太阳风作用下航天器表面充电效应分析

针对太阳风等离子体中航天器的充电过程,基于欧洲航天局开发的航天器表面充电仿真软件,建立了航天器的数值计算模型,模拟了太阳风等离子体与航天器的相互作用,实现了不同表面材料时航天器表面电位以及尾迹结构的计算分析,给出了近日环境下航天器周围的空间电位结构以及等离子体密度分布情况。研究结果表明:表面材料的选择将影响空间势垒深度以及尾迹结构,表面充电至更低电位的表面材料具有较小尾迹区域;航天器向阳面电位分布主要由光电子以及二次电子主导,而背阳面的电位分布则主要受到尾迹效应的影响。以上结果对太阳风环境航天器探测和评估等相关工作以及工程研究具有一定的理论参考价值。     

The Impact of the Unemployment Rate on Attrition of First-Term Enlistees

This study examines the effects of home-state unemployment rates on attrition behavior of Navy enlistees for successive career windows during the first term of service: the first 6?months, the second 6?months, the second year, and the third year of service. The results indicate that attrition is negatively associated with changes in the local unemployment rate during the first three career windows covering two years of service. However, after two years of service, the estimated effect of the unemployment rate becomes insignificant for most groups of sailors. This is likely because sailors with the poorest job matches are sorted out early in the first term of service.     

双源连续波对引信的辐照效应研究

为研究复杂电磁环境对某引信的影响,从双源连续波入手,运用双源连续波对工作状态某引信辐照的实验方法进行实验.实验结果表明,在以引信工作频率为中心的150MHz频率范围内对加电引信进行双源连续波辐照实验可使引信发火,辐照结束后引信工作正常,实验的重复性较好.两连续波频率间隔不同,可使引信发火的场强组合数值大小不相同,实验中当两连续波远离引信工作频率且频差10MHz以上时,发火场强组合近似呈线性.最后对双源连续波对引信的辐照效应机理作了分析,两连续波频率间隔不同,引信发火机理不同.     

静电放电对微机接口电路干扰效应研究

为研究静电放电(ESD)对微机接口电路的干扰效应,设计了一种单片机系统串行数据传输电路试验模型。利用静电放电模拟器对自行设计的单片机系统进行了效应试验,并对测得的试验数据进行了分析,得出了这类典型串口通讯在静电放电环境下的一些规律。     

城镇化与农民增收的相关性分析

从理论上分析,城镇化与农民增收之间存在很强的正相关关系;而现实中,在政策措施不科学的情况下,城镇化为农民增收带来了很大的负面效应。因而必须采取必要措施消除负面影响,充分体现城镇化对农民增收的正相关效应。     

空间辐射环境中的辐射效应

天然空间辐射环境与辐射效应基本机制是空间飞行器抗辐射加固研究中的两个关键问题, 本文总结了天然空间辐射环境的总体性质, 并对辐射效应基本机制进行了简要的分析, 指出了目前空间飞行器抗辐射加固研究的重点。     

农村文化建设对农村社会稳定的双向效应

社会稳定是改革发展的重要前提,而保持农村稳定是全社会稳定的关键。维护农村社会稳定根本途径在于文化建设,但文化建设对农村社会稳定有双向效应。文化建设对农村社会稳定的正面效应有减贫效应、社会结构优化效应、社会控制效应、社会心理优化效应和社会化效应,而文化建设的受益不均衡效应、虚化效应、过度社会动员效应及其信息失稳效应等又不利于农村社会稳定。因此,要充分重视农村文化建设的积极作用,也要清醒认识其负面效应,并为维护农村社会稳定考虑扬正抑负的对策。     

电离层不规则体对P波段星载SAR成像的影响

电离层不规则体导致星载合成孔径雷达（SAR）信号产生幅度及相位闪烁,严重影响低波段星载SAR的图像分辨性能。推导了具有普遍性的幂律谱对应的双频双点互相关函数。基于此研究了电离层对星载P波段SAR分辨性能的影响及其规律。研究表明,电离层不规则体导致星载P波段SAR两维分辨率恶化,图像峰值增益损失严重。电离层不规则体强度,谱指数,外尺度等参数的增大都会导致星载SAR图像分辨率及峰值增益进一步下降。基于相位屏技术的数值仿真结果验证了本文研究。     

Assortment optimization with position effects under the nested logit model

We study the assortment optimization problem with position effects under the nested logit model, whose goal is to find the revenue-maximizing subset of products as well as their corresponding display positions. In this joint assortment-position optimization problem, the choices of products are affected by not only their qualities and prices but also the positions where they are displayed. Despite determining the assortment and their corresponding display positions sequentially, we propose to solve this problem in an integrated way to obtain the optimal solution. We formulate this problem as a nonlinear binary integer programming model and develop a dynamic programming based solution approach to obtain the optimal assortment-position assignments. We carry out extensive numerical experiments to evaluate the benefit of our integrated approach. The most important insight we discover is that it is not necessarily better to put the most attractive products in the best position. Moreover, we show that compared to the sequential approaches, our approach can improve revenue by 10.38% on average, which suggests that firms should take into consideration position effects when making assortment decisions. Finally, we discuss results related to two extensions of this problem, that is, the special case when positions are preassigned to nests, and the joint assortment-position-price optimization problem.     

Economic impact of the ministry of defence’s budget: methodological design and results for the Spanish economy

This article analyses the economic impact of the expenditure budget of the Spanish Ministry of Defence (MoD) and its Autonomous Agencies (AA), distinguishing direct, indirect and induced effects. The input–output methodology is used to find intersectoral effects on the rest of the economy. The article quantifies the economic impact in terms of production, gross value added (GVA), employed population, tax revenue, and also in terms of its contribution to the gross domestic product (GDP) of Spain in 2010. The results show that the activity of the MoD and AA generates 1.2% of the country’s GDP and 1.7% of total employment in that year.