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1
BRIVIO, FRANCESCO. "Search for the HH->bbtautau decay with the CMS experiment." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2019. http://hdl.handle.net/10281/241215.
Texte intégralRésumé :
Questa tesi descrive la ricerca di coppie di bosoni di Higgs nel canale di decadimento in cui uno dei due bosoni decade in una coppia quark-antiquark b e l'altro in una coppia leptone-antileptone tau. L'organizzazione della tesi segue fedelmente la struttura dell'analisi stessa e le strategie adottate per l'identificazione e la ricostruzione di eventi di segnale bbtautau. Sia l'ipotesi di produzione risonante che quella non risonante di una coppia HH sono sono prese in considerazione e analizzate utilizzando i dati raccolti dall'esperimento CMS nel 2016 e nel 2017 a un'energia nel centro di massa di 13 TeV. Dopo la scoperta, nel 2012, del bosone di Higgs, lo sforzo collettivo della comunità scientifica di fisica delle alte energie si è concentrato sulla caratterizzazione di questa particella. In questo contesto, le ricerche relative alla produzione di coppie di bosoni di Higgs giocano un ruolo fondamentale dal momento che permettono di osservare direttamente l'accoppiamento triplo dell'Higgs, misura altrimenti infattibile in altre analisi. Tale grandezza è, insieme alla massa del bosone stesso, l'unico parametro necessario a descrivere il potenziale del campo di Higgs e a permettere una profonda comprensione del meccanismo di rottura spontanea della simmetria all'origine della massa di tutte le particelle. Allo stesso tempo, dato il ridotto rate di produzione di coppie HH, qualunque deviazione dalla predizione teorica del Modello Standard implicherebbe notevoli cambiamenti nella cinematica e nel rate di produzione stesso, rendendo queste analisi estremamente sensibili a effetti di Nuova Fisica. Il canale di decadimento bbtautau rappresenta uno dei più interessanti stati finali nell'esplorazione di eventi con due bosoni di Higgs poichè caratterizzato da un branching fraction piuttosto elevato e relativamente poco affetto dalla contaminazione dei fondi. Allo stesso tempo però, questo canale presenta alcune problematiche di non triviale soluzione, come ad esempio la ricostruzione del decadimento dei leptoni tau che coinvolge l'emissione di neutrini. Questo rende necessario lo sviluppo di dedicate tecniche e algoritmi per l'identificazione e ricostruzione degli eventi di segnale. Nessun eccesso di eventi è osservato nell'analisi di 35.9/fb di dati raccolti nel 2016 e i risultati sono consistenti con l'ipotesi di solo fondo predetta dallo SM.
Limiti superiori di esclusione al 95% di livello di confidenza sono dunque calcolati relativamente al prodotto della sezione d’urto e del branching ratio. Nel caso dell'analisi risonante tali limiti variano da 500 a 5 pb in funzione dell'ipotesi di massa della risonanza testata, mentre nel caso non risonante i limiti attesi ed osservati corrispondono a 25 e 30 volte, rispettivamente, la predizione del Modello Standard. Un'ulteriore interpretazione dei limiti non risonanti è data nel contesto di teorie effettive (EFT), al fine di esplorare modelli in cui gli accoppiamenti del bosone di Higgs sono differenti da quelli previsti nello Standard Model.
Data la ridotta sezione d'urto di produzione di coppie di bosoni di Higgs, le analisi HH sono limitate dalla statistica disponibile, per questo, dopo il notevole risultato dell'analisi dei dati 2016, l'attenzione delle analisi HH a CMS è rivolta all'inclusione nelle ricerche della totalità dei dati raccolti durante il Run II e corrispondenti a circa 160/fb.
L'aver lavorato a questa analisi sin dal suo inizio mi ha permesso di partecipare attivamente allo sviluppo di nuove strategie e di capire quali sono gli aspetti più critici dell'analisi stessa sui quali è necessario concentrare gli sforzi per massimizzare la sensitività. In ogni Sezione di questa tesi quindi, affiancherò alla descrizione delle tecniche utilizzate nel 2016, i cambiamenti e i miglioramenti apportati durante lo studio dei dati 2017 in vista dei risultati futuri, prima per il Run II e, in una prospettiva più ampia per la fase ad alta luminosità di LHC.<br>This thesis describes the search for Higgs boson pairs in the final state composed of two b quarks and two tau leptons. The structure of this dissertation closely follows the workflow of the analysis and the strategies adopted to identify and reconstruct the bbtautau signal candidates. Both the resonant and the non-resonant double double Higgs production mechanisms are explored with the data collected by the CMS experiment during 2016 and 2017 at a center of mass energy of 13 TeV. After the discovery of the Higgs boson in 2012 by the ATLAS and CMS collaborations, the collective efforts of the high energy physics community have been focused on a precise characterization of this particle. In this context, HH searches play a fundamental role as they represent the only way to measure the Higgs boson trilinear self coupling. This variable is, together with Higgs mass, the only parameter needed to fully describe the Higgs field potential, thus allowing a better understanding of the electroweak symmetry breaking mechanism, which is at the base of the masses of all particles.
At the same time, given the low production rate of HH pairs, any deviation from
the theoretical predictions of the Standard Model would lead to sizeable changes
in both the event kinematics and in the production rate itself, thus making
double Higgs searches extremely sensitive to New Physics effects. The bbtautau final state represents one of the most interesting channels to explore double Higgs processes, given the high branching ratio and the relatively small background contamination. At the same time however, this final state poses some non trivial experimental challenges such as the reconstruction of the tau lepton decay that involves the presence of hardly detectable neutrinos. This has prompted the development of specific algorithms and techniques to identify and reconstruct the signal events and to maximize the analysis sensitivity. No excess of events is observed in the analysis of 2016 data, corresponding to an integrated luminosity of 35.9/fb, and the results are found to be consistent with the Standard Model background predictions. Exclusion upper limits at 95% Confidence Level are thus set on the cross section times branching fractions.
In the resonant search case, the limits vary from 500 to 5 pb depending on the mass of the signal resonance hypothesized, while in the non-resonant search, the observed and expected exclusion limits are set to about 30 and 25 times the theoretical Standard Model prediction, respectively. A further interpretation of the non resonant results is given in the context of effective field theories (EFT) in order to explore models that predict the modification of the Higgs couplings values. As double Higgs production rate is very small at the LHC, HH analyses are currently mainly limited by the available statistics and are expected to become more and more sensitive with the increase of the integrated luminosity collected. After the success of the 2016 results and in order to fully exploit the statistical power offered by the data, the bbtautau analysis strategy is now set on the combination of the full 2016-2018 statistics, that amounts to about 160/fb. Having collaborated to this analysis since the beginning or Run II, I was able to witness and actively participate in the changes and developments put in place during the 2016 data analysis, and to understand and learn the most critical aspects on which to focus our efforts in the future. Hence, each Section of this thesis is complemented with the changes introduced in the analysis workflow in 2017 and with ideas on how to further
improve the performance and sensitivity on the road to the study of the full
Run II statistics and, in a more wide perspective, of the High Luminosity phase of the LHC.
2
Schoeck, Kenneth O. "HIGH SPEED DOUBLE DENSITY RECORDING." International Foundation for Telemetering, 1986. http://hdl.handle.net/10150/615564.
Texte intégralRésumé :
International Telemetering Conference Proceedings / October 13-16, 1986 / Riviera Hotel, Las Vegas, Nevada<br>The Western Space and Missile Center has requirements to record high bit rate PCM telemetry data in both predetection and post-detection formats. Recording time is inadequate using standard wideband instrumentation magnetic tape recorder/reproducers. Using double density recording technology, recording time can be doubled, but results in some degradation in recorder performance. This paper discusses the effects of double density recording on recorder performance and on the quality of high bit rate telemetry data.
3
Herquet, Michel. "A two-Higgs-doublet model : from twisted theory to LHC phenomenology." Université catholique de Louvain, 2008. http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-08212008-163854/.
Texte intégralRésumé :
At the dawn of the Large Hadron Collider era, the Brout-Englert-Higgs mechanism remains the most appealing theoretical explanation of the electroweak symmetry breaking, despite the fact that the associated fundamental scalar boson has escaped any direct detection attempt. In this thesis, we consider a particular extension of the minimal Brout-Englert-Higgs scalar sector implemented in the Standard Model of strong and electroweak interactions. This extension, which is a specific, "twisted", realisation of the generic two-Higgs-doublet model, is motivated by a relative phase in the definition of the phenomenologically successful CP and custodial symmetries. Considering extensively various theoretical, indirect and direct constraints, this model appears as a viable alternative to more conventional scenarios like supersymmetric models, and gives grounds to largely unexplored possibilities of exotic scalar signatures at present and future collider experiments.
4
Moselle, Dagmara W. "A double-pole high voltage high current switch." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Dec%5FMoselle.pdf.
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Gilbertson, Steve. "Double optical gating." Diss., Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/4250.
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Ritchie, Stephen John Kerr. "The high speed double torsion test." Thesis, Imperial College London, 1996. http://hdl.handle.net/10044/1/11437.
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7
Normand, Louis. "Development of a double-sided silicon pad detector." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=68230.
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In ultra-relativistic heavy ion collisions, the centrality of a collision is measured by the total charged particle multiplicity while the distribution of these particles in rapidity space is a reflection of the thermodynamical conditions and the hadronization processes in the collision volume. As one of the R & D projects for the PHENIX experiment at RHIC, a double-sided Si $p sp+nn sp+$ junction pad detector is developed. One side of the detector measures the particle distribution and the other side the total multiplicity. A prototype detector made of 7.6 cm diameter, 300 $ mu$m thick Si wafer with 512 pads on one side and 16 larger pads (petals) on the opposite side has been successfully developed, constructed and tested, both in-beam and off-beam at the Brookhaven National Laboratory. The detector, the results as well as the Monte-Carlo simulation comparisons are presented.
8
Ljungberg, Stefan. "High Frequency Oscillations at an Electric Double Layer." Thesis, KTH, Rymd- och plasmafysik, 1995. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91579.
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Reynolds, Alastair P. "A spectroscopic study of high mass X-ray binaries." Thesis, University of St Andrews, 1992. http://hdl.handle.net/10023/14509.
Texte intégralRésumé :
Observations of four massive x-ray binary stars are presented, based on data accumulated between February 1989 and August 1991. Using modern techniques of spectroscopic data analysis, velocity curves are derived for three of these systems. Two of these curves (SMC X-1, QV Nor) yield very precise mass estimates for the component stars, while the third (Cen X-3) offers a constraint on the possible masses. The fourth system (X Per) is not shown to exhibit periodic variations, despite an extensive study conducted over more than two years. For the two systems that yielded precise masses, the component neutron stars are shown to lie within the theoretical mass range based on theories of their formation via the supernova explosion of a helium star in a close binary system. This is a marked improvement on previous studies where both stars had estimated masses which lay well outside of the expected range. The derivation of these masses incorporates the use of non-Keplerian velocity corrections, arising from the non-spherical, asymmetrically illuminated primary stars. A study of the line profiles showed that the temperatures around both primary stars were consistent with the parameters in these calculations. For the third system, the inaccuracy of the published ephemeris resulted in a lack of observations at the times of maximum and minimum velocity. The semi-amplitude is thus not well constrained, but it is shown that the observations are consistent with the assumption of a normal mass neutron star secondary. The system is shown to have undergone a gradual decrease in its orbital period which follows a parabolic trend, suggesting substantial mass-transfer. For the fourth system, a periodicity analysis of 130 spectroscopic velocity measurements of a Be star, via Fouriergram and string-length techniques, failed to highlight any strong periodicity. The scatter in the data appears larger than would be expected for a non-variable B star. The absence of periodic velocity variations at the expected period is discussed in terms of the binarity (or otherwise) of the Be star. A transition from Be to shell-star or ordinary B star phase occurred during the study, which is not evident from the spectral variations observed in the blue.
10
Wheel, Marcus A. "High speed double torsion testing of pipe grade polyethylenes." Thesis, Imperial College London, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318493.
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Zhao, Rui. "Double resonant high-frequency converters for wireless power transfer." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/22958/.
Texte intégralRésumé :
This thesis describes novel techniques and developments in the design and implementation of a low power radio frequency (40kHz to 1MHz) wireless power transfer (WPT) system, with an application in the wireless charging of autonomous drones without physical connection to its on-board Battery Management System (BMS). The WPT system is developed around a matrix converter exploiting the benefits such as a small footprint (DC-link free), high efficiency and high power density. The overall WPT system topology discussed in this thesis is based on the current state-of-the-art found in literature, but enhancements are made through novel methods to further improve the converter's stability, reduce control complexity and improve the wireless power efficiency. In this work, each part of the system is analysed and novel techniques are proposed to achieve improvements. The WPT system design methodology presented in this thesis commences with the use of a conventional full-bridge converter. For cost-efficiency and to improve the converters stability, a novel gate drive circuit is presented which provides self-generated negative bias such that a bipolar MOSFET drive can be driven without an additional voltage source or magnetic component. The switching control sequences for both a full-bridge and single phase to single phase matrix converter are analysed which show that the switching of a matrix converter can be considered to be the same as a full-bridge converter under certain conditions. A middleware is then presented that reduces the complexity of the control required for a matrix converter and enables control by a conventional full-bridge controller (i.e. linear controller or microcontroller). A novel technique that can maximise and maintain in real-time the WPT efficiency is presented using a maximum efficiency point tracking approach. A detailed study of potential issues that may affect the implementation of this novel approach are presented and new solutions are proposed. A novel wireless pseudo-synchronous sampling method is presented and implemented on a prototype system to realise the maximum efficiency point tracking approach. Finally, a new hybrid wireless phase-locked loop is presented and implemented to minimise the bandwidth requirements of the maximum efficiency point tracking approach. The performance and methods for implementation of the novel concepts introduced in this thesis are demonstrated through a number of prototypes that were built. These include a matrix converter and two full WPT systems with operating frequencies ranging from sub-megahertz to megahertz level. Moreover, the final prototype is applied to the charging of a quadcopter battery pack to successfully charge the pack wirelessly whilst actively balancing the cells. Hence, fast battery charging and cell balancing, which conventionally requires battery removal, can be achieved without re-balance the weight of the UAV.
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Cheng, HsienHui. "HIGH EFFICIENCY DOUBLE TWIST PANCHARATNAM PHASE OPTICAL BEAM DEFLECTORS." Kent State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=kent1437514337.
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Edwards, Philip Gregory. "A search for ultra high energy gamma ray emission from binary X-ray systems." Title page, contents and summary only, 1988. http://web4.library.adelaide.edu.au/theses/09PH/09phe266.pdf.
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Muhic, Dino. "Improved energy efficiency in double disc chip refining." Licentiate thesis, Mittuniversitetet, Institutionen för naturvetenskap, teknik och matematik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-12979.
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The electrical energy consumption in thermomechanical pulping (TMP) is very high, in the range of 2 – 3 MWh/adt depending on process solution and on the product quality specifications for the paper product. Both pulpwood and energy prices have increased rapidly for some time. Due to this, the main focus of the research and development is on ways to reduce the electrical energy consumption in wood chip refining. As a step towards a more energy and cost ‐ effective refining process, Holmen Paper AB has invested in a new mechanical pulping process at its Braviken mill. In this case the primary refining stage consists of high consistency (HC) double disc refiners ‐ RGP68DD (machines with two counter rotating discs). Earlier studies on the refining conditions, such as intensity and temperature, have indicated that it should be possible to improve the energy efficiency in double disc refining while maintaining the functional pulp properties such as tensile index. The main goal of this project was to improve the energy efficiency in double disc chip refining with 150 kWh/adt to corresponding pulp properties as measured on pulp samples after refiner. In order to further improve the basic understanding of what happens to the wood fibre material when changing the process conditions, the morphological and ultrastructural changes of fibres were also studied. This part of the research work was performed in cooperation with the research program; Collaborative Research on the Ultrastructure of Wood Fibres (CRUW). This licentiate project is a part of a large development project where different techniques to improve the energy efficiency has been evaluated by means of mill scale trials at the Holmen Paper Braviken Mill. The high consistency double disc chip refining part of the project was financed by The Swedish Knowledge Foundation, Metso Paper and Holmen Paper, in cooperation with FSCN (Fiber Science & Communication Network) at Mid Sweden University. The trials were made on one of the TMP lines at the Holmen Paper Braviken mill with Norway spruce as raw material. The influence of increased specific refining energy on pulp properties were studied at different refining temperatures, refining intensity, pulp consistency and production rate. Results from these trials were later validated by means of long term trials. Intensity models and simulations for intensity changes by new segment design were made by Juha‐ Pekka Huhtanen from Tampere University of Technology, Finland. The results show that the specific energy consumption to same tensile index can be improved by means of increasing the refining pressure/temperature. The energy efficiency was improved by 80 ‐150 kWh/adt depending on load and the inlet‐ and housing pressure. The largest relative specific energy efficiency improvement was reached at low specific energy consumption levels. Similar fibre surface ultrastructure characteristics are gained by pulps with high pressure/temperature and low specific energy consumption compared to low pressure/temperature and high specific energy consumption pulps. High pressure/temperature and high specific energy consumption resulted in significantly increase in the delamination/internal fibrillation of pulp fibres. The surface ultrastructure of these fibres exhibited exposed S2 layer with long ribbontype fibrillation compared to pulps produced with lower temperature and lower specific energy consumption. When the refiner was operated at high pressure, the tensile index was preserved over the whole plate life. The specific light scattering coefficient increased with increasing pressure/temperature. A reason for this could be increased intensity caused by decreased plate gap. Increased intensity by means of refiner segment design changes resulted in large specific light scattering coefficient increase at similar tensile index, lower shives content, lower average fibre length and lower CSF at same specific energy consumption. The fresh steam consumption was reduced by the increased refiner ressure/temperature.<br>Den höga elenergiförbrukningen vid produktion av mekanisk massa har ställtkrav på mer forskning för att elenergieffektivisera raffineringsprocessen. Som ettsteg mot en mer energi‐ och kostnadseffektiv raffineringsprocess, har HolmenPaper AB investerat i en ny tillverkning av termomekanisk (TMP) massa vidBravikens pappersbruk. Dubbeldiskraffinörerna i den nya massalinjens primäraraffineringssteget studerades i detta projekt. Det finns goda indikationer på att enminskning av energiförbrukningen är möjlig genom att studerar och optimeraraffineringparametrar såsom intensitet och temperatur. Projektets huvudmål varatt energieffektivisera det primära dubbeldiskraffineringssteget med 150 kWh/adttill motsvarande massaegenskaper, så som dragstyrka, mätt på massa efterraffinör. Tillfälle gavs också till att studera morfologiska förändringar på fibrer föratt ytterligare förstå hur massa och fibrerna påverkas av dubbeldiskraffinering ochförändringar i raffineringssystemet.Detta licentiatprojekt är en del av ett större projekt där olika tekniker för attförbättra energieffektiviteten har utvärderats i industriell skala på Holmen PaperBravikens pappersbruk. Licentiatprojektet är finansierat av KK‐stiftelsen, MetsoPaper och Holmen Paper, i samarbete med Mittuniversitetet.Fullskaleförsök gjordes på en av TMP linjerna vid Bravikens pappersbruk, därgran används som råvara. Studien utfördes på dubbeldiskraffinörerna i detprimära raffineringssteget. Malkurvor, med ökande specifik raffineringsenergi,gjordes vid olika raffineringstemperaturer, intensitet, massakoncentration ochproduktion. Resultat som erhållits från malkurvorna bekräftades med längrestudier på raffinörerna. Intensitetsmodeller och simuleringar utfördes av Juha‐Pekka Huhtanen från Tampere University of Technology.De erhållna resultaten visar på att energiförbrukningen till ett visst dragindexkan minskas genom att öka raffineringstrycket/temperaturen. Medraffineringstryck menas inlopp och hustryck i raffinören. Energibesparingen är iintervallet 80‐150 kWh/adt. Den största förbättringen kan uppnås vid lågaenergiinsatser. Massor producerade med högt tryck och temperatur och lägrespecifik energiförbrukning uppvisar liknande ultrastrukturella ytegenskaper sommassor producerade med lågt tryck och temperatur och hög specifik energi. Högttryck och temperaturer med hög specifik energiinsats gav en signifikant förbättringav delaminering/intern fibrillering av massafibrer. Dessa fibrer uppvisadebildningar av långa band‐liknande fibriller från fibrernas S2 skikt, i jämförelse medmassor tillverkade med lägre tryck och temperatur och lägre specifik energi.5Om raffineringen genomförs vid högt tryck/temperatur bevaras dragindexunder hela segmentlivslängden.Den specifika ljusspridningskoefficienten påverkades positivt av ökat tryck ochtemperatur. En orsak till detta kan vara högre intensitet som orsakas av minskadmalspalt.Ökad intensitet genom förändrad segmentdesign leder till stora ökningar i denspecifika ljusspridningskoefficienten. Samtidigt uppnås samma dragindex, lägrespethalt, lägre genomsnittlig fiberlängd och CSF vid samma specifikaenergiförbrukning.Förbrukningen av färskångan sänktes vid tillämning av högre tryck ochtemperatur i raffinören.
15
Steenson, David Paul. "The high-frequency application of double-barrier resonant tunnelling diodes." Thesis, University of Nottingham, 1993. http://eprints.nottingham.ac.uk/13957/.
Texte intégralRésumé :
The aim of this Thesis was to try to develop an understanding of the growth and fabrication of Double Barrier Resonant Tunnelling (DBRT) diodes, in order to enhance their properties at millimetre wave frequencies (ie. above 35GHz). Chapter 1 introduces the DBRT diode and outlines some of its applications while Chapter 2 describes aspects of device fabrication. Chapter 3 discusses the solid-state and quantum mechanical aspects which determine the DBRT's current-voltage characteristics and Chapter 4 describes an extensive parametric study relating the device properties to the high frequency behaviour. Chapter 5 covers the applications of DBRT devices at high frequencies and presents some of the results achieved so far. Besides the primary objective of studying the properties which determine the high frequency application of DBRT devices (via. the characterization of an extensive range of structures grown for the project), the other goal was to try to improve upon the results of other workers in terms of generating power and to improve the efficiency of up and down conversion at millimetre wave frequencies. Perhaps the most promising application of DBRT devices is as self-oscillating mixers (SOM) which can also provide conversion gain (due to the wide bandwidth of the negative differential resistance) at the intermediate frequency. This is of great importance since it negates the need to generate a local oscillator signal and dispenses with complicated image rejection mixer arrangements (for superheterodyne mixing) and amplification stages, which are very difficult to build and are expensive at millimetre wave frequencies. Whilst working in collaboration with staff at the University of Leeds, department of Electronic and Electrical Engineering a SOM was fabricated on microstrip which gave a modest gain at around 10GHz. Similarly a DBRT diode was operated in waveguide at 106GHz and provided -9.8dBm of power as measured on a spectrum analyzer. Both of these results represent (to the authors knowledge) the best results currently seen for DBRT devices in the UK and Europe.
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Penfold-Fitch, Zoë. "Measuring carbon nanotube double quantum dots using high frequency techniques." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709294.
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Chu, Rongming. "AlGaN-GaN single- and double-channel high electron mobility transistors /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202004%20CHU.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.<br>Includes bibliographical references (leaves 74-82). Also available in electronic version. Access restricted to campus users.
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Grant, Jackie. "Sphalerons in two Higgs doublet electroweak models." Thesis, University of Sussex, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341066.
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Watkins, Mark James. "High resolution spectroscopy and ab initio studies of weakly bound clusters." Thesis, University of York, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325780.
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Ellajosyula, Venugopal. "Search for a doubly charged Higgs boson decaying to same-sign W bosons in a triplet-doublet extension of the standard model with the Atlas detector at the LHC." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0477/document.
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La recherche de bosons scalaires de charge électrique +2 se désintégrant en deux bosons W de même charge est effectuée en analysant un échantillon de données collectées en 2015 et 2016 à une énergie de centre de masse de 13 Tev au LHC auprès du détecteur ATLAS, correspondant à une luminosité intégrée de 36.1 fb$^{-1}$. Cette recherche est motivée par un modèle comprenant une extension du secteur scalaire grâce à l'ajout d'un triplet. Il propose une explication à la masse des neutrinos et prédit une riche phénoménologie autour des bosons scalaires de charge +1 et +2 ainsi que des deux nouveaux bosons neutres, en plus d'un aux propriétés identiques à celles du boson de Higgs du MS. Le boson doublement chargé est produit par paires dans les collisions proton-proton et se désintègre majoritairement en bosons W. L'intervalle de masse exploré est situé entre 200 et 700 GeV, en utilisant des signatures expérimentales qui incluent plusieurs leptons, de l'énergie transverse manquante et des jets. L'analyse avec trois leptons dans l'état final est décrite dans cette thèse. Une combinaison de l'analyse avec deux, trois et quatre leptons est réalisée pour augmenter la sensibilité. Une interprétation statistique des résultats donne une limite inférieure en masse de 220 GeV. Ceci constitue la première recherche expérimentale de ce modèle dans cet espace de paramètres auprès d'un collisionneur<br>A search for doubly charged scalar bosons decaying to W boson pairs is performed using a data sample corresponding to an integrated luminosity of 36.1 fb$^{-1}$ collected by the ATLAS detector at the LHC at a centre-of-mass energy of 13 TeV in 2015 and 2016. The search is guided by a model including an extension of the scalar sector through a scalar triplet which provides an explanation of neutrino masses. Such a model predicts a rich phenomenology that includes singly- and doubly-charged bosons, and two new neutral bosons, besides a boson whose properties are identical to the SM Higgs boson. The doubly-charged bosons are produced by pairs in proton-proton collisions and decay predominantly into W bosons. The mass range from 200 to 700 GeV is explored using experimental signatures including several leptons, missing transverse energy and jets. The analysis in the final state of three leptons is described in this thesis. A combination of the analysis in two, three, and four leptons is used to enhance sensitivity. A statistical interpretation of the results gives an observed lower bound on the mass of 220 GeV. This is the first search of this model in this parameter space at the colliders
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Gordon, Nicole. "Cardiovascular response to intermittent high intensity double- and single-legged cycling." Thesis, Gordon, Nicole (2013) Cardiovascular response to intermittent high intensity double- and single-legged cycling. Honours thesis, Murdoch University, 2013. https://researchrepository.murdoch.edu.au/id/eprint/16281/.
Texte intégralRésumé :
Although the benefits of high-intensity interval training can be similar or superior to moderate- or low-intensity continuous training, it is possible that not all individuals should undertake such exercise. While high-intensity interval training is currently accepted practice within the cardiovascular rehabilitation setting, some individuals may not be suited to this type of exercise due to their decreased exercise tolerance and diminished cardiovascular function. The use of smaller muscle mass training (e.g. single-legged cycling) can allow localised high-intensity muscle training but avoid cardiac limitations associated with high blood flow demands when training using a large muscle mass. Purpose: To examine the differences in cardiovascular stress imposed by double- and single-legged high-intensity interval cycling in order to better understand the physiological responses of such exercise and assist in future training prescription. Methods: In a randomised crossover design, ten young, healthy individuals (23 ± 5 years of age, 180 ± 7 cm height, 74 ± 13 kg body weight, 51 ± 9 mL.kg-1.min-1) performed six 1-minute double-legged 'all out' efforts interspersed with 1-minute active recovery and twelve 1-minute single-legged (six with each leg) 'all out' efforts interspersed with 1-minute active recovery in two experimental sessions. Power output, oxygen consumption and heart rate were measured throughout the interval sessions. Blood pressure, oxygen saturation, ratings of perceived exertion, pain in the quadriceps and effort were measured at baseline and immediately following each interval. All self-perceived measures were taken on a 0 - 10 scale, with 0 = no perception and 10 = maximum perception. While brain natriuretic peptide (BNP) and left ventricular function were measured pre- and post-exercise. Results: Significantly greater power output (trial average: 340 ± 77 versus 301 ± 101 W, p<0.01) and workload (trial average: 916 ± 73 versus 743 ± 122 kJ, p<0.01) was observed during combined right and left single-legged cycling, when compared with double-legged cycling. Double-legged cycling resulted in greater physiological stress compared with single-legged cycling as shown by increased oxygen consumption (2.81 ± 0.69 versus 1.84 ± 0.43 L.min-1, respectively; p<0.01). Additionally, greater cardiac stress was observed during and resulting from double-legged cycling when compared with single-legged cycling as shown by increased inter-interval heart rate (161 ± 7 versus 142 ± 7 bpm, respectively, p<0.01) and systolic blood pressure (180 ± 17 versus 166 ± 21 mmHg, respectively, p<0.01) as well as lower end-session left ventricular ejection fraction (pre-post change: 11.5 ± 1.8 versus 2.6 ± 1.3 %, respectively; p<0.05). BNP increased pre- to post-exercise (24 ± 8 versus 27 ± 8 pg.mL-1), however, no differences were observed between conditions. Overall sessional perceived exertion was lower during single-legged, compared with double-legged cycling (7.2 ± 1.8 and 8.9 ± 0.7 units, respectively; p<0.02), even though inter-interval perceptions of exertion, pain and effort were similar between conditions. Conclusion: Single-legged cycling allows individuals to exercise at a greater overall power output; however, under reduced cardiovascular and physiological stress when compared with traditional double-legged cycling. Furthermore, single-legged cycling is perceived as easier, which could benefit compliance if used as a training stimulus. With increased attention placed on the use of high-intensity interval training in diseased populations, results of the present study indicate that single-legged cycling could provide an alternative approach to normal double-legged cycling giving practitioners a method to quickly enhance metabolic function while allowing individual to exercise with less risk of experiencing an adverse cardiac event.
22
Wade, Timothy Lawrence. "High power carbon based supercapacitors /." Connect to thesis, 2006. http://repository.unimelb.edu.au/10187/439.
Texte intégralRésumé :
Energy storage devices are generally evaluated on two main requirements; power and energy. In supercapacitors these two performance criteria are altered by the capacitance, resistance and voltage. (For complete abstract open document)
23
Xu, Boruo. "Detectors and physics at a future linear collider." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/270075.
Texte intégralRésumé :
An electron-positron linear collider is an option for future large particle accelerator projects. Such a collider would focus on precision tests of the Higgs boson properties. This thesis describes three studies related to the optimisation of highly granular calorimeters and one study on the sensitivity of Higgs couplings at CLIC. Photon reconstruction algorithms were developed for highly granular calorimeters of a future linear collider detector. A sophisticated pattern recognition algorithm was implemented, which uses the topological properties of electromagnetic showers to identify photon candidates and separate them from nearby particles. It performs clustering of the energy deposits in the detector, followed by topological characterisation of the clusters, with the results being considered by a multivariate likelihood analysis. This algorithm leads to a significant improvement in the reconstruction of both single photons and multiple photons in high energy jets compared to previous reconstruction software. The reconstruction and classification of tau lepton decay products was studied. Utilising highly granular calorimeters, the high resolution of energy and invariant mass of the tau decay products enabled a high classification rate. A hypothesis test was performed for expected decay final states. A multivariate analysis was trained to classify decay final states with a machine learning method. The performance of tau decay classification is used for the electromagnetic calorimeter optimisation at the ILC or CLIC. A proof-of-principle analysis using the correlation between the polarisations of the tau pair from a boson decay as a signature to differentiate the Higgs boson from the Z boson is presented. Sensitivity of Higgs couplings at CLIC was studied using the double Higgs production process. Algorithms were developed for signal event selection. The event selection relies on the jet reconstruction and the flavour tagging. A multivariate analysis is performed to select signal events. An attempt at extracting Higgs trilinear self-coupling and quartic coupling was conducted.
24
Ma, Yue. "Double-strand breaks (DSBs) and structure transition on genome-sized DNA." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13097333/?lang=0, 2018. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13097333/?lang=0.
Texte intégralRésumé :
DNA中の二本鎖切断(DSB)に対するアスコルビン酸(AA)およびDMSOの保護効果を、蛍光顕微鏡による巨大DNA(T4 DNA; 166kbp)の単分子観察によって評価した。凍結／解凍の状態に対して3つの異なる形態の放射源、可視光、γ線、および超音波の環境下にさらした。1‐プロパノールと2‐プロパノールの間で異なる効果が表れた。ゲノムDNA分子の高次構造の変化は、1−プロパノールを用いると、長軸長が濃度60％で最小を示し、次にアルコール含有量の増加と共に増加する傾向があることを見出した。一方、2−プロパノールを用いると、長軸長はアルコール含有量の増加と共にほぼ単調な減少を示した。<br>The protective effect of ascorbic acid (AA) and DMSO against double-strand breaks (DSBs) in DNA was evaluated by single-molecule observation of giant DNA (T4 DNA; 166kbp) through fluorescence microscopy. Samples were exposed to three different forms of radiation: visible light, γ-ray, and ultrasound or freeze/thawing. The change of the higher-order structure of genomic DNA molecules in the presence of alcohols by use of single DNA observation with fluorescence microscopy, by focusing our attention to unveil the different effect between 1-propanol and 2-propanol.<br>博士(工学)<br>Doctor of Philosophy in Engineering<br>同志社大学<br>Doshisha University
25
Colomer, Molines Raül. "Characterization of High-K Double Slot Grating Couplers for on-chip Interconnects." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-109310.
Texte intégralRésumé :
In this project, optical waveguides are analyzed with the intention of explain the principles of confine and guide light by using materials with a specific refractive index. The waveguide fabrication process in a silicon wafer is review as for the different type of devices or waveguides. Optical measurements within a double slot grating couplers are performed achieving a waveguide loss of 0.01dBm/μm and a total efficiency of 25.5% per grating coupler. And an attempt to explain the different phenomena that causes a detrimental effect in the results as cleanliness conditions, equipment or the Gaussian beam effect is done.
26
MIRANDA, CRISTINA VIDIGAL CABRAL DE. "FORECASTING HIGH FREQUENCY LOAD DATA USING A DOUBLE CYCLE HOLT WINTERS APPROACH." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=10512@1.
Texte intégralRésumé :
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>FUNDAÇÃO DE APOIO À PESQUISA DO ESTADO DO RIO DE JANEIRO<br>A previsão para dados de alta freqüência é fundamental
para a segurança e
confiabilidade da operação do sistema elétrico. Os métodos
de amortecimento
exponencial, em particular o método de Holt-Winters e suas
variações, são
apropriados para este contexto devido à sua alta
adaptabilidade e robustez. Este
trabalho visa à previsão a cada quinze minutos para sete
dias à frente, isto é, 672
passos à frente, para dados de energia elétrica de uma
concessionária da região
sudeste do Brasil. Para tanto, será utilizado o método de
Holt-Winters com dois
ciclos, que foi proposto recentemente por J. Taylor. Além
disso, será incluído o
tratamento de feriados e a influência da temperatura, que
serão aplicadas de forma
exógena ao modelo.<br>The forecast for high frequency data is fundamental for
the safety and
reliability of the electric power system operation. The
methods of exponential
smoothing, particularly the Holt-Winters approach and its
variations, are
appropriate for this type of data due to its highly
adaptability and robustness. This
work seeks to produce forecasts, every fifteen minutes,
for a time horizon of seven
days ahead, that is, 672 steps of fifteen minutes ahead,
for a brazilian load series
of an important distribution utility located in the
southeast region of the country. It
is considered the two-cycle version of the Holt-Winters
approach as proposed
recently by J. Taylor, including some improvements, such
as, the treatment of
bank holidays and the influence of temperature, acting as
exogenous inputs.
27
Boitrelle, Benjamin. "Development of a double-sided ladder for tracking in high-energy physics." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAE033/document.
Texte intégralRésumé :
Le projet PLUME développe des échelles ultra-légères inspirées par le cahier des charges du détecteur de vertex pour le futur e+e- International Linear Collider (ILC). Nos travaux montrent que, pour une énergie de 350 GeV et une luminosité de 250 fb-1, l’ILC donnera accès à des états finals comme Hνν. Les modules PLUME exploitent le concept d’échelles double-face recouvertes de capteurs CMOS afin d’atteindre un budget de matière de 0,35 % en longueurs de radiation. Les tests effectués ont montré que les performances électriques des 12 capteurs intégrés sur ces échelles ne sont pas dégradées. La surface des échelles présente des déformations, mais nous avons mis au point un algorithme spécifique qui permet de corriger leurs effets lors du traitement des données. Finalement, une mesure de la longueur de radiation d’un prototype moins avancé a été réalisée avec un faisceau test au DESY. La valeur obtenue de 0,47±0,02 % en longueurs de radiation correspond au budget attendu<br>The PLUME project develops ultra-light pixelated layers with specifications driven by the design of a vertex detector at the future e+e- International Linear Collider (ILC). The ILC will give access to final states like Hνν, as this work demonstrates for centre-of-mass energy 350GeV and a luminosity of 250 fb-1. PLUME devices exploit the concept of double-sided ladder spaved with thinned CMOS pixel sensors in order to reach a material budget of 0.35 % of radiation length. The present study validated that simultaneous operation of the 12 CMOS sensors integrated on such light ladders do not impact their electrical behaviour. Surface deformations were observed but a specific algorithm during the off- line analysis was proposed and successfully tested to preserve the native sensor spatial resolution. Finally, a measurement of the material budget of a less advanced ladder prototype has been performedat DESY test beam and yield 0.47±0.02 % of radiation length, matching the expected value
28
yin, jian. "High Temperature SiC Embedded Chip Module (ECM) with Double-sided Metallization Structure." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/30076.
Texte intégralRésumé :
The work reported in this dissertation is intended to propose, analyze and demonstrate a technology for a high temperature integrated power electronics module, for high temperature (e.g those over 200oC) applications involving high density and low stress.
To achieve this goal, this study has examined some existing packaging approaches, such as wire-bond interconnects and solder die-attach, flip-chip and pressure contacts. Based on the survey, a high temperature, multilayer 3-D packaging technology in the form of an Embedded Chip Module (ECM) is proposed to realize a lower stress distribution in a mechanically balanced structure with double-sided metallization layers and material CTE match in the structure.
Thermal and thermo-mechanical analysis on an ECM is then used to demonstrate the benefits on the cooling system, and to study the material and structure for reducing the thermally induced mechanical stress. In the thermal analysis, the high temperature ECM shows the ability to handle a power density up to 284 W/in3 with a heat spreader only 2.1x2.1x0.2cm under forced convection. The study proves that the cooling system can be reduced by 76% by using a high temperature module in a room temperature environment.
Furthermore, six proposed structures are compared using thermo-mechanical analysis, in order to obtain an optimal structure with a uniform low stress distribution. Since pure Mo cannot be electroplated, the low CTE metal Cr is proposed as the stress buffering material to be used in the flat metallization layers for a fully symmetrical ECM structure. Therefore, a chip area stress as low as 126MPa is attained.
In the fabrication process, the high temperature material glass and a ceramic adhesive are applied as the insulating and sealing layers. Particularly, the Cr stress buffering layer is successfully electroplated in the high temperature ECM by means of the hard chrome plating process. The flat metallization layer is accomplished by using a combined structure with Cr and Cu metallization layers.
The experimental evaluations, including the electrical and thermal characteristics of the ECM, have been part of in the study. The forward and reverse characteristics of the ECM are presented up to 250oC, indicating proper device functionality. The study on the reverse characteristics of the ECM indicates that the large leakage current at high temperature is not due to the package surrounding the chip, but chiefly caused by the Schottky junction and the chip passivation layer. Finally, steady-state and transient measurements are conducted in terms of the thermal measurements. The steady-state thermal measurement is used to demonstrate the cooling system reduction. To obtain the thermal parameters of the different layers in the high temperature ECM, the transient thermal measurement is applied to a single chip ECM based on the temperature cooling-down curve measurement.<br>Ph. D.
29
Durko, Heather Lynn. "Anamorphic Preclinical SPECT Imaging with High-Resolution Silicon Double-Sided Strip Detectors." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/321299.
Texte intégralRésumé :
Preclinical single-photon emission computed tomography (SPECT) is an essential tool for studying progression, response to treatment, and physiological changes in small animal models of human disease. The wide range of imaging applications is often limited by the static design of many preclinical SPECT systems. We have developed a prototype imaging system that replaces the standard static pinhole aperture with two sets of movable, keel-edged copper-tungsten blades configured as crossed (skewed) slits. These apertures can be positioned independently between the object and detector, producing an anamorphic image in which the axial and transaxial magnications are not constrained to be equal. We incorporated a 60 mm x 60 mm, millimeter-thick megapixel silicon double-sided strip detector that permits ultrahigh-resolution imaging. While the stopping power of silicon is low for many common clinical radioisotopes, its performance is sufficient in the range of 20-60 keV to allow practical imaging experiments. The low-energy emissions of ¹²⁵I fall within this energy window, and the 60-day half life provides an advantage for longitudinal studies. The flexible nature of this system allows the future application of adaptive imaging techniques. We have demonstrated ~225-μm axial and ~175-μm transaxial resolution across a 2.65 cm³ cylindrical field of view, as well as the capability for simultaneous multi-isotope acquisitions. We describe the key advancements that have made this system operational, including bringing up a new detector readout ASIC, development of detector control software and data-processing algorithms, and characterization of operating characteristics. We describe design and fabrication of the adjustable slit aperture platform, as well as the development of an accurate imaging forward model and its application in a novel geometric calibration technique and a GPU-based ultrahigh-resolution reconstruction code.
30
Lindahl, Viveca. "Detection Prospects of Doubly Charged Higgs Bosons from the Higgs Triplet Model at the LHC." Thesis, Uppsala universitet, Högenergifysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-155961.
Texte intégralRésumé :
In this thesis I explore the possibilities of detecting doubly charged Higgs bosons from the Higgs Triplet Model (HTM) at the Large Hadron Collider (LHC) at CERN. Higgs bosons are included into the Standard Model (SM) of particle physics in order to explain the origin of mass of the elementary particles. Even though the SM is considered to be a reliable starting point for any particle theory, no Higgs particles have to this day been found. There are therefore high expectations for the record-breaking energies of the LHC to lead to a Higgs discovery. The HTM produces seven different Higgs bosons, and among these we find the doubly charged ones. Because of their exotic charge, I focus on studying these Higgs particles in particular. To this purpose, I implement the full HTM theory as an alternative model option in standard particle physics Monte-Carlo software and then simulate LHC proton-proton collisions at a center of mass energy of 14 TeV. The investigated signal is defined as two like-signed leptons, four hard jets and missing energy in the final state. The main production mechanisms are pair-production and associated production with a singly charged Higgs. Since I choose to study a region of parameter space where the triplet vacuum expectation value is relatively large, the doubly charged Higgs decays into W's and the singly charged Higgs into WZ or tb. The results of the simulations show that the LHC could probe Higgs masses up to at least 300 GeV with an integrated luminosity of about 300 fb.1.
31
Sundu, Hayriye. "Lepton Flavor Violation In The Two Higgs Doublet Model." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608359/index.pdf.
Texte intégralRésumé :
The lepton flavor violating interactions are interesting in the sense that they are sensitive the physics beyond the standard model and they ensure considerable information about the restrictions of the free parameters, with the help of the possible accurate measurements. In this work, we investigate the lepton flavor
violating H+ ! W+l and the lepton flavor conserving H+ ! W+l decays in the general two Higgs doublet model and we estimate decay widths of these decays. After that, we analyze lepton
flavor violating decay !
i in the same model and calculate its branching ratio. We observe that the
experimental results of the processes under consideration can give comprehensive
information about the physics beyond the standard model and the existing free
parameters.
32
Banerjee, Arijit Ph D. Massachusetts Institute of Technology. "Switched-doubly-fed-machine drive for high power applications." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105650.
Texte intégralRésumé :
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 202-207).<br>Converting electricity to mechanical motion is a foundation of modern civilization. A controllable "knob" is often necessary in these electromechanical energy conversion systems to achieve adjustable motion or a process control. An energy-efficient approach to realize this "knob" is through variable-speed drives (VSD), which are power-electronic based converters with associated control operating as an interface between the electrical machine and the electrical source. These drives are not only critical in a wide range of applications including industrial processes, electric propulsion systems, and power generation plants but also becoming increasingly relevant for optimizing energy consumption. For example, a motor without a VSD running at fixed speed can potentially waste 30% to 80% of energy in mechanical throttles located upstream from a compressor or downstream of a pump. In addition to being a controllable knob for energy conversion, these VSDs are configurable to support the electrical source, e.g., the electric grid, through appropriate reactive power support and controllable power factor - a vital feature required for the future electric grid comprising more complex electrical networks. However, merely 13% of global loads in mega-watt class high-power applications are driven by VSDs. At these higher power levels, the VSD design is significantly challenging due to the limited available power-electronic device ratings and allowable switching frequency leading to design trade-offs among size, efficiency, performance, reliability, and cost. This dissertation proposes a switched-doubly-fed machine (switched-DFM) drive that uses a parallel architecture for electromechanical energy conversion to reduce the required power processing capability of the power-electronic converter by two-thirds while operating seamlessly over a wide speed range. Additionally, the proposed architecture provides exciting opportunities for supporting the electric grid with reactive power not only through the VSD but also using the electrical machine. The approach confronts the challenges of high power electromechanical energy conversion from the perspective of electromagnetics, power electronics, circuit designs, embedded computing, and control to push the trade-off boundary for the VSD to be physically small, efficient, reliable, flexible, inexpensive, and electric-grid friendly. The thesis contributions include a design procedure for the proposed switched-DFM drive based on a required drive-torque-speed capability, a control architecture that can achieve seamless performance across the entire speed range from the perspectives of the electrical grid and the mechanical load, multiple transfer-switch circuit topologies enabling uninterrupted on-the-fly reconfiguration of the DFM, steady-state and dynamic performance comparison between different switched-DFM drive topologies, and an exploration of DFM electromagnetic design considerations that suit the proposed architecture. A lab-scale experimental setup that emulates an entire power system from generation to consumption is designed and built to demonstrate seamless, wide-speed range, and four-quadrant operation of the proposed switched-DFM drive. The proposed methodologies open up opportunities to create efficient, cost-effective, and sustainable solutions for high power electromechanical energy conversion systems.<br>by Arijit Banerjee.<br>Ph. D.
33
Lebedev, Oleg. "Spontaneous CP-Violation in Two Higgs Doublet Supersymmetric Models." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30640.
Texte intégralRésumé :
An alternative approach to the problem of CP-violation
is presented. It is based on the possibility of
spontaneous CP-breakdown in models with two Higgs doublets.
General features of the phenomenon such as stability of the
vacuum and the existence of a light axion are discussed.
We investigate the feasibility of spontaneously broken
CP in the minimal supersymmetric models - the MSSM and
NMSSM. The latter is shown to be experimentally viable.
The phenomenological implications of the model such as
CP-violating effects in the kaon systems and a nonzero
neutron electric dipole moment are studied.<br>Ph. D.
34
Mellier, Carine. "Optimal Design of Bridges for High-Speed Trains : Single and double-span bridges." Thesis, KTH, Bro- och stålbyggnad, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-36354.
Texte intégralRésumé :
To deal with an increasing demand in transportation, trains are made longer and faster. Higher speeds imply higher impacts on bridges. Therefore, structures have to be designed to resist these new constraints. The Eurocode (2002) introduced additional checks for the design of high-speed railway bridges. Among them, the maximum vertical deck acceleration criterion often determines alone the design of the structure. Tests on shake table brought to the conclusion that vertical bridge deck acceleration should never exceed 3.5 m/s2 for ballasted tracks. This master thesis investigates the optimization of cross section parameters of single-track simply supported and double-span bridges based on the limit of the maximum vertical deck acceleration criterion. The first natural frequency is considered as a proof of the feasibility of the structure. The optimization is carried out through MATLAB for both types of bridges. The deck acceleration of simply supported bridges is analytically calculated using the Train Signature (ERRI D214 1999) in MATLAB. The dynamic calculations of double-span bridges are implemented through the finite element software ABAQUS. The implemented programs have been verified by comparison to values of simple cases found in the literature. Structures are tested under the influence of the ten HSLM-A trains of the Eurocode running at speeds between 150 km/h and 350 km/h. Optimization algorithms are presented and compared in this study but their applicability in such context is questioned. Indeed, as the problem contains several suitable minima, the algorithms, which end in one solution, are not adapted. To overtake this difficulty, a scanning of the interesting zone is advised. However, the latter is very time consuming, even more if the finite element analysis is used. Suggestions to decrease analysis time are presented in this report. Single span composite bridges with a span longer than 20 m appeared to be impossible to optimize within the objectives defined in this work (i.e. considering limits of deck acceleration and first natural frequency), which draws doubts about their suitability for high-speed railways. Nevertheless, simply supported bridges made of concrete seem more adapted for high-speed railways and their optimized parameters are presented in this work. Optimized parameters for double-span concrete bridges are also presented.
35
Mohiuddin, Muhammad. "InGaAs/InA1As Double Heterojunction Bipolar transistors for high-speed, low-power digital applications." Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.511942.
Texte intégral
36
Schneider, Karl. "Broadband amplifiers for high data rates using InP, InGaAs double heterojunction bipolar transistors." Karlsruhe : Univ.-Verl. Karlsruhe, 2006. http://deposit.d-nb.de/cgi-bin/dokserv?idn=979772826.
Texte intégral
37
Levillain, Maxime. "Double longitudinal spin asymmetries in single hadron photoproduction at high pT at COMPASS." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS059/document.
Texte intégralRésumé :
Cette thèse présente une nouvelle étude ayant pour but de contraindre la contribution du gluon au spin 1/2 du nucléon. Cette analyse se place dans le cadre théorique de la pQCD colinéaire pour calculer des asymétries de section efficaces pour des hadrons inclusifs à grande impulsion transverse (pT>1 GeV/c) dans le régime de photoproduction quasi-réel (Q^2<1 GeV^2). Ces calculs sont réalisés jusqu'à NLO (Next-to-Leading Order) avec une inclusion prévue de resommation des gluons au seuil jusqu'à NLL (texit{Next-to-Leading Logarithm}), qui n'est pour l'instant fait que pour le cas non-polarisé. Cela rend les asymétries sensibles non seulement à la fusion photon-gluon ("gamma^* g") mais aussi à des processus de photon résolu tel que "q g" ou "g g".La mesure des asymétries est réalisée pour toutes les données de COMPASS de 2002 à 2011 avec un faisceau de muons polarisés à 160-200 GeV diffusé sur une cible de deuterium (LiD de 2002 à 2006) ou de proton (NH3 pour 2007 et 2011). Ces asymétries sont présentées en fonction de pT et de la pseudorapidité eta (pT dans [1,4] avec = 3 (GeV/c)^2, et eta dans [-0.1,2.4]).Les calculs de resommation n'étant pas terminés pour le cas polarisé, les mesures sont seulement comparés aux calculs théoriques en utilisant différents jeux de parametrisations de fonctions de distribution de parton polarisées ayant des valeurs de DeltaG assez étendues. Ces comparaisons sont ensuite utilisées pour évaluer le DeltaG des mesures.De façon complémentaire à cette analyse, une étude sur de nouveaux détecteurs, les pixel Micromegas, servant à pister le passage des particules, a été réalisée. Après certaines calibrations, ces détecteurs montrent des résultats prometteurs aussi bien en terme d'éfficacité qu'en terme de résolution temporelle et spatiale<br>This thesis presents a new study aiming at constraining the gluon contribution DeltaG to the 1/2 nucleon spin. The collinear pQCD theoretical framework, on which it is based, deals with asymmetries calculated from cross-sections for single inclusive hadron in the regime of quasi-real photoproduction (Q^2<1 GeV^2) at high hadron transverse momentum (pT>1 GeV/c). These calculations are done up to Next-to-Leading order with a foreseen inclusion of Next-to-Leading logarithm threshold gluon resummation, only performed for the unpolarised cross-sections yet. This makes the asymmetries sensitive to the gluon polarisation not only through Photon Gluon Fusion ("gamma^* g") but also through resolved photon processes such as "q g" or "g g".The measurement of the asymmetries is performed for all the COMPASS data available from 2002 to 2011 with a polarised muon beam at 160-200 GeV scattered off a longitudinally polarised target of deuteron (LiD for 2002-2006) or proton (NH3 for 2007 and 2011). The asymmetries are presented in bins of pT and of pseudorapidity eta (p_T in [1,4]$ with = 3 (GeV/c)^2, and eta in [-0.1,2.4]).Since the resummation calculations are not completed yet for the polarised case, the measurements are only compared with theoretical calculations using different parametrisation sets of polarised Parton Distribution Functions with a large range of different DeltaG. This comparison is then used to evaluate the DeltaG of these measurements.Complementary to this analysis, a study of new tracking detectors, the pixelised Micromegas, is performed. After calibration, it shows promising efficiencies and time and spatial resolutions
38
Draper, Shane N. "PHYSIOLOGICAL RESPONSES TO SINGLE AND DOUBLE LEG CYCLING IN NORMOXIC AND HYPOXIC CONDITIONS." Kent State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=kent15242407803384.
Texte intégral
39
Berry, David W. "Design, Analysis and Experimental Verification of a Mechanically Compliant Interface for Fabricating Reliable, Double-Side Cooled, High Temperature, Sintered Silver Interconnected Power Modules." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/64898.
Texte intégralRésumé :
This research developed a double-side power electronics packaging scheme for high temperature applications exemplified by 1200 V, 150 A silicon devices. The power modules, based on both quarter and half-bridge topologies, were assembled using sintered silver device attachment rather than conventional solder alloys. Thermomechanical stresses in the double-side architecture were mitigated with a compliant layer fabricated from elliptical silver tubes.
This research presents an introduction to conventional packaging techniques and their weaknesses. These shortcomings provide the basis for a module design which improves upon module thermal management while also addressing electrical and reliability requirements. The optimum package design enhances heat dissipation with the addition of a substrate bonded to the top electrical pads of the semiconductor devices. The use of sintered silver also increases the useful application temperature by avoiding the creep failure mechanisms of solder alloys.
The modules were characterized extensively to quantify thermal and electrical performance. In the case of thermal characterization, the double-side architecture required multiple testing configurations to fully understand the parallel heat flow paths. These results were compared to models constructed using finite element analysis (FEA). The FEA models were also utilized for measurement of strains in multiple package designs to better determine the effects of increased compliance on the relative package cycling lifetime. These lifetimes were then assessed, in part, using experimental passive and cycling tests on functional double-side packages.
The resulting power modules exhibited significant decreases in thermal resistance when they are cooled, as designed, from both sides of the module. Even single sided cooling options reveal significant advantages and transient thermal impedance was found to be significantly lower. Power module models revealed the compliant layer was successful in reducing the device shear stresses which was experimentally validated through the use of DC power stage testing. It was found, through double pulse testing and electrical modeling, that parasitic inductances were reduced by utilizing planar bonding and planar symmetrical traces. Finally, modeling of the double-side package with added tube compliance revealed a decrease in plastic and shear strains when compared to other single and double-side package designs. This reduction directly translates to increased cycling lifetime using well known strain based fatigue models.<br>Ph. D.
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Ames, David E. II. "Configuration adjustment potential of the Very High Temperature Reactor prismatic cores with advanced actinide fuels." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4382.
Texte intégralRésumé :
Minor actinides represent the long-term radiotoxicity of nuclear wastes. As one
of their potential incineration options, partitioning and transmutation in fission reactors
are seriously considered worldwide. If implemented, these technologies could also be a
source of nuclear fuel materials required for sustainability of nuclear energy.
The objective of this research was to evaluate performance characteristics of Very
High Temperature Reactors (VHTRs) and their variations due to configuration
adjustments targeting achievability of spectral variations. The development of realistic
whole-core 3D VHTR models and their benchmarking against experimental data was an
inherent part of the research effort. Although the performance analysis was primarily
focused on prismatic core configurations, 3D pebble-bed core models were also created
and analyzed.
The whole-core 3D models representing the prismatic block and pebble-bed cores
were created for use with the SCALE 5.0 code system. Each of the models required the
Dancoff correction factor to be externally calculated. The code system DANCOFF-MCThe whole-core/system 3D models with multi-heterogeneity treatments were
validated by the benchmark problems. Obtained results are in agreement with the
available High Temperature Test Reactor data. Preliminary analyses of actinide-fueled
VHTR configurations have indicated promising performance characteristics. Utilization
of minor actinides as a fuel component would facilitate development of new fuel cycles
and support sustainability of a fuel source for nuclear energy assuring future operation of
Generation IV nuclear energy systems.
was utilized to perform the Dancoff factor calculations.
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Ghedjatti, Ahmed. "Etude structurale des nanotubes de carbone double parois." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066051/document.
Texte intégralRésumé :
Le nanotube de carbone double parois représente le cas idéal pour étudier la nature de l'interaction entre parois des tubes multiparois. En partant d'échantillons dispersés de DWNTs synthétisés par CVD, nous avons pu, grâce à la microscopie électronique en transmission haute résolution (METHR), établir une procédure robuste de détermination structurale des configurations. Il apparaît alors que certaines configurations structurales sont privilégiées alors que d'autres sont interdites, mettant en évidence les effets du couplage interparoi. À partir de simulations Monte Carlo réalisées sur des DWNTs de configurations interdites, nous avons montré que le tube interne modifie sa structure pour atteindre une stabilité énergétique, ce que nous avons pu rapprocher d'observations expérimentales. Pour étudier les propriétés électroniques des DWNTs observés expérimentalement, nous avons corrélé les techniques de METHR et d'absorption optique pour analyser des populations différenciées de tubes en nombre de parois, diamètre et nature électronique, grâce à la technique DGU (Ultracentrifugation de Gradient de Densité). À l'issue de trois tris successifs, nous avons pu isoler une population de tubes double parois pure à 95% et dont les tubes extérieurs sont de nature semi-conducteur à 90\%<br>Double-walled carbon nanotube represents the ideal case to investigate the nature of the interaction between walls of multiwall tubes. Starting with scattered samples of DWNTs synthesized by CVD, we have established a robust procedure for structure determination of configurations based on high resolution electron microscopy transmission (HRTEM). After achieving a statistical study, it appears that some structural configurations have been favored while others are completely forbidden, highlighting the effects of inter-wall coupling. To go beyond, we have performed Monte Carlo simulations at atomic scale on DWNTs with forbidden configurations. As a result, we have shown that the inner tube changes its structure to achieve energy stability, in good agreement with experimental observations. To study the electronic properties of DWNTs observed experimentally, we correlated HRTEM and optical absorption techniques for analyzing differentiated tubes populations by number of walls, diameter and electronic nature, thanks to the technical DGU (Density Gradient Ultracentrifugation ). After three successive sorting, a pure population of double-walled tubes to 95% and of which 90% of the outer tubes are semiconductor has been isolated
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Köhler, Michael [Verfasser], and Karl [Akademischer Betreuer] Jakobs. "Double-sided 3D silicon detectors for the high-luminosity LHC = Doppelseitige 3D-Siliziumdetektoren für den High-Luminosity LHC." Freiburg : Universität, 2011. http://d-nb.info/1123462038/34.
Texte intégral
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Brawn, Gary Derrick. "Symmetries and topological defects of the two Higgs doublet model." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/symmetries-and-topological-defects-of-the-two-higgs-doublet-model(a8cafde7-383a-4190-a30e-0ba89d1178de).html.
Texte intégralRésumé :
The standard model of particle physics is the most precisely verified scientific theory in the history of mankind. However, extended theories are already in place, ready to supersede the standard model should it fail to describe any new physics that may be observed in the next generation of high energy particle accelerators. One such minimal extension is the Two Higgs Doublet Model (2HDM). However, the appearance of additional symmetries to those of the gauge symmetries in the 2HDM can have consequences for the cosmological viability of the model, with the possibility for non-trivial topological defects forming during spontaneous symmetry breaking phase transitions.In this research we perform a systematic study of six accidental Higgs Family and CP symmetries that can occur in the 2HDM potential, by introducing and utilizing our Majorana scalar-field formalism. General sufficient conditions for convexity and stability of the scalar potential are derived and analytical solutions for two non-zero neutral vacuum expectation values of the Higgs doublets for each of the six symmetries are presented, in terms of the parameters of the theory. We identify the topological defects associated with the spontaneous symmetry breaking of each symmetry by means of a homotopy-group analysis. We find the existence of domain walls from the breaking of Z2, CP1 and CP2 discrete symmetries, vortices in models with broken U(1)PQ and CP3 symmetries and a global monopole in the SO(3)HF-broken model. We study the associated topological defect solutions as functions of the potential parameters via gradient flow methods. We also consider the cosmological implications of the topological defects and are able to derive bounds on physical observables of the theory in order to avoid contradictions with the theoretical limits on topological defects. The application of our Majorana scalar-field formalism in studying more general scalar potentials that are not constrained by the U(1)Y hypercharge symmetry is discussed. In particular, the formalism may be used to properly identify seven previously hidden symmetries that may be manifest in a U(1)Y invariant scalar potential for particular choices of the model parameters.
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Peabody, Frank Gerald. "An investigation of high speed, thin steel rotor, annular, double sided, linear induction motors." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/29056.
Texte intégralRésumé :
The objective of this dissertation is to analyse the performance of a linear induction motor suitable to drive a circular saw blade. A selection of analytical methods available from the field of electrical machine theory was used to investigate the particular type of motor. The theoretical analysis is supported by an extensive experimental investigation.
Although LIMs have been designed, analyzed and applied in other applications, significant differences exist between those LIMs and the one used for the new application. These include: the annular shaped motor, the smaller air gap, and the rotor which is thin and made of steel. Because of these differences, the methods used by previous investigators were not sufficient to design the LIM required.
The theoretical analysis used a selection of methods described in the literature to quantify the effect of the rotor material, the end effect and the edge effect. New methods are described to analyse the effect of the annular shape, the normal forces on the rotor and the coil connection. In addition, a new consideration in the optimisation of these type of motors is described. An extensive experimental program was undertaken. Six different linear motors were constructed with output powers ranging from one to fifty kWatts. In addition, inverters, dynamometers, flux measurement apparatus, speed measurement, thrust measurement and friction measurement apparatus were designed and constructed. The effects on performance of slot harmonics, winding connections, the end effect and the edge effect were measured.
Several contributions to the field of electrical machine theory are presented. The first is a new annular disc motor resistivity correction factor. Second, is the analysis of the effects of poles in parallel versus in series in linear induction motors. Third, is the experimental comparison between odd and even pole designs. The fourth is a second optimum goodness consideration for LIMs, which had not previously been considered. The fifth is the analysis of the rotor/stator attractive force for magnetic rotor double sided motors and a description of the flux (crenelated flux) which causes the force. Finally, a criterion for when the re-entry effect may occur is presented.<br>Applied Science, Faculty of<br>Electrical and Computer Engineering, Department of<br>Graduate
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Cockerton, Simon. "High resolution double crystal X-ray diffractometry and topography of III-V semiconductor compounds." Thesis, Durham University, 1991. http://etheses.dur.ac.uk/6278/.
Texte intégralRésumé :
Double crystal diffractometry and topography are now routinely used in many laboratories for the inspection of epitaxially grown devices. However the trend towards thinner layers and more complex structures requires the continued development of novel approaches using these techniques. This thesis is concerned with the development of these approaches to study the structural uniformity of semiconductor materials. The uniformity of large single crystals of lithium niobate has been studied using synchrotron radiation and double crystal X-ray topography. This study has shown a variety of contrast features including low angle grain boundaries and non-uniform dislocation densities. The abruptness of an interface between a layer and the underlying substrate has been studied using glancing incidence asymmetric reflections. Comparisons to simulated structures revealed that a closer match was achieved by the inclusion of a highly mismatched interfacial layer. This study illustrates the need for careful comparison between experimental and simulated rocking curves as different structures may produce very similar rocking curves. A double crystal topographic study of a AlGaAs laser structure revealed X-ray interference fringes. These are shown to be produced from the interaction of two simultaneously diffracting layers separated by a thin layer. Possible formation mechanisms have been discussed showing that these fringes are capable of revealing changes in the active layer at the atomic level. A novel approach has also been developed using synchrotron radiation to study the non-stoichiometry of GaAs. This approach uses the quasi-forbidden reflections which are present in III-V semiconductors due to the differences in the atomic scattering factors. This study has also discussed the behaviour of strong and weak reflections in the region of absorption edges and modelled their behaviour using the anomalous dispersion corrections of Cromer and Liberman.
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Rajec, Filip. "Two-Higgs-Doublet Models." Thesis, 2020. http://hdl.handle.net/2440/129649.
Texte intégralRésumé :
We look at global scans of the parameter space of Two-Higgs-Doublet Models (2HDMs). Our first study is a Bayesian analysis of the Yukawa Z₂-aligned 2HDMs: the type-I, type-II, type-X (lepton-specific) and type-Y (flipped) models. Incorporated into these analyses are the theoretical constraints: perturbativity checks, the stability of the potential and the unitarity of the scattering matrix (up to NLO). The generic potential couplings are run up to 1 TeV, stability and perturbativity are then rechecked at this upper bound. We also calculate loop corrections to the scalar masses and check that they do not grow too large. Next, we apply experimental constraints. These include Higgs signals and searches matched to the latest data from LEP, the Tevatron and the LHC. As well as fits onto the electroweak precision parameters and an array of flavour processes, notably the radiative B decays and the R(k) and R(*)(k) anomalies. Our second study is a frequentist analysis of the most general 2HDM (or type-III model), searching for limits on flavour changing quark decays. The most general 2HDM introduces flavour-changing currents (FCC). We apply a subset of the theoretical and the experimental bounds described above (at tree-level) and work with a restricted Yukawa sector. The restricted Yukawa sector allows FCC only between fermions and then only between the second and third generation. The flavour analysis focuses on the discrepancy in the B(0)(s)-meson mass splitting with the Standard Model (SM) and leads us to explore how this process may be better fit by a 2HDM.<br>Thesis (Ph.D.) -- University of Adelaide, School of Physical Sciences, 2020
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Chen, Yin-Chang, and 陳垠璋. "High-Power Matrerials for Electric Double layer Capacitors." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/63q3h2.
Texte intégralRésumé :
碩士<br>國立臺北科技大學<br>有機高分子研究所<br>102<br>In this study, the high surface area of activated meso-carbonemicro-beads and the carbon nanotube for use as modern composite supercapacitor electrodes. The activated mesocarbonemicrobeads will be porous in internal and external part for high performance electrode materials.
The aMCMB electrode has a high energy storage capacity. This capacitance of electrode is 350 F g-1 under current is 0.02A g-1. The capacitance of electrode will decrease to 155 F g-1 under current is 0.6A g-1. The study was decreased transfer path of internal ion and raise particle touch for power output of supercapacitor and high rate charge-discharge ability. This capacitance of electrode is 372 F g-1 under current is 0.02A g-1. The capacitance of electrode will decrease to 153 F g-1 under current is 0.6A g-1. The CNTs was added to milling process for raising electron transport and inter-granular pore. This capacitance of electrode is 292 F g-1 under current is 0.02A g-1. The capacitance of electrode will decrease to 177 F g-1 under current is 0.6A g-1.
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MARTELLA, Francesca. "Model-based double clustering for high dimensional data." Doctoral thesis, 2007. http://hdl.handle.net/11573/443513.
Texte intégral
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Lin, Po-Chang, and 林柏彰. "High Power Amplifier Design with Double-Emitter Layout at high frequencies." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/3n4m6h.
Texte intégralRésumé :
碩士<br>國立臺北科技大學<br>電腦與通訊研究所<br>102<br>In nowadays Wireless communications industry, the development of WLAN hardware is heading to major ways: “Faster transmission speed and, longer transmission distance”.
There are many versions/ protocols for IEEE 802.11 series standard, such as IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, IEEE 802.11n, and IEEE 802.11ac. In accordance with the requirement of these wireless communications system, the Integrated Circuit (IC) must provide excellent linearity under high-frequency & high output power. Based on this criterion, the elements of Ⅲ-Ⅴgroup’s microwave components, for example, Bipolar HBT and PHEMT just can meet the ideal wireless communications system’s requirement. HBT offers the advantages of high output power, good linearity, high cutoff frequency and low power-consumption. My Thesis adopts GaAs process of AWSC Foundry’s high-frequency power amplifier circuit and aim to the applications of IEEE802.11b/g/n PA. Beside to discover the RF theory and circuit design concept, I also use diversified layout techniques to eliminate wafer die-size. By these methods I can achieve of high power-output requirement as well as decrease more layout dimension, thus, save the total cost.
In summary, by this research of my Thesis, my design of high-power PA circuit complies IEEE 802.11b/g/n bandwidth regulation, which can generate 32dBm Pout at 2.4~2.5GHz by WiFi 802.11b modulation or 28dBm Pout by WiFi 802.11g/n modulation. And at Femtocell application, that can get 26dBm Pout at 2110~2170MHz, 24dBm Pout at 1805~1880MHz, 24dBm Pout at 1880~1920MHz, 25dBm Pout at 1930~1990MH, and 25dBm Pout at 2010~2025MHz.
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Chao, Kuan-Hua, and 趙冠驊. "High Linearity Enhancement-Mode Double-Channel AlGaN/GaN HEMTs." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/94888739604069885591.
Texte intégralRésumé :
碩士<br>國立雲林科技大學<br>電子工程系<br>103<br>The GaN material of III-V compounds has the excellent properties of material such as high breakdown voltage, high thermal conductivity, small permittivity and high cut-off frequency. It always has been operated in high power, high temperature and high frequency circuits because of the excellent characteristics of carrier transmission of AlGaN/GaN high electron mobility transistors (HEMTs). In the applications of communication transmission, linearity of device has effect in the degree of distortion of signal. Therefore, linearity is an important factor of device quality.
However, in the condition of zero bias that two-dimensional electron gas (2DEG) always exists because of the own properties of AlGaN/GaN HEMTs. Therefore, we have to exert a negative bias to close the device because of the device is depletion-mode. It is a drawback in the applications of power electronic devices so the circuit design is more complicate. Therefore, for reducing the cost of circuit design and the wasting of resources that how to design the enhancement-mode GaN material transistor is an important issue.
In this thesis, Sentaurus TCAD is used to simulate device characteristics of AlGaN/GaN HEMTs. First, we will introduce physical models and simulate the electrical characteristics of AlGaN/GaN HEMTs, in which the physical parameters will be calibrated so that the simulation results matches the measured data from a reference data. This process ensures the accuracy of the subsequent simulation work. Next, we will rebuilt our device in to a double-channel structure which’s basic design consult to a reference that has double AlGaN/GaN heterojunctions. After that we will compare the property of composite structure before we have a device which has a flat and wide transconductance peak after we modulate the variation and location of twin transconductance peaks of double-channel AlGaN/GaN HEMTs. The linearity is improved. Last, we use recessed-gate and changing the thick of material layer with partially p-type doping which’s location is under gate that make the depletion-mode device turning into enhancement-mode. Thus we successfully design an enhancement-mode double-channel AlGaN/GaN HEMT which has high linearity.