Dissertations / Theses on the topic 'Resonant'
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1
Fernandes, Ricardo Dias. "Resonant wireless power transmission based on resonant electrical coupling." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/16284.
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Doutoramento em Engenharia EletrotécnicaContained in this document are theoretical and experimental results related to the feasibility of resonant electrical coupling as a method of wirelessly transferring power across non-negligible distances. As shown, resonant electrical coupling is remarkably similar to resonant magnetic coupling in several aspects. However, while resonant magnetic coupling is currently a method of wirelessly transferring power with a very strong presence in the literature, resonant electrical coupling is not. The lack of material related to resonant electrical coupling, together with the potential of achieving a balanced trade-off between critical features such as efficiency, distance, simplicity, size and power transfer capability, were the main motivations for considering this specific topic. The possibility of constructively combining resonant electrical coupling and resonant magnetic coupling is also addressed. A review of the state of the art of wireless power, not only in terms of scientific publications but also in terms of market adoption and international standards, is included in this document.
Contidos neste documento estão resultados teóricos e experimentais relacionados com a viabilidade do uso de acoplamento elétrico ressonante como um método de transferência de energia sem fios através de distâncias não negligenciáveis. Conforme mostrado, o acoplamento elétrico ressonante é notavelmente semelhante ao acoplamento magnético ressonante em vários aspetos. No entanto, enquanto que o acoplamento magnético ressonante é atualmente um método de transferência de energia sem fios com uma presença muito forte na literatura, o acoplamento elétrico ressonante não é. A ausência de material relacionado com acoplamento elétrico ressonante, em conjunto com o potencial de atingir um compromisso equilibrado entre características críticas, tais como eficiência, distância, simplicidade, tamanho e capacidade de transferência de potência, foram as principais motivações para considerar este tóptico específico. A possibilidade de combinar de forma construtiva acoplamento elétrico ressonante e acoplamento magnético ressonante é também abordada. Uma revisão do estado da arte da transferência de energia sem fios, não só em termos de publicações científicas, mas também em termos de adoção do mercado e normas internacionais, é incluída neste documento.
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Szabo, Adrian. "The modelling of quasi-resonant and multi-resonant boost converters." Thesis, Nottingham Trent University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245100.
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Allcock, S. C. "Resonant particle spectroscopy." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379878.
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Naylon, Alexander. "Microwave resonant sensors." Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/15525/.
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Microwave resonant sensors use the spectral characterisation of a resonator to make high sensitivity measurements of material electromagnetic properties at GHz frequencies. They have been applied to a wide range of industrial and scientific measurements, and used to study a diversity of physical phenomena. Recently, a number of challenging dynamic applications have been developed that require very high speed and high performance, such as kinetic inductance detectors and scanning microwave microscopes. Others, such as sensors for miniaturised fluidic systems and non-invasive blood glucose sensors, also require low system cost and small footprint. This thesis investigates new and improved techniques for implementing microwave resonant sensor systems, aiming to enhance their suitability for such demanding tasks. This was achieved through several original contributions: new insights into coupling, dynamics, and statistical properties of sensors; a hardware implementation of a realtime multitone readout system; and the development of efficient signal processing algorithms for the extraction of sensor measurements from resonator response data. The performance of this improved sensor system was verified through a number of novel measurements, achieving a higher sampling rate than the best available technology yet with equivalent accuracy and precision. At the same time, these experiments revealed unforeseen applications in liquid metrology and precision microwave heating of miniature flow systems.
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Izham, Zaki. "Resonant MEMS magnetometer." Thesis, University of Birmingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436751.
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Kean, Richard David Valentine. "The resonant room." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/12864.
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This thesis looks at aural string installation as a medium and uses it to implement research within an Australian context. The title of this thesis, The Resonant Room, implies an intertextual strategy in developing this research that is situated within the ethos of aural string installation. Aural string installation as a medium is especially particular to several artists who live and work in Australia and the Netherlands, respectively. While this thesis does explore the work of all known aural string artists, its concern follows this into an intertextual account of the main themes inherent to aural string installation that are then applied to the specific context of Sydney, Australia. This strategy is undertaken through research that also entails making art with a reflective and speculative practice within the context in which it is made. This thesis then looks at strategies of experiential participation with aural string installation as a speculative critical and observational practice that concerns itself with both human artifice and Nature within the context of Sydney as a post-Fordist post-colonial country.
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Feifel, Raimund. "Resonant and Non-Resonant Electron Spectroscopy of Free Molecules and Free Clusters." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://publications.uu.se/theses/91-554-5566-2/.
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Rowe, David James. "Microfluidic microwave resonant sensors." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/39364/.
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Matter can be identified by its interaction with electromagnetic fields. This can be described by its dielectric and magnetic properties, which typically vary with respect to frequency in the microwave region. Microwave-frequency spectroscopy is capable of making non-contact, non-destructive, non-invasive and label-free measurements with respect to time. It can be used to characterise all states of matter and combinations thereof, such as colloids and microparticulate suspensions. Sensors based upon this technology therefore have great potential for (bio)chemical and industrial point-of-sampling applications where existing measurement techniques are insufficiently portable, low-cost or sensitive. Microfluidics is the manipulation of fluids within microscale geometries. This gives rise to phenomena not observed at the macroscale that can be exploited to achieve enhanced control of fluid flow. This means that microfluidic techniques can be used to perform complex chemistry in a completely sealed environment with minimal reagent consumption. Hence, microfluidics offers an ideal sample interfacing method for a microwave-frequency sensor. This work is concerned with developing novel, low-cost and highly sensitive probes that be easily integrated into a microfluidic device for performing on-chip sample preparation and diagnostics for generic (bio)chemical and industrial point-of-sampling applications. To this end, several novel microwave resonant structures were designed, optimised and integrated into microfluidic devices in order to characterise a variety of liquid-phase samples.
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Panov, Vasil. "LLC resonant converter modelling." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46521.
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Many of today's power converters use pulse-width modulation(PWM) techniques to regulate the circulating currents and voltages. A significant problem with most dc-dc converters is the increased power loss during switching. These devices typically operate in hard-switching mode which results in switching losses. Resonant converters have been used to minimize or even eliminate this problem.
Although LLC resonant converters have shown significant gains in terms of efficiency, their modeling is still a challenge. LLC converters are designed to function in a specific mode and region of operation. It has been difficult to design a stable and robust controller with consistent bandwidth and disturbance rejection for every application. The complexity of the control design is magnified when the LLC converters are controlled using embedded digital control techniques. Recent developments in micro-controllers, including processing speed, power, and memory management, make possible the use of innovative non-linear or adaptive control algorithms, in order to produce high performance LLC circuits. Accurate modeling of the hardware is the key to an effective solution.
This thesis presents several modeling techniques of the LLC resonant converter. Previous research is discussed and relevant techniques are used as reference for deriving the models presented here. A new approach will be used to describe the characteristics of the LLC within the operating region. This approach is derived using the method of Least Squares of errors. The method estimates the coefficients of the plant transfer function, which then help to calculate control coefficients in the instantaneous operating condition of the LLC resonant power converter.
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Becker, Matthew E. (Matthew Erin). "Resonant transmission line drivers." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/81519.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.Includes bibliographical references (leaves 71-72).
by Matthew E. Becker.
Ph.D.
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Dai, Chaobo. "A non-resonantly coupled parallel resonant converter for residential renewable energy conversion." Thesis, University of Birmingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433433.
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After the review of single-phase converter topologies and detailed examination of several candidates, a non-resonantly coupled parallel resonant DCIDC converter is identified as being the most appropriate high frequency linked topology. The steady-state characteristics of the chosen converter with both variable frequency and phase shift control have been examined using state-plane analysis. These theoretical predictions are confirmed with time-domain simulation and comprehensive measurements from a 3.0 kVA prototype. The power losses resulted from real devices and components account for the discrepancies. Hybrid control has been employed for stand-alone applications. By contrast, phase-shift control only at a reduced switching frequency provides better output performance and higher conversion efficiency. Under light loads, a look-up correction table has been developed to improve the output performance further. The prototype efficiency is measured to be 94% under full load. Integral compensator and phase shift control only have been utilized for grid-connected applications. A damping resistor has been added to damp the resonant oscillation of the output filter. Similarly, a correction table is introduced under light load. An additional compensator, increased DC gains and phase margin compensation have been introduced to improve the output performance further. The impact of the grid-connected converter on the grid voltage is also examined.
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Jovanović, Milan Miodrag. "High-frequency off-line power conversion using quasi-resonant and multi-resonant techniques." Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/53542.
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Three recently-proposed power conversion technologies, the zero-current-switching (ZCS) and zero-voltage-switching (ZVS) quasi-resonant techniques, and the zero-voltage-switching multi-resonant technique, are evaluated for high-frequency, off-line applications. The study is performed with emphasis on the conversion-frequency range, efficiency, load range, input-voltage range, output power, dynamic response, and power density.
A comprehensive dc analysis of the half-wave and full-wave, half-bridge zero-current-switched quasi-resonant converters (QRCs) is presented. Design procedures for closed-loop design of the converters are also derived. The procedures are used to design and fabricate half-wave and full-wave converters operating in the low-megahertz range and experimentally assess their suitability for high-frequency, off-line power conversion.
The zero-voltage-switching technique is employed to further increase the conversion frequency. First, the half-bridge zero-voltage-switched quasi-resonant converter is analyzed and the trade-offs between its frequency range, load range, and efficiency are examined in detail. The multi-resonant-switch concept is applied to this converter to improve its characteristics, primarily its load range.
A complete dc analysis of the zero-voltage-switched multi-resonant converter (MRC) is given and the dc voltage-conversion-ratio characteristics are derived. A graphic design procedure for the converter is established and is used to build an experimental 100 W, off-line converter operating in the frequency range of 2 MHz to 8 MHz.
Finally, a comprehensive comparison of the QRCs and MRCs is performed and conditions where their applications appears most desirable are defined.Ph. D.
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Chan, David. "A normal form approach to non-resonant and resonant Hopf bifurcation from relative equilibria." Thesis, University of Surrey, 2006. http://epubs.surrey.ac.uk/843715/.
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The main aim of this thesis has been to investigate the distinction between a nonresonant and resonant Hopf bifurcation from relative equilibria. Resonant and nonresonant Hopf bifurcations from relative equilibria posed in two spatial dimensions, in systems with Euclidean SE(2) symmetry, have been extensively studied in the context of spiral waves in a plane and are now well understood. We initially investigate Hopf bifurcations from relative equilibria posed in systems with compact S0(3) symmetry where S0(3) is the group of rotations in three dimensions/on a sphere. Unlike the SE(2) case the skew product equations cannot be solved directly and we use the normal form theory due to Fiedler and Turaev to simplify these systems. We show that the normal form theory resolves the nonresonant case, but not the resonant case. New methods developed in this thesis combined with the normal form theory resolves the resonant case. We find that the resonant Hopf bifurcation produces a motion which is strikingly different from the nonresonant case. By considering the geometric properties of the underlying relative equilibrium we give a definition of resonance directly related to the Hopf bifurcation phenomena. This yields conditions for the occurrence of a resonant Hopf bifurcation from a relative equilibrium in a system with general compact symmetry. By extending the approach used to resolve the S0(3) case we then solve the skew product equations for a general compact symmetry group. The specific case of a Hopf bifurcation from a relative equilibria with symmetry of an irregular dodecahedron is also considered. Furthermore we look at nonresonant and resonant Hopf Bifurcations from relative equilibria posed in a system with noncompact Euclidean symmetry in three spatial dimensions.
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Yang, Eric Xian-Qing. "Extended describing function method for small-signal modeling of resonant and multi-resonant converters." Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/40173.
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The extended describing function method is proposed as a systematic small-signal modeling approach to nonlinear switching circuits. This method offers significant simplification upon the previous work on using the multi-variable describing functions to treat the circuit nonlinearities. As an extension to the statespace averaging method, this modeling technique can incorporate any Fourier components for good model accuracy and provides continuous-time small-signal models for PWM topologies and various soft-switching resonant topologies.
The proposed method is demonstrated using four resonant topologies and two multi-resonant topologies. These circuits are strongly oscillatory, and thus they cannot be modeled by means of traditional averaging techniques. By employing the proposed modeling method, the dynamics of the resonant converters are analyzed with emphasis on the nonlinear interaction between the switching frequency and the circuit natural resonant frequency. Equivalent circuit models are provided for more convenience of practical designs. Small-signal analysis is also performed for two challenging multi-resonant topologies with complex structure and operation. All of the theoretical models are verified experimentally and the predictions are well supported by the measurement data up to the Nyquist frequency.Ph. D.
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Medina, Alfredo. "Low-Frequency Series Loaded Resonant Inverter Characterization." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1620.
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Modern power systems require multiple conversions between DC and AC to deliver power from renewable energy sources. Recent growth in DC loads result in increased system costs and reduced efficiency, due to redundant conversions. Advances in DC microgrid systems demonstrate superior performance by reducing conversion stages. The literature reveals practical DC microgrid systems composed of wind and solar power to replace existing fossil fuel technologies for residential consumers. Although higher efficiencies are achieved, some household appliances require AC power; thus, the need for highly efficient DC to AC converters is imperative in establishing DC microgrid systems. Resonant inverter topologies exhibit zero current switching (ZCS); hence, eliminate switching losses leading to higher efficiencies in comparison to hard switched topologies.
Resonant inverters suffer severe limitations mainly attributed to a load dependent resonant frequency. Recent advancements in power electronics propose an electronically tunable inductor suited for low frequency applications [24], [25]; as a consequence, frequency stability in resonant inverters is achievable within a limited load range. This thesis characterizes the operational characteristics of a low-frequency series loaded resonant inverter using a manually tunable inductor to achieve frequency stability and determine feasibility of utilization. Simulation and hardware results demonstrate elimination of switching losses via ZCS; however, significant losses are observed in the resonant inductor which compromises overall system efficiency. Additionally, harmonic distortion severely impacts output power quality and limits practical applications.
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Brandefelt, Nicklas. "Resonant States in Negative Ions." Doctoral thesis, Stockholm : Univ, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-199.
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Zhang, Ke. "Resonant and secular orbital interactions." College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/7300.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.Thesis research directed by: Astronomy. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Gray, Jonathan William. "Resonant cavity light emitting diodes." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399518.
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Poolman, Rhys. "The resonant acousto-optic effect." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/20118/.
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This dissertation is theoretical investigation of the resonant acousto-optic effect in ionic crystals and thin metal foils. The optical properties of these types of materials, in the presence of coherent acoustic pump excitation, are numerically modelled and compared with analytical results. The resonant acousto-optic effect in bulk ionic materials is shown to be dependent on the coupling of a bulk acoustic wave to the TO-phonon component of a TO-phonon polariton. This requires that the material used is not only an ionic crystal but also has a strongly anharmonic interatomic potential. It is also demonstrated that the process “TO phonon ± one (two) transverse acoustic phonon(s)→ TO phonon” is responsible for the cubic (quartic) resonant acousto-optic effect. The role of acoustic intensity and frequency in the optical properties of CuCl and TlCl is considered. Higher order transitions are also investigated. It is shown that, in the ferroelectric material LiNbO3, both cubic and quartic scattering channels are sufficiently strong enough to consider the resonant acousto-optic effect associated with them on an equal footing. The coupling strength of both scattering channels is estimated to the nearest order of magnitude. The cubic coupling is found be σ3 = 5 meV and the quartic coupling strength is found to be σ4 = 0.3 meV both for the acoustic intensity Iac = 25 kWcm−2. The effect the phase difference between the two anharmonic terms has on the optical properties of LiNbO3 is then investigated. A tunable THz filter is proposed, based on the resonant acousto-optic effect in LiNbO3. A numerical method is developed to calculated the partial wave amplitudes and optical properties of metal foils with acoustically excited, propagating sinusoidally corrugated surfaces. It is then used on a system of a thin acoustically perturbed Au foil on a glass substrate. The effects of varying the angle of incidence, acoustic wavevector, corrugation amplitude and foil thickness are investigated. The numerical method is shown to remain stable even for strong coupling between the acoustic wave and surface plasmon polariton.
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Whitehead, Timothy David. "The design of resonant absorbers." Thesis, University of Canterbury. Mechanical Engineering, 2005. http://hdl.handle.net/10092/6627.
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The purpose of this project was to investigate the acoustic performance of a range of resonant absorbers as typically used in automotive applications. A literature review considering sources of exhaust noise, muffler types and components, sound measurement, and prediction techniques was undertaken. Test facilities were constructed that allowed testing of muffler systems with either an engine or a speaker as the source of excitation. This enabled measurements made with a speaker to be compared to those made with an engine, the latter including flow, temperature and pressure effects. A number of different muffler systems were tested and their acoustic performance predicted using a scattering matrix technique. Comparing measured and predicted results allowed assessment of the accuracy of the predictions, the performance of various muffler components and the reliability of measurements. The model adequately predicted muffler performance for all muffler systems tested apart from those containing Helmholtz resonators. This was attributed to pressure and flow effects not included in the model. Using the modelling procedure presented, muffler systems can be quickly designed and optimised.
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Chen, Haoning (William). "LLC Resonant Current Doubler Converter." Thesis, University of Canterbury. Electrical and Computer Engineering, 2013. http://hdl.handle.net/10092/8492.
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The telecommunications market is one of the large rapidly growing fields in today’s power supply industry due to the increasing demand for telecom distributed power supply (DPS) systems. The half-bridge LLC (Inductor-Inductor-Capacitor) resonant converter is currently the most attractive topology for the design and implementation of 24V/48V DC telecom power converters. The current doubler rectifier (CDR) converter topology was invented and described in the early 1950s which can offer the unique characteristic of halving the output voltage while doubling the output current compared to a standard rectifier. In this thesis, the current doubler converter topology with its unique characteristic is evaluated as a complementary solution to improve the LLC resonant converter performance, especially for the low output voltage and high output current telecommunication applications. A novel half-bridge LLC resonant current doubler converter (LLC-CDR) is proposed in this thesis which can offer several performance benefits compared to conventional LLC-standard rectifier design . The unique characteristics of the LLC-CDR topology can offer significant improvements by transformation of a 48V converter into a 24V converter with the same power density. This thesis introduces a new SPICE-based simulation model to analyse the operation of this novel LLC-CDR converter circuit design. This model can be used to define the critical component parameters for the LLC -CDR circuit output inductor values. It can also be used to predict the circuit overall performance under different load conditions. Both time-domain based transient simulation analysis and frequency-domain based AC analysis provided by this simulation model showed favourable results in comparison to bench measurement results on a prototype. The model
provides a valuable insight to reveal some of the unique characteristics of this LLC -CDR topology. It demonstrates a proof of concept that the conventional LLC resonant
converter can be easily redesigned for low voltage, high current applications by using the LLC-CDR topology without requiring a new design for the LLC resonant stage components and the power transformer. A new magnetic integration solution was proposed to significantly improve the overall performance in the LLC-CDR topology that had not been published before. The LLC-CDR converter hardware prototypes with two output inductors coupled and uncoupled configurations were extensively modelled, constructed and bench tested.Test results demonstrated the suitability of an integrated coupled inductors design for the novel LLC-CDR converter application. The integrated coupled inductors design can significantly improve the LLC-CDR converter frequency-domain based AC simulation analysis results. In addition, these results also illustrate the potential benefit of how the magnetic integration design in general could reduce the magnetic component size, cost, and weight compared to the uncoupled inductors design. Finally, a hardware prototype circuit was constructed based on a commercial 1800 W single phase telecom power converter to verify the operation of this novel half bridge LLC-CDR topology. The converter prototype successfully operated at both no load and full load conditions with the nominal output voltage halved from 48VDC to 24VDC, and doubled the output current to match the same output power density. It also demonstrates that the efficiency of this novel half bridge LLC –CDR is 92% compares to 90% of EATON’s commercial 24VDC LLC resonant converter, which can fulfill the research goals.
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Leadbeater, Mark Levence. "Resonant tunnelling in semiconductor heterostructures." Thesis, University of Nottingham, 1990. http://eprints.nottingham.ac.uk/28733/.
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This thesis examines the electrical transport properties of a series of n-type GaAs/(AIGa)As double barrier resonant tunnelling devices with well widths between 50 angstrem and 2400 angstrem . The current-voltage characteristics show peak-to-valley ratios as high as 25:1 and as many as seventy resonances, with clear evidence of quantum interference effects at room temperature. The application of a high magnetic field parallel to the current flow produces magnetooscillations in the transport properties which allow the sheet charge density in the accumulation layer to be determined. The energy level in the well over a wide range of bias is obtained from analysis of thermal activation of resonant tunnelling. The contributions of elastic scattering and LO phonon emission to the valley current are investigated spectroscopically with a magnetic field and two phonon modes of the (AIGa)As barrier are observed. The buildup of space charge in the quantum well at resonance leads to intrinsic bistability in the current and differential capacitance of an asymmetric structure. Magnetoquantum oscillations due to a degenerate electron gas in the well are used to measure this charge buildup and demonstrate that the tunnelling process is truly sequential. The bistability is dramatically enhanced at high magnetic fields when the lowest energy Landau level of the well can accommodate a high electron density. In a strongly asymmetric sample, a new kind of bistability is observed where the off-resonant current exceeds the resonant current due to enhancement of charge buildup by intersubband scattering. The modulation of the scattering rate by a magnetic field produces periodic oscillations in the width of the bistability. In a magnetic field applied perpendicular to the current, the resonances are broadened as a consequence of the conservation of canonical momentum. The transition from electric to magnetic quantisation in wide wells is investigated and tunnelling into interfacial Landau levels is observed. The angular dependence of the resonances is used to probe conduction band anisotropy. In a tilted field, a completely new type of magneto-oscillations is observed.
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Narula, Rohit. "Resonant Raman scattering in graphene." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/118567.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, February 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 131-144).
In this thesis we encounter the formulation of a rigorous theory of resonant Raman scattering in graphene, the calculation of the so-obtained Raman matrix element K2f,1o for the 2D Raman mode with the full inclusion of the matrix elements and a physically appealing bridge between theory and experiment by eschewing the problematic ascription of graphene with a finite thickness. Finally, we elucidate an experimental study of the Raman D and G modes of graphene and highly-defected pencil graphite over the visible range of laser radiation. Marking a departure from the usual practice for light scattering in semiconductors of including only the dynamics of the electrons and holes separately, we show via fourth-order quantum mechanical perturbation theory using a Fock state basis that for resonant Raman scattering in graphene the processes to leading order are those that involve the simultaneous action of the electrons and holes. Such processes are indeed an order of magnitude stronger than those prevalent in the literature under the double resonance [1, 2, 3] moniker. We translate our perturbation theoretic analysis into simple rules for constructing Feynman diagrams for processes to leading order and we thereby enumerate the 2D and D modes. Using expressions for the terms to leading order obtained from our theoretical treatment we proceed to evaluate the Raman matrix element [4] for the Raman 2D mode by using state-of-the-art electronic [5] and iTO phonon dispersions [6] fit to ab initio GW calculations. For the first time in the literature we include the variation of the light-matter and electron-phonon interaction matrix elements calculated via an ab initio density functional theory (DFT) calculation under the local density approximation (LDA) for the electronic wavefunctions. Our results for the peak structure, position and intensity dependence are in excellent agreement with experiments [7, 8, 9, 10]. Strikingly, our results show that depending on the combination of the input (polarizer) and output (analyzer) polarization of the laser radiation, very different regions of the phonon dispersion are accessed. This has a direct impact on the dominant electronic transitions according to the pseudo-momentum conservation condition satisfied by the scattering of an electron by a phonon ki = kf + q. Using sample substitution [11] we deconvolve the highly wavelength dependent response of the spectrometer from the Raman spectra of graphene suspended on an SiO2 - Si substrate and graphite for the D and G modes in the visible range. We derive a model that considers graphene suspended on an arbitrary stratified medium while sidestepping its problematic ascription as an object of finite thickness and calculate the absolute Raman response of graphene (and graphite) via its explicitly frequency independent Raman matrix element [K'2f10]2 vs. laser frequency. For both graphene and graphite the [K'2f10]2 per graphene layer vs. laser frequency rises rapidly for the G mode and less so for the D mode over the visible range. We find a dispersion of the D mode position with laser frequency for both graphene and graphite of 41 cm-YeV and 35 cm-YeV respectively, in good agreement with Narula and Reich 131 assuming constant matrix elements, the observed intensity follows the joint density states of the electronic bands of graphene. Finally, we show the sensitivity of our calculation to the variation in thickness of the underlying SiO2 layer for graphene.
by Rohit Narula.
Ph. D.
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Jong, Owen. "Multi Resonant Switched-Capacitor Converter." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/88019.
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This thesis presents a novel Resonant Switched-Capacitor Converter with Multiple Resonant Frequencies, abbreviated as MRSCC for both high density and efficiency non-isolated large step-down Intermediate Bus Converter (IBC). Conventional Resonant Switched-Capacitor Converter (RSCC) proposed by Shoyama and its high voltage conversion ratio derivation such as Switched-Tank Converter (STC) by Jiang and li employ half sinusoidal-current charge transfer method between capacitors to achieve high efficiency and density operation by adding a small resonant inductor in series to pure switched-capacitor converter's (SCC) flying capacitor. By operating switching frequency to be the same as its resonant frequency, RSCC achieves zero-current turn off operation, however, this cause RSCC and its derivation suffer from component variation issue for high-volume adoption. Derived from RSCC, MRSCC adds additional high frequency resonant component, operates only during its dead-time, by adding small capacitor in parallel to RSCC's resonant inductor. By operating switching frequency higher than its main resonant frequency, MRSCC utilizes double chopped half-sinusoidal current charge transfer method between capacitors to further improve efficiency. In addition, operating switching frequency consistently higher than its resonant frequency, MRSCC provides high immunity towards component variation, making it and its derivation viable for high-volume adoption.MS
Following the recent trend, most internet services are moving towards cloud computing. Large data applications and growing popularity of cloud computing require hyperscale data centers and it will continue to grow rapidly in the next few years to keep up with the demand [4]. These cutting-edge data centers will require higher performance multi-core CPU and GPU installations which translates to higher power consumption. From 10MWatts of power, typical data centers deliver only half of this power to the computing load which includes processors, memory and drives. Unfortunately, the rest goes to losses in power conversion, distribution and cooling [5]. Industry members look into increasing backplane voltage from 12V to 48V in order to reduce distribution loss. This thesis proposes a novel Resonant Switched-Capacitor Converter using Multiple Resonant Frequencies to accommodate this increase of backplane voltage.
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Rickman, Edward E. "Study of resonant charge transfer." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/101461.
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Experimental measurements ol N₂ resonant charge transfer cross sections were performed. It was found that the energy of electrons used to produce the N₂⁺ ions is an important variable with respect to cross section. An examination of the experimental precision was performed and it was found that the precision of measurement was insufficient to determine the exact form of this relationship. The effect of ion energy (collisional energy) was too small to be seen.
Modulated detection was used to improve precision and permit measurement at high noise levels. A description of the apparatus is provided. Consideration of other systems and the suitability of their resonant charge transfer reactions for experimental investigation is discussed. Various theoretical models for estimation of cross section were examined.M.S.
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Breda, David Pedro. "Simulation of a resonant inverter." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/15931.
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Mestrado em Engenharia Electrónica e de TelecomunicaçõesMostly developed since the Industrial Revolution, the automation of systems and equipment around us is responsible for a technological progress and economic growth without precedents, but also by a relentless energy dependence. Currently, fossil fuels still tend to come as the main energy source, even in developed countries, due to the ease in its extraction and the mastery of the technology needed for its use. However, the perception of its ending availability, as well as the environmental impact of this practice has led to a growing energy production originated from renewable sources. Easy maintenance, coupled with the fact that they are virtually inexhaustible, makes the solar and wind energy very promising solutions. In this context, this work proposes to facilitate energy production from these sources. To this end, in this work the power inverter is studied, which is an equipment responsible for converting DC power available by solar or wind power in traditional AC power. Then it is discussed and designed a new architecture which, in addition to achieve a high energy e - ciency, has also the ability to adapt to the type of conversion desired by the user, namely if he wants to sell electricity to the power grid, be independent of it or bet on a self consumption system. In order to achieve the promised energy e ciency, the projected inverter uses a resonant DC-DC converter, whose architecture signi cantly decreases the energy dissipated in the conversion, allowing a higher power density. The adaptability of the equipment is provided by an adaptive control algorithm, responsible for assessing its behavior on every iteration and making the necessary changes to achieve maximum stability throughout the process. To evaluate the functioning of the proposed architecture, a simulation is presented using the PLECS simulation software.
Desenvolvida maioritariamente a partir da Revolução Industrial, a automatização dos sistemas e equipamentos que nos rodeiam e responsável por um progresso tecnológico e crescimento económico sem precedentes, mas também por uma incessante dependência energética. Atualmente, combustíveis fosseis ainda tendem a surgir com principal fonte de energia, mesmo em países desenvolvidos, devido a facilidade na sua extração e domínio da tecnologia necessária a sua utilização. No entanto, a perceção quer da sua findável disponibilidade, quer do impacto ambiental desta pratica, tem levado a uma crescente produção de energia proveniente de fontes renováveis. A sua fácil manutenção, aliada ao facto de serem praticamente inesgotáveis, faz das energias solar e eólica uma solução muito promissora. Neste contexto, esta dissertação propõe facilitar a produção de energia proveniente destas fontes. Assim, neste trabalho são estudados os inversores de potencia, equipamentos responsáveis por converter energia DC disponibilizada por uma fonte solar ou eólica em energia AC tradicional. Seguidamente e discutida e projetada uma nova arquitetura que, para al em de conseguir um alto rendimento energético, tem também a capacidade de se adaptar face ao tipo de conversão pretendida pelo utilizador, caso este queira vender energia a rede elétrica, ser independente desta ou apostar num sistema de auto consumo. Para alcançar o alto rendimento energético prometido, o inversor projetado faz uso de um conversor DC-DC ressonante, cuja arquitetura diminui consideravelmente a energia dissipada na conversão, permitindo assim uma maior densidade de potencia. A versatilidade do equipamento e disponibilizada por um algoritmo de controlo adaptativo, responsável por avaliar o comportamento deste a cada iteração e fazer as alterações necessárias para alcançar a máxima estabilidade ao longo de todo o processo. Para uma avaliação do funcionamento da arquitetura proposta, apresenta-se a simulação da mesma utilizando o software de simulação PLECS.
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Tewordt, Matthias Ludwig. "Resonant tunnelling in quantum dots." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260415.
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Pathak, Shantanu. "Resonant optical waveguide biosensor characterization." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3792.
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Thesis (M.S.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains viii, 109 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 107-109).
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Triggs, Graham J. "Resonant grating surfaces for biosensing." Thesis, University of York, 2016. http://etheses.whiterose.ac.uk/13210/.
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Optical biosensors make up a valuable toolkit for label-free biosensing. This thesis presents a detailed study on resonant grating surfaces for biosensing. The focus is on silicon nitride gratings, which exhibit a guided-mode resonance that is highly sensitive to refractive index variations in the vicinity of the grating. A sensitivity of 143 nm/RIU (refractive index units) is measured, leading to a detection limit of 2.4×10−4 RIU. This performance is shown to be sufficient for the detection of biomolecular binding down to ng/mL concentrations. With out-of-plane excitation, these gratings can be used as a sensing surface, enabling a spatially-resolved measurement of variations in refractive index; resonance imaging. The minimum detection distance (sensing depth) is measured to be 183 nm away from the grat- ing, while the spatial resolution of resonance imaging is found to be asymmetric: 2 μm parallel to, or 6 μm perpendicular to the gratings. Using a novel approach of fabricating a resolution test pattern on top of the grating, the relationship between resolution and index contrast is studied - an important question in the context of biosensing - where it is found to decrease with index contrast. All experimental results are supplemented with theoretical and computational models. The resonant gratings are then extensively applied to the study of biofilm development, cellular imaging, and the imaging of cellular secretion. Finally, a miniaturised biosensor is demonstrated, based on a chirped resonant grating. By tuning the resonance wavelength spatially on the chip, the resonance information is directly translated into spatial informa- tion. Instrument read-out requires just a monochromatic light source and a simple CCD camera, resulting in a final device that is inexpensive, compact, robust and can be remotely operated. Performance is proven with successful detection of biomolecular binding.
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Chalmers, Luke. "Locally resonant periodic acoustic media." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/7120.
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Phononic crystals are composite media, with two different elastic materials modulated in a periodic fashion. The two-dimensional system under study is comprised of an array of cylindrical tubes arranged in a square Bravais lattice. The propagation of a time-harmonic acoustic Bloch waves is investigated experimentally and the findings compared with those obtained from the finite element method. The band structure, that is a well-known characteristic of Bloch wave dispersion, is also determined. This demonstrates the existence of band gaps of forbidden transmission at certain frequency ranges. These arise due to the interference when the wavelength of the incident wave is comparable to the periodic spacing of the modulated media. A second phononic crystal with slotted steel tubes is also studied. The opening in the tube permitting air to flow to the internal cavity, and constituting a Helmholtz resonator. The band structure of such a structure possesses additional band gaps, which arise due to the excitation of the resonators. Furthermore, it has recently been shown that periodically distributed Helmholtz resonator structures, can exhibit negative refraction phenomena. Using the transmission line technique, as outlined by Y.Cheng et al. we demonstrate this behaviour for our experimental system. It is shown that, at certain frequency ranges, the locally resonant phononic crystal exhibits negative effective density and bulk modulus, the two conditions required to obtain a negative index of refraction.
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Masuda, Ryo. "Dependence of incoherent nuclear resonant scattering of synchrotron radiation on the number of resonant nuclei." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136766.
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Lintz, William A. "Electromagnetic resonances of metallic bodies." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA333440.
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Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, June 1997.Thesis advisors, Richard W. Adler, Jovan E. Lebaric. Includes bibliographical references (p. 45). Also available online.
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Flynn, Kevin Joseph. "Defect analysis using resonant ultrasound spectroscopy." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2348.
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Greaves, Thomas. "Studies of some acoustic resonant systems." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/25885.
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The resonant frequency shift, δf, of an acoustic resonator by a small spheroidal obstacle is calculated. For a spheroid whose dimensions are small compared to the wavelength of the sound waves it is shown that δf can be expressed in terms of the spheroid geometry and the structure of the acoustic modes in the immediate vicinity of the spheroid, whereas in the usual method of calculating δf one needs to know the detailed structure of the normal modes of the resonator. Interest in the topic is motivated by current studies of the acoustical levitation of materials in microgravity environements. The significance of the results for the study of the acoustical levitation of liquid droplets in neutral buoyancy environments is discussed.
With a view to applying these results, the mechanical properties of an electro-acoustic transducer with an impedance well matched to liquids are measured. The transducer consists of neoprene sandwiched between two conducting plates. The displacement of the transducer under different driving conditions has been measured usng an interferometric technique with angstrom sensitivity. An unusual feature of the interferometer is the degree of sensitivity achievable without vibration isolation mountings or temperature control of the environment. Using these measurements a qualitative model is developed to explain the unexpected aspects of the dynamical behavior of the transducer. The thesis concludes with-suggestions for further development of the transducer system.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Ali, Mohammod. "Analyses of self-resonant bent antennas." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ32701.pdf.
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Eriksson, Tommy. "Resonant Waves in the Terrestrial Magnetosphere." Licentiate thesis, Stockholm : Alfvén laboratory, Royal institute of technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-400.
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Leichle, Thierry C. "A micromachined resonant magnetic field sensor." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/13833.
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Giltrow, M. "Phonon study of vertical resonant structures." Thesis, Lancaster University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337346.
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Petch, Jason Charles. "Resonant four-wave mixing in krypton." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243502.
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Saeed, Kashif. "Microwave Materials Characterisation Planar Resonant Sensors." Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494259.
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Hutchinson, A. "Acoustoelectric interactions in resonant tunnelling structures." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604843.
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This thesis presents a novel device architecture allowing the monolithic integration of SAWs and semiconductors, which compensates for the inherent weakness of piezoelectric coupling in GaAs by relying on a strong non-local interaction mechanism. A special double-barrier quantum well RTS is designed so that large vertical currents can be sensitivity triggered by a small potential near the surface of the structure, such as the potential associated with a SAW. When a SAW beam is incident on the RTS mesa, the peaks ( and valleys) of the SAW electric field change the potential across the quantum well, resulting in local increases (and decreases) of the current through the structure. With the appropriate device design, the net effect of the SAW integrated over the entire RTS mesa will induce a microwave current in the receiving circuit connected to the RTS emitter. The basic linear and nonlinear properties of the microwave response have been investigated. Simple phenomenological models taking into account the spatial distribution of the SAW electric field and the nonlocality of the RTS conductivity have demonstrated good agreement with experimental results. The effect of varying the RTS layer structure on both the dc characteristics and the microwave response has been investigated theoretically, and experiments once again support the predictions. A process for non-annealed Ohmic contact to the RTS emitter has been optimized, in which Al is grown in situ on highly-doped GaAs incorporating several layers of δ-doping near the surface. The use of this contact method helps to eliminate the extrinsic instability observed in the negative differential resistance region of early devices. Finally, possible applications of the interaction are discussed, including a proposal for the parametric generation of very high frequency SAWs.
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Bell, Simon Colin. "High-voltage partial-core resonant transformers." Thesis, University of Canterbury. Electrical and Computer Engineering, 2008. http://hdl.handle.net/10092/2161.
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This thesis first describes the reverse method of transformer design. An existing magnetic model for full-core shell-type transformers, based on circuit theory, is summarised. A magneto-static finite element model is introduced and two sample transformers are analysed. The magnetic model based on finite element analysis is shown to be more accurate than the model based on circuit theory.
Partial-core resonant transformers are then introduced and their characteristics are explained using an equivalent circuit model. A method of measuring the winding inductances under resonant operation is developed and used to investigate the characteristics of two different tuning methods. A finite element model of the partial-core resonant transformer is developed by adopting the model for full-core shell-type transformers.
The model results accurately match the measured inductance variation characteristics of three sample transformers and predict the onset of core saturation in both axial-offset and centre-gap arrangements. A new design of partial-core resonant transformer is arrived at, having an alternative core and winding layout, as well as multiple winding taps. The finite element model is extended to accommodate the new design and a framework of analysis tools is developed. A general design methodology for partial-core resonant transformers with fixed inductance is developed. A multiple design method is applied to obtain an optimal design for a given set of specifications and restrictions. The design methodology is then extended to devices with variable inductance.
Three design examples of partial-core resonant transformers with variable inductance are presented. In the first two design examples, existing devices are replaced. The new transformer designs are significantly lighter and the saturation effects are removed. The third design example is a kitset for high-voltage testing, with the capability to test any hydro-generator stator in New Zealand. The kitset is built and tested in the laboratory, demonstrating design capability. Other significant test results, for which no models have yet been developed, are also presented. Heating effects in the core are reduced by adopting an alternative core construction method, where the laminations are stacked radially, rather than in the usual parallel direction. The new kitset is yet to be used in the field.
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Theisen, Michael John. "Polarimetric Properties of Optically Resonant Nanostructures." Thesis, University of Rochester, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3686567.
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Optically resonant nanostructures have been incorporated into a variety of devices used in a number of different fields. In this thesis, we explore optically resonant nanostructures in two forms. First we investigate a relatively new material, gallium implanted silicon (Si:Ga). We cover the fabrication process and experimentally find the optical properties as a function of both dose and wavelength. We then use the properties of this new material to create suspended arrays of Si:Ga nanowires, and determine their optical characteristics. In the second part of this thesis, we use more conventional materials and fabrication procedures to investigate the phase effects of guided mode resonators. We look at the spectral phase effects for a grating coupled silicon-on-insulator based guided mode resonator. We also look the angular phase effects of a surface plasmon polariton based guided mode resonator, comparing experimental results to theory calculated with rigorous coupled wave analysis for both cases. In addition, the guided mode resonance is modeled as a Fano resonance to gain insight into the functional form of the phase. Knowing the phase response of guided mode resonances may allow the creation of guided mode resonance based devices with higher sensitivity than traditional reflectance based devices.
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Nguyen, Henry Q. "Steady state analysis of resonant converters." Honors in the Major Thesis, University of Central Florida, 1993. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/118.
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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.Bachelors
Engineering
Electrical Engineering
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Phillips, Allan T. "Resonant terahertz absorption using metamaterial structures." Thesis, Monterey, California. Naval Postgraduate School, 2012. http://hdl.handle.net/10945/27888.
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The Sensor Research Lab at the Naval Postgraduate School is developing a real-time THz imaging camera. Vital to its design is the metamaterial absorbing layer (metafilm) within each pixel that allows for THz absorption. While there are numerous applications in the THz region, sensors and sources for THz energy have much room for improvement. The use of metamaterial technology for the purpose of a THz sensor has the potential to reduce costs while greatly improving sensitivity performance. The Sensor Research Lab has fabricated metafilms capable of near 100 percent absorption. In this research project, absorption characteristics of a set of metamaterials were measured using Fourier transform THz spectroscopy and modeled using an RLC circuit. The model provides a good description of the absorption characteristics and should assist in better understanding of the electromagnetic interactions within the metafilm.
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Sung, Wang-Kyung. "High-frequency tri-axial resonant gyroscopes." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/52936.
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This dissertation reports on the design and implementation of a high-frequency, tri-axial capacitive resonant gyroscopes integrated on a single chip. The components that construct tri-axial rotation sensing consist of a yaw, a pitch and a roll device. The yaw-rate gyroscope has a wide bandwidth and a large full-scale range, and operates at a mode-matched condition with DC polarization voltage of 10V without frequency tuning requirement. The large bandwidth of 3kHz and expected full-scale range over 30,000˚/sec make the device exhibit fast rate response for rapid motion sensing application. For the pitch-and-roll rate sensing, an in-plane drive-mode and two orthogonal out-of-plane sense-modes are employed. The rotation-rate sensing from lateral axes is performed by mode-matching the in-plane drive-mode with out-of-plane sense-modes to detect Coriolis-force induced deflection of the resonant mass. To compensate process variations and thickness deviations in the employed silicon-on-insulator (SOI) substrates, large electrostatic frequency tunings of both the drive and sense modes are realized. A revised high aspect ratio combined polysilicon and silicon (HARPSS) process is developed to resolve the Coriolis response that exists toward out-of-plane direction while drive-mode exists on in-plane, and tune individual frequencies with minimal interference to unintended modes. To conclude and overcome the performance limitation, design optimization of high-frequency tri-axial gyroscopes is suggested. Q-factor enhancement through reduction of thermoelastic damping (TED) and optimizations of physical dimensions are suggested for the yaw disk gyroscope. For the pitch-and-roll gyroscope, scaling property of physical dimension and its subsequent performance enhancement are analyzed.
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Fu, Colin Leong Chee. "Power-control design of resonant converters." Thesis, University of Warwick, 1999. http://wrap.warwick.ac.uk/4368/.
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Novel design techniques are presented for load-resonant and quasi-resonant converters for use in, for example, arc-welding and fan-load power supplies. Both converters are capable of very high switching frequency over a wide range of output power, with high efficiency and the presentation of near-unity power factor to the primary power supply. Previous work, by the author and his colleagues, has produced. a frequency-domain approach to produce circuit-designs for use in load-resonant converter applications. This design technique, although simple and straight-forward to understand, suffers by requiring some rather tedious trial-and-error algebraic and arithmetic manipulations albeit computer assisted. In this thesis, a systematic way of designing such circuits, based on Gr6bner Basis ideas, is explained, developed and compared with the previous best-practice design method. By employing the Gr6bner Basis techniques to synthesize electrical circuits, an entirely novel approach to the design of series-parallel load-resonant converter circuits is presented. This has led to the formulation of a new output-power control methodology in the design of the converters. These techniques produce output-power-control designs that have superior properties, compared with other established methods, in the sense of their simplicity, robustness and flexibility. It is found that the methodology can be further extended to alter any resonant circuits and, hence enables multilevel-output power to be controlled without involving complex control and advanced mathematical theories, while still preserving the desirable characteristics of resonant switching. The technique is, in fact, far more generally useful in the circuit-design/synthesis arena than the specific load-resonant-converter application for which it was developed. The novel technique used to vary the speed of an induction motor is found to be promising. Various test results are presented based on an experimental system.
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McDonnell, Paul. "Resonant tunnelling across double barrier structures." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285640.
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Wilkinson, Paul Bryan. "Quantum chaos in resonant tunnelling diodes." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363557.
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Turner, Thomas Stephen. "Optical studies of resonant tunnelling structures." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284112.
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