• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 905
  • 337
  • 283
  • 183
  • 93
  • 78
  • 30
  • 21
  • 21
  • 12
  • 11
  • 10
  • 10
  • 7
  • 6
  • Tagged with
  • 2432
  • 406
  • 281
  • 216
  • 206
  • 161
  • 160
  • 160
  • 140
  • 138
  • 138
  • 131
  • 127
  • 122
  • 117
  • 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.
201

Μελέτη και υλοποίηση διαδικασιών τηλεελέγχου μέσω της χρήσης ασύρματων δικτύων

Τσομπανάκης, Αλέξανδρος 19 July 2012 (has links)
Η παρούσα διπλωματική εργασία κινήθηκε ανάμεσα σε δύο στόχους. Σε πρώτο επίπεδο είναι η παρουσίαση του κατάλληλου εξοπλισμού για τον τηλεέλεγχο υποδομών ευφυούς κατοικίας με τη βοήθεια ασύρματων τεχνολογιών, όπως το GSM. Δεύτερος στόχος είναι η θεωρητική μοντελοποίηση της συμπεριφοράς του καναλιού μετάδοσης σε εσωτερικό περιβάλλον, όσον αφορά την λαμβανόμενη ισχύ και τις απώλειες που προκαλούνται από το φαινόμενο της σκίασης. Στo πρώτο κεφάλαιο γίνεται παραμετροποίηση των υποδομών της ευφυούς κατοικίας Στο δεύτερο κεφάλαιο παρουσιάζονται οι πιο σημαντικές σύγχρονες ασύρματες τεχνολογίες, ενώ παράλληλα γίνεται μια επισκόπηση ως προς τα πρωτόκολλα για την υλοποίηση της ευφυούς κατοικίας. Στο τρίτο κεφάλαιο παρουσιάζουμε το δίκτυο GSM και προτείνουμε λύσεις και εφαρμογές πάνω στην ευφυή κατοικία .Στο τέταρτο κεφάλαιο γίνεται εκτενής αναφορά στα μοντέλα που περιγράφουν την ηλεκτρομαγνητική διάδοση για το εσωτερικό περιβάλλον που μας ενδιαφέρει. Σ’ αυτό το κεφάλαιο δίνεται μια πρώτη αίσθηση του σημαντικού ρόλου των απωλειών και πως αυτές επηρεάζουν τις επικοινωνίες γενικότερα. Επίσης, εστιάζουμε στις απώλειες που προκαλούνται από το φαινόμενο της σκίασης. Τέλος, στο πέμπτο κεφάλαιο προβαίνουμε στην πειραματική διαδικασία και την θεωρητική μοντελοποίηση της συμπεριφοράς του καναλιού μετάδοσης σε τοπολογία εσωτερικού σπιτιού, σε μια κατοικία στο κέντρο της Πάτρας, Πιο συγκεκριμένα, διεξήχθη μία επαλήθευση του μοντέλου απωλειών καναλιού ενός συστήματος 802.11g Wi-Fi λειτουργίας στα 2,4 GHz, όσον αφορά την λαμβανόμενη ισχύ και τις απώλειες που προκαλούνται από το φαινόμενο της σκίασης. Στα αποτελέσματα αναγνωρίσαμε ότι η μέθοδος, που βασίζεται στο μοντέλο απώλειας καναλιού Multi-Wall-Floor, παρέχει ένα πιο αξιόπιστο υπολογισμό της απόκλισης σκίασης. / The current thesis is moved between two targets: The first objective is the presentation of appropriate equipment for remote monitoring infrastructure of a smart home using wireless technologies such as GSM. The second objective is the theoretical modeling of the behavior of the transmission channel in indoor environment of the received power and the losses caused by the phenomenon of shadowing. In the first chapter we analyse the configuration of the smart home. The second chapter presents the most important modern wireless technologies and an overview on protocols for the implementation of smart home. The third chapter presents the GSM network and proposes solutions and applications using it on a smart home. The fourth chapter includes a comprehensive reference on models that describe the electromagnetic diffusion of the internal environment. This chapter gives a first sense of the important role of the path losses and how they affect communications in general. Also, we focus on losses caused by the phenomenon of shadowing. Finally, in the fifth chapter we conduct the experiment and theoretical modeling of the behavior of the transmission channel topology in domestic house, specifically a house in the center of Patras was chosen and we conducted a verification of the path losses model of 802.11g Wi-Fi in 2,4 GHz regarding the received power and the losses caused by the phenomenon of shadowing. The results showed that the method based on Multi-Wall-Floor Model path losses, provides a more reliable calculation of the deviation bands.
202

Images of Protest: The Barrier Wall Art of Ron English and Other Artists

Moorman, Michael 06 September 2017 (has links)
This thesis looks at illegal public art produced on state built barrier walls. The focus is on the artist Ron English, and his artworks produced on the Berlin Wall, Israeli Barrier Wall, and Mexican Border Fence. I examine English’s works in their respective contexts of Cold War divisions, the Israeli/Palestinian conflict, and tensions at the border between United States and Mexico. I also situate English’s works in relation to other artworks produced on these barriers. I argue that English is doing something different from other barrier wall artists in his work in Palestine and Mexico, offering a framework for understanding the primary motivations and tactics behind barrier wall art and highlighting English’s unique contributions.
203

A crise de Bretton Woods e a metamorfose do poder norte-americano : o início da transição da ordem internacional do pós-guerra / The Bretton Woods crisis and the US power metamorphosis : the beginnings of the postwar international order transition

Marchetto, Bruno Queiroz, 1984- 22 August 2018 (has links)
Orientador: Eduardo Barros Mariutti / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Economia / Made available in DSpace on 2018-08-22T16:05:36Z (GMT). No. of bitstreams: 1 Marchetto_BrunoQueiroz_M.pdf: 758262 bytes, checksum: f469466ab46d60dbac7a54b69302d82d (MD5) Previous issue date: 2013 / Resumo: Os efeitos da chamada "Era da Catástrofe" (1914-45) demandaram uma reforma radical nas diretrizes que nortearam a economia mundial no fim do século XIX: o laissez faire cedeu lugar à imposição de controles sociais sobre o mercado, orquestrados em grande medida pelos EUA. A materialização disto, no plano monetário-financeiro, foi à criação do sistema de Bretton Woods. Coube ao plano Marshall, mediante uma expansão da liquidez, dar o impulso inicial aos "Anos Dourados", fase de extraordinário crescimento econômico amparado pela busca do pleno emprego e pela sustentação da demanda. Os anos 1970 marcam a desarticulação deste arranjo internacional. Pretendemos analisar a estratégia monetário-financeira articulada pelos EUA no início da década de 1970, o que, no médio prazo, possibilitou a restauração de sua posição dominante no cenário internacional, promovendo, de forma correlata, a difusão do neoliberalismo e da financeirização. O ponto-chave de nossa análise está nas medidas adotadas pelos EUA para deslocar para seus "aliado-rivais" (Europa Ocidental e Japão) e para a periferia os efeitos adversos do "choque do petróleo", fato que tornou possível restaurar a sua liderança nos setores de ponta da indústria, que caracterizaram a Terceira Revolução Industrial. Partimos da hipótese que os EUA usaram fundamentalmente do seu poder político para deslegitimar as instituições multilaterais (o FMI e OCDE) que poderiam ter sido mobilizadas para conter a crise / Abstract: The "age of catastrophe" (1914-45) effects demanded radical reforms on the guidelines which shaped the world economy in the last years of the nineteenth century: the laissez faire was replaced by the imposition of social controls to the market mechanisms, process which was led, to a great extent, by US. The reflects of this movement, in the monetary and financial fields, was the creation of the Bretton Woods System. The Marshall Plan, through a liquidity expansion, gave the initial impulse to what came to be known as "the golden age of capitalism", a period of extraordinary economic growth characterized by the seek of the full employment and by the demand sustainment. The seventies began with the disarticulation of this international arrangement. We pretend to analyze the financial and monetary strategy articulated by the US in the begging of the seventies, what, in the middle run, made possible to this country to restore its dominant position on the international scenario, promoting, moreover, the neoliberalism diffusion and the "financialization" process. Our key point in this paper is the movements adopted by the US in order to dislocated to its "allies-rivals" (Western Europe and Japan) and to the periphery the adverse effects of the First Petroleum Chock (1973). The hypothesis assumed here is that the US basically used its political power to weaken the legitimacy of the multilateral institutions (the IMF and OEDC), which could have been mobilized to restrain the crisis / Mestrado / Historia Economica / Mestre em Desenvolvimento Econômico
204

Gravitropisme chez le peuplier : implication des kinases associées à la paroi (WAK) dans les évènements précoces après inclinaison / Poplar gravitropism : Implication of Wall Associated Kinase (WAK) in early events after tilting

Tocquard, Kévin 07 October 2016 (has links)
Les plantes adaptent leur croissance en fonction des facteurs environnementaux dont la gravité qui est un facteur constant. Une modification de l’orientation de la plante par rapport à l’axe de la gravité, i.e. une inclinaison induit une réponse de redressement : le gravitropisme. Pour les parties aériennes le gravitropisme est négatif, c’est-à-dire que les plantes vont adapter leur croissance dans la direction opposée à la gravité. Chez les arbres, le redressement est assuré par à la formation asymétrique d’un bois aux propriétés physico-chimiques particulières appelé le bois de réaction. Des récepteurs kinases pourraient participer à la perception et à la réponse précoce au stimulus gravitropique qu’est l’inclinaison. Parmi ces familles protéiques, les kinases associées à la paroi (WAK) sont des candidats intéressants. La liaison de ces protéines à la paroi permettrait de percevoir les déformations qui sont supposées se produire par l’inclinaison de la tige. Nous avons alors identifié et caractérisé pour la première fois la famille WAKs chez une espèce ligneuse, le peuplier, qui est composée de 175 membres. L’étude d’accumulation des transcrits WAKs a permis d’identifier les gènes WAKs qui s’expriment dans la tige puis l’expression de ces gènes a été suivie lors d’une cinétique après inclinaison. Il s’avère que les gènes WAKs sont faiblement exprimés et que 25% des gènes présentent une expression différentielle après inclinaison. Ces données transcriptomiques suggèrent que les WAKs participeraient aux événements cellulaires précoces après l’inclinaison de tiges chez le peuplier. Enfin, une étude plus approfondie a été initiée sur PtWAK70 qui est localisée dans le jeune xylème et le phloème secondaire. Nous avons également généré des outils moléculaires dont l’objectif est d’identifier les interacteurs potentiels de la partie apoplastique de PtWAK70. / Plants adapt their growth to environmental factors whose gravity is a continuous one. A modification of plant orientation by tilting leads to a straightening response: gravitropism. For aerial parts, plants will adapt their growth upward (negative gravitropism). In trees, straightening is accomplished through asymmetric formation of reaction wood which exhibits modifications in its physicochemical properties. Receptors-like kinases could play a role in both perception and early response to a gravitropic stimulus. Among them, Wall-Associated Kinases (WAKs) are interesting candidates because they are bind to the cell wall. They could detect wall deformations that are supposed to occur after tilting of the stem. We identified and characterized for the first time in a woody species (poplar) the largest WAKs family with 175 members. An extensive study of WAKs transcripts accumulation was carried out to identify genes expressed in woody stem. These genes expressions were analyzed during a kinetic after tilting. WAKs genes were overall weakly expressed but 25% of analyzed genes showed a modulation in their transcript accumulation after tilting. This suggests they could play a role in early events after tilting of poplar stems. Lastly, a deeper study was initiated on PtWAK70 which is localized in young xylem and secondary phloem. We generated molecular tools to identify potentials interactors of PtWAK70 apoplastic part.
205

Feedback control of resistive wall modes in the reversed field pinch

Yadikin, Dimitry January 2004 (has links)
A wide range of unstable current driven MHD modes is present in the re- versed τeld pinch (RFP) conτguration. An ideally conducting wall facing the plasma can stabilize the ideal MHD modes. In the presence of a resistive wall characterized by the wall time τw, fast mode rotation with the frequency exceeding the inverse wall time gives stabilization for resistive MHD modes. The ideal MHD modes in the RFP are non-rotating modes and can not be stabilized by the resistive wall. Instead they are converted into resistive wall modes (RWM) growing with a growth rate proportional to the inverse of the wall time τw. EXTRAP T2R is an RFP device equipped with a thin resistive wall having the wall time shorter than the plasma pulse duration τw < τp. This feature allows the study of non-resonant non-rotating resistive wall modes. Resistive wall modes dynamics has been studied in EXTRAP T2R . RWM growth rates has been measured and compared with linear MHD stability calculations. Quantitative agreement is observed. In the case τw < τp the RWM can cause discharge degradation and should be stabilized. Active feedback is the way to stabilize the RWM in the RFP. An intelligent shell scheme is one possible feedback scenario. An active feed- back system including a set of sensors and discrete active coils is installed in EXTRAP T2R. The intelligent shell tries to keep the magnetic flux zero at the positions of the sensor. The analog PID controller for the intelligent shell feedback scheme has been studied. A model of the active control system was developed and comparison with the experimental results showed good agree- ment. Encouraging experimental results on the active feedback stabilization of multiple RWMs in the RFP plasmas were obtained.
206

Análisis comparativo entre muros de concreto armado y muros Krainer para estabilizar el talud del río Rímac en San Juan de Lurigancho / Comparative analysis between reinforced concrete walls and Krainer walls to stabilize the slope of the Rímac river in San Juan de Lurigancho

Ramírez Chávez, Harry Alexander, Reupo Padilla, Carlos Gustavo 21 July 2020 (has links)
El río Rímac en épocas de avenidas suele socavar la ribera del río ocasionando deslizamientos del terreno que ponen en contante peligro a la población local. Para ello, se analizará dos propuestas de solución en un tramo de 150 metros en el talud del río Rímac, en el distrito de San Juan de Lurigancho. Las propuestas son una convencional y otra que por el momento no es muy conocida en nuestro país. La primera alternativa es la construcción de muros de concreto armado, debido a su alta efectividad en este tipo de problemática. La segunda alternativa, es la construcción de Muros Krainer, estos son un tipo de muro innovador, considerados como un método de bioingeniería que tiene como objetivo simular un muro de tierra armada. Se realizará un análisis estático y pseudoestático para cada tipo de muro en estudio. A su vez, el objetivo de dichos análisis es obtener el factor de seguridad, así como verificar el desempeño de este con los valores requeridos para cada muro con la ayuda de hojas de cálculos y herramientas computacionales. Por otro lado, se efectuará un análisis de costo con la conformación de análisis de precios unitarios para cada partida que requiere la elaboración de ambos muros. El producto del análisis estático y pseudoestático para los muros estudiados satisfacen los valores requeridos para su estabilidad. Sin embargo, el resultado del costo directo para la realización del muro Krainer resulto menor a comparación del costo directo del muro de contención de concreto armado. / The Rímac river in times of avenues usually undermines the riverbank causing landslides that endanger the local population. For this, two solution proposals will be analyzed in a 150-meter section on the slope of the Rímac river, in the San Juan de Lurigancho district. The proposals are one conventional and another that at the moment is not well known in our country. The first alternative is the construction of reinforced concrete walls, due to its high effectiveness in this type of problem. The second alternative is the construction of Krainer Walls, these are an innovative type of wall, considered as a bioengineering method that aims to simulate a reinforced earth wall. A static and pseudostatic analysis will be carried out for each type of wall under study. In turn, the objective of said analyzes is to obtain the safety factor, as well as verify its performance with the values required for each wall with the help of spreadsheets and computational tools. On the other hand, a cost analysis will be carried out with the formation of unit price analyzes for each item that requires the preparation of both walls. The product of the static and pseudostatic analysis for the studied walls satisfy the values required for their stability. However, the result of the direct cost for the realization of the Krainer wall was lower compared to the direct cost of the reinforced concrete retaining wall. / Tesis
207

Cylindrical Magnetic Nanowires Towards Three Dimensional Data Storage

Mohammed, Hanan 12 1900 (has links)
The past few decades have witnessed a race towards developing smaller, faster, cheaper and ultra high capacity data storage technologies. In particular, this race has been accelerated due to the emergence of the internet, consumer electronics, big data, cloud based storage and computing technologies. The enormous increase in data is paving the path to a data capacity gap wherein more data than can be stored is generated and existing storage technologies would be unable to bridge this data gap. A novel approach could be to shift away from current two dimensional architectures and onto three dimensional architectures wherein data can be stored vertically aligned on a substrate, thereby decreasing the device footprint. This thesis explores a data storage concept based on vertically aligned cylindrical magnetic nanowires which are promising candidates due to their low fabrication cost, lack of moving parts as well as predicted high operational speed. In the proposed concept, data is stored in magnetic nanowires in the form of magnetic domains or bits which can be moved along the nanowire to write/read heads situated at the bottom/top of the nanowire using spin polarized current. Cylindrical nanowires generally exhibit a single magnetic domain state i.e. a single bit, thus for these cylindrical nanowire to exhibit high density data storage, it is crucial to pack multiple domains within a nanowire. This dissertation demonstrates that by introducing compositional variation i.e. multiple segments along the nanowire, using materials with differing values of magnetization such as cobalt and nickel, it is possible to incorporate multiple domains in a nanowire. Since the fabrication of cylindrical nanowires is a batch process, examining the properties of a single nanowire is a challenging task. This dissertation deals with the fabrication, characterization and manipulation of magnetic domains in individual nanowires. The various properties of are investigated using electrical measurements, magnetic microscopy techniques and micromagnetic simulations. In addition to packing multiple domains in a cylindrical nanowire, this dissertation reports the current assisted motion of domain walls along multisegmented Co/Ni nanowires, which is a fundamental step towards achieving a high density cylindrical nanowire-based data storage device.
208

Viscoelastic Analysis of Double-wall and Triple-wall Thermoplastic Pipes

Al-Shawawreh, Sewar F. January 2021 (has links)
No description available.
209

Parametric Articulation

Newman, Andrew 11 October 2013 (has links)
No description available.
210

Plasma-Facing Components in Tokamaks : Studies of Wall Conditioning Processes and Plasma Impact on Diagnostic Mirrors

García Carrasco, Álvaro January 2014 (has links)
Understanding of material migration and its impact on the formation of co-deposited mixed material layers on plasma-facing components is essential for the development of fusion reactors. This thesis focuses on this topic. It is based on experiments performed at JET and TEXTOR tokamaks. The major objectives were to determine: (i) fuel and impurity removal from plasma-facing components by ICWC in different gas mixtures, (ii) fuel and impurity transport connected to ICWC operation, (iii) plasma impact on diagnostic mirrors. All these issues are in line with the ITER needs: mitigation of co-deposition and fuel inventory, and the performance of first mirrors in long-term operation. The novelty in research is demonstrated by several elements. In wall conditioning studies, tracer techniques based on injection of rare isotopes (N-15, O-18) were used to determine conclusively the impact of respective gases. Also, a new approach to ICWC was developed by combining global gas balance studies based on mass spectrometry and the use of multiple surface probes exposed to discharges and then studied ex-situ with accelerator-based techniques. Impact of plasma on diagnostic mirrors was determined after exposure to the entire first experimental campaign in JET-ILW. / <p>QC 20141103</p>

Page generated in 0.0308 seconds