京张高铁八达岭长城站清污排水分离系统设计

京张高铁八达岭长城地下车站埋深达102 m,车站具有规模大、洞室群复杂、周边环境敏感的特点。基于保护生态环境的绿色设计理念,创新性提出地下车站清污排水分离系统的设计概念。详细介绍车站包括进、出站通道、站台层及设备用房的特殊结构布置形式,对站内各部位排水排放量进行分析计算,并结合各部位结构特点进行针对性的排水设计。考虑清水系统经过防排水措施的有效疏导,再经过排水管路、管沟自行排出车站;污水系统采用真空抽排方式提升至室外污水压力井;废水汇入通道楼扶梯下集水坑及废水泵房提升至室外废水压力井,在排水过程中清水与污废水排放路径达到完全分离,达到了清水可利用、污废水可纳入市政的环保目的。     

Influence of slip boundary on flow separation and drag of flow past bluff body at high Reynolds numbers北大核心CSCD

［Objectives］Flow separation increases the drag and noise of underwater vehicles, and influences the controllability of their control surfaces. Therefore, the influence of slip caused by superhydrophobic surfaces on drag reduction and flow separation is studied. ［Methods］A partial slip boundary condition is developed, and the flow around a circular cylinder and foil with a slip boundary at high Reynolds numbers are numerically simulated. ［Results］The results show that the when the slip length increases, the flow around the cylinder goes through three stages: the turbulent Kármán vortex street, laminar Kármán vortex street and non-separation Stokes flow. The drag coefficient increases first and then decreases, and the vortex shedding frequency increases. For flow around a foil, the separation position moves downstream until the separation region disappears when the slip length increases, and the drag coefficient decreases while the lift coefficient increases. ［Conclusions］The results of this study show that for flow past bluff body at high Reynolds number, the slip boundary can control flow separation and reduce drag effectively, providing technical support for the application of superhydrophobic surfaces for the flow control of underwater vehicle appendages. © 2022 Journal of Clinical Hepatology. All rights reserved.     

A linear complementarity method for the solution of vertical vehicle–track interaction

A new method is proposed for the solution of the vertical vehicle–track interaction including a separation between wheel and rail. The vehicle is modelled as a multi-body system using rigid bodies, and the track is treated as a three-layer beam model in which the rail is considered as an Euler-Bernoulli beam and both the sleepers and the ballast are represented by lumped masses. A linear complementarity formulation is directly established using a combination of the wheel–rail normal contact condition and the generalised-α method. This linear complementarity problem is solved using the Lemke algorithm, and the wheel–rail contact force can be obtained. Then the dynamic responses of the vehicle and the track are solved without iteration based on the generalised-α method. The same equations of motion for the vehicle and track are adopted at the different wheel–rail contact situations. This method can remove some restrictions, that is, time-dependent mass, damping and stiffness matrices of the coupled system, multiple equations of motion for the different contact situations and the effect of the contact stiffness. Numerical results demonstrate that the proposed method is effective for simulating the vehicle–track interaction including a separation between wheel and rail.     

单通道混合信号粒子滤波盲分离算法的快速实现

粒子滤波可以处理非线性非高斯问题,可以应用于混合信号的盲分离中,是一种有效的盲分离算法。但是粒子滤波算法存在一个很大的缺陷,其复杂度太大,为了减少粒子滤波运算时间、提高运算效率,通过对粒子滤波实现过程中的符号向量进行前置扩维,从而改进了粒子滤波实现方法。仿真结果表明：改进后的算法在运算速度上相比之前有了比较明显的提升。     

浅谈高速公路客货分离设计的理念与方法

目前,国内高速公路客货分离设计研究领域尚处于空白。该文在分析我国当前客货混行的高速公路弊病的基础上,对客货分离的必要性和适用条件作了论述,同时结合客货分离高速公路的咨询设计经验,对客货分离高速公路规划设计的某些关键技术作了初步研究。     

“虚拟起算点法”计算复曲线匝道立交桥线位数据

结合苏嘉杭高速公路苏州北互通立交桥的线位计算及施工放线测量,介绍互通式立交匝道曲线线位数据的计算方法,尤其对于复曲线采用虚拟起算点法计算其线位数据。结果表明:该方法计算线位数据的准确性和可应用性补充了教材和专业书缺乏对复曲线线位数据计算公式的空白。     

分离机制下一种互联网安全接入方法

重点研究身份与位置分离机制下源地址真实性保障方面的方法,提出了身份与位置分离网络中唯一且不变的终端身份标识EID结构,并设计了一种保障源地址真实性的安全接入方法,并且给出了相应的协议流程和协议格式,保证了身份与位置分离网络中源地址即终端身份标识EID的真实性.最后使用SVO形式化逻辑对其安全性进行了证明.     

ADS-B空管监视系统误差分析与研究

在空中交通管制中,利用监视设备提供的航空器飞行动态,管制员就可以为航空器配备飞行间隔,防止航空器与航空器相撞.监视设备存在的误差会对飞行间隔产生较大的影响.对比二次雷达系统,基于ADS-B的侧向间隔研究是当前的重点.文中通过分析监视系统信号处理流程,得出ADS-B监视误差主要有GPS接收机误差、数据链误差和系统延时误差组成,并阐述了各部分对于侧向间隔的影响.     

船用丝网除雾器分离效率计算

丝网除雾器是船舶发动机及舱室空调进气过滤系统的重要组成部分,对于分离效率的计算,先前研究者的计算公式误差较大且有一定的局限性.在前人理论的基础上提出一定的假设,对模型的设置进行改进,推导出一个在不发生夹带和液泛情况下丝网除雾器对入口液滴分离效率的计算公式.并引入数值模拟的方法对丝网除雾器进行两相流模拟,通过流场分析对结果进行修正.与实验值对比表明:文中的公式达到了更高的精度,在工程应用中可以作为设计的预估手段.     

盲信号处理在机电声学监测与诊断中的应用

机械噪声信号和振动信号一样,蕴含了机械设备运行状态的重要信息,当设备状态发生改变时,其声学特性同样会发生改变。但是,待识别的目标信号和其它设备的信号以及噪声信号混杂在一起,一般很难直接从测量的声信号中获得有用的信息。因此,排除或抑制干扰信号或背景噪声,准确地从低信噪比的混合信号中提取出待识别的目标信号,对声学监测与诊断方法十分关键,而盲信号处理技术为机械声学信号的分离提供了一个有力的解决手段。该文对盲信号技术在机械装置声学监测与诊断中的研究现状进行了概述,为盲信号进一步应用于机械中的声学分析打下基础。