高速铁路通信、信号系统联调联试方案的探讨

随着我国高速铁路的不断发展,列车运营时速的不断提高,为保证列车的安全运行,通信、信号系统的重要性越发突出。为验证通信、信号系统的性能,就必须在工程静态验收合格后进行通信、信号系统的联调联试,为高速铁路的开通提供科学依据。联调联试主要采用检测列车、测试动车组、综合检测列车和相关检测设备在规定测试速度下对全线通信、信号系统进行综合测试,并对全线通信、信号系统进行调试、优化,使系统功能达到设计要求。为全面验证系统功能形成一套切实可行的联调联试方案是十分重要的。     

一种基于小波分解的直扩信号检测方法

针对直接序列扩频（DSSS）信号检测的问题，提出了一种对接收信号时域自相关进行小波分解的方法。该方法对于进行了载波调制的直扩信号，其所在频带未知时无法设计前置滤渡器，从而造成检测性能下降的情况，给出了一种可行的解决方案。计算机模拟表明，在该情况下，本方法具有较好的检测性能。     

高校扩招引发教育信号贬值的机理分析

本文运用劳动市场信号发送理论,分析我国高校扩招引发的教育信号贬值的内在机理.扩招降低了进入大学的学习成本,导致了教育信号的过度投资及分离均衡的教育水平提高(即就业门槛提高),文凭的信号作用贬值.扩招后不同群体的信号投资方式和境遇不同,大学生的信号投资激励增强,而高中生缺乏信号分离自己.信号投资的一个重要特点是,通过雇主与雇员的相互博弈过程会产生自增强效应.如果高校不断扩招,会导致信号投资的不断攀升,形成信号投资泡沫.     

基于LFM模型的高动态弱GPS信号载波捕获

根据极大似然估计理论,通过载波频率和频率变化率分段对消、快速傅里叶变换(FFT)结果选大估计载波频率和频率变化率,实现载波信号捕获,建立了高动态全球定位系统(GPS)载波的线性调频(LFM)信号模型,并给出了算法的具体实现。详细分析了该算法中检测统计量的分布特性,推导了恒虚警准则下的检测门限,并讨论了其中关键参数的设计。仿真结果表明,该算法可以实现对18 dBHz的GPS高动态信号的载波捕获。     

民营上市公司现金股利信号传递效应实证研究

系统考察股利分配预案公告日我国民营上市公司现金股利信息的信号传递效应,并在研究方法上对我国当前该领域研究中所存在的缺陷进行了弥补。在严格控制了盈余信息、公司规模等因素后,分别对2001-2003年度我国民营上市公司股利分配预案公告日前后样本(除送、配方案之外)的“纯”现金股利分配预案的市场反应进行了分析。结果发现,股利分配预案公告日前后,民营上市公司发放现金股利并没有受到市场排斥,其超常收益显著为正。     

航管应答机的中频数字化设计

提出了一种航管应答机的中频数字化设计方案,并详细论述了如何应用带通采样定理、正交相干检波理论实现接收信号的中频直接数字化,同时对高速模拟/数字变换器(ADC)、低通滤波器、基带信号处理等各主要功能模块进行了介绍,并给出了相关的计算和仿真.     

Determinants of Currency Crises in Emerging Markets: The Case of Turkey

This paper investigates possible determinants of currency crises in Turkey. We use three different techniques—namely, the signaling approach, structural model, and Markov switching model with monthly data for the period 1992-2004. The results show that money market pressure index, real-sector confidence index, and public-sector variables are significant in explaining currency crises. Hence, one can say that banking crises lead to currency crises. Central banks' real-sector confidence index may be a good leading indicator for currency crises.     

Risk signal, financial derivatives transactions and the Indonesian GAAP

Motivated by the accounting events of firm＇s default related to derivatives and other financial instruments transactions, this study is aimed to investigate the capability of accounting information to signal the risks associated with the use of financial derivatives for hedging. Hypothesis are developed based on the theory and empirical evidences of manager＇s motive to use derivatives for hedging （Berkman ＆ Bradbury, 1968; Dune, et al., 2003） as well as signaling theory of accounting information （Ball ＆ Brown, 1968; Beaver ＆ Dukes, 1972; Jensen ＆ Meckling, 1976; Megginson, 1997）. The hypotheses are formulated in the Ordinary Least Square model. The study uses Statistical Product and Service Solutions （SPSS） version 14 as software to conduct the statistical tests. Non-bank and non-financial institutions firms with financial derivatives transactions listed in Indonesian Stock Exchange during 2001 to 2006 are chosen as the sample. Determinations of the time frame has considered the timing of introduction of revisions of accounting standard on derivatives and other financial instruments in Indonesia PSAK 50 Financial Instruments： Presentations and Disclosures which was published in July, 1998, as well as PSAK 55 Financial Instruments： Recognition and Measurements which was published in 1998. Based on the sample selections procedure and the completeness of the data required by the model, 24 firms listed during 2001-2006 or equal to 66 firm-years observations were identified as the data to be tested. Empirical evidences suggests that Indonesian GAAP is capable of providing signal associated with： （1） Fair value exposures related to manager＇s motive to reduce the cost of financial distress; （2） Cash flow exposures related to manager＇s motive to practice tax arbitrage as well as to overcome underinvestment problems; （3） Interest rate risks related to manager＇s motive to avoid the risk default due to limitations of debt covenants; （4） Forex risk related to manager＇s motive to control forex exposures caused by foreign operations as well as foreign sales.     

计轴自动站间闭塞结合电路的改进

针对计轴自动站间闭塞结合电路中存在区间设备故障不关闭出发信号的联锁失效安全隐患进行了成因分析,提出了电路改进方案,并在现场设备中进行实际应用,证明了其可行性。     

铁路既有线信号电缆径路防护的探讨

文章从铁路既有线信号电缆径路施工配合、日常维护管理方面探讨电缆径路安全防护工作,提出“超前防范、提前介入、主动配合、严格把关”的施工配合原则及“全过程控制、零挖断”的防护理念,做好监督与配合工作,从完善标准、明确责任、规范检查制度、电缆日常管理等方面探讨如何做好维护工作.