The role of credit officers in the performance of micro loans

This paper proposes a structural model explicitly considering the role played by credit officers in loan performance. The credit officer's ability is decomposed into the screening and the audit stage. This model is estimated using a rich database from VivaCred – a Brazilian NGO. Results suggest that: (i) there is substantial heterogeneity among credit officers in the sample; (ii) their ability affects more the screening than the audit stage; and (iii) their estimated ability is correlated with their experience at VivaCred but not with their experience before joining the organization. Evidence suggests that a reduction in staff turnover would be beneficial to the institution.     

柔性延迟申领养老金政策视角下个人账户效益分析

文章以柔性退休延迟申领养老金政策为研究对象,从职工个人的缴费积累和养老金待遇领取两个角度对上海市柔性延迟申领养老金政策的个人账户效益进行测算评价.通过对柔性延迟申领养老金五种方案下的缴费、收益测算分析,得出如下结论:劳动者延迟申领养老金有利于个人账户的积累;延迟申领养老金有利于劳动者退休后养老金水平的提高;柔性延迟申领养老金政策通过养老金权益的调整可以起到对劳动者的激励作用.     

Optimal inter-area coordination of train rescheduling decisions

Railway dispatchers reschedule trains in real-time in order to limit the propagation of disturbances and to regulate traffic in their respective dispatching areas by minimizing the deviation from the off-line timetable. However, the decisions taken in one area may influence the quality and even the feasibility of train schedules in the other areas. Regional control centers coordinate the dispatchers’ work for multiple areas in order to regulate traffic at the global level and to avoid situations of global infeasibility. Differently from the dispatcher problem, the coordination activity of regional control centers is still underinvestigated, even if this activity is a key factor for effective traffic management.This paper studies the problem of coordinating several dispatchers with the objective of driving their behavior towards globally optimal solutions. With our model, a coordinator may impose constraints at the border of each dispatching area. Each dispatcher must then schedule trains in its area by producing a locally feasible solution compliant with the border constraints imposed by the coordinator. The problem faced by the coordinator is therefore a bilevel programming problem in which the variables controlled by the coordinator are the border constraints. We demonstrate that the coordinator problem can be solved to optimality with a branch and bound procedure. The coordination algorithm has been tested on a large real railway network in the Netherlands with busy traffic conditions. Our experimental results show that a proven optimal solution is frequently found for various network divisions within computation times compatible with real-time operations.     

The use of limited dependent variable techniques in strategy research: issues and methods

Strategy researchers are increasingly turning their attention from examining the impact of strategic choices on firm performance to examining the factors that determine strategic choices at the firm level. This shift of research orientation has meant that researchers are increasingly faced with a limited dependent variable (LDV) that takes a limited number of usually discrete values, for which LDV methods such as logit or probit are required. Despite their growing popularity, there appears to be widespread problems in the use of LDV methods. This research note complements recent studies that offer general guidelines by presenting and illustrating the practical steps needed to implement the methods essential for analyzing and interpreting the results from LDV models. Copyright © 2009 John Wiley & Sons, Ltd.     

Reference Dependent Preference and Labor Supply: Evidence from China

This paper investigates the daily labor supply decisions of Hangzhou cabdrivers. We find that Hangzhou cabdrivers’ wage elasticity is significantly positive, their working decisions are largely affected by shift time, and crude proxy variables for income; hours targets can hardly explain their working behavior. Nevertheless, Hangzhou cabdrivers are still affected by reference dependent preference. Using new empirical strategies, we show that cabdrivers are more likely to continue working when wage rates are unexpectedly low and more likely to quit when wage rates are unexpectedly high.     

一种基于传播时延修正的网络时间互同步算法

介绍了一种时间互同步算法的基本原理,并通过仿真试验分析了该算法在不同环境下的性能,指出其应用在地理覆盖范围较大的网络中的局限性。为改善该算法在实际应用场景中的性能,提出了一种基于传播时延修正的新策略。仿真结果表明,改进后的时间同步算法在传播时延不能忽略的场景中的性能远远优于原来的算法,其同步精度由原算法的1 ms左右提高到几微秒到几十微秒的量级,在实际工程中具有较高的应用价值。     

中外黄金市场混沌特性比较——基于相空间重构技术

运用相空间重构技术,分别对上海黄金交易所和伦敦黄金交易市场的现货黄金价格时间序列进行相空间重构,运用互信息法计算嵌入延迟,运用Cao方法计算嵌入维数,运用小数据量法计算最大Lya-punov指数,运用G-P算法估算关联维数和Kolmogorov熵,得出上海黄金市场具有混沌和分形特征的结论。进而对两系统的混沌特性、有效价格预测时间尺度等进行比较,发现两市场整体的混沌程度相当,其中上海黄金市场的复杂度小于伦敦黄金市场,但其价格波动的发散性更强、最大可预测时间更短。最后指出,形成此差异的原因可能是上海黄金交易所是一个次要市场,其价格形成机制不同于作为主要市场的伦敦黄金市场。     

加性白噪声下基带延迟锁定环跟踪精度的计算

研究了加性白噪声下基带延迟锁定环跟踪精度的计算问题,着重讨论了积分时间和 环路带宽的关系。以码延迟相关鉴别器的等效鉴相模型为基础,研究了相关器输出噪声特性 及其在输入端等效噪声的特性,推导了线性跟踪环输出噪声方差的计算公式,并得到了积分 时间和环路带宽分别起主导作用时的简化计算公式,使两种不同的结论得到了统一。     

Price formation in the German biodiesel supply chain: a Markov‐switching vector error‐correction modeling approach

Changing linkages between agricultural and energy markets have attracted considerable attention in research and policy discussions during recent years. As one of the largest biofuel markets worldwide, the German biodiesel market is of particular interest. It has grown rapidly since the beginning of the new millennium, with this growth being driven mainly by political interventions. Vertical price transmission channels along the biodiesel supply chain are analyzed in this study. We examine the relationship between diesel and biodiesel prices, and between rapeseed oil, soy oil, and biodiesel prices between 2002 and 2008. Due to pronounced changes in market conditions and the policy framework, a regime‐dependent Markov‐switching vector error‐correction model is used. The regimes are characterized by markedly different price adjustment behaviors. Before 2005 and from late 2007 onward, a regime characterized by the strong orientation of biodiesel prices toward diesel prices dominates. Between 2005 and 2007, biodiesel and rapeseed oil prices are mutually interdependent. Frequent switches between the regimes of the price dynamics during this period indicate a high extent of uncertainty and instability in the market.     

基于局域网的实时语音通信时延研究

在局域网中语音通信时延是影响语音质量的重要因素。为了最大限度地降低局域网中语音通信时延,提高语音质量,以采用低阶音频函数和UDP协议实现语音传输系统为基础,通过实验并分析了造成局域网中语音通信时延的主要因素,提出了在局域网中最大限度地降低实时语音通信时延的解决策略,实验数据证明,时延的分析是正确的,降低时延的策略是有效的。