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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

Véhicule électrique et forme urbaine : une évaluation prospective / Electric vehicle and urban form : a prospective assessment

Solignac, Manon 17 January 2018 (has links)
Cette thèse s'intéresse à l'évaluation du potentiel et du coût du véhicule électrique comme solution pour réduire les émissions de CO$_2$ dues au transport de passagers en ville. Elle montre comment intégrer les habitudes de déplacement des usagers dans les méthodologies de quantification modifie ces évaluations. Les analyses portant sur le véhicule électrique calculent généralement un potentiel de réduction d'émissions et un coût sans distinguer les spécificités locales des territoires où ce véhicule pourra être mis en place et de l'utilisation qui en découle. Elles ne tiennent pas compte non plus des autres politiques existantes sur ce territoire, notamment de celles jouant sur la structure de la mobilité, à savoir son volume total et son partage modal. Ainsi, les différentes solutions de réduction d'émission de CO$_2$, technologiques d'un côté et portant sur la structure de la mobilité de l'autre, sont le plus souvent discutées de manière indépendante, et les possibles rétroactions de l'une vers l'autre sont peu analysées. Cette thèse vise donc à considérer conjointement l'introduction d'une solution technologique telle que le véhicule électrique et les structures urbaines dans lesquelles elle se déploie. Pour cela, nous développons un modèle de choix de technologies de véhicules des ménages, et l'intégrons à un modèle d'économie urbaine. Nous nous intéressons dans un premier temps, aux caractéristiques spatiales de la ville et donc à l'usage qui est fait de ce véhicule ; puis, dans un deuxième temps, à la mise en œuvre simultanée d'une solution jouant sur la structure de la mobilité pour réduire les émissions : la ceinture verte. Ces deux analyses nous permettent de mettre en évidence, et de quantifier, l'interdépendance d'une action s'appuyant sur la technologie et d'une autre s'appuyant sur la structure de la mobilité. Enfin, dans un troisième temps, nous introduisons l'hétérogénéité des usages ainsi que l'incertitude sur les prix futurs de l'énergie et les coûts futurs des batteries dans un modèle de calcul de la valeur d'option du déploiement du véhicule électrique. Nous montrons que ces deux éléments conduisent à réviser l'évaluation de la valeur d'option à la hausse / This thesis brings precisions on the measure of the emissions reduction potential in cities and the cost of electric vehicle by taking into account users driving patterns. Studies on electric vehicles or other solutions belonging to the "technological lever" compute emissions reduction potential and cost without discerning the local specificities of the areas where it would be used and the use that would be done of these vehicles. These studies don't take into account the other policies implemented in the area, including the ones that operate on a different lever such as the "mobility structure lever" : volume of activity and modal shares. Policies for reducing CO$_2$ emissions are often discussed independently and ignore the possible retroactions. To improve the evaluation of the potential of the electric vehicle, it seems essential to take into account the environment in which it would be developed. We use a urban economics model to first look at the spatial features of the city, and so at the use of this vehicle. Then we compute the impacts of the simultaneous introduction of the electric vehicle and a solution belonging to the "mobility structure lever" : the greenbelt. These two last points allow us to highlight the interdependency of the two action levers : technology and mobility structure. Then we take into account the use of the car by the households and the uncertainty around electric vehicle introduction, to improve the evaluation of the cost of this solution
2

En andra chans med Implanterbar Defibrillator : Upplevelser av förändrad livssituation / A second chance with Implantable Cardioverter Defibrillator : Perceptions of changes in life

Backe, Christina, Persson, Jennie, Pärna, Helena January 2014 (has links)
Varje år drabbas 10 000 människor av plötsligt hjärtstopp utanför sjukhus. De personer som överlever ett hjärtstopp kan bli aktuella för behandling med en Implanterbar Defibrillator (ICD).  Denna har funnits i bruk sedan 1980. Antalet implantationer ökar och utvecklingen går ständigt framåt. Sjukvården har en viktig roll i att stödja, utbilda och informera patienter och deras anhöriga så att de kan anpassa sig till det nya livet som ICD bärare. Syftet var att belysa ICD-bärares upplevelser av förändrad livssituation. Detta gjordes genom en litteraturstudie. Resultatet bygger på analys av åtta kvalitativa och tio kvantitativa vetenskapliga artiklar. Patienter med ICD upplever psykisk påfrestning, ett beroende av andra människor, att tvingas till levnadsförändringar samt acceptens till det nya livet som ICD-bärare. Implantation av en ICD innebär för många människor att få en ny chans till livet men det innebär också fysiska, psykiska och sociala omställningar i det vardagliga livet. Dessa omställningar påverkar också nära anhöriga. Eftersom antalet ICD implantationer ständigt ökar och det har visat sig att livssituationen på olika sätt förändras är det viktigt att omvårdnaden av denna patientgrupp präglas av individuellt stöd och utbildning i kombination av gott tekniskt kunnande för att underlätta anpassningen till livet som ICD-bärare. / Every year, there are 10 000 cases of sudden cardiac arrest outside of hospitals. Those who survive a cardiac arrest may be considered for treatment with an Implantable Cardioverter Defibrillator (ICD). The ICD has been in use since 1980 and the developments along with the number of implantations are continuously evolving. The health care system has an important role in supporting, educating and informing the patients and their families, to help them adapt to the new life as or with an ICD-bearer. The purpose of this study is to highlight the experiences and life alterations the ICD-bearer faces. The results are based on the analysis of eight qualitative and ten quantitative research articles. Patients with ICDs experience psychological distress; a dependence on other people; being forced to make life alterations and finding acceptance for the new life as an ICD-bearer. For many, an ICD is equivalent to a new chance at life, but it also represents every day physical, psychological and social changes. Changes that also affect close relatives. The care of these patients ought to be characterized by individual support and education, as the number of ICD implantations is constantly increasing and since it has been proven that life situations change. This in combination with good technical expertise facilitates the adaptation to life as an ICD-bearer.
3

Spectrum usage models for the analysis, design and simulation of cognitive radio networks

López Benítez, Miguel 20 July 2011 (has links)
The owned spectrum allocation policy, in use since the early days of modern radio communications, has been proven to effectively control interference among radio communication systems. However, the overwhelming proliferation of new operators, innovative services and wireless technologies during the last years has resulted, under this static regulatory regime, in the depletion of spectrum bands with commercially attractive radio propagation characteristics. An important number of spectrum measurements, however, have shown that spectrum is mostly underutilized, thus indicating that the virtual spectrum scarcity problem actually results from static and inflexible spectrum management policies rather than the physical scarcity of radio resources. This situation has motivated the emergence of Dynamic Spectrum Access (DSA) methods based on the Cognitive Radio (CR) paradigm, which has gained popularity as a promising solution to conciliate the existing conflicts between spectrum demand growth and spectrum underutilization. The basic underlying idea of DSA/CR is to allow unlicensed (secondary) users to access in an opportunistic and non-interfering manner some licensed bands temporarily unoccupied by the licensed (primary) users. Due to the opportunistic nature of this principle, the behavior and performance of a DSA/CR network depends on the spectrum occupancy patterns of the primary system. A realistic and accurate modeling of such patterns becomes therefore essential and extremely useful in the domain of DSA/CR research. The potential applicability of spectrum usage models ranges from analytical studies to the design and dimensioning of secondary networks as well as the development of innovative simulation tools and more efficient DSA/CR techniques. Spectrum occupancy modeling in the context of DSA/CR constitutes a rather unexplored research area. This dissertation addresses the problem of modeling spectrum usage in the context of DSA/CR by contributing a comprehensive and holistic set of realistic models capable to accurately capture and reproduce the statistical properties of spectrum usage in real radio communication systems in the time, frequency and space dimensions. The first part of this dissertation addresses the development of a unified methodological framework for spectrum measurements in the context of DSA/CR and presents the results of an extensive spectrum measurement campaign performed over a wide variety of locations and scenarios in the metropolitan area of Barcelona, Spain, to identify potential bands of interest for future DSA/CR deployments. To the best of the author's knowledge, this is the first study of these characteristics performed under the scope of the Spanish spectrum regulation and one of the earliest studies in Europe. The second part deals with various specific aspects related to the processing of measurements to extract spectrum occupancy patterns, which is largely similar to the problem of spectrum sensing in DSA/CR. The performance of energy detection, the most widely employed spectrum sensing technique in DSA/CR, is first assessed empirically. The outcome of this study motivates the development of a more accurate theoretical-empirical performance model as well as an improved energy detection scheme capable to outperform the conventional method while preserving a similar level of complexity, computational cost and application. The findings of these studies are finally applied in the third part of the dissertation to the development of innovative spectrum usage models for the time (in discrete- and continuous-time versions), frequency and space domains. The proposed models can been combined and integrated into a unified modeling approach where the time, frequency and space dimensions of spectrum usage can simultaneously be reproduced, thus providing a complete and holistic characterization of spectrum usage in real systems for the analysis, design and simulation of the future DSA/CR networks.

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