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System Efficiency (system + efficiency)
Selected AbstractsComparison of coded orthogonal frequency division multiplexing and multicarrier code division multiple access systems for power line communicationsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 9 2004P. L. Katsis Abstract Orthogonal frequency division multiplexing (OFDM) and multicarrier code division multiple access (MC-CDMA) systems are comparatively evaluated for power line communications (PLC) in a frequency-selective fading environment with additive coloured Gaussian noise which is used to model the actual in-home power line channel. OFDM serves as a benchmark in order to measure the performance of various MC-CDMA systems, since multicarrier modulation systems are considered the best candidate for this kind of channel. Both single-user and multi-user cases are taken into account, making use of the appropriate combiner schemes to take full advantage of each case. System efficiency is enhanced by the application of different coding techniques, a fact which shows that powerful coding can make the difference under such a hostile medium. The impact of block interleaving is investigated, while the simulation examines how different modulation schemes fair under the imposed channel conditions as well. The performance of the system is assessed by the commonly used bit error rate vs signal-to-noise ratio diagrams and there is also a comparison regarding throughput efficiency among all the tested systems. As stated in Section 4, a promising PLC application is attained. Copyright © 2004 John Wiley & Sons, Ltd. [source] FLOX® Steam Reforming for PEM Fuel Cell Systems,FUEL CELLS, Issue 4 2004H.-P. Schmid Abstract Primary energy savings and CO2 reduction is one of the key motivations for the use of fuel cell systems in the energy sector. A benchmark of domestic cogeneration by PEMFC with existing large scale power production systems such as combined steam-gas turbine cycle, clearly reveals that only fuel cell systems optimising overall energy efficiency (>,85%) and electrical efficiencies (>,35%) show significant primary energy savings, about 10%, compared with the best competing technology. In this context, fuel processing technology plays a dominant role. A comparison of autothermal and steam reforming concepts in a PEMFC system shows inherent advantages in terms of efficiency at low complexity for the latter. The main reason for this is that steam reforming allows for the straightforward and effective use of the anode-off gas energy in the reformer burner. Consequently, practical electrical system efficiencies over 40% seem to be achievable, most likely by steam reformers. FLOX®-steam reforming technology has reached a high state of maturity, offering diverse advantages including: compact design, stable anode off-gas usage, high efficiency, as well as simple control behaviour. Scaling of the concept is straightforward and offers an opportunity for efficient adaptation to smaller (1,kW) and larger (50,kW) units. [source] Geothermal-based hydrogen production using thermochemical and hybrid cycles: A review and analysisINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2010M. Tolga Balta Abstract Geothermal-based hydrogen production, which basically uses geothermal energy for hydrogen production, appears to be an environmentally conscious and sustainable option for the countries with abundant geothermal energy resources. In this study, four potential methods are identified and proposed for geothermal-based hydrogen production, namely: (i) direct production of hydrogen from the geothermal steam, (ii) through conventional water electrolysis using the electricity generated through geothermal power plant, (iii) by using both geothermal heat and electricity for high temperature steam electrolysis and/or hybrid processes, and (iv) by using the heat available from geothermal resource in thermochemical processes. Nowadays, most researches are focused on high-temperature electrolysis and thermochemical processes. Here we essentially discuss some potential low-temperature thermochemical and hybrid cycles for geothermal-based hydrogen production, due to their wider practicality, and examine them as a sustainable option for hydrogen production using geothermal heat. We also assess their thermodynamic performance through energy and exergy efficiencies. The results show that these cycles have good potential and attractive overall system efficiencies over 50% based on a complete reaction approach. The copper-chlorine cycle is identified as a highly promising cycle for geothermal-hydrogen production. Copyright © 2009 John Wiley & Sons, Ltd. [source] An operational algorithm for residential cogeneration systems based on the monitored daily-basis energy demandELECTRICAL ENGINEERING IN JAPAN, Issue 2 2010Yuka Yamagishi Abstract Residential cogeneration systems with PEFC are promising as distributed power system resources with the ability to improve energy system efficiency. However, it is important to develop an efficient algorithm for operation because the energy demand at each house differs greatly from day to day. In this paper, we propose an operational algorithm and evaluate it from the viewpoint of energy conservation and economic effectiveness based on the energy demand characteristics. In the algorithm, the hot water and electricity demand on the next day are estimated based on the average of past data. The results of simulations using actually monitored energy demand data indicate that (1) the greater the electrical demand of a household, the more effective this algorithm becomes with respect to energy conservation; (2) the greater the hot water demand of a household, the more effective this algorithm becomes with respect to economic effectiveness. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(2): 37,45, 2010; Published online in Wiley InterScience (www.interscience.wiley. com). DOI 10.1002/eej.20892 [source] A critique of the World Health Organisation's evaluation of health system performanceHEALTH ECONOMICS, Issue 5 2003Jeff Richardson Abstract The World Health Organisation's (WHO) approach to the measurement of health system efficiency is briefly described. Four arguments are then presented. First, equity of finance should not be a criterion for the evaluation of a health system and, more generally, the same objectives and importance weights should not be imposed upon all countries. Secondly, the numerical value of the importance weights do not reflect their true importance in the country rankings. Thirdly, the model for combining the different objectives into a single index of system performance is problematical and alternative models are shown to alter system rankings. The WHO statistical analysis is replicated and used to support the fourth argument which is that, contrary to the author's assertion, their methods cannot separate true inefficiency from random error. The procedure is also subject to omitted variable bias. The econometric model for all countries has very poor predictive power for the subset of OECD countries and it is outperformed by two simpler algorithms. Country rankings based upon the model are correspondingly unreliable. It is concluded that, despite these problems, the study is a landmark in the evolution of system evaluation, but one which requires significant revision. Copyright © 2002 John Wiley & Sons, Ltd. [source] Energy Conservation in Urban AreasIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 1 2008Hideharu Sugihara Member Abstract This article outlines the energy conservation measures in the civilian sector from a few different viewpoint regarding energy conservation in cities. First, the energy consumption trends in the business and residential sectors are discussed, focusing the importance of energy conservation measures in applications such as home heating, water heating and specific power demand. Second, as a measure to reduce energy demand itself, energy conservation by way of applying heat insulating materials to buildings and changing the life style of residents is considered. And from the viewpoint of improving the energy system efficiency, additionally discussed here are the measures to improve the efficiency of each energy equipment such as air-conditioners and co-generation equipment, and the characteristics of District heating and cooling systems such as the local energy infrastructures. Lastly, from the knowledge obtained through model analyses by the authors, a scheme is recommended that would be one of the most efficient city-energy schemes where the energy systems including heat pumps, co-generators or equipment using solar power are utilized for their best-suited applications for business and residential customers. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Setting the rules: private power, political underpinnings, and legitimacy in global monetary and financial governanceINTERNATIONAL AFFAIRS, Issue 3 2008GEOFFREY R. D. UNDERHILL The role of private market agents in global monetary and financial governance has increased as globalization has proceeded. This shift in both markets and patterns of governance has often been encouraged by states themselves in pursuit of liberalization policies. Much of the literature views these developments in a positive light, yet there are other aspects of these developments that also merit attention. This article supports its central propositions with two cases of emerging global financial governance processes: the Basel II capital adequacy standards for international banking supervision and the International Organization of Securities Commissions-based transnational regulatory processes underpinning the functioning of cross-border securities markets. Based on the case findings, the article argues first that private sector self-regulation and/or public-private partnership in governance processes can leave public authorities vulnerable to dependence on the information and expertise provided by private agents in a fast-moving market environment. Policy in the vital domain of financial regulation has been increasingly aligned to private sector preferences to a degree that should raise fears of bureaucratic capture. Second, the article contends that the overall outcome in terms of global financial system efficiency and stability has been mixed, bringing a range of important benefits but also instability and crisis for many societies to a degree that has led to challenges to global governance itself. The case material indicates that the input, output and accountability phases of legitimacy in global monetary and financial governance are highly problematic, and much of the problem relates to the way in which private market agents are integrated into the decision-making process. Third, the article posits that a better consideration of these three ,phases' of legitimacy and their interrelationships is likely to enhance the political underpinnings and legitimacy of global financial and monetary order. [source] Second law analysis of two-stage compression transcritical CO2 heat pump cycleINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2008Arif Emre Özgür Abstract Because of the global warming impact of hydro fluorocarbons, the uses of natural refrigerants in automotive and HVAC industries have received worldwide attention. CO2 is the most promising refrigerant in these industries, especially the transcritical CO2 refrigeration cycle. The objective of this work is to identify the main factors that affect two-stage compression transcritical CO2 system efficiency. A second law of thermodynamic analysis on the entire two-stage CO2 cycle is conducted so that the exergy destruction of each system component can be deduced and ranked, allowing future efforts to focus on improving the components that have the highest potential for advancement. The inter-stage pressure is used as a variable parameter in the analysis study. The second law efficiency, coefficient of cooling performance and total exergy destruction of the system variations with the inter-stage pressure are presented graphically. It was concluded that there is an optimum inter-stage pressure that maximizes both first law and second law efficiencies. Copyright © 2008 John Wiley & Sons, Ltd. [source] Development of an optimization model for energy systems planning in the Region of WaterlooINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2008Y. P. Cai Abstract In this study, a large-scale dynamic optimization model (University of Regina Energy Model, UREM) has been developed for supporting long-term energy systems planning in the Region of Waterloo. The model can describe energy management systems as networks of a series of energy flows, transferring extracted/imported energy resources to end users through a variety of conversion and transmission technologies over a number of periods. It can successfully incorporate optimization models, scenario development and policy analysis within a general framework. Complexities in energy management systems can be systematically reflected; thus, the applicability of the modeling process can be highly enhanced. Four scenarios (including a reference case) are considered based on different energy management policies and sustainable development strategies for in-depth analysis of interactions existing among energy, socio-economy and environment in the Region. Useful solutions for the planning of energy management systems have been generated, reflecting trade-offs among energy-related, environmental and economic considerations. They are helpful for supporting (a) adjustment or justification of the existing allocation patterns of energy resources and services, (b) allocations of renewable energy resources, (c) formulation of local policies regarding energy consumption, economic development and energy structure, and (d) analysis of interactions among economic cost, system efficiency, emission mitigation and energy-supply security. Results also indicate that UREM can help tackle dynamic and interactive characteristics of the energy management system in the Region of Waterloo and can address issues concerning cost-effective allocation of energy resources and services. Thus, it can be used by decision makers as an effective technique in examining and visualizing impacts of energy and environmental policies, regional/community development strategies and emission reduction measures within an integrated and dynamic framework. Copyright © 2008 John Wiley & Sons, Ltd. [source] A new type of EFHAT power generation system with effective utilization of latent heatINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2005Hongguang Jin Abstract On the basis of synergetic integration of an externally fired humid air turbine (EFHAT) cycle and effective recovery of latent heat from the exhaust gas of gas turbine, we have proposed a new type of EFHAT power generation system with effective utilization of latent heat, different from traditional EFHAT system. Due to use of clean humid air as working substance, latent heat can be recovered and utilized to generate hot water for the humidifier. This will enhance the humidification ability, giving rise to performance improvement of the system. As a result, at the turbine inlet temperature of 1123 K, the thermal efficiency of this new system may be expected to be as high as 47,48%. Additionally, we obtained the analytical expressions of system performance, and disclosed the relative relationship of system efficiency between the new EFHAT system and the pure externally fired power system. Copyright © 2005 John Wiley & Sons, Ltd. [source] Comparison of energy and exergy efficiencies of an underground solar thermal storage systemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 4 2004H. Hüseyin Öztürk Abstract In this experimental study, solar energy was stored daily using the volcanic material with the sensible heat technique. The external heat collection unit consisted of 27 m2 of south-facing solar air collectors mounted at a 55° tilt angle. The dimensions of the packed-bed heat storage unit were 6 × 2 × 0.6 m deep. The packed-bed heat storage unit was built under the soil. The heat storage unit was filled with 6480 kg of volcanic material. Energy and exergy analyses were applied in order to evaluate the system efficiency. During the charging periods, the average daily rates of thermal energy and exergy stored in the heat storage unit were 1242 and 36.33 W, respectively. Since the rate of exergy depends on the temperature of the heat transfer fluid and surrounding, the rate of exergy increased as the difference between the inlet and outlet temperatures of the heat transfer fluid increased during the charging periods. It was found that the average daily net energy and exergy efficiencies in the charging periods were 39.7 and 2.03%, respectively. The average daily net energy efficiency of the heat storage system remained nearly constant during the charging periods. The maximum energy and exergy efficiencies of the heat storage system were 52.9 and 4.9%, respectively. Copyright © 2004 John Wiley & Sons, Ltd. [source] Radio resource management across multiple protocol layers in satellite networks: a tutorial overviewINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 5 2005Paolo Barsocchi Abstract Satellite transmissions have an important role in telephone communications, television broadcasting, computer communications, maritime navigation, and military command and control. Moreover, in many situations they may be the only possible communication set-up. Trends in telecommunications indicate that four major growth market/service areas are messaging and navigation services (wireless and satellite), mobility services (wireless and satellite), video delivery services (cable and satellite), and interactive multimedia services (fibre/cable, satellite). When using geostationary satellites (GEO), the long propagation delay may have great impact, given the end-to-end delay user's requirements of relevant applications; moreover, atmospheric conditions may seriously affect data transmission. Since satellite bandwidth is a relatively scarce resource compared to the terrestrial one (e.g. in optical transport networks), and the environment is harsher, resource management of the radio segment plays an important role in the system's efficiency and economy. The radio resource management (RMM) entity is responsible for the utilization of the air interface resources, and covers power control, handover, admission control, congestion control, bandwidth allocation, and packet scheduling. RRM functions are crucial for the best possible utilization of the capacity. RRM functions can be implemented in different ways, thus having an impact on the overall system efficiency. This tutorial aims to provide an overview of satellite transmission aspects at various OSI layers, with emphasis on the MAC layer; some cross-layer solutions for bandwidth allocation are also indicated. Far from being an exhaustive survey (mainly due to the extensive nature of the subject), it offers the readers an extensive bibliography, which could be used for further research on specific aspects. Copyright © 2005 John Wiley & Sons, Ltd. [source] Irrigation and drainage systems research and development in the 21st century,IRRIGATION AND DRAINAGE, Issue 4 2002Bart Schultz irrigation; drainage; développement durable; système de réseau Abstract One critical problem confronting mankind today is how to manage the intensifying competition for water between expanding urban centres, traditional agricultural activities and in-stream water uses dictated by environmental concerns. In the agricultural sector, the dwindling number of economically attractive sites for large-scale irrigation and drainage projects limits the prospects of increasing the gross cultivated area. Therefore, the required increase in agricultural production will necessarily rely largely on a more accurate estimation of crop water requirements on the one hand, and on major improvements in the construction, operation, management and performance of existing irrigation and drainage systems, on the other. The failings of present systems and the inability to sustainably exploit surface and groundwater resources can be attributed essentially to poor planning, design, system management and development. This is partly due to the inability of engineers, planners and managers to adequately quantify the effects of irrigation and drainage projects on water resources and to use these effects as guidelines for improving technology, design and management. To take full advantage of investments in agriculture, a major effort is required to modernize irrigation and drainage systems and to further develop appropriate management strategies compatible with the financial and socio-economic trends, and the environment. This calls for a holistic approach to irrigation and drainage management and monitoring so as to increase food production, conserve water, prevent soil salinization and waterlogging, and to protect the environment. All this requires, among others, enhanced research and a variety of tools such as water control and regulation equipment, remote sensing, geographic information systems, decision support systems and models, as well as field survey and evaluation techniques. To tackle this challenge, we need to focus on the following issues: affordability with respect to the application of new technologies; procedures for integrated planning and management of irrigation and drainage systems; analysis to identify causes and effects constraining irrigation and drainage system performance; evapotranspiration and related calculation methods; estimation of crop water requirements; technologies for the design, construction and modernization of irrigation and drainage systems; strategies to improve irrigation and drainage system efficiency; environmental impacts of irrigation and drainage and measures for creating and maintaining sustainability; institutional strengthening, proper financial assessment, capacity building, training and education. Copyright © 2002 John Wiley & Sons, Ltd. Résumé Aujourd'hui le problème critique pour l'humanité est comment manier la compétition intensifiante pour de l'eau entre les centres urbains en expansion, pour des activités traditionnellement agricoles et pour l'usage de l'eau fluviale prescrit par des conditions écologistes. Dans le secteur agricole les perspectives d'agrandir les champs cultivés bruts sont limitées par le nombre diminuant des terrains économiquement attractifs pour des projets d'irrigation et du drainage de grande envergure. Par conséquent l'augmentation nécessaire de la production agricole comptera surtout sur une évaluation plus précise du besoin des plantes d'un côté, et de l'autre sur de grandes améliorations dans la construction, dans l'opération, dans le management et dans la performance des systèmes d'irrigation et du drainage. On peut attribuer les défauts des systèmes actuels et l'incompétence d'exploiter durablement les ressources hydriques de surface et souterraines au planification, au système de la gestion de l'eau et au système du développement. Cela est partiellement dû à l'incapacité des ingénieurs, des planificateurs et des gérants, de quantifier adéquatement les effets des projets d'irrigation et de drainage sur les ressources hydriques et d'utiliser ces résultats pour améliorer la technologie, la planification et la gestion de l'eau. Pour profiter le mieux possible des investissements dans l'agriculture, on exige un effort considérable pour moderniser les systèmes d'irrigation et de drainage et pour développer des stratégies de gestion de l'eau qui doivent être appropriées et compatibles avec les tendances financières et socio-économiques et avec l'environnement. Ceci a besoin d'une procédure holistique pour la gestion et le monitorage de l'eau, pour augmenter la production d'aliments, pour conserver l'eau, pour prévenir la salination du sol et pour protéger l'environnement. Tout cela demande, entre autres choses, une recherche d'avant-garde et une variété d'instruments comme les contrôles du régime hydrique et les appareils de régulation, la télédétection, les systèmes de l'information géographique, les systèmes et les modèles de support de décision et de même les levés sur le terrain et les techniques d'évaluation. Pour entreprendre ce défi nous devons nous concentrer sur les questions suivantes: capacité de mettre enoeuvre des technologies nouvelles; le développement des procédures pour intégrer la planification et la gestion des systèmes d'irrigation et de drainage; l'analyse pour identifier les causes et les effets de forcer à la performance des systèmes d'irrigation et de drainage; l'évapotranspiration et les méthodes de calcul en question; l'évaluation des exigences hydriques des cultures; les technologies pour le dessein, la construction et la modernisation des projets d'irrigation et de drainage; les stratégies pour améliorer l'efficacité des systèmes d'irrigation et de drainage; les impacts des projets d'irrigation et de drainage et des mesures appropriées pour créer et entretenir la durabilité; l'amélioration du contexte institutionnel, l'évaluation financière, la formation et l'amélioration des compétences techniques. Copyright © 2002 John Wiley & Sons, Ltd. [source] Excitation of the Intrinsic Conduction System Through His and Interventricular Septal PacingPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 4 2006TIMOTHY G LASKE Background: Direct His bundle pacing results in rapid synchronous ventricular activation. However, clinical experiences with such pacing have been associated with long procedure times and compromised pacing and sensing performance. Methods: We evaluated myocardial activation sequences (AS) for pacing of the His bundle and peri-His region and assessed acute pacing performance using custom-designed plunge electrodes. Unipolar pacing was performed in isolated swine hearts (n = 10) using four quadripolar stimulation/sensing electrodes implanted into the interventricular septum and equally spaced between the membranous septum and the coronary sinus ostium (zones 1,4, respectively; electrode depth (ED) 1 = most distal, ED 4 = most proximal). Optimal pacing sites were defined as: pacing thresholds ,1.5 V, a P-R ratio of ,0.5, and ,50% occurrence of an intrinsic midseptal left ventricular (LV) endocardial electrical breakout (BO) and activation pattern. Results: Pacing thresholds improved with greater depth of electrode location within the septum (ED 1: 1.51 ± 0.8 V vs ED 4: 5.2 ± 3.8 V, P < 0.001), as did the P-R ratio (0.34 ± 0.6 vs 0.78 ± 1.0, P < 0.05). His potentials were only observed in zone 1 and 2 electrodes (0.12 and 0.02 mV, respectively). Only electrodes in zones 1 and 2 produced LV endocardial electrical BOs in the midseptal region that demonstrated an intrinsic-like endocardial AS. Depth 1 and 2 electrodes (11.75 and 8.75 mm, respectively) in zone 1 satisfied all three optimal pacing site requirements. Conclusions: This study has shown that LV activation patterns similar to sinus rhythm may be achieved without direct activation of the His bundle, while maintaining acceptable pacing and sensing performance. These data indicate that pacing systems designed to stimulate the tissues below the point at which the His bundle penetrates the central fibrous body may provide improved system efficiency and LV performance in comparison to both direct His bundle pacing and traditional pacing sites. [source] INSTITUTIONS, BANKING DEVELOPMENT, AND ECONOMIC GROWTHTHE DEVELOPING ECONOMIES, Issue 4 2009M. Sami NABI O16; O17; O41 Does the institutional environment affect the causal relationship between banking development and economic growth? In the theoretical section of this paper, we develop an endogenous growth model where the institutional environment is captured through two indicators: judicial system efficiency and easiness of informal trade. We show that an improvement in the institutional environment has two effects. First, it intensifies the causality direction from banking to economic growth through a reduction in defaulting loans. Second, it reduces the interest rate spread. In the empirical section of the paper, we find bidirectional causality when analyzing 22 Middle Eastern and North African countries over the period 1984,2004. The first causality, which runs from banking development to economic growth, is more intense in countries with more developed institutional environment. The second causality runs from economic growth to banking and indicates that a more developed economy has a more developed banking system. [source] Lung Transplantation in the United States, 1999,2008AMERICAN JOURNAL OF TRANSPLANTATION, Issue 4p2 2010R. D. Yusen This article highlights trends and changes in lung and heart,lung transplantation in the United States from 1999 to 2008. While adult lung transplantation grew significantly over the past decade, rates of heart,lung and pediatric lung transplantation have remained low. Since implementation of the lung allocation score (LAS) donor allocation system in 2005, decreases in the number of active waiting list patients, waiting times for lung transplantation and death rates on the waiting list have occurred. However, characteristics of recipients transplanted in the LAS era differed from those transplanted earlier. The proportion of candidates undergoing lung transplantation for chronic obstructive pulmonary disease decreased, while increasing for those with pulmonary fibrosis. In the LAS era, older, sicker and previously transplanted candidates underwent transplantation more frequently compared with the previous era. Despite these changes, when compared with the pre-LAS era, 1-year survival after lung transplantation did not significantly change after LAS inception. The long-term effects of the change in the characteristics of lung transplant recipients on overall outcomes for lung transplantation remain unknown. Continued surveillance and refinements to the LAS system will affect the distribution and types of candidates transplanted and hopefully lead to improved system efficiency and outcomes. [source] Health reform in Alberta: The introduction of health regionsCANADIAN PUBLIC ADMINISTRATION/ADMINISTRATION PUBLIQUE DU CANADA, Issue 2 2008John Church Consistent with the larger fiscal agenda, the government's intention was to address health-care system efficiency through larger integrated management and governance structures. In this article, the authors examine why Alberta decided to create regional health authorities for the management and delivery of a significant range of health services. In examining the interaction of ideas, interests and institutions, the authors conclude that the government was partially successful in aligning existing institutional and interest relationships with an emerging political consensus about cost and sustainability of the health-care system. Sommaire: En 1994, le gouvernement de l'Alberta a adopté la loi intitulée Regional Health Authorities Act (Loi sur les offices régionaux de santé) en vue d'abolir près de 200 commissions hospitalières et commissions de santé publique locales et de les remplacer par dix-sept offices régionaux de la santé. Conformément au programme fiscal plus large, l'intention du gouvernement était d'examiner l'efficience du système des soins de santé grâce à des structures intégrées de gestion et de gouvernance plus vastes. Dans le présent article, les auteurs examinent les raisons pour lesquelles l'Alberta a décidé de créer des offices régionaux de la santé pour la gestion et la prestation d'une gamme importante de services de santé. Après avoir étudié les interactions d'idées, d'intérêts et d'institutions, les auteurs ont conclu que le gouvernement avait partiellement réussi à aligner les relations institutionnelles et les relations d'intérêts existantes sur un consensus politique émergent au sujet des coûts et de la viabilité du système de soins de santé. [source] Radio resource management across multiple protocol layers in satellite networks: a tutorial overviewINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 5 2005Paolo Barsocchi Abstract Satellite transmissions have an important role in telephone communications, television broadcasting, computer communications, maritime navigation, and military command and control. Moreover, in many situations they may be the only possible communication set-up. Trends in telecommunications indicate that four major growth market/service areas are messaging and navigation services (wireless and satellite), mobility services (wireless and satellite), video delivery services (cable and satellite), and interactive multimedia services (fibre/cable, satellite). When using geostationary satellites (GEO), the long propagation delay may have great impact, given the end-to-end delay user's requirements of relevant applications; moreover, atmospheric conditions may seriously affect data transmission. Since satellite bandwidth is a relatively scarce resource compared to the terrestrial one (e.g. in optical transport networks), and the environment is harsher, resource management of the radio segment plays an important role in the system's efficiency and economy. The radio resource management (RMM) entity is responsible for the utilization of the air interface resources, and covers power control, handover, admission control, congestion control, bandwidth allocation, and packet scheduling. RRM functions are crucial for the best possible utilization of the capacity. RRM functions can be implemented in different ways, thus having an impact on the overall system efficiency. This tutorial aims to provide an overview of satellite transmission aspects at various OSI layers, with emphasis on the MAC layer; some cross-layer solutions for bandwidth allocation are also indicated. Far from being an exhaustive survey (mainly due to the extensive nature of the subject), it offers the readers an extensive bibliography, which could be used for further research on specific aspects. Copyright © 2005 John Wiley & Sons, Ltd. [source] Very high efficiency solar cell modulesPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 1 2009Allen Barnett Abstract The Very High Efficiency Solar Cell (VHESC) program is developing integrated optical system,PV modules for portable applications that operate at greater than 50% efficiency. We are integrating the optical design with the solar cell design, and have entered previously unoccupied design space. Our approach is driven by proven quantitative models for the solar cell design, the optical design, and the integration of these designs. Optical systems efficiency with an optical efficiency of 93% and solar cell device results under ideal dichroic splitting optics summing to 42·7,±,2·5% are described. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||||||||