继电保护在农村1OkV电网线路的应用

继电保护技术随着电力系统的发展而不断发展,它为电力系统运行提供了安全保障,是提高供电质量、减少事故损失最直接有效的手段.目前我国农村电网发展现状不容乐观,继电保护技术的引入为农村电网发展注入了新的活力.文中主要分析了继电保护技术在农村10kV电网线路中的应用及其应注意的问题等,以促进我国农村电网健康的发展.     

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。     

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.     

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.     

环境规制、能源消费结构与雾霾——基于省际面板数据的实证检验

采用我国30省(市、区)2003—2012年面板数据,分析环境规制强度、能源消费结构与雾霾之间的关系。首先,以PM10浓度指标进行聚类,把30省(市、区)划分为高、中、轻三大污染地区。其次,面板单位根检验结果显示各变量是一阶单整I(1);Pedroni和Kao协整检验表明变量之间存在协整关系;FMOLS回归发现,全国总体环境规制强度与PM10浓度呈反方向变动,能源消费结构与PM10浓度呈同方向变动;高污染地区能源消费结构对PM10浓度产生正的影响,中、轻污染地区环境规制强度对PM10浓度产生负的影响。最后,提出了使用法律、经济手段加强环境规制,降低煤炭消耗比例、发展清洁能源等建议。     

Food price increases and net food importing countries: lessons from the recent past

Recent increases in food and other commodity prices have highlighted concerns that many poor countries are net food importers and higher food prices would worsen their trade balances. In this article, we analyze the changes in food trade balances associated with the 32% increase in food prices from 2000/2001 to 2004/2005. We find a small deterioration in food trade balances of low‐income countries and an improvement in middle‐income countries. The deterioration is most severe for countries in conflict and small island states, so attention should be placed first on these countries and on a few very‐low‐income countries that are also vulnerable. Because low‐income countries as a group had much lower agricultural GDP growth rates than middle‐income countries, the answers to food vulnerability in low‐income countries should probably be addressed within the context of incentives for agricultural production.     

Reassessing marketing boards as hybrid arrangements: evidence from Canadian experiences

In this article, we reassess the role of marketing boards and similar arrangements that have played an important role in numerous agro‐food sectors of developed countries over almost a century. Referring to transaction cost economics and to more recent contributions on the allocation of decision and property rights, we interpret these arrangements as hybrid modes of governance. We hypothesize that uncertainty is the leading force pushing toward these organizational solutions and we explore forms of uncertainty at stake and their impact in shaping various types of hybrids. We also explore the role of institutional embeddedness in providing marketing boards and the like their legitimacy. Using numerous examples from Canadian marketing boards, we discuss the benefits and point out flaws of these arrangements. We conclude on the need to assess comparatively the role of these solutions with respect to, for example, a system of bilateral contracts.     

The regional wage gap in the Spanish hospitality sector based on a gender perspective

In this work we estimate human capital returns in the Spanish hospitality sector using an expanded version of the Mincer wage equation (1974). In addition, wage differences in the main tourist regions are quantified using the wage decomposition of Oaxaca (1973) and Blinder (1973) from a gender perspective. Using data from the 2006 Spanish Wage Structure Survey (Encuesta de Estructura Salarial), all the regions under analysis show lower education returns in the hospitality sector when compared to other private services. The same results are found for the other human capital variables used. There are significant differences in education returns between regions, especially in Catalonia and the Canary Islands. The main wage gap in the Canary Islands and the Madrid region is due to differences in returns in the observed variables, whereas in other regions most of the differences are due to the resources allocated. Furthermore, gender wage differences are found in all the regions. The largest estimated wage gap between men and women occurs in the Balearic Islands followed by Catalonia and the Community of Valencia. In contrast, equality between genders is greater in the Community of Madrid.