Fractional-order load-frequency control of interconnected power systems using chaotic multi-objective optimization

Fractional-order proportional-integral-derivative (FOPID) controllers are designed for load-frequency control (LFC) of two interconnected power systems. Conflicting time-domain design objectives are considered in a multi-objective optimization (MOO)-based design framework to design the gains and the fractional differ-integral orders of the FOPID controllers in the two areas. Here, we explore the effect of augmenting two different chaotic maps along with the uniform random number generator (RNG) in the popular MOO algorithm—the Non-dominated Sorting Genetic Algorithm-II (NSGA-II). Different measures of quality for MOO, e.g. hypervolume indicator, moment of inertia-based diversity metric, total Pareto spread, spacing metric, are adopted to select the best set of controller parameters from multiple runs of all the NSGA-II variants (i.e. nominal and chaotic versions). The chaotic versions of the NSGA-II algorithm are compared with the standard NSGA-II in terms of solution quality and computational time. In addition, the Pareto optimal fronts showing the trade-off between the two conflicting time domain design objectives are compared to show the advantage of using the FOPID controller over that with simple PID controller. The nature of fast/slow and high/low noise amplification effects of the FOPID structure or the four quadrant operation in the two inter-connected areas of the power system is also explored. A fuzzy logic-based method has been adopted next to select the best compromise solution from the best Pareto fronts corresponding to each MOO comparison criteria. The time-domain system responses are shown for the fuzzy best compromise solutions under nominal operating conditions. Comparative analysis on the merits and de-merits of each controller structure is reported then. A robustness analysis is also done for the PID and the FOPID controllers.     

基于CFX的搅拌器功率计算

通过CFX软件对六平直叶圆盘涡轮搅拌槽进行数值模拟,分析其流场规律。利用模拟结果计算搅拌轴功率,并应用公式法进行验算,为各种搅拌器的功率计算提供参考。     

电控正流量挖掘机分工况功率匹配研究

针对目前电控正流量挖掘机系统研究较少、空载时能量损失大、发动机与主泵功率不匹配以及节能控制效果不佳的问题,搭建基于AMESim和Simulink的挖掘机电液系统联合仿真平台,提出一种双变量泵的发动机-泵恒功率控制方法。通过样机仿真实验以及分工况功率匹配研究,验证搭建的电控正流量挖掘机系统的正确性以及分工况功率匹配的有效性。仿真实验结果表明：设计的仿真模型以及功率匹配策略表现良好,在仿真和实验中,不同的工况模式下均可以保证泵的恒功率特性,可以实现对发动机的功率控制,发动机功率可以得到充分利用。     

Optimization of an organic photovoltaic device via modulation of thickness of photoactive and optical spacer layers

We examine the modulation effects of thicknesses of both a photoactive layer (a bulk-heterojunction (BHJ) of poly(3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM)) and an optical spacer of a transparent metal oxide, for power conversion efficiency optimization of organic photovoltaic devices. The redistribution of the optical intensity at the photoactive layer via the thickness modulation of both layers is taken into account, to produce three-dimensional (3D) plots as a function of both layer thicknesses of 0 to 400 nm range (5 nm step), for the device efficiency optimization. The modulation pattern of absorption is produced in the 3D plot as scanning the thicknesses of both layers as a result of modulation of interference between incoming and reflected light, which can be secured by changing the effective optical path length between two electrodes of a photovoltaic device. It is also seen that the case of inserting the spacer of the higher refractive index demands finer adjustment of the spacer layer thickness to achieve the optimum device efficiency.In addition, the series resistance of the photoactive layer of the thickness range of 0 to 70 nm is taken into account to provide the 3D plots as a function of the scanned thicknesses of both layers. Inclusion of the series resistance of the photoactive layer, which is also the function of its thickness, in the simulation, indicates that the series resistance can influence qualitatively the dependence of power conversion efficiency (PCE) on the thicknesses of both layers. We also find that minimization of series resistance, e.g., by device annealing, allows not only the relevant voltage to increase but also the optimum thickness of the photoactive layer to increase, leading to more absorption of light.     

Chip geometry and cutting forces in gear power skiving

This paper describes a new virtual model for predicting the uncut chip geometry and cutting forces in power skiving, which is a high-speed, versatile gear cutting process. The developed kinematic model is applied in a dexel-based solid modeling engine to extract three-dimensional uncut chip geometry, from which the two-dimensional cross section is obtained via Delaunay triangulation. Cutting velocities along discretized cutter edges are calculated and used to determine the effective rake and oblique angles. Then, force predictions are made using the oblique cutting model and validated using measurements from power skiving trials performed on a DMG MORI NT5400DCG mill-turn machine.     

一种城市道路照明的节能措施

着重讨论次干道及以下道路照明的节能问题,通过接在路灯回路里的时间继电器和中间继电器的控制器完成隔灯亮灯的功能,并和增加电力电缆控制隔灯亮灭的方法进行了技术经济比较,证明取得了较好的节能效果,最后还分析了这种方法存在的问题。     

同源异构--科尔沁右翼前旗地区当代乡土住宅的自发性建造的研究

城郊乡村的乡土景观面临"重写",而其间的乡土住宅正在经历一种自发的转型,其"自组织"的生成机制值得研究。本文以科尔沁右翼前旗地区的若干村镇的当代乡土住宅为样本,从组织机制的角度,分析其受控过程,分别从基因、共享、突变和蔓延四个方面展开分析,总结该地区的当代乡土住宅从无序向有序的演变过程。     

景观规划与法规体系研究

本文阐述了城市景观规划的目的、规划对象的特征、景观法规的功能,以及景观规划法规体系的存在与构成。指出了我国城市景观建设的问题在于规划技术体系和行政管理体制不完善、法规体系不健全。最后通过分析国外景观建设的经验,论证了完善我国景观规划与法规体系的重要性和途径。     

湖北蒲圻2×300MW电厂锅炉汽包吊装施工

湖北蒲圻电厂2×300MW机组,汽包外形直径φ2.033m,长22.500m,重167t,提升过程中汽包需倾斜32°以上,方可顺利通过各层横梁。本文通过分析吊装过程中汽包的受力状态,论述了液压提升技术在汽包倾斜吊装中的可行性,对汽包吊装具有普遍意义。