应对风电接入的分级控制策略研究

针对由风功率的随机性和波动性导致电网侧电压稳定性问题,提出基于改进五区图的分级控制策略。通过以改进五区图作为动作判据并缩小其"0"区范围,在多种控制方式组合中采用经典遗传算法选取最优组合作为上级控制策略,将电网侧系统电压调节并保持在限制值内;对于风功率预测值和实际值的偏差可能导致的电压越限问题,下级控制策略采取以改进五区图中动态无功补偿装置的动作区作为动作判据制定出相应的控制方式,做到快速跟踪,实时响应,最后经仿真试验验证了控制策略的实用性和可行性。     

氧化锌避雷器在线监测方法的研究

基波电压产生的基波阻性电流ir和三次阻性电流i3r可以反应MOA的运行状况。改进的容性电流补偿法可有效去除全电流中的容性电流,但全电流中仍存在谐波电压产生的阻性电流,影响了ir和i3r的提取精度,特别是i3r的误差较大。为解决此问题,在改进补偿法的基础上,提出了改进容性电流补偿法的修正方法,借助于一等效的线性电阻补偿了部分谐波电压产生的阻性电流,从而减小了谐波电压引起的误差,提高了i3r的提取精度。仿真分析表明,修正后i3r的误差减小了一半,验证了此修正方法的有效性,也提高了根据ir和i3r判断MOA故障方法的准确性。     

通信建设项目评价模型研究

为提高项目决策的科学性和准确性,本文提出采用TOPSIS模型进行多目标决策,同时建立科学的指标体系和权重分配体系,解决项目多方案决策的难题。     

基于改进BOF算法的压板状态识别方法研究

随着电网规模的扩张以及二次技术的发展,二次屏柜的压板数量急剧上升.二次压板一旦出现保护误动或拒动,将严重威胁到电网、设备与人身安全.设计了一种基于改进图像检索算法的继电保护压板状态识别系统对压板退投状态进行识别.首先,对压板图像利用背景差分法及光流法进行前景提取;然后,采用图片增强处理、边缘检测等一系列技术识别开关的投...     

L2–L∞ fuzzy control for Markov jump systems with neutral time-delays

The L₂–L_∞ fuzzy control problem is considered for nonlinear stochastic Markov jump systems with neutral time-delays. By means of Takagi–Sugeno fuzzy models, the fuzzy controller systems and the overall closed-loop fuzzy dynamics are constructed. A sufficient condition is firstly established on the stochastic stability using stochastic Lyapunov–Krasovskii functional. Then in terms of linear matrix inequalities techniques, the sufficient conditions on the existence of mode-dependent state feedback L₂–L_∞ fuzzy controller are presented and proved respectively for constant and time varying case. Finally, the design problems are formulated as optimization algorithms. Simulation results are exploited to illustrate the effectiveness of the developed techniques.     

Hybrid charge control for stick-slip piezoelectric actuators

The article describes an analog electronic circuit for driving stick-slip piezoelectric linear actuators. The task for the amplifier is to provide a high-voltage asymmetric sawtooth-like signal and feed it into a capacitive load. Generation of excessive heat must be avoided while maximizing the slew rate. In order to guarantee a steady translation, the hysteretic behaviour of the piezoelectric material must be compensated. Combination of a charge control scheme with switching is proposed as an efficient solution. Laboratory experiments confirm the superiority of this tailored solution over other existing techniques based on versatile linear voltage amplifiers.     

Regulation of memory accuracy with multiple answers: The plurality option.

We report two experiments that investigated the regulation of memory accuracy with a new regulatory mechanism: the plurality option. This mechanism is closely related to the grain-size option but involves control over the number of alternatives contained in an answer rather than the quantitative boundaries of a single answer. Participants were presented with a slideshow depicting a robbery (Experiment 1) or a murder (Experiment 2), and their memory was tested with five-alternative multiple-choice questions. For each question, participants were asked to generate two answers: a single answer consisting of one alternative and a plural answer consisting of the single answer and two other alternatives. Each answer was rated for confidence (Experiment 1) or for the likelihood of being correct (Experiment 2), and one of the answers was selected for reporting. Results showed that participants used the plurality option to regulate accuracy, selecting single answers when their accuracy and confidence were high, but opting for plural answers when they were low. Although accuracy was higher for selected plural than for selected single answers, the opposite pattern was evident for confidence or likelihood ratings. This dissociation between confidence and accuracy for selected answers was the result of marked overconfidence in single answers coupled with underconfidence in plural answers. We hypothesize that these results can be attributed to overly dichotomous metacognitive beliefs about personal knowledge states that cause subjective confidence to be extreme. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Deficits in emotion-regulation skills predict alcohol use during and after cognitive–behavioral therapy for alcohol dependence.

Objective: As emotion regulation is widely considered to be a primary motive in the misuse of alcohol, our aim in the study was to investigate whether deficits in adaptive emotion-regulation skills maintain alcohol dependence (AD). Method: A prospective study investigated whether emotion-regulation skills were associated with AD and whether these skills predicted alcohol use during and after treatment for AD. Participants were 116 individuals treated for AD with cognitive–behavioral therapy. Emotion regulation and severity of AD symptoms were assessed by self-report. Alcohol use during treatment was assessed by Breathalyzer and urine analysis for ethyl glucuronide; alcohol use during the 3-month follow-up interval was assessed by self-report. Results: Pretreatment emotion-regulation skills predicted alcohol use during treatment, and posttreatment emotion-regulation skills predicted alcohol use at follow-up, even when controlling for other predictors potentially related to emotion regulation. Among a broad range of specific emotion-regulation skills, the ability to tolerate negative emotions was the only skill that negatively predicted subsequent alcohol consumption when controlling for the other skills. Individuals in the AD sample reported significantly larger deficits in emotion-regulation skills than did those in a nonclinical control sample but significantly less than did those in a sample of individuals exclusively meeting criteria for major depressive disorder. Conclusions: Enhancement of general emotion-regulation skills, especially the ability to tolerate negative emotions, appears to be an important target in the treatment of AD. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

基于加气站槽车调度的模型建立与算法研究

通过对CNG的发展形势介绍,深入到要研究的具体问题——槽车调度,槽车调度就是加气站母站向子站调度发送槽车。匈牙利算法是用到线性规划上解决最优化最优解的问题。考虑到槽车调度优化的问题的特殊性,因此在匈牙利算法的思想基础上,提出了最大差值法。此方法能更高效率地运算出最优解。     

The effects of pause software on the temporal characteristics of computer use

The study investigated the natural work–pause pattern of computer users and the possible effects of imposing pause regimes on this pattern. Hereto, the precise timing of computer events was recorded across a large number of days. It was found that the distribution of the pause durations was extremely skewed and that pauses with twice the duration are twice less likely to occur. The effects of imposing pause regimes were studied by performing a simulation of commercially available pause software. It was found that depending on the duration of the introduced pause, the software added 25–57% of the pauses taken naturally. Analysis of the timing of the introduced pauses revealed that a large number of spontaneous pauses were taken close to the inserted pause. Considering the disappointing results of studies investigating the effects of introducing (active) pauses during computer work, this study has cast doubt on the usefulness of introducing short duration pauses.