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.     

某车型高压配电系统接动力电池插件高压互锁端子回缩问题改进

汽车高压配电系统(PDU)是汽车高压电能的集散、分配关键件,将来自动力电池的高压电能,通过各相关控制、经过高压继电器及熔断器准确传递至各高压用电器。相关传递是经过配电系统上高压线束及插件实现的,为确保安全,相关插接件上设置有高压互锁端子,利用低压电路监控高压电路连接状态,避免人员触电风险。相关高压互锁检测电路,是通过各插接件上的高压互锁端子实现传递的。当插接件间高压互锁端子出现回缩,系统为确保安全、将切断高压,直到问题解决。     

沥青路面空隙率分布规律研究

空隙率是沥青路面最重要的体积参数之一,合适的空隙率是沥青路面长期使用能力的重要保证。一直以来,由于条件所限,无法进行路面空隙率数据的大规模采集,只能假设空隙率符合正态分布,而其真实分布规律却不得而知。使用无核密度仪采集沥青路面大量空隙率分布数据,利用拟合优度的Х^2检验及偏度、峰度检验拒绝空隙率分布的正态假设。     

预应力混凝土梁荷载正应力分布试验研究

预应力混凝土受弯构件因外荷载作用产生的断面正应力分布基本符合线性分布。在受拉区完全可以用线性分布公式计算混凝土拉应力,在受压区混凝土边缘处按线性分布公式计算则误差较大。在进行重要预应力受弯构件设计时,需要校核受压区混凝土边缘压应力。本文对此进行了试验研究,此试验结果可作为设计校核参考,文中还给出了设计校核的参考公式。     

并联结构换热器模块中冷却空气流量的分配

为提高车辆换热器模块的匹配设计能力,针对冷却风在并联结构换热器模块中的流量分配进行数值模拟和试验研究。在计算中把复杂的翅片结构简化为多孔介质模型,并采用RNGk-ε湍流模型进行模拟。通过换热器模块的风洞试验对数值计算结果进行验证。结果表明由于各换热器的阻力特性不同,流量的分配与设计时的理想状态存在较大的差异,阻力小的换热器中风速高,相对流量变大。