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System Configurations (system + configuration)
Selected AbstractsDemand side management for water heating installations in South African commercial buildingsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 4 2001P. G. Rousseau Abstract The largest percentage of the sanitary hot water used in South African buildings is heated by means of direct electrical resistance heaters. This is one of the major contributing factors of the undesirable high morning and afternoon peaks imposed on the national electricity supply grid. Water heating therefore continues to be of concern to ESKOM, the country's only electrical utility company. The so-called in-line water heating system design methodology was developed to address this problem. This paper investigates the potential impact of in-line systems on the national peak electrical demand. A computer simulation model was developed that combines a deterministic mathematical model with a statistical approach in order to predict the diversity factors associated with both the existing and in-line design methodologies. A study was also conducted to estimate the total installed water heating capacity in the national commercial building sector. This figure can be combined with the simulated diversity factor to determine the peak electrical demand. The deterministic model includes the detailed simulation of the hot water storage vessel, the electrical heater and the system control algorithm. The mathematical model for the storage vessel is based on an electrical analogue approach that includes the effects of conduction as well as forced and natural convection. This model was verified extensively with the aid of laboratory measurements and compared with existing storage vessel models. It was found that the new storage vessel model could predict the supply temperature within 2 per cent for a system configuration with the heater in parallel outside the reservoir and within 12 per cent for a configuration with the heater situated inside the reservoir. This compares favourably with existing models found in the literature. The complete simulation based on the statistical approach showed that extensive application of the new design methodology could result in a reduction of approximately 75 MW in the total maximum peak demand imposed on the electricity supply grid in wintertime. This is 58 per cent of the current peak demand due to commercial water heating and 12.5 per cent of the peak load reduction target set by ESKOM until the year 2015. Copyright © 2001 John Wiley & Sons, Ltd. [source] A requirement specification language for configuration dynamics of multiagent systemsINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 3 2004Mehdi Dastani In agent-mediated applications, the system configuration can change because of the creation and the deletion of agents. The behavior of such systems on the one hand depends on the dynamics of the system configuration; on the other hand, behavior of such a system consists of the information dynamics of the system. We discuss configuration and information dynamics of agent-mediated systems and define a requirement language to express properties of those dynamics. A prototypical scenario for an agent-mediated system is discussed and some important requirements for this system are specified. It is shown how these properties can be verified automatically to evaluate system behavior. © 2004 Wiley Periodicals, Inc. [source] Magnetic survey at Venta Icenorum, Caistor St Edmund: Survey strategies and initial resultsARCHAEOLOGICAL PROSPECTION, Issue 4 2009D. Bescoby Abstract This short report summarizes two seasons of magnetic surveying at the Roman town of Venta Icenorum at Caistor St Edmund, Norfolk. Survey strategies have been developed utilizing caesium vapour magnetometers mounted on a wheeled platform with a global positioning system to map former areas of settlement and their immediate hinterlands. The resulting survey system has enabled the rapid collection of high-resolution magnetic data over an area of 30,ha, providing a detailed magnetic map of the former town. Details of the system configuration and survey strategy are described and data from the survey presented. Copyright © 2009 John Wiley & Sons, Ltd. [source] Thermo-Economic Modelling and Optimisation of Fuel Cell Systems,FUEL CELLS, Issue 1 2005F. Marechal Abstract This paper describes and illustrates the application of a methodology for thermo-economic design and optimisation of fuel cell systems. This methodology combines the use of process simulation and process integration techniques to compute thermo-economic performances of fuel cell systems that will be used in a multi-objective optimisation framework. The method allows the generation of integrated fuel cell system configurations and their corresponding optimal operating conditions. It should be used as a preliminary design methodology, allowing the identification of promising system configurations, which would be further analysed. The methodology and the thermo-economic models are described and demonstrated for the design of PEMFC hybrid systems, combining fuel cell and gas turbine technologies. [source] Institutionalization of Party Systems?GOVERNMENT AND OPPOSITION, Issue 2 2007Fluidity among Legislative Parties in Africa's Democracies, Stability Using Sartori's and Mainwaring and Scully's work on consolidation and institutionalization of party systems as touchstones, this article analyses the evolution of party systems with regard to stability and fluidity of legislative party configurations in Africa's democratic states. It examines the key issue of whether there is any stabilization of party systems in Africa today, and if so, under what circumstances such stabilization occurs. This article questions previous studies, arguing that we have not yet sufficiently solved the question of whether party systems as stable interactions exist in Africa. Providing a detailed analysis of elections in Africa's established and emerging democracies, and making a distinction between democratic and undemocratic countries, this study classifies Africa's 21 electoral democracies as fluid, de-stabilized, or stable party systems. A key finding is that institutionalization of these party systems has not occurred over an extended period, but rather, institutionalized party system configurations have been stable from the onset of multiparty elections. Conversely, the other large group of countries with non-institutionalized party systems seems to be perpetually fluid systems despite, in many cases, several successive multiparty elections. [source] A case study of serial-flow car disassembly: Ergonomics, productivity and potential system performanceHUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 4 2007Karolina Kazmierczak A recent European Union (EU) directive increases demands on car recycling. Thus, present craft-type disassembly systems need reconfiguration in order to be more efficient. A line-based system tested in the Netherlands was investigated regarding system performance and ergonomics. The system had reduced performance compared to the design specifications due to such factors as system losses, operator inexperience, and teamwork deficiencies. Operators' peak low back loads were lower than in Swedish craft-type systems. Direct, value-adding work comprised 30% of the workday, compared to about 70% in the Swedish manufacturing industry. Alternative system configurations were simulated and discussed using a novel combination of flow and human simulations. For example, a smaller variation in cycle time implied higher output in number of cars per week and larger operator cumulative loading on the low back. In all models the cumulative load was high compared to the loads previously recorded in assembly work. © 2007 Wiley Periodicals, Inc. Hum Factors Man 17: 331,351, 2007. [source] Root and canal morphology of permanent mandibular molars in a Sudanese populationINTERNATIONAL ENDODONTIC JOURNAL, Issue 10 2007H. A. Ahmed Abstract Aim, To investigate variations in the root canal systems of first and second permanent mandibular molar teeth in a Sudanese population using a clearing technique. Methodology, Two hundred extracted first and second permanent mandibular molars from three cities in the state of Khartoum were studied. Access cavities were prepared and pulp tissue was removed by immersion in 5% sodium hypochlorite under ultrasonication; Indian ink was then injected into the root canal systems assisted by a vacuum applied apically. The teeth were rendered clear by demineralization and immersion in methyl salicylate before evaluation. The following observations were made (i) number of roots and their morphology; (ii) number of root canals per tooth; (iii) number of root canals per root and (iv) root canal configuration. Results, Overall 59% of mandibular first molars had four canals with 3% having a third distolingual root. Seventy-eight per cent of second mandibular molars had two separate flat roots, whilst 10% were C-shaped. The most common canal system configurations were type IV (73%) and type II (14%). Inter-canal communications were more common in the mesial roots. The prevalence of inter-canal communications was 65% in first molars and 49% in second molars. Conclusions, In this sample of Sudanese teeth, 59% of the mandibular first permanent molars had four root canals whilst 10% of the mandibular second molars had C-shaped roots/canals. [source] Performance evaluation of an electricity base load engine cogeneration systemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2010Denilson Boschiero do Espirito Santo Abstract Decentralized electricity production by cogeneration can result in primary energy economy, as these systems operate with a high-energy utilization factor (EUF), producing electricity and recovering energy rejected by the prime mover to meet site thermal demands. Because energy demands in buildings vary with such factors as the hour of the day, level of activity and climatic conditions, cogeneration case studies should consider different system configurations, energy demand profiles and climatic profiles. This paper analyzes an engine cogeneration system as an integrated thermal system by means of a computational simulation program. The simulation takes into account characteristics of the system, characteristics of the pieces of equipment, design choices and parameters, the variability of operating conditions, site energy demand profiles and climatic data to evaluate the performance of the cogeneration plant. Performance evaluation is based on: (i) the EUF, (ii) the exergy efficiency and (iii) primary energy savings analysis. Copyright © 2009 John Wiley & Sons, Ltd. [source] Intersegment handover performance in integrated terrestrial satellite systemsINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 6 2002M. Leo Abstract To achieve a global cellular network, integration among segments offering different coverage (indoor, outdoor and global) must be pursued. Of course, the possibility to hold the call switching among different segments must be guaranteed. Hence, efficient algorithms to perform intersegment handover (ISHO) must be implemented. The paper aims at analysing some ISHO procedures developed in the frame of some European projects and other proposed in the literature, in a scenario with satellite and terrestrial segments interworking to achieve a worldwide cellular coverage. Performance evaluation will be carried out for different system configurations utilizing a dynamic satellite constellation simulator in the time domain. The impact of the distance user-gateway on performance will be addressed. For each procedure, the execution delay and its complementary cumulative distribution have been evaluated for different constellation geometries at different distances from the gateway. Copyright © 2002 John Wiley & Sons, Ltd. [source] Life-Cycle Assessment of Biosolids Processing OptionsJOURNAL OF INDUSTRIAL ECOLOGY, Issue 2 2001Gregory M. Peters Summary Biosolids, also known as sewage sludge, are reusable organic materials separated from sewage during treatment. They can be managed in a variety of ways. Different options for biosolids handling in Sydney, Australia, are compared in this study using life-cycle assessment. Two key comparisons are made: of system scenarios (scenario 1 is local dewatering and lime amendment; scenario 2 is a centralized drying system) and of technologies (thermal drying versus lime amendment). The environmental issues addressed are energy consumption, global warming potential (GWP), and human toxicity potential (HTP). Scenario 2 would consume 24% more energy than scenario 1. This is due to the additional electricity for pumping and particularly the petrochemical methane that supplements biogas in the drier. A centralized system using the same technologies as scenario 1 has approximately the same impacts. The GWP and HTP of the different scenarios do not differ significantly. The assessment of technology choices shows significant differences. The ample supply of endogenous biogas at North Head sewage treatment plant for the drying option allows reductions, relative to the lime-amendment option, of 68% in energy consumption, 45% in GWP, and 23% in HTP. Technology choices have more significant influence on the environmental profile of biosolids processing than does the choice of system configurations. Controlling variables for environmental improvement are the selection of biogas fuel, avoidance of coalsourced electrical energy, minimization of trucking distances, and raising the solids content of biosolids products. [source] Managing service innovation: the need for selectivity rather than ,best practice'NEW TECHNOLOGY, WORK AND EMPLOYMENT, Issue 2 2006Joe Tidd In this paper we contrast the notions of best practice and configurations contingent on environmental conditions. The analysis draws upon our study of 38 UK and 70 US service firms. Four system configurations are identified, and the results provide an opportunity for updating the typologies of services, and suggest that practices and performance are multi-dimensional. [source] Transient behavior of time-between-failures of complex repairable systemsQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 4 2002J. Bert Keats Abstract It is well known for complex repairable systems (with as few as four components), regardless of the time-to-failure (TTF) distribution of each component, that the time-between-failures (TBFs) tends toward the exponential. This is a long-term or ,steady-state' property. Aware of this property, many of those modeling such systems tend to base spares provisioning, maintenance personnel availability and other decisions on an exponential TBFs distribution. Such a policy may suffer serious drawbacks. A non-homogeneous Poisson process (NHPP) accounts for these intervals for some time prior to ,steady-state'. Using computer simulation, the nature of transient TBF behavior is examined. The number of system failures until the exponential TBF assumption is valid is of particular interest. We show, using a number of system configurations and failure and repair distributions, that the transient behavior quickly drives the TBF distribution to the exponential. We feel comfortable with achieving exponential results for the TBF with 30 system failures. This number may be smaller for configurations with more components. However, at this point, we recommend 30 as the systems failure threshold for using the exponential assumption. Copyright © 2002 John Wiley & Sons, Ltd. [source] A new approach for the linearization of a distributed amplifierMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 1 2005D. K. Paul Abstract This paper describes the application of the feedforward linearization technique to a distributed amplifier. The circuit architecture of the distributed amplifier is used in a new way to simplify the feedforward system's configuration. A distributed amplifier using a pseudomorphic HEMT with feedforward linearization based on the new concept is simulated to evaluate the performance and demonstrate the feasibility of achieving broadband linearity. The experimental results for an MIC implementation are also presented as proof of the concept. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 15,17, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20887 [source] | |||||||||||||