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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Traffic Accident Prediction Model Implementation in Traffic Safety Management

Wen, Keyao January 2009 (has links)
As one of the highest fatalities causes, traffic accidents and collisions always requires a large amounteffort to be reduced or prevented from occur. Traffic safety management routines therefore always needefficient and effective implementation due to the variations of traffic, especially from trafficengineering point of view apart from driver education.Traffic Accident Prediction Model, considered as one of the handy tool of traffic safety management,has become of well followed with interested. Although it is believed that traffic accidents are mostlycaused by human factors, these accident prediction models would help from traffic engineering point ofview to enlarge the traffic safety level of road segments. This thesis is aiming for providing a guidelineof the accident prediction model implementation in traffic safety management, regarding to trafficengineering field. Discussion about how this prediction models should merge into the existing routinesand how well these models would perform would be given. As well, cost benefit analysis of theimplementation would be at the end of this thesis. Meanwhile, a practical field study would bepresented in order to show the procedures of the implementation of traffic accident prediction model.The field study is about this commercial model set SafeNET, from TRL Limited UK, implemented inRoad Safety Audit procedures combined with microscopic simulation tool. Detailed processing andinput and output data will be given accompany with the countermeasures for accident frequencyreduction finalization.
32

Information Theoretic Evaluation of Change Prediction Models for Large-Scale Software

Askari, Mina January 2006 (has links)
During software development and maintenance, as a software system evolves, changes are made and bugs are fixed in various files. In large-scale systems, file histories are stored in software repositories, such as CVS, which record modifications. By studying software repositories, we can learn about open source software development rocesses. Knowing where these changes will happen in advance, gives power to managers and developers to concentrate on those files. Due to the unpredictability in software development process, proposing an accurate change prediction model is hard. It is even harder to compare different models with the actual model of changes that is not available. <br /><br /> In this thesis, we first analyze the information generated during the development process, which can be obtained through mining the software repositories. We observe that the change data follows a Zipf distribution and exhibits self-similarity. Based on the extracted data, we then develop three probabilistic models to predict which files will have changes or bugs. One purpose of creating these models is to rank the files of the software that are most susceptible to having faults. <br /><br /> The first model is Maximum Likelihood Estimation (MLE), which simply counts the number of events i. e. , changes or bugs that occur in to each file, and normalizes the counts to compute a probability distribution. The second model is Reflexive Exponential Decay (RED), in which we postulate that the predictive rate of modification in a file is incremented by any modification to that file and decays exponentially. The result of a new bug occurring to that file is a new exponential effect added to the first one. The third model is called RED Co-Changes (REDCC). With each modification to a given file, the REDCC model not only increments its predictive rate, but also increments the rate for other files that are related to the given file through previous co-changes. <br /><br /> We then present an information-theoretic approach to evaluate the performance of different prediction models. In this approach, the closeness of model distribution to the actual unknown probability distribution of the system is measured using cross entropy. We evaluate our prediction models empirically using the proposed information-theoretic approach for six large open source systems. Based on this evaluation, we observe that of our three prediction models, the REDCC model predicts the distribution that is closest to the actual distribution for all the studied systems.
33

Use of Advanced Techniques to Estimate Zonal Level Safety Planning Models and Examine their Temporal Transferability

Hadayeghi, Alireza 24 September 2009 (has links)
Historically, the traditional planning process has not given much attention to the road safety evaluation of development plans. To make an informed, defensible, and proactive choice between alternative plans and their safety implications, it is necessary to have a procedure for estimating and evaluating safety performance. A procedure is required for examining the influence of the urban network development on road safety, and in particular, determining the effects of the many variables that affect safety in urban planning. Safety planning models can provide a decision-support tool that facilitates the assessment of the safety implications of alternative network plans. The first objective of this research study is to develop safety planning models that are consistent with the regional models commonly used for urban transportation planning. Geographically weighted Poisson regression (GWPR), full-Bayesian semiparametric additive (FBSA), and traditional generalized linear modelling (GLM) techniques are used to develop the models. The study evaluates how well each model is able to handle spatial variations in the relationship between collision explanatory variables and the number of collisions in a zone. The evaluation uses measures of goodness of fit (GOF) and finds that the GWPR and FBSA models perform much better than the conventional GLM approach. There is little difference between the GOF values for the FBSA and GWPR models. The second objective of this research study is to examine the temporal transferability of the safety planning models and alternative updating methods. The updating procedures examine the Bayesian approach and application of calibration factors. The results show that the models are not temporally transferable in a strict statistical sense. However, relative measures of transferability indicate that the transferred models yield useful information in the application context. The results also show that the updated safety planning models using the Bayesian approach predict the number of collisions better than the calibration factor procedure.
34

Use of Advanced Techniques to Estimate Zonal Level Safety Planning Models and Examine their Temporal Transferability

Hadayeghi, Alireza 24 September 2009 (has links)
Historically, the traditional planning process has not given much attention to the road safety evaluation of development plans. To make an informed, defensible, and proactive choice between alternative plans and their safety implications, it is necessary to have a procedure for estimating and evaluating safety performance. A procedure is required for examining the influence of the urban network development on road safety, and in particular, determining the effects of the many variables that affect safety in urban planning. Safety planning models can provide a decision-support tool that facilitates the assessment of the safety implications of alternative network plans. The first objective of this research study is to develop safety planning models that are consistent with the regional models commonly used for urban transportation planning. Geographically weighted Poisson regression (GWPR), full-Bayesian semiparametric additive (FBSA), and traditional generalized linear modelling (GLM) techniques are used to develop the models. The study evaluates how well each model is able to handle spatial variations in the relationship between collision explanatory variables and the number of collisions in a zone. The evaluation uses measures of goodness of fit (GOF) and finds that the GWPR and FBSA models perform much better than the conventional GLM approach. There is little difference between the GOF values for the FBSA and GWPR models. The second objective of this research study is to examine the temporal transferability of the safety planning models and alternative updating methods. The updating procedures examine the Bayesian approach and application of calibration factors. The results show that the models are not temporally transferable in a strict statistical sense. However, relative measures of transferability indicate that the transferred models yield useful information in the application context. The results also show that the updated safety planning models using the Bayesian approach predict the number of collisions better than the calibration factor procedure.
35

Systémy finančních ukazatelů / Systems of financial indicators

MONDEKOVÁ, Kristýna January 2015 (has links)
This thesis deals with systems of financial indicators. The theoretical part contains the individual systems which are described and explained on the basis of literature. The practical part is divide into three parts. First part contains individual analyses of indicators. The second part deals with a pyramid decomposition of return on equity which is compared in time and space. The last part is the practical application of the rating and default models to the selected firm. There are summarized and evaluated results of the practical part in conclusion.
36

Formatos e técnicas de modelos de previsão de acidentes de trânsito

Boffo, Gabriela Holz January 2011 (has links)
A ampliação acelerada da demanda por transporte, mais especificamente pelo transporte rodoviário, tem provocado um aumento expressivo no número de acidentes de trânsito nesse ambiente. Consequentemente, a redução dos acidentes de trânsito tem sido um grande desafio para os pesquisadores e gestores da área rodoviária. Porém, os acidentes de trânsito são eventos complexos se considerados os diversos fatores que podem influenciá-los. Dentro desse contexto esta dissertação apresenta um estudo de modelos de previsão de acidentes, que podem ser utilizados para a avaliação do potencial de segurança em determinados locais, identificação e classificação de localidades perigosas ou com propensão a acidentes e avaliação da eficácia de medidas de melhoria da segurança. Nessa dissertação é apresentado um levantamento teórico e metodológico dos modelos de previsão de acidentes, identificando as principais variáveis adotadas bem como as técnicas utilizadas. Para cada modelo revisado foram verificadas as principais diferenças e limitações, e ainda, a análise das variáveis mais influentes presentes nesses modelos. Após, é feita uma comparação de duas abordagens distintas para estimar modelos de previsão de acidentes. A primeira consiste em estimar a ocorrência de acidentes em segmentos da via com as mudanças de características dos elementos de infraestrutura. O segundo relaciona a frequência de acidentes para um único elemento de infraestrutura da via, chamado na literatura internacional de entidade (ex: interseção, curva, tangente, etc.), com base apenas na variável relacionada ao volume de tráfego. O estudo baseado na comparação dessas duas abordagens para a previsão de acidentes revelou que a utilização do volume de tráfego como única variável independente apresenta resultados semelhantes ou até melhores que os modelos baseados em diversos elementos de infraestrutura da rodovia. / The enlargement and the accelerated development of transportation systems, more specifically the land system, have caused the number of road accidents to increase significantly. Therefore, the reduction of road accidents has been a great challenge for researchers and managers in the field of land transportation. However, considering the various factors that may influence them, road accidents are complex events. In this context, this paper presents a study of accident prediction models that can be used to assess the safety potential in certain locations, identify and rank dangerous locations or areas prone to accidents and evaluate the effectiveness of safety improvement measures. Initially, a theoretical and methodological review of accident prediction models is presented, and both the main variables adopted and the methodologies employed are identified. The main differences between all models reviewed and their limitations are presented, and the most influential variables are analyzed. In a second moment, a comparison of two different accident prediction methods is performed. The first method consists in estimating the occurrence of accidents in road sections with changes in the characteristics of infrastructure elements. The second one relates the frequency of accidents based on a single infrastructure element (intersection, curve, tangent, etc.) based on traffic volume only. The study based on the comparison of these two methods found that the use of traffic volume as the only independent variable yields similar or even better results than the models based on various road infrastructure elements.
37

Avaliação de desempenho de recapeamentos asfálticos com camada intemediária de geotêxtil submetidos à solicitação por simulador de tráfego / Performance evaluation of asphalt overlays containing intermediate layer of geotextile submitted to traffic simulator

Fiorin, Marcelo Menezes January 2009 (has links)
Esta dissertação apresenta os resultados e análises do monitoramento de um recapeamento asfáltico executado com camada intermediária de geotêxtil. A pista experimental vem sendo solicitada desde 1999, em uma pesquisa que se encontra na sua terceira fase, atingindo 1.103.885 ciclos de carga de 100 kN aplicados. Nessa última fase de estudo o tráfego foi aplicado entre Setembro de 2008 e Fevereiro de 2009, totalizando 121.685 ciclos de carga de eixo de 100 kN. A pista foi dividida em três regiões, sendo empregado em duas delas geotêxteis impregnados com asfalto. Durante o período de estudo foram monitorados parâmetros de resposta estrutural, através de medidas de deflexões e bacias defletométricas, parâmetros de comportamento, através de medidas de deformações permanentes e mapeamento de trincas, e por fim parâmetros ambientais, através das medidas de temperatura do ar e precipitações. Foram também aplicados modelos de previsão de desempenho para o caso de reflexões de trincas. O monitoramento do trincamento na pista mostrou que as regiões com geotêxtil tiveram melhor desempenho quando comparadas à região sem camada intermediária. O comprimento de trincas no final do estudo foi de 764 cm na região sem camada intermediária, 328 cm na região com geotêxtil G150 e 554 cm na região com geotêxtil G150 TF. Foram extraídos corpos de prova da pista, sobre algumas trincas, de modo a se visualizar o modo de desenvolvimento do trincamento, e também para buscar se identificar onde ocorreu trincamento por reflexão. Não foi possível extrair CPs de todas as trincas face a proximidade das mesmas e das dimensões da sonda rotativa, porém do material retirado observou-se ocorrência de trincamento por reflexão, trincamento por fadiga e também trincamento conhecido como top-down cracking (TDC). Os resultados evidenciam que a inclusão de geotêxteis como camada de absorção de tensões aumenta significativamente a vida de recapeamentos asfálticos executados sobre pavimentos trincados. / This dissertation presents the results of the monitoring and analysis of an overlay executed with intermediate geotextile layer. The experimental track has been requested since 1999, in a research that is in its third phase, reaching 1.103.885 cycles of 100 kN axle load applied. In this last phase of the study, the traffic was applied between September 2008 and February 2009, totaling 121.685 cycles of 100 kN axle load. The track is divided into three regions, two of them uses geotextiles impregnated with asphalt. During the study period were monitored parameters of structural response, by means of deflections and basins, parameters of behavior, by means of permanent deformation and mapping of cracks, and finally environmental parameters, through the measures of air temperature and rainfall. Models were also applied to predict the performance of the overlay. The monitoring of cracking showed that regions with geotextile had improved performance when compared to the region without intermediate layer. The length of cracks at the end of the study was 764 cm in the region without intermediate layer, 328 cm in the region with geotextile G150 and 554 cm in the region with geotextile G150 TF. Samples were extracted from the track to see how the cracking was developed and also to identify where there was reflective cracking. On the material removed was observed occurrence of reflective cracking, fatigue cracking and also top-down cracking (TDC). The results show that geotextiles increases the life of concrete asphaltic overlays.
38

Predikce finanční tísně podniku / Financial distress prediction of company

MAŇASOVÁ, Helena January 2014 (has links)
The theoretical part of this master thesis deals with creation and solution of financial distress and analysing classification models. In the practical part I defined own methods for financial distress prediction of company using discriminant analysis and logistic regression.
39

DESENVOLVIMENTO DE MODELOS DE PREVISÃO DE DESEMPENHO A PARTIR DA IMPLANTAÇÃO DE TRECHOS MONITORADOS NA REGIÃO DE SANTA MARIA - RS / DEVELOPMENT PERFORMANCE PREDICTION MODELS BY IMPLANTATION OF MONITORED STRETCHES IN THE REGION OF SANTA MARIA, RS

Santos, Mauricio Silveira dos 16 July 2015 (has links)
In a country with continental dimensions like Brazil, road infrastructure that provides a displacement with comfort and safety is extremely important, once it is from these roads that the majority of supplies and people moves daily to distant regions. Is through appropriate management of corrective floors and measurements taken at the correct times that these highways provides safety and comfort to users in their displacement. One way to perform this management properly is making use of performance prediction models that makes the manager can predict the appearance of defects and the necessity of performing maintenance, providing financial resources required for repairs. Thus, the objective of this research is to monitor three highway stretches implemented in the region of Santa Maria - RS, checking their functional and structural performance in order to assist in the development of performance prediction models. To achieving the study, tests were performed at predetermined periods: Sand Patch, British Pendulum, Roughness, Rutting analysis, Distress identification and Deflections Basin Survey by Benkelman Beam and Falling Weight Deflectometer (FWD) at Roraima Avenue (restoration stretch), Hélvio Basso Avenue and Quartéis Intersection (new highway stretches). In these tests, quantitative and classifying counts of vehicles were made in order to find the number of equivalent demand of standard axis through the FEC calculation by AASHTO and USACE methodology. With that was obtained in all 34 performance prediction models for Avenues Roraima and Hélvio Basso (17 - AASHTO and 17 - USACE). No models have been developed for Quartéis Intersection once it is at the beginning of monitoring. In addition to performance prediction models, performance evaluations were carried out of three sections monitored the mediated that it were requested by the traffic, and found that the Roraima Avenue had the highest deflection values, IGG and cracked area. The Quartéis Intersection had the highest values of rutting. Back Analysis were performed by BAKFAA software to obtain resilient modulus in all layers of pavements studied and, in general, met values coherent with those studied in the literature. It was also made structural analysis by AEMC/SisPAv (2009) software in order to find the estimated durability in the highway stretches. The Roraima Avenue despite being an old stretch and present the highest amount of early distress, was the one that had the highest prediction of durability between the three analysed sections. Furthermore, structural analysis was performed for Roraima Avenue, by standard DNER PRO 011/1979, once it is a restored pavement, it was found that this stretch is expected five years and ten months of durability. Therefore, monitoring and obtaining performance prediction models are extremely important for the proper management of pavements. / Em um país com dimensões continentais como o Brasil, infraestrutura de rodovias que proporcione um deslocamento com conforto e segurança é extremamente importante, uma vez que é a partir destas rodovias que a grande maioria dos insumos e das pessoas se desloca diariamente para regiões distantes. É por meio da gerência adequada dos pavimentos e medidas corretivas realizadas nos tempos corretos, que estas rodovias fornecem aos usuários segurança e conforto nos seus deslocamentos. Uma forma de realizar esta gerência de maneira adequada é fazendo uso de modelos de previsão de desempenho, que fazem com que o gestor possa prever de forma antecipada o aparecimento de defeitos e a necessidade da realização de manutenções, disponibilizando, assim, recursos financeiros necessários para as obras de intervenções. Com isso, o objetivo desta pesquisa é realizar o monitoramento de três trechos implantados na região de Santa Maria RS, verificando seus desempenhos funcionais e estruturais de modo a subsidiar a construção de modelos de previsão de desempenho. Para a concretização do estudo foi realizado, em períodos pré-determinados, ensaios de Mancha de Areia, Pêndulo Britânico, Irregularidade Longitudinal, Afundamento em Trilha de Roda, Levantamento Visual de Defeitos e Levantamento de Bacia de Deflexões através da Viga Benkelman e Falling Weight Deflectometer (FWD) na Avenida Roraima (trecho de restauração), Avenida Hélvio Basso e no Trevo dos Quartéis (trechos novos). Além destes ensaios, foram feitas contagens quantitativas e classificatórias dos veículos que solicitavam os trechos, com a intenção de encontrar o número de solicitações equivalentes do eixo padrão através dos cálculos de FEC pela metodologia AASHTO e USACE. Com isso, obteve-se no total 34 modelos de previsão de desempenho para as Avenidas Roraima e Hélvio Basso (17 AASHTO e 17 USACE). Não foram desenvolvidos modelos para o Trevo dos Quartéis, uma vez que o mesmo está em início de monitoramento. Além dos modelos de previsão de desempenho, foram realizadas avaliações do desempenho dos três trechos monitorados à mediada que o mesmo era solicitado pelo tráfego, sendo verificado que a Avenida Roraima apresentou os maiores valores de deflexão, IGG e Área Trincada. Já o Trevo dos Quartéis apresentou os maiores valores de ATR. Foram realizadas retroanálises pelo software BAKFAA para obtenção de módulo de resiliência em todas as camadas dos pavimentos estudados e, de forma geral, encontrou-se valores coerentes com os estudados na literatura. Fez-se, também, análises estruturais através do software AEMC/SisPAv (2009), a fim de encontrar a estimativa de durabilidade dos trechos. A Avenida Roraima apesar de ser um trecho antigo e apresentar a maior quantidade de defeitos prematuramente, foi a que teve a maior previsão de durabilidade entre os três trechos. Além disso, realizou-se a análise estrutural da Avenida Roraima pela norma DNER PRO 011/1979, uma vez que se trata de uma restauração de um pavimento e constatou-se que este trecho tem previsão de durabilidade de cinco anos e dez meses. Assim, o monitoramento e obtenção de modelos de previsão de desempenho são de suma importância para a boa gerência dos pavimentos.
40

Avaliação de desempenho de recapeamentos asfálticos com camada intemediária de geotêxtil submetidos à solicitação por simulador de tráfego / Performance evaluation of asphalt overlays containing intermediate layer of geotextile submitted to traffic simulator

Fiorin, Marcelo Menezes January 2009 (has links)
Esta dissertação apresenta os resultados e análises do monitoramento de um recapeamento asfáltico executado com camada intermediária de geotêxtil. A pista experimental vem sendo solicitada desde 1999, em uma pesquisa que se encontra na sua terceira fase, atingindo 1.103.885 ciclos de carga de 100 kN aplicados. Nessa última fase de estudo o tráfego foi aplicado entre Setembro de 2008 e Fevereiro de 2009, totalizando 121.685 ciclos de carga de eixo de 100 kN. A pista foi dividida em três regiões, sendo empregado em duas delas geotêxteis impregnados com asfalto. Durante o período de estudo foram monitorados parâmetros de resposta estrutural, através de medidas de deflexões e bacias defletométricas, parâmetros de comportamento, através de medidas de deformações permanentes e mapeamento de trincas, e por fim parâmetros ambientais, através das medidas de temperatura do ar e precipitações. Foram também aplicados modelos de previsão de desempenho para o caso de reflexões de trincas. O monitoramento do trincamento na pista mostrou que as regiões com geotêxtil tiveram melhor desempenho quando comparadas à região sem camada intermediária. O comprimento de trincas no final do estudo foi de 764 cm na região sem camada intermediária, 328 cm na região com geotêxtil G150 e 554 cm na região com geotêxtil G150 TF. Foram extraídos corpos de prova da pista, sobre algumas trincas, de modo a se visualizar o modo de desenvolvimento do trincamento, e também para buscar se identificar onde ocorreu trincamento por reflexão. Não foi possível extrair CPs de todas as trincas face a proximidade das mesmas e das dimensões da sonda rotativa, porém do material retirado observou-se ocorrência de trincamento por reflexão, trincamento por fadiga e também trincamento conhecido como top-down cracking (TDC). Os resultados evidenciam que a inclusão de geotêxteis como camada de absorção de tensões aumenta significativamente a vida de recapeamentos asfálticos executados sobre pavimentos trincados. / This dissertation presents the results of the monitoring and analysis of an overlay executed with intermediate geotextile layer. The experimental track has been requested since 1999, in a research that is in its third phase, reaching 1.103.885 cycles of 100 kN axle load applied. In this last phase of the study, the traffic was applied between September 2008 and February 2009, totaling 121.685 cycles of 100 kN axle load. The track is divided into three regions, two of them uses geotextiles impregnated with asphalt. During the study period were monitored parameters of structural response, by means of deflections and basins, parameters of behavior, by means of permanent deformation and mapping of cracks, and finally environmental parameters, through the measures of air temperature and rainfall. Models were also applied to predict the performance of the overlay. The monitoring of cracking showed that regions with geotextile had improved performance when compared to the region without intermediate layer. The length of cracks at the end of the study was 764 cm in the region without intermediate layer, 328 cm in the region with geotextile G150 and 554 cm in the region with geotextile G150 TF. Samples were extracted from the track to see how the cracking was developed and also to identify where there was reflective cracking. On the material removed was observed occurrence of reflective cracking, fatigue cracking and also top-down cracking (TDC). The results show that geotextiles increases the life of concrete asphaltic overlays.

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