Página 1 dos resultados de 186 itens digitais encontrados em 0.003 segundos

Bridging the gap between cluster and grid computing

Alves, Albano; Pina, António
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
ENG; ENG
Relevância na Pesquisa
36.13%
The Internet computing model with its ubiquitous networking and computing infrastructure is driving a new class of interoperable applications that benefit both from high computing power and multiple Internet connections. In this context, grids are promising computing platforms that allow to aggregate distributed resources such as workstations and clusters to solve large-scale problems. However, because most parallel programming tools were primarily developed for MPP and cluster computing, to exploit the new environment higher abstraction and cooperative interfaces are required. Rocmeμ is a platform originally designed to support the operation of multi-SAN clusters that integrates application modeling and resource allocation. In this paper we show how the underlying resource oriented computation model provides the necessary abstractions to accommodate the migration from cluster to multicluster grid enabled computing.

Perspectiva econômica e modelo de negócio da tecnologia de telecomunicação nas redes de distribuição de energia elétrica no Brasil; Smart Grid Economic Perspective and Business Model in Brazi

Pascalicchio, Agostinho Celso
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 29/04/2011 PT
Relevância na Pesquisa
36.33%
Este trabalho tem por objetivo avaliar a perspectiva econômica e modelo de negócio da tecnologia de telecomunicação nas redes de distribuição de energia elétrica. Essa integração entre a tecnologia de telecomunicação e a rede de distribuição constitui um sistema conhecido como rede inteligente ou smart grid. Neste estudo são analisados os modelos de rede inteligentes mais significativos do mundo, os quais ainda se encontram em fase inicial. Na análise da implantação da rede inteligente em diversos países, observa-se a existência de diferentes motivações. Por exemplo, no caso norte-americano, trata-se dos esforços do setor de energia em garantir a confiabilidade no abastecimento. Na Europa, há um grande comprometimento com a redução de carbono e gases causadores do efeito estufa. No Brasil, busca-se uma estratégia para melhorar aspectos técnicos da distribuição, diminuir as perdas técnicas, eliminar ou reduzir o roubo de energia e ajustar a oferta de energia com o crescimento urbano e industrial, aprimorando a regulamentação sobre o setor. Além da ausência de padrões de telecomunicação, que se constitui em restrição para todos os projetos de smart grid, o Brasil apresenta grandes entraves para a implantação da rede inteligente...

Correlations and Functional Connections in a Population of Grid Cells

Dunn, Benjamin; Mørreaunet, Maria; Roudi, Yasser
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 25/02/2015 EN
Relevância na Pesquisa
26.52%
We study the statistics of spike trains of simultaneously recorded grid cells in freely behaving rats. We evaluate pairwise correlations between these cells and, using a maximum entropy kinetic pairwise model (kinetic Ising model), study their functional connectivity. Even when we account for the covariations in firing rates due to overlapping fields, both the pairwise correlations and functional connections decay as a function of the shortest distance between the vertices of the spatial firing pattern of pairs of grid cells, i.e. their phase difference. They take positive values between cells with nearby phases and approach zero or negative values for larger phase differences. We find similar results also when, in addition to correlations due to overlapping fields, we account for correlations due to theta oscillations and head directional inputs. The inferred connections between neurons in the same module and those from different modules can be both negative and positive, with a mean close to zero, but with the strongest inferred connections found between cells of the same module. Taken together, our results suggest that grid cells in the same module do indeed form a local network of interconnected neurons with a functional connectivity that supports a role for attractor dynamics in the generation of grid pattern.

Distribution Volume Tracking on Privacy-Enhanced Wireless Grid

Uzuner, Ozlem
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
Formato: 7 p.; 11942167 bytes; 409314 bytes; application/postscript; application/pdf
EN_US
Relevância na Pesquisa
36.41%
In this paper, we discuss a wireless grid in which users are highly mobile, and form ad-hoc and sometimes short-lived connections with other devices. As they roam through networks, the users may choose to employ privacy-enhancing technologies to address their privacy needs and benefit from the computational power of the grid for a variety of tasks, including sharing content. The high rate of mobility of the users on the wireless grid, when combined with privacy enhancing mechanisms and ad-hoc connections, makes it difficult to conclusively link devices and/or individuals with network activities and to hold them liable for particular downloads. Protecting intellectual property in this scenario requires a solution that can work in absence of knowledge about behavior of particular individuals. Building on previous work, we argue for a solution that ensures proper compensation to content owners without inhibiting use and dissemination of works. Our proposal is based on digital tracking for measuring distribution volume of content and compensation of authors based on this accounting information. The emphasis is on obtaining good estimates of rate of popularity of works, without keeping track of activities of individuals or devices. The contribution of this paper is a revenue protection mechanism...

Powering Up Productivity in Rural Lao PDR : Stimulating Small and Medium Enterprises to Use Electricity for Income Generation

Tuntivate, Voravate Tig
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
EN_US
Relevância na Pesquisa
36.33%
This study s broad goal was to identify opportunities for promoting productive uses of electricity in existing as well as among new small and medium enterprises (SMEs) in the rural villages of Lao PDR to generate income for rural people and promote economic development. To this end, the study team conducted a market analysis of current businesses and services, as well as major agro-processing and other income-generating activities in (i) six selected central and southern provinces connected to grid-based electricity and (ii) 10 rural villages of a remote northern district that rely on renewable energy based, off-grid power supply. Based on the survey results, the study team identified opportunities for the SMEs to switch to or adopt electricity for productive purposes; major obstacles faced by the SME owners in utilizing electricity more fully; and suggested ways to overcome these barriers, including the facilitating role of EdL (Electricité du Laos, the country s national utility company. This study relied on a social marketing survey conducted in February 2011 as the primary data source. It also drew from literature reviews and information gathered from government agencies and international organizations. Three sets of field surveys were conducted. The first set focused on rural villages with access to grid electricity whose main crop is rice; the surveys covered three central (Bolikhamxai...

Connection Charges and Electricity Access in Sub-Saharan Africa

Golumbeanu, Raluca; Barnes, Douglas
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
EN_US
Relevância na Pesquisa
36.53%
Sub-Saharan Africa trails other regions in providing access to electricity for poor urban and rural residents. This poor performance can be linked to various factors, including political interference in utility policy, higher investment costs and lower profitability of extending service to rural areas. But a major obstacle to wider access is the high charges consumers must pay to connect to the electricity network. The connection charges in Sub-Saharan Africa are among the highest in the world, which has resulted in low rates of electrification in many countries. This paper reviews ways to improve electrification rates by addressing the issue of high connection charges. Essential to the success of such efforts is concurrent political commitment to identify, examine, and implement various low-cost electrification approaches and financing solutions as part of a broad plan to improve access. Electricity companies can lower their connection-related costs, and thus consumer charges, by using a variety of low-cost technologies and materials in distribution networks and household connections; making bulk purchases of materials; and adjusting technical standards to reflect the lower loads of households that use a minimum amount of electricity. Strategies for lowering connection charges may also include spreading charges over a reasonable period...

Decentralized Energy Services to Fight Poverty : Outcome Driven Engagement of Small and Medium-size Enterprises in the Provision of Energy Services in IDA Countries

World Bank
Fonte: Washington, DC Publicador: Washington, DC
EN_US
Relevância na Pesquisa
36.25%
The Department for International Development (DFID)-Funded Energy Small and Medium Enterprises (SME) Program was created to support SMEs by helping countries unblock the factors that prevent their potential in the delivery of energy services. With thirteen energy projects in twelve countries and one regional program in Africa, the implementation of the program started considerably slower than expected but has demonstrated potential to make an impact in a relatively neglected area of delivering energy services to the poor. Lack of access to sufficient and sustainable supplies of energy affects as much as 90 percent of the population of many developing countries. Some 2 billion people are without electricity; a similar number remain dependent on fuels such as animal dung, crop residues, wood, and charcoal to cook their daily meals. Widespread inefficient production and use of traditional energy sources, such as fuel-wood and agricultural residues, pose economic, environmental, and health threats. Uneven distribution and use of modern energy sources, such as electricity, petroleum products, and liquefied or compressed natural gas, pose important issues of economics, equity, and quality of life. The Energy Sector Management Assistance Program (ESMAP) Energy SME program focused on off-grid electrification and biomass use as many communities and households that have yet to be electrified are relatively isolated...

Energy Sector Reform and the Pattern of the Poor : Energy Use and Supply, A Four Country Study - Botswana, Ghana, Honduras and Senegal

Prasad, Gisela
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
EN_US
Relevância na Pesquisa
26.43%
This project had the following objectives: to undertake a detailed assessment for four countries of the steps taken to reform the energy sector and their impact (or not) on various groups of poor households; to identify patterns of energy use by poor households in various situations; to identify patterns of supply of energy to poor households; and to identify links between the supply and the use of energy by poor households, which are capable of being directly impacted by sector reform. Such links include: the actual use of various sources of energy (e.g. electricity); the form in which the source is used (e.g. battery or grid connection); its associated cost (capital costs and fuel costs); and the nature of the delivery form (state utility or local off-grid company, retailer of batteries or of LPG). The design of a template for future assessment of the impact of sector reform on the poor in other countries. Through the use of local consultants, wherever possible, the engagement in capacity building for economic and policy analysis of the energy sector.

Scaling Up Access to Electricity : The Case of Lighting Africa

Murphy, Daniel; Sharma, Arsh
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
36.22%
This knowledge note is the first of three case studies that concerns scaling up access to electricity in Africa, Bangladesh, and Rwanda. Lighting Africa, a joint IFC and World Bank program launched in 2007, was the first private-sector-oriented effort to leverage new LED lighting technologies to build sustainable markets that provide safe, affordable, and modern off-grid lighting to communities in Africa that lack access to electricity. By 2030 the program aims to enable the private sector to reach 250 million people who now depend on fuel-based lighting. The case study for Africa is important, because the continent faces a huge rural electricity deficit. Global electrification in 2010 was estimated to be about 83 percent. The deficit of 17 percent encompasses some 1.2 billion people. Achieving universal access to modern energy services is one of the three complementary objectives of the Sustainable Energy for All (SE4ALL) initiative. Lighting Africa succeeded as a catalyst for the off-grid lighting market in Sub-Saharan Africa. Another success is apparent in the spectacular trajectory of solar lantern sales in Kenya. On the climate front...

The Economics of Renewable Energy Expansion in Rural Sub-Saharan Africa

Deichmann, Uwe; Meisner, Craig; Murray, Siobhan; Wheeler, David
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
EN_US
Relevância na Pesquisa
36.34%
Accelerating development in Sub-Saharan Africa will require massive expansion of access to electricity -- currently reaching only about one-third of households. This paper explores how essential economic development might be reconciled with the need to keep carbon emissions in check. The authors develop a geographically explicit framework and use spatial modeling and cost estimates from recent engineering studies to determine where stand-alone renewable energy generation is a cost effective alternative to centralized grid supply. The results suggest that decentralized renewable energy will likely play an important role in expanding rural energy access. But it will be the lowest cost option for a minority of households in Africa, even when likely cost reductions over the next 20 years are considered. Decentralized renewables are competitive mostly in remote and rural areas, while grid connected supply dominates denser areas where the majority of households reside. These findings underscore the need to de-carbonize the fuel mix for centralized power generation as it expands in Africa.

Power for All : Electricity Access Challenge in India

Banerjee, Sudeshna Ghosh; Barnes, Douglas; Singh, Bipul; Mayer, Kristy; Samad, Hussain
Fonte: Washington, DC: World Bank Publicador: Washington, DC: World Bank
EN_US
Relevância na Pesquisa
36.57%
India has led the developing world in addressing rural energy problems. By late 2012, the national electricity grid had reached 92 percent of India s rural villages, about 880 million people. In more remote areas and those with geographically difficult terrain, where grid extension is not economically viable, off-grid solutions using renewable-energy sources for electricity generation and distribution have been promoted. The positive results of the country s rural energy policies and institutions have contributed greatly to reducing the number of people globally who remain without electricity access. Yet, owing mainly to its large population, India has by far the world s largest number of households without electricity. More than one-quarter of its population or about 311 million people, the vast majority of whom live in poorer rural areas, still lack an electricity connection; less than half of all households in the poorest income group have electricity. Among households with electricity service, hundreds of millions lack reliable power supply.

Electrical design for a wave buoy; Diseño eléctrico de una boya para energía olamotriz

Hoya Arija, Sara
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: info:eu-repo/semantics/bachelorThesis; info:eu-repo/semantics/masterThesis Formato: application/pdf; application/pdf
ENG
Relevância na Pesquisa
26.46%
Renewable energies have been taking an important role in the disperse generation in the last years. A new renewable energy is the wave power, that transports energy by ocean surface waves, and capture that energy to do useful work. In this project is studied, discussed and designed the electrical parts needed to transform the wave power into electrical power as the control of the buoy (reactive and latching control), system (electrical or hydraulic), generators (linear or rotating),converter systems (depending on generator, speed control and grid), grid connections and transmissions systems, cables and transformers. The material produced in this report is definitely the beginning of new knowledge which can be deeply developed. From these studies some conclusions can be done as electrical systems offer excellent prospects for superior performance and other benefits compared with hydraulic systems, and the development of electrical system prototypes is justified. Phase control avoids the drawback of high power peaks keeping the advantage of increased power extraction. The rotating generation is preferred against a linear electric power generation in terms of efficiency and cost. In a plant, the wave energy converters (base units) can be connected in larger arrays ranging from tenths up to thousands of individual converters. The connections of these converters to the grid can be implemented in various ways (converters and transformer offshore or onshore and connections cables schemes) depending on the size of the farm and the proximity to the grid among other criteria as availability or cost. Taking into account cable losses and complexity the better option is place these devices onshore for small farms close to the grid and offshore for medium to large farms. Comparing connection schemes in terms of cable cost...

World Bank Group Support to Electricity Access, FY2000-2014; An Independent Evaluation

Independent Evaluation Group
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Report; Publications & Research; Publications & Research :: Working Paper
ENGLISH; EN_US
Relevância na Pesquisa
36.55%
The World Bank Group has committed to achieving universal access to electricity by 2030 under the Sustainable Energy for All (SE4All) initiative. This is a daunting challenge: more than 1 billion people do not have access, and another 1 billion have chronically inadequate or unreliable service. Most of those without access are poor, and the largest share is in Sub-Saharan Africa. Achieving universal access within 15 years for the low-access countries (those with under 50 percent coverage) requires a quantum leap from their present pace of 1.6 million connections per year to 14.6 million per year until 2030. The investment needed would be about $37 billion per year, including erasing generation deficits and meeting demand from economic growth. By comparison, in recent years, low-access countries received an average of $3.6 billion per year for their electricity sectors from public and private sources, including $1.5 billion per year from the World Bank Group. Development outcomes of the Bank Group’s assistance were generally favorable compared with other infrastructure sectors. However...

Electricity Connections and Firm Performance in 183 Countries

Geginat, Carolin; Ramalho, Rita
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Working Paper; Publications & Research :: Policy Research Working Paper; Publications & Research
ENGLISH; EN_US
Relevância na Pesquisa
36.11%
This paper presents new data on electricity connections for businesses in 183 economies. The data cover information on procedures, time, and cost that a small or medium size business with a moderate electricity need has to invest to obtain a new electricity connection. The study finds significant variation in the time and cost to obtain such an electricity connection across countries. In low-income countries, for instance, it takes on average nearly twice as long as in high-income countries to connect a new customer to electricity, while the cost associated with a comparable connection is 70 times higher. The study finds that the poor performance of distribution utilities in low-income countries cannot only be explained by differences in income levels. The overall level of bureaucracy appears to be another important factor. The study also finds the data to be correlated with existing measures of the effectiveness of the electricity sector, suggesting that the hurdles related to obtaining an electricity connection mirror other problems in the sector...

Scaling Up Access to Electricity : The Case of Bangladesh

Sadeque, Zubair; Rysankova, Dana; Elahi, Raihan; Soni, Ruchi
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Journal Article; Publications & Research :: Brief; Publications & Research
ENGLISH; EN_US
Relevância na Pesquisa
36.33%
This knowledge note is the second of three case studies that concerns scaling up access to electricity in Africa, Bangladesh, and Rwanda. Since its inception in 2003, Bangladesh's solar home system program has installed about three million electrification systems in rural households, two-thirds of them in the last three years. The program is the most dynamic off-grid electrification program in the world, benefitting more than 15 million people and contributing about 130 MW in renewable energy generation capacity. The case study for Bangladesh is interesting, because off-grid electrification is crucial to reaching universal access. Achieving universal access to modern energy services is one of the three complementary objectives of the Sustainable Energy for All (SE4ALL) initiative. Bangladesh's rural electrification program was initiated in 1977 with the creation of the Rural Electrification Board (REB). Yet, it was estimated that at the prevailing pace of grid electrification, Bangladesh was going to take 50 years to reach universal access. By 2002...

Rwanda - Extending Access to Energy : Lessons from a Sector-Wide Approach

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Tipo: Publications & Research :: ESMAP Paper; Publications & Research
ENGLISH; EN_US
Relevância na Pesquisa
36.19%
Rwanda is one of the first countries to use a Sector Wide-Approach (SWAp) in the energy sector to increase access to electricity. The SWAp emerged in the 1990s as an alternative to traditional development aid. The SWAp-based on a country-led, results-focused framework-encourages engagement across all sector stakeholders to ensure that investments work together to contribute to desired outcomes. With the assistance of energy sector management assistance program's Africa Renewable Energy Access (AFREA) program. This report provides a number of key lessons realized from the Rwanda energy SWAp for development partners and governments considering using such an approach. Country and government ownership and leadership is essential for efficient program planning and implementation, as is an alignment with national priorities and policies. In 2009, Rwanda initiated a SWAp in the energy sector to help achieve its target of increasing access to electricity from 6 percent of the population to 16 percent over a five-year period...

The Welfare Impact of Rural Electrification : A Reassessment of the Costs and Benefits

Independent Evaluation Group
Fonte: Washington, DC : World Bank Publicador: Washington, DC : World Bank
Tipo: Publications & Research :: Publication; Publications & Research :: Publication
ENGLISH; EN_US
Relevância na Pesquisa
26.46%
It has long been claimed that rural electrification greatly improves the quality of life. Lighting alone brings benefits such as increased study time and improved study environment for school children, extended hours for small businesses, and greater security. But electrification brings more than light. It's second most common use is for television, which brings both entertainment and information. The people who live in rural areas greatly appreciate these benefits and are willing to pay for them at levels more than sufficient to cover the costs. However, the evaluation of these and other benefits, as well as of their distribution, has been sparse. This report reviews recent methodological advances made in measuring the benefits of rural electrification (RE) and commends them. It also notes that the understanding of the techniques shown in project documents is sometimes weak, and quality control for the economic analysis in project documents lacking. This study shows that willingness to pay for electricity is high...

One Goal, Two Paths : Achieving Universal Access to Modern Energy in East Asia and the Pacific

World Bank
Fonte: World Bank Publicador: World Bank
Tipo: Publications & Research :: Publication; Publications & Research :: Publication
ENGLISH
Relevância na Pesquisa
36.59%
The purpose of the current flagship report is to address energy access and related developmental issues in East Asia Pacific (EAP) that so far have received less attention compared to the macro energy issues of climate change and reduction of greenhouse gas (GHG) emissions. EAP countries have two steep paths to climb to achieve universal access to modern energy: electricity and modern cooking solutions. Approximately 170 million people, or 34 million households, in EAP countries do not have electricity connections in their homes. This number is equivalent to approximately 9 percent of the Region's total population, and 30 percent of the Region's population excluding China. Moreover, approximately 6 times that number, or over 1 billion people, still lack access to modern cooking solutions. In addition, EAP is exceeded by only Sub Saharan Africa and South Asia in the number of people who lack access to electricity. However, access to both electricity and modern cooking solutions is essential to address the enduring impacts of poverty and to move the poor onto a rising development trajectory. The link between access to modern energy and development is most clearly defined by the Millennium Development Goals (MDG). The MDGs were formulated to reduce global poverty while increasing education...

A Study on the Charging of Electric Vehicles On a Prototypical Residential Feeder

Taylor, David
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
36.46%
Due to recent concerns regarding energy conservation and dependence on fossil fuels, the efficient integration of electric vehicle populations’ in the future smart grid has become a significant area of research. Despite the heavy penetration of smart meters throughout North America and Europe a lack of research exists utilizing real consumption data. Making use of smart meter data, a model of a prototypical residential feeder was created to observe the effects of increased electric vehicle penetration on the selected feeder. Simulations of the current operation of the feeder were performed along with modeled uncoordinated, coordinated, and coordinated vehicle to grid charging of electric vehicles. As expected, it was found that the normal operation of the feeder is subject to several inefficiencies which are made worse by uncoordinated charging of electric vehicles. Significant improvements in the considered operational parameters were found as a result of the coordinated charging of vehicles using a quadratic programming based control algorithm. Further it was found, that the use of coordinated vehicle to grid connections only produces marginal benefits over standard connections. Leading to the conclusion that development of charging controls is more significant to the mitigation of electric vehicle charging effects than the integration of vehicle to grid connections.; Thesis (Master...

Correlations and functional connections in a population of grid cells

Dunn, Benjamin; Mørreaunet, Maria; Roudi, Yasser
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.55%
We study the statistics of spike trains of simultaneously recorded grid cells in freely behaving rats. We evaluate pairwise correlations between these cells and, using a generalized linear model (kinetic Ising model), study their functional connectivity. Even when we account for the covariations in firing rates due to overlapping fields, both the pairwise correlations and functional connections decay as a function of the shortest distance between the vertices of the spatial firing pattern of pairs of grid cells, i.e. their phase difference. The functional connectivity takes positive values between cells with nearby phases and approaches zero or negative values for larger phase differences. We also find similar results when, in addition to correlations due to overlapping fields, we account for correlations due to theta oscillations and head directional inputs. The inferred connections between neurons can be both negative and positive regardless of whether the cells share common spatial firing characteristics, that is, whether they belong to the same modules, or not. The mean strength of these inferred connections is close to zero, but the strongest inferred connections are found between cells of the same module. Taken together, our results suggest that grid cells in the same module do indeed form a local network of interconnected neurons with a functional connectivity that supports a role for attractor dynamics in the generation of the grid pattern.; Comment: Accepted for publication in PLoS Computational Biology