Дисертації з теми "Electron acoustic waves"
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Son, Seok-Kyun. "Electron transport by surface acoustic waves in an undoped system." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708763.
Повний текст джерелаMcEnaney, Kevin Bernard. "Magneto-absorption of surface acoustic waves by a 2-dimensional electron gas." Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293651.
Повний текст джерелаHou, Hangtian. "Low-dimensional electron transport and surface acoustic waves in GaAs and ZnO heterostructures." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/288235.
Повний текст джерелаEdlbauer, Hermann. "Electron-quantum-optics experiments at the single particle level." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAY027/document.
Повний текст джерелаIn the last 25 years there were several reports on quantum-optics-like experiments that were performed with electrons.The progress is this young field of research brought up original techniques to trap, displace and manipulate electrons in solid-state devices.These advances opened up new prospects to study fascinating quantum mechanical phenomena such as tunneling or entanglement with electrons.Due to the controllability that is demanded in possible implementations of quantum logic circuits, it is now a particularly appealing idea to perform electron quantum optics experiments with single flying electrons.In this thesis we address two related, but conceptually different, electron-quantum-optics experiments at the single-particle level.All of the experiments that were conducted in the course of this thesis were performed at cryogenic temperatures with Schottky-gate defined devices in AlGaAs/GaAs heterostructures.In a first experiment, we perform a Mach--Zehnder type electron interference experiment in the ballistic transport regime.Forming a large quantum dot in one of the interferometer branches, we study the phase shift in the wave function of a resonantly transmitted electron.In the course of our experimental investigations, we find signatures of a transmission behaviour which reflect the internal symmetries of the quantum dot eigenstates.Our measurements shed light on the long-standing question about a universal transmission phase behaviour in large quantum dots.We thus set an important milestone towards a comprehensive understanding of resonant transmission of single flying electrons through quantum dots.In a second experiment, we go beyond the ballistic transport regime.We employ surface acoustic waves to transport a single electron between surface-gate defined quantum dots of a tunnel-coupled circuit of transport channels.In this course, we develop two essential building blocks to partition and couple single flying electrons in such a sound-driven circuit.By exceeding a single-shot transfer efficiency of 99 %, we show that a sound-driven quantum electronic circuit is feasible on a large scale.Our results pave the way for the implementation of quantum logic operations with flying electron qubits that are surfing on a sound wave
Bertrand, Benoit. "Long-range transfer of spin information using individual electrons." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAY020/document.
Повний текст джерелаRecently a growing interest emerged towards the use of electron spins for information processing. The current developments range from the generation of spin polarized currents to the coherent manipulation of single electron spins in quantum dots, with applications in spintronics and quantum information processing respectively. The main objective of this thesis was to develop the equivalent of spintronics at the single electron level. For that purpose, we try to achieve the coherent transport of a single electron spin between distant quantum dots. This could be a promising means of interconnecting different nodes of a quantum nanoprocessor. The electron transfer is ensured by a surface acoustic wave (SAW) that induces dynamical quantum dots thanks to the material piezoelectricity. First, the injection of a single electron from a static to a dynamical quantum dot has been studied. It enables the control of single electron transfer with unity probability down to the nanosecond timescale, thanks to a fast engineering of the static confining potential. Next, we demonstrate the possibility to prepare a coherent spin superposition, using an isolated double quantum dot in a metastable position that is compatible with SAW-assisted electron transfer. This type of isolated dot systems offers more liberty in terms of control. Taking advantage of this feature, a new scheme for coherent spin manipulations has been implemented and proved to have reduced noise sensitivity. Finally, transfer of spin information encoded in one or two electrons has been achieved, with fidelities reaching 30%
Thorn, Adam Leslie. "Electron dynamics in surface acoustic wave devices." Thesis, University of Cambridge, 2009. https://www.repository.cam.ac.uk/handle/1810/224176.
Повний текст джерелаMcNeil, Robert Peter Gordon. "Surface acoustic wave quantum electronic devices." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610718.
Повний текст джерелаNash, Geoffrey Richard. "Surface acoustic wave investigations of low dimensional electron systems." Thesis, University of Bath, 1996. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320474.
Повний текст джерелаSchneble, Robert Jeffery. "Control of electrons for quantum information processing using surface acoustic waves." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613276.
Повний текст джерелаGiavaras, Georgios. "Electron interactions and quantum entanglement in surface acoustic wave structures." Thesis, Lancaster University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441115.
Повний текст джерелаSchuler, Leo Pius. "Wireless identification and sensing using surface acoustic wave devices." Thesis, University of Canterbury. Electrical Engineering, 2003. http://hdl.handle.net/10092/1081.
Повний текст джерелаRobinson, Andrew Malcolm. "Dynamics and noise in surface-acoustic-wave-based single-electron- transport devices." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620234.
Повний текст джерелаHole, Erik Lillebø. "Optical Fiber sensing of acoustic waves using overlapping FBGs." Thesis, Mittuniversitetet, Institutionen för elektronikkonstruktion, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-37779.
Повний текст джерелаFriedlander, Jeffrey B. "Wireless Strain Measurement with Surface Acoustic Wave Sensors." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306874020.
Повний текст джерелаGhafouri-Bakhsh, Shakour. "Interfacial electric phenomena and the thickness-shear mode acoustic wave sensor." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0031/NQ63820.pdf.
Повний текст джерелаVasiljevic, Milos. "Guided Wave Inspection of Pipes Using Electromagnetic Acoustic Transducers." Thesis, The University of Arizona, 2007. http://hdl.handle.net/10150/193355.
Повний текст джерелаDu, Xinpeng. "Laser-Ultrasonic Measurement of Single-Crystal Elastic Constants from Polycrystalline Samples by Measuring and Modeling Surface Acoustic Wave Velocities." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524177819455643.
Повний текст джерелаRoe, Austin R. "RESONANT ACOUSTIC WAVE ASSISTED SPIN-TRANSFER-TORQUE SWITCHING OF NANOMAGNETS." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/6029.
Повний текст джерелаKnapp, Marius [Verfasser], and Oliver [Akademischer Betreuer] Ambacher. "Graphene - from synthesis to the application as a virtually massless electrode material for bulk acoustic wave resonators." Freiburg : Universität, 2018. http://d-nb.info/1179694619/34.
Повний текст джерелаArapan, Lilia. "Thin Film Plate Acoustic Resonators for Frequency Control and Sensing Applications." Doctoral thesis, Uppsala universitet, Fasta tillståndets elektronik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-178592.
Повний текст джерелаPavlova, Anastasia. "Préparation et études des propriétés des films magnétiques nanostructures pour des applications en dispositifs magnéto-acoustiques et spintroniques." Thesis, Ecole centrale de Lille, 2014. http://www.theses.fr/2014ECLI0010/document.
Повний текст джерелаNowadays, structures based on ferromagnetic materials are largely used for different applications: random access magneto-resistive memories, magnetic sensors, and also new electronic components and spintronic devices. The general trend of modern electronic is the reduction of dimensions down to submicronic scales. Therefore, the magnetic nanostructures are of great interest and their methods of fabrication and properties largely studied.The main goal of this work is the preparation and experimental and theoretical research on properties of magnetic nanostructures for applications in magnetoresistive and photonic devices. The Scanning Probe Lithography (SPL) and Electron Beam Lithography (EBL) were used for the nanostructures fabrications. First steps were also achieved in fabrication of phononic cristals sensitive the magnetic field
Van, Duyne Scott A. "Digital filter applications to modeling wave propagation in springs, strings, membranes and acoustical space /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
Повний текст джерелаRocha, Gaso María Isabel. "Analysis, implementation and validation of a Love mode surface acoustic wave device for its application as sensor of biological processes in liquid media." Doctoral thesis, Editorial Universitat Politècnica de València, 2013. http://hdl.handle.net/10251/32492.
Повний текст джерелаIn the last two decades, different acoustic technologies for biosensors applications have emerged as promising alternatives to other better established detection technologies ¿ acoustic or optic ones- such as traditional Quartz Crystal Microbalance (QCM) and Surface Plasmon Resonance (SPR). The alternative acoustic technologies for in liquid measurements are reviewed in this manuscript. Surface Acoustic Wave (SAW) Love Mode or Love Wave (LW) sensors are determined to be the most promising and viable option to work with for achieving the main aim of this Thesis. Such aim is the development of a LW immunosensor for its comparison with the same application based on High Fundamental Frequency-QCM (HFF-QCM) sensors and under the same conditions. Consequently, the state-of-the-art of LW devices for biosensing is provided and a discussion about the current trends and future challenges of these sensors is presented. In order to start working with suitable LW devices, upto- date information regarding the design aspects, operation principles and modeling of such devices is gathered. Some design aspects are explored and tested to establish the design of the final LW device. Different simulations for modeling the chosen device behavior are carried out before its fabrication. Later, the device fabrication is described. Next, to start working with the fabricated device in liquid media, a flow cell is designed and implemented. In addition, an electronic characterization system, previously validated for QCM sensors, is adapted and tested for the fabricated LW device. As results, the adapted electronic characterization system is validated for LW devices mounted in the fabricated flow cell and, finally, a LW-based immunosensor for the determination of carbaryl pesticide was developed and compared with other immunosensor technologies.
Rocha Gaso, MI. (2013). Analysis, implementation and validation of a Love mode surface acoustic wave device for its application as sensor of biological processes in liquid media [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/32492
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Law, Yiu Kui. "Design and Testing of Off-The-Shelf Electronic Components for an Acoustic Emission Structural Health Monitoring System Using Piezoelectric Sensors." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/34477.
Повний текст джерелаMaster of Science
Ranciaro, Neto Adhemar. "Transporte eletrônico em sistemas de baixa dimensionalidade com interação elétron-fônon e campos elétricos." Universidade Federal de Alagoas, 2016. http://www.repositorio.ufal.br/handle/riufal/1459.
Повний текст джерелаNeste trabalho foi estudado o problema dinâmica de um elétron em dois sistemas unidimensionais distintos: (1) rede não harmônica com interação elétron-fônon e sob a ação de um campo elétrico estático aplicado paralelamente a ela e (2) rede harmônica com desordem diagonal não correlacionada, com interação elétron-fônon e sob a influência de ondas acústicas de superfície (SAW). Nos dois casos, foram utilizados formalismo quântico para o estudo do elétron e uma hamiltoniana clássica para as vibrações da cadeia. Além disso, o acoplamento do ente quântico com a rede foi descrito a partir da energia de transferência entre íons vizinhos, com aquela sendo dependente da distncia efetiva destes. Foi aplicado o método numérico de expansão truncada de Taylor para a evolução temporal da equação de Schrödinger dependente do tempo em ambos os casos, enquanto para a dinâmica das deformações foram empregados métodos distintos (Euler e diferenças finitas). Os resultados de (1) apontaram para a ocorrência de uma competição entre o acoplamento elétron-fônon e o campo elétrico. O primeiro promove um par elétron-soliton que se move ao longo da cadeia e o segundo aprisiona o elétron em torno de sua posição inicial criando oscilações semelhantes às de Bloch. No sistema (2), a associação entre SAW e a interação elétron-rede destroem o fenômeno da localização de Anderson permitindo o transporte de carga, mesmo em níveis altos de desordem. Os níiveis de precisão numérica são aceitáveis e os cálculos estão em consonância com os preceitos teóricos.
Bautze, Tobias. "Towards quantum optics experiments with single flying electrons in a solid state system." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENY059/document.
Повний текст джерелаThis thesis contains the fundamental study of nano-electronic systems at cryogenictemperatures. We made use of ballistic electrons in a two-dimensional electron gasin a GaAs/AlGaAs heterostructure to form a real two-path electronic interferometerand showed how the phase of the electrons and hence their quantum state can becontrolled by means of electrostatic gates. The device represents a promising candidateof a flying qubit. We developed a sophisticated numerical tight-binding model based onballistic quantum transport, which reproduces all experimental findings and allows togain profound knowledge about the subtle experimental features of this particular device.We proposed further measurements with this flying qubit system. With the ultimate goalof building a single electron flying qubit, we combined the single electron source that hasbeen developed in our lab prior to this manuscript with an electronic beam splitter. Theelectrons are injected from static quantum dots into a train of moving quantum dots.This moving potential landscape is induced in the piezoelectric substrate of GaAs bysurface acoustic waves from interdigial transducers. We studied and optimized all keycomponents, which are necessary to build a single electron beam splitter and built up areliable local fabrication process. The device is capable of studying electron interactionson the single electron level and can serve as a measurement platform for quantum opticsexperiments in electronic solid state systems. Finally, we developed a powerful toolcapable of calculating the potential landscapes of any surface gate geometry, which canbe used as a fast feedback optimization tool for device design and proposed an optimizedprototype for the single electron beam splitter
Pujol, Aurélien. "Modélisation et traitement du signal d'une cellule électroacoustique pulsée pour l'étude de la charge des diélectriques spatiaux." Thesis, Toulouse 3, 2021. http://www.theses.fr/2021TOU30004.
Повний текст джерелаThis thesis is in the context of the reliability of satellites subjected to a space environment. Indeed, satellites are made of various dielectric materials which may be charged by electrical particles (electrons and ions). The local accumulation of these particles is called space charge that tends to modify chemical, mechanical and electrical properties of dielectric materials. These modifications cause some physical phenomena, as electrostatic discharges (ESD), that may damage satellite elements and then render obsolete some of its functions. In order to avoid these kinds of scenarios, the National center for space study (CNES) and the "Laboratoire plasma et conversion d'énergie" (LAPLACE) seek to characterize dielectric materials employed in space environment using techniques to probe the charge in time and space. The PEA, or Pulsed Electro-Acoustic method, is one of these techniques. The objective of this thesis to optimize the signal processing of a PEA measurement bench in order to better estimate the time-space distribution of the charge inside a dielectric sample. To achieve this, an original method, based on an optimized PSpice model of the PEA measurement bench, has been developed to allow the characterization of a transfer function of the bench. Using a regularization technique, based on the Tikhonov's one, the results show that the recovery charge obtained from a calibration signal correspond fully to the applied experimental charge. This new signal processing developed during this thesis will allow to study samples: (i) that attenuate and disperse too much the acoustic waves; (ii) that are multilayer; (iii) for which the charges are localized near the irradiated surface; (iv) that are too thin (some tens of microns)
Silva, Ricardo Ezequiel da. "Acousto-optic modulation of optical reflection properties in fiber Bragg gratings and the application in fiber lasers." Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1805.
Повний текст джерелаEsta tese tem como objetivo investigar a interação de ondas acústicas e redes de Bragg (FBGs) em fibras ópticas convencionais e fibras de núcleo suspenso (SCFs), para avaliar a influência do projeto da fibra, da rede e do modulador, no aumento da eficiência de modulação, largura de banda e frequência. Inicialmente, a resposta em frequência e os modos acústicos de ressonância de um modulador acusto-óptico de baixa frequência (f < 1,2 MHz), são investigados numericamente usando o método dos elementos finitos. Posteriormente, também é investigada numericamente a interação de ondas acústicas longitudinais e FBGs em SCFs. Os parâmetros geométricos das fibras são variados e as propriedades da rede são simuladas por meio do método dos elementos finitos e o método da matriz de transferência. O estudo indica que os furos de ar que compõem a SCF causam uma redução significativa da quantidade de sílica na secção transversal da fibra, aumentando a interação acusto-óptica no núcleo. Modulação experimental da refletividade de FBGs gravadas em duas SCFs diferentes indica evidências do aumento dessa interação. Além disso, um método para induzir acusticamente uma mudança de fase dinâmica em uma FBG com gorjeio, empregando um projeto aperfeiçoado de modulador é mostrado. Posteriormente, uma combinação deste modulador e uma FBG gravada em uma SCF com três furos de ar é aplicada para modular um laser mode-locked em fibra dopada com itérbio. Para melhorar o projeto do modulador para futuras aplicações, outros dois dispositivos distintos são investigados visando aumentar a interação acusto-óptica, a largura de banda e a frequência (f > 10 MHz). Uma modulação forte de refletividade foi obtida para um modulador baseado em uma fibra com diâmetro reduzido. Além disso, um aumento da largura de banda de modulação (320 pm) foi obtido com um modulador baseado na interação de uma rede de período longo radial (RLPG) e uma FBG gravada em uma fibra convencional. Em resumo, os resultados mostram uma redução considerável do comprimento da rede/fibra e do tamanho do modulador, indicando possibilidades de dispositivos acusto-ópticos mais rápidos e compactos em fibra. Além disso, o aumento da eficiência de interação, da largura de banda modulada e da frequência, pode ser útil para reduzir a largura do pulso de lasers mode-locked totalmente em fibra, assim como, para outros dispositivos que requerem o controle da luz em fibras ópticas usando ondas acústicas sintonizáveis eletricamente.
This thesis aims to investigate the interaction of acoustic waves and fiber Bragg gratings (FBGs) in standard and suspended-core fibers (SCFs), to evaluate the influence of the fiber, grating and modulator design on the increase of the modulation efficiency, bandwidth and frequency. Initially, the frequency response and the resonant acoustic modes of a low frequency acousto-optic modulator (f < 1.2 MHz) are numerically investigated by using the finite element method. Later, the interaction of longitudinal acoustic waves and FBGs in SCFs is also numerically investigated. The fiber geometric parameters are varied and the strain and grating properties are simulated by means of the finite element method and the transfer matrix method. The study indicates that the air holes composing the SCF cause a significant reduction of the amount of silica in the fiber cross section increasing acousto-optic interaction in the core. Experimental modulation of the reflectivity of FBGs inscribed in two distinct SCFs indicates evidences of this increased interaction. Besides, a method to acoustically induce a dynamic phase-shift in a chirped FBG employing an optimized design of modulator is shown. Afterwards, a combination of this modulator and a FBG inscribed in a three air holes SCF is applied to mode-lock an ytterbium doped fiber laser. To improve the modulator design for future applications, two other distinct devices are investigated to increase the acousto-optic interaction, bandwidth and frequency (f > 10 MHz). A high reflectivity modulation has been achieved for a modulator based on a tapered fiber. Moreover, an increased modulated bandwidth (320 pm) has been obtained for a modulator based on interaction of a radial long period grating (RLPG) and a FBG inscribed in a standard fiber. In summary, the results show a considerable reduction of the grating/fiber length and the modulator size, indicating possibilities for compact and faster acousto-optic fiber devices. Additionally, the increased interaction efficiency, modulated bandwidth and frequency can be useful to shorten the pulse width of future all-fiber mode-locked fiber lasers, as well, to other photonic devices which require the control of the light in optical fibers by electrically tunable acoustic waves.
Hofmann, Matthias. "TEM-Untersuchungen zum Gefüge und zu mechanischen Spannungen in Metallisierungen für SAW-Bauelemente." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1189001442992-14894.
Повний текст джерелаHofmann, Matthias. "TEM-Untersuchungen zum Gefüge und zu mechanischen Spannungen in Metallisierungen für SAW-Bauelemente." Doctoral thesis, Technische Universität Dresden, 2006. https://tud.qucosa.de/id/qucosa%3A25031.
Повний текст джерелаBaghalian, Amin. "Detecting Structural Defects Using Novel Smart Sensory and Sensor-less Approaches." FIU Digital Commons, 2017. https://digitalcommons.fiu.edu/etd/3560.
Повний текст джерелаTofel, Pavel. "Nelineární elektro-ultrazvuková spektroskopie rezistorů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-233559.
Повний текст джерелаPerodou, Arthur. "Frequency design of passive electronic filters : a modern system approach." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEC046.
Повний текст джерелаThe current explosion of communicating devices (smartphones, drones, IoT...), along with the ever-growing data to be transmitted, produces an exponential growth of the radiofrequency bands. All solutions devised to handle this increasing demand, such as carrier aggregation, require to synthesise frequency filters with stringent industrial requirements (performance, energy consumption, cost ...). While the technology of acoustic wave (AW) resonators, that seem to be the only passive micro-electronic components available to fulfil these requirements, is mature, the associate design problem becomes dramatically complex. Traditional design methods, based on the intuition of designers and the use of generic optimisation algorithms, appear very limited to face this complexity. Thus, systematic and efficient design methods need to be developed. The design problem of AW filters happens to be an instance of the more general design problem of passive electronic filters, that played an important role in the early development of Linear Control and System theory. Systematic design methods were developed in particular cases, such as for LC-ladder filters, but do not enable to tackle the case of AW filters. Our aim is then to revisit and generalise these methods using a modern System approach, in order to develop systematic and efficient design methods of passive electronic filters, with a special focus on AW filters. To achieve this, the paradigm of convex optimisation, and especially the sub-class of Linear Matrix Inequality (LMI) optimisation, appears for us a natural candidate. It is a powerful framework, endowed with efficient solvers, able to optimally solve a large variety of engineering problems in a low computational time. In order to link the design problem with this framework, it is proposed to use modern tools such as the Linear Fractional Transformation (LFT) representation and a mathematical characterisation coming from Dissipative System theory. Reviewing the different design methods, two design approaches stand out. The first approach consists in directly tuning the characteristic values of the components until the frequency requirements are satisfied. While very flexible and close to the original problem, this typically leads to a complex optimisation problem with important convergence issues. Our first main contribution is to make explicit the sources of this complexity and to significantly reduce it, by introducing an original representation resulting from the combination of the LFT and the Port-Hamiltonian Systems (PHS) formalism. A sequential algorithm based on LMI relaxations is then proposed, having a decent convergence rate when a suitable initial point is available. The second approach consists of two steps. First, a transfer function is synthesised such that it satisfies the frequency requirements. This step is a classical problem in Control and Signal Processing and can be efficiently solved using LMI optimisation. Second, this transfer function is realised as a passive circuit in a given topology. To this end, the transfer function needs to satisfy some conditions, namely realisation conditions. The issue is to get them with a convex formulation, in order to keep efficient algorithms. As this is generally not possible, an idea is to relax the problem by including common practices of designers. This leads to solve some instances of a general problem denoted as frequency LFT filter synthesis. Our second main contribution is to provide efficient synthesis methods, based on LMI optimisation, for solving these instances. This is achieved by especially generalising the spectral factorisation technique with extended versions of the so-called KYP Lemma. For particular electronic passive filters, such as bandpass LC-ladder filters, this second approach allows to efficiently solve the design problem. More generally, it provides an initial point to the first approach, as illustrated on the design of a particular AW filter
Mace, Richard Lester. "Linear and nonlinear electron-acoustic waves in plasmas with two electron components." Thesis, 1991. http://hdl.handle.net/10413/8353.
Повний текст джерелаThesis (Ph.D.)-University of Natal, Durban, 1991.
Tracy, Lisa A. "Studies of Two Dimensional Electron Systems via Surface Acoustic Waves and Nuclear Magnetic Resonance Techniques." Thesis, 2008. https://thesis.library.caltech.edu/4397/1/All_Thesis_external.pdf.
Повний текст джерелаThis thesis presents measurements investigating the spin degree of freedom in two dimensional electron systems (2DES’s). The measurements use nuclear magnetic resonance (NMR) techniques to study the role of spin in several 2DES states.
We first examine the spin transition that occurs in a half-filled Landau level in a single layer 2DES and compare our measurements to expectations from a composite fermion (CF) model. We show the temperature and density dependence of the nuclear T1 and resistively-detected NMR signal. The T₁ data can be roughly understood via a Korringa-like model of nuclear spin relaxation. However, the observed density dependence of both T₁ and the NMR signal is not explained by conventional CF theory.
We next consider a bilayer 2DES consisting of two closely spaced 2D electron layers, where each of the individual layers contains a half-filled Landau level. In this system, a transition occurs from a compressible single layer-like state to an incompressible correlated bilayer state as a function of the effective spacing between the two layers. When the effective spacing is made small enough, interactions between the two layers lead to the formation of a new state that can be viewed as a Bose condensate of excitons. Using NMR techniques we show that the spin degree of freedom is active during this transition.
In a single-layer 2DES with one completely filled Landau level (ν = 1), charged spin-texture excitations called skyrmions" are expected to exist. We probe the spin dynamics near this state using NMR. We find relatively fast nuclear relaxation rates that are consistent with a theory of spin excitations for a skyrmion solid. Our measurements also provide clues as to the origin of an "anomalous" NMR lineshape seen near ν=1.
We also present surface acoustic wave (SAW) measurements in a low density 2DES at zero magnetic field, under conditions where a 2D metal-insulator transition may occur. We find that our SAW data are consistent with a disorder-driven, percolation-type transition.
Hsu, Chao-Hung, and 徐兆宏. "Pseudo-LFE Acoustic Wave Sensors with Different Electrode Configurations." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/91001495359124349369.
Повний текст джерела大同大學
機械工程學系(所)
100
Pseudo lateral field excited (Pseudo-LFE) acoustic wave sensors exhibit stable oscillation in the air due to low electric impedance. Although they are capable of detecting liquid electrical property changes, the sensitivity is not as large as lateral field excited (LFE) acoustic wave sensors. Therefore, this study modifies the sensing electrode geometry to increase sensitivity of a Pseudo-LFE sensor. At first the finite element software, COMSOL, was used to analyze the resonance modes and sensitivities of Pseudo-LFE sensors with various sensing electrode geometries to liquid viscosity, permittivity, and conductivity. Moreover, Pseudo-LFE sensors with ring-shape sensing electrodes were fabricated on AT-cut quartz and measured with an oscillator circuit or network analyzer when contacting with glycerol, 2-propanol, or NaCl solution. The simulation results exhibit similar trend and comparable values with the experiments, verifying the validity of the simulation model proposed here. Besides, Pseudo-LFE sensors with ring-shape sensing electrodes show a comparable sensitivity with LFE sensors and can measure glycerol and 2-propanol solutions of high concentration or less volume. In conclusion, Pseudo-LFE sensors with ring-shape sensing electrodes are potential in sensor applications instead of QCM (quartz crystal microbalance) and LFE sensors because of large sensitivity and wide sensing range.
Wu, Jun-xian, and 吳俊賢. "A Study on Metallic Electrode Materials of Surface Acoustic Wave Devices." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/99537812176450420581.
Повний текст джерела義守大學
材料科學與工程學系碩士班
93
The surface characteristic, mechanical properties and microstructure of the sputtered Al and Ti film on quartz and LiTaO3 piezoelectric structure were investigated in this study. The influences of the simulated reflow process and HTS reliability test were studied by using Alpha-step, Nanoindenter and Adhesive force tester on the deposited film. The experimental content of this study includes the relationship between film thickness and film roughness, temperature effect on the film properties, and the influences of temperature on the adhesion between film and structure. Experimental results show that the roughness of the deposited metallic film increases with increasing sputtering time. Surface properties of the film were varied after simulated reflow process and HTS aging process. It was also found that the influences of the HTS aging time on the mechanical properties and the adhesion of the metallic film depend on factors such as types of piezoelectric substrate and types of the deposited metallic film.
鄭憲明. "Using High-Frequency Surface-Acoustic-Wave to Probe Magnetotransport property of Semiconductor Two-Dimensional Electron System." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/13045184024452405297.
Повний текст джерела國立中興大學
物理學系
90
We report the conductivity variations of two-dimensional electron systems (2DESs) confined in semiconductor heterostructures in low-temperature (~0.4K) and high-magnetic-field environments by using high-frequency surface acoustic waves (SAWs) generated by an inter digital transducer (IDT) on a piezoelectric substrate (GaAs or LiNO3). The variations of SAW velocity and attenuation due to the conductivity change near the surface are detected by a phase-lock loop and a power detector respectively. We use pulse-modulated microwave signal and gated-averaging technique to reduce the heating and noise.
Li, Cheng-Han, and 李承漢. "Interface Circuits for a Portable Electronic Nose Based on Surface Acoustic Wave Sensor Array." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/57137278871938393873.
Повний текст джерела國立清華大學
電機工程學系
98
Electronic nose system is the world's popular field of studies, it can be widely applied to various industries and daily life. This thesis hopes to increase the convenience of the electronic nose system, the applicable site of electronic nose system can’t be constraints, and low cost. Surface Acoustic Wave sensors with high sensitivity, fast response, etc., is very suitable for as gas sensors. Use of non-continuous surface acoustic wave gas sensor array measured power consumed by the lower, extend the operating hours of portable devices. It realization of SAW sensor interface circuits by using 0.18μm CMOS process in this work. The three types of circuits are digital, analog and mixed-mode SAW array interface circuit, the performance of the mixed-mode circuits is the best one, the power consumption is only 1.48mW, the resolution is 10Hz, suitable for the SAW output frequency of about 100MHz sensor array. The interface can be combined with wireless transmission to send data to the receiver storage and analysis.
Li, Changying. "Sensor fusion models to integrate electronic nose and surface acoustic wave sensor for apple quality evaluation." 2006. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-1567/index.html.
Повний текст джерелаBaalman, Marije Alberdina Johanna [Verfasser]. "On wave field synthesis and electro acoustic music, with a particular focus on the reproduction of arbitrarily shaped sound sources / vorgelegt von Marije Alberdina Johanna Baalman." 2008. http://d-nb.info/989646890/34.
Повний текст джерела(10285355), Matthew J. Storey. "Lithium Niobate Acoustoelectric Platforms for Integrated Non-Reciprocal RF MEMS Devices." Thesis, 2021.
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