Oligopoly and Merger: A Simple Classroom Game

Professor Miller describes a game which has been used in intermediate price theory courses as well as in introductory classes. Two versions are presented—a duopoly and a six-firm market, both with undifferentiated product and a known market demand schedule. Students are also asked to make a monopoly of the six firms by forming a trust or holding company. Miller contends that the game is more stimulating than lectures aud suspects that it will result in longer retention.     

Material Offshoring: Alternate Measures

Industry measures of offshoring of material inputs are often generated using the proportionality assumption applied to aggregate import data—that the import share of each commodity used in the production process for a particular industry is similar to the import share of a commodity for the total economy. This note compares estimates of offshoring for the Canadian manufacturing sector derived using this assumption to four alternatives: two measures that use direct measures of firm‐based imports, and two hybrid measures that use both input and import information. These indirect measures are compared to survey estimates that directly assess import intensity in the production process in an effort to evaluate which indirect method yields more reasonable offshoring measures.     

基于星载极化SAR数据的农作物分类识别进展评述

［目的］农作物播种面积信息不仅可为农情监测和作物估产提供重要的数据保障,还是国家制定粮食政策和经济计划的重要依据。快速、准确地获取农作物播种面积信息能为农业生产管理提供决策支持。极化SAR不受云雨天气的影响,在农作物遥感监测方面具有巨大的应用潜力,有效利用极化SAR数据进行农作物识别研究对促进雷达技术在国家农业遥感监测和农业供给侧结构性改革中发挥更大作用具有重要意义。［方法］以星载极化SAR技术的发展过程为论述主线,从单、双极化SAR数据,单、双极化SAR数据结合光学影像,全极化SAR数据三个发展阶段,对极化SAR数据在农作物分类识别中的研究与应用进行总结,并对比分析不同的识别特征、融合算法以及分类算法的优缺点。［结果］以往研究存在以下不足：当前研究多以识别水稻为主,对于难以识别的旱地作物研究较少;目前对旱地作物识别精度不高,平均识别精度不足85%;缺乏对不同作物散射机制及其随时相变化的研究,导致分类算法机理性不足,普适性较差。［结论］在今后的研究中,旱地作物散射机制的定量确定,如何利用散射机制及其变化来提高旱地作物遥感识别精度和普适性;目前分类算法大都是基于光学影像设计,如何利用SAR特殊的成像方式优化设计适用于极化SAR数据的分类算法,得到更高的分类精度;如何更好的跟光学遥感等多源数据（光学数据、GIS数据等）结合来提高精度,将成为未来极化SAR农作物识别中三个亟需重点解决的问题。     

A Jump-diffusion Model for Exchange Rates in a Target Zone

We propose a simple jump-diffusion model for an exchange rate target zone. The model captures most stylized facts from the existing target zone models while remaining analytically tractable. The model is based on a modified two-limit version of the C OX , I NGERSOLL and R OSS (1985) model. In the model the exchange rate is kept within the band because the variance decreases as the exchange rate approaches the upper or lower limits of the band. We also consider an extension of the model with parity adjustments, which are modeled as Poisson jumps. Estimation of the model is by GMM based on conditional moments. We derive prices of currency options in our model, assuming that realignment jump risk is idiosyncratic. Throughout, we apply the theory to EMS exchange rate data. We show that, after the EMS crisis of 1993, currencies remain in an implicit target zone which is narrower than the officially announced target zones.     

民营化进程、企业目标函数选择与转轨效率

文章把转轨过程看作是政府可控的变量,从我国转轨中民营企业独特的目标函数出发,分析经济转轨过程中国有企业的成本函数选择对民营企业经营目标和经营行为的影响,以及在改革进程可控条件下,不同程度的改革进程是如何决定民营企业对目标函数和企业行为选择的,并对该选择与改革对社会福利水平的影响作了进一步分析。研究发现,政府与民营企业具有追求收入最大化内在合作的要求,该要求是竞争中双方博弈的均衡解;在非利润最大化目标函数的框架下,选择渐进转轨不会导致社会总产出的急剧下降,从而避免经济转型发生社会震荡。并且民营企业在改革进程中的目标函数选择与企业行为与实施的改革战略(改善社会福利)具有内在的一致性,因此,民营企业在改革不同阶段的选择行为对改革进程起到了一定的促进作用。     

Effectiveness of harvest strategies in achieving multiple management objectives in a multispecies fishery

Fisheries management is characterised by multiple objectives, some of which may be complementary, while others may require trade‐offs between outcomes. Balancing these objectives is made more complex in the case of multispecies and multigear fisheries. In this paper, we develop a bioeconomic model that captures the key elements of such a fishery to test a range of potential harvest strategies to provide insights into how economic target reference points could lead to both desirable and undesirable management outcomes (e.g. discards). The model is developed as a long‐run optimisation model to identify target reference points to achieve multispecies maximum economic yield, and a dynamic recursive optimisation model, which includes more realistic representation of fishers’ behaviour, such as discards and trading of under‐caught species quotas. The potential economic, social and ecological impacts are evaluated using data envelopment analysis (DEA). The results suggest that the use of proxy target reference points can result in short‐term economic benefits at the cost of slower stock recovery and higher discarding. Limiting the number of species subject to quota controls may also prove beneficial in multispecies fisheries, while ensuring quota markets are efficient is likely to produce benefits irrespective of the harvest strategy adopted.     

激电中梯和激电测深在寻找铜锌多金属矿中的应用

目前在多金属矿床勘查的物探方法中,激电中梯和激电测深是一种最有效的物探方法之一,在分析勘查区的地质资料的基础之上,合理布设测线,合理选取电极装置,通过分析整理激发极化法电测深数据,得到能够较准确地反映地下矿体的赋存、分布等特征的地质成果资料,预测成矿有利区段,所圈定锌多金属矿找矿靶区在后来的地质找矿工作中得到了证实。     

基于人工免疫算法的多无人机分布式任务分配方法

对多无人机任务分配问题进行了研究,在重量和路径负载均衡的基础上建立了带有攻击顺序的01决策变量的模型,运用分布式的人工免疫算法对该模型进行仿真实验,最终得到每个无人机攻击的目标顺序以及目标函数值,实验证明该方法在得到不劣于遗传算法结果的同时,提高了寻找最优解的收敛速度。     

AHP在第三方物流服务商选择中的应用

第三方物流供应商的选择是企业物流外包中的一个关键问题,有效地评价方法是正确选择第三方物流服务供应商的前提。我们应该采用合理、有效地评价方法对其进行综合评价,才能保证选择结果的科学性。文章运用AHP确定第三方物流服务商评价指标权重,并通过定量与定性相结合的方法对第三方物流服务商进行评价,使企业对第三方物流服务商的选择更为科学、合理。     

一起110kV电缆中间接头故障分析

通过对发生故障的110 kV电缆中间接头进行解剖,分析推断故障原因可能是绝缘层与半导电屏蔽层间存在微小气隙缺陷,经长期运行发生局部放电并发展成贯穿性导电通道造成绝缘击穿,提出采取在线局部放电测试的方法对设备健康状态进行监控,及时发现缺陷并予以消缺,防止故障发生.