Link16数据链导航功能实现与改进

基于同步的相对导航与精确定位技术是Link16数据链运行的关键。针对国内文献对该 技术介绍较少的情况,分析了相对导航的基本原理,研究了利用往返计时报文实现精确同步 的方法和步骤,建立了相对导航解算方程以及相对栅格与地理栅格坐标之间的数据转换模型 ,最后提出了一种用GPS/IMU数据融合和卡尔曼滤波方法提高导航精度的方案。应用结果表 明,该方案能显著提高数据链的导航精度。     

基于“间隙-接受”的环岛十字交叉口优化模型研究

随着我市交通出行量的大幅增长,交通堵塞情况日益加重,这给交通管理部门在交通组织上提出了新的要求,需要完善科学的交通管理方法和模式。城市道路十字交叉路口是交通流汇集的重点区域,在十字交叉口使用环岛的交通组织方式具有自组织性强、车流顺畅的有点,但是环岛内车流与入岛车流的冲突也限制了环岛的通过能力,通过科学研究找到合理、高效的管理方法,可以提高环岛的通过能力,减缓交通拥堵。为了解决这一问题,国内外学者进行了广泛的研究。Zhenke[1],刘会斌[2]等研究了环形交叉口信号灯控制的方法,Brilon[3],Tanner[4],陈晓明[5]等研究了交通环岛通过能力的优化方法,Stuwe[6],廖铄澔[7]等研究了交通环岛信号灯配时方法,为交通环岛综合组织优化做出了贡献,但由于交通环岛组织优化问题收到多种因素的影响,需要考虑多重因素,建立合理的数学模型才能找到更好的组织和管理方法。本文建立了基于"间隙-接受"模型的城市道路十字交叉口环岛数学模型,通过研究交通环岛内车流速度与进入环岛交通流量的数学关系,找出稳定状态下环岛的最大通过能力,分析了模型中进入环岛车道数、岛内车道数与稳态情况下"间歇-接受"通过能力的关系。对于有信号环岛组织模型,又找出了最大通过能力下的环岛内车流密度值,以此将环岛内的车流有序化、规范化、流量固定化,通过将环岛优化策略与交通信号控制相结合,合理优化相位时间缓解入岛车流与环岛内车流的冲突,以求达到最大的通过能力。     

On the relation between the market-to-book ratio, growth opportunity, and leverage ratio

The negative relation between the market-to-book ratio and leverage ratio is one of the most widely documented empirical regularities in the capital structure literature. Most related studies take this negative relation as given and debate about its economic interpretation. We show that firms with higher market-to-book ratios face lower debt financing costs and borrow more. The relation between the market-to-book ratio and leverage ratio is not monotonic and is positive for most firms (more than 88% of COMPUSTAT firms and more than 95% of total market capitalization). The previously documented negative relation is driven by a subset of firms with high market-to-book ratios.     

An Exploration of the Conditional Timing Performance of UK Unit Trusts

Abstract:  We examine the conditional market timing performance of UK unit trusts between January 1988 and December 2002. We find no evidence of superior conditional market timing performance by UK unit trusts either across different portfolios of trusts or by individual trusts. We also find that benchmark investing is significant for UK unit trusts and trusts have high numerical risk aversion to deviations from the benchmark. Our findings suggest that UK trusts act like benchmark investors.     

The Recognition and Timing of Deferred Tax Liabilities

Abstract:   This paper examines the characteristics of firms that account for deferred tax liabilities related to government investment grants under an extended adoption timing period. Not only the recognition but also the timing decision is associated with changes in future performance and changes in the debt structure. Recognisers outperform non‐recognisers in the future, while early recognition is related to post recognition performance but only for those firms that currently perform well. Changes in the balance sheet structure are also related to both decisions. Firms with recent increases in the debt level tend to postpone recognition, while currently well‐performing firms that increase their future debt level are less likely to recognise deferred taxes.     

Stability, Asymmetry and Seasonality of Fund Performance: An Analysis of Australian Multi‐sector Managed Funds

Using a sample of Australian Multi-sector trusts we examine selectivity and market timing performance and extend the analysis to include the relatively new measure of volatility timing. This is of particular relevance to our data set, as high levels of volatility persistence are prevalent in Australia. In addition we consider the stability, asymmetry and seasonality of the various performance and risk measures. A survivorship adjustment procedure is also employed in order to assess the impact of survivorship on selectivity, market timing and volatility timing performance.     

OFDM系统的多符号改进算法

针对OFDM训练符号同步算法中存在的大采样数据而导致捕获时间过长的问题。提出了一种多符号改进算法。该算法应用对多个符号等间隔取样并共轭相乘累加的方法，在采用小数目的采样数据时就可以取得较好的性能，同时缩短了定时捕获时间，克服了原来算法中存在的问题。最后，仿真表明该算法的有效性。     

一种基于信号机制在UNIX实时应用中快速传递信息的方法

在多进程的实时应用程序中，进程之间往往需要通过传递一些信息来达到资源共享的目的。介绍了一种基于信号机制在UNIX实时应用中的两个进程之间实现快速传递信息的方法，提高了实时性。