Decomposing apparent power and losses in distribution systems with nonlinear loads

The definition of reactive power for non-sinusoidal conditions is a controversial issue. The mathematical treatment of nonlinear loads in power systems is also unsettled. This paper starts with the decomposing of apparent power in,the cases of linear and nonlinear loads. When harmonics are present, apparent power is composed of active power, reactive power, and disturbed reactive power. Linear element can be defined as the element without disturbed reactive power. This definition is based on a practical engineering concept which can separate the contribution from the apparent power into utility-duty part and custom-duty part. The field investigation of home-used facilities was conducted. Also the data acquisition in the 0.4 kV distribution systems was completed. Moreover, the loss increase due to the nonlinear loads was estimated. Nonlinear loads can be a dominant effect with respect to reactive power and power factor. Field data from a number of nonlinear load types indicate that the disturbed reactive power can cause significant losses in utility supply systems.     

在示范院校建设中培养核心竞争力——文化理念谈隅

文化理念是学院核心竞争力的载体,是学院核心价值观的具体体现。在示范院校建设新时期,构建以人为本、忧患意识、创新意识为特征的新的学院文化理念,能够使教职工在工作中自发地释放教学热情和创新灵感,不断提高学院的核心竞争力。     

历史时期熊类认识及利用情况初探

熊是利用价值较大的动物,毛皮可用,肉、掌能食,胆、脂作药,幼小的熊崽,易于驯养。千百年来人们对熊的认识逐渐加深,并对其进行了有效的利用。历史动物研究是历史地理学的一个重要组成部分,以熊为例探究历史时期人们对熊类的认识和利用情况,初步探讨导致历史环境变迁的人类需求这一驱动力因素。     

危机事件中互联网"圈子"用户的共情传播机制研究 ——基于情感共情和认知共情双过程探索

互联网"圈子"的形成,加速了危机事件传播的速度与效率,使得信息流动更加快速、便利.但危机事件的全面渗透造成了公众心理和情绪的快速形成、更替与变迁,人们开始正视危机事件中关于"理性"与"感性"的辩证思考.基于此,研究通过危机事件、共情传播以及传播效应的相互关联分析,提出了规律性假设,并应用实证分析进行了具体事例的认知探索.结果表明,危机事件中互联网"圈子"用户的共情传播机制呈情感共情和认知共情双过程表现,且各假设成立.同时,研究又根据实证中提取的要素特征和传播路径,构建了共情传播要素评价体系,勾勒了危机事件中互联网"圈子"用户的共情传播演化机制与发展轨迹,讨论了共情传播路径探索新思路.     

秦始皇兵马俑博物馆室内含硫颗粒物的SEM-EDX研究

本文对秦始皇兵马俑博物馆室内采集的长短期降尘、大气悬浮颗粒物和彩绘漆层进行了SEM-EDX研究，在大气悬浮颗粒、短期和长期降尘中，含硫颗粒的粒径分别为0.9～22.8μm、1.0～29.0μm和1.2～37.7μm，多为石膏与粘土或石英以内部混合的状态存在。降尘中的附着型絮状硫酸钙多于大气悬浮颗粒物中，显示降尘和大气中的二氧化硫发生了累进的化学反应。彩绘漆层表面的坑和裂隙附近观察到原位生长的硫酸钙晶体，显示漆层材料或降尘颗粒物与大气二氧化硫之间的酸化学反应，可能是彩绘漆层表面受侵蚀形成微小坑和裂隙的原因之一。     

简单网络管理协议初探

对于基于IP的网络和互联网络的管理而言，简单网管协议（SNMP）是应用最广泛的协议。SNMPv1作为原先的版本被很广泛地应用，SNMPv2版本添加了功能，但并未强调其 安全性限制。目前，SNMPv3正在努力的研究过程中，它将增加强大的保密和认证特性。本文将介绍SNMP, 并且对管理信息如何表现以及协议的功能性进行讨论。     

彩电示教板中的"地"

探讨了彩电示教板电路中“地”的特点、分类及作用，对学生和维修爱好顺利安全地解决故障及疑难问题．提供了参考依据。     

马克思主义经济学范式的特征——兼评后现代主义的马克思主义经济学范式

范式概念的引入无疑有利于马克思主义经济学的清晰界定,表明什么是马克思主义经济学以及马克思主义经济学完善和发展的内在机制和动力.后现代主义的马克思主义经济学否定历史唯物主义方法论和劳动价值论这个马克思主义经济学分析的逻辑起点,显然是对马克思主义经济学范式"硬核"的背弃.     

Phenol Tert-Butylation Catalyzed by Zeolite H-Mordenite

Para-tert-butyl phenol (p-TBP) and 2,4-di-tert-butyl phenol ( 2,4-DTBP) are wi.dely used for the preparation of antioxidants. Zeolite catalysts showed good performance for the synthesis of p-TBP and 2,4-DTBP. In this work, zeolite H-mordenite (HM) catalyst was prepared and the alkylation of phenol with tert-butyl alcohol over zeolite HM catalyst was investigated at different reaction conditions. It is found that increasing temperature enhances the selectivity to p-TBP and the optimum reaction temperature for phenol conversion is 438 K. Increasing flow rate decreases phenol conversion apparently while the selectivity to p-TBP has a little increase. The suitable tert-butyl alcohol/phenol molar ratio is 2. Lower alcohol/phenol molar ratios are beneficial to p-TBP while higher ones are helpful for producing 2,4-DTBP.     

Modeling Self-Regulation as a Process Usinga Multiple Time-Scale Multiphase Latent Basis Growth Model

Measurement burst designs, wherein individuals are measured intensively during multiple periods (i.e., bursts), have created new opportunities for studying change at multiple time scales. This article develops a model that might be useful in situations where the functional form of short-term change is unknown, might consist of multiple phases, and might change over the long term. Specifically, we combine measurement of intraindividual entropy, a latent basis growth model, a multiphase growth model, and a growth model with covariates into a unified framework that could help accommodate the complexity of patterns that emerge in multiple time-scale categorical data streams. Empirical data from a longitudinal study of young children’s behavior during laboratory tasks designed to induce frustration are used to illustrate the utility of the proposed model for simultaneously describing intratask (short-term) change in self-regulation and developmental (long-term) shifts in intratask change.