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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.
1

Building a new production line : Problems, pitfalls and how to gain social sustainability

Telander, Andreas, Fahlgren, Jessica January 2015 (has links)
This thesis has been performed in collaboration with Volvo Cars Engine in Skövde, Sweden and Zhangjia-kou, China in order to receive a bachelor degree in automation engineering from the University of Skövde. The project focuses on analyzing the capacity of a future production line by using discrete event simulation. The production line is built in two different discrete event simulation software, FACTS analyzer and Plant Simulation. The focus of the study will be to compare the output results from the two software in order to give recommendations for which software to use in similar cases. This is done in order for Volvo Cars Corporation to have as a basis for further work in similar cases. The aim of the work is to verify the planned capacity of the new production line and to perform a leadership study with Chinese engineers in order to find out how they view the Swedish leadership and how this can be adapted to China and the Chinese culture and give recommendations for future work. The results of the capacity analysis show that the goals of parts produced can be reached for both planned capacities but also that there are potential constraints that have been identified in the system. The results of the leadership study also show that the overall approach should be slightly adapted to be better suited for the Chinese culture. The comparison of the two simulation software suggests that FACTS Analyzer is suit-able to use when less complex logic or systems are represented, however when building more complex models consisting of more complex logic Plant Simulation is more suitable.
2

Contributions to the Improvement of Multiuser PLC Home Networks

Achaichia, Pierre 12 October 2012 (has links) (PDF)
During the past few years, Power Line Communications (PLC) have become a popular connectivity solution to answer the growing need of home networks for bandwidth. As wireless technologies, this solution spares the user from cabling its Local Area Network (LAN), by directly using the home power grid as a transmission medium. While PLC generally offer a larger coverage than Wireless Local Area Networks (WLAN), the capacity offered by current systems is not sufficient to simultaneously support bandwidth intensive streams. In this thesis, we aim at exploring various solutions for future PLC networks. Firstly, we aim at improving the spectral efficiency of the current systems' Physical (PHY) layer, where two modulation schemes are compared. On the one hand, we study the modulation deployed in current PLC networks, called windowed Orthogonal requency Division Multiplexing (OFDM), and we highlight the main limitation of this solution in the particular context of PLC. On the other hand, we show that and alternative solution, called OFDM/Offset Quadrature Amplitude Modulation (OQAM), offers some degrees of freedom which could highly benefit to PLC networks. Secondly, the study is oriented toward the Media Access Control (MAC) layer of PLC systems, considering a multiuser utilization of the network. In this second part, we aim at proposing allocation solutions that will allow a more efficient utilization of the limited and shared transmission resource. We firstly study the opportunity of defining an Orthogonal Frequency-Division Multiple Access (OFDMA) transmission scheme for point-to-multipoint transmissions, in order to increase data rates by taking advantage of the diversity between users' channels. Finally, the last Chapter is dedicated to the study of broadcast and multicast communications in PLC networks, where we show that a smart aggregation of the set of users to reach could greatly improve efficiency of multicast transmissions.
3

Contributions to the Improvement of Multiuser PLC Home Networks / Contributions à l’amélioration des réseaux CPL domestiques multi-usagers

Achaichia, Pierre 12 October 2012 (has links)
Ces dernières années, la technologie des courants porteurs en ligne (CPL) a fait son apparition dans les réseaux domestiques afin de répondre au besoin grandissant de bande passante. Comme pour les solutions sans-fil, cette technologie présente l’avantage de ne pas nécessiter le déploiement de nouveaux câbles à l’intérieur de la maison, en utilisant directement le réseau électrique comme milieu de transmission. Offrant une zone de couverture plus importante que les réseaux Wi-Fi, les débits offerts par les équipements actuels ne sont néanmoins pas suffisants pour supporter simultanément des applications gourmandes en bande passante. Cette thèse vise donc à explorer différentes solutions pour les futurs réseaux domestiques basés sur cette technologie. L’étude a d’abord été menée au niveau de la couche Physique des systèmes, où deux solutions de transmission ont été comparées. D’un côté, la modulation windowed OFDM, déployée dans la grande majorité des réseaux actuels, est étudiée afin de mettre en avant ses limites dans le contexte particulier des réseaux sur courant porteur. Dans cette partie, nous montrons concrètement le gain en capacité que pourrait apporter une modulation alternative, l’OFDM/OQAM, présentant des degrés de liberté supplémentaires vis-à-vis de l’OFDM classique, et dont l’exploitation s’avère particulièrement intéressante pour cette étude. Dans un second temps, la problématique de la couche MAC a été abordée dans le contexte d’une utilisation multi-usager du réseau. L’objectif de cette seconde partie a été de proposer des solutions nouvelles pour l’allocation et le partage de la ressource entre les différents utilisateurs du réseau. Premièrement, nous étudions la possibilité de définir un nouveau mode d’accès, basé sur l’OFDMA, permettant de tirer efficacement parti de la diversité entre différents canaux de transmission, afin d’augmenter significativement les débits pour les transmissions point-à- multipoint. Enfin, le dernier chapitre aborde le problème de la transmission multicast inhérent aux réseaux PLC actuels, en proposant une méthode d’agrégation des utilisateurs résultant en une augmentation significative des débits. / During the past few years, Power Line Communications (PLC) have become a popular connectivity solution to answer the growing need of home networks for bandwidth. As wireless technologies, this solution spares the user from cabling its Local Area Network (LAN), by directly using the home power grid as a transmission medium. While PLC generally offer a larger coverage than Wireless Local Area Networks (WLAN), the capacity offered by current systems is not sufficient to simultaneously support bandwidth intensive streams. In this thesis, we aim at exploring various solutions for future PLC networks. Firstly, we aim at improving the spectral efficiency of the current systems’ Physical (PHY) layer, where two modulation schemes are compared. On the one hand, we study the modulation deployed in current PLC networks, called windowed Orthogonal requency Division Multiplexing (OFDM), and we highlight the main limitation of this solution in the particular context of PLC. On the other hand, we show that and alternative solution, called OFDM/Offset Quadrature Amplitude Modulation (OQAM), offers some degrees of freedom which could highly benefit to PLC networks. Secondly, the study is oriented toward the Media Access Control (MAC) layer of PLC systems, considering a multiuser utilization of the network. In this second part, we aim at proposing allocation solutions that will allow a more efficient utilization of the limited and shared transmission resource. We firstly study the opportunity of defining an Orthogonal Frequency-Division Multiple Access (OFDMA) transmission scheme for point-to-multipoint transmissions, in order to increase data rates by taking advantage of the diversity between users’ channels. Finally, the last Chapter is dedicated to the study of broadcast and multicast communications in PLC networks, where we show that a smart aggregation of the set of users to reach could greatly improve efficiency of multicast transmissions.

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