星形曲折延边三角形接线平衡变压器的阻抗匹配与数学模型

从基本方程组出发,分析了星形曲折延边三角形接线平衡变压器的运行特性.根据理想平衡变压器的技术条件给出了星形曲折延边三角形接线平衡变压器的通用阻抗匹配关系,扩展了阻抗匹配空间,证明以前得到的结果只是阻抗匹配空间的子集,增大了产品设计自由度.给出了变压器一次侧与二次侧间电气量变换关系和相坐标下的节点导纳矩阵,为进行牵引供电系统有关问题的分析计算奠定了基础.同时,从电气特性表达式上揭示了星形曲折延边三角形接线、星形延边三角形接线、星形三角形接线变压器之间的演化关系.     

微带天线作为车载卫星电视接收天线的理论探讨

从方向性函数等电视接收天线的几个重要方面对微带天线进行了理论分析，并对其作为车载卫星电视接收天线进行了可行性的综合论证。     

单线铁路隧道机械化配套方案在乌兹别克斯坦安-琶铁路隧道的实践应用

结合乌兹别克斯坦安-琶铁路隧道施工实际情况,按机械化配套施工方案进行了全隧道的设备配置,通过过程调整和测定等方式,成功在该隧道实践应用,达到了较高的施工水平,在施工周期内实现了单头掘进平均200 m/月的施工进度,达到了预期的施工目标。通过本项目机械化配套的实践应用,解决了单线铁路隧道施工无法实现全机械化配套的难题。     

Novel Chaotic Fragile Watermarking Algorithm for Image Authentication

Taking full advantage of the randomicity of chaotic system and its extreme sensitivity to the initial value, a new chaotic fragile watermarking algorithm is proposed. In the algorithm, the location key is looked as a logistic chaotic initial value for iteration to create a location matrix. According to this location matrix, a mapping image is generated and the embedding location of watermarking in image blocks is identified. Then, the watermarking sequence, which is related with the mapping image blocks and generated by H6non chaotic map, is embedded into the least significant bit (LSB) of the corresponding location in each block. Since the image content and watermarking are staggered, the algorithm has a higher security. Simulation results showed that the algorithm can detect and locate the tamper in watermarked images with an accuracy of 2 x 2 block pixels. At the same time, the watermarking images has good invisibility, and the original image is not required when extracting watermarking.     

基于供需平衡的公路网评价方法研究

为了分析公路交通供需之间的适应程度,按性质和功能对区域公路交通需求和供给进行分类,分别从高速公路、一级公路和双车道公路三方面对公路交通需求和供给进行量化分析,分析各等级公路每个车道的适应交通量,研究各参数的计算方法,引入路网供需匹配度的评价指标,构建路网供需匹配度的评价模型,提出评价标准,为地区公路网建设规模的合理性评价提供有益的借鉴.     

电动车辆新型独立驱动系统设计与参数匹配

为了弥补现有轮边驱动电动车辆驱动系统的缺陷,设计了一种新型双电机独立驱动系统。该系统采用两台永磁同步电机作为动力源,依靠两套减速齿轮组分别进行减速,用短半轴来带动车轮旋转。在系统构型设计的基础上,根据车辆动力学理论,进行了包括电动机、减速器和电池在内的动力系统参数匹配,并进行了整车性能的仿真分析。仿真结果满足指标要求,证明了匹配方法的正确性。该驱动方案和匹配方法为新型动力系统开发提供了一定借鉴。     

Self-organizing map based quality assessment for resistance spot welding with featured electrode displacement signals

To classify the quality of the resistance spot welding process, a relationship between the welder electrode displacement curve characteristics and the weld shear force has been explored. Eleven statistical features of the displacement signals are extracted to represent the welding quality. Self-organizing map (SOM) neural networks have been employed to discover their quantitative relationship. In order to identify the influence of various displacement curve features, all of the available combinations have been used as inputs for SOM neural networks. Further we analyze the impact of each feature on the classification results, yielding the best quality-indicative combination of characteristics. There is no determinant relationship between the welding quality and the level of expulsion rate. The quality of welding is most impacted by the maximum electrode displacement, the span of welding process and the centroid of the electrode displacement curve. The experiments show that SOM is feasible to assess the welding quality and can render the visualized intuitive evaluation results.     

基于动态建模仿真的纯电动汽车动力性分析

针对纯电动汽车的动力性分析问题,根据电机的测试数据,建立基于Simulink的动态仿真模型,并进行纯电动汽车动力性指标的仿真计算。结果表明:动态建模仿真方法比传统的动力性计算方法更方便更有效,能反映纯电动汽车在实际道路行驶时负载突变状态下整车的动力性能特点。     

基于最佳熵匹配的多通道海量数据快速搜索

为快速、准确地从海量试验数据中获取所需的与某一工况或状态对应的数据,通过分析常规时序搜索方法存在的问题,根据信源熵的原理和特点,提出了一种基于最佳熵匹配的多通道海量数据快速搜索方法.该方法用“状态匹配”代替常规的“时序匹配”,以检测熵值为主,所需参数少,对邻近时间的依赖性小,降低了因通道间时间同步产生的误差,搜索步伐大,速度快.结果表明,对于一些特定的工况,搜索速度可提高数千倍,匹配准确度提高,主要参数的相对误差均在0.05以下.     

基于等值线搜索带的地磁匹配算法

针对TERCOM算法在地磁匹配应用中存在的不足,提出了基于等值线搜索带的改进匹配算法,将地磁基准图上的匹配搜索区域缩小到航迹起始点地磁测量值对应的地磁场等值线附近区域,从而减少匹配搜索时间和计算量.仿真实验结果表明,该算法在保证匹配精度的前提下,能够有效降低匹配计算时间,提高匹配算法的实时性.