10kV配电线路接地故障原因及有效预防措施

配电线路是电网的基础设施,其故障发生频率较高并且涉及的原因也比较广泛。文章主要介绍了10 kV配电线路中单相接地的故障类型及发生原因,并阐述了一定的预防措施和处理方法以及新技术和新设备在该方面的应用。     

10kV开关柜电气故障分析与处理

10 kV开关柜在运行中经常会出现电气故障,造成经济上的严重损失,为了保证设备安全运作,降低故障所造成的损害,要有效地做好开关柜电气故障的检测和预防。文章针对10 kV开关柜出现的电气故障,探讨故障出现的原因并给予了相关的处理策略。     

110～220kV输电线路设计要点分析

社会经济的发展促进了电力行业的改革进步,早期的输电线路已经难以满足高负荷的用电需求。110～220 kV输电线路是电力系统中重要的电力传输装置,对我国现代社会供电运行有着很大的影响。在设计输电线路时应该考虑到多个方面的问题,文章从安全性能、在线监测、杆塔施工等方面进行设计分析。     

Uncertain spatial demand and price flexibility: A state space approach to duopoly

Sufficient conditions for a unique price equilibrium, in terms of the uncertainty distribution and the state contingent consumer distributions, are given for spatial duopoly. Also considered are efficiency and endogenous locations for the symmetric case and comparative statics on price flexibility.     

The nonlinear effects of expected and unexpected components of monetary policy on the dynamics of REIT returns

This paper examines empirically whether the expected and unexpected components of monetary policy have nonlinear impacts on the dynamics of REIT returns. Empirical results find the nonlinear response of REIT returns to expected and unexpected components of monetary policy. The unexpected component of monetary policy plays a more prominent role in influencing REIT returns than does the expected component of monetary policy. Specifically, unexpected contractionary monetary policy has a significantly adverse impact on REIT returns, and the adverse effect in a bust market is stronger than in a boom market. In addition, the unexpected monetary policy will also affect the boom-bust dynamics of REIT returns through its effect on the time-varying transition probability matrix. The tightening of the expected and unexpected components of monetary policy will enhance the probability that the REIT market will stay in the bust regime.     

Agriculture production versus biodiversity protection: The impact of North-South unconditional transfers

The purpose of this paper is to explore whether international income transfers can improve or worsen the global level of biodiversity and global social welfare by changing the relative contributions to biodiversity protection and to agricultural production. Because of the public good nature of biodiversity, Warr's neutrality theorem suggests that such transfers may have no effects at all (Warr, 1983). A model is developed, based on the simplifying assumption that northern countries have little biodiversity whereas southern countries are endowed with natural capital in the form of (generally unspoilt) biodiversity-rich land. Southern countries allocate optimally land and capital to two competing productive activities, agriculture and eco-tourism. When transfers are organized from the North to the South, we show that Warr's neutrality theorem collapses. Transfers can either reduce or increase the natural capital in the South, depending on some empirically verifiable hypotheses concerning the characteristics of the eco-tourism and agricultural production functions. In addition, we demonstrate that welfare improvements can be obtained even with reductions in the level of biodiversity.     

An updated ranking of academic journals in economics

Abstract We conduct an update of the ranking of economic journals by Kalaitzidakis, Mamuneas, and Stengos (2003) . However, our present study differs methodologically from that earlier study in an important dimension. We use a rolling window of years between 2003 and 2008, for each year counting the number of citations of articles published in the previous 10 years. This allows us to obtain a smoother longer view of the evolution of rankings in the period under consideration and avoid the inherent randomness that may exist at any particular year, because of new entrants.     

浅谈“六统一”的设计及应用

目前江苏省正在推广按照＂六统一＂原则提出的典型设计,本文主要探讨了按照＂六统一＂设计后的220kV线路保护与未按原则之前的不同之处,选取三个问题进行讨论,包括线路电压互感器的普遍使用,两套保护的重合闸配合,母线保护的失灵启动回路等,提出一些在变电二次工作中会遇到的问题,供现场的施工人员参考和借鉴。     

MACROECONOMIC UNCERTAINTY AND CONDITIONAL STOCK MARKET VOLATILITY IN SOUTH AFRICA*

This paper analyses how systematic risk emanating from the macroeconomy is transmitted into stock market volatility using augmented autoregressive Generalised Autoregressive Conditional Heteroscedastic (AR‐GARCH) and vector autoregression (VAR) models. Also examined is whether the relationship between the two is bidirectional. By imposing dummies for the 1997‐1998 Asian and the 2007‐2009 sub‐prime financial crises, the study further analyses whether financial crises affect the relationship between macroeconomic uncertainty and stock market volatility. The findings show that macroeconomic uncertainty significantly influences stock market volatility. Although volatilities in inflation, the gold price and the oil price seem to play a role, it is found that volatility in short‐term interest rates and exchange rates are the most important, suggesting that South African domestic financial markets are increasingly becoming interdependent. Finally, the results show that financial crises increase volatility in the stock market and in most macroeconomic variables, and, by so doing, strengthen the effects of changes in macroeconomic variables on the stock market.     

Impact of copula choice on the modeling of crop yield basis risk

A number of problems in agricultural economics involve modeling joint distributions for which the assumption of multivariate normality may not be warranted. Yet, very little work has been conducted evaluating competing methods for modeling joint dependence. We develop a simulation framework to evaluate the bias and efficiency impacts of copula choice in the context of evaluating county‐to‐farm basis risk. The results suggest significant differences in performance across various copulas and approaches. The findings have important implications for risk analysis, insurance, and policy modeling problems in agriculture regarding the selection of method to model dependence among random variables.