多电压等级配电网最优容载比的计算方法

在综合考虑配电网容载比选取的技术性和经济性基础上,建立求解多电压等级配电网最优容载比的优化模型。技术上主要基于《城市电力网规划设计导则》中的容载比计算公式,并对其中的负荷分散系数计算方法提出改进;经济上主要基于容载比的经济性评价体系,提出了变电站的建造成本、机会成本、维护成本、电能损耗成本、资源浪费成本以及残值的计算方法。采用离散粒子群优化算法求解所建立的容载比优化模型,以华东某地区局部配电网为例进行分析计算,说明本文所提出的模型及算法的有效性。

应用高最优容限模型分析北美大停电机理若干问题的探讨

在回顾标准H.O.T.模型建立过程的基础上,完善模型参数的估计方法.采用1984-1999年美国西部电网（W.S.C.C.）和北美东北电网（N.P.C.C.）的停电统计数据,结合标准H.O.T.模型,进行对比性分析.分析结果与W.S.C.C.的实际数据吻合,但与N.P.C.C.的实际数据有一定偏离.为此,提出了模型参数选择方法和模型与实际电网对应技术,认为标准的H.O.T.模型需要进一步完善,以满足实际运行数据的分析,并提出应用H.O.T.模型分析大停电事故的一些思路.

试析汉文帝优容诸侯王的真正原因

汉文帝刘恒在位23年,他对诸侯王优容有加,主要有汉初的社会经济和他本人的个性特点两大方面的原因。也就是说,汉文帝即位初期的政治经济背景以及汉文帝本人的个性特点造成了他对诸侯王的优容甚至纵容,使得诸侯实力得以逐渐增强,终于威胁到中央集权。

基于逆变器过载损失的双面组件光伏电站最优容配比分析

以某个实际采用双面光伏组件的光伏电站(下文简称为“双面组件光伏电站”)为例,本文对比了不同容配比下双面组件光伏电站中逆变器的实际过载损失和模拟过载损失,结果发现:逆变器的模拟过载损失比其实际过载损失小,这会导致通过模拟光伏电站发电量得到的光伏电站最优容配比与实际情况存在偏差。因此,通过采用最小二乘法多项式曲线拟合和数据映射法,利用不同容配比下双面组件光伏电站的实际发电量损失数据校正模拟得到的发电量损失数据,并由此得到符合实际情况的双面组件光伏电站发电量推算值,最终通过校正后的发电量推算值获得与实际情况相符的双面组件光伏电站的最优容配比。

优容·征服·怀柔:唐初二帝经营东突厥战略述论

隋末唐初,东突厥再次崛起于蒙古草原,在此鼎革之际,俨然以"共主"的身份操纵北方政局。为了获得它的声援和支持,李渊父子主动向其输诚,并通过倾力交好,尊崇优容的方式,在满足其物资贪欲的同时,促使它成为大唐统一的推手。随着翦灭群雄,帝国开始追求"敌国"地位,从妥协、退让发展为对抗与征服。随后利用东突厥内部不可克服的矛盾,积极进行战争准备,一战而定北疆。此后大唐以开放的心态、恢弘的气度对待突厥的降人,并通过怀柔与安抚,推行"胡越一家"的国策,实现大唐皇帝与西北游牧民族君长"天可汗"合一。

做一个中国式的优容、睿智的班主任

班主任是学生的直接榜样,对于学生的成长起到了无声的示范作用,他的人格品质对于学生一生人格素养的形成至关重要。当学生学习成绩提升时,班主任如何坦然面对;而当学生学习成绩下降时,又将怎样做到心平气和。所以,身为班主任,我们应该具有优容、睿智的风范。

执着 灵性 优容——追忆黄曼君老师

2010年11月22日中午,黄曼君老师永远的离开了我们。24日,我们在武昌殡仪馆瞻仰他老人家的仪容,我感觉他除了眼睛闭着以外,脸上仍然同往日一样,明朗而灿烂。我送的挽联是:不是门生重我亲我鞭策我胜似导师敬您爱您想念您说起来,我和黄老师的缘分有些特别。我在华师的学业,是在京山分院完成的,大学期间,无缘结识黄老师。

宋真宗初年的政治生活

传统上人们对宋真宗误解较多,多把其与宋辽、宋夏议和的耻辱和大兴土木、东封西祀的活动联在一起,很少谈及其初年的政治生活,因此还原一个真实的政治生活方面的宋真宗,可以更加客观地看待其历史。

Optimal distributed resource allocation in a wireless sensor network for control systems

Wireless technology is applied increasingly in networked control systems. A new form of wireless network called wireless sensor network can bring control systems some advantages, such as flexibility and feasibility of network deployment at low costs, while it also raises some new challenges. First, the communication resources shared by all the control loops are limited. Second, the wireless and multi-hop character of sensor network makes the resources scheduling more difficult. Thus, how to effectively allocate the limited communication resources for those control loops is an important problem. In this paper, this problem is formulated as an optimal sampling frequency assignment problem, where the objective function is to maximize the utility of control systems, subject to channel capacity constraints. Then an iterative distributed algorithm based on local buffer information is proposed. Finally, the simulation results show that the proposed algorithm can effectively allocate the limited communication resource in a distributed way. It can achieve the optimal quality of the control system and adapt to the network load changes.

Multi-objective optimization of process based on resource capability

To improve the practicability, suitability and accuracy of the trade-off among time, cost and quality of a process, a method based on resource capability is introduced. Through analyzing the relationship between an activity and its’ supporting resource, the model trades off the time, cost and quality by changing intensity of labor or changing the types of supporting resource or units of labor of resource in a certain time respectively according to the different types of its’ supporting resources. Through contrasting this method with the model of unit time cost corresponding to different quality levels and inter-related linear programming model of time, cost and quality for process optimizing, it is shown that this model does not only cover the above two models but also can describe some conditions the above two models can not express. The method supports to select different function to optimize a process according to different types of its supporting resource.

Industrial and Agricultural Effects on Water Environment and Its Optimization in Heavily Polluted Area in Taihu Lake Basin, China

The deteriorating water quality in the Taihu Lake Basin has attracted widespread attention for many years, and is correlated with a sharp increase in the quantity of pollutant discharge such as agricultural fertilizers and industrial wastewater. In this study, several factors were selected for evaluating and regionalizing the water environmental capacity by ArcG1S spatial analysis, including geomor- phologic characteristics, water quality goals, water body accessibility, water-dilution channels, and current water quality. Then, the spa- tial optimization of agriculture and industry was adjusted through overlay analysis, based on the balance between industrial space and water environmental capacity. The results show that the water environmental capacity gradually decreases from the west to the east, in contrast, the pollution caused by industrial and agricultural clustering is distributes along Taihu Lake, Gehu Lake and urban districts. The analysis of the agricultural space focuses on optimizing key protected areas of the Taihu Lake Basin, and the shores of Gehu Lake, optimally adjusting the second protected areas of the Taihu Lake Basin, and generally adjusting the urban areas of Changzhou and Wuxi cities. The analysis of industrial space focuses on optimizing the downtowns of Changzhou and Wuxi cities, optimally adjusting key protected areas and second protected areas of the Taihu Lake Basin, and generally adjusting the south and southwest of Gehu Lake. Lastly, some schemes of industrial and agricultural layouts and policies for the direction of industrial and agricultural development were proposed, reflecting a correlation between industry and agriculture and the water environment.

Modeling and optimization of a multi-carrier renewable energy system for zero-energy consumption buildings

For the carbon-neutral,a multi-carrier renewable energy system(MRES),driven by the wind,solar and geothermal,was considered as an effective solution to mitigate CO2emissions and reduce energy usage in the building sector.A proper sizing method was essential for achieving the desired 100%renewable energy system of resources.This paper presented a bi-objective optimization formulation for sizing the MRES using a constrained genetic algorithm(GA)coupled with the loss of power supply probability(LPSP)method to achieve the minimal cost of the system and the reliability of the system to the load real time requirement.An optimization App has been developed in MATLAB environment to offer a user-friendly interface and output the optimized design parameters when given the load demand.A case study of a swimming pool building was used to demonstrate the process of the proposed design method.Compared to the conventional distributed energy system,the MRES is feasible with a lower annual total cost(ATC).Additionally,the ATC decreases as the power supply reliability of the renewable system decreases.There is a decrease of 24%of the annual total cost when the power supply probability is equal to 8%compared to the baseline case with 0%power supply probability.

Probabilistic Top-k Query:Model and Application on Web Traffic Analysis

Top-k ranking of websites according to traffic volume is important for Internet Service Providers(ISPs) to understand network status and optimize network resources. However, the ranking result always has a big deviation with actual rank for the existence of unknown web traffic, which cannot be identified accurately under current techniques. In this paper, we introduce a novel method to approximate the actual rank. This method associates unknown web traffic with websites according to statistical probabilities. Then, we construct a probabilistic top-k query model to rank websites. We conduct several experiments by using real HTTP traffic traces collected from a commercial ISP covering an entire city in northern China. Experimental results show that the proposed techniques can reduce the deviation existing between the ground truth and the ranking results vastly. In addition, we find that the websites providing video service have higher ratio of unknown IP as well as higher ratio of unknown traffic than the websites providing text web page service. Specifically, we find that the top-3 video websites have more than 90% of unknown web traffic. All these findings are helpful for ISPs understanding network status and deploying Content Distributed Network(CDN).

Multi-objective capacity allocation optimization method of photovoltaic EV charging station considering V2G

Large-scale electric vehicles(EVs) connected to the micro grid would cause many problems. In this paper, with the consideration of vehicle to grid(V2 G), two charging and discharging load modes of EVs were constructed. One was the disorderly charging and discharging mode based on travel habits, and the other was the orderly charging and discharging mode based on time-of-use(TOU) price;Monte Carlo method was used to verify the case. The scheme of the capacity optimization of photovoltaic charging station under two different charging and discharging modes with V2 G was proposed. The mathematical models of the objective function with the maximization of energy efficiency, the minimization of the investment and the operation cost of the charging system were established. The range of decision variables, constraints of the requirements of the power balance and the strategy of energy exchange were given. NSGA-Ⅱ and NSGA-SA algorithm were used to verify the cases, respectively. In both algorithms, by comparing with the simulation results of the two different modes, it shows that the orderly charging and discharging mode with V2 G is obviously better than the disorderly charging and discharging mode in the aspects of alleviating the pressure of power grid, reducing system investment and improving energy efficiency.

Optimal design considering structural efficiency of compressed natural gas fuel storage vessels for automobiles

The shape and thickness of the dome were investigated with the aim of optimizing the type II CNG storage vessels by using a finite element analysis technique. The thickness of the liners and reinforcing materials was optimized based on the requirement of the cylinder and dome parts. In addition, the shape of the dome, which is most suitable for type lI CNG storage vessels, was proposed by a process of review and analysis of various existing shapes, and the minimum thickness was established in this sequence： metal liners, composite materials and dome parts. Therefore, the new proposed shape products give a mass reduction of 4.8 kg（5.1%）

Capacity Maximization Based Power Loading Analysis for Digital Channelized Satcom Systems

For digital channelized frequency division multiple access based satellite communication(SATCOM) systems,it is a challenging but critical issue to improve the transponder power and spectrum efficiency simultaneously under limited and non-linear high-power amplifier conditions.In this paper,different from the traditional link supportability designs aiming at minimizing the total transponder output power,a maximal sum Shannon capacity optimization objective is firstly raised subject to link supportability constraints.Furthermore,an efficient multilevel optimization(MO) algorithm is proposed to solve the considered optimization problem in the case of single link for each terminal.Moreover,in the case of multiple links for one terminal,an improved MO algorithm involving Golden section and discrete gradient searching procedures is proposed to optimize power allocation over all links.Finally,several numerical results are provided to demonstrate the effectiveness of our proposals.Comparison results show that,by the MO algorithm,not only all links' supportability can be guaranteed but also a larger sum capacity can be achieved with lower complexity.

Lifetime prediction for tantalum capacitors with multiple degradation measures and particle swarm optimization based grey model

A lifetime prediction method for high-reliability tantalum （Ta） capacitors was proposed, based on multiple degradation measures and grey model （GM）. For analyzing performance degradation data, a two-parameter model based on GM was developed. In order to improve the prediction accuracy of the two-parameter model, parameter selection based on particle swarm optimization （PSO） was used. Then, the new PSO-GM（1, 2, co） optimization model was constructed, which was validated experimentally by conducting an accelerated testing on the Ta capacitors. The experiments were conducted at three different stress levels of 85, 120, and 145℃. The results of two experiments were used in estimating the parameters. And the reliability of the Ta capacitors was estimated at the same stress conditions of the third experiment. The results indicate that the proposed method is valid and accurate.

Asymptotically Optimal and Admissible Empirical Bayes Estimation of Normal Parameter

Under square loss, this paper constructs the empirical Bayes（EB） estimation for the parameter of normal distribution which has both asymptotic optimality and admissibility. Moreover, the convergence rate of the EB estimation obtained is proved to be O（n^-1）.

Optimal transmission strategy for spatially correlated MIMO systems with channel statistical information

In real multiple-input multiple-output (MIMO) systems, the perfect channel state information (CSI) may be costly or impossible to acquire. But the channel statistical information can be considered relatively stationary during long-term transmission. The statistical information can be obtained at the receiver and fed back to the transmitter and do not require frequent update. By exploiting channel mean and covariance information at the transmitter simultaneously, this paper investigates the optimal trans- mission strategy for spatially correlated MIMO channels. An upper bound of ergodic capacity is derived and taken as the per- formance criterion. Simulation results are also given to show the performance improvement of the optimal transmission strategy.

Frame length optimization for multi-antenna downlink systems based on delay-bound violation probability constraints

A flame length optimization scheme is proposed for multi-antenna downlink systems to guarantee diverse delay- bound violation probability constraints. Due to the difficulties of extracting the quality of service （QoS） metrics from the conventional physical-layer channel models, the link-layer models named effective bandwidth and effective capacity are applied to statistically characterize the source traffic patterns and the queuing service dynamics. With these link-layer models, the source traffic process and the channel service process are mapped to certain QoS parameters. The packet delay-bound violation probability constraints are converted into minimum data rate constraints and the optimization problem is thus formulated into simultaneous inequalities. With the assumption of ergodic block-fading channels, the optimal frame lengths of single-user and multiuser systems are calculated respectively by numerical iterative methods. Theoretical analyses and simulation results show that the given delay-bound violation probability constraints are well satisfied with the optimal frame length.