水下航行体操纵性指数与频率特性计算

本文根据水下航行体的侧-滚运动方程组，经拉普拉斯变换，求解了运动参数的传递函数；并用时域分析法与频率分析法，给出了四阶系统的操纵性指数K，T计算方法与频率特性的计算方法及其算例，以判别航行体的侧向、横滚方向运动的稳定性与机动性。     

波形竖管降膜蒸发流动与传热性能的理论研究

本文简介波形竖管降膜蒸发流动与传热的过程,通过理论分析建立波形竖管降膜蒸发传热的数学模型。采用国外一些研究者得到的理论分析与实验结果,利用无穷泰勒级数将含有多重积分的数学模型展开,得到简单实用的半经验——半理论数学模型解析式。     

梯形轨道系统动力特性及减振效果试验研究

采用锤击法,对梯形轨道系统(简称梯轨)进行动力特性试验。利用变时基传递函数细化分析方法,解决力信号时域波形精度与加速度信号频率分辨率之间的矛盾,提高低频脉冲频响分析精度。根据锤头材料的锤击特性和试验研究的频率范围,分别选择尼龙和钢制锤头进行梯轨模态和减振特性试验研究。结果表明:梯轨的低阶模态分布比较密集,基频为48.6Hz,前3阶模态的阻尼比较高,1阶阻尼比最大,达到6.64%;梯轨的工作频率约为50Hz,在梯轨工作频率之上1/3倍频程中心频率处,传递损失不随锤击力的大小而变化,梯轨的振动衰减系数为常数;梯轨具有较高的减振作用,在0～1000Hz频段传递损失在45dB左右。     

基于ArcEngine的GPS定位跟踪系统设计及实现

结合项目实际需求,分析借鉴现有系统的经验教训,通过模块化设计,基于Arc Engine组件设计,开发了具备良好移植性、扩展性和稳定性的GPS定位跟踪系统,并实现了定位数据存储、高时态地图绘制、网络数据通信等关键技术。     

Tuning of transfer functions for analysis of wave–ship interactions

Transfer functions are often used together with a wave spectrum for analysis of wave–ship interactions, where one application addresses the prediction of wave-induced motions or other types of global responses. This paper presents a simple and practical method which can be used to tune the transfer function of such responses to facilitate improved prediction capability. The input to the method consists of a measured response, i.e. time series sequences from a given sensor, the 2D wave spectrum characterising the seaway in which the measurements are taken, and an initial estimate of the transfer function for the response in study. The paper presents results obtained using data from an in-service container ship. The 2D wave spectra are taken from the ERA5 database, while the transfer function is computed by a simple closed-form expression. The paper shows that the application of the tuned transfer function leads to predictions which are significantly improved compared to using the transfer function without tuning.     

Generalized Maximum Benefit Multiple Chinese Postman Problem

This research is focused on a generalization on the Max Benefit Chinese Postman Problem and the multiple vehicle variant of the Chinese Postman Problem. We call this generalization, the Generalized Maximum Benefit k-Chinese Postman Problem (GB k-CPP). We present a novel Mixed Integer Programming (MIP) formulation for the GB k-CPP. Four different cases of the model are discussed. The first case, performs arc-routing with profits and assumes that the origin and destination for each vehicle is the same for each cycle and is given by the user. The next case relaxes the assumption that the origin and destination for each vehicle should be the same and allows the users to select possible origins/destinations for vehicles. Case three gets the origin for each vehicle as input and produces a solution based on finding the best destination for each vehicle. The last case, that is very general, allows the optimization model to select possibly different locations for vehicle origin and destination, during each cycle. The different cases are applied to a security patrolling case conducted on the network of University of Maryland at College Park campus and the results are compared.     

城市公共交通多元票制初探

借鉴国外先进经验,引进多元化公交票制是国内推进公交优先发展的重要措施.多元票制,即将乘客进行科学的分类,根据乘客的出行需求,设置不同种类的车票,以提高公交吸引力.就国内公交发展现状来看,换乘优惠的票制改革是推广多元票制的最佳切入点.     

大马力重载全驱大件牵引车分动箱油冷器设计及应用

大件牵引车是用于运输不可拆解的重型大件货物的专用车辆。其动力系统通常具有较大的马力和较高的扭矩。主要的运输工作过程中车辆处于长时间的重载工作情况,所以车辆在对与整车的动力及传动系统、冷却系统等方面的要求较高。而分动箱作为传动系统的重要组成部件,分动箱的性能对整车有着较为直接的影响。大件牵引车由于低速重载情况下长时间的工作,分动箱内的齿轮油发热严重产生高温,直接影响齿轮的性能及车辆的安全,故针对分动箱油温较高的情况,设计一套油冷器用于冷却分动箱油温,从而从根本上解决了车辆长时间处于低速重载作业过程中,分动箱油温较高对分动箱性能及齿轮使用寿命的不利影响。提高整车的可靠性和寿命,从而提高车辆的性能质量。     

汽车进气系统轰鸣声传递路径分析

为了消除进气系统带来的车内噪声问题,运用传递路径分析方法,“源-路径-响应”的分析思路,总结了进气系统噪声问题的传递路径,结合某轿车进气系统轰鸣声问题的改进,发现结构传递路径和空气传递路径对该进气轰鸣声均有重要贡献,通过降低空气滤清器安装点橡胶软垫的硬度和加强安装点车身侧支架,可有效降低车内轰鸣声。     

10kV供电系统接地危害及应对措施

本文针对我公司10kV供电系统单相接地故障,阐述了10kV中性点不接地系统的特点,以及中性点不接地系统对地电容电流超标的危害。分析了10kV供电系统单相接地的故障现象、故障原因及消弧消谐装置的优缺点,进一步提出了系统发生单相接地时的应对措施。