外海沉管浮运安装作业窗口管理及工艺计划研究

沉管出坞浮运安装是港珠澳大桥岛隧工程中的关键性工程,也是一个连续的、不间断的施工过程。为了降低施工风险,结合船机设备能力,提出作业窗口管理系统,针对每步施工工序提出针对性的作业限制条件,以此寻找最佳的作业时期。潮汐条件是作业窗口因素中的关键因素,根据潮汐预报数编制24~36 h连续的浮运安装工艺计划,选择在最优的水文气象条件下,按照作业窗口管理系统严格按照计划进行作业。经过33节沉管浮运安装的现场验证,浮运安装作业窗口管理系统满足项目要求,有效保障了浮运安装安全,有效降低了施工风险和成本。     

郑州市中心区铁路跨线桥上部结构施工方案比选与实施

郑州市中心区铁路跨线桥为(106+248+106)m双塔单索面跨线斜拉桥,其上部结构跨越货运铁路、客运铁路、站场专用线等多条铁路。针对该桥结构特点和施工难点,将跨线桥主梁分为A、B、C区:A区位于斜拉桥的两端,远离铁路限界,采用支架法现浇;C区为主跨中央139m范围,位于铁路专用线上方,采用挂篮悬浇施工;B区为桥塔两侧的对称区段,直接跨越铁路运营线,通过比选,2号塔B区主梁采用挂篮悬浇方案,3号塔B区主梁采用转体方案。施工中在铁路上方设置铁路防护屏蔽网,采用宽幅全封闭挂篮技术解决了铁路上方施工净空有限的难题,将转体分次进行,压缩单次"天窗点"时间,减少了施工对既有铁路运营的干扰和影响。     

未来空域窗体制下小口径舰炮反导效能分析

针对高射速小口径舰炮如何进行防空反导的问题,文章论述了未来空域窗的构造和设计,并通过仿真比较不同射击误差协方差矩阵和空域窗半径下的毁伤效能,得出不同射击协方差矩阵和空域窗半径影响了未来空域窗毁伤区域的大小。因此,在保证一定命中概率的前提下,通过调整射击误差协方差矩阵和未来空域窗半径可以有效提高空域窗毁伤区域的大小,从而在目标大范围机动的情况下,保证了舰炮的反导效能。     

复杂周期信号的等间隔序列分选

分析各种周期信号在直方图上的规律,提出一种等间隔序列方法来分选复杂周期信号,利用等间隔序列比原序列含有更丰富的周期信息,减小了直方图方法在复杂信号环境中判别信号周期的级数和复杂性,从而提高了分选"周期性信号"的速度.     

A kinematic wave approach to traffic statics and dynamics in a double-ring network

Recently there has been much interest in understanding macroscopic fundamental diagrams of stationary road networks. However, there lacks a systematic method to define and solve stationary states in a road network with complex junctions. In this study we propose a kinematic wave approach to defining, analyzing, and simulating static and dynamic traffic characteristics in a network of two ring roads connected by a 2 × 2 junction, which can be either an uninterrupted interchange or a signalized intersection. This study is enabled by recently developed macroscopic junction models of general junctions. With a junction model based on fair merging and first-in-first-out diverging rules, we first define and solve stationary states and then derive the macroscopic fundamental diagram (MFD) of a stationary uninterrupted network. We conclude that the flow-density relationship of the uninterrupted double-ring network is not unique for high average network densities (i.e., when one ring becomes congested) and unveil the existence of infinitely many stationary states that can arise with a zero-speed shockwave. From simulation results with a corresponding Cell Transmission Model, we verify that all stationary states in the MFD are stable and can be reached, but show that randomness in the retaining ratio of each ring drives the network to more symmetric traffic patterns and higher flow-rates. Furthermore we model a signalized intersection as two alternate diverge junctions and demonstrate that the signalized double-ring network can reach asymptotically periodic traffic patterns, which are therefore defined as “stationary” states in signalized networks. With simulations we show that the flow-density relation is well defined in such “stationary” states, and asymptotic traffic patterns can be impacted by signal cycle lengths and retaining ratios. But compared with uninterrupted interchanges, signalized intersections lead to more asymmetric traffic patterns, lower flow-rates, and even gridlocks when the average density is higher than half of the jam density. The results are consistent between this study and existing studies, but the network kinematic wave model, with appropriate junction models, is mathematically tractable and physically meaningful. It has offered a more complete picture regarding the number and type of stationary states, their stability, and MFD in freeway and signalized networks.     

基于雷达和视觉技术的车辆跟踪窗口

针对基于视觉技术的运动检测鲁棒性差、计算量大的缺点,提出一种融合雷达与视觉信息建立车辆跟踪窗口的方法。采用动力学模型描述车辆运动,通过基于雷达量测的扩展卡尔曼滤波(EKF)估计,确定目标初始位置,然后根据灰度信息自适应调整跟踪窗口的中心位置及尺寸,快速而准确地建立起以目标形心为中心且适合目标大小的跟踪窗口,缩小了后续图像处理区域。三维场景仿真实验证明,该融合方法能快速有效地建立起目标的跟踪窗口。     

汽车电动车窗控制电路设计

详细介绍汽车电动车窗控制部件的功能和技术参数,解决了新车型电动车窗控制电路设计问题。     

基于余弦窗FFT算法的智能轮胎实时不平衡量振动信号处理系统研究

目前智能轮胎实时侦测技术的研发已成为汽车技术发展的主要方向之一,智能轮胎实时信号处理系统是实现智能轮胎实时侦测功能的关键。本文提出一种基于余弦窗FFT算法的智能轮胎实时不平衡量振动信号处理系统,通过传感器、信号放大器、滤波板、数据采集卡、计算系统等实现行驶车辆智能轮胎振动信号的采集、放大、调理、预处理和处理,其中,计算系统采用余弦窗FFT算法,结合电子地图路面信息系统,有效获取智能轮胎实时不平衡量振动信号的幅值与相位。该系统能有效处理异步采样信号,满足智能轮胎在线监测快速、准确的测量需求。     

分舱形式对圆柱壳结构声学性能影响研究

为研究舱壁布置形式对圆柱壳结构声学性能的影规律,文章应用有限元方法对等间距与不等间距分舱圆柱壳模型的振动响应进行了计算,以此为输入可计算获得壳体的均方法向速度级声学传递函数,并在典型频率处应用波数谱分析方法将壳体空间域振动场转换到波数域上,对壳体的振动进行波形分离与量化,分析获得了舱壁等间距布置与不等间距布置圆柱壳在典型激励下的结构声学性能,并解释其机理.研究表明:对垂向激励,圆柱壳不等间距分舱相比等间距分舱具有较好的结构声学性能,但对轴向激励,两者区别不明显.若将不等间距分舱与局部结构补强措施相结合,则可使得圆柱壳在两典型工况下均能获得更优的结构声学性能.     

一类非线性微分方程周期解存在的条件

本文用非线性泛函分析的理论和方法研究了一类非线性徽分方程周期解的存在性, 并给出了周期解存在的条件。