MHD mixed convection of a Cu–water nanofluid flow through a channel with an open trapezoidal cavity and an elliptical obstacle

In the current work, numerical simulations are achieved to study the properties and the characteristics of fluid flow and heat transfer of (Cu–water) nanofluid under the magnetohydrodynamic effects in a horizontal rectangular canal with an open trapezoidal enclosure and an elliptical obstacle. The cavity lower wall is grooved and represents the heat source while the obstacle represents a stationary cold wall. On the other hand, the rest of the walls are considered adiabatic. The governing equations for this investigation are formulated, nondimensionalized, and then solved by Galerkin finite element approach. The numerical findings were examined across a wide range of Richardson number (0.1 ≤ Ri ≤ 10), Reynolds number (1 ≤ Re ≤ 125), Hartmann number (0 ≤ Ha ≤ 100), and volume fraction of nanofluid (0 ≤ φ ≤ 0.05). The current study's findings demonstrate that the flow strength increases inversely as the Reynolds number rises, which pushes the isotherms down to the lower part of the trapezoidal cavity. The Nu_avg rises as the Ri rise, the maximum Nu_avg = 10.345 at Ri = 10, Re = 50, ϕ = 0.05, and Ha = 0; however, it reduces with increasing Hartmann number. Also, it increase by increasing ϕ, at Ri = 10, the Nu_avg increased by 8.44% when the volume fraction of nanofluid increased from (ϕ = 0–0.05).     

Effect of obstacle density on the travel time of the visually impaired people

Because China has put more emphasis on people with disabilities, their living conditions and protection have received increasing attention. In an emergency, the visually impaired people are limited in their ability to evacuate, especially along egress paths with obstacles. This paper studied the relationship between the travel time of visually impaired people and obstacle density in their path. Eight sighted people and 32 people with visual impairments were chosen to carry out the walking experiment. The results of the experiment showed that the travel time of sighted people was shorter than that of visually impaired people under the same obstacle and non‐obstacle situations. Based on the analysis of variance of travel time, it was clear from the results that the travel time of the visually impaired people rapidly increased when there were obstacles. When the obstacle density was kept to within a certain range, there was no obvious increase in travel time. Once the density exceeded this range, there was another obvious increase. Based on this result, it can be seen that keeping the obstacle density to within a certain range could be helpful for the visually impaired people during an evacuation when the egress paths cannot be made obstacle‐free.     

煤矿地面轨道运输矿车自动避障技术研究

介绍了煤矿地面轨道运输矿车自动避障技术。首先介绍了基于雷达的矿车前方障碍物检测技术及其相关算法,然后详细介绍了基于机器视觉的矿车前方障碍物检测系统和常用的图像处理方法以及相关的算法,最后介绍了雷达和机器视觉融合的障碍物检测技术在煤矿地面轨道运输矿车自动避障过程中的应用。     

基于透视投影的激光跟踪测量系统可视性分析

针对现有激光跟踪测量系统可视性分析方法在计算效率方面的不足，提出一种基于透视投影的激光跟踪测量系统可视性分析方法。给出了激光跟踪仪可视性分析的数学定义，利用测点与站位点之间的关系对可视性分析进行描述；利用包络盒对障碍物进行简化，同时根据障碍物、测点、站位点之间的关系，剔除了不参与可视性分析运算的障碍物；在此基础上，利用透视投影的原理，对障碍物在跟踪仪可布置平面上的投影进行了求解，并利用该投影与站位点之间是否包含的关系，得到了测点与站位点之间的可视性矩阵，结合提出的可视性势能的概念，对跟踪仪满足可视性的区域进行了求解。最后，以某飞机舱门检验工装的测量为例，验证了该方法和模型的正确性和有效性。     

楼梯升降机简介

介绍楼梯升降机的结构、参数、特点、具体应用和选购指南。     

北方城市民用建筑系统节能改造协调机制研究

热源、热网及民用建筑单体各相关部分节能改造行为协调的有效性决定了北方城市民用建筑系统节能改造的整体效果与整体收益。深入分析北方城市民用建筑系统节能改造协调障碍,提出由战略管理层、决策目标层和内部机制层组成的北方城市民用建筑系统节能改造协调机制,根据多元优化的基本准则构建北方城市民用建筑系统节能改造协调机制的概念模型,在对民用建筑系统节能改造特点剖析的基础上,提出概念模型的具体量化方法及促使该协调机制实现的相关措施,为北方城市民用建筑系统能耗水平的降低、节能改造资金的有效利用提供了新思路。     

GPS跨障碍高程传递的初步研究

本文分析了应用GPS技术实施跨障碍高程传递所存在的主要问题 ,提出了一种“天文GPS水准”方法 :首先采用GPS水准分别拟合障碍物两侧的似大地水准面形状 ,进而分别求得地面垂线偏差及其一次变化率 ;由于两侧所求的垂线偏差是属于同一系统的 (WGS 84) ,因此可根据天文水准原理 ,在顾及垂线偏差二次变化率的情况下 ,进一步求出跨障碍的高程异常差。根据以上设想进行的研究试验表明 ,“天文GPS水准”克服了单纯GPS水准无法连接不同高程系统的困难 ,对于远距离跨障碍高程传递是一种有效的高精度方法     

基于深度信息的巡逻机器人避障系统实现

针对巡逻机器人的避障导航,基于Realsense深度摄像头获取环境深度信息,在使用机载计算机对深度图像进行分层处理的基础上,设计了巡逻机器人避障导航系统,同时对巡逻机器人通信协议以及决策流程等进行了改进设计,最后在ROS机器人开源操作系统上对其进行实验及验证。实验结果表明,在相同环境下,该方法能使巡逻机器人快速、安全、有效地避开静态障碍物而到达目标点。该方法不仅能够提高避障的成功率,获得实时避障效果,而且能够降低巡逻机器人的数据处理量,有利于巡逻机器人的移植。     

基于树莓派的无人监控避障船

为了使无人船在水域能够顺利的避开障碍,提出的无人船是以树莓派为核心,包括电器驱动模块、超声波模块、红外模块、摄像头模块、LED灯、语音模块、雨滴传感器。由于考虑到水面的情况复杂,通过多传感器融合的方式进行避障,通过雷达模块进行对动态障碍的避障,通过红外进行静态避障。可以探测水面4.5m的障碍,并且精度可达7%。通过树莓派的WiFi通信技术将船体与上位机连接,可以事实观测无人船运行情况。可以广泛应用于湖泊内河作业,具有广泛的应用前景。     

基于MSP430的小车式灭火机器人设计

本设计是以MSP430F149单片机为核心的小车式灭火报警机器人,通过红外火焰传感器的数字输出进行火源寻找,并根据采集到的信号对行进方向进行调整,同时利用红外对管实现机器人避障。机器人行进过程中能够依据火焰传感器的模拟量输出估算出机器人与火源之间的距离,并利用MQ 2烟雾浓度传感器检测周围烟雾浓度。此外本设计具有液晶显示功能、蜂鸣器报警功能以及LED灯光报警功能。整体设计低能耗、低成本,实验表明：小车式机器人能够快速有效的寻找到火源,并进行灭火,适用于家庭、宿舍、加油站等小型场所。