基于无人机的高层住宅最后“一百米”配送优化

针对城市高层住宅顾客对上门配送服务的需求，借助无人机停放平台，考虑包裹异质性以及无人机在不同配送阶段的精确能耗，构建以无人机飞行成本和能耗成本最小为目标，以无人机容量、电池组容量等为约束的高层住宅无人机上门配送模型，解决“垂直位置最后一百米配送”问题。基于此模型，设计带变邻域下降(VND)搜索的混合蚁群算法(HACO-VND)，引入4个算子进行变邻域下降搜索，为了提高算法的求解性能，提出两种局部搜索算子组合，根据顾客点数量使用不同的算子组合。实验结果表明，HACO-VND算法较CPLEX在求解精度与求解时间方面更优，特别是在大中型算例中表现出较佳性能。参数分析表明，高层住宅楼层数越多，无人机单次 飞行的能耗利用率越大，无人机容量与电池组容量共同对配送方案产生影响。为以后无人机送货上门服务方面的研究提供参考和思路。     

任意桥梁截面自由扭转常数计算的快速方法

计算任意截面的自由扭转常数可采用有限元分析方法,位移法有限元计算出的自由扭转常数比理论值偏大且网格剖分尺寸大小明显影响计算速度。本文从弹性理论圣维南自由扭转问题基本假设出发,针对悬臂梁模型采用基于位移的最小势能原理和基于应力的最小余能原理两种方法,推导势能泛函和余能泛函表达式,并求得泛函的极小值从而推导出相应的有限元方程,得到两种计算自由扭转常数公式。根据推导出的有限元方程,采用三角形单元编写程序进行两种截面的计算并与理论值对比。对比结果表明,采用两种方法计算自由扭转常数并取其平均值作为最终结果相较于采用单一位移法计算其精度大幅提高,两种方法互相参考有利于解决计算结果偏大和计算量过大的问题。     

ROV attitude control based on multi-motor cooperative propulsion北大核心CSCD

[目的]为了提高遥控水下航行器(ROV)在复杂水下环境中的姿态控制性能,开展多电机协同推进的ROV姿态控制研究。[方法]首先,针对多电机系统的结构和算法,分别提出一种基于PID速度补偿器的偏差耦合结构和一种新型非奇异终端滑模控制(SMC)算法,并设计一种新颖的基于多电机协同推进的ROV姿态控制方法;然后,建立ROV的运动学和动力学模型,开展推进器组推力建模分析、解耦简化ROV动力学模型研究;最后,设计一种ROV滑模姿态控制器。[结果]仿真结果表明,所提的结构和算法可提高多电机系统的抗干扰性、同步性和快速响应能力,进而提高ROV姿态控制系统的稳定性与鲁棒性。[结论]所提方法可为ROV姿态控制提供一种新的可用方案。     

Economic and ecological optimization of electric bus charging considering variable electricity prices and CO2eq intensities

In many cities, diesel buses are being replaced by electric buses with the aim of reducing local emissions and thus improving air quality. The protection of the environment and the health of the population is the highest priority of our society. For the transport companies that operate these buses, not only ecological issues but also economic issues are of great importance. Due to the high purchase costs of electric buses compared to conventional buses, operators are forced to use electric vehicles in a targeted manner in order to ensure amortization over the service life of the vehicles. A compromise between ecology and economy must be found in order to both protect the environment and ensure economical operation of the buses.In this study, we present a new methodology for optimizing the vehicles’ charging time as a function of the parameters CO_2eq emissions and electricity costs. Based on recorded driving profiles in daily bus operation, the energy demands of conventional and electric buses are calculated for the passenger transportation in the city of Aachen in 2017. Different charging scenarios are defined to analyze the influence of the temporal variability of CO_2eq intensity and electricity price on the environmental impact and economy of the bus. For every individual day of a year, charging periods with the lowest and highest costs and emissions are identified and recommendations for daily bus operation are made. To enable both the ecological and economical operation of the bus, the parameters of electricity price and CO₂ are weighted differently, and several charging periods are proposed, taking into account the priorities previously set. A sensitivity analysis is carried out to evaluate the influence of selected parameters and to derive recommendations for improving the ecological and economic balance of the battery-powered electric vehicle.In all scenarios, the optimization of the charging period results in energy cost savings of a maximum of 13.6% compared to charging at a fixed electricity price. The savings potential of CO_2eq emissions is similar, at 14.9%. From an economic point of view, charging between 2 a.m. and 4 a.m. results in the lowest energy costs on average. The CO_2eq intensity is also low in this period, but midday charging leads to the largest savings in CO_2eq emissions. From a life cycle perspective, the electric bus is not economically competitive with the conventional bus. However, from an ecological point of view, the electric bus saves on average 37.5% CO_2eq emissions over its service life compared to the diesel bus. The reduction potential is maximized if the electric vehicle exclusively consumes electricity from solar and wind power.     

面向新型混合交通流的智能交叉口网络布局优化

考虑网联自动驾驶车辆(Connected Autonomous Vehicle, CAV)应用先进的车联网与自动驾驶技术，可以采用智能交叉口的组织形式，大幅提升交叉口的通行效率，为降低CAV与人工驾驶车辆(Human-driven Vehicle, HV)混行条件下城市交通系统的整体出行成本，提出智能交叉口在城 市交通网络中的布局优化问题，建立数学优化模型并求解。首先，基于对两类车辆行驶特性的分析，建立混合用户均衡模型，描述CAV与HV的路径选择行为；其次，从交通规划者的角度，以系统最优为目标，整合混合用户均衡模型，建立面向新型混合交通流的智能交叉口网络布局优化模型，并利用改进的遗传算法求解；最后，选取Sioux-Falls交通网络作为案例分析，验证模型与算法的有效性，并研究CAV渗透率变化对优化结果的影响。研究表明，智能交叉口在城市路网中的合理规划极大地提高了新型混行场景下城市交通系统的出行效率，同时，大幅降低了由于网联自动 驾驶单方面技术优势带来的CAV与HV的出行效率差距，增进了出行公平性。     

某款商用汽车电堆散热系统方案设计

从商用汽车电堆散热系统设计要求的实际角度出发设计系统原理图,从而进行计算匹配及选型零部件,对所选零部件进行仿真校核是否满足最初的设计要求,保证商用汽车电堆散热系统的正常工作。     

基于车辆自动定位数据的有轨电车运行效率分析与应用

结合有轨电车线路的现有车辆自动定位数据,分析有轨电车运行效率及其相关影响因素。其中,影响因素从站台、路段、交叉口3个方面进行考虑。定性分析了不同站台型式、站台位置、交叉口类型的属性特征,并量化不同路段的路段长度、所包含的交叉口个数,同时考虑了交叉口控制策略对有轨电车运行时间的影响。以某已运营的有轨电车线路为例,通过建立多元线性回归模型,从不同层面探究不同因素对已运营有轨电车线路运行效率的影响。最后用模型对有轨电车新建线路的运行效率进行预测,并提出建议。     

氢能源产业技术标准化发展现况

氢能作为一种高效、清洁、可持续利用的二次能源被认为是构建未来以可再生能源为主的多元能源结构的重要载体,以其开发和利用技术为主逐渐形成全球化氢能产业规模,氢能产业技术发展离不开氢能技术标准的推动和支撑,纵观国内外氢能技术标准化的发展及现况,我国氢能技术与国外还存在很大的差距,在液氢制取与储运、船用氢能燃料电池动力系统、加氢站关键设备及部件等技术方面需要加大科研投入,预研相关技术标准,提前谋划布局,以标准引领我国氢能技术及产业快速、高质量发展。     

海洋核动力平台全频段舱室噪声预报与降噪方案研究

随着新规范对船舶及海上工作平台提出了更高要求，舱室噪声的控制及优化设计越来越受到人们的关注。本文首先对全频段舱室噪声预报软件——VA One软件统计能量分析理论及软件概况进行了阐述，其次应用该软件对海洋核动力平台进行几何建模与仿真计算。通过对舱室仿真计算结果与标准指标要求的对比分析，在设计阶段提出了海洋核动力平台舱室空气噪声综合治理降噪方案，该措施可以缩短建造周期、降低制造成本，提高海洋核动力平台的舒适性与安全性，具有十分重要的经济效益和社会效益。     

A signal decomposition method based on repeated extraction of maximum energy component for offshore structures

Contrary to most signal decomposition methods that usually decompose an original signal into a series of components simultaneously, a novel approach based on repeated extraction of Maximum Energy Component (MEC) is proposed. The approach starts from determination of the MEC referring to the estimated Power Spectral Density (PSD) function, and then represents the MEC by employing an exponential function to fit the original signal. By defining a stopping criterion based on two adjacent estimated PSDs, each MEC can be accurately extracted with an improved performance throughout the entire signal decomposition. To verify the proposed method, a single degree-of-freedom system subject to harmonic loads has been examined. Numerical results show that the analytical response can not only be decomposed into four MECs corresponding to the excitation and the system, respectively, but also provide an accurate estimation of natural frequency and damping ratio of the system. Meanwhile, by observing results from the Ensemble Empirical Mode Decomposition (EEMD), Variational Mode Decomposition (VMD) and Prony based on state-space model (Prony-SS), an improved decomposition accuracy has been achieved from the proposed approach. Furthermore, experimental data from the Norwegian Deepwater Programme and two sets of field-test data from one fixed offshore platform and an offshore wind turbine have been used to demonstrate the correctness of the developed signal decomposition method. It is noted that divergence in results by Prony-SS can be observed when a very large model order is used, while the proposed method provides the better decomposition and reconstruction of signals.