954 resultados para Trends and Concepts on PV
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This paper presents a simple mathematical model to estimate shading losses on PV arrays. The model is applied directly to power calculations, without the need to consider the whole current–voltage curve. This allows the model to be used with common yield estimation software. The model takes into account both the shaded fraction of the array area and the number of blocks (a group of solar cells protected by a bypass diode) affected by shade. The results of an experimental testing campaign on several shaded PV arrays to check the validity of model are also reported.
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This paper presents the impact of non-homogeneous deposits of dust on the performance of a PV array. The observations have been made in a 2-MW PV park in the southeast region of Spain. The results are that inhomogeneous dust leads to more significant consequences than the mere short-circuit current reduction resulting from transmittance losses. In particular, when the affected PV modules are part of a string together with other cleaned (or less dusty) ones, operation voltage losses arise. These voltage losses can be several times larger than the short-circuit ones, leading to power losses that can be much larger than what measurements suggest when the PV modules are considered separately. Significant hot-spot phenomena can also arise leading to cells exhibiting temperature differences of more than 20 degrees and thus representing a threat to the PV modules' lifetime.
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This paper is a review of recent trends in United States expenditures on research and development (R&D). Real expenditures by both the government and the private sector increased rapidly between the mid-1970s and the mid-1980s, and have since leveled off. This is true of both overall expenditures and expenditures on basic research, as well as funding of academic research. Preliminary estimates indicate that about $170 billion was spent on R&D in the United States in 1995, with ≈60% of that funding coming from the private sector and about 35% from the federal government. In comparison to other countries, we have historically spent more on R&D relative to our economy than other advanced economies, but this advantage appears to be disappearing. If defense-related R&D is excluded, our expenditures relative to the size of the economy are considerably smaller than those of other similar economies.
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This paper reviews food (especially cereal) production trends and prospects for the world and its main regions. Despite fears to the contrary, in recent years we have seen continued progress toward better methods of feeding humanity. Sub-Saharan Africa is the sole major exception. Looking to the future, this paper argues that the continuation of recent cereal yield trends should be sufficient to cope with most of the demographically driven expansion of cereal demand that will occur until the year 2025. However, because of an increasing degree of mismatch between the expansion of regional demand and the potential for supply, there will be a major expansion of world cereal (and noncereal food) trade. Other consequences for global agriculture arising from demographic growth include the need to use water much more efficiently and an even greater dependence on nitrogen fertilizers (e.g., South Asia). Farming everywhere will depend more on information-intensive agricultural management procedures. Moreover, despite continued general progress, there still will be a significant number of undernourished people in 2025. Signs of heightened harvest variability, especially in North America, are of serious concern. Thus, although future general food trends are likely to be positive, in some respects we also could be entering a more volatile world.
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Spain’s immigrant population has increased 380 % in the last decade, accounting for 13.1 % of the total population. This fact has led her to become during 2009 the eighth recipient country of international immigrants in the world. The aim of this article is to describe the evolution of mortality and the main causes of death among the Spanish-born and foreign-born populations residing in Spain between 1999 and 2008. Age-standardised mortality rates (ASRs), average age and comparative mortality ratios among foreign-born and Spanish-born populations residing in Spain were computed for every year and sub-period by sex, cause of death and place of birth as well as by the ASR percentage change. During 1999–2008 the ASR showed a progressive decrease in the risk of death in the Spanish-born population (−17.8 % for men and −16.6 % for women) as well as in the foreign-born one (−45.9 % for men and −35.7 % for women). ASR also showed a progressive decrease for practically all the causes of death, in both populations. It has been observed that the risk of death due to neoplasms and respiratory diseases among immigrants is lower than that of their Spanish-born counterparts, but risk due to external causes is higher. Places of birth with the greater decreases are Northern Europe, Eastern Europe, Western Europe, Southern Europe, and Latin America and the Caribbean. The research shows the differences in the reduction of death risk between Spanish-born and immigrant inhabitants between 1999 and 2008. These results could contribute to the ability of central and local governments to create effective health policy. Further research is necessary to examine changes in mortality trends among immigrant populations as a consequence of the economic crisis and the reforms in the Spanish health system. Spanish data sources should incorporate into their records information that enables them to find out the immigrant duration of permanence and the possible impact of this on mortality indicators.
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From the Introduction. The Treaty on European Union, also known as the Treaty of Maastricht or the Maastricht Treaty, created the European Union (EU) from the existing European Economic Community (EEC.) It was signed by the member states on February 7, 1992, and entered into force on November 1, 1993.1 Among its many innovations was the creation of European citizenship, which would be granted to any person who was a citizen of an EU member state. Citizenship, however, is intertwined with immigration, which the Treaty also attempted to address. Policy on visas, immigration and asylum was originally placed under Pillar 3 of the EU, which dealt with Justice and Home Affairs. In 1997, however, the Amsterdam Treaty moved these policies from Pillar 3 to Pillar 1, signaling “a shift toward more supranational decision-making in this area,” as opposed to the intergovernmental method of Pillars 2 and 3.2
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This groundbreaking study concentrates on a set of critical economic factors that will shape future economic growth at the global level and offers a description of the possible evolution of their reach and scope. Our goal in pursuing this research is not to make precise predictions about growth rates or the size of individual economies, but to provide a guide for EU policy-makers by presenting an assessment of the possible implications of such trends for the global economy and the policy challenges they raise for Europe. In an attempt to respond to this need, this study concentrates on a set of critical economic factors that will shape future economic growth at the global level and offers a description of the possible evolution of their reach and scope, which often go beyond the purely economic dimension. Our ultimate goal is to provide a guide for policy-makers by presenting an assessment of the possible implications of such trends for the global economy and the policy challenges they raise for Europe.
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From the Executive Summary. A majority of Europeans would like the UK to remain a member of the European Union (EU), but at the same time they do not think that a Brexit would be the end of Europe. Whereas age or gender do not have a pronounced effect on how one views these matter, one factor clearly does: the more people support their own country’s membership in the EU, the more they want the UK to remain a member as well. The opposite is not true, however. Eurosceptics are not rooting for the UK to leave. These public opinion trends are demonstrated by the Bertelsmann Stiftung’s latest eupinions survey. eupinions conducts regular polls in all European member states to explore what European citizens think about current political issues. The latest wave of the survey is devoted to their views on the British referendum on membership in the EU.
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"July 1980"
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Mode of access: Internet.
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"Prepared for the Task Force on the Future of Illinois."
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"First edition: December 1, 1992."
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"Criminal and Juvenile Justice in Illinois."
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Pt. 1.The analysis of trends and concepts.
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Mode of access: Internet.