Teses / dissertações sobre o tema "Radiofrequency"
Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos
Veja os 50 melhores trabalhos (teses / dissertações) para estudos sobre o assunto "Radiofrequency".
Ao lado de cada fonte na lista de referências, há um botão "Adicionar à bibliografia". Clique e geraremos automaticamente a citação bibliográfica do trabalho escolhido no estilo de citação de que você precisa: APA, MLA, Harvard, Chicago, Vancouver, etc.
Você também pode baixar o texto completo da publicação científica em formato .pdf e ler o resumo do trabalho online se estiver presente nos metadados.
Veja as teses / dissertações das mais diversas áreas científicas e compile uma bibliografia correta.
Gananadha, Sivakumar St George UNSW. "Radiofrequency ablation in oncology". Awarded by:University of New South Wales. St George, 2006. http://handle.unsw.edu.au/1959.4/24347.
Texto completo da fonteHuang, Wei. "Radiofrequency antennas designs for medical applications /". Full text available from ProQuest UM Digital Dissertations, 2009. http://0-proquest.umi.com.umiss.lib.olemiss.edu/pqdweb?index=0&did=1917255731&SrchMode=1&sid=1&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1278527663&clientId=22256.
Texto completo da fonteWilén, Jonna. "Radiofrequency fields – exposure, dose and health". Doctoral thesis, Umeå University, Radiation Sciences, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-4.
Texto completo da fonteThe overall aim of this thesis is to increase our knowledge of relevant exposure parameters when discussing possible health implication from exposure to radiofrequency electromagnetic fields (RF), especially effects that might occur at non-thermal levels.
In this thesis an effort is made to broaden the exposure assessment and to take the exposure time into account and combine it with the Specific Absorption Rate (SAR) and the field parameters (electric and magnetic field strength) to approach a dose concept.
In the first part of the thesis self-reported subjective symptoms among mobile phone users were studied. As a basis for this an epidemiological study among mobile phone users was completed with the main hypothesis that users of the digital transmission system GSM experience more symptoms than users of the older analogue NMT transmission system.
The hypothesis was falsified, but an interesting side finding was that people with longer calling time per day experienced more symptoms than people with shorter calling time per day. The time-aspect (long duration phone call etc.) was also found to be relevant for the occurrence of symptoms in association with mobile phone use as well as duration of symptoms. The new suggested dosimetric quantity Specific Absorption per Day (SAD), in which both calling time per day as well as the measured SAR1g are included showed a stronger association to the prevalence of some of the symptoms, such as dizziness, discomfort and warmth behind the ear compared to both CT and SAR1g alone.
In the second part whole body exposure conditions were considered. Methods to measure the induced current were examined in an experimental study, where different techniques were compared in different grounding conditions. The results were used in a study of operators of RF plastic sealers (RF operators) where the health status as well as the exposure were studied. The results showed that RF operators are a highly exposed group, which was confirmed by the fact that 16 out of 46 measured work places exceeded the ICNIRP guidelines. Headaches were found to be associated with the mean value of the time integrated E-field during a weld (E-weld) and the warmth sensations in the hands (warm hands) with the time integrated E-field exposure during one day (E-day).
The general findings in this thesis indicated that time should be included in the exposure assessment when studying non-thermal effects such as subjective symptoms in connection with RF exposure. The thesis proposes two different methods for doing this, namely timeintegrated exposure [V/m x t and A/m x t] and dose [J/kg].
Floume, Timmy. "Optical monitoring of radiofrequency tissue fusion". Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526407.
Texto completo da fonteDawber, W. N. "Radiofrequency analysis using optical signal processing". Thesis, University of St Andrews, 1991. http://hdl.handle.net/10023/15035.
Texto completo da fonteWalter, Aaron Joseph. "Approximate Thermal Modeling of Radiofrequency Cardiac Ablation". Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd1002.pdf.
Texto completo da fonteLunney, Matthew David Norwood. "Dynamics of ions in radiofrequency quadrupole traps". Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65463.
Texto completo da fonteGray, Andrew James. "Higher resolution laser-radiofrequency double resonance spectroscopy". Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259598.
Texto completo da fonteMorris, I. D. "Radiofrequency studies at low and intermediate temperatures". Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236305.
Texto completo da fonteSkubis, Mark D. (Mark David) 1974. "Radiofrequency losses in an NMR surface coil". Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/47687.
Texto completo da fonteIncludes bibliographical references (leaves 58-65).
Radiofrequency energy loss has been investigated for a resonant NMR surface coil between 20 MHz and 400 MHz. High-field NMR (> 64 MHz) is used increasingly for human imaging and spectroscopy to achieve improved SNR and spectral resolution. RF losses in coils designed using conventional lumped-element principles, however, often limit the practicality of high-field imaging. New design principles are required for the construction of efficient high-field RF coils. The RF energy losses investigated include RF coil losses and losses to a phantom load. These were studied using single-loop, resonant surface coils. Coil Q values, both unloaded and loaded, were measured and used to determine the coil radiation resistance, load resistance, B, field magnitude, and SNR. Radiation resistance is shown to increase like RR ~ f04. It is widely believed that load losses dominate all other losses in biomedical NMR. This study indicates that limiting radiation losses may improve loaded coil SNR at high frequencies. To this end, one may decrease the coil electrical length and/or apply transmission line principles in the construction of RF coils. Decreasing the coil electrical wavelength may be accomplished by decreasing the coil dimensions. Transmission line principles, which have been demonstrated for volume coils, improve performance by minimizing the coil radiation resistance.
by Mark D. Skubis.
S.M.
Piqueras, Ruipérez Miguel Ángel. "Photonic Vector Processing Techniques for Radiofrequency Signals". Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/63264.
Texto completo da fonte[ES] El procesamiento de señales de radiofrecuencia (RF) utilizando medios fotónicos es una disciplina que apareció casi al mismo tiempo que el láser y la fibra óptica. La fotónica ofrece la capacidad de manipular señales de radiofrecuencia de banda ancha, una baja atenuación, procesados basados en una amplia variedad de fenómenos lineales y no lineales y, recientemente, el potencial para implementar subsistemas fotónicos integrados. Estas características ofrecen un gran potencial para la implementación de múltiples funcionalidades incluyendo transporte óptico, conversión de frecuencia, filtrado óptico de RF, multiplexación y demultiplexación de señales, encaminamiento y conmutación, muestreo óptico, generación de tonos, líneas de retardo, conformación de haz en agrupaciones de antenas o generación fotónica de modulaciones digitales, e incluso una combinación de varias de estas funcionalidades. Esta tesis se centra en la aplicación del procesamiento vectorial en el dominio óptico de señales de radiofrecuencia en dos campos de aplicación: la conformación óptica de haces y la modulación y demodulación vectorial fotónica de señales digitales en cuadratura. El control fotónico vectorial permite manipular la amplitud y fase de las señales de radiofrecuencia en el dominio óptico, que es el procesamiento fundamental que se requiere en diferentes aplicaciones tales como las redes de conformación de haces para agrupaciones de antenas y en la modulación en cuadratura. El trabajo descrito en esta tesis incluye diferentes técnicas para implementar una versión fotónica de las redes de conformación de haces de en agrupaciones de antenas, conocidas como redes ópticas de conformación de haces (OBFN). Se estudian dos familias de redes: arquitecturas de retardo en fibra óptica y arquitecturas integradas. Las primeras permiten el control de señales de banda ancha utilizando fibras ópticas dispersivas con técnicas de multiplexado por división de longitud de onda y funcionalidades avanzadas tales como la estimación del ángulo de llegada de la señal en la antena receptora. En la segunda, se estudian redes de conformación pasivas basadas en Matrices de Butler ópticas integradas, incluyendo una solución ultra-compacta utilizando técnicas ópticas heterodinas en silicio sobre aislante (SOI), y una alternativa homodina en sílice dopado con germanio. En esta tesis, también se han investigado técnicas de procesado vectorial fotónico para la generación de modulaciones digitales en cuadratura. Las modulaciones multinivel codifican la información digital en estados discretos de fase y amplitud de una señal eléctrica para aumentar su eficiencia espectral, como por ejemplo la modulación en cuadratura. El procesado necesario para generar y demodular este tipo de señales implica el procesamiento vectorial (control de amplitud y fase) y la conversión de frecuencia. A diferencia de la implementación electrónica o digital convencional, en esta tesis se estudian diferentes técnicas de procesado fotónico tanto para la generación de modulaciones digitales (modulación vectorial fotónica, PVM) como para su demodulación (PVdM). Esto es de particular interés en el caso de señales de banda ancha, donde la velocidad de datos requerida es del orden de gigabits por segundo, para aplicaciones como backhaul inalámbrico de redes ópticas metropolitanas (conocida como fibra hasta el aire). Las técnicas descritas se basan en explotar la dispersión cromática de la fibra óptica, la multiplexación por división de longitud de onda y la conversión en frecuencia. Además, se presenta una solución heterodina implementada monolíticamente en un circuito integrado fotónico (PIC).
[CAT] El processament de senyals de radiofreqüència (RF) utilitzant mitjans fotònics és una disciplina que va aparèixer gairebé al mateix temps que el làser i la fibra òptica. La fotònica ofereix la capacitat de manipular senyals de radiofreqüència de banda ampla, una baixa atenuació, processats basats en una àmplia varietat de fenòmens lineals i no lineals i, recentment, el potencial per implementar subsistemes fotònics integrats. Aquestes característiques ofereixen un gran potencial per a la implementació de múltiples funcionalitats incloent transport òptic, conversió de freqüència, filtrat òptic de RF, multiplexació i demultiplexació de senyals, encaminament i commutació, mostreig òptic, generació de tons, línies de retard, conformació de feix en agrupacions d'antenes i la generació fotònica de modulacions digitals, i fins i tot una combinació de diverses d'aquestes funcionalitats. Aquesta tesi es centra en l'aplicació del processament vectorial en el domini òptic de senyals de radiofreqüència en dos camps d'aplicació: la conformació òptica de feixos i la modulació i demodulació vectorial fotònica de senyals digitals en quadratura. El control fotònic vectorial permet manipular l'amplitud i la fase dels senyals de radiofreqüència en el domini òptic, que és el processament fonamental que es requereix en diferents aplicacions com ara les xarxes de conformació de feixos per agrupacions d'antenes i en modulació multinivell. El treball descrit en aquesta tesi inclou diferents tècniques per implementar una versió fotònica de les xarxes de conformació de feixos en agrupacions d'antenes, conegudes com a xarxes òptiques de conformació de feixos (OBFN), amb els objectius de proporcionar un control precís en aplicacions terrestres de senyals de banda ampla a freqüències molt altes per sobre de 40 GHz en antenes de comunicacions, optimitzant la mida i el pes quan es compara amb els homòlegs elèctrics en aplicacions espacials, i la presentació de noves funcionalitats fotòniques per agrupacions d'antenes. Per tant, s'estudien dues famílies de OBFNs: arquitectures de retard en fibra òptica i arquitectures integrades. Les primeres permeten el control de senyals de banda ampla utilitzant fibres òptiques dispersives amb tècniques de multiplexació per divisió en longitud d'ona i funcionalitats avançades com ara l'estimació de l'angle d'arribada del senyal a l'antena receptora. A la segona, s'estudien xarxes de conformació passives basades en Matrius de Butler òptiques en fotònica integrada, incloent una solució ultra-compacta utilitzant tècniques òptiques heterodinas en silici sobre aïllant (SOI), i una alternativa homodina en sílice dopat amb germani. D'altra banda, també s'ha investigat en aquesta tesi tècniques de processament vectorial fotònic per a la generació de modulacions digitals en quadratura. Les modulacions multinivell codifiquen la informació digital en estats discrets de fase i amplitud d'un senyal elèctric per augmentar la seva eficiència espectral, com ara la modulació en quadratura. El processat necessari per generar i desmodular aquest tipus de senyals implica el processament vectorial (control d'amplitud i fase) i la conversió de freqüència. A diferència de la implementació electrònica o digital convencional, en aquesta tesi s'estudien diferents tècniques de processament fotònic tant per a la generació de modulacions digitals (modulació vectorial fotònica, PVM) com per la seva demodulació (PVdM). Això és de particular interès en el cas de senyals de banda ampla, on la velocitat de dades requerida és de l'ordre de gigabits per segon, per a aplicacions com backhaul sense fils de xarxes òptiques metropolitanes (coneguda com fibra fins l'aire). Les tècniques descrites es basen en explotar la dispersió cromàtica de la fibra òptica, la multiplexació per divisió en longitud d'ona i la conversió en freqüència. A més, es prese
Piqueras Ruipérez, MÁ. (2016). Photonic Vector Processing Techniques for Radiofrequency Signals [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/63264
TESIS
Read, Smith Sarah Jane. "The effects of radiofrequency electromagnetic fields on cognition". Thesis, University of Surrey, 2007. http://epubs.surrey.ac.uk/843071/.
Texto completo da fonteKhargi, Krishna. "Surgical treatment of atrial fibrillation using radiofrequency ablation". [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2005. http://dare.uva.nl/document/79584.
Texto completo da fonteNg, Kwok-chai Kelvin. "Clinical applications of radiofrequency ablation for hepatocellular carcinoma". Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39557674.
Texto completo da fonteFarhat, Sedig. "Radiofrequency coils for ultra-high field body MRI". Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/28847/.
Texto completo da fonteNg, Kwok-chai Kelvin, e 吳國際. "Clinical applications of radiofrequency ablation for hepatocellular carcinoma". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39557674.
Texto completo da fonteHoulding, T. K. "Application of radiofrequency heating in catalytic reaction engineering". Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.676521.
Texto completo da fonteRadha, Kumaran Binoy. "Physiological and clinical effects of radiofrequency-based therapy". Thesis, University of Hertfordshire, 2017. http://hdl.handle.net/2299/19813.
Texto completo da fonteHasimoto, Fabio Nishida. "Radiofrequência no tratamento da hiperidrose primária. Revisão sistemática". Botucatu, 2017. http://hdl.handle.net/11449/150069.
Texto completo da fonteResumo: Introdução: A hiperidrose primária (HP) é um distúrbio caracterizado pela sudorese excessiva, levando a uma piora na qualidade de vida de seus portadores. Objetivo: Determinar a efetividade da radiofrequência (RF) no tratamento da HP. Método: Revisão sistemática de ensaios clínicos randomizados, estudos controlados e estudos observacionais em indivíduos portadores de HP, nos quais foram realizados o tratamento por RF comparado com qualquer outra modalidade de tratamento ou em que foram comparados os resultados antes e após a intervenção no tratamento isolado por RF. Os desfechos avaliados foram: grau de intensidade da hiperidrose, qualidade de vida, sudorese compensatória e recorrência dos sintomas. Resultados: Foram selecionados dez estudos, oito deles (204 participantes) empregando somente a RF (74 microagulhamentos e 130 ablações) e dois (65 participantes) comparando a RF com a simpatectomia videotoracoscópica. Houve redução da intensidade da HP no subgrupo que aplicou microagulhamento (3 estudos, 74 participantes, diferença média -1,24, IC 95% -1,44 a -1,03, I2=50%). Em um estudo em que se realizou ablação simpática por RF (36 participantes) houve maior redução da intensidade da HP do que nos três estudos em que se realizou microagulhamento (-2,56, IC 95% -2,76 a -2,36 versus -1,24, IC 95% -1,44 a -1,03). Houve melhora na qualidade de vida após ablação simpática (2 estudos, diferença média -15,92, IC 95% -17,61 a -14,24, I²= 23%). No microagulhamento também houve melhora ... (Resumo completo, clicar acesso eletrônico abaixo)
Doutor
Toupin, Solenn. "Cardiac MR thermometry for the monitoring of radiofrequency ablation". Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0346/document.
Texto completo da fonteRadiofrequency ablation is a therapeutic procedure for the treatment of cardiac arrhythmia by inducing a local necrosis of the arrhythmogenic tissue. This intervention is currently performed without online imaging of the lesion formation during radiofrequency delivery. MR thermometry provides a monitoring of temperature in the targeted tissue in each pixel and an immediate estimation of lesion via the calculation of the thermal dose. If this technique is well established for the guidance of tumor ablation in various organs, it remains challenging in the heart due to motion (breathing and myocardial contraction). In this work, a cardiac MR thermometry method was developed to perform a real-time temperature mapping of the heart under free-breathing conditions. Several MR pulse sequences were designed to ensure the acquisition of up to 5 slices per heartbeat with a voxel size of 1.6X1.6X3 mm3. Different solutions of minimization of out-of-plane motion were evaluated: alignment of the slices in the main direction of displacement, dynamic update of slice position depending on the respiratory state (echo-navigator, measure of the catheter position). Residual in-plane motion and associated susceptibility artifacts were corrected by real-time algorithms to allow a precision of MR thermometry of ±2°C in ventricles. This protocol was successfully used for the monitoring of radiofrequency ablation in sheep (N=3), allowing a correlation (R=87) between thermal dose maps and sizes of created lesions. These results are promising regarding the relevance of this measure for an inline estimation of the lesion extent during ablation
Phipps, Jeffrey Howard. "Radiofrequency induced thermal endometrial ablation : invention and primary assessment". Thesis, University of Leicester, 1991. http://hdl.handle.net/2381/33169.
Texto completo da fonteEriksson, Ola. "Characterisation and modelling of radiofrequency lesioning in functional neurosurgery /". Linköping : Univ, 2001. http://www.bibl.liu.se/liupubl/disp/disp2001/tek693s.pdf.
Texto completo da fonteWedge, Christopher J. "Radiofrequency Magnetic Field Effects on Radical Pair Recombination Reactions". Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.515011.
Texto completo da fonteLattanzi, Riccardo. "Radiofrequency detector coil performance maps for parallel MRI applications". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36187.
Texto completo da fonteIncludes bibliographical references (p. 67-70).
Parallel MRI techniques allow acceleration of MR imaging beyond traditional speed limits. In parallel MRI, arrays of radiofrequency (RF) detector coil arrays are used to perform some degree of spatial encoding which complements traditional encoding using magnetic field gradients. As the acceleration factor increases, coil design becomes critical to the overall image quality. The quality of a design is commonly judged on how it compares with other coil configurations. A procedure to evaluate the absolute performance of RF coil arrays is proposed. Electromagnetic calculations to compute the ultimate intrinsic signal-to-noise ratio (SNR) available for any physically realizable coil array are shown, and coil performance maps are generated based on the ratio of experimentally measured SNR to this ultimate intrinsic SNR.
by Riccardo Lattanzi.
S.M.
O'Neill, David Patrick. "Mathematical modelling of the effects of hepatic radiofrequency ablation". Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:b9ff47fd-0e1a-4ca6-a937-a7e4d49841ba.
Texto completo da fonteTuggle, James Robert Jr. "Advanced Characterization of Materials for Superconducting Radiofrequency Accelerator Cavities". Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/90574.
Texto completo da fonteDoctor of Philosophy
Particle accelerators are a powerful tool that helps us expand our knowledge of science and how the universe works. Pushing that knowledge further requires us to use more and more powerful particle accelerators. Particle accelerators are based on a very expensive technology: superconducting radio-frequency (SRF) cavities. These cavities are hollow tubes made from niobium and shaped in such a way as to cause electromagnetic waves to form. These waves are what are used to accelerate particles. The energy input and loss of energy as heat are massive resulting in millions of dollars a year in electric bills at particle accelerator facilities. In order to build bigger and more powerful particle accelerates they most be more efficient or they become prohibitively expensive. In this dissertation I look at several next generation materials used in building particle accelerators. In particular I describe and go into detail about how to characterize these materials. In other words, how we determine the materials properties and how those properties affect the performance.
González, Suárez Ana. "Computational Models and Experimentation for Radiofrequency-based Ablative Techniques". Doctoral thesis, Universitat Politècnica de València, 2014. http://hdl.handle.net/10251/36502.
Texto completo da fonteGonzález Suárez, A. (2014). Computational Models and Experimentation for Radiofrequency-based Ablative Techniques [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/36502
TESIS
Leyssenne, Laurent. "Design of reconfigurable radiofrequency power amplifiers for wireless applications". Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13901.
Texto completo da fonteAbstract
Knipe, Phillip. "Measurement and simulation of radiofrequency emissions from telecommunications transmitters". Thesis, Knipe, Phillip (2013) Measurement and simulation of radiofrequency emissions from telecommunications transmitters. PhD thesis, Murdoch University, 2013. https://researchrepository.murdoch.edu.au/id/eprint/23793/.
Texto completo da fonteLahti, Carl Andrew. "The design of the radio frequency (RF) subsystem printed circuit boards for the Petite Amateur Navy Satellite (PANSAT)". Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA333403.
Texto completo da fonteThesis advisors, Randy L. Borchardt, Rudlof Panholzer. Includes bibliographical references (p. 99). Also available online.
Freeman, Alan John. "Measurement of physiological parameters with echo-planar imaging". Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262655.
Texto completo da fonteMiri, Simin. "Design of catalyst composites for hydrocracking in a R.F. powered reactor". Thesis, Teesside University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285732.
Texto completo da fonteHabermacher, Kathrin. "Device-less patent foramen ovale closure by radiofrequency thermal energy /". [S.l.] : [s.n.], 2009. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
Texto completo da fonteAdams, Jacob James. "A coupled electromagnetic-thermal model of heating during radiofrequency ablation". Connect to resource, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1191454972.
Texto completo da fonteGoruppa, Alexander. "Modifications of radiofrequency capacitive discharge for deposition of carbon coatings". Thesis, Open University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251396.
Texto completo da fonteDanilich, Michael Joseph. "Functional group control in radiofrequency plasma polymers with biomedical applications". Case Western Reserve University School of Graduate Studies / OhioLINK, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1061404856.
Texto completo da fontePadormo, Francesco. "Advanced methods for mapping the radiofrequency magnetic fields in MRI". Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/14630.
Texto completo da fonteBhavaraju, Naresh Chandra. "Heat transfer modeling during radiofrequency cardiac ablation in swine myocardium /". Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
Texto completo da fonteHaggard, Asher. "Identification of Intercostal Vessels Using Spectral Analysis of Ultrasound Radiofrequency Signals". Thesis, Southern Illinois University at Edwardsville, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10686414.
Texto completo da fonteIn a pilot study, radiofrequency backscatter data was collected in the paravertebral (PV) spaces of 4 healthy individuals. Using the associated gray scale ultrasound and Doppler data as guidance, regions-of-interest (ROIs) were chosen inside vessel in the PV space and outside vessel.. ROI sizes of 1.0 mm, 1.5 mm, and 2.0 mm square were examined for auto-regressive (AR) orders of 10, 20, 30, and 40 and bandwidths of 3dB, 6dB, 20dB. Spectral estimations were performed for each ROI size, AR order, and bandwidth over the A-lines of the ultrasound radiofrequency (RF) data. The spectra were averaged and normalized using data collected from a tissue phantom (Siemens S3000 with a 9L4 probe, Siemens Medical Solutions USA, Inc., Malvern, PA). Eight spectral parameters—Y-intercept, slope, and mid-band fit of the regression line, maximum dB of the spectra, frequency at maximum dB, minimum dB of the spectra, frequency at minimum dB, and integrated backscatter were calculated for each spectral estimate and used create ensembles of bagged tree classifiers. An AR order of 10, bandwidth of 6 dB, and an ROI size of 1.0 mm resulted in the minimum out-of-bag error. An additional random forest, using these chosen values, was created from 70% of the data and evaluated independently with the remaining 30% of data. The random forest achieved a predictive accuracy of 92% and Youden’s Index of 0.85. These results suggest that spectral analysis of ultrasound RF backscatter has the potential to identify intercostal blood vessels.
Using the associated gray scale ultrasound and Doppler data as guidance, regions-of-interest (ROIs) were chosen to represent five tissue types found in and around the PV space—rib, pleura, superior costotransverse ligament, intercostal vessel (artery or vein), and the PV space away from the vessel. An ROI size of 2.0 mm, bandwidth of 20 dB, and AR order 10 had the lowest out-of-bag OOB error at 0.315, and averaged across all tissue types, an accuracy of 89.15%, sensitivity of 0.70, specificity of 0.93, and Youden’s Index (YI) of 0.62. These results show that the identification of the five tissues types in radiofrequency backscatter from intercostal ultrasound is feasible.
Another ROI type was added, rib, along with 2-D spectral parameters, real and complex cepstral peaks were added to the data set. All 5 frames of ultrasound data were used to grow the database by a factor of 5. Ensembles of bagged trees created using ROIs of size 2.0 mm, bandwidths of 20 dB, and AR order of 10 were found to have the lowest OOB error at 0.123. After retraining the classifier for data with an ROI size of 2.0 mm, bandwidth 20, AR order 10, and 200 trees, for the 30% test data, accuracy was found to be an average of 95.90% across all tissue types, average sensitivity was found to be 0.85 across all tissue types, average specificity was found to be 0.98 across all tissue types, and average YI across all tissue types was found to be 0.83.
Zundert, Jan H. M. Van. "The use of pulsed radiofrequency in the treatment of chronic pain". Maastricht : Maastricht : Universiteit Maastricht ; University Library, Maastricht University [Host], 2005. http://arno.unimaas.nl/show.cgi?fid=6492.
Texto completo da fonteWright, Philippa Anne. "Radiofrequency and optical studies of a quantum two dimensional electron system". Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308672.
Texto completo da fonteBhardwaj, Neil. "Ablation of liver tissue : a comparison between microwave, cryotherapy and radiofrequency". Thesis, University of Leicester, 2011. http://hdl.handle.net/2381/9509.
Texto completo da fonteNg, Kwok-chai Kelvin, e 吳國際. "Local and systemic effects of hepatic radiofrequency ablation in animal models". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B29434920.
Texto completo da fonteAbou-Sherif, Sherif Saad Mohamed. "Morphological effects of radiofrequency (pulsed and continuous) on primary afferent neurons". Thesis, King's College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416619.
Texto completo da fonteSalas, Barenys Arnau. "Full-3D Printed Electronics Fabrication of Radiofrequency Circuits and Passive Components". Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/673257.
Texto completo da fonteAquesta tesi doctoral proposa la idea que la impressió 3D pot canviar el paradigma de l’electrònica de radiofreqüència. S’hi anomenen i expliquen les tecnologies de manufactura additiva existents. Per centrar-se en el principal tema d’interès, s’exposa un compendi d’aplicacions d’electrònica impresa en 3D en el camp de la RF amb el qual s’ha confeccionat l’estat de la qüestió. Un cop exposat el context, el procés de manufactura per a electrònica impresa en 3D que s’ha desenvolupat en el marc d’aquest projecte és descrit i caracteritzat. Aquesta tecnologia consisteix en la impressió en 3D d’un substrat de polímer utilitzant tècniques basades, o bé en estereolitografia, o bé en material jetting. Posteriorment, el component o circuit es metal·litza parcialment mitjançant un procés electrolític ja sigui electroless plating o electroplating. La caracterització inclou les especificacions electromagnètiques del substrat dielèctric i la qualitat de metal·lització, que s’han resultat ser competitives relació amb l’estat de la qüestió. Amb l’objectiu de demostrar les possibilitats de la tecnologia desenvolupada, s’han dissenyat i testejat dispositius electrònics de RF, concebent-los en l’espai tridimensional. El punt clau és que els dispositius dissenyats serien molt difícils, costosos o directament impossibles de fabricar usant tecnologies convencionals. A remarcar, s’ha dut a terme un estudi sobre inductors cònics, mostrant els avantatges d’aquests components per a aplicacions de banda ampla amb dispositius compactes. Aquests inductors shan fet servir per a la fabricació de filtres passius en 3D. A més, a més, s’han dissenyat filtres 3D per ser impresos en una sola part, una tècnica nova que per produir circuits 3D amb components discrets integrats. A part dels circuits d’elements discrets, s’ha dedicat un capítol sencer als dispositius d’elements distribuïts. S’ha dut a terme un estudi sobre línies de transmissió microstrip helicoidals, les quals aporten una millora important de miniaturització dels segments de línia. Partint d’aquí, aquestes línies s’han implementat en el disseny de transformadors d’impedància, que també milloren en termes d’ample de banda, acobladors híbrids de tipus branch-line i acobladors basats en línies acoblades. Aquests dispositius han resultat tenir millores importants de compacitat respecte els dissenys convencionals fabricats en estructures planars.
Easwaran, Kollengode Raghavan. "Spectroscopy and evaporative cooling of rubidium atoms in radiofrequency dressed traps". Paris 13, 2009. http://www.theses.fr/2009PA132007.
Texto completo da fonteIn this thesis, I describe the spectroscopic investigations and preliminary results of evaporative cooling of rubidium atoms done on a magnetic trap dressed with a radiofrequency field. Unlike the case of a static magnetic trap, where a single radiofrequency photon is used to outcouple atoms we have demonstrated that a multiphoton transitions is necessary. This transitions are nearly resonant with the energy spacing of the radiofrequency dressed states. The evaporation efficiency is not the same for all the observed transitions: the transition involving a two photon process is more efficient compared to the others. Preliminary results of evaporative cooling in radiofrequency dressed trap is discussed. The quantum degeneracy is not reached as it is difficult to satisfy the adiabaticity condition in the direction perpendicular to the tightly confined direction in the radiofrequency dressed trap, since the oscillation frequencies are a few Hz in this direction. One way to render the evaporative cooling more efficiently is by increasing the oscillation frequency in this direction. Lastly, we discuss a method to load the atoms into a radiofrequency dressed Quadrupole trap where the oscillation frequency is higher in this direction
Krupka, Tianyi M. "DESIGN OF CONTROLLED AND TARGETED THERMAL SENSITIZER FOR ENHANCING RADIOFREQUENCY ABLATION". Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1275655694.
Texto completo da fonteKoyama, Shin. "Genotoxic effects of extremely low frequency electromagnetic fields and radiofrequency radiation". Kyoto University, 2007. http://hdl.handle.net/2433/136436.
Texto completo da fonte0048
新制・課程博士
博士(人間・環境学)
甲第13165号
人博第372号
新制||人||91(附属図書館)
18||D||173(吉田南総合図書館)
UT51-2007-H438
京都大学大学院人間・環境学研究科相関環境学
(主査)教授 小松 賢志, 助教授 倉橋 和義, 助教授 三浦 智行
学位規則第4条第1項該当
Roper, Ryan Todd. "A Study of Radiofrequency Cardiac Ablation Using Analytical and Numerical Techniques". Diss., CLICK HERE for online access, 2003. http://contentdm.lib.byu.edu/ETD/image/etd262.pdf.
Texto completo da fonteAl, Raisi Sara Ibrahim Abdulkhaliq. "Investigating the Efficacy of Radiofrequency Renal Artery Denervation: From Bench to Bedside". Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/21198.
Texto completo da fonte