97.5% point of a variable from a 50-dimensional Student distribution. Two Bayesian examples illustrate the potential of DE-MC in practice. DE-MC is shown to facilitate multidimensional updates in a multi-chain “Metropolis-within-Gibbs” sampling approach. The advantage of DE-MC over conventional MCMC are simplicity, speed of calculation and convergence, even for nearly collinear parameters and multimodal densities.     

数据挖掘中关联规则算法的考察

文章从算法角度对关联规则的提出、演变过程和前沿研究进行了较为详细的考察,并在此基础上提出了关联规则未来研究的领域和发展趋势。文章先详细地考察了关联规则的三类典型算法,然后总结了基于复杂数据属性的关联规则算法扩展。为考察其他方面的算法扩展和介绍其他学科领域对关联规则的研究奠定了基础。     

A quest for form: the tacit dimension of social work practice

This paper presents the findings of a small-scale study of social workers’ tacit understandings. Tacit is conceptualised as, difficult to describe knowledge, taken for granted knowledge or tacitly presupposed and silenced knowledge. The sample comprised 10 social workers employed in a statutory child protection context who participated in three stages of data collection. The research strategy encompassed six techniques: in-depth interviewing, observation, think-aloud, unstructured interviewing, reflective recall, and knowledge mapping. The tacit domain appears to be a rich site for practice understandings, as what practitioners explicitly offer is not a complete account of their knowing in practice. Interpretations suggest that practice may be guided by understandings of which practitioners are frequently unaware. When knowledge remains implicit, its content, level of influence, impact and use remain unconsidered as well. It is crucial, in attempting to gain clarity on any practice activity, that this realm be explored as it contributes to a fuller account of the realities of practice behaviour.     

数学教师学科教学知识建构初探

数学教育的专业化呼唤专业化的数学教师,教师知识结构成为教师专业发展的主题,学科教学知识是教师的知识结构的核心。专业数学教师仅有对教育的热爱和数学专业知识是不够的,本文分析了学科教学知识的地位、内涵及形成,提出了数学教师学科教学知识建构的重要性和可采取的措施。     

社会转型与基础教育走向

社会转型期,基础教育面临着巨大的冲击与挑战,其将如何改变传统的观念与作为,必然会对整个教育乃至经济,特别是对知识经济的发展起决定性作用.基础教育,一方面要适应经济的发展,成为经济发展的支撑,甚而引导经济良性发展;另一方面要有自己的尊严和特色,不应沦为经济发展的附庸.     

基于供应链管理的企业外包策略选择分析

外包是企业从传统纵向一体化管理模式向供应链管理模式转变的重要途径。然而,外包策略的有效选择对企业实际运作来说并非易事。该文从供应链管理的角度出发,通过对核心业务、顾客价值以及产品特性和业务类型的分析,探讨了在不同竞争环境中如何通过外包策略的选择来增强企业的竞争优势。     

Knowledge Life Cycle,Knowledge Inventory,and Knowledge Acquisition Strategies*

For a knowledge‐ and skill‐centric organization, the process of knowledge management encompasses three important and closely related elements: (i) task assignments, (ii) knowledge acquisition through training, and (iii) maintaining a proper level of knowledge inventory among the existing workforce. Trade‐off on choices between profit maximization in the short run and agility and flexibility in the long term is a vexing problem in knowledge management. In this study, we examine the effects of different training strategies on short‐term operational efficiency and long‐term workforce flexibility. We address our research objective by developing a computational model for task and training assignment in a dynamic knowledge environment consisting of multiple distinct knowledge dimensions. Overall, we find that organizational slack is an important variable in determining the effectiveness of training strategies. Training strategies focused on the most recent skills are found to be the preferred option in most of the considered scenarios. Interestingly, increased efficiencies in training can actually create preference conflict between employees and the firm. Our findings indicate that firms facing longer knowledge life cycles, higher slack in workforce capacity, and better training efficiencies actually face more difficult challenges in knowledge management.     

Supply Chain Conflict Due to Store Brands: The Value of Wholesale Price Commitment in a Retail Supply Chain*

Store brands are of increasing importance in retail supply chains, often causing channel conflict, as the retailer's product directly competes with the manufacturer's national brand. Extant research on the resulting channel interactions either assumes the national brand manufacturer can credibly commit to maintaining a wholesale price or that he lacks such ability. However, these two scenarios imply very different supply chain interactions, as only a national brand manufacturer with commitment ability can strategically adjust a national brand wholesale price to prevent a store brand introduction by the retailer. We specifically analyze the impact of this assumption on the manufacturer, the retailer, and the customers. We determine when long‐term contracts that provide the manufacturer with such commitment ability can improve supply chain profitability.