多运营商高铁隧道移动网络覆盖方案

高铁移动网络覆盖是国内三大通信运营商的一个重点,而高铁隧道内移动网络覆盖更是运营商的一大难点痛点。文章根据我国中部省份某高铁线路覆盖规划实例,采用“设备+POI+泄漏电缆”模式,即三家运营商信号源设备通过同一POI(point of interface,多系统接入平台)接入,信号输出到泄漏电缆进行隧道覆盖,隧道口场坪站安装宽频切换天线对隧道外进行延伸覆盖,通过链路预算合理布置各运营商主设备信号源,从而实现隧道到室外的无缝覆盖。最后,根据已有成熟网络覆盖解决方案,对未来5G高铁隧道移动网络覆盖方案进行了探讨。     

基于多体动力学仿真的冰箱助吸器优化设计

某款冰箱在关门过程中,门体在多个小角度处出现悬停的现象,影响用户的体验。针对这一问题,基于多体动力学仿真对冰箱助吸器进行了优化设计。将助吸器变形量、刚度、有效力臂接触位置点至铰链轴心连线长度,以及这一连线与接触位置法向夹角作为关键因子,研究关键因子与设计目标之间的关系,进行助吸器的结构设计与性能评估。在此基础上,基于多体动力学仿真,实现助吸器的优化,并形成最终设计方案。基于多体动力学仿真进行优化设计,可以缩短开发周期,提高设计效率,具有较高的实用价值。     

Hybridized ant colony algorithm for the Multi Compartment Vehicle Routing Problem

Multi Compartment Vehicle Routing Problem is an extension of the classical Capacitated Vehicle Routing Problem where different products are transported together in one vehicle with multiple compartments. Products are stored in different compartments because they cannot be mixed together due to differences in their individual characteristics. The problem is encountered in many industries such as delivery of food and grocery, garbage collection, marine vessels, etc. We propose a hybridized algorithm which combines local search with an existent ant colony algorithm to solve the problem. Computational experiments are performed on new generated benchmark problem instances. An existing ant colony algorithm and the proposed hybridized ant colony algorithm are compared. It was found that the proposed ant colony algorithm gives better results as compared to the existing ant colony algorithm.     

Protection of power transformer using multi criteria decision-making

Power transformers are protected by different relays that operate independently. Malfunction of each relay has a major role in reducing the reliability of the protection system. In order to mitigate the main drawbacks of the power transformer relays, an overall protection scheme is presented in this paper. This scheme proposes a novel multi criterion algorithm using decision-making based on fuzzy logic. In this paper the outputs of restricted earth fault relay and a directional check unit, are combined with the output of the differential protection relay. Therefore, problems that are pertaining to independent operation of each relay have been mitigated and the relays cover protection blind spots of each other. The improved power transformer protection (IPTP) scheme enhances the sensitivity and reliability of the power transformer protection. Extensive simulations are used to measure the effectiveness and merit of the proposed IPTP relay. The above efforts result in a multi criteria approach for protection of power transformers.     

A new wavelet based fault detection,classification and location in transmission lines

This paper deals with the application of wavelet transforms for the detection, classification and location of faults on transmission lines. A Global Positioning System clock is used to synchronize sampling of voltage and current signals at both the ends of the transmission line. The detail coefficients of current signals of both the ends are utilized to calculate fault indices. These fault indices are compared with threshold values to detect and classify the faults. Artificial Neural Networks are employed to locate the fault, which make use of approximate decompositions of the voltages and currents of local end. The proposed algorithm is tested successfully for different locations and types of faults.     

Comparative study of the optimal operation of methane reforming process in cylindrical and spherical reactors using multi-objective optimization

We present a multi-objective optimization (MOO) based study of the optimal operation of methane reformer for spherical reactor and compare the results with the ones for the cylindrical reactor. We considered three objective functions for this comparative study, namely maximization of hydrogen production, minimization of carbon dioxide emission, and minimization of power loss due to pressure drop in the reactor. We solve four MOO problems, which include three 2-objective problems with each pair of the aforementioned three objectives. In addition, we also solve a three objective problem considering all the three objectives. The optimization variables considered for the MOO study correspond to the feed conditions. Specifically, the three variables include the inlet temperature and the molar feed ratios of oxygen to methane & steam to methane.     

Multi carrier energy systems and energy hubs: Comprehensive review,survey and recommendations

In this paper, the multi carrier energy (MCE) systems are reviewed from different point of views including mathematical models, integrated components and technologies, uncertainty management, planning objectives, environmental pollution, resilience, and robustness. The basic of MCE systems is formed by combination of cooling, heating and power (CCHP). The natural gas and electricity are the main inputs to MCE systems and the cooling, heating, and electricity are the common outputs. The regular energy converters in the MCE systems are combined heat and power (CHP), gas boiler, absorption-electrical chillers, power to gas (P2G) and fuel-cell. The generic energy storages are electrical, heating, cooling, hydrogen, carbon dioxide (CO₂) and hydro systems.     

工程机械液压多路阀试验台设计开发

工程机械多路阀试验台用于挖掘机、装载机、叉车等液压多路阀性能检测试验。设计并制造了多路阀性能测试试验台,主要设计了液压系统、电控系统与数据采集系统。试验台测试项目与技术参数都达到了国内同类产品先进水平。     

以弗莱堡市为例看当今欧洲城市新区发展趋势

通过对德国弗莱堡市在不同历史阶段的城市发展分析,展现了欧洲城市的几个典型阶段的发展特征及其空间构成特点;并以此为背景来分析建于20世纪90年代的城市新区Rieselfeld的设计思想、建设阶段和城市空间及建筑单体构成特色。