Dissertations / Theses on the topic 'LXS Ltd'
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Ekström, Angela, and Åsa Gustavsson. "LTG- metodens betydelse." Thesis, Malmö högskola, Lärarutbildningen (LUT), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-27661.
Full textAbstractThe importance of LTG- method- Six teachers´ views on their work with reading- and writing development skills in school year 1, from an LTG-perspectiveAngela Ekström and Åsa GustavssonWe have done a survey were our datacollection has been made through interviews. We wanted to know six teachers´ views on their work with reading- and writing development skills in school year 1, from an LTG- perspective (reading on the ground of speaking). With this survey we want to accomplish development of knowledge for students who wants to become teachers. Our main purpose is to gain more knowledge and create a deeper understanding for how reading- and writing development works in real life in different ways, with focus on LTG. One of our conclusions is that it’s not a question of choosing a method, instead it’s all about teachers attitudes and their believes in their work with reading- and writing development.
Holmberg, Mattias, and Stefan Hen. "LTA kontra självfall : Ett långsiktigt perspektiv." Thesis, KTH, Byggteknik och design, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-127665.
Full textThe purpose of this report is to make a comparison between the two currently used sewage solutions, PSS (Pressure Sewage System) and the more conventional gravity based sewage-system during a vast period of time. Aspects such as investment, maintenance, upkeep, environmental, technology and terrain have been analyzed. The research has resulted in this report and an Excel-program which calculates an estimated economical difference between the two solutions, in a specific case chosen by the user, to determine which is more economically beneficial. This program, used hand in hand with the report, is suppose to increase the knowledgebase regarding the subject of sewage solutions among officials working with these kinds of matters in Sweden.
Kukacka, Leos. "Qualité de l'énergie dans les alimentations électriques : applications dans les réseaux d'éclairage." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30011/document.
Full textThis dissertation thesis is concerned with temporal fluctuations of the luminous flux of LED lamps, a phenomenon referred to as flicker. Flicker is usually regarded as a disturbance due to its negative impact on human health. For lighting systems based on light emitting diodes (LED), its definition has recently been formalised in norm IEEE 1789-2015 and has been documented on devices supplied with AC voltage. AC flicker results from interactions between network impedance, voltage and current harmonics, and the AC to DC converter. DC supplies are generally obtained by switching converters. Consequently, the same perturbing factors are present on DC networks. The thesis summarises the differences between the characteristic properties of flicker under AC and DC supplies. It has been shown in the literature and also in this thesis that the key factor affecting flicker with LEDs is the design of the LED driver-a necessary part of the LED lighting systems. This thesis describes a methodology for the evaluation of the flicker sensitivity of DC supplied LED lamps and analyses how the sensitivity changes when the LED drivers are simplified and accustomed to DC supply. The thesis presents a set of measurement experiments aimed to determine the typical flicker response of LED lamps both under AC and DC supply. Further experiments were performed to reveal the impact of accustomising the driver to the DC supply (removing the diode rectifier). It was found that some lamps show better flicker immunity while other lamps show worse flicker immunity. These experiments are accompanied by LED driver simulations aiming to reproduce and explain the measurement results. The thesis further describes a measurement experiment aimed to show the typical severity of the voltage fluctuation in a low voltage DC network coupled to AC mains and its impact on the flicker. It is concluded that such a system is robust enough to filter out any perturbations coming from the AC supply, but an undesired interaction between the lamp and the supply may occur
López, Muñoz Nicolás Antonio. "Efecto de las Redes de Cuarta Generación (LTE) en los Servicios Móviles en Chile." Tesis, Universidad de Chile, 2011. http://www.repositorio.uchile.cl/handle/2250/104136.
Full textJoseph, Arun Antony. "Defect-based testing of LTS digital circuits." Enschede : University of Twente [Host], 2006. http://doc.utwente.nl/57765.
Full textMöller, Mollie, and Jenny Johansson. "LTG-metoden ur ett KME-pedagogiskt perspektiv med en inkluderande infallsvinkel." Thesis, Malmö högskola, Lärarutbildningen (LUT), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-34774.
Full textFröberg, Carolina. "LTG-metod och genrepedagogik för andraspråksinlärning." Thesis, Högskolan Dalarna, Pedagogiskt arbete, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:du-21055.
Full textEngfelt, Marie, and Marie Johansson. "Läsning - Utveckling och uppföljning." Thesis, Malmö högskola, Lärarutbildningen (LUT), 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-27886.
Full textThis essay is about different kind of models you are using when you teach children how to read. The essay also talks about LUS, a schedule that shows where the child is in his readinprogress.
Ben, Rekhissa Hajer. "Réduction de la consommation énergétique dans les modules M2M utilisant la technologie LTE/LTE-A." Thesis, Université Côte d'Azur (ComUE), 2019. http://www.theses.fr/2019AZUR4085.
Full textMachine-to-Machine (M2M) communication, which refers to the interaction between intelligent devices without human intervention, is gaining more prominence in mobile cellular networks. Long Term Evolution (LTE) and LTE-Advanced (LTE-A) networks are considered excellent candidates to support M2M communication. However, M2M communication over LTE/LTE-A networks faces some challenges. The main challenge is how to reduce energy consumption for M2M devices, as the majority of them are battery driven. The aim of this thesis is to propose solutions to reduce energy consumption in M2M devices over LTE/LTE-A technologies. We proposed two approaches; the first one consists of increasing time spent in low power mode by buffering data until reaching given thresholds of number of buffered data and maximum delay authorized. This approach allows to reduce signaling from idle state to connected state. Besides, it considers quality of service (QoS) requirements. The second approach consists of proposing two uplink schedulers which take into account the coexistence of M2M and Human-to-Human (H2H) devices. Both of them consider channel quality while allocating resource blocks, which have a consequence reducing energy consumption in M2M devices. Our second algorithm consider, also, delay constraint
Tall, Abdoulaye. "Optimisation et Auto-Optimisation dans les réseaux LTE." Thesis, Avignon, 2015. http://www.theses.fr/2015AVIG0208/document.
Full textThe mobile network of Orange in France comprises more than 100 000 2G, 3G and 4G antennas with severalfrequency bands, not to mention many femto-cells for deep-indoor coverage. These numbers will continue toincrease in order to address the customers’ exponentially increasing need for mobile data. This is an illustrationof the challenge faced by the mobile operators for operating such a complex network with low OperationalExpenditures (OPEX) in order to stay competitive. This thesis is about leveraging the Self-Organizing Network(SON) concept to reduce this complexity by automating repetitive or complex tasks. We specifically proposeautomatic optimization algorithms for scenarios related to network densification using either small cells orActive Antenna Systems (AASs) used for Vertical Sectorization (VeSn), Virtual Sectorization (ViSn) and multilevelbeamforming. Problems such as load balancing with limited-capacity backhaul and interference coordination eitherin time-domain (eICIC) or in frequency-domain are tackled. We also propose optimal activation algorithms forVeSn and ViSn when their activation is not always beneficial. We make use of results from stochastic approximationand convex optimization for the mathematical formulation of the problems and their solutions. We also proposea generic methodology for the coordination of multiple SON algorithms running in parallel using results fromconcave game theory and Linear Matrix Inequality (LMI)-constrained optimization
Jalier, Camille. "Communication et contrôle dans les architectures homogènes de circuits pour télécommunications." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20033/document.
Full textThis PhD research aims to solve challenges about control and communication in the design of digital embedded systems for 4G telecom applications. The application complexity added to the increasing productivity gap force to think about new design methodologies and the underlying architectures. Several new research directions is proposed in this work. A methodology for design space exploration and a digital architecture based on homogeneous and flexible processing units interconnected by a Network-on-Chip is proposed. A processing unit is a cluster of DSPs controled by a MIPS processor to compute telecom applications. To meet low power constraints, we propose optimization techniques based on resource management including task migration
Hidalgo, Balderas Carlos Gabriel. "An��lisis de los efectos que producen las recesiones econ��micas en las PYMES de la ciudad de Puebla. Propuesta de implementaci��n de un programa para contrarrestar los efectos." Thesis, Universidad de las Am��ricas Puebla, 2012. http://catarina.udlap.mx/u_dl_a/tales/documentos/lad/hidalgo_b_cg/.
Full textHerrera, Polo Pablo C., Benito Juárez, and Universidad Peruana de Ciencias Aplicadas (UPC). "Perspectivas en los Laboratorios de Fabricación Digital en Latinoamérica." SIGraDi 2012, 2012. http://hdl.handle.net/10757/604776.
Full textTrinh, Le-Huy. "Antennes reconfigurables pour les applications mobiles et réseaux sans fil." Thesis, Nice, 2015. http://www.theses.fr/2015NICE4047/document.
Full textIn recent years, telecommunication technologies have enormous progress, especially cellular communications and wireless sensor networks. To meet the demand of increasing transmission capacity, improving quality of cellular communication channels, expanding the operating band of the equipment is necessary. As passive antenna has reached the limit on increasing the operating band with the small size, the use of frequency reconfigurable antenna is a feasible solution. Besides, in the applications of WSN, to reduce collisions, increase communication distance and optimize consumption, directional reconfigurable antenna is a good proposal. In this thesis we present several reconfigurable antenna structures. Firstly, a new component is introduced; digitally tunable capacitor (DTC). Thanks to its advantages, such parts are good candidate to be integrated in the antenna for cellular communication and wireless sensor network applications. After, several antennas are introduced include multiband antenna, MIMO and frequency reconfigurable antenna, which can be used to extend the operating frequency band of the communication system, optimize spectral efficiency and quality improve channel quality. The structures of these antennas are introduced together with the results of simulation and measurement for the purpose of solving the challenges given in the future cellular communications systems. And then, the proposed approach to the design of reconfigurable directional antennas is presented. Several reconfigurable directional antennas, which are used in applications of WSN, are introduced. Thanks to the use of directional antennas reconfigurable, performance of WSN system will be optimized
Gaudreau, Guy. "Les causes d'une participation à la grève: grévistes et non-grévistes de la Noranda Mines Ltd, juin 1934." AU Press, Athabasca University, 1999. https://zone.biblio.laurentian.ca/dspace/handle/10219/105.
Full textRagaleux, Alexandre. "Mécanismes d'accès multiple dans les réseaux sans fil large bande." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066407/document.
Full textIn this thesis, we study the resource allocation problem within the framework of 4G LTE networks. The OFDMA access method divides the radio resources both in the frequency and time domains. Due to channel impairments, users do not always have the same transmit/receive rates on each resource. In this context, our problem is to share the radio resources between users and enable them to transmit/receive data. The algorithm used to allocate resources is of fundamental importance on system performance. The LTE standard adds constraints to this problem and makes harder the exploitation of the frequency and the multi-user diversity. Indeed, under these constraints, we show that the resource allocation problem becomes part of the « most difficult » problems. Therefore, the conventional algorithms are often not adapted to a real LTE network. We provide resource allocation algorithms for both the uplink and downlink of LTE. The constraints of the standard are rigorously taken into account in order to build effective solutions. In addition, the proposed algorithms are generic and can adapt to a wide variety of objectives. In particular, we focus on the support of multimedia traffic with heterogeneous quality of service requirements (bit error rate, delay, jitter, etc.). Indeed, the gradual increase of the offered throughput and the strong popularity of smart mobile devices lead to a massive use of multimedia applications. Our algorithms are validated through extensive simulation. By this means, we show that the inclusion of LTE constraints is essential to achieving high performance
Perillat-Merceroz, Guillaume. "Mécanismes de croissance et défauts cristallins dans les structures à nanofils de ZnO pour les LED." Thesis, Grenoble, 2011. http://www.theses.fr/2011GRENI053/document.
Full textQuantum well ZnO nanowires and p-type doping by nitrogen ion implantation are studied to make ultraviolet light-emitting diodes. O-polar pyramids and Zn-polar nanowires on sapphire and ZnO substrates are grown. Organized growth of nanowires on a masked Zn-polar ZnO is demonstrated. Similarly, GaN pyramids and nanowires are grown on Ga and N-polar GaN respectively. On sapphire, the dislocation elimination in the underlying pyramids is analyzed. Nanowires with no structural defects allow the growth of ZnO / Zn (1-x) Mg x O core-shell quantum wells. Plastic relaxation is studied, and the Mg composition is optimized to avoid it and attain an internal quantum efficiency as high as 54%. Concerning ion implantation, the defects are identified before and after annealing. They disappear in the near-surface, which lead to an easier recovery of nanowires compared to bulk ZnO. However, a recovered material with activated acceptors is not obtained
Tartakowsky, López Ingrid. "Psicoterapia asistida con LSD, Psilocibina y MDMA. Descripciones realizadas por los terapeutas en torno a los procesos clínicos." Tesis, Universidad de Chile, 2014. http://repositorio.uchile.cl/handle/2250/135079.
Full textEn la presente investigación cualitativa se describen las psicoterapias asistidas con LSD, psilocibina y MDMA, a partir de entrevistas realizadas a algunos terapeutas que las llevan a cabo con sus pacientes. Para ello se ha indagado en ciertos aspectos que articulan la clínica, tales como sus fases, sus objetivos, la cura, el terapeuta, el vínculo entre paciente y terapeuta, el lugar de trabajo y las técnicas que se utilizan; entre las que se encuentran los usos de sustancias psicoactivas. Utilizando una metodología de análisis de contenido, se han observado diversos tipos de psicoterapias asistidas con fármacos, así como algunas de las dimensiones que las atraviesan: política, real y corporal. También se ha realizado una clasificación de los efectos catalizadores que comparten la LSD, la psilocibina y la MDMA, y que pueden ser de interés para ser utilizados en psicoterapia. Además, destaca el cuerpo como una dimensión en la que convergen: la emergencia de las problemáticas del sujeto, con los efectos potenciadores de las drogas y las formas de intervención del terapeuta. Así mismo resaltan ciertos elementos del lugar de trabajo como vehiculizadores de las experiencias que acontecen con dichas sustancias, como son el elemento sonoro y el espacio exterior, los que bajo un cierto ordenamiento encausan al sujeto hacia lo terapéutico. También se han realizado algunas reflexiones y vínculos entre los postulados de Sigmund Freud y Stanislav Grof respecto de los estados de conciencia y su emergencia en el campo psicoterapéutico. Además, se han encontrado diversas convergencias y divergencias entre el marco analítico y el de terapias asistidas que se realiza hoy en día. Asimismo han aparecido cuatro aspectos que son propios de la clínica y que permiten diferenciar las experiencias terapéuticas de las recreacionales que se pueden llegar a tener con LSD, psilocibina y MDMA. Estas consideraciones permiten concluir que es en la relación que establece un sujeto con su estado modificado de conciencia donde residen las posibilidades terapéuticas, y no tanto en los efectos directos de la sustancia que se ingiere. Del mismo modo, lo encontrado en este estudio muestra de qué maneras las terapias asistidas han evolucionado tomando los planteamientos freudianos hasta emerger de la forma que las caracteriza en la actualidad
Thin, Guillaume. "Recherche de solutions optimales pour les LED et OLED utilisées en environnement automobile." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLV005.
Full textThe large introduction of optoelectronics technologies in automotive applications is related to the high performances offered by LEDs. Indeed, these new light sources allow cutting down the electrical consumption and ensuring long lasting of lighting functions. Besides, their reduced size and their electronics behavior enable new styling and operating functions. Yet, reliability remains a great concern in automotive applications.We identify in this manuscript the real reliability stakes and emphasize the highest importance of robustness versus lifetime of LED for automotive applications. We then describe the methods and tools necessary to characterize the thermal, electrical and optical parameters of these components. In particular we propose a new method for junction temperature estimation. Characterizations results for LEDs used in pulsed applications are given and solutions are proposed to improve their robustness and performances under such conditions. Moreover, the development of a test bench is presented and results obtained are discussed. Finally, we propose a methodology of characterization and evaluation of the reliability of OLED used in automotive applications
Carlsson, Elisabeth. "Tre läsinlärningsmetoder : en studie om läsinlärningen i år 1." Thesis, Linköping University, Department of Educational Science (IUV), 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1515.
Full textSyftet med denna studie har varit att dels få en teoretisk kunskap om tre olika läsinlärningsmetoder. Jag var medveten om att Den traditionella läsinlärningsmetoden och LTG tillämpas flitigt i den svenska skolans undervisning och ville därför skaffa mig kunskap om dessa två metoders metodik. Wittingmetoden hade jag endast hört talas om och blev därför intresserad av att ta reda på mer om den.
I den empiriska delen av studien har jag intervjuat tre verksamma lärare som har erfarenhet av att arbeta med läsinlärningen i år 1. Intervjufrågorna belyser framförallt hur lärarna metodiskt arbetar med läsinlärningen.
Resultatet visar att samtliga lärare inteenbart arbetar utifrån en metod, utan väljer att blanda. Genom detta resultat framgår det tydligt att barnen lär sig oavsett vilken metod man använder sig av.
I slutdiskussionen belyser jag skillnader och likheter mellan lärarnas arbetssätt och anknyter det till de olika läsinlärningsmetoderna.
Tabia, Nourredine. "Modèles et algorithmes pour l'optimisation robuste dans les Self-Organizing Network (SON) des réseaux mobiles 4G (LTE)." Phd thesis, Université de Technologie de Belfort-Montbeliard, 2013. http://tel.archives-ouvertes.fr/tel-00983358.
Full textMaaz, Bilal. "Allocation des ressources radio dans les réseaux sans fil de la 5 G." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLV010/document.
Full textMobile communication is considered as one of the building blocks of smart cities, where citizens should be able to benefit from telecommunications services, wherever they are, whenever they want, and in a secure and non-costly way. This can be done by dense deployment of the latest generation of mobile broadband networks. However, this dense deployment will lead to higher energy consumption, and thus more gas emission and pollution. Therefore, it is crucial from environmental point of view to propose solution reducing energy consumption. In this thesis, we introduce dynamic resource management methods that increase throughput and energy efficiency, and thus reduce pollution. In this framework, we are targeting green multi-cell networks where increased energy efficiency must take into account the increased demand of data by mobile users. This increase, which is exponential in terms of throughput, pushed operators to use the entire frequency spectrum in all cells of the latest generation of mobile networks. As a result, Inter-Cellular Interference (ICI) became preponderant and degraded the performance of users, particularly those with poor radio conditions. In this thesis, we focus on the techniques of power control on the downlink direction, which is considered as one of the key methods of Inter-Cell Interference Coordination (ICIC) while focusing on energy efficient methods. We propose centralized and decentralized methods for this problem of power allocation: centralized methods through convex optimization, and decentralized methods based on non-cooperative game theory. Furthermore, we propose a power control heuristic which has the advantage of being stable and based on signaling messages already existing in the system. The power control problem has a relevant impact on the allocation of radio resources and on the association of mobile users with their servicing Base Station. Therefore, in the second part of the thesis, we formulated a global problem encompassing power control, radio resources allocation, and control of users’ association to a base station. These three sub-problems are treated iteratively until the convergence to the overall solution. In particular, we propose three algorithms for the user association problem: a centralized algorithm, a semi-distributed algorithm and finally a fully distributed algorithm based on reinforcement learning. In addition, for power allocation we implement centralized solutions and distributed solutions. The proof of convergence for the various algorithms is established and the in-depth simulations allow us to evaluate and compare quantitatively the performance, the energy efficiency, and the convergence time of the proposed algorithms
Taylor, Jack Rodney. "Tactile sensing : a case study of the Lord Corporation LTS-300T." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/19013.
Full textEscobar, Vílchez Mario Raúl. "Bimex Servicios Ltda. : Servicio Técnico para los equipos S&C." Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/147782.
Full textAutor autoriza el acceso a texto completo de su documento a partir de agosto del 2023.
El mercado eléctrico en Chile, es un mercado representado por las empresas generadoras, distribuidoras, transmisoras de electricidad y empresas mineras que tienen sus propios sistemas eléctricos. Estos sistemas son de media y alta tensión (de 1 a 60 y de 60 a 220 kilovoltios respectivamente según la SEC de Chile1). Los proveedores principales de este mercado son empresas o marcas multinacionales que fabrican estos equipos en el exterior. Estos proveedores principales son Schneider, ABB, Siemens e Eaton, que son marcas provenientes de Estados Unidos y Alemania, que fabrican equipos eléctricos clasificados como; interruptores, seccionadores y reconectadores.2 En la actualidad estos son equipos de protección eléctrica que se han ido modernizando al igual que la industria de la computación, y se han convertido en equipos automatizados que están interconectados entre sí, que conforman una red de distribución inteligente que pueden ser operados y monitoreados a kilómetros de distancia a través de wifi o sistema de radio, con el fin de mejorar los tiempos de reposición cuando se presenten cortes de energía. Sin embargo, estos sistemas aún no se han implementado bien Chile, porque vienen con tecnologías avanzadas de los países mencionados y con sus respectivas normas de electricidad, seguridad y manera de operar que no necesariamente cumplen con la norma chilena, mayormente tienen que pasar un proceso de adaptación que tienen que ser desarrollados por postventa de estas marcas. Ejemplo el sector minero es un mercado muy exigente que sobrepone sus normas y maneras de operar, donde cualquier equipo tiene que ser adaptados a sus requerimientos y a su medida y que se pueda operar como ellos acostumbran, pero sin dejar de ser equipos inteligentes, por consiguiente, hay que desarrollar soluciones integrales, mantención preventiva y correctivo sin perder la garantía. Por otro lado, normalmente los clientes contratan a talleres multimarcas y en su defecto tienen sus propios talleres de mantención que ponen en riesgo la garantía de los equipos por no ser los especialistas. Este plan se trata de crear una empresa de Servicio Técnico llamada Bimex Servicios Ltda., con una estrategia de diferenciación enfocada en calidad, tiempo oportuno y garantía de fábrica que realice los servicios de mantenimiento preventivo y correctivo a los equipos S&C Electric Company, la cual es una marca estadounidense de equipos eléctricos en media y alta tensión representada en Chile por la UNE de Ventas (Comercializadora Bimex Ltda.) El modelo se basa en crear dos divisiones; una de servicio de postventa para el mantenimiento preventivo y la otra es el soporte técnico para solucionar las urgencias del mantenimiento correctivo en el menor tiempo posible. La misión de Bimex Servicios Ltda., es brindar un servicio técnico capaz de hacer que los clientes deleguen la función y preocupaciones de sus equipos antiguos S&C adquirido y que están fuera de garantía y a los equipos nuevos para que no la pierdan, que mejor que delegar a los únicos especialistas certificados en Chile como será Bimex Servicios Ltda. Los aspectos financieros son indispensables como el análisis del sector industrial y las potencialidades del proyecto dentro de su análisis de viabilidad evaluado a 5 años, obteniendo un valor actual neto positivo de CLP 142.900.494, asociado a una tasa interna de retorno de 54,23%, un retorno sobre la inversión de 62% y con un estimado de recuperación de la inversión de 3 años.
Eliasson, Carolina. "Pedagogens arbete med läs- och skrivinlärning." Thesis, Malmö högskola, Fakulteten för lärande och samhälle (LS), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-34927.
Full textGao, Xue. "Injection de spin dans les semiconducteurs et les matériaux organiques." Thesis, Université de Lorraine, 2019. http://www.theses.fr/2019LORR0059/document.
Full textSpintronics with semiconductors is very attractive as it can combine the potential of semiconductors with the potential of the magnetic materials. GaN has a long spin relaxation time, which could be of potential interest for spintronics applications. Organic spintronics is also very appealing because of the long spin lifetime of charge carriers in addition to their relatively low cost, flexibility, and chemical diversity. In this thesis, we investigate spin injection in spin LEDs containing either InAs/GaAs quantum dots or InGaN/GaN quantum wells. Moreover, we further study spin polarized transport in organic multiferroic tunnel junctions (OMFTJs). Firstly, we will show that the circular polarization of the light emitted by a LED containing a single layer of p-doped InAs/GaAs quantum dots (QDs) can reach about 18% under zero applied magnetic field. A clear correlation is established between the polarization degree of the emitted light and the perpendicular magnetization of the injector layer. The polarization reaches a maximum for an applied bias of 2.5V at 10K, which corresponds to an injected current of 6 µA. Also, we report a remarkable behavior of the polarization in the temperature region 60-80K. The interpretation of the bias and temperature dependence of the polarization is discussed in light of the competition between radiative recombination time τr and the spin relaxation time τs. In addition, significant efforts have been devoted to developing a perpendicular spin injector on GaN based materials to achieve spin injection without applying a magnetic field. Firstly, the growth of MgO has been investigated at various growth temperatures. Then, we studied the growth of either Fe or Co on MgO/GaN. In contrast to Fe/MgO, the Co/MgO spin injector yields a clear perpendicular magnetic anisotropy. In addition, ab-initio calculations have been performed to understand the origin of the perpendicular magnetic anisotropy at the Co/MgO(111) interface. Finally, we investigate multiferroic tunnel junctions (MFTJs) based on organic PVDF barriers doped with Fe3O4 nano particles. The organic MFTJs have recently attracted much attention since they can combine advantages of spintronics, organic and ferroelectric electronics. We report on the successful fabrication of La0.6Sr0.4MnO3/PVDF:Fe3O4/Co OMFTJ, where the poly(vinylidene fluoride) (PVDF) organic barrier has been doped with ferromagnetic Fe3O4 nanoparticles. By changing the polarization of the ferroelectric PVDF, the tunneling process in OMFTJ can be switched either through the LSMO/PVDF/Co part (positive polarization) or through the Fe3O4/PVDF/Co part (negative polarization). This corresponds to a reversal of tunneling magnetoresistance (TMR) from +10% to -50%, respectively. Our study shows that the doping of OMFTJs with magnetic nanoparticles can create new functionalities of organic spintronic devices by the interplay of nanoparticle magnetism with the ferroelectricity of the organic barrier
Zaaraoui, Hind. "Gestion de ressources bout-en-bout et contrôle de la qualité de service en mobilité dans les réseaux LTE/LTE-Advanced." Thesis, Avignon, 2017. http://www.theses.fr/2017AVIG0220/document.
Full textThe technology evolution of Radio Access Network (RAN) in the context of 5th Generation (5G) is not only guided by improving the network performance but also by the need to transform all the technologies into intelligent dynamic ones. The new 5G is a flexible technology that will be able to satisfy at the same time each user of any type of mobility (static or mobile) or service request (real and non-real time service) without modifying any models or algorithms in networks. All physical use cases will be able to be considered by the network intelligently and resource managed automatically. The objective of this thesis is to analyse and enhance radio performance taking into account vehicular mobility by managing dynamically and intelligently the available resources. To this end, we describe different users mobility models for discrete and continuous modeling. The discrete model using the well-known car following model is well adapted for simulations. The continuous one is useful to derive analytical key performance indicators (KPI). The novelty of the thesis is the analytical formulation of KPIs that take into account the physical mobility in the radio traffic which is not necessary stationary. As an example, the impact of a traffic light on performance indicators in a cell is investigated. It is shown that a periodical physical traffic congestion due to the traffic light deteriorate periodically the cell performance. A first given solution is to improve resource allocation and control in the context of LTE-Advanced heterogeneous network. A small cell is deployed near the traffic light to relieve periodic congestion and QoS degradation. Three resource allocation and control schemes are investigated: a full frequency reuse, a static and a dynamic frequency splitting algorithm that are optimized with respect to a throughput based alpha-fair utility. For sake of financial and energy costs decreasing, another solution is provided using new antenna array technologies in order to manage efficiently heterogeneous, fixed and mobile traffic. A heterogeneous antenna system with different large antenna array technologies is considered to ooad static congestion areas and also the dynamical mobile congestion: Virtual Small Cell (VSC), virtual small cell with Self-Organizing Network (VSC-SON) and beamforming with multilevel global codebook that manages the heterogeneous antenna system at the Base Station (BS). The first two technologies improve the cell performance due to the capability to focus the signal at the traffic concentration. The novel beamforming solution with global codebook can further and significantly improve performance due to the capability to focus the signal along the road and to implicitly balance the traffic between the different antennas. We compare all these technologies and their impact on the network performance. The issue of user selection to allocate a portion (in time or in bandwidth) of the available resource is also analyzed. Moreover the context of resource management and network performance for 5G in high mobility is one of the future challenges. Thanks to the Minimization of Drive Testing (MDT) technology, networks can have Signal to Interference plus Noise Ratio (SINR) information with Geo-Localized Measurements (GLM).We introduce the concept of Forecast Scheduler for users in high mobility. It is assumed that a Radio Environment Map (REM) can provide interpolated SINR values along the user trajectories. Mobile users experience in their trajectories different mean SINR values. In mobile networks, schedulers exploit channel quality variation by giving the signal to the user experiencing best channel conditions while remaining fair. Nevertheless, we cannot record data rates of users with high mobility due to a very small time coherence. The Forecast Scheduling will exploit the SINR variation during users' trajectories
Perillat-merceroz, Guillaume. "Mécanismes de croissance et défauts cristallins dans les structures à nanofils de ZnO pour les LED." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00673255.
Full textLuong, Giap. "Conception d’un amplificateur de puissance reconfigurable en CMOS nanométrique pour les applications LTE dans les drones." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0122/document.
Full textUnmanned aerial vehicles (UAVs), often known as drones, have been finding numerous applications in life. Drones applications need several essential performance indicators such as coverage, signal strength, latency, and mobility under scenarios. Therefore, the use of wireless communications in drones is critical to address all requirements. Because of high-speed connections between drones and users to transfer high-resolution high-volume data, latest wireless generations, namely the LTE standard, are privileged. It is straightforward that the integration of RF blocks is essential to build a system-on-chip and shrink the size of drones. To answer the above question, this thesis aims to develop a fully integrated reconfigurable high-performance innovated PA that supports 4G LTE standard to be used in UAVs’ applications. The fully integrated 65-nm CMOS power amplifier (PA) provides a watt-level output power, addresses the linearity/efficiency trade-off. A four-winding transformer is implemented to configure the multi-mode operation of the PA. The “segmented bias” technique allows the PA to increase the linearity. The PA not only obtains high radiofrequency performances but also demonstrates a potential to adopt it design in the lower 5G band
Sadaoui, Lamia. "Conception de systèmes antennaires MIMO multi-standards LTE pour les nœuds relais." Thesis, Université Côte d'Azur (ComUE), 2018. http://www.theses.fr/2018AZUR4222/document.
Full textTo deploy the fourth generation called 4G/LTE or "LTE advanced", mobile operators face strong constraints: they must ensure a good geographic coverage but also an excellent quality of service. This requires new methods that go far beyond what has been implemented for GSM or 3G networks. The telecom industry has created the concept of "small cells" that reinforce the "macrocells" deployed by the operators. This thesis tries to provide a solution to this problem and more particularly through the development of antennas for a product called "smart cell". This study, supported by the FUI project NETCOM, should enable mobile operators to extend the coverage and capacity of their networks at a lower cost while maintaining a good quality of service. To do that, the aim of this thesis more particularly is the design of a multi-band multi-antennas MIMO system (Multiple-Input Multiple-Output) dedicated to relay nodes for the deployment of the fourth generation 4G/LTE or "LTE advanced". The antenna design considers the coverage of the three LTE operating frequency bands and must be compatible with them. The (700-900 MHz) frequency band is used for the LTE 700 and LTE 800 bands, (1710-1880 MHz) for the GSM 1800/LTE 1800 bands and the last (2500-2690 MHz) for the LTE 2600 bands. In our first study, a reference system with 4 access was studied in simulation and measured, for only the low band 700-900 MHz. In a second study, we tried to cover the other two higher bands to have a tri-band system using the parasitic elements to get a three-band MIMO system with 4 access. We studied then, the influence of the environment close to the antenna system, with the presence of a metallic radiator. As we often encounter a frequent problem in multi-antenna systems which is the coupling problem between the different access of a multi antenna system, so we have studied and realized a decoupling technique. This technique was used to enhance the isolation between the different access
Ster, Jeanne. "Rôles d'un facteur d'échange activé par l'AMPc, Epac, dans les neurones : activation d'un canal potassique sensible au calcium et induction d'une LTD." Montpellier 2, 2007. http://www.theses.fr/2007MON20022.
Full textKristiansson, Camilla. "Under parasollen : En komparativ studie utifrån whole language-teorin och LTG-metoden." Thesis, Karlstad University, Faculty of Arts and Education, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-1280.
Full textAbstract
The purpose of this study is to analyse the reading- and writing-approaches: the LTG-method and the whole language-theory. The attention is to perform a comparative literate-study to distinguish their similarities and differences, and examine which one of the approaches that is most clearly anchored in the syllabus of the subject Swedish. The starting-point of the study is the questions: Which similarities respectively differences have the LTG-method and the whole language-theory? Which one of these theories is most clearly anchored in the syllabus of the subject Swedish? The study has shown that both the whole language-theory and the LTG-method can anchor in the syllabus for Swedish. However the whole language-theory has stronger hold in the syllabus, as the whole language emphasises the meaning of literature for reading- and writing-learning, and considers the pupils reflection during their learning-process and conquered knowledge-goal. The whole language-theory and the LTG-method have a number of similarities and emanate from similar influences. Finally I insinuate that the LTG-method could be a part or a direction under the parasol of the whole language-theory.
Sammandrag
Syftet med studien är att studera läs- och skrivlärorna LTG-metoden och whole language-teorin. Avsikten är att utföra en komparativ litteraturstudie, för att urskilja de bådas likheter och olikheter, samt undersöka vilken av dem som är tydligast förankrad i kursplanen för svenska. Studiens utgångspunkt är frågeställningarna: Vilka likheter respektive skillnader har LTG och whole language-teorin? Vilken av dessa teorier finns tydligast förankrad i kursplanen för svenska? Studien har visat att såväl whole language-teorin som LTG-metoden kan förankras i kursplanen för svenska. Dock har whole language-teorin starkare fäste i kursplanen, då whole language-teorin betonar litteraturens betydelse för läs- och skrivinlärning, samt behandlar elevernas reflektion under deras inlärningsprocess och erövrade kunskapsmål. Whole language-teorin och LTG-metoden har en rad beröringspunkter, samt utgår från liknande influenser. Slutligen antyder jag att LTG-metoden skulle kunna vara en del eller en riktning under whole language-teorins parasoll.
Cavalcanti, Bruno Jácome. "Análise de modelos de predição de perdas de propagação em redes de comunicações LTE e LTE-Advanced usando técnicas de inteligência artificial." PROGRAMA DE PÓS-GRADUAÇÃO EM ENGENHARIA ELÉTRICA E DE COMPUTAÇÃO, 2017. https://repositorio.ufrn.br/jspui/handle/123456789/25061.
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A perfeita funcionalidade dos sistemas de comunicações de 3ª. e 4ª. gerações requerem, entre outras coisas, do conhecimento dos valores numéricos da predição das perdas de propagação dos sinais propagantes nos ambientes urbano, suburbano e rural. Portanto, o estudo das condições de propagação em um ambiente qualquer sempre será uma preocupação dos engenheiros projetistas. A análise e desenvolvimento de modelos robustos de predição de perdas de propagação em redes de comunicações Long Term Evolution (LTE) e Long Term Evolution Advanced (LTE-A) usando técnicas de Inteligência Artificial são realizadas neste trabalho. Os procedimentos metodológicos empregados foram aplicados no melhoramento da predição dos modelos de perda de propagação empíricos SUI, ECC-33, Ericsson 9999, TR 36.942 e o modelo do Espaço Livre, aplicados em redes LTE e LTE-A nas frequências de 800 MHz, 1800 MHz e 2600 MHz, para ambientes suburbanos em cidades de porte médio do nordeste do Brasil. Assim, nesta tese propõem-se dois modelos de Redes Neurais Artificiais (RNA): (i) o modelo de rede neural com entradas baseadas em erro (RNBE), utilizando como principal alimentador da rede o erro entre dados medidos e simulados, e, (ii) o modelo de rede neural com entradas baseadas no terreno (RNBT). O desempenho desses modelos foram comparados com os modelos de propagação considerados no trabalho e também as versões otimizadas utilizando Algoritmos Genéticos (AG) e o Método dos Mínimos Quadrados (LMS). Também foram realizadas comparações com valores medidos, obtidos a partir de uma campanha de medição realizada na cidade de Natal, Estado do Rio Grande do Norte. Os resultados finais obtidos através de simulações e medições apresentaram boas concordâncias métricas, com destaque para a performance do modelo RNBE. A principal contribuição dessa tese é que, ao utilizar essas técnicas que fazem uso de maneira mais eficiente dos modelos de propagação empíricos, pode-se estimar sinais propagantes realistas, evitando erros no planejamento e implementações de redes sem fio LTE e LTE-A em áreas suburbanas.
The perfect functionality of the 3rd and 4th generation of wireless systems requires, among other parameters, knowledge of the numerical values of the prediction of loss of propagation of propagation signals in urban, suburban and rural environments. Therefore, the study of propagation conditions in any environment will always be a concern of design engineers. The analysis and development of robust propagation loss prediction models in Long Term Evolution (LTE) and Long Term Evolution Advanced (LTE-A) communications networks using Artificial Intelligence techniques is performed in this work. The methodologies used were applied to improve the prediction of loss of empirical propagation SUI, ECC-33, Ericsson 9999, TR 36.942 models and the Free Space model applied in LTE and LTE-A networks in the frequencies of 800 MHz, 1800 MHz and 2600 MHz, for suburban environments in mid-sized cities in northeastern Brazil. Thus, in these thesis two models of Artificial Neural Networks (RNA) are proposed: (i) the neural network model with inputs based on error (RNBE) using as main feeder of the network the error between measured and simulated data, and (ii) the neural network model with land-based inputs (RNBT). The performance of these models was compared with the models of propagation considered in the work and also the versions optimized using Genetic Algorithms (AG) and the Least Square Method (LMS). Comparisons were also made with measured values, obtained from a measurement campaign carried out in the city of Natal, state of Rio Grande do Norte. The final results obtained through simulations and measurements presented good metric concordances, with emphasis on the performance of the RNBE model. Thus, the main contribution of this thesis is that, by using these techniques that make more efficient use of empirical propagation models, we can estimate realistic propagation signals, avoiding errors in the planning and implementations of LTE and LTE- A wireless networks in suburban areas.
Vargas, Reinoso Lenin Patricio. "Análisis comparativo entre LORAWAN y LTE en un escenario de red para la Internet de las cosas usando el software de simulación NS3." Tesis, Universidad de Chile, 2018. http://repositorio.uchile.cl/handle/2250/169977.
Full textLoRaWAN y LTE definen la coyuntura predominante como tecnologías de distribución para la Internet de las Cosas (IoT, Internet of Things). LoRaWAN define una red de largo alcance y baja potencia específica para servicios IoT, mientras que LTE tiene como objetivo satisfacer los requerimientos de la 3GPP (3rd Generation Partnership Project) para redes de cuarta generación (4G) y que a partir del Release 12 nace el concepto de LTE-M ya que empieza a considerar la comunicación tipo maquina (MTC, Machine Type Communication), el Release se enfoca en definir una nueva categoría de terminal manteniendo la misma red LTE pero considerando una configuración específica para dicho terminal. Es por eso que una comparación entre estas puede ayudar a entender las posibilidades que ofrecen. En este trabajo se desarrollan dos escenarios simulados en NS3 (Network Simulator 3) escritos en C++ usando módulos de LoRaWAN y LTE ya existentes dentro de la comunidad NS3, para que sean escenarios comparables la configuración del sistema es la misma para las dos tecnologías, excepto para la frecuencia (915MHz para LoRaWAN y 781MHz para LTE) y ancho de banda (250kHz para LoRaWAN y 1.4MHz para LTE) donde se procura configurar lo más cercanos posibles. Los parámetros considerados para evaluar las tecnologías son: throughput y packet lost, el área de cobertura será la variable para las distintas simulaciones. La topología de red de los escenarios es la misma para los dos casos y está comprendida por un gateway al cual se conectan hasta 100 sensores. La ubicación de los sensores puede ser en una área circular o en una área cuadrada, la ubicación circular es definida mediante un algoritmo que busca la ubicación óptima dentro de una área circular maximizando la distancia entre sensores; este algoritmo es escrito en Matlab. Los resultados obtenidos muestran que estadísticamente el desempeño de LoRaWAN es mejor que LTE en los escenarios propuestos: para una distribución óptima de sensores es 1302,7bps mayor en throughput y 64,85% menor en packet lost y para la ubicación en grilla cuadrada es 1292,24bps mayor en throughput y 64,58% menor en packet lost. El desempeño de la ubicación en el área circular es similar al desempeño de la ubicación en el área cuadrada (diferencias de 17,92bps y 7,46bps en throughput y 0,64% y 0,3% en packet lost).
Ramos, López Alexis Juan de Dios. "Efecto de la capitalización y tamaño de las instituciones financieras sobre el riesgo de liquidez en Perú para los años 2013-2019." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/653658.
Full textThis paper investigates the present effect of the size and capitalization of financial institutions on liquidity risk measured in two ways: the LTD ratio (loans / deposits), and the one provided by the SBS (liquid assets / short-term liabilities). 34 institutions are taken into account with monthly frequency data for the years 2013-2019 in Peru. For the purpose of the research, a fixed effects panel regression is used to capture the joint effect, then the sample is disaggregated by type of financial institution to evaluate the disaggregated impact of the variables by banking specialization. The results show that both variables have a direct (LTD) and inverse (RL) effect with liquidity risk, however, regarding capitalization, the effect is not as expected, even when broken down by bank specialization. The paper is divided into 6 sections: (1) introduction, (2) theoretical framework, where the financial system and the analysis of previous studies are addressed, (3) the objectives and hypotheses of the research, (4) the presentation and analysis of the data, (5) the results, the methodology used and the analysis with the previous studies, and finally (6) the conclusions of the present paper.
Trabajo de investigación
Asklund, Marie. "Läs- och skrivinlärningsmetoder : i teori och praktik." Thesis, Linköping University, Department of Educational Science (IUV), 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-655.
Full textAtt arbeta som lärare i de lägre skolåren innebär att ha ansvar för barnens läs- och skrivinlärning. Det finns flera metoder att utgå från i undervisningen och syftet med mitt arbete är att studera de vanligt förekommande metoderna. Genom att läsa litteratur hade jag ambitionen att ta reda på vilka huvuddrag och centrala tankar metodernas förespråkare står för och även hur metoderna kan användas i klassrummet. Dessutom har jag genom en empirisk studie studerat hur lärare i skolans verksamhet använder metoderna och vad de har för tankar om de olika arbetssätten. För att begränsa mitt arbete har jag studerat de vanligast förkommande metoderna; den syntetiska metoden, den analytiska metoden och LTG (läsning på talets grund).
Resultatet visar lärarna i sakolans verksamhet inte ser någon motsättning i att blanda olika metoder trots att enskilda forskare i den litteratur jag valt förespråkar en metod för läs- och skrivinlärningen. Lärarna plockar de bitar ur metoderna som de anser passar dem och de elever de har för tillfället.
Ziemke, Linnea, and Carolina Viström. "Vad krävs för att elever ska utveckla läs- och skrivkunskaper? : En litteraturstudie om inlärningsmetoder och lärarens betydelse." Thesis, Högskolan i Jönköping, Högskolan för lärande och kommunikation, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-39364.
Full textChapel, Anthony. "Etude du comportement photochimique de revêtements composites polymère/particules luminescentes pour applications à l'éclairage éco-énergétique à base de LEDS. Impact du vieillissement sur les performances optiques." Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22672/document.
Full textPhosphor-converted LEDs are emerging as an eco-friendly solution for the next generation lighting. Despite lifetimes claimed over 50 000h, a loss of the optical properties was noticed. This work focuses on the influence of photodegradation of the materials on the optical properties of the polymer/phosphor composite that is used to encapsulate the semiconductor chip. Luminescent composites were made from a polymer matrix (EVA or PMMA) and an inorganic phosphor: Y3BO6 :15% Eu3+. The evolution of physical, chemical and optical properties of these composites was investigated under irradiation in accelerated conditions (λ>300 nm) and in the use conditions of UV LED (λ=365 nm). The phosphor showed no pro-degrading effect on the photooxidation of the polymer. A loss of the optical properties of the composite was observed and ascribed to the photodegradation of the polymer in the case of the EVA matrix. The evolution of photometric parameters of the emitted light by the luminescent composite during photoaging can be attributed to the accumulation of photoproducts in films. However, for PMMA/phosphor composites, the chemical structure and optical properties of such composites are kept for accelerated photoaging time up to 4000h
Hiba, Abdallah. "Analyse multi-résidus de sulfonamides et de leurs métabolites dans les tissus d’origine animale." Thesis, Pau, 2014. http://www.theses.fr/2014PAUU3034.
Full textSulfonamides are amongst the most commonly used veterinary antibiotics. The uncontrolled exposure to sulfonamides upon consumption of meat products can be harmful to human health. In Lebanon, there are no current regulations that specify the safe levels of sulfonamides in animal products. In addition, no studies describing the presence of sulfonamides residues in their active or metabolized form in animal tissues exist. The analysis of residues at trace levels in complex matrices such as meat required the implementation of a rigorous sample preparation and analytical protocol that yields reproducible results at very low concentration levels. This thesis describes the development of two analytical methods for the determination of sulfonamides and their metabolites in animal tissues (e.g. poultry, sheep, pork) at trace levels. They are both based on an extraction step using QuEChERS extraction (Quick, Easy, Cheap, Effective, Rugged and Safe) followed by HPLC. In terms of mass analysers the use of LTQ-Orbitrap Velos and triple quadrupole MS/MS was optimized and the figures of merit were compared. The analytical methods were validated according to the EU decision (2002/657 / EC) criteria and by the participation in an inter-laboratory validation study organized by FAPAS (Food Analysis Performance Assessment Scheme). The methods were applied to carry out a monitoring study to detect and quantify residues of sulfonamides and their metabolites in more than 300 different samples of animal tissues derived from poultry, beef, sheep and pork collected from different regions of Lebanon
Ghaffar, Rizwan. "Atténuation d'interférence dans les systèmes multi-antennaires." Paris, Télécom ParisTech, 2010. http://www.theses.fr/2010ENST0030.
Full textAchieving enhanced spectral efficiency and increased reliability are the leading objectives of upcoming wireless systems. In the pursuit of these objectives, it is imperative to devise strategies taking into account the practical constraints so that the ensuing solutions are implementable in the real world. Our focus in this thesis is therefore on the practical communication systems. In the first part of the thesis, we consider low dimensional MIMO systems and propose a low complexity intelligent receiver structure for such systems. This receiver is based on the matched filter (MF) outputs and it successfully reduces one complex dimension of the system. We compare the proposed receiver with MMSE receiver and show that the proposed receiver is characterized by full diversity whereas MMSE receiver suffers from a loss of diversity. Moreover the proposed receiver has a coding gain whereas MMSE suffers from a coding loss. In the second part of the thesis, we look at interference suppression for the cell-edge users in cellular systems. We question the conventional Gaussian assumption for the interference in such scenario and emphasize that this interference has a structure that can be exploited in the detection process. In the last part of the thesis, we consider multi-user (MU) MIMO mode in long term evolution (LTE) systems. We propose a precoding strategy for low resolution LTE precoders which encompass geometrical interference alignment at the base station followed by the exploitation of the residual interference structure by the users
Bolin, Johansson Peggy, and Anna Larsson. ""... ett barn behöver alla metoder" : Lärares upplevelse av och inställning till metoder och hjälpmedel i läs- och skrivinlärning." Thesis, Linnéuniversitetet, Institutionen för pedagogik, psykologi och idrottsvetenskap, PPI, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-12675.
Full textCascant, López Miguel. "INFLUENCIA DE LA COMPOSICIÓN Y ESTRUCTURA DE LOS SUBSTRATOS DE SILICIO MONOCRISTALINO EN EL COMPORTAMIENTO ELÉCTRICO DE LAS CÉLULAS FOTOVOLTAICAS CRISTALINAS DE ALTA EFICIENCIA." Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/62356.
Full text[ES] Las características de los substratos sobre los que son fabricadas las células fotovoltaicas cristalinas constituyen un elemento fundamental en su comportamiento y durabilidad. En este sentido, la presencia de impurezas e imperfecciones en la red cristalina reduce el comportamiento eléctrico de los substratos limitando el potencial de generación eléctrica de las células. Esta limitación se acrecienta en las células de nueva generación, en las que su potencial para aumentar la eficiencia de conversión fotovoltaica solo puede hacerse efectivo al utilizar substratos con altas prestaciones eléctricas. En la presente investigación se ha procedido a la cristalización mediante la técnica Czochralski (Cz) de un lingote monocristalino, tipo p con resistividad en el rango de 0.7-2.1 Ohm.cm y tamaño industrial. Su posterior corte en obleas de 200 µm de espesor nominal ha permitido disponer de obleas distribuidas a lo largo del lingote en una fracción solidificada entre el 2.0% y el 99.4%. La caracterización del lingote ha incluido la medida de la resistividad así como la reconstrucción longitudinal y radial de su concentración en carbono, oxígeno y hierro. El reducido contenido en carbono obtenido ([C]<5E15 cm-3) contrasta con una elevada concentración en oxígeno intersticial (Oi) sin efectos apreciables en las propiedades eléctricas del lingote. Contrariamente, la reducción del tiempo de vida efectivo en la periferia y cola del lingote, es atribuido al aumento de la concentración en hierro intersticial [Fei] en dichas regiones. El estudio de la influencia de las difusiones en la evolución de las propiedades eléctricas del material incluyó difusiones de boro y fósforo mediante BCl3 y POCl3. El estudio ha constatado el efecto benéfico de la difusión de fósforo en la periferia del lingote asociado a la reducción del contenido en Fei. Por el contrario, se ha constatado el efecto perjudicial de la difusión de boro explicado en buena medida por un aumento superior a un orden de magnitud en [Fei]. La aplicación sucesiva de difusiones de boro y fósforo ha revelado una degradación apreciable en la cabeza del lingote tras la aparición de patrones circulares en la medida del tiempo de vida característicos de la precipitación de Oi. Se ha podido constatar la influencia de la elevada densidad de dislocaciones, observada en la cola del lingote, en la respuesta del substrato ante las difusiones. La fabricación de células de tecnología Al-BSF, con eficiencias comprendidas entre 17.8% y 18.2%, ha evidenciado una reducida influencia de las variaciones de las propiedades eléctricas del substrato en el comportamiento de las células finales. A su vez, la cartografía de la eficiencia quántica interna (IQE) y de la longitud de difusión (Ld) ha confirmado el efecto benéfico de la difusión de boro en la periferia y cola del lingote. La fabricación de células Passivated Emiteer Rear Totally-difused (PERT), ha permitido la obtención de dispositivos con eficiencias entre 18.8% y 19.6%. Las eficiencias muestran valores máximos en el centro del lingote y una reducción apreciable en la cabeza y cola.En una última etapa, se ha procedido a la fabricación de arquitecturas de células fotovoltaicas Al-BSF, PERT y Passivated Emitter Rear Contact (PERC), con el objetivo de estudiar los procesos de degradación y regeneración asociados a la formación de pares boro-oxígeno (B-O). El estudio de la evolución de Voc con el tiempo ha constatado una dependencia de la amplitud de degradación y cinética de regeneración con la arquitectura de célula. En este sentido se ha observado una degradación significativamente superior en las células PERC principalmente atribuible a una mayor sensibilidad a degradaciones de la calidad del substrato. A su vez se ha confirmado el potencial de los procesos de regeneración inducidos por la luz para suprimir de manera permanente los efectos de la degradación inducida por la for
[CAT] Les característiques dels substrats sobre els quals són fabricades les cèl·lules fotovoltaiques cristal·lines constitueixen un element fonamental en el seu comportament i durabilitat. En aquest sentit, la presència d'impureses i imperfeccions en la xarxa cristal·lina redueix el comportament elèctric dels substrats limitant el potencial de generació elèctrica de les cèl·lules. Aquesta limitació es veu augmentada en les cèl·lules de nova generació, en què el seu potencial per augmentar l'eficiència de conversió fotovoltaica només pot fer-se efectiu mitjançant la utilització de substrats amb altes prestacions elèctriques. En la present investigació s'ha procedit a la cristal·lització mitjançant la tècnica Czochralski (Cz) d'un lingot monocristal·lí, tipus p amb resistivitat en l'interval de 0.7-2.1 Ohm.cm i mida industrial. El seu posterior tall en oblees de 200 micres de gruix nominal ha permès disposar d'oblees distribuïdes al llarg del lingot en una fracció solidificada entre el 2.0% i el 99.4%. La caracterització exhaustiva del lingot ha inclòs la mesura de la resistivitat així com la reconstrucció longitudinal i radial de la concentració en carboni, oxigen i ferro. El reduït contingut en carboni obtingut ([C]<5E15 cm-3) contrasta amb una elevada concentració d'oxigen intersticial (Oi) sense efectes apreciables en les propietats elèctriques del lingot. Contràriament, la reducció del temps de vida efectiu dels portadors de càrrega a la perifèria i cua del lingot, és atribuïda a l'augment de la concentració en ferro intersticial [Fei] en aquestes regions. L'estudi de la influència de les difusions en l'evolució de les propietats elèctriques del material va incloure difusions de bor i fòsfor mitjançant BCl3 i POCl3. L'estudi ha constatat l'efecte benèfic de la difusió de fòsfor en la perifèria del lingot associat a la reducció del contingut en Fei. Per contra, s'ha constatat l'efecte perjudicial de la difusió de bor explicat en bona mesura per un augment superior a un ordre de magnitud en [Fei]. L'aplicació successiva de difusions de bor i fòsfor ha revelat una degradació apreciable en el cap del lingot després de l'aparició de patrons circulars en la mesura del temps de vida efectiu característics de la precipitació d'Oi. Igualment s'ha pogut constatar la influència d'una elevada densitat de dislocacions, observada a la cua del lingot, en la resposta del substrat davant les difusions. La fabricació de cèl·lules de tecnologia A-BSF, amb eficiències compreses entre 17.8% i 18.2%, va permetre evidenciar una reduïda influència de les variacions de les propietats elèctriques del substrat en el comportament de les cèl·lules finals. Al mateix temps, la cartografia de l'eficiència quàntica interna (IQE) i de la longitud de difusió (Ld) ha confirmat l'efecte benèfic de la difusió de bor en la perifèria i cua del lingot. La fabricació de cèl·lules Passivated Emiteer Rear Totally-difused (PERT), ha permès l'obtenció de dispositius amb eficiències entre 18.8% i 19.6%. Les eficiències mostren valors màxims al centre del lingot i una reducció apreciable en el cap i cua. En una última etapa, s'ha procedit a la fabricació d'arquitectures de cèl·lules fotovoltaiques Al-BSF, PERT i Passivated Emitter Rear Contact(PERC), amb l'objectiu d'estudiar els processos de degradació i regeneració associats a la formació de parells bor-oxigen (B-O). L'estudi de l'evolució de Voc amb el temps s'ha constatat una dependència de l'amplitud de degradació i cinètica de regeneració amb l'arquitectura de cèl·lula. En aquest sentit es va observar una degradació significativament superior en les cèl·lules PERC principalment atribuïble a una major sensibilitat a degradacions de la qualitat del substrat. Al mateix temps es va confirmar el potencial dels processos de regeneració induïts per la llum, per suprimir de manera permanent els efectes de la degradaci
Cascant López, M. (2016). INFLUENCIA DE LA COMPOSICIÓN Y ESTRUCTURA DE LOS SUBSTRATOS DE SILICIO MONOCRISTALINO EN EL COMPORTAMIENTO ELÉCTRICO DE LAS CÉLULAS FOTOVOLTAICAS CRISTALINAS DE ALTA EFICIENCIA [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/62356
TESIS
Diego, Maza William David. "Contrôle de trafic et gestion de la qualité de service basée sur les mécanismes IP pour les réseaux LTE." Thesis, Télécom Bretagne, 2016. http://www.theses.fr/2016TELB0406/document.
Full textThe mobile data landscape is changing rapidly and mobile operators are today facing the daunting challenge of providing cheap and valuable services to ever more demanding customers. As a consequence, cost reduction is actively sought by operators as well as Quality of Service (QoS) preservation. Current 3GPP standards for LTE/EPC networks offer a fine tuning QoS (per-flow level), which inherits many characteristics of legacy telco networks. In spite of its good performance, such a QoS model reveals costly and cumbersome and finally, it remains very rarely deployed, thereby giving way to basic best-effort hegemony. This thesis aims at improving QoS in mobile networks through cost-effective solutions; To this end, after an evaluation of the impact and cost of signaling associated with the standard QoS model, alternative schemes are proposed, such as the IP-centric QoS model (per aggregate) inspired from the DiffServ approach widely used in fixed IP networks. This model provides a simple, efficient and cost-effective IP level QoS management with a performance level similar to standardized solutions. However, as it requires enhancements in the eNB, this scheme cannot be expected in mobile networks before a rather long time.Thus, we introduce Slo-Mo, which is a lightweight implicit mechanism for managing QoS from a distant point when the congestion point (e.g. eNB) is not able to do it. Slo-Mo creates a self-adaptive bottleneck which adjusts dynamically to the available resources taking advantage of TCP native flow control. Straightforward QoS management at IP level is then performed in the Slo-Mo node, leading to enhanced customer experience at a marginal cost and short term
Wong, Bauhinia, and 黃沛珊. "Effects of serotonin on LPS- or LTA- stimulated cytokine release in monocytes and macrophages." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206489.
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Medicine
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Master of Medical Sciences
Mugnier, Nathalie. "Évolution de rétrotransposons à LTR dans les génomes de Drosophila melanogaster et Drosophila simulans." Lyon 1, 2007. http://www.theses.fr/2007LYO10105.
Full textDrosophila melanogaster and Drosophila simulans genomes have 10% to 15% of transposable elements. We present an analyses of the regulatory region of the LTR retrotransposon 412 within D. Melanogaster and D. Simulans populations. There is a variable amount of 412 element on the genomes of these populations. We discovered sub-families in some of these populations. We have then studied heterochromatic LTR retrotransposons in the sequenced genome of D. Melanogaster. The datation of these copies was execute in order to find variations in the retrotranspotion activity along times. This study allowed us to confirme that heterochromatin was subject to the recent vawe of transposition that happened in the D. Melanogaster genome this last 500 000 years ago
Wilhelm, Núñez Stephanie Soledad. "Mejoramiento de la gestión de carga viva en acopio Los Colorados, Minera Escondida Ltda." Tesis, Universidad de Chile, 2013. http://www.repositorio.uchile.cl/handle/2250/115267.
Full textEl Acopio Los Colorados de Minera Escondida posee un diseño inadecuado, de acuerdo a las características del mineral, el cual ha generado problemas tales como la formación de ratholes, la compactación sectorizada y la segregación de mineral. Consecuentemente, la carga viva del acopio es reducida y su autonomía se limita como máximo a 3 horas, lo que no representa un sistema flexible que permita desacoplar los procesos entre la mina y la planta concentradora. Por lo tanto una falla en el proceso aguas arriba impacta directamente la alimentación hacia las plantas. Se realizó un análisis de la situación base del Acopio, para determinar posibilidades de mejora, revisando las detenciones de la Planta Concentradora Los Colorados y de la planta de Chancado. Además se realizó una encuesta a los operadores de las áreas de Despacho, Chancado y Planta Concentradora para contrastar las necesidades y opiniones del personal de operaciones con los resultado obtenidos en el análisis de detenciones. Se identificó una serie de mejoras posibles de realizar para mejorar la continuidad operacional de la Planta Los Colorados, estas se clasifican en gestión de procesos, elaboración o mejoras de procedimientos, regulación de la comunicación e implementación de tecnologías. Estas mejoras se traducen en la redacción y puesta en marcha de protocolos de comunicación, el traspaso de la gestión del movimiento de los carros tripper hacia Chancado y Correas, la regulación del uso de los feeders, el mejoramiento del sistema de monitoreo de nivel, la instalación de un sistema supresor de polvo, y el aumento de la capacidad de empuje de los bulldozers que operan sobre el acopio. La regulación de las comunicaciones logra disminuir los tiempos de espera de chancado por camiones con mineral y regula el uso de los feeders, el traspaso de la gestión del movimiento de los carros tripper logra disminuir los tiempos de detenciones de chancado, el mejoramiento del sistema de monitoreo de nivel permite disminuir las detenciones por alto nivel de stockpile, el aumento de la capacidad de empuje de los bulldozers aumenta la autonomía del stockpile en caso de detenciones de chancado y el sistema supresor de polvo mejora la visibilidad para la operación de los bulldozers sobre el stockpile. El beneficio global que significan las mejoras implementadas corresponde a un potencial de alimentación de 2.7 millones de toneladas anuales hacia el Acopio Los Colorados, que aseguran la continuidad operacional de la Planta Concentradora.
Lartigue, Aurélia. "Les modèles murins de lupus erythemateux dissemine (LED) : rôle de l’immunité innée et de l’immunité spécifique." Rouen, 2008. http://www.theses.fr/2008ROUES009.
Full textSLE is an autoimmune disease characterised by the production of anti-nuclear Ab and immune complex formation which induce tissue lesions. Lupus disease in mice WB is associated with anti-phospholipid syndrome and risk of atherosclerosis development, we characterised Ab directed against nucleophosmin. This autoAb population is associated with presence of anti-cardiolipin Ab and could be responsible for vascular lesions. We showed that disease development is dramatically increased in B6lpr/lpr lupus mice knocked out for tlr9 and this protective role of TLR9 could be explained by its implication in anti-nucleosome Ab response. Inversely, clinical signs of the disease are improved in TLR2-/- and TLR4-/- mice suggesting a harmful effect of TLR2 and TLR4 due to their implication in B cell differentiation and more precisely in marginal zone B cell emergency
Florea, Alina Alexandra. "Optimisation de la transmission de phonie et vidéophonie sur les réseaux à larges bandes PMR." Phd thesis, Institut National des Télécommunications, 2013. http://tel.archives-ouvertes.fr/tel-00873686.
Full textStenquist, Elinor. "Barns läs- och skrivinlärning : Vilka delar hjälper barnen att lära sig läsa och skriva." Thesis, Mälardalen University, School of Education, Culture and Communication, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-8326.
Full textMitt syfte med denna uppsats är att ta reda på vad läs- och skrivinlärning innebär, både det som barn själva kan råda över och sådant som är yttre faktorer. Detta arbete bygger på studier inom litteratur, främst nyare forskning men vid studier av de olika metoderna har äldre böcker använts, då nyare inte fanns att få tag i.
Jag har först beskrivit de olika delarna som barn tillägnar sig när de ska lära sig läsa och skriva, sedan följer en beskrivning av tre olika metoder inom läs- och skrivinlärningen.
Min slutsats efter arbetets gång har inte tillfört forskningen något nytt eftersom det är en studie inom den litteratur som finns idag. Jag har däremot fått en bra grund att stå på i mitt arbete som lärare för de yngre åldrarna, när jag ska lära elever att läsa och skriva.
Borg, Jenny, and Sandra Nilmarkson. ""Konsten att ta russinen ur kakan" : läs- och skrivundervisning i skolans tidiga år." Thesis, Högskolan Kristianstad, Sektionen för lärande och miljö, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hkr:diva-13515.
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