LFMCW雷达多目标加速度和速度估计方法

在线性调频连续波(LFMCW)雷达中,加速度运动目标回波存在多普勒频谱畸变现象,造成目标检测性能和参数估计精度损失。本文提出对同一距离单元上的多个目标的多普勒信号进行修正的多项相位变换,能够以较小的运算量,准确估计多个目标的速度和加速度,达到改善目标的检测性能和提高参数估计精度目的。     

接近香农限的编织卷积码设计与仿真

本文主要阐述了斜纹编织卷积码的编码结构、迭代译码以及活性距离和交织器对其误码性能的影响等基本概念。通过系统仿真,在AWGN信道下发现斜纹编织卷积码的系统性能与系统传输帧长和编码器个数都有很大的联系,其误码性能十分接近香农限,且没有错误地板效应。     

基于软件通信体系结构的OFDM波形实现

探讨了软件定义无线电开放的软件通信体系结构(SCA),实现了其核心框架,在此基础上给出了OFDM波形应用的开发过程,这些都为以后其他波形应用的开发提供了基础。     

基于并行判决法的PCTH-UWB系统性能分析

伪混沌跳时序列(PCTH)最近提出应用于UWB系统。本文分析了PCTH-UWB的工作原理,提出了并行判决法,与直接判决法进行了比较,理论分析及仿真结果表明并行判决法可提高PCTH-UWB系统性能。     

射频识别(RFID)产业发展格局研究

近年来,在沃尔玛、麦德龙等跨国零售巨头的推动下,射频识别(RFID)技术受到了越来越多的厂商的关注。从射频识别技术的基本概念、分类和产业链结构出发,结合射频识别产业的标准现状,对近年来国内外射频识别产业的发展格局进行分析研究,并对中国如何发展射频识别产业提出自己的一些建议。     

The Relation Among Targets' R&D Activities, Acquirers' Returns, and In-Process R&D in the US

Abstract:  Using a sample of 129 mergers and acquisitions (M&As) in the US between publicly traded acquirers and targets in research and development (R&D) intensive industries over the period of 1994-2004 and a size- and industry-matched sample, we examine the relation among targets' R&D activities, the probability of acquirers' writing-off in-process R&D (IPRD), and acquirers' returns around the time of M&A announcements. We find that firms acquiring targets with higher R&D investments tend to write off some of the acquired R&D assets upon the completion of the M&As. We also find that the median cumulative abnormal return during the three days around M&A announcements for acquirers with subsequent IPRD write-offs is −2.73% while the return for acquirers without IPRD write-offs is −0.60%. This suggests that acquirers' stock returns around M&A announcements are much lower when investors expect acquirers to expense IPRD. The results are consistent with our conjecture that acquirers tend to write-off IPRD when they acquire overvalued targets. We also find that IPRD write-offs do not increase earnings or stock returns of acquirers after M&As, which is inconsistent with an earnings management hypothesis.     

Real (adaptation) options and the valuation of equity: some empirical evidence

Data from 1,374 firms across four broad industrial groupings are used to assess the contribution that real (adaptation) options make to overall equity values. The analysis indicates that real (adaptation) options make a significant contribution to the equity value of firms with a market to book ratio (of equity) of around unity or less. As the market to book ratio grows beyond this level, however, the contribution made by real (adaptation) options decays quickly away and equity values are mainly comprised of the present value of the dividends that firms are expected to pay. This means that for around one in every five of the firms in our sample real (adaptation) options make a significant contribution to overall equity value. Thus, while linear equity valuation models would seem to be appropriate for the substantial majority of firms on which our sample is based, there is a sizeable minority of firms where real (adaptation) options have a significant impact on equity values. For this latter group of firms there will be a non-linear relationship between equity value and its determining variables. This has important implications for the regression procedures that are applied in this area of accounting research.     

Cultural lag and international communication The Case of Japan

In this special first issue contribution by Dr. Nagai in his capacity of Supervisory Editor of this new Journal, attention is given to the often neglected influence of the cultural lag on communications and its impact on economic policies and international relations.     

Resurrecting the Discounted Cash Equivalent Flow

Following the debate between Chambers and Peasnell, it is argued that the correct criterion for investment appraisal is the discounted net cash equivalent flow, that is CoCoA income net of interest on wealth.