基于子空间跟踪的波束形成算法

在期望信号方向发生变化或未知的情况下，为了获得较理想的波束形成，基于ESPRIT(借助旋转不变技术估计信号参数)方法，借助受限摄动子空间跟踪算法，提出了一种改进的波束形成算法．由于该算法采用子空间跟踪技术，对期望信号导向矢量能实时跟踪，从而能抑制时变信号的指向误差．计算机仿真结果表明，该算法获得的结果与已知期望信号方向理想情况下的波束形成结果相近．     

一种处理粉粒物料运输车粉料结块的破碎装置

针对粉罐车内粉料结块的现象,提出了一种简单实用的破碎方案,即引入随车空压机喷射的气流,以破碎拥堵在出料口附近的结块,达到消除结块堵塞在出料口无法正常卸料的目的。     

Age related annual crash incidence rate ratios in professional drivers of heavy goods vehicles

ObjectivesEvidence concerning crash risk for older heavy vehicle drivers is sparse, making it difficult to assess if it is prudent to encourage older drivers to remain in the workforce in a climate of labour shortages. The objective of this study was to estimate annual crash rate ratios of older male heavy vehicle drivers relative to their middle aged peers.MethodsData utilized in this study includes all crashes meeting inclusion criteria involving heavy goods vehicles, categorised as rigid trucks and articulated trucks; this data was recorded by the New South Wales Roads and Traffic Authority. The exposure to the risk of a crash was represented by distance travelled for each vehicle type and year, by age of driver, as estimated by the Australian Survey of Motor Vehicle Use. Negative binomial regression modelling was applied to estimate annual crash incidence rate ratios for male drivers in various age groups.ResultsA total of 26,146 crashes occurred in New South Wales during 1999–2006, involving a total of 54,191 vehicles; removing observations that did not meet the inclusion criteria, 19,736 observations remained representing 12,501 crashes. For rigid trucks, the incidence rate ratio for drivers aged 65+ years, compared to 45–54 year olds, was 0.74 (95% CI 0.51, 0.98). For articulated trucks, the annual crash incidence rate ratio for drivers aged 65+ years compared to 45–54 year olds was 1.4 (95% CI 0.96, 1.9), and that for drivers aged 55–64 years compared to 45–54 year olds was 1.1 (95% CI 0.83, 1.3).ConclusionsOlder male professional drivers of heavy goods vehicles have lower risk of crashes in rigid vehicles, possibly due to accrued driving experience and self-selection of healthy individuals remaining in the workforce. Thus, encouraging these drivers to remain in the workforce is appropriate in the climate of labour shortages, as this study provides evidence that to do so would not endanger road safety.     

军用光电跟踪伺服控制技术分析

针对光电跟踪伺服系统所面对的新要求,在分析其控制原理及技术要求的基础上,从经典控制、现代控制和智能控制三个方面,对军用光电跟踪伺服系统中所采用的各种控制策略进行比较分析,阐述其各自的特点以及应用场合。在此基础上,探讨了光电跟踪伺服系统及其控制技术的发展趋势。这对于根据不同的技术要求选取合适的伺服控制方法,提供了理论参考,并具有一定的现实意义。     

萧甬铁路客货运量预测及SWOT分析

铁路客货运量预测能为政策制定及运输发展规划的编制提供科学依据.以萧甬铁路为背景,在对客货运输经营现状深入分析的基础上,采用经济指标预测法、时间序列预测法等对2010年和2015年客货运量进行了预测.在综合考虑客货经营现状和客货运量预测的基础上,对萧甬铁路客货运输进行了优势、劣势、机会和威胁分析.     

基于固定延迟平滑算法的机动目标跟踪方法

为进一步提高机动目标的跟踪精度和估值算法的数值稳定性,文章基于平方根UKF（square root UKF：SR-UKF）和固定延迟平滑算法（fixed-lag smoothing）提出一种新的固定延迟平方根UKS算法（fixed-lag square root unscentedkal man smoothing：FL-SR-UKS）。数值仿真说明该算法可以有效处理机动目标跟踪问题,且状态估值精度优于SR-UKF。     

铁路建设项目实施阶段甲供物资价差调整要点

铁道部对甲供物资管理颁布了有关管理办法及实施细则,但在实际操作中,特别是在甲供物资价差调整过程中存在设计与实际不符的各种现象和因素,给计价工作带来一定的难度。此文针对按《铁路基本建设工程设计概(预)算编制办法(》铁建设[2006]113号)编制概算及实施初步设计招标的项目,阐述建设项目实施阶段甲供物资价差调整的要点,对甲供物资调差中应注意的问题进行剖析,以期进一步完善和规范价差调整工作,为今后项目的甲供物资价差调整提供参考。     

CBTC系统列车追踪运行浅析

CBTC系统是一种利用高精度的、不依赖于轨道电路的列车定位技术,实现连续式的、大容量的双向车、地数据通信.本文简要分析了基于通信的列车运行控制系统中不同等级列车的追踪运行方式,有助于进一步从系统运用的角度理解CBTC系统.     

GPS微弱信号捕获跟踪算法

在GPS微弱信号捕获算法设计中, 为提高捕获灵敏度, 采用相干积分与非相干积分结合的方式消除数据码长度对相干积分增益的影响, 采用差分相干积分减小非相干积分中的平方衰耗。为了提高信号捕获速度和精度, 利用FFT工具进行伪码与载波频率捕获, 采用延迟锁定环(DLL) 与锁相环(PLL) 实现GPS微弱信号的跟踪。最后对GPS微弱信号的捕获跟踪算法进行仿真实现。应用结果表明: 通过仿真技术能有效地复现出捕获和跟踪载噪比为25dB.Hz^-1的GPS微弱信号, 差分相干积分捕获灵敏度比相干-非相干积分高0.8dB, 频率捕获误差小于1.25Hz, 码捕获误差小于0.1码元。     

基于小波和逻辑法的多目标跟踪数据处理

智能交通系统(ITS),常常要采用传感器对交通目标进行实时定位监控,但被跟踪目标的不确定性以及原始数据通常存在大量噪声的干扰,这对数据融合的精度产生很大的影响.针对这一问题,采用小波变换多尺度分解与重构结合阈值消噪的方法对原始数据进行降噪处理,它能很好的保持原始信号的瞬变特征,并对处理后的数据采用逻辑法进行目标航迹起始...