机电设备无失效数据的可靠性评估

利用对数正态分布函数的性质获得了各检测时刻新的Bayes估计,进而给出了母体参数的估计,并对机电设备的可靠性数据进行了处理。     

列车制动力分配决策及其在不完整信息条件下的协调

探讨了列车制动时制动力的分配方法,以及由于故障或其它原因导致制动所需信息不完善的情况下,各车厢电、空制动力的协调策略,并可根据实测减速度进一步进行制动功率的调整.提出几种有着实际替代意义的方案并分别进行误差分析.分析结果表明,制动决策信息不完整的条件下,通过不同的协调策略进行的制动力决策会产生一定的误差,但其误差值可控制在允许的范围之内.在网络故障或其他原因导致制动决策信息不完整时有着实际的替代意义.     

新型GFRP组合梁桥的空间分析

对拉挤成型GFRP组合桥面板和工字形钢梁组合而成的新型GFRP组合梁桥进行了空间有限元分析,通过对横隔板、纵梁跨径及间距等参数的研究,得到该组合梁桥横向分布系数随上述参数变化的规律.     

某型配电柜空间热场分析

以某型配电柜为研究对象,采用传热学计算方法,计算在环境温度下配电柜内的温度场.利用计算结果的参考作用,对配电柜外壳进行散热优化.计算与试验结果表明,配电柜外壳改进设计合理,内部温升指标均可满足规范要求.仿真研究分析的方法和结论对配电柜散热设计具有参考价值.     

功率混合型燃料电池汽车动力系统的恒压式能量分配算法

分析了功率混合型燃料电池汽车动力系统的特征,给出了功率混合型动力系统能量分配算法的实用设计原则,阐述了该型动力系统适用的恒压能量分配方式,并依据提出的设计原则进行了能量分配算法设计。在燃料电池城市客车“清能3号”的应用中,又提出一种分模式控制解决方案。实验证明,所设计的算法能综合考虑动力系统的部件安全性、动力性和经济性,具有一定的应用价值。     

港口岸边动力配电箱外壳防护等级的选用

通过浅析GB/T4942.2-93《低压电器外壳防护等级》,叙述港口岸边使用的配电箱防护等级要求,以及现有产品在设计制造上存在的不足,讲述选用的方法,避免因配电箱存在防护能力差所引起使用不够安全的缺点,提高现代化港口建设的技术水平。     

基于改进蚁群算法的交通分配研究

交通分配是交通规划诸多问题中被国内外学者研究得最深入、取得研究成果最多的内容。但是把蚁群算法应用到交通规划中在国内外都不多见。介绍蚁群算法在交通流分配中的应用。     

Instantaneous frequency estimation of multi-component Chirp signals in noisy environments

A classical time-varying signal,the multi-component Chirp signal has been widely used and the ability to estimate its instantaneous frequency(IF) is very useful. But in noisy environments,it is hard to estimate the IF of a multi-component Chirp signal accurately. Wigner distribution maxima(WDM) are usually utilized for this estimation. But in practice,estimation bias increases when some points deviate from the true IF in high noise environments. This paper presents a new method of multi-component Chirp signal IF estimation named Wigner Viterbi fit(WVF) ,based on Wigner-Ville distribution(WVD) and the Viterbi algorithm. First,we transform the WVD of the Chirp signal into digital image,and apply the Viterbi algorithm to separate the components and estimate their IF. At last,we establish a linear model to fit the estimation results. Theoretical analysis and simulation results prove that this new method has high precision and better performance than WDM in high noise environments,and better suppression of interference and the edge effect. Compared with WDM,WVF can reduce the mean square error(MSE) by 50% when the signal to noise ration(SNR) is in the range of -15dB to -11dB. WVF is an effective and promising IF estimation method.     

Influence on the hydrodynamic performance of a variable vector propeller of different rules of pitch angle change

To design a more effective blade pitch adjustment mechanism,research was done on changes to the hydrodynamic characteristics of VVPs(Variable Vector Propeller) caused by different rules for changing pitch angle. A mathematical method for predicting the hydrodynamic characteristics of a VVP under unsteady conditions is presented based on the panel method. Mathematical models for evaluation based on potential flow theory and the Green theorem are also presented. The hydrodynamic characteristics are numerically predicted. To avoid gaps between panels,hyperboloidal quadrilateral panels were used. The pressure Kutta condition on the trailing edge of the VVP blade was satisfied by the Newton-Raphson iterative procedure. The influence coefficients of the panels were calculated by Morino's analytical formulations to improve numerical calculation speed,and the method developed by Yanagizawa was used to eliminate the point singularity on derivation calculus while determining the velocities on propeller surfaces. The calculation results show that it's best for the hydrodynamic characteristics of the VVP that pitch angle changes follow the sine rule.     

赣南红层滑坡分布规律的映射分析

在对赣南地区红层滑坡及其环境背景资料调查的基础上,分析滑坡与自然环境及人工作用的映射关系,运用数理统计与图表分析,揭示了滑坡与其形成因素之间的内在关系,探讨了区域滑坡的分布规律与形成特征,为全面研究赣南区域性红层滑坡的机理和防治提供了参考依据.