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Stability and prediction of 100-m breaststroke performance during the careers of elite swimmers

Costa, M.J.; Marinho, D.A.; Reis, V.M.; Silva, A.J.; Bragada, José A.; Barbosa, Tiago M.
Fonte: Norwegian School of Sports Science Publicador: Norwegian School of Sports Science
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.03%
The aim of this study was to track and analyze the 100-m Breaststroke performance stability throughout elite swimmer’s career. 35 Portuguese male top-50 were analyzed for seven consecutive seasons between 12 and 18 years old. Best performances were collected from ranking tables. Longitudinal assessment was performed based on two approaches: (i) mean stability was analyzed by descriptive statistics and ANOVA repeated measures for each season followed by a post-hoc test (Bonferroni test), (ii) normative stability was analyzed with self-correlation (Malina, 2001) and the Cohen’s Kappa tracking index (Landis and Koch, 1977). There was a 100-m Breaststroke performance enhancement from children to adult age. The overall career performance prediction was low. The change from 13 to 14 years can be a milestone, where the ability to predict the final swimmer’s performance level strongly increases.

100m and 200m front crawl performance prediction based on anthropometric and physiological measurements

Reis, V.M.; Silva, A.J.; Carneiro, André Luiz; Marinho, D.A.; Novaes, G.; Barbosa, Tiago M.
Fonte: International Federation of Sports Medicine Publicador: International Federation of Sports Medicine
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.08%
Background: The identification of the variables that are able to predict swimming performance is one of the main purposes of the “swimming science” community. Research question: The aims of the study were: (i) to compare the anthropometric and physiological profiles of 100m and 200m front crawl swimmers and; (ii) to identify anthropometric and physiological variables that account for the prediction of the swimming performance at the 100m and 200m front crawl events. Methods: Twenty-six male swimmers were divided in two groups (12 for 100m group and 14 to 200m group). The swimmers’ personal best performance for the 100m and the 200m front crawl was converted to FINA points. The subjects performed a graded swimming test and an all-out test (100 or 200m maximal swims) in different days, in which physiological measures were evaluated. Forward step-by-step linear regression models were computed to predict swimming performance. The subjects’ performances (season best and all-out test) were taken as dependent variables. The age, physiological and anthropometric measures were selected as independent variables. Results: Anthropometric and physiological profiles of 100 and 200m swimmers are different and the mean oxygen uptake during exercise combined with training experience may explain 200m front crawl best season performance with a high precision (≈2% error). The models computed were able to predict from 44 % (i.e. 200m all-out bout) to 61 % (i.e. 200m season best) swimming performance. Predictive power of the models was less accurate in the 100m event (error > 10%). Conclusions: The authors conclude that the extent to which the physiological and anthropometric variables combine to predict performance probable is group-specific.

Desenvolvimento de modelos para predição de desempenho de programas paralelos MPI. ; Development of Performance Prediction Models for MPI Parallel Programs

Laine, Jean Marcos
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 27/01/2003 PT
Relevância na Pesquisa
56.14%
Existem muitos fatores capazes de influenciar o desempenho de um programa paralelo MPI (Message Passing Interface). Dentre esses fatores, podemos citar a quantidade de dados processados, o número de nós envolvidos na solução do problema, as características da rede de interconexão, o tipo de switch utilizado, entre outros. Por isso, realizar predições de desempenho sobre programas paralelos que utilizam passagem de mensagem não é uma tarefa trivial. Com o intuito de modelar e predizer o comportamento dos programas citados anteriormente, nosso trabalho foi desenvolvido baseado em uma metodologia de análise e predição de desempenho de programas paralelos MPI. Inicialmente, propomos um modelo gráfico, denominado DP*Graph+, para representar o código das aplicações. Em seguida, desenvolvemos modelos analíticos, utilizando técnicas de ajuste de curvas, para representar o comportamento das estruturas de repetição compostas por primitivas de comunicação e/ou computação local. Além disso, elaboramos modelos para predizer o comportamento de aplicações do tipo mestre/escravo. Durante o desenvolvimento das atividades de análise e predição de desempenho, implementamos algumas funções para automatizar tarefas e facilitar nosso trabalho. Por último...

Análise comparativa de modelos de previsão de desempenho de pavimentos flexíveis

Nascimento, Deise Menezes
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 01/06/2005 PT
Relevância na Pesquisa
46.14%
Os modelos de previsão de desempenho de pavimentos são importantes ferramentas utilizadas pelos sistemas de gerência, essenciais para o planejamento das atividades de manutenção e reabilitação, assim como para a estimativa dos recursos necessários para a preservação das rodovias. Este trabalho tem por objetivo comparar modelos de desempenho de pavimentos, desenvolvidos por análises empíricas e empírico-mecanísticas, que predizem a evolução da condição de pavimentos flexíveis, ao longo do tempo e/ou tráfego acumulado. Os modelos de desempenho analisados foram desenvolvidos por pesquisadores e órgãos rodoviários brasileiros e internacionais, inclusive os modelos de deterioração utilizados pelo programa computacional de gerência de pavimentos desenvolvido pelo Banco Mundial, o HDM–4 (Highway Development and Management). A pesquisa está baseada na comparação do desempenho real de seções de pavimentos rodoviários, obtido a partir da base de dados dos experimentos LTPP (Long-Term Pavement Performance) do FHWA (Federal Highway Administration), com o comportamento previsto pelos modelos de desempenho desenvolvidos por Queiroz (1981), Paterson (1987), Marcon (1996) e Yshiba (2003). Neste trabalho, a análise do comportamento das seções de teste LTPP-FHWA é feita utilizando-se uma programação fatorial que...

Avaliação e predição de desempenho de programas paralelos em redes de estações de trabalho.; Parallel program performance analysis and prediction on NOW systems.

Li, Kuan Ching
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 25/10/2001 PT
Relevância na Pesquisa
56.12%
Processamento distribuído tem sido utilizado amplamente para melhorar o desempenho de aplicações com alta demanda computacional. Diferentes arquiteturas e topologias distribuídas têm sido pesquisadas e utilizadas para prover o alto desempenho, proporcionando assim o recurso necessário para a exploração do paralelismo presente nas aplicações. A facilidade para construir sistemas computacionais de alto desempenho a partir de estações de trabalho interligadas através de redes de alta velocidade, aliada ao custo relativamente baixo e ao crescente avanço da tecnologia de circuitos integrados, possibilita a montagem de redes de computadores de baixo custo para a execução de aplicações paralelas. Devido a este fato, diversos sistemas de software para redes de estações têm sido desenvolvidos, visando a integração dos componentes distribuídos para a agregação das suas capacidades de processamento. No entanto, o processo de desenvolvimento de aplicações é complexo e difícil, dado que são necessários identificar o paralelismo existente nestas aplicações, e providenciar as comunicações necessárias. Neste trabalho, é apresentada uma proposta de metodologia de análise e predição de desempenho de programas paralelos...

Desenvolvimento de modelos de previsão de desempenho de pavimentos asfálticos com base em dados da rede de rodovias do Estado da Bahia; Development of performance prediction models for asphalt pavements based on data from the highway network of the State of Bahia, Brazil

Soncim, Sérgio Pacífico
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 28/06/2011 PT
Relevância na Pesquisa
56.21%
O objetivo desta tese de doutorado foi desenvolver modelos de previsão de desempenho de pavimentos asfálticos para a malha rodoviária do Estado da Bahia. Os modelos de desempenho foram desenvolvidos para pavimentos em concreto asfáltico usinado a quente e em tratamento superficial duplo. Foram utilizadas informações de um banco de dados de gerência de rodovias do DERBA, coletados em 2004, e foram coletados dados complementares de irregularidade longitudinal em 2009, após o desenvolvimento de um planejamento fatorial específico para essa finalidade. Foram utilizadas duas formas de análise estatística dos dados para avaliar a significância dos fatores e definir os parâmetros dos modelos de desempenho: a Análise Exploratória de Dados (AED) e a Análise da Variância (ANOVA). Os fatores considerados foram a idade do pavimento, o tráfego e a pluviometria e os resultados da análise exploratória de dados corroboraram os resultados encontrados pela análise da variância, tanto em relação aos efeitos dos fatores como das interações. Os modelos de previsão do desempenho foram desenvolvidos para as variáveis dependentes Índice de Condição do Pavimento Flexível (ICPF) e Área Total de Trincas (ATT), para os pavimentos em concreto asfáltico usinado a quente...

Proposta de um sistema de modelagem e predição analitica de desempenho para uma plataforma de processamento paralelo; Proposal of a performance modeling and analytical prediction system for a parallel processing system

Roberto Hirochi Herai
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 16/12/2005 PT
Relevância na Pesquisa
56.01%
A predição de desempenho é um importante mecanismo para avaliar a utilização de recursos e estimar o tempo de execução de aplicações em sistemas paralelos. Este trabalho apresenta uma ferramenta que permite criar modelos que representam características da aplicação e dos computadores utilizados para processá-la. Tais modelos são combinados para gerar um modelo de desempenho mais abrangente, cuja análise permite obter estimativas de tempo de execução que contemplem fatores de atraso tais como operações aritméticas sobre diferentes tipos de dados e efeitos de contenção, causados por concorrência. As estimativas podem ser geradas em poucos segundos e permitem analisar o impacto causado na aplicação pela utilização de diferentes configurações do sistema de processamento paralelo. A ferramenta foi implementada para um sistema de processamento paralelo baseado em Java, chamado JoiN, e ela mostrou ser possível obter estimativas satisfatórias de tempos de execução para diversos tipos de aplicações paralelas; Performance prediction is an important mechanism to evaluate the use of resources and predict the execution time of applications in parallel systems. This work presents a tool for the creation of models that represent applications and computers characteristics. Such models are combined to generate a performance model...

Darrieus wind turbine performance prediction: computational modeling

Melício, Rui; Mendes, Victor; Figueiredo, João; Reis, Heitor
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Parte de Livro
ENG
Relevância na Pesquisa
66.02%
The Vertical Axis Wind Turbines Darrieus is facing a rapid installations growth due to the interest for a decentralizing generation. The Darrieus aerodynamic behavior analysis is a hard computational task. This paper starts by offering an insight into the Darrieus wind turbines performance prediction and proposes an algorithm based on the Multiple Streamtube modeling as a prediction approach in order to have an admissible handing in an Internet of things environment.

Relationships between episodic memory performance prediction and sociodemographic variables among healthy older adults

Oliveira,Glaucia Martins de; Cachioni,Meire; Falcão,Deusivania; Batistoni,Samila; Lopes,Andrea; Guimarães,Vanessa; Lima-Silva,Thais Bento; Neri,Anita Liberalesso; Yassuda,Mônica Sanches
Fonte: Associação de Neurologia Cognitiva e do Comportamento Publicador: Associação de Neurologia Cognitiva e do Comportamento
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2015 EN
Relevância na Pesquisa
56.2%
Previous studies have suggested that performance prediction, an aspect of metamemory, may be associated with objective performance on memory tasks. OBJECTIVE: The objective of the study was to describe memory prediction before performing an episodic memory task, in community-dwelling older adults, stratified by sex, age group and educational level. Additionally, the association between predicted and objective performance on a memory task was investigated. METHODS: The study was based on data from 359 participants in the FIBRA study carried out at Ermelino Matarazzo, São Paulo. Memory prediction was assessed by posing the question: "If someone showed you a sheet with drawings of 10 pictures to observe for 30 seconds, how many pictures do you think you could remember without seeing the sheet?". Memory performance was assessed by the memorization of 10 black and white pictures from the Brief Cognitive Screening Battery (BCSB). RESULTS: No differences were found between men and women, nor for age group and educational level, in memory performance prediction before carrying out the memory task. There was a modest association (rho=0.11, p=0.041) between memory prediction and performance in immediate memory. On multivariate linear regression analyses...

Integrating neural network and numerical simulation for production performance prediction of low permeability reservoir

Yang, Qingjun; Zhang, Shulin; Fei, Qi
Fonte: Taylor & Francis Publicador: Taylor & Francis
Tipo: Artigo de Revista Científica
Publicado em //2005 EN
Relevância na Pesquisa
55.99%
It is difficult to predict the production performance of low permeability fractured oil reservoirs. This is because complicated factors such as geological and engineering factors affect well production performance. This paper presents a methodology to predict well production performance in the Hanq oil field, which is a low permeability fractured reservoir. Integration of neural network with numerical simulation is employed. First we study the regularity of fluid flow and oil displacement mechanism by injection well group numerical simulation and analysis of production performance. Then we form the expert knowledge affecting production performance. The neural networks based on expert knowledge are trained using production data. This method will play an important role in future waterflood management and the design of recovery strategy for the Hanq oil field.; Qingjun Yang, Shulin Zhang and Qi Fei

Model-driven performance prediction of distributed real-time embedded defence systems

Falkner, K.; Chiprianov, V.; Falkner, N.; Szabo, C.; Hill, J.; Puddy, G.; Fraser, D.; Johnston, A.; Rieckmann, M.; Wallis, A.
Fonte: IEEE; USA Publicador: IEEE; USA
Tipo: Conference paper
Publicado em //2013 EN
Relevância na Pesquisa
46.11%
Autonomous defence systems are typically characterised by hard constraints on space, weight and power. These constraints have a strong impact on the non-functional properties, and performance, of the final system. System execution modelling tools permit early prediction of the performance of model driven systems, however the focus to date has been on understanding the performance of a model rather than determining if it meets performance requirements, and subsequently carrying out analysis to reveal the causes of any requirement violations. In this paper, we propose an integrated approach to performance prediction of model-driven distributed real time embedded defence systems. Our architectural prototyping system supports a scenario-driven experimental platform for evaluating model suitability within a set of deployment and real-time performance constraints. We present an overview of our performance prediction system, demonstrating the integration of modelling, execution and visualisation, and discuss a case study to illustrate our approach.; Katrina Falkner, Vanea Chiprianov, Nickolas J.G. Falkner, Claudia Szabo, James H. Hill, Gavin Puddy, Dan Fraser, Adrian Johnston, Marianne Rieckmann, Andrew Wallis

Architectural support for model-driven performance prediction of distributed real-time embedded systems of systems

Chiprianov, V.; Falkner, K.; Szabo, C.; Puddy, G.
Fonte: Springer International Publishing Publicador: Springer International Publishing
Tipo: Conference paper
Publicado em //2014 EN
Relevância na Pesquisa
46.11%
Systems of systems (SoS) are large-scale systems composed of complex systems with difficult to predict emergent properties. One of the most significant challenges in the engineering of such systems is how to predict their non-functional properties such as performance, and more specifically, how to model non-functional properties when the overall system functionality is not available. In this paper, we define an approach to SoS performance prediction based on the modelling of system interactions and their impacts. We adopt an Event Driven Architecture to support this modelling, as it allows for more realistic and flexible performance simulation, which enables more accurate performance prediction. We introduce a generic architecture and present its instantiation in a software architecture for the performance prediction of defence SoS. Our architecture allows for loose coupling, interoperability, and adaptability and facilitates sustainable evolution of the performance model of the SoS.; Vanea Chiprianov, Katrina Falkner, Claudia Szabo, Gavin Puddy

Performance prediction from a computer hardware description

Cox, Lyle Ashton
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Relatório Formato: 24 p. : ill. ; 28 cm.
EN_US
Relevância na Pesquisa
55.91%
Today's computers are among the most complex man made systems in existence today. How can we make our designs not only more precise, but make these systems more accurately and cost effectively achieve their goals? We have begun to rely upon computer aided design techniques. The use of these techniques often commences not with the statement of the system goals, but rather with the specification of an architecture and a logic technology. In view of the high costs of computer development, we should be quite confident that our architecture/technology combination is capable of meeting the system requirements before we proceed to more detailed design phases. The entire system design process must be integrated, and include performance prediction and verification techniques. This design process should be reflected in a single description language. A methodology for accomplishing this goal capable of employing many existing design practices is discussed here. (Author); Prepared for: Chief of Naval Research; Arlington, VA 22217. -- Cover.; http://archive.org/details/performancepredi00coxl; NOOO1480WR00054

Pavement performance prediction using adaptive logic networks

Nawaiseh, Moh'd Y
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.16%
Pavement performance is one of the most important components of the pavement management system. Prediction of the future performance of a pavement section is important in programming maintenance and rehabilitation needs. Models for predicting pavement performance have been developed on the basis of traffic and age. The purpose of this research is to extend the use of a relatively new approach to performance prediction in pavement performance modeling using adaptive logic networks (ALN). Adaptive logic networks have recently emerged as an effective alternative to artificial neural networks for machine learning tasks. ^ The ALN predictive methodology is applicable to a wide variety of contexts including prediction of roughness based indices, composite rating indices and/or individual pavement distresses. The ALN program requires key information about a pavement section, including the current distress indexes, pavement age, climate region, traffic and other variables to predict yearly performance values into the future. ^ This research investigates the effect of different learning rates of the ALN in pavement performance modeling. It can be used at both the network and project level for predicting the long term performance of a road network. Results indicate that the ALN approach is well suited for pavement performance prediction modeling and shows a significant improvement over the results obtained from other artificial intelligence approaches. ^

An Improved Methodology for Individualized Performance Prediction of Sleep-Deprived Individuals with the Two-Process Model

Rajaraman, Srinivasan; Gribok, Andrei V.; Wesensten, Nancy J.; Balkin, Thomas J.; Reifman, Jaques
Fonte: Associated Professional Sleep Societies, LLC Publicador: Associated Professional Sleep Societies, LLC
Tipo: Artigo de Revista Científica
Publicado em 01/10/2009 EN
Relevância na Pesquisa
56.06%
We present a method based on the two-process model of sleep regulation for developing individualized biomathematical models that predict performance impairment for individuals subjected to total sleep loss. This new method advances our previous work in two important ways. First, it enables model customization to start as soon as the first performance measurement from an individual becomes available. This was achieved by optimally combining the performance information obtained from the individual's performance measurements with a priori performance information using a Bayesian framework, while retaining the strategy of transforming the nonlinear optimization problem of finding the optimal estimates of the two-process model parameters into a series of linear optimization problems. Second, by taking advantage of the linear representation of the two-process model, this new method enables the analytical computation of statistically based measures of reliability for the model predictions in the form of prediction intervals.

Corporate Evidential Decision Making in Performance Prediction Domains

Buchner, Alex G.; Dubitzky, Werner; Schuster, Alfons; Lopes, Philippe; O'Donoghue, Peter G.; Hughes, John G.; Bell, David A.; Adamson, Kenny; White, John A.; Anderson, John M. C. C.; Mulvenna, Maurice D.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 06/02/2013
Relevância na Pesquisa
46.06%
Performance prediction or forecasting sporting outcomes involves a great deal of insight into the particular area one is dealing with, and a considerable amount of intuition about the factors that bear on such outcomes and performances. The mathematical Theory of Evidence offers representation formalisms which grant experts a high degree of freedom when expressing their subjective beliefs in the context of decision-making situations like performance prediction. Furthermore, this reasoning framework incorporates a powerful mechanism to systematically pool the decisions made by individual subject matter experts. The idea behind such a combination of knowledge is to improve the competence (quality) of the overall decision-making process. This paper reports on a performance prediction experiment carried out during the European Football Championship in 1996. Relying on the knowledge of four predictors, Evidence Theory was used to forecast the final scores of all 31 matches. The results of this empirical study are very encouraging.; Comment: Appears in Proceedings of the Thirteenth Conference on Uncertainty in Artificial Intelligence (UAI1997)

A CHAID Based Performance Prediction Model in Educational Data Mining

Ramaswami, M.; Bhaskaran, R.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 05/02/2010
Relevância na Pesquisa
46.14%
The performance in higher secondary school education in India is a turning point in the academic lives of all students. As this academic performance is influenced by many factors, it is essential to develop predictive data mining model for students' performance so as to identify the slow learners and study the influence of the dominant factors on their academic performance. In the present investigation, a survey cum experimental methodology was adopted to generate a database and it was constructed from a primary and a secondary source. While the primary data was collected from the regular students, the secondary data was gathered from the school and office of the Chief Educational Officer (CEO). A total of 1000 datasets of the year 2006 from five different schools in three different districts of Tamilnadu were collected. The raw data was preprocessed in terms of filling up missing values, transforming values in one form into another and relevant attribute/ variable selection. As a result, we had 772 student records, which were used for CHAID prediction model construction. A set of prediction rules were extracted from CHIAD prediction model and the efficiency of the generated CHIAD prediction model was found. The accuracy of the present model was compared with other model and it has been found to be satisfactory.; Comment: International Journal of Computer Science Issues...

Model and analysis of performance prediction through the many-varied analysis of data methodology: an empirical study of the electric energy sector; Modelo e análise de previsão de desempenho pela metodologia de análise multivariada de dados: um estudo empírico do setor de energia elétrica

Andrade Pereira, Antônio Fernando Oliveira; UFPEC - Recife - PE; Pedrosa Júnior, Carlos; UFPB - João Pessoa - PB; Ramos, Evandro José Santos; FCA - Salvador - BA
Fonte: UFSC Publicador: UFSC
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Formato: application/pdf
Publicado em 01/01/2006 POR
Relevância na Pesquisa
56.06%
The present work aims at empirically estimating an equation with the simultaneous use of the performance prediction of the Brazilian energy companies. The study involves 40 companies, using their financial statements of 2003 found at the Securities and Exchange Commission and at São Paulo Stock Exchange. The methodology adopted was composed of the many-varied data analysis techniques added to factor analysis and discriminating analysis. The software Statical Package for the Social Sciences (SPSS) version 10.0 was used. In the theoretical background the many-varied techniques were exhaustively scrutinized as well as some papers recently presented in conferences. The results obtained demonstrated the efficacy of the model for the performance prediction, thus contributing for the analysis of credit undertaken by the rating companies.; Este trabalho tem como objetivo estimar empiricamente uma equação com corte simultâneo de previsão de desempenho das empresas do setor energético no Brasil. O estudo utiliza-se de uma amostra de 40 empresas, através do levantamento das demonstrações contábeis de 2003, junto à Comissão de Valores Mobiliários e à Bolsa de Valores de São Paulo. A metodologia adotada foi composta de técnicas de análise multivariada...

Coefficent of performance prediction by a polynomial model of absorption heat transformer

Escobedo-Trujillo,B.A.; Alaffita-Hernández,F.A.; Colorado,D.; Siqueiros,J.
Fonte: UAM, Unidad Iztapalapa, División de Ciencias Básicas e Ingeniería Publicador: UAM, Unidad Iztapalapa, División de Ciencias Básicas e Ingeniería
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
Relevância na Pesquisa
46.05%
A polynomial model is developed to predict the coefficient of performance of a water purification process integrated to an absorption heat transformer. The range of the coefficient of performance operations was from 0.21 to 0.39. This model used: inlet temperature in the generator which comes from the absorber, outlet temperature in the absorber that comes from the generator, inlet temperature in the absorber that comes from the generator, water-lithium bromide solution inlet concentration in the generator that comes from the absorber and the pressure in the absorber and generator. A polynomial model is presented in order to obtain coefficient of performance prediction with a determination coefficient of 0.91919. Level surfaces of the coefficient of performance against the inlet variables for the polynomial model and residual analysis were presented with the aim of validating the model. This work has the purpose of providing faster and simpler solutions instead of the complex equations used for the analysis of the heat transformer in order to obtain accurate coefficient of performance prediction. The operation variable with the greater contribution of determination coefficient is presented.

A model to predict the performance of roadheaders based on the Rock Mass Brittleness Index

Ebrahimabadi,A.; Goshtasbi,K.; Shahriar,K.; Cheraghi Seifabad,M.
Fonte: Journal of the Southern African Institute of Mining and Metallurgy Publicador: Journal of the Southern African Institute of Mining and Metallurgy
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2011 EN
Relevância na Pesquisa
56.06%
Roadheaders are very versatile excavation machines used in tunnelling, mine development, and mine production for soft to medium strength rock formations. Performance prediction is an important factor for successful roadheader application and generally deals with machine selection, production rate and bit consumption. Among many different parameters, brittleness is also one of the material properties related to breakage characteristics and can be used as a cuttability parameter from a mechanical excavation point of view. The main objective of the research study is to contribute the brittleness of rock excavated to construct a new empirical equation for predicting the performance of roadheaders in different material and operational conditions. In this regard, a new performance prediction model for medium duty roadheaders based on a brittleness index (BI) is presented. In this study, rock mass brittleness index (RMBI) is defined in order to investigate the influence of BI on roadheader performance. RMBI is an index which can be used to relate the intact and rock mass characteristics to machine performance. Results demonstrated that RMBI is highly correlated to instantaneous cutting rate (ICR) (R²=0.94). Moreover, through the further analysis and normalization...