Enhanced control of DFIG-used back-to-back PWM VSC under unbalanced grid voltage conditions

This paper presents a unified positive-and negative-sequence dual-dq dynamic model of wind-turbine driven doubly-fed induction generator(DFIG) under unbalanced grid voltage conditions. Strategies for enhanced control and operation of a DFIG-used back-to-back(BTB) PWM voltage source converter(VSC) are proposed. The modified control design for the grid-side converter in the stationary αβ frames diminishes the amplitude of DC-link voltage ripples of twice the grid frequency,and the two proposed control targets for the rotor-side converter are alternatively achieved,which,as a result,improve the fault-ride through(FRT) capability of the DFIG based wind power generation systems during unbalanced network supply. A complete unbalanced control scheme with both grid-and rotor-side converters included is designed. Finally,simulation was carried out on a 1.5 MW wind-turbine driven DFIG system and the validity of the developed unified model and the feasibility of the proposed control strategies are all confirmed by the simulated results.     

建设体育强国进程中体育场馆资源非均衡发展研究*

体育场馆资源的快速健康发展是建设体育强国的重要保障,近20年我国体育场馆资源建设成绩显著,然而长期存在城乡、行业系统、地区之间的发展差异依然存在.运用非均衡发展理论指导我国体育场馆资源的未来发展更具有合理性和现实指导意义,开放行业系统内体育场馆资源,最大限度发挥体育场馆资源的公共属性;在城乡和地区之间有计划的发展高、中、低档次相结合的体育场馆设施,形成中心城市——中小城镇——乡村的梯次发展布局,满足不同区域人们的体育参与需求.在市场和政府的共同作用下实现体育场馆资源的最优化配置.     

吉尔吉斯斯坦共和国不平衡双语制研究

吉尔吉斯斯坦继承了苏维埃时期的不平衡双语制,独立后政策制定者试图促使其向平衡的双语制转变,但没有成功。文章探讨了吉尔吉斯斯坦共和国不平衡双语制的背景、内容和影响因素。     

非均衡发展战略视角下我国冰雪体育产业发展对策研究

以我国冰雪体育产业发展为研究对象,以冰雪体育产业非均衡发展战略为主线,立足理清我国冰雪体育产业发展的现状及存在的主要问题,在满足现有的社会效应和创造更大的经济效益的基础上,为我国冰雪体育产业健康发展献计献策。研究结果显示,我国冰雪体育产业发展要执行非均衡发展战略,应分为国家战略、区域战略和企业战略来进行。     

基于马氏距离的模糊支持向量机及其在用户行为识别中的应用研究

基于支持向量机的分类原理,对具有显著不平衡性的用户行为数据进行分析,旨在探索一种利用用户浏览商品网页时的行为特征,识别用户关于商品品牌购买偏好的方法。文章提出一种基于马氏距离的高维空间类中心隶属度构建方法,将该方法与支持向量机和基于欧式距离的高维空间类中心隶属度的模糊支持向量机进行比较,通过一组对比实验,证明该方法用于对用户行为偏好识别的有效性和优越性。     

在爱中涅槃在俗世中老去--方方中篇小说《水随天去》读后

少年水下纯洁的骑士爱情的毁灭,再现了方方小说的爱情错位模式,也展现了爱情在俗世欲望下的无奈与溃败,是方方对情爱价值的绝望及坚守。     

低压电网中的单项负载及其对电网运行特性的影响

针对低压电网中常见的线路末端电压过低及网络损耗过大等现象，本文比较了三相负载和单相负载的运行特性，分析计算表明单相负载的大量接入是造成低压电网不经济、不安全现象的主要因素.     

论高校体育信息化非均衡发展策略

通过对高校体育信息化的现状及原因分析,认为高校体育信息化需要采取非均衡发展策略。高校体育信息化非均衡发展策略包括:学校间非均衡发展、结构性非均衡发展和阶段非均衡发展。高校体育信息化非均衡发展策略的最终目的是高校体育信息化的均衡发展。     

Nonparametric functional analysis under joint estimation with applications to identifying highly cited papers

This article introduces a nonparametric methodology combining the strengths of binary regression and latent variable formulations, while overcoming their disadvantages. The mathematical results are implemented through a novel Bayesian Hierarchical estimation methodology called Latent Adaptive Hierarchical Expectation Maximization Like algorithm. Requiring minimal assumptions, it extends extant methodologies, and in simulation studies gives better prediction and inference performances for asymmetric data generating processes. A new classification statistic, called Adjusted Receiver Operating Curve Statistic is also introduced. Utilizing it we demonstrate better overall model fit, inference and prediction performance of the proposed methodology over widely used existing methods in the sciences. In addition, the methodology can be used to perform model diagnostics for any model specification. This is a highly useful result, and it extends existing work for categorical model diagnostics broadly across the sciences. Furthermore, the mathematical results also highlight important new findings regarding the interplay of statistical significance and scientific significance. Finally, the methodology is applied to identifying highly-cited papers in the social sciences in a joint estimation framework. The results indicate that the methodology outperforms widely used existing artificial intelligence and machine learning models with very few Monte Carlo iterations. In Scientometric application, it finds Journal Impact Factor to be more important than Keyword Popularity parameters for explaining citation outcomes in select social science fields. It further finds that the percentage change in Published Popularity may also help to explain citation outcomes in the field. The findings appear to be new to the Scientometric field.     

浅析两德统一模式形成的深层原因

两德统一是二战以来最重大的国际政治事件之一.本文从两德经济实力差距、两极失衡的国际政治局势、西欧的历史文化传统等方面入手,分析了两德统一的深层原因及对我国的启示.