IPD军工科研企业研发体系建设研究

在激烈的市场竞争下，军工科研企业面临如何有效地降低研发成本、提高研发效率、提升研发质量，从而实现规模化、产业化发展等问题。集成产品研发（Integrated Product Development, IPD）由IBM首先成功实践，可以帮助企业快速、低成本、准确地开发出满足市场的产品，快速从以项目为核心、解决产品有无问题的阶段，向以平台和共享为核心的产业化发展阶段跨越。从军工企业科研面临的问题，研究了IPD军工科研企业如何借鉴IPD思想，本地化建立符合军工业务特点的研发体系，提出了基于IPD的研发体系建设目标、建设内容和实施步骤。     

单车场无时间窗甩挂运输车辆调度的启发式算法

考虑了牵引车空驶、带空挂车行驶和带重挂车行驶所引起的成本差异，定义了牵引车运行成本的概念，将总运行成本最小作为调度方案优劣的判别指标，并同时考虑牵引车数量最少。将牵引任务分为四种类型，定义了任务链、虚拟任务、链内交叉和链间交叉的概念，提出了一种求解该类单车场甩挂运输车辆调度无时间窗约束的启发式算法，包括初始调运方案、链内优化、空车调运交叉、牵引车数量优化和链间交叉。最后给出了仿真算例，算法优化后的最终方案与初始方案相比，牵引车数量减少，总运行成本降低，验证了算法的有效性和可行性。     

On estimating long-run effects in models with lagged dependent variables

A common procedure in economics is to estimate long-run effects from models with lagged dependent variables. For example, macro panel studies frequently are concerned with estimating the long-run impacts of fiscal policy, international aid, or foreign investment.Our analysis points out the hazards of this practice. We use Monte Carlo experiments to demonstrate that estimating long-run impacts from dynamic models produces unreliable results.Biases can be substantial, sample ranges very wide, and hypothesis tests can be rendered useless in realistic data environments. There are three reasons for this poor performance. First, OLS estimates of the coefficient of a lagged dependent variable are downwardly biased in finite samples. Second, small biases in the estimate of the lagged, dependent variable coefficient are magnified in the calculation of long-run effects. And third, and perhaps most importantly, the statistical distribution associated with estimates of the LRP is complicated, heavy-tailed, and difficult to use for hypothesis testing. While many of the underlying problems have been long-known in the literature, the continued widespread use of the associated empirical procedures suggests that researchers are unaware of the extent and severity of the estimation problems. This study aims to illustrate their practical importance for applied research.     

A decision method for supplier selection in multi-service outsourcing

Although supplier selection in multi-service outsourcing is a very important decision problem, research concerning this issue is still relatively scarce. This paper proposes a decision method for selecting a pool of suppliers for the provision of different service process/product elements. It pioneers the use of collaborative utility between partner firms for supplier selection. A multi-objective model is built to select desired suppliers. This model is proved to be NP-hard, so we develop a multi-objective algorithm based on Tabu search for solving it. We then use an example to show the applicability of the proposed model and algorithm. Extensive computational experiments are also conducted to further test the performance of the proposed algorithm.     

Policy‐related implementational fluidity in subsistence marketplaces

This paper sheds light on policy‐related implementational fluidity—a context‐dependent adaptation of policies—adopted by policy implementers to address heterogeneous needs of subsistence consumer‐merchants (SCMs). In subsistence research, despite the emphasis on bottom‐up policymaking, implementational fluidity persists because of institutional and sociocultural factors that hinder policy implementers’ from effectively and accurately implementing the policies. To enrich the current bottom‐up policy process, this paper shares insights from an ethnographic study of Fijian market traders and marketplace personnel (policy implementers) and shares insights on how implementational fluidity manifests in subsistence marketplaces. Analysis reveals the interplay amongst sociohistorical context, marketplace relational dynamics and policies leading to policy adjustments and re‐negotiation by marketplace personnel and perceived injustices amongst the SCMs. The paper provides policy recommendations and practice ideas for subsistence researchers and policy practitioners to examine policy implementation gaps and the role of policy implementers in subsistence marketplaces.     

学者型CEO更加自律吗?——学术经历对高管在职消费的影响

本文选取2010—2016年中国沪深A股上市公司样本,实证检验CEO学术经历对高管在职消费行为的影响。研究发现,学术经历有助于CEO强化道德自觉、增强道德自律,形成内在的自我约束与监督机制,进而抑制了其所在企业的高管在职消费活动。当CEO拥有高层次学术经历或来自内部晋升时,CEO学术经历对高管在职消费的抑制效应更为显著。该结论在采用双重差分模型、Heckman两阶段模型控制潜在的内生性问题及其他稳健性检验之后仍然成立。进一步研究表明,在自由现金流较多、董事会规模较大或独立性较低、外部审计监督较弱以及产品市场竞争程度较低等公司内外部治理环境较差的情景下,学者型CEO的自律品质所能发挥的治理作用更大,对高管在职消费的抑制效应也更为明显。此外,在党的十八大之后,随着“八项规定”等多项高压反腐政策的出台,政策效应在国有企业高管在职消费的治理中发挥着主导性作用,CEO学术经历对国有企业高管在职消费的抑制效应有所下降。本文为高管学术经历的治理效应假说提供了证据支持,对于上市公司规范和治理高管在职消费行为、选聘合适的高管人才具有重要的借鉴意义。     

Post encroachment time threshold identification for right-turn related crashes at unsignalized intersections on intercity highways under mixed traffic

Abstract

Unsignalized intersections in developing countries experience many serious conflicts between cross-traffic due to indiscipline traffic manoeuvrability. Historically, Post Encroachment Time (PET) has gained attention as a proximal indicator to analyze crossing conflicts. However, identifying an appropriate PET threshold to classify critical conflicts for highly heterogeneous traffic scenario is still an unexplored area. Consequently, this study proposes a novel approach of PET threshold identification with proof of application by collecting data from ten intersections located on four-lane intercity highways in the National Capital Region (NCR), India. Both crossing conflicts and right-turn related crash data (for the left-hand drive) are collected. Their correlations are thoroughly studied for each PET threshold using a quantitative technique considering all and individual vehicle categories. Finally, a qualitative analysis is done by ranking the sites based on cumulative PET and related crashes to verify the proposed quantitative technique. A PET threshold of 1?s is obtained from both the techniques which can be used to identify critical conflicts for unsignalized intersections located on four-lane intercity highways. The proposed methodology will serve as an alternative, faster and effective tool to evaluate the hazardousness of unsignalized intersections located on intercity highways under highly heterogeneous traffic condition.     

Lumpy Investment and Corporate Tax Policy

In the presence of both convex and nonconvex capital adjustment costs in a dynamic general equilibrium model, corporate tax policy generates both intensive and extensive margin effects via the channel of marginal Q. Its impact is determined largely by the strength of the extensive margin effect, which, in turn, depends on the cross‐sectional distribution of firms. Depending on the initial distribution of firms, the economy displays asymmetric responses to tax changes. Moreover, an anticipated increase in the future investment tax credit reduces investment and adjustment rate initially.     

Minimising emergency response time of ambulances through pre-positioning in Dhaka city,Bangladesh

This study conducted a large-scale survey in Dhaka, Bangladesh; the survey involved 95 major hospitals, more than 3000 emergency room patients, and 2 of the largest ambulance operators. Currently, most ambulances are parked within the vicinity of hospitals and are either dispatched or fetched by the acquaintances of the patient on demand, resulting in lengthy round trips. Reducing the response time of ambulances would certainly improve the emergency service, and pre-positioning of the ambulances could be a solution to reducing the response time. This study used two approaches to address the problem. First, the location-allocation problem was solved to find the optimal number of ambulance locations by maximising the demand coverage. Second, separate location-allocation for the peak and off-peaks, using K-means clustering, was applied to systematically optimise the ambulance positioning in small clusters near demand points. These approaches could substantially improve the existing emergency response time. Distributing ambulances near demand points yielded greater improvements in response time than when the ambulances are stationed near hospitals.