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Medium Mn TRIP steels are amongst the most widely researched third generation advanced high strength steels (3G-AHSSs) as they are ideal candidates for automotive light-weighting applications owing to their superior strength and ductility balance. However, the thermal processing cycles of these steels need to be compatible with the industrial continuous galvanizing line (CGL) in order to successfully employ them in the automotive manufacturing industry. The main objective of the present research was to develop a CGL compatible thermal processing cycle for a prototype medium Mn steel that would produce significant volume fractions of chemically stable retained austenite and exhibit mechanical properties consistent with established 3G-AHSS targets. In that regard, the effects of intercritical annealing (IA) time and temperature and starting microstructure were determined in the first part of this research. The as-received tempered martensite (S-TM) and heat treated martensite (S-M) were the two different starting microstructures studied in this research. In this case, the overaging temperature (OT) treatment (460°C for 20s) was kept constant. It was found that high volume fractions (≥ 0.30) of retained austenite were achieved for S-M samples intercritically annealed at 675°C for shorter times (i.e. 60 to 120s) compared to S-TM samples. TEM analysis of the S-M samples showed that most of the retained austenite was present in a film type morphology, which is known to be more stable chemically and mechanically compared to the block type morphology. The tensile test results showed that although both the S-TM and S-M samples exhibited a high strength/ductility balance, the S-M samples, particularly the S-M 675°C + 120s samples, showed more potential in terms of CGL compatibility and achieving 3G-AHSS target mechanical properties. The effect of OT holding time was determined in the second part of this research. In that regard, the OT holding time was varied form 20s to 120s for selected S-TM and S-M samples. The S-TM 710°C samples with increased OT holding times (60s and 120s) had a significant increase in retained austenite volume fraction compared to the baseline 20s OT samples. However, the retained austenite volume fractions did not change for S-M samples regardless of OT holding time. It was also found that the mechanical properties of the annealed S-TM and S-M steels depended on the OT holding time. For the S-TM samples with > 120s IA holding times, longer OT holding times (60s and 120s) produced chemically unstable retained austenite which transformed rapidly at low strain resulting in low UTS × TE products. However, although longer OT holding times significantly increased the yield strength of the annealed S-M samples, the UTS × TE product decreased significantly owing to decreased retained austenite stability. Finally, based on the results of this research, it was concluded that the prototype medium Mn TRIP steel can achieve 3G-AHSS target mechanical properties using CGL-compatible thermal processing cycles. Moreover, depending on successful reactive wetting, it may be possible to perform both thermal processing and galvanizing of this steel in the industrial CGL. / Thesis / Master of Applied Science (MASc)

The Portfolio Analysis Management Office (PAMO) for the Aeronautics Research Mission Directorate (ARMD) at NASA Headquarters tasked the Systems Analysis and Concepts Directorate at NASA Langley to combine efforts with Virginia Tech to develop a global demand model with the capability to predict future demand in the air transportation field. A previous study (Alsalous, 2015) started the development of the Global Demand Mode (GDM) to predict air travel demand based on Gross Domestic Product (GDP) and population trends for 3,974 airports worldwide. The study was done from year 2016 to year 2040. This research project intends to enhance the GDM capabilities. A Fratar model is implemented for the distribution of the forecast demand during each year. The Fratar model uses a 3,974 by 3,974 origin-destination matrix to distribute the demand among 55,612 unique routes in the network. Moreover, the GDM is capable to estimate the aircraft fleet mix per route and the number of flights per aircraft that are needed to satisfy the forecast demand. The model adopts the aircraft fleet mix from the Official Airline Guide data for the year 2015. Once the aircraft types are distributed and flights are assigned, the GDM runs an aircraft retirement and replacement analysis to remove older generation aircraft from the network and replace them with existing or newer aircraft. The GDM continues to evolve worldwide aircraft fleet by introducing 14 new generation aircraft from Airbus, Boeing, Bombardier, and Embraer and 5 Advanced Technology Aircraft from NASA. / Master of Science / The Portfolio Analysis Management Office (PAMO) for the Aeronautics Research Mission Directorate (ARMD) at NASA Headquarters tasked the Systems Analysis and Concepts Directorate at NASA Langley to combine efforts with Virginia Tech to develop a global demand model with the capability to predict future demand in the air transportation field. A previous study (Alsalous, 2015) started the development of the Global Demand Mode (GDM) to predict air travel demand based on Gross Domestic Product (GDP) and population trends for 3,974 airports worldwide. The study was done from year 2016 to year 2040. The previous study done by Alsaous, predicts how many seats will be departing out of the 3,974 airports worldwide. This project intends to use the outputs of the GDM and distribute the seats predicted among the airports. The objective is to predict how many seats will be offered that will be departing from airport “A” and arriving at airport “B”. For this, a Fratar model was implemented. The second objective of this project is to estimate what will the aircraft fleet be in the future and how many flights will be needed to satisfy the predicted air travel demand. If the number of seats going from airport A to airport B is known, then, by analyzing real data it can be estimated what type of aircraft will be flying from airport “A” to airport “B” and how many flights each aircraft will have to perform in order to satisfy the forecasted demand. Besides of estimating the type of aircraft that will be used in the future, the modeled created is capable of introducing new aircraft that are not part of the network yet. Fourteen new generation aircraft from Airbus, Boeing, Bombardier, and Embraer and 5 Advanced Technology Aircraft from NASA.

<p>Analyses of nuclear reactor safety have increasingly required coupling of full three dimensional neutron kinetics (NK) core models with system transient thermal-hydraulics (TH) codes. To produce results within a reasonable computing time, the coupled codes use different spatial description of the reactor core. The TH code uses few, typically 5 to 20 TH channels, which represent the core. The NK code uses explicit node for each fuel assembly. Therefore, a spatial mapping of coarse grid TH and fine grid NK domain is necessary. However, improper mappings may result in loss of valuable information, thus causing inaccurate prediction of safety parameters.</p><p>The purpose of this thesis is to study the sensitivity of spatial coupling (channel refinement and spatial mapping) and develop recommendations for NK-TH mapping in simulation of safety transients – Control Rod Drop, Turbine Trip, Feedwater Transient combined with stability performance (minimum pump speed of recirculation pumps).</p><p>The research methodology consists of spatial coupling convergence study, as increasing number of TH channels and different mapping approach the reference case. The reference case consists of one TH channel per one fuel assembly. The comparison of results has been done under steady-state and transient conditions. Obtained results and conclusions are presented in this licentiate thesis.</p>

Generalised linear models (GLMs) provide a flexible and sound basis for calibrating gravity models for trip distribution, for a wide range of deterrence functions (from steps to splines), with K factors and geographic segmentation. The Tanner function fitted Wellington Transport Strategy Model data as well as more complex functions and was insensitive to the formulation of intrazonal and external costs. Weighting from variable expansion factors and interpretation of the deviance under sparsity are addressed. An observed trip matrix is disaggregated and fitted at the household, person and trip levels with consistent results. Hierarchical GLMs (HGLMs) are formulated to fit mixed logit models, but were unable to reproduce the coefficients of simple nested logit models. Geospatial analysis by HGLM showed no evidence of spatial error patterns, either as random K factors or as correlations between them. Equivalence with hierarchical mode choice, duality with trip distribution, regularisation, lorelograms, and the modifiable areal unit problem are considered. Trip distribution is calibrated from aggregate data by the MVESTM matrix estimation package, incorporating period and direction factors in the intercepts. Counts across four screenlines showed a significance similar to a thousand-household travel survey. Calibration was possible only in conjuction with trip end data. Criteria for validation against screenline counts were met, but only if allowance was made for error in the trip end data.

This diploma thesis is focusing on use of Botanical garden of Faculty of Science, Charles University in Prague by teachers as a destination for class field trips. Teachers use this garden with different objectives and different intensity. This diploma thesis provides a summary of this using by the processing of the survey, which took place in elementary school teachers and high school teachers. This work is testing the following hypotheses: 1. Teachers with length of practice above twenty years use the field trip less than teachers with length of practice under twenty years. 2. Men use guided tours more than women. 3. High school teachers use geopark for tour more than elementary school teachers. 4. Teachers with length of practice above twenty years visit gardens other than Faculty of Science, Charles University in Prague and the Botanical Garden in Prague Troja less than teachers with length of practice under twenty years. The thesis summarizes basic information about the field trip as an organizational form. The thesis also deals with the Botanical Garden of faculty of science Charles University in Prague, its collections, history, and possibilities of using in schools.

Este estudo teve como objetivo o desenvolvimento de procedimentos para estimar distâncias de viagens intrazonais com base em dados de pesquisas origem-destino (O/D). A análise conduzida na aplicação apresentada foi baseada em dados de uma pesquisa O/D realizada na cidade de São Carlos, Brasil. A área urbana foi subdividida várias vezes para produzir 471 zonas de análise de tráfego (TAZ) para análise. A análise partiu da identificação de características geométricas das zonas de análise de tráfego (TAZ) que podem influenciar as distâncias das viagens intrazonais. Em seguida, indicadores numéricos dos padrões geométricos selecionados foram comparados com os valores médios das distâncias intrazonais, a fim de procurar por evidências de correlação entre estas variáveis. Duas abordagens analíticas foram exploradas: i) contínua e ii) descontínua. No primeiro caso, todas as viagens foram consideradas em um único conjunto de dados, enquanto que no segundo caso, o conjunto de dados foi dividido em dois subgrupos com características homogêneas. Os conjuntos de dados com maior correlação foram usados para construir modelos globais e estratificados para estimar distâncias intrazonais. Nos modelos globais, viagens a pé, de bicicleta e de automóvel foram analisadas como uma única base de dados. Nos modelos estratificados, os três modos de transporte foram considerados separadamente. Foram ajustados, também, modelos adicionais que permitam estimar as viagens por um modo de transporte específico a partir de valores globais de distâncias intrazonais. Os valores obtidos com estes modelos foram então comparados com as estimativas de outros modelos encontrados na literatura. Os modelos descontínuos aqui obtidos superaram claramente os modelos tradicionais. Isto sugere que podem constituir alternativas para substituir os modelos tradicionais para estimar distâncias médias de viagens intrazonais, pelo menos no caso das cidades médias brasileiras. / This study aimed at the development of procedures for estimating intrazonal trip distances based on data of origin-destination (O/D) surveys. The analysis conducted in the application presented was based on an O/D survey conducted in the city of São Carlos, Brazil. The urban area was subdivided several times to produce 471 traffic analysis zones (TAZ) for analysis. Geometrical characteristics of the zones that can influence the distances of intrazonal trips were then identified. Next, numerical indicators of the selected geometrical patterns were compared with the average values of intrazonal trip distances in order to look for evidences of correlation between these variables. Two analytical approaches were explored: i) continuous and ii) discontinuous. In the first case, all trips were consideredas a single dataset, whereas in the second case the dataset was split in two subsets with homogeneous characteristics. The datasets with higher correlation were used to build global and stratified models for estimating intrazonal trip distances. In the global models, walking, cycling, and auto trips were all considered as part of a common dataset. In the stratified models, the three transport modes were separately taken into account. Additional models, which were meant to estimate trips per mode based on global values of intrazonal trip distances, were also developed. The values obtained with these models were then compared with the estimations of other models found in the literature. The discontinuous models calibrated in this study clearly outperformed the traditional models. This may be an indication that they can be used to replace the traditional models for estimating average intrazonal trip distances, at least in the case of Brazilian medium-sized cities.

A aplicação do novo conceito de tratamento térmico, chamado de têmpera e partição (Q&P), desenvolvido para a obtenção de aços da terceira geração da classe AHSS (Advanced high strengh steel ou aços avançados de alta resistência), mostra-se uma alternativa para o processamento de ferros fundidos nodulares com alta resistência mecânica. No processo Q&P, o carbono presente na martensita supersaturada, formada na etapa de têmpera, é utilizado para estabilizar a austenita não transformada durante a etapa de partição, mantendo-a estável na temperatura ambiente. Essa rota de tratamento térmico consiste em realizar uma têmpera no material (após uma etapa prévia de austenitização) numa faixa de temperatura entre o Ms e Mf (temperatura de início e fim da transformação martensítica, respectivamente), seguido de um reaquecimento e manutenção a uma temperatura acima do Ms (etapa isotérmica de partição) com o objetivo de que o carbono migre da martensita supersaturada para a austenita remanescente promovendo sua estabilização. Essa partição do carbono só é possível caso a precipitação da cementita seja suprimida, e isso é conseguido com a presença de elementos de liga, como o Si e/ou Al. Neste trabalho foi feito um estudo sobre as características microestruturais e mecânicas de um ferro fundido nodular (3,47%C; 2,47%Si; 0,2%Mn) submetido ao tratamento térmico de têmpera e partição, o qual foi denominado neste trabalho como, Q&PDI (Quenched and Partitioned Ductile Iron ou Ferro Fundido Nodular Temperado e Particionado). Para isso foi realizada uma austenitização plena nas amostras, a 880°C, por duas horas, seguida de uma têmpera em óleo pré-aquecido nas temperaturas de 140 e 170°C. A etapa de partição foi feita nas temperaturas de 300, 375 e 450°C, com intervalos de tempo variando de 5 a 120 minutos. A caracterização microestrutural foi realizada através de microscopia ótica, microscopia eletrônica de varredura e EBSD. A técnica de difração de raios-X foi empregada para quantificar a fração volumétrica e o teor de carbono na austenita retida. Ensaios de dilatometria, difração de raios-X \"in situ\" e nanoindentação foram empregados para auxiliar na análise das transformações de fases que ocorreram na etapa de partição, como a transformação bainítica e a precipitação de carbonetos de transição nas placas de martensita. A caracterização mecânica foi feita através de ensaios de tração, impacto, dureza, nanoindentação, tenacidade à fratura e resistência à fadiga. Ensaios de compressão auxiliaram na análise da transformação martensítica induzida por deformação. Os resultados obtidos mostraram que é possível obter ferros fundidos nodulares com alta resistência mecânica (limite de resistência >1450 MPa), com consideráveis ductilidade (de até 9%) e energia absorvida sob impacto (de até 81 J), bem como tenacidades à fratura de 55 MPa.m1/2 e limites de fadiga de 550 MPa. Este comportamento é proporcionado por uma microestrutura singular, constituída por uma dispersão homogênea de placas de martensita numa matriz de ausferrita bastante refinada, com consideráveis frações volumétricas de austenita retida (max. 23%). / Quenching and partitioning (Q & P), a new heat treatment concept developed to obtain third generation AHSS (Advanced High Strength Steel), is an alternative for processing of nodular cast irons in order to obtain high mechanical strength. In the Q & P process, the carbon present in the supersaturated martensite formed in the quenching step diffuses towards the untransformed austenite during the partition step, keeping it stable at room temperature. This heat treatment route consists of quenching the material (after a previous step of austenitization) in a temperature range between Ms and Mf (beginning and end temperature of the martensitic transformation, respectively), followed by reheating and maintenance at a temperature above the Ms (isothermal stage of partition) allowing the carbon to migrate from the supersaturated martensite to the remaining austenite, promoting its stabilization. This partition of carbon is only possible if precipitation of cementite is suppressed; this is achieved adding alloying elements such as Si and/or Al. In this work a study was made on the microstructural and mechanical characteristics of a ductile iron (3.47%C; 2.47%Si; 0.2%Mn), submitted to a Q&P heat treatment, in this work named Q & PDI (Quenched and Partitioned Ductile Iron). A full sample austenitization was carried out at 880 ° C for two hours, followed by a pre-heated oil quanching at temperatures of 140 and 170 ° C. The partitioning step was at temperatures of 300, 375 and 450Â ° C, with time intervals ranging from 5 to 120 minutes. Microstructural characterization was performed through optical microscopy, scanning electron microscopy and EBSD. The X-ray diffraction technique was used to quantify the volumetric fraction and the carbon content in the retained austenite. Dilatometry, X-ray diffraction \"in situ\" and nanoindentation were also used to aid in the analysis of the phase transformations that occurred in the partitioning stage, such as the bainitic transformation and the precipitation of transition carbides in the martensite plates. Mechanical characterization was performed through tensile, impact, hardness, nanoindentation, fracture toughness and fatigue strength tests. Compression tests aided in the analysis of the deformation induced martensitic transformation. The results showed that it is possible to obtain nodular cast irons with high mechanical strength (resistance limit> 1450 MPa), with considerable ductility (up to 9%) and energy absorbed under impact (up to 81 J), as well as fracture toughness of 55 MPa.m -1 / 2 and fatigue limits of 550 Mpa. This behavior is provided by a unique microstructure, consisting of a homogeneous dispersion of martensite plates in a very refined ausferrite matrix, with considerable volumetric fractions of retained austenite (max. 23%).

Le problème de routage de véhicules avec fenêtres de temps et routes multiples (MTVRPTW) est une généralisation du problème de routage de véhicules avec fenêtres de temps (VRPTW). Dans le MTVRPTW, on autorise un véhicule à effectuer plusieurs routes durant une période de planification, ce qui permet d'optimiser les transports lorsque le nombre de véhicules est limité et peu élevé. Nous proposons dans cette thèse la première méthode exacte permettant de résoudre ce problème. Notre modélisation prend la forme d'un problème de couverture des clients dont les variables sont des routes. Des contraintes d'exclusion mutuelle expriment la disponibilité des véhicules. Nous utilisons la Génération de Colonnes, avec un sous-problème effectuant, par programmation dynamique, une recherche de plus court chemin élémentaire contraint en ressources. Notre méthode de programmation dynamique tient compte des dépendances de plusieurs ressources grâce à la notion de label représentatif, et est ainsi plus efficace qu'une approche classique. La méthode de Génération de Colonnes est incluse dans un schéma de Branch and Price composé de deux types de branchement, l'un basé sur les arcs, l'autre sur la résolution d'un VRPTW. Nous avons mis en place diverses méthodes accélératrices spécifiques du MTVRPTW. Nous donnons les résultats de l'algorithme sur les instances de Solomon. Des résultats issus de méthodes exactes étaient disponibles dans la littérature pour le MTVRPTW avec durée limite sur les routes. Nous avons proposé un nouvel algorithme plus performant, et basé sur nos méthodes, pour cette variante du problème. / The multi-trip vehicle routing problem with time windows (MTVRPTW) is a generalization of the vehicle routing problem with time windows (VRPTW). In the MTVRPTW, one vehicle can perform several trips during a planning period. This allows optimizing the transport when the number of vehicles is limited and small.We propose here the first exact method for solving this problem.Our model is designed as a coverage problem for customers where the variables are trips. Mutual exclusion constraints express the availability of vehicles. We use a column generation scheme in which the sub-problem is an elementary shortest path problem with resource constraints (ESPPRC). Our dynamic programming method for ESPPRC takes into account dependencies of several resources through the concept of representative label. It is thus more efficient than a conventional approach. The column generation method is included in a Branch and Price scheme with two types of branching. One is based on arc selection, and the other on solving a VRPTW. We have implemented various accelerating methods which are specific to MTVRPTW. We give the results of our algorithm on Solomon instances.Results from exact methods were available in the literature for the MTVRPTW with time limit on the trips. We proposed a new and more efficient algorithm, based on our methods, to solve this variant of the problem.