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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

Mathematical models for scientific terminology and their applications in the classification of publications / Mokslinės terminijos matematiniai modeliai ir jų taikymas leidinių klasifikavime

Balys, Vaidas 11 November 2009 (has links)
The dissertation considers the problem of automatic classification of scientific publications. The problem is addressed by using probabilistic methods of the discriminant analysis. The main goal of the dissertation is to create constructive classification methods that would allow to take into consideration specificity of scientific publication text. The dissertation consists of Introduction, 3 chapters, Conclusions, References, list of author's publications, and one Appendix. The introduction reveals the investigated problem, importance of the thesis and the object of research and describes the purpose and tasks of the paper, research methodology, scientific novelty, the practical significance of results examined in the paper and defended statements. The introduction ends in presenting the author’s publications on the subject of the defended dissertation, offering the material of made presentations in conferences and defining the structure of the dissertation. Chapter 1 presents a detailed mathematical formulation of the considered problem, reviews scientific papers on the subject, and analyses a few popular classification algorithms that in Chapter 3 are compared to the ones proposed in this paper. Chapter 2 develops the probabilistic model for scientific terminology distribution over texts, discusses special cases of the model under specific assumptions on forms of terminology relations, suggests the model identification procedures, and formulates constructive scientific... [to full text] / Disertacijoje nagrinėjamas mokslo publikacijų automatinio klasifikavimo uždavinys. Šis uždavinys sprendžiamas taikant tikimybinius diskriminantinės analizės metodus. Pagrindinis darbo tikslas - sukurti konstruktyvius klasifikavimo metodus, kurie leistų atsižvelgti į mokslo publikacijų tekstų specifiką. Disertaciją sudaro įvadas, trys pagrindiniai skyriai, rezultatų apibendrinimas, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašai ir vienas priedas. Įvadiniame skyriuje aptariama tiriamoji problema, darbo aktualumas, aprašomas tyrimų objektas, formuluojamas pagrindinis darbo tikslas bei uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, pasiektų rezultatų praktinė reikšmė, ginamieji teiginiai. Įvado pabaigoje pristatomos disertacijos tema autoriaus paskelbtos publikacijos ir pranešimai konferencijose bei disertacijos struktūra. Pirmajame skyriuje matematiškai apibrėžtas ir detalizuotas sprendžiamas uždavinys, pateikta analitinė kitų autorių darbų apžvalga. Pasirinkti ir išanalizuoti keli populiarūs klasifikavimo algoritmai, kurie eksperimentinėje darbo dalyje lyginti su autoriaus pasiūlytaisiais. Antrajame skyriuje sudarytas mokslo terminijos pasiskirstymo tekstuose tikimybinis modelis, išskirti atskiri atvejai, galiojant įvestoms prielaidoms apie terminų tarpusavio sąryšių formas, pasiūlytos modelio identifikavimo procedūros bei suformuluoti konstruktyvūs mokslo publikacijų klasifikavimo algoritmai. Trečiajame skyriuje pateikti pagrindiniai... [toliau žr. visą tekstą]
32

Comparação da capacidade preditiva de modelos heterocedásticos através da estimação do value-at-risk / Predictive ability comparison of heteroskedastic models by estimating the value-at-risk

Amaro, Raphael Silveira 22 July 2016 (has links)
In an increasingly competitive economic environment, as in the current global context, risk management becomes essential for the survival of companies and investment portfolio managers. Both companies and managers need to have a model that can be able to quantify the risks inherent in their investments in the best possible way in order to guide them in making decisions to get the highest expected return on their investments. Currently, there are several heterogeneous models which seek to quantify risk, making the choice of a particular model very complex. In order to confront and find models that can serve, efficiently, to the quantification of risk, the objective of this research is to compare the predictive ability of five models of conditional heteroskedasticity by estimating the Value-at-Risk, assuming eight different statistical probability distributions, for the series of financial ratios of the capital market of the five largest emerging countries: Brazil, Russia, India, China and South Africa, in the period between February 26, 2001 and December 31, 2015. For this goal was achieved, were held predictions of Value-at-Risk for 50 steps ahead, for all competing models in the study, with adjustment of parameters at every step. Since all the forecasts have been computed for every steps forward, it was possible to compare predictive ability of competing models studied by means of some loss functions. The evidences suggests that heterocedastic Component GARCH is preferable, to make predictions of Value-at-Risk, to all other competing models, however the distribution of statistical probability that this model uses interferes too much in the results of forecasts obtained by it. The data for each financial index studied showed to adapt themselves to a particular different type of probability density function, not reflecting a distribution which can be considered superior to all other. Thus, the results do not provide a single and ideal tool for use in the risk measurement, of generalized form, for all capital markets of emerging countries studied, only provide specific tools to be used in each financial index individually. The results found can be used for the purposes previously described or to elaborate statistical formulas that combine different models estimated in order to get better volatilities forecast measures so that it can measure, more precisely, the market risks. / Em um ambiente econômico cada vez mais competitivo, como é no atual contexto mundial, a gestão de risco torna-se indispensável para a sobrevivência de empresas e de gestores de carteiras de investimento. Tanto as empresas quanto os gestores precisam de um modelo que seja capaz de quantificar os riscos inerentes aos seus investimentos financeiros da melhor maneira possível, de forma a orientá-los na tomada de decisões para que obtenham o maior retorno esperado de seus investimentos. Atualmente, existem inúmeros modelos heterogêneos que buscam quantificar riscos, tornando a escolha de um determinado modelo bastante complexa. Com o intuito de confrontar e encontrar modelos que possam servir, de forma eficiente, à quantificação de riscos, o objetivo desta pesquisa é o de comparar a capacidade preditiva de cinco modelos de heterocedasticidade condicional através da estimação do Value-at-Risk, levando em consideração oito distribuições de probabilidade estatística diferentes, para as séries de índices financeiros do mercado de capitais dos cinco maiores países emergentes: Brasil, Rússia, Índia, China e África do Sul, no período compreendido entre 26 de fevereiro de 2001 e 31 de dezembro de 2015. Para alcançar tal objetivo, realizaram-se previsões do Value-at-Risk para 50 passos à frente, em todos os modelos concorrentes em estudo, com reajuste dos parâmetros a cada passo. Uma vez que todas as previsões foram computadas para todos os passos à frente, foi possível realizar a comparação da capacidade preditiva dos modelos concorrentes estudados por meio de determinadas funções de perda específicas. As evidências encontradas sugerem que o modelo heterocedástico Component GARCH é preferível, para realizar previsões do Value-at-Risk, a todos os outros modelos concorrentes, porém a distribuição de probabilidade estatística que este modelo utiliza interfere demasiadamente nos resultados das previsões obtidas por ele. Os dados de cada índice financeiro estudado mostraram-se adequar-se a um determinado tipo de função de densidade de probabilidade diferente, não refletindo uma distribuição que possa ser considerada superior a todas as outras. Deste modo, os resultados encontrados não oferecem uma ferramenta única e ideal para ser utilizada na mensuração de risco, de forma generalizada, para todos os mercados de capitais dos países emergentes estudados, apenas fornecem ferramentas pontuais para serem utilizadas em cada índice financeiro de forma individual. Os resultados obtidos podem servir para os fins descritos anteriormente ou para elaborar fórmulas estatísticas que combinem diferentes modelos estimados com a finalidade de obter melhores medidas de previsão de volatilidades para que se possa mensurar, de forma mais precisa, os riscos de mercado.
33

Distribuição espacial e plano de amostragem seqüencial de ácaros fitófagos na cultura da seringueira [Hevea brasiliensis (Wild. Ex Adr. de Juss.) Müell.Arg.] /

Martins, Gustavo Luís Mamoré. January 2008 (has links)
Resumo: O objetivo deste trabalho foi estudar a distribuição espacial e desenvolver um plano de amostragem seqüencial para os ácaros Calacarus heveae Feres e Tenuipalpus heveae Baker, na cultura da seringueira. Para isso, a área experimental, com 1000 plantas do clone RRIM 600, foi dividida em 100 parcelas de dez plantas cada uma. As amostragens foram realizadas de dezembro de 2007 a junho de 2008 em intervalos de aproximadamente dez dias. Em cada data foram amostradas duas plantas por parcela, coletando-se de cada uma, uma extremidade de ramo com aproximadamente 30 cm de comprimento. No laboratório, os ácaros foram avaliados com o uso de lupa de bolso de 20X de aumento, em seis folíolos por parcela, sendo três de cada ramo. A contagem de C. heveae foi realizada em duas áreas de 1 cm2 na página superior dos folíolos. Para T. heveae a contagem foi realizada em duas áreas de 1 cm2 na página inferior dos folíolos, sendo uma sobre a nervura principal e outra sobre a nervura lateral. Para medir a distribuição espacial foram calculados os índices de dispersão: razão variância média (I), índice de Morisita ( d I ), coeficiente de Green (Cx) e expoente k da distribuição Binomial Negativa. O plano de amostragem seqüencial foi desenvolvido de acordo com o Teste Seqüencial da Razão de Verossimilhança (TSRV). Foi pré-estabelecido o valor de 0,10 para e que representam o Erro Tipo I e Erro Tipo II, respectivamente. O nível de controle adotado foi de 17% de infestação para C. heveae e 39% de infestação para T. heveae. Foi determinada a Curva Característica de Operação [CO(p)] e a Curva do Tamanho Máximo Esperado de Amostra [Ep(n)]. A partir dos resultados obtidos, verificou-se que C. heveae e T. heveae apresentam distribuição agregada na cultura da seringueira, se ajustando ao modelo de distribuição Binomial Negativa. No plano de amostragem seqüencial de C. heveae foram... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objective of this work was to study the spatial distribution and developing a sequential sampling plan for the mites Calacarus heveae Feres and Tenuipalpus heveae Baker on rubber tree crop. For this reason, the experimental area, with 1000 plants of RRIM 600 clone, was divided into 100 plots of ten plants each. Samples were taken from December 2007 to June of 2008 at intervals of about ten days. On each date were sampled two plants per plot, capturing of each, one end of class with about 30 cm in length. In the laboratory, the mites were evaluated using a magnifying glass, pocket of 20X to increase in six leaves per plot, three of each branch. The counting of C. heveae was conducted in two areas of 1 cm2 in the upper leaflets. For T. heveae the counting was done in two areas of 1 cm2 in the lower leaflets, one on the main vein and one vein on the side. To measure the spatial distribution were calculated rates of dispersal: variance/mean relationship (I), index of Morisita (I ), coefficient of Green (Cx) and k exponent of negative binomial distribution. The sequential sampling plan was developed in accordance with the Sequential Test of the Likelihood Ratio (TSRV). First was pre-established value of 0.10 for and representing the Error Type I and Type II error, respectively. The level of control adopted was 17% of infestation for C. heveae and 39% of infestation for T. heveae. It was determined the Operation Characteristic Curves [CO(p)] and Curve of the High Expected Sample Size [Ep(n)]. These results and as the indices of distribution used was found that C. heveae and T. heveae present distribution of rubber tree crop in the aggregate, is adjusting to the Negative Binomial distribution model. For the sequential sampling plan of C. heveae were obtained two lines: an upper (S1 = 17,0106 + 2,0949 N), from which control is recommended, and another lower (S0 = -17,0106 + 2,0949 N), until... (Complete abstract click electronic access below) / Orientador: Marineide Rosa Vieira / Coorientador: Jose Carlos Barbosa / Banca: Geraldo Papa / Banca: Carlos Amadeu Leite de Oliveira / Mestre
34

Modelo estocástico para estimação da produtividade de soja no Estado de São Paulo utilizando simulação normal bivariada / Sthocastic model to estimate the soybean productivity in the State of São Paulo through bivaried normal simulation

Thomas Newton Martin 08 February 2007 (has links)
A disponibilidade de recursos, tanto de ordem financeira quanto de mão-de-obra, é escassa. Sendo assim, deve-se incentivar o planejamento regional que minimize a utilização de recursos. A previsão de safra por intermédio de técnicas de modelagem deve ser realizada anteriormente com base nas características regionais, indicando assim as diretrizes básicas da pesquisa, bem como o planejamento regional. Dessa forma, os objetivos deste trabalho são: (i) caracterizar as variáveis do clima por intermédio de diferentes distribuições de probabilidade; (ii) verificar a homogeneidade espacial e temporal para as variáveis do clima; (iii) utilizar a distribuição normal bivariada para simular parâmetros utilizados na estimação de produtividade da cultura de soja; e (iv) propor um modelo para estimar a ordem de magnitude da produtividade potencial (dependente da interação genótipo, temperatura, radiação fotossinteticamente ativa e fotoperíodo) e da produtividade deplecionada (dependente da podutividade potencial, da chuva e do armazenamento de água no solo) de grãos de soja, baseados nos valores diários de temperatura, insolação e chuva, para o estado de São Paulo. As variáveis utilizadas neste estudo foram: temperatura média, insolação, radiação solar fotossinteticamente ativa e precipitação pluvial, em escala diária, obtidas em 27 estações localizadas no Estado de São Paulo e seis estações localizadas em Estados vizinhos. Primeiramente, verificou-se a aderência das variáveis a cinco distribuições de probabilidade (normal, log-normal, exponencial, gama e weibull), por intermédio do teste de Kolmogorov-Smirnov. Verificou-se a homogeneidade espacial e temporal dos dados por intermédio da análise de agrupamento pelo método de Ward e estimou-se o tamanho de amostra (número de anos) para as variáveis. A geração de números aleatórios foi realizada por intermédio do método Monte Carlo. A simulação dos dados de radiação fotossinteticamente ativa e temperatura foram realizadas por intermédio de três casos (i) distribuição triangular assimétrica (ii) distribuição normal truncada a 1,96 desvio padrão da média e (iii) distribuição normal bivariada. Os dados simulados foram avaliados por intermédio do teste de homogeneidade de variância de Bartlett e do teste F, teste t, índice de concordância de Willmott, coeficiente angular da reta, o índice de desempenho de Camargo (C) e aderência à distribuição normal (univariada). O modelo utilizado para calcular a produtividade potencial da cultura de soja foi desenvolvido com base no modelo de De Wit, incluindo contribuições de Van Heenst, Driessen, Konijn, de Vries, dentre outros. O cálculo da produtividade deplecionada foi dependente da evapotranspiração potencial, da cultura e real e coeficiente de sensibilidade a deficiência hídrica. Os dados de precipitação pluvial foram amostrados por intermédio da distribuição normal. Sendo assim, a produção diária de carboidrato foi deplecionada em função do estresse hídrico e número de horas diárias de insolação. A interpolação dos dados, de modo a englobar todo o Estado de São Paulo, foi realizada por intermédio do método da Krigagem. Foi verificado que a maior parte das variáveis segue a distribuição normal de probabilidade. Além disso, as variáveis apresentam variabilidade espacial e temporal e o número de anos necessários (tamanho de amostra) para cada uma delas é bastante variável. A simulação utilizando a distribuição normal bivariada é a mais apropriada por representar melhor as variáveis do clima. E o modelo de estimação das produtividades potencial e deplecionada para a cultura de soja produz resultados coerentes com outros resultados obtidos na literatura. / The availability of resources, as much of financial order and human labor, is scarse. Therefore, it must stimulates the regional planning that minimizes the use of resources. Then, the forecast of harvests through modelling techniques must previously on the basis of be carried through the regional characteristics, thus indicating the routes of the research, as well as the regional planning. Then, the aims of this work are: (i) to characterize the climatic variables through different probability distributions; (ii) to verify the spatial and temporal homogeneity of the climatic variables; (iii) to verify the bivaried normal distribution to simulate parameters used to estimate soybean crop productivity; (iv) to propose a model of estimating the magnitud order of soybean crop potential productivity (it depends on the genotype, air temperature, photosynthetic active radiation; and photoperiod) and the depleted soybean crop productivity (it pedends on the potential productivity, rainfall and soil watter availability) based on daily values of temperature, insolation and rain, for the State of São Paulo. The variable used in this study had been the minimum, maximum and average air temperature, insolation, solar radiation, fotosynthetic active radiation and pluvial precipitation, in daily scale, gotten in 27 stations located in the State of São Paulo and six stations located in neighboring States. First, it was verified tack of seven variables in five probability distributions (normal, log-normal, exponential, gamma and weibull), through of Kolmogorov-Smirnov. The spatial and temporal verified through the analysis of grouping by Ward method and estimating the sample size (number of years) for the variable. The generation of random numbers was carried through the Monte Carlo Method. The simulation of the data of photosyntetic active radiation and temperature had been carried through three cases: (i) nonsymetric triangular distribution (ii) normal distribution truncated at 1.96 shunting line standard of the average and (iii) bivaried normal distribution. The simulated data had been evaluated through the test of homogeneity of variance of Bartlett and the F test, t test, agreement index of Willmott, angular coefficient of the straight line, the index of performance index of Camargo (C) and tack the normal distribution (univarieted). The proposed model to simulate the potential productivity of soybean crop was based on the de Wit concepts, including Van Heenst, Driessen, Konijn, Vries, and others researchers. The computation of the depleted productivity was dependent of the potential, crop and real evapotranspirations and the sensitivity hydric deficiency coefficient. The insolation and pluvial precipitation data had been showed through the normal distribution. Being thus, the daily production of carbohydrate was depleted as function of hydric stress and insolation. The interpolation of the data, in order to consider the whole State of Sao Paulo, was carried through the Kriging method. The results were gotten that most of the variable can follow the normal distribution. Moreover, the variable presents spatial and temporal variability and the number of necessary years (sample size) for each one of them is sufficiently changeable. The simulation using the bivaried normal distribution is most appropriate for better representation of climate variable. The model of estimating potential and depleted soybean crop productivities produces coherent values with the literature results.
35

Independência parcial no problema da satisfazibilidade probabilística / Partial Independence in the Probabilistic Satisfiability Problem

Eduardo Menezes de Morais 20 April 2018 (has links)
O problema da Satisfazibilidade Probabilística, PSAT, apesar da sua flexibilidade, torna exponencialmente complexa a modelagem de variáveis estatisticamente independentes. Esta tese busca desenvolver algoritmos e propostas de relaxamento para permitir o tratamento eficiente de independência parcial pelo PSAT. Apresentamos uma aplicação do PSAT ao problema da etiquetagem morfossintática que serve tanto de motivação como de demonstração dos conceitos apresentados. / The Probabilistic Satisfiability Problem, PSAT, despite its flexibility, makes it exponentially complicated to model statistically independent variables. This thesis develops algorithms and relaxation proposals that allow an efficient treatment of partial independence with PSAT. We also present an application of PSAT on the Part-of-speech tagging problem to serve both as motivation and showcase of the presented concepts.
36

Analyse probabiliste et multi-données de la source de grands séismes / Probabilistic and multi data analysis of large earthquakes source physics

Bletery, Quentin 27 November 2015 (has links)
Les séismes sont le résultat de glissements rapides le long de failles actives chargées en contraintes par le mouvement des plaques tectoniques. Il est aujourd'hui établi, au moins pour les grands séismes, que la distribution de ce glissement rapide le long des failles pendant les séismes est hétérogène. Imager la complexité de ces distributions de glissement constitue un enjeu majeur de la sismologie en raison des implications potentielles dans la compréhension de la genèse des séismes et la possibilité associée de mieux anticiper le risque sismique et les tsunamis. Pour améliorer l'imagerie de ces distributions de glissement co-sismique, trois axes peuvent être suivis: augmenter les contraintes sur les modèles en incluant plus d'observations dans les inversions, améliorer la modélisation physique du problème direct et progresser dans le formalisme de résolution du problème inverse. Dans ce travail de thèse, nous explorons ces trois axes à travers l'étude de deux séismes majeurs: les séisme de Tohoku-Oki (Mw 9.0) et de Sumatra-Andaman (Mw 9.1-9.3) survenus en 2011 et 2004, respectivement. / Earthquakes are the results of rapid slip on active faults loaded in stress by the tectonic plates motion. It is now establish - at least for large earthquakes - that the distribution of this rapid slip along the rupturing faults is heterogeneous. Imaging the complexity of such slip distributions is one the main challenges in seismology because of the potential implications on understanding earthquake genesis and the associated possibility to better anticipate devastating shaking and tsunami. To improve the imaging of such co-seismic slip distributions, three axes may be followed: increase the constraints on the source models by including more observations into the inversions, improve the physical modeling of the forward problem and improve the formalism to solve the inverse problem. In this PhD thesis, we explore these three axes by studying two recent major earthquakes: the Tohoku-Oki (Mw 9.0) and Sumatra-Andaman (Mw 9.1-9.3) earthquakes, which occured in 2011 and 2004 respectively.
37

Strukturelle Ansätze für die Stereorekonstruktion

Shlezinger, Dmytro 18 July 2005 (has links)
Die Dissertation beschäftigt sich mit Labeling Problemen. Dieses Forschungsgebiet bildet einen wichtigen Teil der strukturellen Mustererkennung, in der die Struktur des zu erkennenden Objektes explizit berücksichtigt wird. Die entwickelte Theorie wird auf die Aufgabe der Stereorekonstruktion angewendet. / The thesis studies the class of labeling problems. This theory contributes to the new stream in pattern recognition in which structure is explicitly taken into account. The developed theory is applied to practical problem of stereo reconstruction.
38

Slumpen och Guds försyn : Ett försök att karaktärisera slumpbegreppet / Chance and God's providence : An attempt to characterize chance

Söderlind, Lennart January 2020 (has links)
Why is there a phenomenon of chance in the created world? There are many different probability distributions and does that point at different ideas of chance? Given that God has created the whole universe, why is chance an element of that universe of ours? Does He use chance as a mechanism for His providence? There is a common apprehension of the laws of nature, that they are statistically attained in an asymptotic behaviour over a long period of time. The laws of probability are likewise evolved in the same fashion, as shown in the paper. The universe seems to be lawfully constructed according to both natural laws and probability laws. It is a clear conclusion to regard chance as an intrinsic concept of the world. But, why are there so many ideas of chance despite this common feature of the world? Next section in the paper addresses the many conceptions of chance and works out an idea of how to look at these conditions. The paper results in a presentation of a hierarchy, where different events with their probability distributions might be gathered to some more common properties of chance. The question rises if God is working on that higher level of hierarchy.  This paper has come to a conclusion that, because there are that many ideas of chance and that many probability distributions, we might lack the idea of chance.
39

Applying Data Analytics to Freight Train Delays in Shunting Yards

Minbashi, Niloofar January 2020 (has links)
The European Commission has foreseen a modal share of 30% by 2030 for rail freight transport. To achieve this increase in the modal share, enhanced reliability of rail freight services is required. Optimal functioning of shunting yards is one of the areas that can improve this reliability. Shunting yards are large areas allocated to reassemble freight trains for dispatching to new destinations. Their productivity has a direct impact on the overall performance of a rail freight network. Therefore, analysing and modelling of departure deviations from shunting yards are required to enhance the interactions between shunting yards and the network; this thesis contributes to this gap. Paper I investigates the probability and temporal distribution of departure deviations using a large data set comprising 250,000 departures over seven years from two main shunting yards (Malmö and Hallsberg) in Sweden. The probability distribution of departure deviations is found comparing four main distributions including the exponential, the log-normal, the gamma, and the Weibull according to the maximum likelihood estimates and the results of the Anderson-Darling goodness of fit test.  The log-normal and the gamma are shown the best fits for departure deviations: the former on delays, and the latter on early departures. In the temporal delay distribution, the weekly and monthly, but not yearly delayed departures are positively correlated with the network usage. However, for hourly delayed departures, a shunting yard involved with international traffic does not show any correlation between delayed departures and the network usage, whereas a domestic shunting yard shows a significant negative correlation between these two parameters.  The findings obtained from this thesis contribute to a better understanding of departure deviations from shunting yards, and can be applied in enhancing the operations and capacity utilization of shunting yards in future models. Papers II and III analyse the relationship between congestion in the arrival yard and departure delays using the same data set as paper I.  According to previous research, congestion plays an important role in shunting yard delays. With defining congestion as the number of arriving trains before departure time, paper II analyses this relationship limiting the arrivals and departures between the two shunting yards considering varying time periods before departure,whereas Paper III elaborates the analysis by defining congestion level in a fixed period of time before departure time including all arrivals and departures. Considering the data set used in the analysis, the results show that there is no significant relationship between the congestion in the arrival yard and departure delays of trains. It is possible that congestion may not impact the departure delays of trains, but it may impact the departure delays of wagons due to missed wagon connection or increasing wagon idle time, which can be explored with the availability of wagon connection data.  Additionally, future elaboration of congestion definition, covering congestion at the shunting yard level, may lead to further improved analyses. / Europeiska kommissionen har förutspått en markansandel på 30% framtill 2030 för järnvägstransporter av gods. För att uppnå denna ökning krävsökad tillförlitlighet hos järnvägstransporttjänster. Rangergodsbangårdars optimalafunktion är ett av de områden som kan förbättra denna tillförlitlighet.Rangergodsbangårdar stora områden som är avsedda för att koppla ihopgodståg för sändning till nya destinationer. Deras produktivitet har en direktinverkan på järnvägsnätets totala prestanda. Därför krävs analys och modelleringav avvikelser från dessa noder för att förbättra interaktionen mellanrangergodsbangårdar och järnvägsnätet. I papper I undersöks sannolikheten och den tidsmässiga fördelningen avavvikelser med hjälp av en stor datamängd som omfattar 250 000 avgångaröver sju år från två rangergodsbangårdar (Malmö och Hallsberg) i Sverige.Sannolikhetsdistributioner av avvikelser jämförs med fyra huvuddistributioner,exponentiell, log-normal, gamma och Weibull enligt de maximalasannolikhetsuppskattningarna och resultaten av Anderson-Darling godhetav passningstest. Log-normal och gamma visar sig passa bäst för avvikelser:den förstnämnda vid förseningar och den senare vid tidiga avgångar. I dentidsmässiga fördröjningsfördelningen är de veckovisa och månatliga men inteårliga försenade avgångarna positivt korrelerade med järnvägsnätets nyttjandegrad.För försenade avgångar per timme visar dock en rangergodsbangårdsom är inblandad i internationell trafik ingen korrelation mellan försenadeavgångar och järnvägsnätets nyttjandegrad, medan en inhemsk rangergodsbangårdvisaren signifikant negativ korrelation mellan dessa två parametrar.Resultaten från denna avhandling bidrar till en bättre förståelse av avvikelserfrån rangergodsbangårdar och kan användas för att förbättra drift och kapacitetsutnyttjandeav rangergodsbangårdar växelplatser i framtida modeller. Papper II och III analyserar förhållandet mellan trängsel i ankomstgårdenoch avgångsförseningar med hjälp av samma datamängd som i papperI. Enligt tidigare analyser spelar trängsel en viktig roll vid förseningar förrangergodsbangårdar. Trängsel definieras som antalet ankommande tåg föreavgångstid och papper II analyserar detta förhållande som begränsar ankomsteroch avgångar mellan de två rangergodsbangårdar med beaktande av olikatidsperioder före avgång, medan papper III utvecklar analysen genom attdefiniera trängselnivån under en fast tidsperiod före avgångstid inklusive allaankomster och avgångar. Med tanke på datamängden som användes i analysenvisar resultaten att det inte finns något signifikant samband mellan trängselni ankomstgården och tågens förseningar. Det är möjligt att trängsel kanskeinte påverkar tågens avgångsfördröjningar, men det kan påverka vagnarnasavgångsfördröjningar på grund av missad vagnanslutning eller öka vagnenstomgångstid, vilket kan undersökas med vid tillgång av vagnanslutningsdata.Dessutom kan framtida vidareutveckling av definitionen av trängsel som påen detaljerad nivå täcker rangergodsbangårdars alla delar, leda till ytterligareförbättrade analyser. / <p>QC 20201105</p> / Shift2Rail / FR8HUB
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Statistical and Machine Learning Approaches For Visualizing and Analyzing Large-Scale Simulation Data

Hazarika, Subhashis January 2019 (has links)
No description available.

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