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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

Digital Tools for Product Development and Organizational Management

HABIB, MD.AHASHAN, SULTAN LIPOL, LEFAYET January 2010 (has links)
The report illustrates about the digital tools those are used for product development and organizational management (apparel sector). We went to Lectra Sweden AB, DTS solutions AB to search our planned information about those tools. We got some additional information from them as well. We were interested to learn about much software for this but we studied about Lectra Fashion PLM, PISA PDM, and ERP Garp system (CRM, SRM, MRM) as we could manage opportunity to know about them only.For Lectra, we focused on general idea about this software, its different divisions, its working procedure, its advantage to use, its possibility to use for every company. On the other hand, we concentrated on almost similar way of Lectra for PDM, PLM, ERP (CRM, SRM, and MRM).We got different divisions of Lectra, namely- Kaledo, Modaris, Diamino, Optiplan are using for various purposes, like - design, pattern making, marker making, spreading and cutting. On the opposite side of the coin, if companies implement PDM, PLM and ERP system, they can assist to manage the whole business chain very easily for instance- product development, order, purchase, manufacturing, stock/distribution, economy, logistics etcetera. We also knew that it is expensive to buy those software’s and require special skill to operate so it is not prolific to all company. / Program: Magisterutbildning i Applied Textile Management
82

Gestion des messages de sécurité dans les réseaux VANET. / Handling Safety Messages in Vehicular Ad-HocNetworks (VANETs)

Bouchaala, Younes 21 December 2017 (has links)
Les exigences de Qualité de Service (QoS) des applications VANET varient selon la nature et le type de l’application. Par conséquent, un protocole de communication VANET doit pouvoir répondre aux diverses exigences de QoS selon le type du trafic. Dans VANET, le canal de transmission est partagé par tous les véhicules en utilisant une même fréquence radio. Une mauvaise exploitation du canal peut donc conduire à des collisions et peut aussi engendrer un gaspillage de la bande passante. Un protocole MAC doit être alors conçu pour partager le canal entre les différents noeuds d’une manière efficace et équitable.Dans cette thèse nous présentons les contributions suivantes :1- Analyse et amélioration de la diffusion dans la norme IEEE 802.11.2- Optimisation de la technique CSMA pour des réseaux 1D et 2D.3- Développement d’un algorithme CSMA de transmission adaptatif qui met à jour le taux de détection de la porteuse en fonction d’une valeur de référence.4- Étude du gain obtenu par l’utilisation d’antennes directionnelles pour Aloha, Aloha non-slotté, et CSMA. / Quality of Service (QoS) requirements for VANET applications vary depending on the nature and type of the application. Therefore, a communication protocol in VANETs must be able to meet various QoS requirements according to the type of traffic. In VANET, the transmission channel is shared by all the vehicles using the same radio frequency. A poor exploitation of the channel can therefore lead to collisions and wasted bandwidth. A MAC protocol must therefore be designed to share the channel between the different nodes in an efficient and fair way.In this thesis we present the following contributions:1- Analysis and improvement of diffusion in the IEEE 802.11 standard.2- Optimization of the CSMA technique for 1D and 2D networks.3- Design of an adaptive transmission algorithm that updates the Carrier Sense threshold to reach a target value.4- Study the gain obtained by the use of directional antennas for Aloha, non-slotted Aloha, and CSMA.
83

Implementação de sistema CAD/CAM na empresa Francisco Andrade - Metalomecânica

Andrade, Valter Guedes de January 2010 (has links)
Tese de mestrado integrado. Engenharia Metalúrgica e de Materiais. Faculdade de Engenharia. Universidade do Porto. 2010
84

Desenvolvimento de um dispositivo para avaliação dimensional de um processo de fabrico de implantes dentários

Carvalho, João Diogo Cardoso de January 2013 (has links)
Trabalho realizado na empresa BringConcept, orientado pelo Prof. Dr. Casimiro de Andrade / Tese de Mestrado Integrado. Engenharia Metalúrgica e de Materiais. Faculdade de Engenharia. Universidade do Porto. 2013
85

Fabrication assistée par ordinateur pour le procédé EBM / Computer aided manufacturing for electron beam melting manufacturing

Béraud, Nicolas 05 October 2016 (has links)
Le procédé de fabrication par fusion de poudre à l'aide d'un faisceau d'électrons est appelé procédé Electron Beam Melting (EBM). Il permet la fabrication de pièces métalliques à partir de poudres. Grâce au niveau de qualité (géométrique et mécanique) des pièces produites, le procédé peut être utilisé afin de produire des pièces fonctionnelles et non plus uniquement des prototypes. Ce procédé, ainsi que les autres procédés additifs métalliques, permettent d'envisager le passage de l'impression 3D à la fabrication additive métallique.L'utilisation de la fabrication additive dans un contexte industriel impose le respect de critères en termes de qualité, coût et délai des pièces produites. L'ensemble des étapes numériques de mise en production d'une pièce constitue la chaîne numérique. Cette dernière a un impact fort sur l'ensemble de ces trois critères. Ainsi, cette thèse apporte une réponse à la question suivante :Comment la fabrication assistée par ordinateur peut-elle améliorer le triptyque qualité, coût, délai du procédé de fabrication EBM?Le problème est abordé par la question sous-jacente suivante :Quelles caractéristiques doit posséder un environnement de fabrication assistée par ordinateur adapté au procédé EBM ?Pour répondre à cette question, la chaîne numérique actuelle est analysée . Les principales limites identifiées sont :- l'utilisation de fichiers au format STL- l’impossibilité d’optimiser le procédé à différentes échelles- l’impossibilité de simuler le procédé EBMAfin de résoudre l'ensemble des problèmes énoncés, un environnement de FAO est proposé. Celui-ci permet de centraliser l'ensemble des opérations de mise en production au sein d'un environnement unique. Il autorise le travail avec l'ensemble des formats de fichiers reconnus comme les formats natifs des logiciels de CAO ou le format STEP. Des développements informatiques permettent de concrétiser l’environnement proposé.L'implémentation de l'environnement de FAO a mis en évidence le rôle fondamental de la simulation au sein de celui-ci. Il a donc fallu répondre à la question :Comment obtenir une simulation du procédé EBM permettant sa mise au point hors ligne en temps raisonnable ?Bien que la simulation du procédé EBM est largement traitée dans la littérature scientifique, les études proposées reposent sur la méthode des éléments finis et le temps de calcul nécessaire n'est pas compatible avec une utilisation au sein d'un environnement de FAO. Un type de simulation alternatif a donc été créé : une simulation par abaques. Elle est constituée d’une simulation par la méthode des éléments finis qui permet d'obtenir des cartes de températures pour des cas de chauffes et de refroidissements standards. Ces cartes de températures sont ensuite transformées en abaques. La simulation par abaques est vue comme la succession d'une multitude de cas standards. Ainsi l'algorithme de simulation par abaques cherche l'abaque le plus proche de la situation simulée, afin d’estimer les températures au pas de temps suivant.Cette méthode de simulation a permis une réduction des temps de calcul tout en gardant une précision suffisante pour pouvoir être utilisée pour optimiser les paramètres de fabrication.Grâce à une telle simulation, un outil d'optimisation des stratégies de fusion a pu être créé. Il permet d’améliorer la qualité des pièces produites en calculant des stratégies de fusion respectant certains critères thermiques.Les apports majeurs de ces travaux de thèses sont :- l'établissement d'un cahier des charges pour une chaîne numérique performante en EBM- le développement d'un environnement de FAO adapté au procédé EBM- la mise au point d'une simulation rapide du procédé EBM basée sur des abaques- la création d'un outil d'optimisation des stratégies de fusion / The Electron Beam Melting (EBM) process allows to build metallic parts from powder. Thanks to the geometric and mechanical quality of the parts produced, the EBM process can be used to manufacture functional parts and not only prototypes. This process, with other additive metallic processes, make it possible to consider a transition from 3D printing to metallic additive manufacturing.The use of additive manufacturing in an industrial environment requires compliance with quality, cost and time criteria for the parts produced. The production of manufactured parts involves a series of numerical stages which is called the numerical chain. The numerical chain has a significant impact on the three criteria mentioned above. Thus, this thesis provides an answer to the following question:How Computer Aided Manufacturing can improve the quality, cost and time of the EBM manufacturing process?This problem is addressed through the following underlying question:What are the required characteristics for a Computer Aided Manufacturing system adapted to the EBM process?In order to answer this question, the current numerical chain is analyzed. Three main limitations are found:- the use of STL files format- the process cannot be optimized at different scales- the process cannot be simulatedTo solve these issues, a CAM environment is proposed. It allows the centralization of all numerical operations in a single environment. All supported formats can be used within this environment, such as native CAD file formats or STEP format. Software developments are done to prove the feasibility of such an environment.The CAM environment implementation reveals the crucial role of simulation in this system. It is therefore necessary to answer this second question:How to obtain an EBM process simulation allowing the development of parameters, virtually?Although EBM simulation is a recurrent subject in scientific literature, existing studies are based on the finite elements method but the calculation time needed is too important to be used in an CAM environment. Thus, an alternative type of simulation is created in this thesis: a simulation based on abacus. It is composed of a finite elements model, that allows heat maps generation for standards cases of heating and cooling. These heat maps are then transformed in abacus. The simulation algorithm based on abacus search the nearest abacus from the simulated situation in order to estimate the temperatures at the next time step.This simulation method was used to reduce the calculation time while keeping a sufficient precision to optimize process parameters.With the simulation based on abacus, a tool for the optimization of melting strategies is developed. This tool allows quality improvement for the produced parts through the calculation of melting strategies according to thermic criteria.To summarize, the main contributions of this work are:- the definition of requirements specifications of a powerful numerical chain for the EBM process- the development of a CAM environment adapted to the EBM process- the proposal of a fast simulation for the EBM process, based on abacus- the development of a tool for the optimization of melting strategies
86

Optimised part programs for excimer laser-ablation micromachining directly from 3D CAD models

Mutapcic, Emir, n/a January 2006 (has links)
Fabrication of a 3D structure and surface texture using excimer laser mask projection ablation processes typically requires the machine operator to develop a specific NC part program for the desired structure geometry, and also incorporate appropriate machine parameters to achieve the desired surface finish. The capability of the laser ablation process could therefore be significantly improved by developing a CAD/CAM system that automatically generates the NC part program using the 3D information of the CAD model of the desired structure. Accordingly, the focus of this research was to develop such a system that is, an effective CAD/CAM system specifically for excimer laser mask projection micromachining tools. To meet these requirements, a unique combination of commercially available systems was used to develop the new CAD/CAM system. The systems used comprised of a computer aided, feature based parametric design system (SolidWorks), together with its extended programming capabilities based on Automated Programming Interface (API) functions for Windows applications, and Visual Basic (VB) 6.0 programming utilities. The system's algorithms use a novel methodology to extract the 3D geometry of a microstructure. Two different techniques have been developed to extract the 3D data. First, where 3D geometry information from a CAD model was defined as a Stereolithography (STL) file, and second, where this information has been contained in a set of bit-map (BMP) files that represent a sliced or layered structure of a CAD model. Based on this, first an algorithm to create NC part programs to support Step-and-repeat micromachining technique was developed and then successfully extended to be applicable for another commonly used micromachining method, Workpiece-Dragging technique. The systems algorithms for both techniques are based on the raster-colour programming technique, resulting in substantially reduced mathematical complexity and computational time. This is the first time this approach has been used to support direct conversion of 3D geometry from a CAD model into an NC part program compatible with the excimer laser CNC controller. 2D mathematical models for controlling edge and stitching errors were also implemented in the system. An additional technique, named as 'Common Nest' has been developed with the aim to enable automatic NC part programming when microstructure design to be completed successfully, requires use of multiple complex mask patterns as a projection tool instead of just a single square aperture. The effectiveness of the system was verified by NC part program generation for several 3D microstructures and subsequent machining trials using polycarbonate (PC) and Polyethylene terephthalate (PET), and optimised processing parameters. Excellent agreement was obtained between the laser machined geometries and the microstructure CAD models. The Laser Scanning Confocal Microscope (LSCM) measured the lateral dimensions tolerance of 2m. The system was also successfully applied for a practical micro-engineering application, for the development of a microfluidics cell transportation device.
87

Method to off-line program robotized metal deposition

Berg, Jonas, Luukkonen, Jarmo January 2007 (has links)
<p>This report is a ten credit degree project and is aimed at technically skilful personnel at Volvo Aero Corporation and at the University West. The goal of the project is to create a robot program that can manufacture a part by Metal Deposition from a 3-D CAD model (Unigraphics) via a CAM module and a CAR program (IGRIP) to an ABB robot. Metal Deposition is a method to build new parts, add material to an existing part and repair components that have been damaged in earlier processes. The method can be used with different kinds of welding with powder or welding wire as the additive material. Three reference geometries were used; two bosses and a circular sweep. UG/CAM is used to create the CLS (Cutter Location Source) data. Different milling operations are used to emulate welding.The program which imports the coordinates from the CLS data to IGRIP, as well as the export program, was written in GSL (Graphics Simulation Language). GSL is a Pascal-like programming language used to control the behaviour of simulation models. The import program reads linear movement coordinates line by line until the whole CLS file has been converted into IGRIP. UG/CAM should only use linear movement when using this program. If circular movements are used, a feature that converts those has to be added to the import program.</p>
88

Automatic geometric data migration throughout views of a model fidelity family /

Soderquist, Hans Lars, January 2006 (has links) (PDF)
Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2006. / Includes bibliographical references (p. 65-67).
89

Feature based reverse engineering for thermoforming mould design /

Tam, Ka-wing. January 2006 (has links)
Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.
90

Method to off-line program robotized metal deposition

Berg, Jonas, Luukkonen, Jarmo January 2007 (has links)
This report is a ten credit degree project and is aimed at technically skilful personnel at Volvo Aero Corporation and at the University West. The goal of the project is to create a robot program that can manufacture a part by Metal Deposition from a 3-D CAD model (Unigraphics) via a CAM module and a CAR program (IGRIP) to an ABB robot. Metal Deposition is a method to build new parts, add material to an existing part and repair components that have been damaged in earlier processes. The method can be used with different kinds of welding with powder or welding wire as the additive material. Three reference geometries were used; two bosses and a circular sweep. UG/CAM is used to create the CLS (Cutter Location Source) data. Different milling operations are used to emulate welding.The program which imports the coordinates from the CLS data to IGRIP, as well as the export program, was written in GSL (Graphics Simulation Language). GSL is a Pascal-like programming language used to control the behaviour of simulation models. The import program reads linear movement coordinates line by line until the whole CLS file has been converted into IGRIP. UG/CAM should only use linear movement when using this program. If circular movements are used, a feature that converts those has to be added to the import program.

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