Dissertations / Theses on the topic 'Simualtion'

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1

Shiferaw, Mamo Abel. "Regression with a Partially Censored Dependent Variable Under Simualtion Study." Thesis, Örebro universitet, Handelshögskolan vid Örebro Universitet, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-37532.

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2

Ni, Wuyen Wayne. "A simualtion [sic] study of left turning movement at an unsignalized intersection /." This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-12232009-020056/.

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Barbosa, Saldana Juan Gabriel. "Numerical simualtion of mixed convection over a three-dimensional horizontal backward-facing step." Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/2353.

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A FORTRAN code was developed to numerically simulate the mixed convective flow over a three-dimensional horizontal backward-facing step. The momentum and energy equations under the assumption of the Boussinesq approximation were discretized by means of a finite volume technique. The SIMPLE algorithm scheme was applied to link the pressure and velocity fields inside the domain while an OpenMP parallel implementation was proposed to improve the numerical performance and to accelerate the numerical solution. The heating process corresponds to a channel heated from below at constant temperature keeping insulated all the other channel walls. In addition, the back-step was considered as a thermally conducting block and its influence in the heating process was explored by holding different solid to fluid thermal conductivity ratios. The effects over the velocity and temperature distribution of buoyancy forces, acting perpendicular to the mainstream flow, are studied for three different Richardson numbers Ri=3, 2, and 1 and the results are compared against those of pure forced convection Ri=0. In these simulations the Reynolds number is fixed at 200 while the bottom wall temperature is adjusted to fulfill the conditions for the different Ri. Under this assumption, as Ri increases the buoyancy effects are the dominant effects in the mixed convective process. The numerical results indicate that the velocity field and the temperature distribution for pure forced convection are highly distorted if compared with the mixed convective flow. If the Ri parameter is increased, then the primary re-circulation zone is reduced. Similarly, as the buoyancy forces become predominant in the flow, the convective rolls, in the form of spiral-flow structures, become curlier and then higher velocity components are found inside the domain. The temperature field distribution showed that as the Ri is increased a thicker layer of high temperature flow is located at the channel??s top wall as a result of the higher rates of low-density flow moving to the top wall. The flow is ascending by the channel sidewalls, while descending by the channel span-wise central plane. The parallel numerical strategy is presented and some results for the performance of the OpenMP implementation are included. In this sense, linear speedup was obtained when using 16 possessors in parallel.
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Kim, Seongchan. "An analysis of International Energy Conservation Code (IECC)-compliant single-family residential energy use." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1728.

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Qin, Xiaohao, and Jiahao Cheng. "Dynamic simulation of a planetary gear for robots." Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-85627.

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Gear drives are widely applied in mechanical transmission systems and very accurate transmission systems are needed. In the robot industry, the planetary gear train (PGT) is commonly used to promote the torque transmission. One of the advantages of an ideal PGT is that the incoming torque is divided equally among the planet gear wheels. However, different manufacturing and assembling deviations may cause uneven load distributions. This is a serious problem that affects the load capacity and the stability of the torque transmission.SwePart has designed and patented a planetary gear blazing for very high-accuracy robots and zero gaps in the gear maintained during its operating time [25]. The purpose of this project is to determine how deviations such as pitch deviation and stiffness affect the magnitude of the contact forces acting on gear teeth from the ideal geometry.In order to model the ideal geometry, an inspection of the SwePart’s gears was needed. By using SOLIDWORKS, the common normal line which is perpendicular to the teeth profiles can be defined. This means that the base circle which is tangential to that common normal line can also be found.The gear profiles of the PGTs in this study were created using the software MATLAB based on the parametric equation of involute of the base circle. The data generated by MATLAB were then used to create 3D models of the PGTs in SOLIDWORKS. The gears were split into 2N+1 parts if the number of teeth is N, since different magnitude of the pitch deviations needs to be studied. It is more informative to compare the magnitude of contact forces acting on each half tooth.When the gears which are similar to the SwePart’s gears were finished, the x_t document was exported from SOLIDWORKS and imported into MSC_ADAMS to make the simulations. After that the materials were defined in the model and contact forces were added between teeth of the planetary gear and the ring gear. The magnitude of the contact forces acting on the rigid and flexible gear teeth were then compared. So, MSC_ADAMS needs to be used to mesh the rigid bodies to the flexible ones automatically by calling MSC_Nastran.MATLAB was used to compare the results and graphs from different ADAMS models.
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Schafrik, Steven Joseph. "A New Style of Simulation Model for Mining Systems." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/35285.

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The algorithms for the mathematical modeling to predict productivity of underground room-and-pillar mining systems are well-known and documented. These algorithms consider the time-varying relationships between mining equipment for a given geometry of operations as well as other constraints. This study presents a newly developed, user-friendly visual simulation computer tool for the Windows environment. This tool can be easily customized and utilized by field engineers and will help mine operators plan the optimum mining sequence for different mine geometries and equipment layouts. Program output includes monitoring of shift data, equipment utilization indices, and so forth. The simulation technique can be used with any environment. Use of the system is demonstrated in different mining equipment configurations. Development and validation of the system was aided by the Peabody Group.
Master of Science
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Schwede, Dirk Alexander. "Towards a Universal and Integrated Digital Representation of Physical Processes." Thesis, The University of Sydney, 2006. http://hdl.handle.net/2123/1433.

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This thesis describes the exploration and the development of computational means to investigate the behaviour of design objects before they are available for investigation in the physical world. The motivation is to inform the design process about the design object’s performance in order to achieve better – more performance-oriented – design outcomes in the sense of energy efficiency and comfort performance than can be achieved by conventional design techniques. The research is structured into five successive parts. - Concept Development – A review of the objective domains comfort assessment and energy efficiency assessment is conducted and the design process, human design activity and the application of simulation in the architectural domain is discussed in order to identify requirements for the development of computational means for design analysis. Requirements regarding model content, model features and model integration are developed. The main requirements are that a highly integrated, three-dimensional and dynamic representation of physical processes is needed and that a universal and integrated representation is required. - Concept Formulation – Based on the identified requirements, the concept for a model is formulated. In order to achieve a universal and integrated representation of physical processes the concept uses the approach of a constructive language. Space is represented with autonomous spatial elements, called congeneric cells. Interaction between the cells is represented by near- and remote-conjunctions. Physical and geometric self-contained formulations of the model reduce the model input requirements, so that geometric information and simple property specification (material, activity) is sufficient to describe the design object in the model. - Model Development – The concept is formulated in mathematical physical terms based on well known physical laws and building physical models (first-principle approach). Heat and moisture conduction, diffusion of various components and a flow model is formulated as near-conjunction processes. Heat radiation, light and sound are modelled with a radiosity approach as remote-conjunctions. The simulation algorithm, which governs the interaction between the cells in order to represent the behaviour of space, is explained. - Computational Implementation – The concept and the model is tested by implementation of a prototype using C++ and OpenGL on a conventional Pentium 4 notebook. The prototype consists of three parts: user-interface, model translator and simulation engine. The user interface functions as model-input and result-output device. The implementation of the concept and of further model parts is described in detail. - Assessment and Testing – The developed concept and the model, as implemented in the prototype, are tested and assessed against the initially developed requirements. The physical model is assessed in regard to plausibility and accuracy of the representation of the physical phenomena. At the end of the thesis the project is summarized, the achievements of the project’s objectives are discussed critically and issues for future research are suggested. Possible applications of the developed model are listed, and the contributions to the application of computational simulation in the architectural domain, developed in this research, are named. At the current stage the required processing time and high memory requirements prevent implementation of a design assessment system, following the suggested concept, at a useful scale. Also the developed physical models require further refinement and testing. Although the general feasibility of the concept and the model was successfully demonstrated, its implementation in a fully applicable design assessment system based on the universal and integrated representation of physical processes was not achieved at this stage. While detailed description and analysis is given in the body of the thesis, detailed formulations of the work and the developed model are given in the appendix. The body and the appendix together provide a complete picture of the research presented.
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Aoun, Laurene. "Mechanical properties of growing microtumors : engineering microdevices for the mechanical investigation of tumor spheroids models." Toulouse 3, 2014. http://www.theses.fr/2014TOU30137.

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Le développement tumoral est influencé par des signaux biochimiques mais également biomécaniques. Plusieurs études ont montré que la modification de l'environnement mécanique peut moduler la croissance tumorale des cellules, la migration, l'invasion ainsi que la prolifération et l'apoptose. Cependant, les propriétés mécaniques intrinsèques des tumeurs sont elles peu connues. Le sphéroïde est un modèle multicellulaire reproduisant l'organisation des cellules dans une tumeur par les interactions cellule-cellule et cellule-microenvironnement. Afin d'étudier les propriétés mécaniques des sphéroïdes, mon projet était de déterminer les forces exercées par des sphéroïdes tumoraux en cours de croissance. Dans cet objectif, j'ai développé des micropilliers en PDMS, de rapport de forme élevé et démontré qu'ils se comportent comme des capteurs de force. Nous avons mesuré les forces générées par des sphéroïdes de cancer mammaire et nous avons constaté que la croissance des sphéroïdes induit un déplacement croissant des piliers avec le temps et que les forces correspondantes sont de l'ordre de quelques centaines de nanoNewtons. Nous avons trouvé que les forces générées dépendent de la rigidité de l'obstacle environnant, ce qui s'est traduit par la génération des forces plus grandes envers des micropiliers plus rigides. L'ensemble de ces résultats montre que les sphéroïdes en croissance sont capables de détecter leur micro-environnement et générer des forces en fonction de la résistance du dispositif. L'utilisation de ces microdispositifs comme des microcapteurs de force ouvre de nouvelles perspectives dans les domaines de la mécanique des tissus et en pharmacologie anti-tumorale
Tumor growth and progression is influenced not only by biochemical cues but also biomechanical ones. Several studies have shown that the modification of the mechanical environment can modulate tumour cell growth, migration and invasion as well as proliferation and apoptosis. However, little is known about the intrinsic tumour mechanical properties. Spheroids provide a unique 3 dimensional model to study the mechanical properties of tumors since they reproduce the organization of a microtumour in cell-cell and cell-microenvironment interactions. In order to investigate the mechanical properties of spheroids, my project was to determine the forces exerted by tumor spheroids during growth. This was done by engineering biocompatible high aspect ratio PDMS microdevices, using microfabrication technics. We showed that these micropillars serve as force sensors. We have measured the forces generated by mammary cancer cells spheroids and we demonstrated that spheroids under growth induce increasing pillars displacement with time and that the corresponding forces are of the order of a few hundred nanoNewtons. We found as well that the generated forces depend on the rigidity of the surrounding obstacle, which was reflected by the generation of increased forces towards more rigid micropillars. The ensemble of these results shows that growing spheroids are able to sense their microenvironment and generate forces according to the resistance of the device. The use of these microdevices arrays as force microsensors opens new prospects in the fields of tissue mechanics and pharmacological drug screening
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Sassine, Emilio. "Analyse typologique et thermique des maisons anciennes de Lille : Etude expérimentale et numérique des parois verticales." Thesis, Artois, 2013. http://www.theses.fr/2013ARTO0213/document.

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Le secteur des logements présente un potentiel non négligeable d'économies d'énergie surtout au niveau du chauffage qui constitue une part importante des factures énergétiques en France. Notre travail s'inscrit dans l'optique de réduction des consommations énergétiques des logements en étudiant le transfert thermique dans les parois opaques du bâti ancien et en étudiant différentes configurations et différents types d'isolants thermiques. Après une analyse du contexte et des enjeux de la problématique énergétique des bâtiments anciens, nous avons abordé une analyse typologique des maisons anciennes lilloises en identifiant les quatre familles principales de typologies : la maison de courée, la maison ouvrière, la maison de ville et la maison bourgeoise ; en identifiant ainsi leurs ressemblances et leur variantes. Ensuite, nous avons étudié en détails le transfert thermique dans un mur en brique caractéristique de la région Nord-Pas-de-Calais; une étude expérimentale a été comparée à diverses approches théoriques en divers régimes (régime permanent, régime harmonique et régime quelconque). Après l'étude du mur dans son état initial (avant isolation), nous avons caractérisé expérimentalement cinq matériaux isolants (polystyrène, laine de bois, laine de mouton, lin et métisse) pour étudier ensuite leur apport en termes de réduction de déperditions thermiques pour le mur étudié. Nous avons appliqué expérimentalement 3 cm de polystyrène pour l'isolation du mur afin de valider la méthode théorique. Une fois cette dernière validée, une comparaison de différents matériaux isolants et différentes configurations (isolation par l'intérieur et isolation par l'extérieur) a été établie afin d'identifier la configuration et le(s) matériau(x) le(s) plus intéressant(s). Enfin, des simulations thermiques dynamiques à l'échelle du bâtiment ont été réalisées pour les différentes typologies dans le but de valider les résultats obtenus à l'échelle du mur, de comparer les performances énergétiques des différentes typologies et de quantifier les économies d'énergie possibles pour différents bouquets de travaux d'isolation
The housing sector has a significant energy saving potential especially in terms of heating which constitutes an important part of energy bills in France. Our work joins the optics of reducing energy consumption of housing by studying heat transfer in the opaque walls of old buildings and studying different configurations and types of thermal insulation materials. After an analysis of the context and the energy’s problematic of old buildings, we discussed a typological analysis of Lille’s old houses by identifying four main families of typologies: the “courée” house, the worker’s house, the town house and the mansion, thereby identifying their similarities and variations. Then, we thoroughly studied the heat transfer in a brick wall characteristic of the Nord-Pas-de-Calais region; an experimental study was compared to various theoretical approaches in various regimes (steady state, harmonic, and random regime). After the study of the wall in its initial state (before insulation), we experimentally characterized five insulating materials (polystyrene, wood wool, sheep wool, linen and recycled textile) in order to study then their contribution in terms of heat losses’ reduction through the studied wall. We experimentally applied 3 cm of polystyrene wall insulation to validate the theoretical method. Once it was validated, a comparison of different insulating materials and configurations (interior insulation and external insulation) was established to identify the most interesting configuration and insulation material(s). Finally, dynamic thermal simulations on the building scale were carried out for the different buildings typologies in order to validate the results obtained on the wall scale, to compare the energy performance of the different building typologies, and quantify the energy savings potential for thermal insulation scenarios
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Hirtzel, Joanne. "Exploration prospective des mobilités résidentielles dans une agglomération urbaine au moyen d'un modèle de simulation multi-agents (MOBISIM)." Thesis, Besançon, 2015. http://www.theses.fr/2015BESA1005/document.

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Proposer une offre en logements adaptée aux différents besoins et préférences des ménages représente un enjeu important pour les acteurs publics de l’aménagement. Ces besoins et préférences dépendent des caractéristiques des ménages et des changements qu’ils peuvent connaître dans leur cycle de vie (mise en couple, naissance, séparation…). Les facteurs participant aux choix résidentiels sont nombreux (attributs du logement, caractéristiques de l’environnement résidentiel) et interviennent différemment selon les types de ménages. Les dynamiques résidentielles impliquent ainsi une grande variété d’éléments, en interaction les uns avec les autres, et les relations de cause à effet sont difficiles à identifier. Par conséquent, il n’est pas possible de prévoir le comportement résidentiel des ménages pas plus que leurs évolutions possibles sans outil adapté.Pour étudier les dynamiques résidentielles intra-urbaines, nous utilisons dans cette thèse un modèle de simulation des mobilités résidentielles (Mobisim-MR) intégré dans une plateforme de simulation LUTI individu-centrée : Mobisim. Mobisim-MR permet de déterminer, pour chaque année de simulation, les ménages qui déménagent et leur nouvelle localisation résidentielle. En amont de Mobisim-MR, un modèle de simulation des évolutions démographiques (Mobisim-Démo) a été créé au sein de la plateforme Mobisim. Il permet de reproduire de manière dynamique et individu-centrée l’évolution des ménages dans leur cycle de vie. Une partie de la thèse est dédiée au paramétrage ces deux modèles, étape préalable nécessaire à la simulation de scénarios. Un autre volet de la thèse concerne l’exploration du comportement du modèle Mobisim-MR pour évaluer la stabilité des résultats de simulation et leur cohérence (analyse de sensibilité). L’utilisation de modèles individu-centrés est relativement récente en géographie, d’où l’absence de protocole standard pour l’exploration de tels modèles. Un protocole spécifique a été conçu pour explorer le comportement de Mobisim-MR. Ce protocole tient compte de la nature des paramètres du modèle, des contraintes techniques de simulation et de l’objectif pour lequel le modèle a été conçu.Le dernier volet de la thèse consiste en des analyses thématiques visant à étudier l’impact de deux scénarios de politiques de construction de logements sur l’agglomération du Grand Besançon. Ces analyses montrent la capacité de Mobisim-MR à répondre à des questions concrètes d’aménagement et à apporter des éléments de discussion aux acteurs publics en charge des politiques de logement
To ensure that housing supply is suitable to households’ needs and preferences represents a major planning concern. These needs and preferences depend on the households’ characteristics and on their lifecycle changes (union, birth, divorce…). Residential choice factors are numerous (housing and residential environment characteristics) and their role is often different according to the types of households. Residential dynamics involve a great variety of elements, in interaction with each other, and the causal relationships are difficult to identify. Thus, it is not possible to predict the households’ residential behaviour, nor their possible evolutions, without a suitable tool. To study intra-urban residential dynamics, we use a residential mobility simulation model (Mobisim-MR), integrated in an agent-based LUTI simulation platform: Mobisim. For each simulated year, Mobisim-MR allows for determination of households which move and their new residential location. Prior to Mobisim-MR, we created a demographic microsimulation model (Mobisim-Démo) within the Mobisim platform. It allows reproducing households lifecycle evolutions in a dynamic and agent-based way. A part of the thesis is dedicated to the calibration of both models, a required stage preliminary to scenarios simulation. Another part of the thesis concerns the exploration of Mobisim-MR model behaviour, in order to assess the simulation results’ stability and their consistency (sensitivity analysis). Agent-based models use is quite recent in geography, explaining the lack of standard protocol to explore such models. A specific protocol has been designed to explore the behaviour of Mobisim-MR. This protocol takes into consideration the parameters characteristics, simulation technical constraints, and the initial design for which the model has been built.The last part of the thesis consists of thematic analyses aimed at studying the impact of two housing construction planning scenarios in the urban region of Besançon (named le Grand Besançon). These analyses highlight the ability of Mobisim-MR to answer concrete planning questions and to initiate discussion among urban planners
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Penneçot, Christelle. "La simulation en éducation thérapeutique des patients : Recommandations des conditions d’utilisation et compétences visées." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCI002/document.

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Résumé :Introduction: Les recherches sur l’Education Thérapeutique du Patient (ETP) montrent qu’elle peut encore gagner à développer l’ensemble des compétences des patients en utilisant des méthodes pédagogiques interactives. La simulation est rarement utilisée pour aider les personnes atteintes de maladies chroniques à développer ces compétences. L’objectif du travail de thèse était de promouvoir l'utilisation de la simulation dans l'éducation thérapeutique des patients (S-ETP) par : i) la réalisation d’une conférence de consensus sur le sujet et ii) la réalisation d’une étude pilote de la S-ETP.Méthode: Un consensus d'experts a été obtenu avec la participation des patients et des proches aidants experts; des professionnels de la santé spécialisés experts en (ETP) et des experts en simulation. Chaque recommandation a été soumise à un examen exhaustif de la littérature. La qualité des éléments de preuve et la solidité des recommandations ont été évaluées au moyen de critères d'évaluation [GRADE]. L’étude pilote est réalisée sur un échantillon de 24 patients diabètiques dans le but de tester sa faisabilité.Résultats: A la fin du consensus, les experts ont identifié 26 recommandations spécifiques à l'utilisation de la S-ETP. Ils ont proposé des exemples de compétences dans différentes maladies et ont insisté sur l'importance d'adapter les conditions d'utilisation (emplacement, équipement, temps des soins) aux circonstances de l'apprenant et des compétences du patient à développer. Les experts doivent faire preuve d'une grande prudence car cette technique présente des conditions éthiques. L’essai de faisabilité a permis d’étudier la faisabilité de la S-ETP auprés des patients et des soignants.Conclusion: Ces recommandations soulignent le fait que la simulation pourrait apporter une valeur ajoutée en ETP. Elles fournissent le premier cadre pour l'utilisation de la simulation en ETP. La recherche sur la faisabilité et l'acceptabilité de l’utilisation de cette méthode auprès des patients, s’est basé sur le consensus d’expert. Cette étape était nécessaire avant d’évaluer l’efficience et d’établir une taxonomie de la S-ETP
Abstract :Abstract :Introduction: Research in TPE shows that it can still benefit from developing the full range of patient skills through the use of interactive teaching methods. Simulation is rarely used to help individuals with chronic diseases to develop these skills. The objective of the thesis work was to promote the use of simulation in patient therapeutic education by: (i) conducting a consensus conference on the subject and (ii) conducting a pilot study of S-ETP.(S-TPE).Methods: Expert consensus was achieved with the participation of expert patients and caregivers; health professionals specialized in TPE; and simulation experts. Each recommendation was subject to an extensive literature review. The quality of the evidence and the strength of the recommendations were assessed through the evaluation, development and evaluation criteria categories [GRADE criteria].The pilot study is being conducted on a sample of 24 diabetic patients in order to test its feasibility.Results: At the end of the consensus, the experts identified 26 recommendations specific to the use of S-TPE. They proposed examples of skills in different diseases and stressed the importance of adapting the conditions of use (location, equipment, time of the care) to the circumstances of the patient learner and skills to be developed. Experts should exercise great caution as this technique presents ethical requirements.Conclusion: These recommendations underline the fact that simulation could bring added value to TPE. They provide the first framework of the use of simulation in TPE. Research on the feasibility and acceptability of using this method with patients was based on expert consensus. This step was necessary before assessing efficiency and establishing a taxonomy of the S-TPE
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Silva, Mario Luiz Nunes da. "Otimização do processo de laminação transversal com cunha para a produção de eixos com aço SAE 1045." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264466.

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Orientador: Sergio Tonini Button
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-11T13:27:48Z (GMT). No. of bitstreams: 1 Silva_MarioLuizNunesda_D.pdf: 5214131 bytes, checksum: d3b65bf8a08ad05e43b1a4cb009f56b7 (MD5) Previous issue date: 2008
Resumo: O processo Laminação Transversal com Cunha (conhecido em inglês como cross wedge rolling ou CWR) consiste na conformação plástica de produtos por meio de ferramentas em forma de cunhas fixadas em placas planas, côncavas ou convexas ou ainda em rolos de equipamentos de laminação. Apesar das vantagens desse processo associadas à elevada produtividade e minimização das perdas de matéria-prima, o surgimento do defeito interno denominado Mannesmann exige uma inspeção cuidadosa das peças produzidas. Esse defeito tem sua origem no centro das peças laminadas e suas causas ainda não estão totalmente identificadas. Baseando-se no método de elementos finitos, simulações numéricas em três dimensões do processo CWR foram estudadas utilizando-se o programa de simulação MSC Superform para analisar-se a influência das variáveis geométricas (ângulos de conformação e de estiramento e redução relativa) e de processo (temperatura de pré-aquecimento e velocidade de laminação) no aparecimento desse que é considerado o principal defeito do processo. Ensaios experimentais em equipamento existente no Laboratório de Conformação Mecânica da Faculdade de Engenharia Mecânica também foram realizados abrangendo as mesmas variáveis citadas para a simulação. Os dados obtidos nestes ensaios foram confrontados com os das simulações para se estudar as possíveis causas do defeito e também para se avaliar o grau de representatividade do processo pelo programa de simulação. Concluiu-se que sob o critério de análise da deformação máxima equivalente, à medida que se aumenta a redução relativa e diminuem-se o ângulo de conformação e a velocidade de processo aumenta-se a probabilidade de ocorrência dos defeitos internos. Tanto nas simulações como nos ensaios práticos, não se notou uma tendência definida para a variável temperatura com relação à sua influência na formação dos defeitos internos
Abstract: Cross-wedge rolling (CWR) is a metal forming process in which wedge shaped tools are assembled to rollers, and concave or convex plates. Despite the advantages of this process associated with high productivity and reduction of raw materials, the formation of an internal defect, called Mannesmann, requires a careful inspection of the rolled parts. This defect has its origin in the center of the rolled pieces and its causes are not yet fully identified. Based on the finite element method, numerical simulations of the CWR process in three dimensions were studied using the simulation software MSC Superform, in order to analyze the influence of some geometric (forming and stretching angles and relative reduction) and process (initial temperature and speed process) variables on the formation of this that is considered the main defect of the process. Tests were also performed in an experimental equipment available in the Mechanical Forming Laboratory of the School of Mechanical Engineering covering the same variables cited for the simulation. The data from these tests were confronted with simulation results to determine the possible causes of the defect and also to evaluate the agreement of these results. From the analysis of the maximum equivalent strain, the higher relative reduction and smaller forming angle and process speed values the higher probability that the internal defects occur. It was not noticed a good trend about the influence of the initial temperature on the formation of the internal defects
Doutorado
Materiais e Processos de Fabricação
Doutor em Engenharia Mecânica
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Lampreia, Ricardo Jorge Segurado. "QoS in LEO satellite networks with multipacket reception." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/11202.

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Dissertação apresentada para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia
Low Earth Orbit (LEO) satellite networks can improve terrestrial wireless networks to allow global broadband services for Mobile Terminals (MT), regardless of the users' location. In this context, hybrid telecommunication systems combining satellites with Long Term Evolution (LTE) networks, like the LightSquared technology, are intended to provide ubiquitous high-speed services. This dissertation analyses the performance of a random access protocol that uses Hybrid Network-assisted Diversity Multiple Access (H-NDMA), for a LEO satellite system network, named by Satellite Random NDMA (SR-NDMA). The protocol also considers a Single Carrier-Frequency Domain Equalization (SC-FDE) scheme for the uplink transmission and a Multipacket Reception (MPR) receiver. In this scenario, the transmission of data packets between MTs and the Base Station (BS) is made through random access and schedule access slots, organized into super-frames with the duration of a Round Trip Time (RTT). A SR-NDMA simulator is implemented to measure the system performance in matters of throughput, energy consumption, system delay and also the protocol capacity to meet Quality of Service (QoS) requirements. A set of simulations tests were made with a random Poisson process tra c generation to validate the analytical model. The capacity to ful l the QoS requirements of a real-time tra c class was also tested.
FCT/MEC: MPSat - PTDC/EEA-TEL/099074/2008, OPPORTUNISTIC CR - PTDC/EEA-TEL/115981/2009, Femtocells - PTDC/EEA-TEL/120666/2010 e ADIN - PTDC/EEI-TEL/2990/2012
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14

Wang, Bin-Yeong, and 王斌永. "Computer Simualtion Model of Broiler Growth." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/19466949159702924187.

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Abstract:
碩士
國立中興大學
畜牧學系
82
The purposes of this study were to investigate the mechanisms of response of broilers to the dietary nutrient intake and to build a computer simulation model of the broiler growth. This model was developed on a Stochastic method. The numerous related equations of published papers were compared. Through the nutrition and physiology, the need to meet nutrient requirements and utilization of broilers was studied and the model to predict voluntary feed intake and maximum feed intake used by broilers under various factors was built. This model was written in Quick BASIC computer programming language. Given feeding regime, diet composition, broiler type, housing condition, slaughter weight or slaughter days, the model predicts on a daily basis, feed intake, daily body weight gain, feed conversion ratio, energy and protein requirements for maintenance, energy cost for cold thermogenesis. The model also predicts retention of body composition and carcass sections. A finanical report is also produced. The model was validated by comparing with published experiments. The model could be act as a valuable reference for the further validation.
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15

Tsai, Meng-Chun, and 蔡孟駿. "A study of web-based construction simualtion tool." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/28876292553307255084.

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Abstract:
碩士
國立雲林科技大學
營建與物業管理研究所
97
Computer simulation has been widely used in various areas. In construction business, company can predict its cost and time consumed by computer simulation to realize the difficulties and the efficiency of resource usage. However, computer simulation application in construction is not popular even the capabilities has been proven in many researches. One of the main reasons is the complexity of the simulation software. Nevertheless, users are required to gain relative knowledge and trained-skills to write programs or build a computer module for specific application. Therefore, this research designs a Web-based platform, which is easily to operate for users, providing users to proceed construction simulation without any complicate process. To maximize its application, this system contains a standard civil engineering construction processing module that is important and easy to reach. Users do not need to rebuild a construction module, but adjust partial data depending on different cases. The framework of this research is based on a computer simulation software, called SIMPROCESS, to develop a simulation system. First of all, operation may input construction basic information, manpower, materials, number of machinery, and cost that is to provide construction business and company useful references, in the ASP.NET Web dynamic webpage of Visual Studio 2008. Second, operators are able to save all the data typed in the data file for the system managers to open and look up the data information by building a connection database and dynamic webpage with Access. Third, in order for the managers to read the Access for construction simulation and save the results in database for future use, operators use function the customize program of SIMPROCESS extended software with SQL data base language. The research implements the cases of the road and under bridge construction to validate the reliability and rationality of the system. The research is looking forward to enhance the function of computer simulation. It’s not only for the untrained users to save predicted time and cost, though out the transmission of internet, but also for users , as long as they learn how to browse the website, to easily control the simulation, to quickly acquire data and references for decision making.
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16

Schwede, Dirk Alexander. "Towards a Universal and Integrated Digital Representation of Physical Processes." 2006. http://hdl.handle.net/2123/1433.

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Abstract:
Doctor of Philosophy(PhD)
This thesis describes the exploration and the development of computational means to investigate the behaviour of design objects before they are available for investigation in the physical world. The motivation is to inform the design process about the design object’s performance in order to achieve better – more performance-oriented – design outcomes in the sense of energy efficiency and comfort performance than can be achieved by conventional design techniques. The research is structured into five successive parts. - Concept Development – A review of the objective domains comfort assessment and energy efficiency assessment is conducted and the design process, human design activity and the application of simulation in the architectural domain is discussed in order to identify requirements for the development of computational means for design analysis. Requirements regarding model content, model features and model integration are developed. The main requirements are that a highly integrated, three-dimensional and dynamic representation of physical processes is needed and that a universal and integrated representation is required. - Concept Formulation – Based on the identified requirements, the concept for a model is formulated. In order to achieve a universal and integrated representation of physical processes the concept uses the approach of a constructive language. Space is represented with autonomous spatial elements, called congeneric cells. Interaction between the cells is represented by near- and remote-conjunctions. Physical and geometric self-contained formulations of the model reduce the model input requirements, so that geometric information and simple property specification (material, activity) is sufficient to describe the design object in the model. - Model Development – The concept is formulated in mathematical physical terms based on well known physical laws and building physical models (first-principle approach). Heat and moisture conduction, diffusion of various components and a flow model is formulated as near-conjunction processes. Heat radiation, light and sound are modelled with a radiosity approach as remote-conjunctions. The simulation algorithm, which governs the interaction between the cells in order to represent the behaviour of space, is explained. - Computational Implementation – The concept and the model is tested by implementation of a prototype using C++ and OpenGL on a conventional Pentium 4 notebook. The prototype consists of three parts: user-interface, model translator and simulation engine. The user interface functions as model-input and result-output device. The implementation of the concept and of further model parts is described in detail. - Assessment and Testing – The developed concept and the model, as implemented in the prototype, are tested and assessed against the initially developed requirements. The physical model is assessed in regard to plausibility and accuracy of the representation of the physical phenomena. At the end of the thesis the project is summarized, the achievements of the project’s objectives are discussed critically and issues for future research are suggested. Possible applications of the developed model are listed, and the contributions to the application of computational simulation in the architectural domain, developed in this research, are named. At the current stage the required processing time and high memory requirements prevent implementation of a design assessment system, following the suggested concept, at a useful scale. Also the developed physical models require further refinement and testing. Although the general feasibility of the concept and the model was successfully demonstrated, its implementation in a fully applicable design assessment system based on the universal and integrated representation of physical processes was not achieved at this stage. While detailed description and analysis is given in the body of the thesis, detailed formulations of the work and the developed model are given in the appendix. The body and the appendix together provide a complete picture of the research presented.
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