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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.
181

Projeto conceitual e análise de desempenho do sistema de admissão de ar em uma aeronave não convencional de combate / Conceptual design and performance analysis of the air intake system in a non-conventional fighter aircraft

Pedro David Bravo Mosquera 22 May 2017 (has links)
A concepção de aeronaves não convencionais a fim de alcançar um determinado desempenho ou melhoria operacional é sem dúvida um dos objetivos mais importantes da engenheira aeronáutica. Tais melhorias envolvem: redução de arrasto, redução da seção transversal, redução de ruído, redução da distância de decolagem e pouso, aumento da eficiência aerodinâmica, aumento da carga útil, entre outros. Por tanto, métodos de otimização multidisciplinar se tornaram em ferramentas muito úteis para aprimorar o projeto conceitual destas aeronaves. Neste contexto, este trabalho teve como objetivo o desenvolvimento do projeto conceitual de uma aeronave não convencional de combate e a análise de desempenho aerodinâmico do seu sistema de admissão de ar (Intake), tendo como principal característica, estar localizado na parte superior da fuselagem da aeronave (Dorsal Intake). O delineamento conceitual foi desenvolvido através da implementação de metodologias de otimização multidisciplinar de projeto (MDO) na fase de projeto paramétrico, integrando conceitos como: entropia estatística, desdobramento da função qualidade (QFD) e análise de restrições. Além disso, foram usados métodos analíticos e teóricos, ferramentas de desenho assistido por computador (CAD) e simulações da dinâmica dos fluidos computacionais (CFD) para otimizar e obter a configuração final da aeronave. Posteriormente, 5 configurações de asa delta foram selecionadas para avaliar as mudanças de desempenho do dorsal intake sob a influência aerodinâmica das superfícies principais da aeronave (Asa e Fuselagem), em regimes de voo subsônico (Mach = 0.4), transônico (Mach = 0.9) e supersônico (Mach = 1.7; 2) a diversos ângulos de ataque (De α = 10º a α = 30º ). Os resultados encontrados neste trabalho foram avaliados em separado, subsequentemente foram integrados, a fim de obter a nova concepção de aeronave não convencional de combate; a aplicação de MDO permitiu estimar as variáveis de projeto ideais para o desenvolvimento do projeto da aeronave, em relação a sua missão. Em contrapartida, os resultados da integração intake-estrutura mostram que apropriadas características de desempenho e compatibilidade foram mantidas durante as fases de voo subsônicas, para as 5 configurações de asa. No entanto, para velocidades transônicas, a configuração canard apresentou um acréscimo nos níveis de recuperação de pressão total, devido ao fluxo de alta energia na parte superior da fuselagem, o qual é produzido pelo vórtice do canard a moderados ângulos de ataque. Finalmente, para velocidades supersônicas, a asa com dispositivos LEX (Leading Edge Extensions) obteve os melhores níveis de recuperação de pressão total, pois a implementação destes dispositivos apresentou uma montagem mais vantajosa com sua fuselagem para gerar o cone de Mach, aumentando os níveis de recuperação de pressão total e reduzindo a distorção na face do motor. No entanto, para velocidades maiores a Mach = 2, sem importar a configuração de asa, a expansão do escoamento sobre a fuselagem e as asas da aeronave produziu um aumento no número Mach local na entrada do intake, o que reduziu os níveis de desempenho e compatibilidade do mesmo. Em consequência, a posição do intake na parte superior da fuselagem representa uma opção de configuração viável para aeronaves que requerem apenas capacidades de ângulo de ataque razoáveis, tais como aeronaves de caça ar-terra, sendo a asa com dispositivos LEX a geometria que representa melhores qualidades de desempenho na maioria dos 3 regimes de voo avaliados. / The conception of non-conventional aircraft with the aim of achieving a certain performance or operational improvement is undoubtedly, one of the most important objectives of the aeronautical engineering. These improvements involve: drag reduction, cross section reduction, noise reduction, shortening of take-off and landing distance, increase of aerodynamic efficiency, payload increase, among others. Therefore, optimization multidisciplinary methods became in very important tools to upgrade the conceptual design phase of these aircraft. In this context, this work had as aim the development of the conceptual design of a nonconventional fighter aircraft and the aerodynamic performance analysis of its air intake, having as main characteristic to be located at the top of the fuselage (Dorsal Intake). The conceptual design was developed through the implementation of multidisciplinary design optimization (MDO) methods in the parametric design phase, integrating concepts of: statistical entropy, quality function deployment (QFD) and constraint analysis. Besides that, it was used analytical and theoretical methods, computer-aided design (CAD) tools and computational fluid dynamics (CFD) simulations to optimize and obtain the final aircraft configuration. Subsequently, 5 delta wing configurations were selected to evaluate the dorsal intake performance changes under the aerodynamic influence of the main aircraft surfaces (Wings and Fuselage) in subsonic (Mach = 0.4), transonic (Mach = 0.9) and supersonic (Mach = 1.7; 2) flight regimes, at various angles of attack (From α = 10º to α = 30º ). The results found in this work were evaluated separately, later these were integrated, in order to get the new conception of non-conventional fighter aircraft; the MDO application allowed to estimate the ideal design variables for developing the aircraft design, regarding to its mission. On the other hand, the results of the intake-structure integration shown that appropriate performance and compatibility characteristics were maintained during the subsonic flight stages for the 5 wing configurations. However, for transonic velocities, the canard configuration presented an increase in the total pressure recovery levels, due to the high energy flux on the fuselage, which is produced by the canard vortex at moderate angles of attack. Finally, for supersonic velocities, the wing with LEX (Leading Edge Extensions) devices got the best levels of total pressure recovery, because the implementation of these devices presented a more advantageous assembly with its fuselage to generate the Mach cone, increasing the total pressure recovery levels and reducing the distortion at the engine face. However, for velocities higher than Mach = 2, regardless the wing configuration, the flow expansion on the fuselage and the wings produced an increase in the local Mach number in the intake entrance, which reduced the performance and compatibility levels of it. As a consequence, the top mounted intake position represents an option of viable configuration to aircraft that require only reasonable angles of attack capabilities, such as air-to-ground fighter aircraft, being the wing with LEX devices the geometry that represents better performance qualities in the majority of the 3 evaluated flight regimes.
182

Prodlužovač dojezdu elektromobilu / Range extender of an electric vehicle

Jelínek, David January 2020 (has links)
This thesis describes the design of a four-stroke engine with two cylinders, using as a range extender. The first chapter briefly introduces the company Škoda Auto a.s., for which the range extender was designed. Also, there is a list of the available electric and hybrid vehicles manufactured by this company. The next chapter deals with the division of hybrid vehicles, as an intermediate step for the use of electric vehicles, the reason for their use and the definition of advantages and disadvantages of hybrid vehicles. Also, the range extender technology is described here. The third chapter contains a description of the conceptual design of the range extender and describes the design and balancing of the crankshaft in more detail. The last chapter describes the calculation of the crankshaft dynamics and the individual parts load. The resulting crankshaft safety is determined by comparing the calculated values with a series-produced 1.0 MPI evo engine, which is the base of the described range extender.
183

Simulační studie robotické linky pro obsluhu obráběcího stroje a realizaci dokončovacích operací / A simulation study of a robotic cell for production machine operation and realization of finishing operation

Kljajič, Marko January 2020 (has links)
The aim of the thesis is conceptual design of robotic workplace with its subsequent simulation. The current workplace for manufacturing and deburring parts for automotive industry is operated manually. The plan is overall automation and replacement of operators by robots. The thesis deals with the concept of layout of elements in the cell, and the procedure of their selection or design. Process simulation is performed in the Process Simulate software from Siemens. For the purposes of the work is used RCS module, which on the basis of dynamic conditions can calculate the cycle of production very close to the reality. The production cycle is compared to the current workplace. The work also deals with the economic evaluation of the proposed workplace.
184

Conceptual Design of a South Pole Carrier Pigeon UAV

Dlima, Kendrick M 01 June 2020 (has links)
Currently, the South Pole has a large data problem. It is estimated that 1.2 TB of data is being produced every day, but less than 500 GB of that data is being uploaded via aging satellites to researchers in other parts of the world. This requires those at the South Pole to analyze the data and carefully select the parts to send, possibly missing out on vital scientific information. The South Pole Carrier Pigeon will look to bridge this data gap. The Carrier Pigeon will be a small unmanned aerial vehicle that will carry a 30 TB solid-state hard drive from the South Pole to various destinations in the Southern Hemisphere, but it has been designed to y to Christchurch, New Zealand. This 87 lb. UAV will be able to y 3,650 nmi. up to 25,000 ft., using a 5.7 hp. engine. It will feature an de-icing system on the leading edge of its 8 ft. span wing to allow it to y through cold, moist climates. It will have a 39 in. long fuselage with a tail boom of 33 in. The aircraft has been designed to be made out of composites, thus reducing both the weight of the aircraft as well as its drag. It has been designed to come apart in order to be shipped successfully to the South Pole. There, it will be assembled and launched via a custom pneumatic launcher. It will y autonomously to 15,000 ft. and cruise climb throughout the flight to 25,000 ft., before descending to its destination. There, it will be caught by a net restraint system, where the hard drive will be extracted. The Carrier Pigeon is truly a unique vehicle for its size, range, and robustness.
185

An Integrated Approach towards Model-Based Mechatronic Design

Qamar, Ahsan January 2011 (has links)
Mechatronic design is an enigma. On the one hand, mechatronic products promise enhanced functionality, and better performance at reduced cost. On the other hand, optimizing mechatronic design concepts is a major challenge to overcome during the design process. In the past, less attention has been paid to the life phases of a mechatronic product, and it was assumed that modifications in electronics and software will ensure that the product performs to expectation throughout its life time. However it has been realized that introducing design changes in mechatronics is not easy, since it is difficult to assess the consequences of a design decision, both during the design process of a new product, and during a design modification. It is also realized that there is a strong need to consider the product's life phases during the early phases of product development. Furthermore, it is rather difficult to perform a design optimization since it requires introducing changes across different domains, which is not well supported by the methods and tools available today. This thesis investigates the topic of mechatronic design and attacks some of the major challenges that have been identified regarding the design of mechatronic products. The goal is to provide support to the designers to facilitate better understanding of the consequences of their design choices as early as possible. The work also aims to provide support for assessing alternative design concepts, and for optimizing a design concept based on requirements, constraints and designer preferences at the time of design. The thesis highlights three main challenges related to mechatronic product development: the need for a common language during conceptual design; the inadequate information transfer between engineering domains; and the difficulty in assessing the properties of competing mechatronic concepts. A model-based integration approach is presented, and these key challenges are considered in relation to an integrated modeling and design infrastructure. The approach is illustrated through the design of two mechatronic systems- a two degrees-of-freedom robot, and a hospital bed propulsion system. Initial results provide evidence of good potential for information transfer across mechatronic domains. Although SysML was used for the case studies, some important questions were raised about its suitability as a common language for mechatronics. Suggestions for future work are: to utilize the developed infrastructure and incorporate a capability to model and assess consequences of competing design concepts; provide support for optimizing these concepts; and evaluate the usefulness of the developed infrastructure in a real-world design setting. These efforts should provide ample information to the designer for making adequate decisions during the design process. / QC 20110629
186

Modélisation analytique du couplage multi-physique magnétique-thermique dans la phase de préconception d'un système mécatronique / Analytical modeling of the multi-physical magnetic-thermal coupling in the conceptual design phase of a mechatronic system

Ben messaoud, Yethreb 17 December 2018 (has links)
Durant la phase de conception, les différentes équipes d’ingénierie procèdent à de multiples simulations par éléments finis traitant les comportements physiques variés afin d’assurer la vérification et la validation.Cependant, les résultats insatisfaisants engendrent des changements tardifs et par conséquent de longues itérations et des coûts croissants.Pour répondre à cette problématique, il est essentiel de prendre en considération les contraintes géométriques et multi-physiques dès la phase de préconception.En effet, un processus appelé SAMOS est développé visant à sélectionner l’architecture multi-physique 3D la plus adéquate tout en garantissant une collaboration efficace entre les équipes d’ingénieurs. D’ailleurs, il est basé sur deux extensions en SysML permettant l’enrichissement de l’architecture par des informations géométriques et multi-physiques.D’autre part, cette thèse se focalise sur l’étude des contraintes magnétiques et du couplage magnétique-thermique.Comme cette phase ne supporte pas les simulations par éléments finis, les modèles analytiques basés sur des géométries simplifiées sont suffisants pour fournir des résultats approximatifs satisfaisants.Dans ce contexte, différents modèles analytiques sont étudiés et validés à travers des simulations par éléments finis et des mesures pour plusieurs cas tels que les aimants permanents en Néodyme. En fait, l’augmentation de température ne fait pas seulement diminuer la densité du flux magnétique rémanente mais il est capable de causer des pertes irréversibles. En effet, lorsqu’on revient à la température initiale, les caractéristiques de l’aimant sont modifiées. Les différents facteurs affectant le processus de démagnétisation sont examinés.De plus, l’impact de la température sur les performances d’un moteur sans balais est étudié étant donné que ce dispositif représente un système mécatronique complexe. / During the design phase, the different engineering teams make multiple FE simulations dealing with various physical behaviours in order to ensure both verification and validation.However, the unsatisfactory results lead to late changes and hence to long iterations and increasing costs.In order to tackle this problem, it is essential to take into account the geometrical and multi-physical constraints in the complex system architecture since the conceptual design phase.In fact, a process called SAMOS is developed aiming at selecting the most adequate 3D multi-physical architecture while ensuring an efficient collaboration between the engineering teams. Moreover, this framework is based on two SysML extensions which allow the enrichment of the architecture with geometrical and multi-physical data.Furthermore, this thesis focuses on magnetic constraints and magnetic-thermal coupling.Since this phase does not support long FE simulations, the analytical models based on simplified geometries are sufficient to provide satisfactory approximate results.In this context, different analytical models are studied and validated through FE simulations and measures for several cases such as NdFeB permanent magnets. Indeed, the temperature rise does not only decrease the remanent flux density but is able also to cause irreversible losses. In fact, once we go back to the initial temperature, the characteristics of the magnet are modified. The different factors impacting the demagnetization process are discussed.Besides, the temperature impact on brushless motors’ performances is studied since this device represents a complex mechatronic system.
187

Diagnostický průzkum objektu historické budovy / Structural diagnostics of the historical building construction

Řezáčová, Veronika January 2012 (has links)
This thesis deals with the methodology, implementation and evaluation of diagnostic work units and structural elements of the historic schoolhouse building. Includes a static assessment of the horizontal structure and conceptual design layout adjustments for potential revitalization in case the object.
188

LHCb Upstream Tracker box : Thermal studies and conceptual design

Mårtensson, Oskar January 2016 (has links)
The LHC (Large Hadron Collider) will have a long shut down in the years of 2019 and 2020, referred to as LS2. During this stop the LHC injector complex will be upgraded to increase the luminosities, which will be the first step of the high luminosity LHC program (which will be realized during LS3 that takes place in 2024-2026). The LHCb experiment, whose main purpose is to study the CP-violation, will during this long stop be upgraded in order to withstand a higher radiation dose, and to be able to read out the detector at a rate of 40MHz,compared to 1MHz at present. This change will improve the trigger efficiency significantly. One of the LHCb sub-detectors the Trigger Tracker (TT), will be replaced by a new sub-detector called UT. This report presents the early stage design (preparation for mock-up building) of the box that will be isolating the new UT detector from the surroundings and to ensure optimal detector operation. Methods to fulfill requirements such as light and gas tightness, Faraday-cage behavior and condensation free temperatures, without breaking the fragile beryllium beam pipe, are established. / LHC (Large Hadron Collider) kommer under åren 2019-2020 att ha ett längre driftstopp. Under detta driftstopp så kommer LHC's injektionsanordningar att uppgraderas för att kunna sätta fler protoner i circulation i LHC, och därmed öka antalet partikelkollisioner per tidsenhet. Denna uppgradering kommer att vara första steget i "High Luminocity LHC"-programmet som kommer att realiseras år 2024-2026. LHCb-experimentet, vars främsta syfte är att studera CP-brott, kommer också att uppgraderas under stoppet 2019-2020. Framför allt så ska avläsningsfrekvensen ökas från dagens 1MHz till 40MHz, och experimentet ska förberedas för de högre strålningsdoser som kommer att bli aktuella efter stoppet 2024-2026. En av LHCb's deldetektorer, TT detektorn, kommer att bytas ut mot en ny deldetektor som kallas UT. Den här rapporten presenterar den förberedande designen av den låda som ska isolera UT från dess omgivning och försäkra optimala förhållanden för detektorn. Kraven på den isolerande lådan och tillvägagångssätt för att uppfylla dessa krav presenteras. / LHCb, LS2 and LS3 Upgrade
189

A novel approach for the development of policies for socio-technical systems

Taeihagh, Araz January 2011 (has links)
The growth in the interdependence and complexity of socio-technical systems requires the development of tools and techniques to aid in the formulation of better policies. The efforts of this research focus towards developing methodologies and support tools for better policy design and formulation. In this thesis, a new framework and a systematic approach for the formulation of policies are proposed. Focus has been directed to the interactions between policy measures, inspired by concepts in process design and network analysis. Furthermore, we have developed an agent-based approach to create a virtual environment for the exploration and analysis of different configurations of policy measures in order to build policy packages and test the effects of changes and uncertainties while formulating policies. By developing systematic approaches for the formulation and analysis of policies it is possible to analyse different configuration alternatives in greater depth, examine more alternatives and decrease the time required for the overall analysis. Moreover, it is possible to provide real-time assessment and feedback to the domain experts on the effect of changes in the configurations. These efforts ultimately help in forming more effective policies with synergistic and reinforcing attributes while avoiding internal contradictions. This research constitutes the first step towards the development of a general family of computer-based systems that support the design of policies. The results from this research also demonstrate the usefulness of computational approaches in addressing the complexity inherent in the formulation of policies. As a proof of concept, the proposed framework and methodologies have been applied to the formulation of policies that deal with transportation issues and emission reduction, but can be extended to other domains.
190

Methodological investigations into design inspiration and fixation experiments

Leite de Vasconcelos, Luis Arthur January 2017 (has links)
Designers often look for inspiration in their environment when exploring possible solutions to a given problem. However, many studies have reported that external stimuli may constrain designers’ imagination and limit their exploration to similar solutions, a phenomenon described as design fixation. Inspiration and fixation effects are traditionally studied with a similar experimental paradigm, which has produced a complex web of findings and explanations. Yet, when analysing the experiments and their findings closely, it becomes clear that there is considerable variation in how studies are conducted and the results they produce. Such variation makes it difficult to formulate a general view of how external stimuli affect the design process, and to translate the research findings into education and practice. Moreover, it raises questions about the reliability and effectiveness of the traditional experimental method. This thesis reports on a collection of studies that examine how design inspiration and fixation research is done and how it can be improved. It explores the research area by reviewing the literature and analysing data from a workshop; describes the research method by scrutinising experiments and their procedures; and explains the variation in research findings by testing experimental procedures empirically and suggesting new interpretations. My main findings are that: abstract stimuli can inspire or fixate designers to different degrees depending on how explicitly the stimuli are represented; external stimuli can inhibit the exploration of ideas that would otherwise be explored; the effect of experimental instructions varies depending on how encouraging the instructions are; and the way participants represent and elaborate ideas can moderate fixation results. Whilst this thesis offers insights into design practice and education, its main contribution is to design research, where it represents a fundamental material for those who are new to inspiration and fixation research, and for those who are already expert.

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