一种适用于宽带短波通信OFDM系统符号定时同步的新方法

针对宽带短波通信正交频分复用（OFDM）系统,提出了一种不需要数据辅助的高效符号定时同步方法。该方法利用OFDM符号中的空载波不传输任何数据这一特性,通过最小化空载波上的数据能量来将符号定时点锁定在安全区域内,从而完成符号定时同步。该方法可以有效对抗多径效应,适用于短波通信系统。最后将该方法与Al-Dweik同步方案在宽带短波信道条件下进行了仿真对比,结果表明该方法有着更精确的符号定时同步性能,并且适用于各种星座图调制。     

短波信道质量评估技术综述

短波信道质量评估设备按技术体制分为两大类,分别是独立信道探测系统和嵌入式探 测系统。介绍了两类系统的基本原理、目前研究和应用现状以及存在的问题,指出应将两类 技术进行结合,根据通信业务进行针对性的信道分析以提高评估效率。最后对其发展方向进 行展望,以期为短波实时信道估值方面的研究提供参考。     

基于耦合加载的低剖面天线设计

设计了一种小型化双频天线。通过在单极子天线上引入寄生耦合的方法,即在单极子 顶部引入耦合加载板,既保证了单极子天线的辐射全向性又减小了电小天线的分布电容 ,从而使该天线具有宽频带、低剖面特性。采用仿真软件Ansoft HFSS进行仿真和优化,优 化结果表明：该天线工作频率为824～960 MHz/1 710～2 690 MHz（驻波比小 于等于2） 。根据仿真模型制作了一款天线,实测驻波带宽可达811～1050MHz/1580～2660 MHz,且在水平面内辐射全向方向图。该天线在限制尺寸的情况下有效地展宽了带宽。     

交叉极化干扰消除技术研究

针对双极化频率复用系统中的交叉极化干扰问题,提出了全数字交叉极化干扰消除 器的设计方案,研制了具有交叉极化干扰消除、解调功能的一体化工程样机。测试结果表明 ,该设备对交叉极化干扰的消除效果明显。     

公开展示权与作品传播的版权保护

作品公开展示包括现场展示和传播展示两种形式,传播展示作品则对版权人和作品使用者利益的影响更大。随着电视广播、有线电视、移动视听设备、计算机网络技术等新兴传播手段飞速发展,传统的复制权、表演权、发行权已不足以保护版权人的利益和满足作品使用者获取信息的需要,公开展示权与发行权、复制权相比较更适合保护网络作品传播展示。     

对益贫式增长内涵的理解：一个文献综述

益贫式增长是对穷人有利的经济增长,它关注经济增长、不平等和贫困三者之间的关系。自20世纪90年代末以来,益贫式增长成为国内外学术界研究的一个热点问题,不同学者对其内涵的理解也存在很大差异。本文主要从益贫式增长的定义、思想及理论基础等方面对国内外学者已有的研究成果进行梳理,并进行简要评述。     

上市公司高管过度自信对现金股利政策的影响

抛弃经典财务理论中理性经理人的假设,将规范研究与实证研究相结合,以2006—2010年我国沪深两市A股上市公司作为研究样本,用管理者的相对薪酬、持股状况和实施并购次数构建综合指标来衡量公司高管的过度自信程度,从公司高管过度自信的视角重新审视上市公司的现金股利分配行为。研究结果表明:管理者过度自信的上市公司倾向于少发放现金股利来增强内部融资;上市公司的成长性越强,管理者的过度自信对现金股利分配决策的影响越显著。     

Cross-channel integration – is it valued by customers?

It has been common for retail companies to use multiple channels simultaneously. However, simultaneous use is only the first step in creating a customer-centric multichannel system that demands channel synergies rather than parallel retail formats. Therefore, the perceived integration of customer-related functions and processes between the channels of multichannel systems is analyzed with respect to its significance for customer loyalty and usage of a multichannel system. Drawing on a sample (n) of 981 customers, the results indicate that linkages between retail channels positively affect customer loyalty and verify the importance of establishing a well-integrated – ‘seamless’ as perceived by the customer – multichannel system.     

Effects of intra-brand competition between private labels and manufacturer brands: Empirical results from the Italian market

A proliferation of private labels in European food retailing has been evident for several years now. The purpose of this study is to analyze the impact of competition between manufacturer brands and private labels on assortment and pricing practices by Italian grocery retailers. Previous studies emphasized both pro-competitive and anti-competitive effects of private label development. In this study, within an empirical analysis based on scanner data from Symphony IRI Group, all fast moving consumer goods product categories are investigated over a period of two years (from September 2008 to September 2010). The empirical results indicate that in Italy there is no clear and strong evidence of decreases in manufacturer brands' assortments, prices, and turnover caused by a proliferation of private labels. In particular, analyzing at the same time all categories and all retailers' data in the Italian Market there is not much evidence for the existence of a strategic trade-off between manufacturer's and retailer's brands.     

Emigration and wages: The EU enlargement experiment

The enlargement of the European Union provides a unique opportunity to study the impact of the lifting of migration restrictions on the migrant sending countries. With EU enlargement in 2004, 1.2 million workers from Eastern Europe emigrated to the UK and Ireland. I use this emigration wave to show that emigration significantly changed the wage distribution in the sending country, in particular between young and old workers. Using a novel dataset from Lithuania, the UK and Ireland for the calibration of a structural model of labor demand, I find that over the period of five years emigration increased the wages of young workers by 6%, while it had no effect on the wages of old workers. Contrary to the immigration literature, there is no significant effect of emigration on the wage distribution between high-skilled and low-skilled workers.