基于二值HT的多LFM信号检测

Wigner-Ville分布对于单分量LFM信号有很好的时频聚集性,但WVD是二次型变换,故对信号环境中复杂的多LFM信号不可避免的存在交叉项的干扰。HT可以消除交叉项的影响,能够很好的对多个LFM信号进行检测,但存在大信号淹没小信号的现象。提出二值HT能够很好的解决上述问题,为多LFM信号的检测技术提供理论依据。     

水下目标深度测量误差源分析

首先研究了在深海环境下,采用基于三阵元垂直线列阵的水声探测系统进行水下目标深度测量的基本原理.然后从随机误差和阵元配置偏差的角度,对水下目标深度测量的误差源进行了理论分析,并推导了相关公式.此外,对于相干多途水声信道干扰给水下目标深度测量精度的影响,也作了初步的理论分析.通过仿真实验,总结出各误差源对水下目标深度测量精度影响的规律,研究结果为进一步开展水下目标深度测量研究、提高测量精度奠定了基础.     

基于多层动网格技术的流固耦合方法研究

从弱耦合的角度出发,对某型跨声速风扇叶片做了第一阶扭转振动模态下的流固耦合验证计算,采用三维线性插值方法,通过商用软件ANSYS和CFX实现了计算结构动力学和计算流体力学之间的数据交换,从而使固体域与流体域顺序祸合.应用多层动网格技术解决了固体域模型在流场中运动受到流体网格尺寸制约的问题.计算结果表明,模拟结果可以预估叶轮系统的模态气动阻尼系数,具有工程参考价值.     

公路水泥混凝土路面基层顶面当量回弹模量非线性计算公式归一化的研究

鉴于1994年和2002年水泥混凝土路面设计规范中,基层顶面当量回弹模量确定过程存在的繁琐性,有必要通过回归分析,对2002年规范所提供的六个计算公式加以简化。实践表明,该简化能够满足计算要求并取得满意的效果。     

Improving maritime inventory routing: application to a Brazilian petroleum case

The crude oil offloading and supply problem (COSP) is a type of operation maritime inventory routing (MIR) problem encountered by petroleum companies. In COSP, the company not only is responsible for the ship scheduling to carry the crude oil from production sites to discharge ports but also must maintain inventory levels at both ports (production and consumption) between safety operational bounds to avoid disruptions in its crude oil production and/or refining processes. We show how to improve significantly the decision-making process in a Brazilian petroleum company using a mixed-integer linear programming (MILP) model to represent COSP. Comparison tests with a current ship-scheduling method adopted in the company indicated that the use of the MILP model increased the transportation efficiency and reduced costs by 20% on average. In addition to the quantitative gains, the use of a MILP model to solve COSP has succeeded when encountering real-life events, such as variation in production or consumption rates, berth unavailability, and changes in the storage capacities at ports.     

Development and evaluation of a statistically reliable traffic counting program

This paper reviews the existing procedures to compute the seasonal factors, growth factors, and the number of automatic traffic recorder stations (ATRs) for developing a statistically reliable traffic counting program. The review is based on, (i) theoretical evaluation of the procedures, (ii) analysis of the results obtained from applying these procedures to extensive real life data, and (iii) experience of past researchers with these methods. The paper primarily deals with existing statistical procedures for determining seasonal factors, since it is believed that these factors play the most important role in estimating Annual Average Daily Traffic (AADTs) from short counts. The procedure of cluster analysis (which is most commonly used to determine seasonal factors) is critically reviewed. The shortcomings of this method motivated the development of a different statistical procedure, based on regression analysis, to determine seasonal factors. It is shown that this newly developed method gives better results than the cluster analysis techniques. Furthermore, separate sections are dedicated to a thorough analysis of determination of number of ATR stations and computation of growth factors.     

基于GRNN的GSM-R场强覆盖预测算法

在比较Hata模型修正方法和GRNN算法场强覆盖预测效果的基础上,仿真分析了训练集构成和平滑因子选择对GRNN算法预测效果的影响,给出了训练集构成和平滑因子选择的方法;提出了电波传播环境相似系数来表征GRNN模型在不同环境下的适用性。仿真结果表明,两种传播环境的相似系数越大,由一种环境下测试数据确定的GRNN在另一环境下的预测精度越高。     

级配碎石回弹变形特性

级配碎石具有非线性的应力-应变特性,回弹模量是有效描述这一特性的参数,通过室内动三轴试验能够得到较好的模拟级配碎石回弹模量的模型。分析了影响级配碎石回弹变形特性的各种因素,并进行了试验验证。通过数据拟合发现,Uzan模型能更好地反映级配碎石的非线性回弹变形特性,且模型中的回归参数与级配中小于0.075mm筛孔的质量分数有一定的关联性。并针对影响级配碎石回弹模量的两个重要参数：级配中小于0.075mm筛孔的质量分数和含水质量分数,提出相应的取值范围建议。     

汽车操纵稳定性主客观评价数据的一种处理方法

汽车操纵稳定性主客观评价之间的相关性分析是汽车技术的重要课题。提出了汽车操纵稳定性主客观评价数据的一种处理方法．通过回归分析筛选客观参数，运用BP神经网络建立相关性模型，验证结果说明了该方法的可行性。     

基于非参数回归的快速路行程速度短期预测算法

基于北京市快速路上的检测器所采集的历史数据，经过数据筛选，剔除判别，小波滤噪平稳处理，聚类分析等过程，建立了交通状态演变系列的历史样本数据库。基于所构建的历史数据库，通过数值试验，确定了状态向量、距离匹配原则，K近邻值等参量，构建了一种基于K近邻的非参数回归短时交通预测模型，实现了对路段行程速度的短时预测。最后，利用随机选取的历史数据系列对预测模型的精度进行了检验。结果表明，预测算法的精度可以达到90％以上，可以很好地满足ITS应用系统对于交通预测数据的精度要求。