农村土地股份合作制的经济解释与分析

研究了我国农村土地股份合作制的经济效益,并对其形成因素进行比较静态分析。主要的结论是:土地股份合作制理论上能够提高要素配置效率和农业生产效率;而经济发展状况、产业结构配置、农民就业风险、农村社会保障制度以及土地级差收益的分配是导致该制度产生的主要原因。     

基于一类两级供应链的激励机制策略研究

本文利用博弈论和信息经济学理论和方法,深入研究了一类两级供应链在产品价格固定、需求是随机的情况下激励机制的设立,以及该激励机制对供应商和零售商收益产生的影响。研究结果表明,本文设计的激励机制对提高供应链整体运作效益的有效性,并用实际算例加以验证。     

Economic Lot Scheduling Problem with Returns

Motivated by a case study of a company that produces car parts, we study the multi‐product economic lot scheduling problem for a hybrid production line with manufacturing of new products and remanufacturing of returned products. For this economic lot scheduling problem with returns (ELSPR), we consider policies with a common cycle time for all products, and with one manufacturing lot and one remanufacturing lot for each product during a cycle. For a given cycle time, the problem is formulated as a mixed integer linear programming (MIP) problem, which provides the basis for an exact solution. The application of this model for one of the core products of the case study company indicates a 16% reduction in cost compared to the current lot scheduling policy.     

定期信用支付条件下的多阶段货价变动型存贮问题

本文研究了定期信用支付条件下的多阶段货价变动型存贮问题,得到了最优订购策略并设计了算法以说明模型的使用。     

随机需求条件下产品退货政策协调与优化

本文研究了随机需求条件下基于退货的单周期单一产品逆向供应链模型.首先,研究了集中决策条件下集成厂商的利润函数,并讨论了实现利润最大化的最优性条件及其最优订货量;其次,在分散决策条件下,分别研究了制造商和销售商的利润函数,并讨论了销售商的最优性条件及其最优订货量;最后,在集中决策和分散决策模型的基础上,重点研究了供应链的协调与优化,得出了实现供应链协调的基本条件和两者之间的利润分配机制.通过制定批发价格和退货价格来实现两者之间的增加利润的任意分配.     

The dynamics of returns to education in Uganda: National and subnational trends

We assess empirically the changes in returns to education at the subnational level in Uganda using the Uganda National Household Surveys for 2002–3 and 2005–6. Our results indicate that average returns to schooling tended to converge across regions in the last decade. The overall trend in convergence of returns to schooling took place at all levels of educational attainment and this behaviour in returns to education is mostly driven by the dynamics of returns to schooling in urban areas. We analyse subnational convergence in returns to education and unveil deviant dynamics in Northern Uganda. We discuss the potential challenges to inclusive economic growth in Uganda which are implied by our results.     

How Excessive Stage Time Reduction in NPD Negatively Impacts Market Value

We empirically investigate how time reductions in particular product development stages impact market value. Using longitudinal project data from 107 firms, we compare stage times prior to and following investments in new product development process changes. Our analysis reveals a predominance of focus on time reduction in the late stages of product development. We also find support for the existence of an inverted‐U relationship between market performance and time reductions for some of these stages: beta testing and technical implementation. Therefore, while time reductions can improve time to market, we observe a clear limit to the benefits associated with stage time reductions at particular stages. We also investigate the role of strategic contextual factors such as the extent to which a firm's patented innovations rely upon a variety, as opposed to a limited range, of diverse technology classes. The extent of this technology‐span impacts optimal stage time reductions. We perform an in‐depth post hoc analysis with a small set of firms to uncover how they should invest in stage time reduction given our empirical results. The post hoc analysis highlights that some firms are likely overinvesting in stage time reductions and destroying market value.     

Product Design Awards and The Market Value of The Firm

Product design has increasingly been recognized as an important source of competitive advantage. This study empirically estimates the impact of effective design on the market value of the firm. We use a firm's receipt of a product design award as a proxy for its design effectiveness. Based on data from 264 announcements of design awards given to commercialized products between 1998 and 2011, we find that award announcements are associated with statistically significant positive stock market reactions. Depending on the benchmark model used to estimate the stock market reaction, the market reaction over a two‐day period (the day of announcement and the preceding day) ranges from 0.95% to 1.02%. The market reaction is more positive for smaller firms and for firms whose award winning products are consumer goods. However, a firm's growth potential, industry competitiveness, and whether a firm is a first time or repeated award winner do not significantly affect the market reaction.     

Impact of secondary market on consumer return policies and supply chain coordination

In this paper, we develop a unified model to study the inventory management problem of a product and the coordination of the associated supply chain consisting of a single supplier and considerably many retailers in the presence of a secondary market. Specifically, consumer returns are allowed in the initial sales. Then, we introduce a secondary market to salvage the returns and the leftovers from the initial sales. In this secondary market, a discount price will be offered to the consumers but no returns are accepted. Moreover, between the primary and the secondary market, there is an internal market where retailers can trade among themselves so that they are able to adjust their inventory levels to prepare for the sales in the secondary market. We study the retailers' and the supply chain's inventory decision in this case and highlight the impact of the secondary market on the sales as well as on the supply chain coordination contracts. We conclude that the secondary market helps us to increase the total wholesale volume. Numerical examples show that the total sales profit is also increased. However, the secondary market aggravates the incentive conflict between the retailers and the supply chain on deciding the optimal inventory levels and hence requires the supplier to offer more generous buyback or sales rebate contracts for coordination of the supply chain. Finally, we extend our analysis to more general cases and also show that our results are robust to some of the modeling assumptions.     

Macroeconomic Implications of Agglomeration

Cities exist because of the productivity gains that arise from clustering production and workers, a process called agglomeration. How important is agglomeration for aggregate growth? This paper constructs a dynamic stochastic general equilibrium model of cities and uses it to estimate the effect of local agglomeration on aggregate growth. We combine aggregate time‐series and city‐level panel data to estimate the model's parameters via generalized method of moments. The estimates imply a statistically and economically significant impact of local agglomeration on the growth rate of per capita consumption, raising it by about 10%.