844 resultados para System Performance Measures.


Relevância:

80.00% 80.00%

Publicador:

Resumo:

Geotechnical systems, such as landfills, mine tailings storage facilities (TSFs), slopes, and levees, are required to perform safely throughout their service life, which can span from decades for levees to “in perpetuity” for TSFs. The conventional design practice by geotechnical engineers for these systems utilizes the as-built material properties to predict its performance throughout the required service life. The implicit assumption in this design methodology is that the soil properties are stable through time. This is counter to long-term field observations of these systems, particularly where ecological processes such as plant, animal, biological, and geochemical activity are present. Plant roots can densify soil and/or increase hydraulic conductivity, burrowing animals can increase seepage, biological activity can strengthen soil, geochemical processes can increase stiffness, etc. The engineering soil properties naturally change as a stable ecological system is gradually established following initial construction, and these changes alter system performance. This paper presents an integrated perspective and new approach to this issue, considering ecological, geotechnical, and mining demands and constraints. A series of data sets and case histories are utilized to examine these issues and to propose a more integrated design approach, and consideration is given to future opportunities to manage engineered landscapes as ecological systems. We conclude that soil scientists and restoration ecologists must be engaged in initial project design and geotechnical engineers must be active in long-term management during the facility’s service life. For near-surface geotechnical structures in particular, this requires an interdisciplinary perspective and the embracing of soil as a living ecological system rather than an inert construction material.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

In this paper, we investigate half-duplex two-way dual-hop channel state information (CSI)-assisted amplify-and-forward (AF) relaying in the presence of high-power amplifier (HPA) nonlinearity at relays. The expression for the end-to-end signal-to-noise ratio (SNR) is derived as per the modified system model by taking into account the interference caused by relaying scheme and HPA nonlinearity. The system performance of the considered relaying network is evaluated in terms of average symbol error probability (SEP) in Nakagami-$m$ fading channels, by making use of the moment-generating function (MGF) approach. Numerical results are provided and show the effects of several parameters, such as quadrature amplitude modulation (QAM) order, number of relays, HPA parameters, and Nakagami parameter, on performance.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

An ability to quantify the reliability of probabilistic flood inundation predictions is a requirement not only for guiding model development but also for their successful application. Probabilistic flood inundation predictions are usually produced by choosing a method of weighting the model parameter space, but previous study suggests that this choice leads to clear differences in inundation probabilities. This study aims to address the evaluation of the reliability of these probabilistic predictions. However, a lack of an adequate number of observations of flood inundation for a catchment limits the application of conventional methods of evaluating predictive reliability. Consequently, attempts have been made to assess the reliability of probabilistic predictions using multiple observations from a single flood event. Here, a LISFLOOD-FP hydraulic model of an extreme (>1 in 1000 years) flood event in Cockermouth, UK, is constructed and calibrated using multiple performance measures from both peak flood wrack mark data and aerial photography captured post-peak. These measures are used in weighting the parameter space to produce multiple probabilistic predictions for the event. Two methods of assessing the reliability of these probabilistic predictions using limited observations are utilized; an existing method assessing the binary pattern of flooding, and a method developed in this paper to assess predictions of water surface elevation. This study finds that the water surface elevation method has both a better diagnostic and discriminatory ability, but this result is likely to be sensitive to the unknown uncertainties in the upstream boundary condition

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Credit scoring modelling comprises one of the leading formal tools for supporting the granting of credit. Its core objective consists of the generation of a score by means of which potential clients can be listed in the order of the probability of default. A critical factor is whether a credit scoring model is accurate enough in order to provide correct classification of the client as a good or bad payer. In this context the concept of bootstraping aggregating (bagging) arises. The basic idea is to generate multiple classifiers by obtaining the predicted values from the fitted models to several replicated datasets and then combining them into a single predictive classification in order to improve the classification accuracy. In this paper we propose a new bagging-type variant procedure, which we call poly-bagging, consisting of combining predictors over a succession of resamplings. The study is derived by credit scoring modelling. The proposed poly-bagging procedure was applied to some different artificial datasets and to a real granting of credit dataset up to three successions of resamplings. We observed better classification accuracy for the two-bagged and the three-bagged models for all considered setups. These results lead to a strong indication that the poly-bagging approach may promote improvement on the modelling performance measures, while keeping a flexible and straightforward bagging-type structure easy to implement. (C) 2011 Elsevier Ltd. All rights reserved.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

This paper proposes a parallel hardware architecture for image feature detection based on the Scale Invariant Feature Transform algorithm and applied to the Simultaneous Localization And Mapping problem. The work also proposes specific hardware optimizations considered fundamental to embed such a robotic control system on-a-chip. The proposed architecture is completely stand-alone; it reads the input data directly from a CMOS image sensor and provides the results via a field-programmable gate array coupled to an embedded processor. The results may either be used directly in an on-chip application or accessed through an Ethernet connection. The system is able to detect features up to 30 frames per second (320 x 240 pixels) and has accuracy similar to a PC-based implementation. The achieved system performance is at least one order of magnitude better than a PC-based solution, a result achieved by investigating the impact of several hardware-orientated optimizations oil performance, area and accuracy.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The purpose of this article is to present a new method to predict the response variable of an observation in a new cluster for a multilevel logistic regression. The central idea is based on the empirical best estimator for the random effect. Two estimation methods for multilevel model are compared: penalized quasi-likelihood and Gauss-Hermite quadrature. The performance measures for the prediction of the probability for a new cluster observation of the multilevel logistic model in comparison with the usual logistic model are examined through simulations and an application.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The introduction of a new technology High Speed Downlink Packet Access (HSDPA) in the Release 5 of the 3GPP specifications raises the question about its performance capabilities. HSDPA is a promising technology which gives theoretical rates up to 14.4 Mbits. The main objective of this thesis is to discuss the system level performance of HSDPAMainly the thesis exploration focuses on the Packet Scheduler because it is the central entity of the HSDPA design. Due to its function, the Packet Scheduler has a direct impact on the HSDPA system performance. Similarly, it also determines the end user performance, and more specifically the relative performance between the users in the cell.The thesis analyzes several Packet Scheduling algorithms that can optimize the trade-off between system capacity and end user performance for the traffic classes targeted in this thesis.The performance evaluation of the algorithms in the HSDPA system are carried out under computer aided simulations that are assessed under realistic conditions to predict the results as precise on the algorithms efficiency. The simulation of the HSDPA system and the algorithms are coded in C/C++ language

Relevância:

80.00% 80.00%

Publicador:

Resumo:

In Sweden solar irradiation and space heating loads are unevenly distributed over the year. Domestic hot water loads may be nearly constant. Test results on solar collector performance are often reported as yearly output of a certain collector at fixed temperatures, e g 25, 50 and 75 C. These data are not suitable for dimensioning of solar systems, because the actual performance of the collector depends heavily on solar fraction and load distribution over the year.At higher latitudes it is difficult to attain high solar fractions for buildings, due to overheating in summer and small marginal output for added collector area. Solar collectors with internal reflectors offer possibilities to evade overheating problems and deliver more energy at seasons when the load is higher. There are methods for estimating the yearly angular irradiation distribution, but there is a lack of methods for describing the load and the storage in such a way as to enable optical design of season and load adapted collectors.This report describes two methods for estimation of solar system performance with relevance for season and load adaption. Results regarding attainable solar fractions as a function of collector features, load profiles, load levels and storage characteristics are reported. The first method uses monthly collector output data at fixed temperatures from the simulation program MINSUN for estimating solar fractions for different load profiles and load levels. The load level is defined as estimated yearly collector output at constant collector temperature divided be yearly load. This table may examplify the results:CollectorLoadLoadSolar Improvementtypeprofile levelfractionover flat plateFlat plateDHW 75 %59 %Load adaptedDHW 75 %66 %12 %Flat plateSpace heating 50 %22 %Load adaptedSpace heating 50 %28 %29 %The second method utilises simulations with one-hour timesteps for collectors connected to a simplified storage and a variable load. Collector output, optical and thermal losses, heat overproduction, load level and storage temperature are presented as functions of solar incidence angles. These data are suitable for optical design of load adapted solar collectors. Results for a Stockholm location indicate that a solar combisystem with a solar fraction around 30 % should have collectors that reduce heat production at solar heights above 30 degrees and have optimum efficiency for solar heights between 8 and 30 degrees.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

In a northern European climate a typical solar combisystem for a single family house normally saves between 10 and 30 % of the auxiliary energy needed for space heating and domestic water heating. It is considered uneconomical to dimension systems for higher energy savings. Overheating problems may also occur. One way of avoiding these problems is to use a collector that is designed so that it has a low optical efficiency in summer, when the solar elevation is high and the load is small, and a high optical efficiency in early spring and late fall when the solar elevation is low and the load is large.The study investigates the possibilities to design the system and, in particular, the collector optics, in order to match the system performance with the yearly variations of the heating load and the solar irradiation. It seems possible to design practically viable load adapted collectors, and to use them for whole roofs ( 40 m2) without causing more overheating stress on the system than with a standard 10 m2 system. The load adapted collectors collect roughly as much energy per unit area as flat plate collectors, but they may be produced at a lower cost due to lower material costs. There is an additional potential for a cost reduction since it is possible to design the load adapted collector for low stagnation temperatures making it possible to use less expensive materials. One and the same collector design is suitable for a wide range of system sizes and roof inclinations. The report contains descriptions of optimized collector designs, properties of realistic collectors, and results of calculations of system output, stagnation performance and cost performance. Appropriate computer tools for optical analysis, optimization of collectors in systems and a very fast simulation model have been developed.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Test method for integrated solar- biomass systems - Long term prediction trough short term measurementsSP Technical Research Institute of Sweden and SERC, Dalarna University have in cooperation developed a test method for integrated solar and biomass systems. The test method is performed under six days including two summer days, two winter days and two spring/autumn days true to real weather conditions and loads for a single family house. The aim of the test method is to get information about a Combisystem’s annual performance and operation throughout a short term test. Seven different solar Combisystems have been tested within the project together with a pellet boiler without solar collectors. In addition to that a comparative testing has been performed at the two laboratories at SP and at SERC on the same Combisystem. The test method developed within the project has been proved to withstand the aim of the project, which is to be able to compare the performance between the systems. The test method is also suitable for identification of possible operation problems so they can be taken care of and consequently improves the system.The project and the system testing reveal that it is in general favorable to combine biomass pellets with solar heating. Pellet boilers has normally a low performance during the summer period but combined with a solar collector the boiler can be switch off during this period. There are however big differences in performance between the tested. The efficiency of the pellet boiler is highly dependent of the operating conditions and elements like heat losses from the system, system configuration and control strategy have great influence of the performance of the system and the emissions. On the other hand, the performance and the size of the solar collectors have a minor effect on the overall system performance. There is obviously a big potential for improvement of the system´s performance and the developed test method is an essential way to implement this perfection.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

This paper studies the influence of hydraulics and control of thermal storage in systems combined with solar thermal and heat pump for the production of warm water and space heating in dwellings. A reference air source heat pump system with flat plate collectors connected to a combistore was defined and modeled together with the IEA SHC Task 44 / HPP Annex 38 (T44A38) “Solar and Heat Pump Systems” boundary conditions of Strasbourg climate and SFH45 building. Three and four pipe connections as well as use of internal and external heat exchangers for DHW preparation were investigated as well as sensor height for charging of the DHW zone in the store. The temperature in this zone was varied to ensure the same DHW comfort was achieved in all cases. The results show that the four pipe connection results in 9% improvement in SPF compared to three pipe and that the external heat exchanger for DHW preparation leads to a 2% improvement compared to the reference case. Additionally the sensor height for charging the DHW zone of the store should not be too low, otherwise system performance is adversely affected

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Governmental acquisitions, in Brazil, must be proceeded, as a rule, by means of licitation. Though this principle became constitutional rule only from 1988's Constitution, its existence in Brazilian legal system retraces century XV: by that time, the Filipinas Ordinations ruled it in one only law article. Since then, several rules of law had been incorporated to the Brazilian governmental acquirement system, especially during century XX, hardening the procedures and restricting public manager's discritionarity. Current governmental acquirement system was instituted by the Law nº 8,666/1993, which, however, did not disrupt previous system: with few innovations and more restrictions, it only copied the instruments in the system of the Decree nº 2,300/1986 and previous ones. In its original text, Law nº 8,666/1993 had three licitation procedures for acquisitions - concorrência, tomada de preços, convite - and the exceptional procedures - dispensa and inexigibilidade. Once revealed itself a rigid system, several measures were implemented in order to make it more flexible, having for objectives celerity and price reduction, from discrete alterations of articles of laws to the creation of pregão as a new licitation procedure - initially, there was only the pregão presencial, proceeded face to face - and no longer, the pregão eletrônico, proceeded through web. This research focuses the analysis of the impact of the rigidity / flexibility on Government acquirement system. Despite specialized literature, studies carried through for governmental agencies and state publicity praises the results reached with the use of the pregão eletrônico, the analyses that lead to such conclusion are based on questionable premises. The studies on the efficiency of the pregão eletrônico restrict this concept to its economic dimension, interpreting it as costs reduction. Beyond, the methodology of analysis of this cost reduction has for reference hypothetical values which are also defined by random standards. Here it is, therefore, the objective of this study: to analyze, from the perception of the public managers, the relation between flexibility or rigidity of a procedure and its efficiency, under a multidimensional perspective - taking into consideration, beyond the prices gotten for objects, the time of transaction, the quality of objects and the security of the procedure. From the answers to the questionnaires applied to licitation managers and to members of licitations permanent commissions it was raisen three kinds of information: descriptive data concerning to the ordinal or nominal variables, extracted from the analysis of the objective fields of the questionnaire; not-structuralized, extracted directly from the subjective fields of the questionnaire; e, finally, treated data, extracted from the hypotheses formulated in the research and statistically analyzed. The reflections on the information allowed concluding that the acquirement governmental procedures flexibility extends its efficiency. Restricted the analysis to the pregão eletrônico, it is concluded that it is more efficient under the economic and time perspectives, in relation to the classic procedures; however, under the perspective of the security it does not significantly differs from those; under the qualitative perspective, it is less efficient than the classic procedures, implying in the reduction of the quality of acquired or contracted objects.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Este estudo avalia a influência do desenvolvimento tecnológico sobre o social, a partir das atividades produtivas desenvolvidas na unidade agroindustrial Recanto lI, no município de Catolé do Rocha, com o apoio da Incubadora Tecnológica de Campina Grande - ITCG, e o Programa de Estudos e Ações no Semi-Árido Paraibano da Universidade Federal de Campina Grande - PEASAlUFCG. Os problemas sociais no semi-árido surgiram por condições ambientais adversas e se intensificaram pela falta de políticas públicas adequadas à educação e ao desenvolvimento da região. O problema é expresso pela seguinte indagação: Qual a influência entre o desenvolvimento tecnológico e o desenvolvimento social gerados a partir da atividade produtiva da Incubadora de Campina Grande, em Campina Grande, Paraíba? A relevância deste trabalho vem da pretensão em colaborar para o estudo da relação entre desenvolvimento tecnológico e social, numa tentativa de tornar inteligível a necessidade de educação e inovação tecnológica para o desenvolvimento social, principalmente em países não desenvolvidos. Vem também da utilidade para a formulação de políticas públicas e estratégias de desenvolvimento tecnológico, identificando ações e medidas de desempenho, voltadas ao diagnóstico da contribuição das incubadoras tecnológicas para o bem-estar da sociedade. O referencial teórico foi composto pela análise da função das racionalidades dos diversos agentes sociais e de sua contribuição para as interações sociais, além da análise das realidades culturais da sociedade empresariada, do Estado e das incubadoras tecnológicas. A metodologia se utilizou da pesquisa descritiva e explicativa, de campo, documental, bibliográfica e estudo de caso. O universo foram as pessoas que compõem a ITCG e a amostra foram o diretor da Incubadora, o cientista da UFCG e o líder comunitário de Recanto lI. Os sujeitos da pesquisa confundem-se com a amostra. A coleta de dados se deu por meio da literatura sobre a temática e de inserções no campo de estudo. O tratamento de dados se utilizou da análise qualitativa do fenômeno. As principais limitações do método consistiram na coleta, no tratamento dos dados, e na utilização do estudo de caso, com possibilidade de compreensão tendenciosa do fenômeno estudado. O referencial prático apresenta o resultados da pesquisa, avaliando-os por meio da comparação com o referencial teórico estudado. Tem-se como resultados que a ITCG agiu articulando os grupos e traduzindo as realidades culturais de cada agente em prol do desenvolvimento de comunidades agroindustriais em situação de risco social, devido à problemática da seca. A ITCG atuou como alfabetizadora social ensinando aos agentes sociais os códigos culturais dos demais grupos. As desigualdades que existiam entre o cientista e o sertanejo, aprofundadas pelo vexatório histórico de escravidão do homem do campo no nordeste brasileiro, foram minimizadas pela educação dada pelo próprio cientista. A Universidade contribuiu para a redução do analfabetismo ambiental, onde o meio ambiente era tido como o principal rival do homem do sertão. O Estado, quando atua em parceria com os demais agentes sociais consegue, manter-se como o principal instrumento dos cidadãos para controlar a globalização em função de seus valores e interesses. Na ITCG o ambiente de incubação é educacional, onde os novos empreendedores são postos em contato com a realidade cultural do empresariado, do Estado e de outras comunidades da sociedade, seguindo modelos meramente educacionais. Como conclusão tem-se que a trajetória dos cidadãos de Recanto II - de escravos a exportadores - foi baseada em dois grandes tesouros, a família e areligião. O mérito da ITCG foi compreender, respeitar e preservar a realidade cultural de Recanto 11 e incentivar a interação social com outras realidades culturais capazes de gerar desenvolvimento naquela região. A saúde, o desenvolvimento infantil, a segurança, a habitação foram conquistas de Recanto 11. Como sugestão tem-se que as políticas públicas deveriam reproduzir este ambiente de desenvolvimento para todos os cidadãos brasileiros em situação de risco social, utilizando-se da família como base para interações sociais fluidas e harmônicas entre os diversos agentes sociais.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Este trabalho tem o objetivo de analisar. explorar e descrever as características culturais do BANESTES SI A - Banco do Estado do Espírito Santo. que influenciam na sua capacidade de adequar-se à forma de atuação do sistema financeiro privado, concluindo se estas características favorecem ou dificultam sua adaptabilidade. O desenvolvimento da dissertação se dá com a pesquisa bibliográfica referente ao arcabouço teórico da cultura organizacional e da evolução do Sistema Financeiro Nacional, de uma investigação documental para se levantar os dados e descrever o perfil atual do BANESTES e de uma pesquisa de campo. com entrevistas e observações. A pesquisa realizada para a elaboração do trabalho é de natureza qualitativa, do tipo exploratório. descritiva e avaliativa. O modo de investigação é o do estudo de caso histórico-organizacional, com observação participante. Os principais fundamentos que compõem o trabalho são extraídos da pesquisa histórica, das teorias convencionais de administração, da base teórica da cultura organizacional, da organização em aprendizagem e da transformação organizacional. A análise e observações estão descritas ao final da dissertação, mais precisamente no quinto capítulo. A bibliografia compõe um quadro de todos os autores e documentos pesquisados que oferecem suporte à dissertação.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

This research evaluated the quality of the management of Brazilian stock funds on the period from January 1997 to October 2006. The analysis was based on the Modern Portfolio Theory measures of performance. In addition, this research evaluated the relevance of the performance measures The sample with 21 funds was extracted from the 126 largest Brasilian stock options funds because they were the only with quotas on the whole period. The monthly mean rate of return and the following indexes were calculated: total return, mean monthly return, Jensen Index, Treynor Index, Sharpe Index, Sortino Index, Market Timing and the Mean Quadratic Error. The initial analysis showed that the funds in the sample had different objectives and limitations. To make valuable comparisons, the ANBID (National Association of Investment Banks) categories were used to classify the funds. The measured results were ranked. The positions of the funds on the rankings based on the mean monthly return and the indexes of Jensen, Treynor, Sortino and Sharpe were similar. All of the ten ACTIVE funds of this research were above the benchmark (IBOVESPA index) in the measures above. Based on the CAPM, the managers of these funds got superior performance because they might have compiled the available information in a superior way. The six funds belonging to the ANBID classification of INDEXED got the first six positions in the ranking based on the Mean Quadratic Error. None of the researched funds have shown market timing skills to move the beta of their portfolios in the right direction to take the benefit of the market movements, at the significance level of 5%.