Supply Performance in Multi‐Echelon Inventory Systems with Intermediate Product Demand: A Perspective on Allocation

In this article, we study the performance of multi‐echelon inventory systems with intermediate, external product demand in one or more upper echelons. This type of problem is of general interest in inventory theory and of particular importance in supply chain systems with both end‐product demand and spare parts (subassemblies) demand. The multi‐echelon inventory system considered here is a combination of assembly and serial stages with direct demand from more than one node. The aspect of multiple sources of demands leads to interesting inventory allocation problems. The demand and capacity at each node are considered stochastic in nature. A fixed supply and manufacturing lead time is used between the stages. We develop mathematical models for these multi‐echelon systems, which describe the inventory dynamics and allow simulation of the system. A simulation‐based inventory optimization approach is developed to search for the best base‐stock levels for these systems. The gradient estimation technique of perturbation analysis is used to derive sample‐path estimators. We consider four allocation schemes: lexicographic with priority to intermediate demand, lexiographic with priority to downstream demand, predetermined proportional allocation, and proportional allocation. Based on the numerical results we find that no single allocation policy is appropriate under all conditions. Depending on the combinations of variability and utilization we identify conditions under which use of certain allocation polices across the supply chain result in lower costs. Further, we determine how selection of an inappropriate allocation policy in the presence of scarce on‐hand inventory could result in downstream nodes facing acute shortages. Consequently we provide insight on why good allocation policies work well under differing sets of operating conditions.     

陕西省人口承载力与适度人口定量研究

文章分析了人口承载力模型和适度人口量化测算模型,对陕西省人口承载力与适度人口规模进行定量估计,探讨了陕西省人口与经济社会、资源环境协调发展的对策。     

公司内部控制权的配置状态、寻租主体及治理机制分析

文章深入分析了作为公司治理效率基础的内部控制权配置,不仅考虑到了股东的投票权及其顺延的控制权特征,还注意到了人力资本带来的控制权。在此基础上总体考察股东、董事会和经理层的控制权配置状态及权力主体之间的关系,然后依据董事会层面控制状态的不同,分类剖析不同控制权配置模式的寻租主体和重要的治理机制,以期对公司控制权配置状况与治理机制之间的关系做较深入的诠释,为我国公司控制权配置提供一些启示。     

The Efficacy of Neural Networks in Predicting Returns on Stock and Bond Indices*

This paper uses two recently developed tests to identify neglected nonlinearity in the relationship between excess returns on four asset classes and several economic and financial variables. Having found some evidence of possible nonlinearity, it was then investigated whether the predictive power of these variables could be enhanced by using neural network models instead of linear regression or GARCH models. Some evidence of nonlinearity in the relationships between the explanatory variables and large stocks and corporate bonds was found. It was also found that the GARCH models are conditionally efficient with respect to neural network models, but the neural network models outperform GARCH models if financial performance measures are used. In resonance with the results reported for the tests for neglected nonlinearity, it was found that the neural network forecasts are conditionally efficient with respect to linear regression models for large stocks and corporate bonds, whereas the evidence is not statistically significant for small stocks and intermediate-term government bonds. This difference persists even when financial performance measures for individual asset classes are used for comparison.     

Dementia and Guardianship: Challenges in Social Work Practice

Decision-making within the context of dementia can be an uncertain and problematic process. This study critically examined challenges in social work practice in instances where a legal alternative decision-maker through guardianship proceedings was perceived as necessary. Theoretical perspectives from social constructionism underpinned the research. Five qualitative case studies were investigated. A thematic network analysis showed that the situations were constantly evolving and different players participated by bringing their own perspectives. In this process alliances were formed that reflected underlying dynamics of power. Contested issues included varied understandings of dementia and capacity, and differing constructions of risk, protection, and responsibility. The implications for practice are discussed with social work being well placed to make an important contribution through its traditional roles of negotiation, interpretation, and mediation between those who have discursive rights and those who do not. Ethical reasoning as a basis for decision-making was also of significance.     

Planning Service Capacity When Demand Is Sensitive to Delay

This paper presents a model designed to help determine the number of clerks or servers in a retail queuing situation. The model demonstrates a realistic treatment of the effect of waiting time on customer demand and revenues by treating the average waiting time as a form of price. Thus, the demand rate and service level are interrelated. The number of servers is obtained by balancing the cost of additional servers against the revenues and profits arising from greater demand. An example is shown, using data obtained from a supermarket, to demonstrate the insight gained from applying the model. Some extensions and research possibilities are considered, including a treatment of ancillary activities. An appendix examines a continuous version of the model which provides additional insight into the character of the model.     

HEURISTIC ALGORITHMS FOR CAPITAL-BUDGETING DECISIONS IN MULTIDIVISION FIRMS

This paper presents two versions of a heuristic algorithm to solve a model of the capital-budgeting problem in a decentralized multidivision firm involving no more than two exchanges of information between headquarters and divisions. Headquarters makes an allocation of funds to each division based upon its cash demand and its potential growth rate. Each division determines which projects to accept. Then, an additional iteration is performed to define the solution. More than one thousand examples were simulated resulting in an average relative error of less than one percent.     

农地经营权配置对农户收入影响的实证分析

农地流转是促进农地集中和规模化经营的重要手段,而明确农地经营权配置的集中程度对农户收入的影响,对于完善农地流转政策具有重要意义.运用2006年中国社会综合调查数据,利用基尼系数测算了农地经营权配置的集中程度,实证分析了农地经营权的集中程度对农户收入的影响,OLS回归分析发现,农地经营权的集中有利于农户收入水平的提高;分位数回归结果显示,农地经营权的集中更加有利于高收入农户,明显地提高了高收入农户的收入水平,而不利于低收入农户.因此,应当保证农地自由流转,促进农地经营权集中,提高大部分农户的收入水平;同时,对于不具有比较优势的低收入农户,应当制定相应的扶持政策和社会保障措施,保障其生活水平.