机载远程战场侦察雷达发展评述

主要说明顾固定冀和直升机载战场侦察雷达的特点，以及近年来机载战场侦察雷达的发展状况并展望今后的发展趋势。     

《电讯技术》专题资料《雷达探测技术》题要（一）

战场侦察直升机雷达系统的应用和发展（石星，喻光正，宋万忠，冯尚诚） 全文概述了战场侦察直升机系统的特点，介绍了目前典型的战场侦察监视系统及其应用，归纳了战场侦察监视直升机系统的主要技术，并对其发展趋势进行了总结。     

极有发展前任的三种新型战场侦察雷达

由于现代战争对侦察雷达提出了大范围、宽正面、全天候、反隐蔽（反隐身）、实时可靠地探测战场目标的要求，因此，侦察雷达已从传统地陆基型向升空型发展。在未来２１世纪的战争中，机载远程战场侦察雷达系统、机载穿透树丛侦察雷达和无人机载战场侦察雷达，将成为极有发展前途的情报侦察传感器。本文简要评述这三种新体制的侦察雷达。     

弹载雷达侦察干扰设备设计

论述了弹载雷达侦察干扰设备的天线设计、接收机设计和信号处 理硬件设计,并从实际需求出发,重点讨论了信号处理算法中的信号检测技术、瞬时测频技 术、雷达信号脉内调制识别技术和干扰信号产生技术。仿真结果表明所采用的信号处理算法 可行,对于弹载平台雷达侦察干扰设备的设计具有指导意义。     

机载战场侦察MTD雷达运动补偿技术评述

本文叙述战场侦察雷达装载于直升机平台上工作时，雷达杂波回波的特点。并对杂波抑制以及补偿平台运动影响的几种技术进行综述。     

2D机载雷达目标定位精度分析

对于2D机载雷达,由于缺乏准确的俯仰角信息,无法准确定位地面目标。针对该问题,给出了机载雷达目标定位的数学模型,分析了影响机载雷达目标定位的各种因素,计算了定位的几何精度因子(GDOP),通过仿真,得到了各误差因素综合影响下目标定位精度结果。目标定位精度分析为雷达系统设计,特别是雷达目标如何在数字地图下对目标进行准确定位提供了理论依据。     

有源无源一体模式下目标定位及其精度分析

在分析两站无源交叉测向平面定位的基础上,提出一种测向、时差联合定位的模型, 并分析了其定位原理和精度;推导了组网雷达的探测精度表达公式,并比较了单站、两站、 三站雷达定位精度的差异。在此基础上,结合有源组网探测的优点和无源侦察只被动接收、 不辐射信号的优点,提出了有源无源一体模式下的目标定位模型及其定位精度分析,并对五 站定位中的两种不同情况进行了仿真和分析。仿真结果表明,有源无源一体模式下的目标定 位方式能有效地对目标进行定位并有良好的定位精度。     

战场侦察雷达技术概述

首先介绍了战场侦察雷达的特点和主要功能.在天线、信号处理、数据处理、伺服等领域采用了各种技术,从而保证战场侦察雷达在具有强烈地杂波的复杂环境下,能够探测并提取目标信息,完成作战使命.最后简介了战场侦察雷达的技术发展趋势.     

国外直升机载毫米波火控雷达技术发展现状

本文介绍了国外几种典型的武装直升机载毫米波火控雷达，并对其功能、技术指标、关键技术进行了分析。     

临近空间双基地雷达系统误差对定位精度的影响

针对地发空收临近空间双基地雷达站址波动造成目标定位误差的问题,建立了三坐标临近空间双基地雷达目标三维定位的数学模型,采用解析几何法推导了定位精度的几何分布（Geometrical Dilution of Precision,GDOP）,仿真分析了站址误差对目标三维定位精度的影响。研究表明,站址误差对目标三维定位精度的影响较小,不同坐标轴坐标的误差对目标定位精度影响大小不同。另外,系统对相对站址方向侧向低空来袭目标三维定位精度较差,对于相对站址方向正向来袭目标三维定位精度较高。     

直升机载雷达侦察系统总体设计

本文在讨论直升机载雷达总体需求的基础上,介绍了直升机载雷达侦察系统的组成和功能,总结了系统总体设计中涉及到的关键技术,并对关键技术的解决措施进行了分析。     

无线定位新技术及发展趋势

介绍了多种无线定位新技术，指出GPSOne是各种技术之间取长补短的混合定位新技术，并且从定位原理、定位特点、应用领域等方面对GPSOne进行了分析。GPSOne将GPS与CDMA网络晶结合，克服了传统GPS在有障碍物或信号较弱时定位困难甚至无法定位的问题，是迄今为止性能最佳的无线定位技术。     

The moderating effect of self-esteem on consumer responses to global positioning in advertising

The study investigates consumers' responses to global positioning in advertising from the perspective of self. It is suggested that consumers' attitudes toward the brand advertised through global positioning are influenced by their ideal selves and cosmopolitan orientations and these influences are moderated by one's self-esteem level. Study 1 shows that attitudes toward the globally positioned brand are more positive for those with ideal selves that are more congruent with personal traits associated with globally positioned brands, but only for those with high self-esteem. Interview results from study 2 suggest that low self-esteem informants make use of the global brands associated with ‘Western’ as a means of signaling their social selves in order to obtain social approval and that high self-esteem informants attend to ad content, whether the ad employs global or local positioning.     

NLOS环境下移动台位置与速率估计

NLOS (Non-line of Sight)误差是定位中的主要误差来源,直接影响了定位的精度 。在MIMO（Multiple Input Multiple Output）系统中,基于NLOS信道模型的定位方法成为 解决NLOS定位误差问题的利器。基于此提出一种新颖的几何方法,仅采用两条NLOS路径就可 计算MS(Mobile Station)的位置,并且只需要利用单个基站便可完成MS的定位,克服了基站 数目过少无法准确定位MS的缺陷。在此基础上,还给出了最小二乘与最大似然算法利用多条 NLOS路径来改善定位精度的方法,并利用它对NLOS环境下运动的MS进行定位跟踪。理论分析 和仿真结 果都证明该定位方法在NLOS环境中对MS定位的有效性与精确度。     

An Investigation of Ghana's Tourism Positioning

ABSTRACT

The purpose of this paper is to gain a deeper understanding of Ghana's tourism positioning and whether a literature-derived positioning framework can further elaborate the latter. Using the face-to-face long interviews among key policy makers, marketing managers and experts, and observation techniques, data were collected and analyzed via the inductive reasoning approach. The results show that Ghana's tourism positioning aim is built around perceptions of a “com petitive middle class tourist destination,” i.e., “profit and status” through the pursuit of “functional” positioning objective. Positioning strategies including “service”, “value for money”, “culture”, “selectivity”, “attractiveness”, “reliability”, “manpower development”, “quality controls” and “ecology” are pursued in order to achieve the aim and objectives. The latter are managed/positioned in the “primal” positioning life cycle stage. Conclusions, managerial implications, future research directions and limitations are noted.     

Positioning strategies and congruence in the positioning of high‐end indigenous and foreign retailers in sub‐Saharan Africa: An illustration from Ghana

This article examines the employment of positioning strategies through the lens of international retailing for assessing congruence in the positioning of both indigenous and foreign retailers in Ghana. Six retailers—three indigenous and three foreign—are examined in a triangulated method, each through an in‐depth case study. The results show that the dominant positioning strategies consistently pursued by both indigenous and foreign retailers in Ghana are “service,” “reliability,” and “attractiveness.” Although indigenous retailers (relative to their foreign counterparts) employ more strategies, the majority of foreign retailers exhibit close‐to‐ideal congruence among managers' intentions, actual practice, and customers' perceptions. The findings show that foreign and indigenous retailers pursue varying positioning strategies in the marketplace, further complementing the utility of Western‐developed typologies of positioning strategies in a sub‐Saharan African marketplace. Moreover, the results reveal how indigenous retailers have embraced branding, further attesting to the changing and competitive nature of the Ghanaian marketplace.     

一种小尺寸极化阵列及其高精度定位波束形成

提出一种偶极子天线单元构成的极化敏感阵列用于全球卫星导航信号的接收,经过阵列信号波束形成后,在抗干扰的同时保留卫星导航信号中载波相位测量值的准确性,可用于基于载波相位测量的高精度差分定位。与传统的圆极化天线阵列相比,该阵列具有阵元构造简单、尺寸小的特点。通过建立极化阵列接收信号模型,分析了天线极化和波束形成算法对卫星导航信号相位的影响,给出了相适应的相位中心稳定的数字波束形成算法。仿真验证了分析的正确性和算法的有效性。     

Retailers’ Price Positioning and the Motivational Profiling of Store‐Brand Shoppers: The Case of Spain

In recent years, retailers have worked to advance store‐brand strategies, leading to greater success and higher congruence with the retailer's positioning. In this new competitive context, this research aims to characterize store‐brand shoppers in terms of motivation and benefits sought, as well as analyze, on the basis of congruence theory, the moderating role of a retailer's price positioning on store‐brand shopper characterizations. The empirical study combines survey and household panel information related to leading retailers in Spain; the findings reveal that store‐brand shoppers are motivated by their price sensitivity, whereas they are less sensitive to service quality and name brands. However, the retailer's price positioning exerts a moderating effect on shopper profiles: In less price‐oriented retail chains, store‐brand purchases seem motivated less by price and more by quality, brand awareness, and brand reputation.     

基于PSO-BP算法的无线传感器网络定位优化

在研究现有定位算法的基础上，针对基于接收信号强度指示(RSSI)定位模型中的参数易受环境影响等问题，提出了一种新型的粒子群优化(PSO)算法与后向传播（BP）神经网络相结合的算法。BP网络算法权值的修正依赖于非线性梯度值，易形成局部极值，同时学习次数较多，需先通过粒子群算法进行优化。为了提高定位精度，首先采用速度常量法滤波处理，然后通过改进的混合优化算法对BP神经网络初始权值和阈值进行优化，并分析算法的性能。试验中隐层节点个数采用试错法，从12到19变化，以确定合适数目。实验结果表明，与一般加权算法和传统BP算法相比，改进的混合优化算法可大幅改善测距误差对定位误差的影响，同时可使25 m内最小定位误差小于0.27m