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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.
81

Simulation und Analyse zur Ermittlung kinematischer Parameter für die CAE-gestützte Mechanismensynthese

Denninger, Daniel, Berger, Maik, Meyer, Torsten, Wallasch, Rainer 26 June 2013 (has links)
Charakterisierung eines textilen Halbzeuges aus Maschenstruktur Technologiedefinition zu einem ausgewählten Verfahren zum Erzeugen der Maschenstruktur Analyse und Simulation des Antriebskonzeptes einer Flachraschelmaschine Synchronisation technologiebedingter Fertigungsschritte und Ableiten von Randbedingungen für die Mechanismensynthese
82

Product Development Of License Plate Holder : In Collaboration With Koenigsegg Automotive AB

Gustavsson, Sofia, Oschmann, Adelina January 2023 (has links)
This report is being conducted in collaboration with Koenigsegg Automotive AB, a company founded in 1994 that manufactures mega cars. This study aims to design a license plate holder for their new car Jesko that comes in two models, Absolut and Track. The license plate holder is to be adapted to a specific country and their regulatory framework. The project also involves selecting materials and manufacturing processes in consultation with the industrial partner. The work has been divided into different stages, calculations, CAD modeling, analysis, and selection of materials and manufacturing processes. The CAD modeling is performed using Catia V5, while the analyses are conducted using SimSolid. The methodology used in this project is inspired by the method outlined in the book "Product Design and Development" by Karl T. Ulrich, Steven D. Eppinger, and Maria C. Yang. The method consists of six main steps: planning, research, customer needs, concept generation, concept selection, and detailed design. The result chose six different concepts being developed, analyzed, and compared. After identifying the most suitable concept, it is presented with a detailed product description of its design, materials, and manufacturing methods. This report is being conducted in collaboration with Koenigsegg Automotive AB, a company founded in 1994 that manufactures mega cars. This study aims to design a license plate holder for their new car Jesko that comes in two models, Absolut and Track. The license plate holder is to be adapted to a specific country and their regulatory framework. The project also involves selecting materials and manufacturing processes in consultation with the industrial partner. The work has been divided into different stages, calculations, CAD modeling, analysis, and selection of materials and manufacturing processes. The CAD modeling is performed using Catia V5, while the analyses are conducted using SimSolid. The methodology used in this project is inspired by the method outlined in the book "Product Design and Development" by Karl T. Ulrich, Steven D. Eppinger, and Maria C. Yang. The method consists of six main steps: planning, research, customer needs, concept generation, concept selection, and detailed design. The result chose six different concepts being developed, analyzed, and compared. After identifying the most suitable concept, it is presented with a detailed product description of its design, materials, and manufacturing methods.
83

Simulation of CamDrum for Shock Absorbers / Simulering av CamDrum för stötdämpare

Olsson, Adam, Rask, Anders January 2019 (has links)
Simulation can play an important role when aiming to streamline extensive and time-consuming tests. It has the potential to save time, money and energy. One of the testing methods used to test shock absorbers (SA), is accelerated life testing using a rolling road, CamDrum. It is therefore of great interest to examine the possibilities to streamline this testing method. This master thesis is conducted in co-operation with Öhlins Racing AB and the Machine Design department at KTH. The thesis project aims to look into the following: How can the use of simulation software aid in streamlining the test sequence used for shock absorbers in CamDrum? What limitations is there when simulating the CamDrum method using the selected simulation software? The goal was to develop an adequate model according to specified requirements, to facilitate early testing of new ideas and parameter changes. The delimitations includes, that the project only focuses the test-rig for MTB shock absorbers, the parts of the test-rig are assumed to be rigid and the simulation of the shock absorber is out of scope, since the aim of this thesis is to simulate the test-rig. To succeed with the project, a background research was conducted to gain knowledge about shock absorbers, test method and equipment, dynamics and useful software. The simulation model was verified against data obtained from tests. The tests were performed using the CamDrum with two different MTB shock absorbers and a stiff rod. The aim was to log and verify the change in position for the test-rig, shock absorbers and wheel. In addition the forces acting on the shock absorbers was investigated using strain gauges attached to the test-rig. The mean deviation in % for configuration 70-30-30 [mm] bump: SA MTBM1899, A4: 11.6% - 23.2%. SA MTB1691, A4: 15.8% - 28.1%. Stiff rod, A3: 0.9% - 4.9%, A5: 2.0% - 5.1%. SA Force, 16.1% - 24.0%. The deviation between the simulation and the test environment increases with the velocity. The use of stiff rod verifies the model against the CamDrum regarding the displacement. The resulting force from the use of strain gauges verifies the simulation models force regarding the shape. The Amesim model has the potential to be of great aid when designing tests. / Simulering kan vara en väg till att effektivisera tidskrävande och omfattande tester. Det finns potential att spara såväl energi som tid och pengar. En av metoderna för att testa stötdämpare är rullande landsväg, CamDrum. Det är därför intressant att undersöka hur den processen kan effektiviseras. Examensarbetet utförs i samarbete mellan Öhlins Racing AB och institutionen för Maskinkonstruktion på KTH. Det här examensarbetet avser att undersöka följande: Hur kan användandet av simuleringsprogram underlätta effektivisering av testmetoden som används för stötdämpare i CamDrum? Vilka avgränsningar finns vid användande av simulering för CamDrum-metoden med valt simuleringsprogram? Målet var att utveckla en modell som uppfyller givna krav och underlättar vid initieringsfasen för utveckling av tester för CamDrum. Projektets avgränsningar innebär att enbart riggen för MTBstötdämpare undersöks, alla ingående komponenter i testriggen antas styva och dämparmodellen som utvecklats är förenklad då målet är att simulera riggen för dämparen. För att lyckas med uppgiften har en förstudie genomförts för att samla nödvändig kunskap om stötdämpare, dynamik, testmetoden och lämplig mjukvara. Simuleringsmodellen verifieras mot data hämtat från utförda tester. Testerna utfördes i CamDrum med två olika MTB-stötdämpare och en rundstång med mål att logga och verifiera rörelser för riggen, stötdämpare och hjulet. Vidare har krafterna på stötdämparen undersökts med hjälp av trådtöjningsgivare monterade på testriggen. Medelavvikelsen i % för guppkonfigurationen 70-30-30 [mm]: SA MTBM1899, A4: 11.6% - 23.2%. SA MTB1691, A4: 15.8% - 28.1%. Rundstång, A3: 0.9% - 4.9%, A5: 2.0% - 5.1%. SA Force, 16.1% - 24.0%. Avvikelsen mellan simuleringen och testerna ökar med hastigheten. Användandet av rundstången verifierar modellen gentemot CamDrum med avseende på positionsförändring. Den resulterande kraften från användandet av trådtöjningsgivare verifierar simuleringsmodellen med avseende på form.  Amesim-modellen har en möjlighet att underlätta vid framtagning av tester.
84

Study of Forming of Composite Materials with Abaqus CAE and The Preferred Fiber Orientation (PFO) Model

Li, Yumeng January 2017 (has links)
No description available.
85

Exploring the Political Roles of Chinese Think Tanks: A Case Study of China's Three Gorges Project Decision-Making

Mi, Na 03 June 2008 (has links)
Since the establishment of People's Republic of China in 1949, Chinese think tanks have experienced significant development during the transformative process of China's political reform and modernization, and their influence has become more notable than before. However, think tanks historically have been given little attention by the public as well as social scientists in China, so scholarly study on Chinese think tanks is limited. This thesis explores the political roles and characteristics of Chinese think tanks by investigating the transformation and classification of Chinese think tanks from 1949 to the present. Furthermore, through a case study of one of the significant projects in contemporary China—the Three Gorges Project—this thesis examines the performance and influence of three Chinese nonpolitical think tanks—the Chinese Academy of Social Science (CASS), the Chinese Academy of Sciences (CAS), and the Chinese Academy of Engineering (CAE) on the process of government policy-making in China. Based on this analysis of Chinese think tanks, I draw the conclusion that professionalism and institutionalization are very urgent requirements for contemporary China's think tanks. / Master of Arts
86

Simulation of distributed windings using the insert technique

Hoang, Hue, Widerström, Matilda January 2019 (has links)
During the insert process when the windings of an electric motor are pushed into the stator slots, some detrimental phenomena can occur that affect the efficiency and life of the motor. To detect these phenomena and optimize the process, a simulation would be useful. An investigation of the possibility to perform a simulation, using an appropriate numerical method for the insert process of distributed windings in a permanent magnet synchronous motor, was performed. During the project, a literature study was carried out to investigate existing methods and key-parameters for the simulation of the process. Explicit finite element method has been shown to be a suitable numerical method for simulating another winding process. An explicit finite element analysis was performed with a simplified model of the stator, the wires, the transmission tool and the needles by using the software Abaqus/CAE. In order to reduce the computational time, beam elements were used to model the wires and the other parts as rigid bodies. The model accounted for example contact and provided numerical results. The result was a suitable model. However, it needs to be developed further.
87

Traitement de maquettes numériques pour la préparation de modèles de simulation en conception de produits à l'aide de techniques d'intelligence artificielle / A priori evaluation of simulation models preparation processes using artificial intelligence techniques

Danglade, Florence 07 December 2015 (has links)
Maitriser le triptyque coût-qualité-délai lors des différentes phases du Processus de Développement d’un Produit (PDP) dans un environnement de plus en plus concurrentiel est un enjeu majeur pour l’industrie. Le développement de nouvelles méthodes et de nouveaux outils pour adapter une représentation du produit à une activité du PDP est l’une des nombreuses pistes d’amélioration du processus et certainement l’une des plus prometteuses. Cela est particulièrement vrai dans le domaine du transfert de modèles de Conception Assistée par Ordinateur (CAO) vers des activités de simulations numériques. Actuellement, les méthodes et outils de préparation d’un modèle CAO original vers un modèle dédié à une activité existent. Cependant, ces processus de préparation sont des tâches complexes qui reposent souvent sur les connaissances des experts et sont peu formalisés, en particulier lorsque l’on considère des maquettes numériques riches comprenant plusieurs centaines de milliers de pièces. Pouvoir estimer a priori l’impact de la préparation de la maquette numérique sur le résultat de la simulation permettrait d’identifier dès le début le meilleur processus et assurerait une meilleure maitrise des processus et des coûts de préparation. Cette thèse a pour objectif de relever ce défi en utilisant des techniques d’intelligence artificielles capables d'imiter et de prévoir un comportement à partir d'exemples judicieusement choisis. L’idée principale est d’utiliser des exemples de préparation de maquettes numériques comme entrées d’algorithmes d’apprentissage pour configurer des estimateurs de la performance d’un processus. Lorsqu’un nouveau cas se présente, ces estimateurs pourront alors prédire a priori l’impact de la préparation sur le résultat de l’analyse sans avoir à la réaliser. Afin d'atteindre cet objectif, une méthode a été développée pour construire une base d’exemples représentatifs, identifier les variables d’entrée et de sortie déterminantes et configurer des modèles d’apprentissage. La performance d’un processus de préparation sera évaluée à l’aide de critères tels que des coûts de préparation, des coûts de simulation et des erreurs sur le résultat de l’analyse dues à la simplification des modèles CAO. Ces critères seront les données de sortie des algorithmes d’apprentissage. Le premier challenge de l’approche proposée est d’extraire les données des modèles 3D complétées par des données relatives au cas de simulation qui caractérisent au mieux un processus de préparation , puis d’identifier les variables explicatives les plus déterminantes. Un autre challenge est de configurer des modèles d’apprentissage capables d’évaluer avec une bonne précision la qualité d’un processus malgré un nombre limité d’exemples de processus de préparation et de données disponibles (seules les données relatives aux modèles CAO originaux, aux cas de simulation sont connues pour un nouveau cas). Au final, l’estimateur de la performance d’un processus aidera les analystes dans le choix d'opérations de préparation de modèles CAO. Cela ne les dispensera pas de la simulation mais permettra d'obtenir plus rapidement un modèle préparé de meilleure qualité. Les techniques d’intelligence artificielles utilisées seront des classifieurs de type réseaux de neurones ou arbres de décision. L’approche proposée sera appliquée à la préparation de modèles CAO riches pour l’analyse CFD. / Controlling the well-known triptych costs, quality and time during the different phases of the Product Development Process (PDP) is an everlasting challenge for the industry. Among the numerous issues that are to be addressed, the development of new methods and tools to adapt to the various needs the models used all along the PDP is certainly one of the most challenging and promising improvement area. This is particularly true for the adaptation of CAD (Computer-Aided Design) models to CAE (Computer-Aided Engineering) applications. Today, even if methods and tools exist, such a preparation phase still requires a deep knowledge and a huge amount of time when considering Digital Mock-Up (DMU) composed of several hundreds of thousands of parts. Thus, being able to estimate a priori the impact of DMU preparation process on the simulation results would help identifying the best process right from the beginning, and this will ensure a better control of processes and preparation costs. This thesis addresses such a difficult problem and uses Artificial Intelligence (AI) techniques to learn and accurately predict behaviors from carefully selected examples. The main idea is to identify rules from these examples used as inputs of learning algorithms. Once those rules obtained, they can be used as estimators to be applied a priori on new cases for which the impact of a preparation process can be estimated without having to perform it. To reach this objective, a method to build a representative database of examples has been developed, the right input and output variables have been identified, then the learning model and its associated control parameters have been tuned. The performance of a preparation process is assessed by criteria like preparation costs, analysis costs and the errors induced by the simplifications on the analysis results. The first challenge of the proposed approach is to extract and select most relevant input variables from the original and 3D prepared models, which are completed with data characterizing the preparation processes. Another challenge is to configure learning models able to assess with good accuracy the quality of a process, despite a limited number of examples of preparation processes and data available (the only data known to a new case are the data that characterize the original CAD models and simulation case). In the end, the estimator of the process’ performance will help analysts in the selection of CAD model preparation operations. This does not exempt the analysts to make the numerical simulation. However, this will get faster a simplified model of best quality. The rules linking the output variables to the input ones are obtained using AI techniques such as well-known neural networks and decision trees. The proposed approach is illustrated and validated on industrial examples in the context of CFD simulations.
88

L'entrepreneure salariée à la barre de son aventure entrepreneuriale : une course au large en solitaire ou en équipage ? : Analyse de l'engagement entrepreneurial par le concept Genre : le cas des coopératives d’activités et d’emploi (CAE) / Woman employee entrepreneur has the bar of his entrepreneurial adventure : solo ocean racing or crewed racing? : Analysis of entrepreneurial commitment by the genre concept : the case of Cooperatives of Activities and Employement(CAE)

Fontier, Virginie 15 December 2017 (has links)
A partir du constat d’un processus de féminisation des Coopératives d’Activité et d’Emploi (CAE) en France nous posons la question : pourquoi les CAE, qui sont des structures mixtes d’accompagnement à la création et au développement d’activité, attirent-elles plus les femmes ? Pour mieux comprendre ce phénomène nous « chaussons les lunettes » sociologiques avec les verres de « genre » afin d’analyser le processus d’engagement des femmes dans un parcours entrepreneurial dans les CAE. L’analyse de ce phénomène social avec les lunettes Genre permet de dépasser une vision idéalisée que nous pourrions avoir de l’innovation sociale que représente les CAE ainsi qu’une approche simplement critique de reproduction des inégalités sociales et sexuées pour aller vers une approche nuancée des expériences des entrepreneures salariées. Les CAE constituent une « opportunité professionnelle » pour des femmes engagées dans un processus de mobilité professionnelle suite à une impasse professionnelle et/ou un sentiment d’insatisfaction dans leur parcours. Ce besoin d’entreprendre « autrement » semble trouver une réponse auprès du statut hybride « d’entrepreneur salarié » et du cadre d’emploi qui y est proposé. Cependant, les femmes ne sont pas à égalité dans cette aventure car l’engagement entrepreneurial dans ses formes dépend des trajectoires biographiques frappées du sceau de genre. / At the starting point of process of feminization of the Cooperatives of Activities and Employement (CAE) in France we ask the question : why the CAE, wich are mixed structures of accompaniement to the creation and development of activity attract more women ? To better understand this phenomenon we « wear glasses » sociological with the glasses of « gender » in order to analyse the process of engagement of women in an entrepreneurial career in the CAE. The analysis of this social phenomenon with the gender glasses exceed an idealized vision that we could have social innovation that represents the CAE as a simply critical approach of reproduction of social and gender related inequalities toward an approach balanced experiences of women employed entrepreneurs. The CAE is a buisness opportunity for women engaged in a process of professionnal mobility following a professional deadlock and/or a feeling of dissatisfaction in their carieer. This need to undertake « differently » seems to find an answer to the hybrid status « salaried entrepreneur » and the employment framework that is proposed. However, women are not equal in this adventure because entrepreneurial commitment in its forms depends on the biographical trajectories hit the seal of gender.
89

Analýza nadzvukového proudění plynu v diferenciálně čerpané komoře elektronového mikroskopu / Analysis of the supersonic flow of gas in the differentially pumped chamber EREM

Matloch, Roman January 2013 (has links)
This work describes briefly electron microscopy issue and physical model of fluid flow. Then presented diploma thesis will be describing analysis and evaluation of the impact of supersonic flow on the pressure and density in the path of the primary electron beam in the differential pumping chamber. For analysis, evaluation and examination of the issue will be used CAD and CAE (Computer Aided Engineering) programs. At the same time it will be developed a methodology of calculation applicable to supersonic flow in the low pressure system at ANSYS CFX.
90

Strukturella förbättringar av en markstabiliseringsmast

Skog, Axel January 2021 (has links)
This report has examined the possibilities of stiffening and strengthening a ground stabilization mast, in a way that a small production company can manufacture. The soil stabilization technique in question is Jet-Grouting also called injection drilling, which involves drilling to the desired depth and then letting high-pressure water jets mixed with filling mass to erode the surrounding soil mass and form pillars below the ground surface. The study intends to explore the possibility of placing a simplified model in the simulation program ANSYS that uses the finite element method (FEM) to obtain its results. The product development method described by Karl T. Ulrich and Steven D. Eppinger in the book "Product Design and Development" is then used to produce improvement proposals that will strengthen the mast. The purpose of this study was to identify the strength of a ground stabilization mast and then produce and present an improvement proposal, based on the rotation head that is now mounted on the ground stabilization mast. This rotary head is named "RH24X HP 67 TS" and is produced by Eurodrill, and it generates a maximum torque of 24 kNm. The simulations on the mast with the given torque resulted in the highest stress of 158 MPa to which the mast body was exposed to. With the design that the mast current design, it entails a 2.3 factor of safety, which is considered acceptable since the recommended factor of safety for this type of heavy machine is about 2 (Khan, et al., 2016). When the torque was increased to the limit of the mast, i.e., when the factor of safety is close to 1, it resulted in a maximum torque of 54 kNm. Mounting a rotary head with a torque of 54 kNm is therefore not recommended due to the low safety margin that it would entail. Market research has been done and the proposals presented in this study presents similar manufactures and series as of the current rotary head. The recommended rotary heads come from the Eurodrill X-series and are called "RH32X HP 67 TS" and it produces a maximum torque of 32 kNm, alternatively "RH 4300 HP 48 TSS" which produces a torque of 34 kNm. The improvement proposals presented in this report are developed by evaluating the results of the simulations performed and then identifying the weakest areas. Then, based on the product development method, generate a proposal that can stiffen and strengthen the ground stabilization mast. The improvement proposal on the cradle showed with the rotary head "RH24X HP 67 TS" a 4.8 factor of safety, compared to the current cradle which has a 2.6 factor of safety, it is almost a doubling in strength. A new design of trusses was presented and resulted in a 35% increase in rigidity without the need to add any new material. This means that by re-examining the structure of the truss you can strengthen and possibly check the rigidity of the mast, which among other things leads to better manoeuvrability without any real extra costs being needed. / Denna rapport har undersökt möjligheterna att styva och styrka upp en markstabiliseringsmast på ett sätt som ett mindre produktionsföretag klarar av att tillverka. Markstabiliseringstekniken i fråga är Jet-Grouting även kallad injiceringsborrning, som går ut på att man borrar till önskat djup för att sedan låta högtrycksvattenjetstrålar blandat med fyllnadsmassa erodera den kringliggande jordmassan och bilda pelare under markytan. Studien ämnar utforska möjligheten med att placera en förenklad modell i simuleringsprogrammet ANSYS som använder finit elementmetod (FEM) för att få fram sina resultat. Därefter används produktutvecklingsmetoden som beskrivs av Karl T. Ulrich och Steven D. Eppinger i boken ”Product Design and Development”, för att ta fram förbättringsförslag som ska styrka upp masten.   Studien har haft som syfte att ta reda på hållfastheten hos en markstabiliseringsmast och sedan ta fram och presentera ett förbättringsförslag, utifrån det rotationshuvud som nu är monterat på markstabiliseringsmasten. Detta rotationshuvud har benämningen ”RH24X HP 67 TS” och är producerad av Eurodrill och genererar ett maximalt vridmoment på 24 kNm. Simuleringarna på masten med det givna vridmomentet resulterade i den högsta spänningen på 158 MPa som mastkroppen utsattes för. Med det utförande som masten är idag medför det en 2,3 säkerhetsfaktor, vilket är anses vara acceptabelt eftersom den rekommenderade säkerhetsfaktorn för denna typ av tungmaskin ligger på cirka 2 (Khan, et al., 2016).  När man sedan ökade vridmomentet till mastens bristgräns, det vill säga när säkerhetsfaktorn tangerar 1, resulterade det i ett maximalt vridmoment på 54 kNm. Att montera ett rotationshuvud med ett vridmoment på 54 kNm är därför inte att rekommendera på grund av den låga säkerhetsmarginalen som det skulle innebära. Därför presenteras förslag på rotationshuvuden som masten kan klara av, genom en marknadsundersökning gjord på liknade tillverkare och serier som dagens rotationshuvud. De rotationshuvud som rekommenderas kommer från Eurodrill X-serie och heter ”RH32X HP 67 TS” och den producerar ett maximalt vridmoment på 32 kNm, alternativt ”RH 4300 HP 48 TSS” som producerar ett vridmoment på 34 kNm.  Förbättringsförslagen som presenteras i denna rapport är framtagna genom att utvärdera resultaten av de utförda simuleringarna och sedan identifiera de svagaste områdena. Därefter genereras förslag utifrån produktutvecklingsmetoden som kan styva och stärka upp markstabiliseringsmasten. Förbättringsförslaget på släden visade med rotationshuvudet ”RH24X HP 67 TS” en 4,8 säkerhetsfaktor, jämfört med den nuvarande släden som har en 2,6 säkerhetsfaktor vilket är nästan en fördubbling i hållfasthet. En ny design av fackverk presenterades och resulterade i 35 % ökad styvhet utan att behöva addera något nytt material. Det innebär att man genom att ompröva fackverkets struktur kan stärka och eventuellt kontrollera mastens styvhet, vilket bland annat leder till bättre manövrerbarhet utan några egentliga extra kostnader behövs.

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