Buck斩波电路电流连续与电流断续的比较研究

对降压斩波电路负载加反电动势其电流在不同情况下发生的连续和断续现象进行了研究。根据分段线性化思想,推断出降压斩波电路输出电流在断续情况下的条件,给出了其在电流断续的计算公式,为其实际应用提供了方便。     

谐振直流环软开关电路的技术研究

阐述了应用于电压型逆变器的谐振直流环电路的工作原理,给出了其在MATLAB/Simulink中的仿真模型和仿真结果。通过仿真结果得出,谐振直流环电路可实现零电压开通,使开关损耗为零,但是电压u Cr谐振峰值很高,增加了对逆变器开关器件耐压的要求。     

基于几何平均数的风光互补发电系统MPPT控制策略研究

根据风光互补发电系统的输出特性,研究了一种基于几何平均数的最大功率跟踪控制策略。首先,利用风力和光伏发电系统MPPT分别计算出下一时刻的电压占空比,然后利用几何平均数求出两个占空比的平均值。其次,用所求平均值控制风光互补发电系统的输出电压,从而保证风光互补发电系统工作在最大功率点。最后,通过MATLAB/Simulink进行了仿真分析,其结果验证了控制策略的有效性。     

并联Buck TL直流变换器控制研究

为了降低开关管电压应力和提高负载功率,本文提出了并联三电平直流变换器方案。分析了三电平直流变换器的工作原理及其控制策略,在Matlab/Simulink平台上搭建仿真模型,实现了输出电流均流和飞跨电容稳压控制,验证了并联三电平直流变换器拓扑的优点,样机试验表明了该变换器及其控制的合理性和有效性。     

含锂电池储能的船舶电力系统模型预测控制研究

由于船舶运行的特殊性和负载波动的复杂性,严重影响船舶电力系统的稳定性,因此引入了能量存储技术,降低电网的波动。根据发电机和锂电池的状态空间模型,建立了含锂电池储能的船舶电力系统,并提出了一种基于模型预测控制的船舶电力系统。在含有负载波动的情况下,使发电机和锂电池的输出能够稳定跟随负载的变化,从而满足负载的需求。并将整个系统在Matlab/Simulink中进行实例仿真,仿真结果表明,在模型预测控制下的船舶电力系统能够很好地满足负载波动需求,明显改善船舶电力系统的稳态性能,增强船舶电网的稳定性。     

武器装备重载运输车辆状态监测系统设计与实现

本文针对大型武器重载运输车辆存在的信息化程度不高,测试性、维修性、保障性设计不足等问题,对某型车辆进行了加改装,建立了开放式通用化状态感知和采集体系结构,安装智能传感器、健康信息处理平台、接口适配设备、信息监测处理设备等实现对车辆底盘、电站、电子设备和液压系统等关重件的综合健康状态信息采集和监测。本系统可以为各级指挥人员提供即时装备健康状态信息,有利地支持装备精确维修和远程支援。     

Large-scale evacuation network optimization: a bi-level control method with uncertain arterial demand

To improve the efficiency of large-scale evacuations, a network aggregation method and a bi-level optimization control method are proposed in this paper. The network aggregation method indicates the uncertain evacuation demand on the arterial sub-network and balances accuracy and efficiency by refining local road sub-networks. The bi-level optimization control method is developed to reconfigure the aggregated network from both supply and demand sides with contraflow and conflict elimination. The main purpose of this control method is to make the arterial sub-network to be served without congestion and interruption. Then, a corresponding bi-objective network flow model is presented in a static manner for an oversaturated network, and a Genetic Algorithm-based solution method is used to solve the evacuation problem. The numerical results from optimizing a city-scale evacuation network for a super typhoon justify the validity and usefulness of the network aggregation and optimization control methods.     

A new approach for improving the performance of freight train timetabling of a single-track railway system

A new approach for improving the performance of freight train timetabling for single-track railways is proposed. Using the idea of a fixed-block signaling system, we develop a matrix representation to express the occupation of inter- and intra-station tracks by trains illustrating the train blocking time diagram in its entirety. Train departure times, dwell times, and unnecessary stopping are adjusted to reduce average train travel time and single train travel time. Conflicts between successive stations and within stations are identified and solved. A fuzzy logic system is further used to adjust the range of train departure times and checks are made to determine whether dwell times and time intervals can be adjusted for passenger and freight trains at congested stations to minimize train waiting times. By combining manual scheduling expertise with the fuzzy inference method, timetable efficiency is significantly improved and becomes more flexible.     

“工厂法”沉管隧道早期性能的足尺试验研究

由于沉管隧道管段体积大、结构形式复杂、施工工艺复杂,容易因温度、收缩以及约束等原因,造成管段结构在预制阶段出现危害性裂缝,进而影响结构的服役性能和耐久性能。文章依托在建港珠澳大桥沉管隧道工程实例,开展了足尺试验,对"工厂法"沉管管节关键部位的温度和应变发展实施了监测,分析对比了温度发展规律和应变发展规律。分析结果表明:在早期因混凝土水化热引起温度上升,整个管段结构膨胀受拉,温度到达峰值后逐渐下降,结构也收缩恢复;但由于混凝土自收缩等因素的存在,结构最终收缩受压。研究所提供的试验结果可作为深入进行数值分析的一个基础。     

沉管隧道预制管节顶推滑移系统摩擦试验研究

为了针对某大型沉管隧道预制管节的顶推滑移系统选择合适的摩擦面材料,文章对该顶推滑移系统的四组拟采用摩擦面材料(不锈钢板-PTFE、不锈钢板-NGE、普通钢板-PTFE、普通钢板-NGE)进行了静、动态摩擦系数测试。利用20 000 k N压剪试验机、采用双剪法进行了模拟测试试验。试验结果表明:(1)四组被测试摩擦面的摩擦系数中,不锈钢板与PTFE板的最小,普通钢板与PTFE板的最大;(2)锂基润滑油和水对减小不锈钢板与PTFE板之间的静、动摩擦系数效果都十分明显,但锂基润滑油对摩擦系数的减小效果会随着油层被挤压变薄而逐渐减弱。该试验结果为该顶推滑移系统的摩擦面材料选择以及摩擦面润滑处理措施提供了重要参考依据。