飞行器部件低散射载体的分析与设计

降低弱散射源的雷达散射截面,增强飞行器部件的隐身性能至关重要。但部件脱离飞行器后,需依托载体才能得到准确的隐身性能。通过探究低散射载体设计机理和思路,考虑爬行波、行波、入射频率等影响因素,设计了一款低散射载体。通过理论建模、特征基函数法仿真计算和试验测试方法验证,所设计的低散射载体的雷达散射截面足够低,可有效消除弱散射源以外的其他杂波散射影响,还原部件真实状态,有利于提升弱散射源隐身性能评估的准确性,从而优化飞行器隐身设计。     

Export Intensity and Plant Characteristics: What Can We Learn from Quantile Regression?

Using quantile regression and a rich cross section data set for German manufacturing plants this paper documents that the impact of plant characteristics on export activities varies along the conditional size distribution of the export/sales ratio. For example, firm size is statistically significant at a conventional level for the 0.25 quantile only; branch plant status matters at the upper tail of the conditional distribution of the export/sales ratio only; the craft shop dummy is only significant for the very top quantile; and patents do not matter at the very lower end of the conditional distribution of export over sales. This has implications both for understanding what makes a successful exporter, and for the design of policy measures with a focus on supporting exporters. JEL no. F10, D21, L60     

Are 18 Holes Enough for Tiger Woods?

This article addresses the selection problem in promotion tournaments. I consider a situation with heterogeneous employees and ask whether an employer might be interested in repeating a promotion tournament. On the one hand, this yields a reduction in uncertainty over the employees’ abilities. On the other hand, there are costs if a workplace stays vacant.     

Fiscal policy,wealth divergence,and lifetime utility

Using a two-country dynamic optimization model where the less patient country decumulates and the more patient one accumulates wealth, we analyze spillover effects of lump-sum and consumption taxes. A lump-sum tax on a country definitely harms the other country through a change in the rate of interest. A lump-sum tax on either country always improves the less patient country's asset position. A consumption tax has no spillover effect, although it is Pareto-inferior. Applying these results into a closed-country context with heterogeneous agents, we also discuss policy implications of a discriminatory tax.     

E-2C"鹰眼"预警机的现状与发展

本文简要论述了E-2C“鹰眼”预警机的作用及改进,重点介绍了E-2T“鹰眼”预警机和E-2C“鹰眼”2000预警机的特点及其作用,最后展望了E-2C“鹰眼”预警机的未来发展。     

基于中国经验重构新新贸易理论的分析框架

异质性企业贸易模型是新新贸易理论的基本分析框架,该模型从企业生产率异质性角度分析企业出口的决定因素,得到企业拥有高生产率是保证其出口的重要条件,从而出口企业的生产率要高于内销企业的结论。不过,对中国企业的经验研究却发现,出口企业的生产率未必高于内销企业,甚至低于内销企业,即中国出口企业存在"生产率悖论"。目前,对于"生产率悖论"的研究主要集中于经验分析,并没有提出一个合理解释该现象的理论模型。文章从扩展异质性企业贸易模型的角度,建立了一个旨在解释"生产率悖论"的数理模型。尽管该模型对"生产率悖论"具有解释作用,但是并没有否定生产率对企业出口的作用。文章进一步使用较新的LP方法计算了中国制造业企业的生产率并运用统计法检验了出口企业"生产率悖论"的存在性,检验结果表明中国制造业大部分行业不存在"生产率悖论"。总之,文章研究认为生产率只是企业出口的一个必要条件而不是充分条件,这也重新构建了新新贸易理论的分析框架。     

“前惯例”与企业惯例的形成机制研究

文章认为企业组织惯例形成之前都受到＂前惯例＂的影响,企业惯例的形成是一个在＂前惯例＂基础上自我扬弃的过程,这种惯例的综合与创造性运用能力是形成企业之间竞争力差异的根本原因。     

空中异构战术网络IP通信架构及协议开销分析

空中异构战术无线网络由多种不同类型的无线数据链网络构成,IP通信技术可有效解决空中平台异构无线网络的互联互通问题。给出了空中异构战术无线网络模型,并根据不同类型的无线数据链网络特点,分析了端到端通信协议栈关系以及不同无线数据链网络间协议转换与适配方式。探讨了网络静态和动态IP地址分配方法以及网络的路由架构与寻址方式,提出了不同无线数据链网络间IP报文传输的打包方式。对传输的开销性能仿真对比分析表明,基于通用成帧协议的打包方式的协议开销性能较优。     

一种基于地理信息系统的异构网络多目标算法

地理信息系统（Geographic Information System,GIS）和多目标算法为异构网络基站部署问题带来新的突破。ArcGIS系列是GIS专业化的管理软件,采用ArcGIS软件对包含学校、医院等场景的中国某市密集城区进行建模分析,并且提出基于目标权重因子的多目标离散粒子群算法（Multi-objective Discrete Particle Swarm Optimization algorithm based on Target Weight Factor,MDPSO/TWF）,基于多个目标函数整体最优研究异构网络基站部署问题。仿真结果表明,所提的MDPSO/TWF算法具有可行性和先进性,可以综合考虑网络负载和网络能效多个优化目标,将业务需求与实际基站选址相结合,在满足业务需求的基础上尽可能达到节能的目的。     

The Impact of Unionization Structures with Heterogeneous Firms and Rent‐Sharing Motives

How are unemployment and output affected if wages are set on the sector level rather than firm level? We take a new look at this question, allowing for heterogeneous firms and rent‐sharing motives. Without these motives, employment and output are lower under sector‐level wage‐setting due to higher wage markups. With rent‐sharing motives, however, firm selection is higher under sector‐level wage‐setting, which tends to increase employment and output, thus counteracting the markup effect. Simulations show that the firm‐selection effect decreases the difference between the two unionization structures substantially but it does not change the signs of the effects on output and employment.