Tesis sobre el tema "Short-time Fourier transform"
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Okamura, Shuhei. "The Short Time Fourier Transform and Local Signals". Research Showcase @ CMU, 2011. http://repository.cmu.edu/dissertations/58.
Texto completoHon, Tsz Kin. "Time-frequency analysis and filtering based on the short-time Fourier transform". Thesis, King's College London (University of London), 2013. https://kclpure.kcl.ac.uk/portal/en/theses/timefrequency-analysis-and-filtering-based-on-the-shorttime-fourier-transform(de8bcca8-cd9d-42a3-bf79-281672478744).html.
Texto completoSun, Pu. "Comparison of STFT and Wavelet Transform inTime-frequency Analysis". Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-19072.
Texto completoFredriksson, Henrik. "On the Short-Time Fourier Transform and Gabor Frames generated by B-splines". Thesis, Linnéuniversitetet, Institutionen för datavetenskap, fysik och matematik, DFM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-20262.
Texto completoMacIsaac, Dawn. "Using the short-time Fourier transform to assess localized fatigue in dynamic muscle contractions". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0007/MQ46265.pdf.
Texto completoSchippa, Robert [Verfasser]. "Short-time Fourier transform restriction phenomena and applications to nonlinear dispersive equations / Robert Schippa". Bielefeld : Universitätsbibliothek Bielefeld, 2019. http://d-nb.info/1200097637/34.
Texto completoE, Okwelume Gozie y Ezeude Anayo Kingsley. "BLIND SOURCE SEPARATION USING FREQUENCY DOMAIN INDEPENDENT COMPONENT ANALYSIS". Thesis, Blekinge Tekniska Högskola, Avdelningen för signalbehandling, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-1312.
Texto completoGozie: modebelu2001@yahoo.com Anayo: ezeudea@yahoo.com
Albertini, Alessandro. "Influenza dei parametri della Short-Time Fourier Transform nell’analisi di emissioni condotte nell’intervallo 2-150 kHz". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Buscar texto completoPaneras, Demetrios E. "Efficient STFT analysis over limited frequency regions". Thesis, Boston University, 1992. https://hdl.handle.net/2144/34651.
Texto completoPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
We address the problem of efficiently computing, over narrow frequency bands, the short-time Fourier transform (STFT) and approximations to the STFT. This problem is important for the design of signal understanding systems that have to efficiently carry out STFT reprocessing of signals in order to examine detailed features of signal components that have already been located within narrow frequency bands. In the computation of the exact STFT we use an "overlap pruning" approach (Covell et al. 1992) for exploiting the commonality of computations between successive slices of the STFT with unity decimation interval. We have also extended this approach to the STFT with non-unity decimation intervals and combined it with a frequency pruning method (Sreenivas et al. 1980) to provide additional computational savings. In the computation of approximations to the STFT we use an algorithm (Khan et al. 1988) for efficiently computing Taylor series approximations over narrow frequency bands. Through examples involving real data we demonstrate the feasibility of using the approximated STFT to obtain more accurate estimates of the center frequency of spectral peaks, and to resolve multiple peaks that have been smeared due to the use of short window lengths. The efficiency of all the algorithms we have investigated is less than 0(N log N) multiplications per STFT slice and can be as small as O(N) multiplications per STFT slice in certain cases. Consequently, all the algorithms compare favourably with the standard FFT implementation of the STFT which requires O(N log N) multiplications per slice. All the algorithms considered in this thesis were implemented in software and tested on synthetic and real sound signals.
2031-01-01
Wojcicki, Kamil Krzysztof. "Role of the Short-Time Phase Spectrum in Speech Processing". Thesis, Griffith University, 2011. http://hdl.handle.net/10072/366376.
Texto completoThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
Full Text
Alsteris, Leigh y n/a. "Short-Time Phase Spectrum in Human and Automatic Speech Recognition". Griffith University. School of Microelectronic Engineering, 2006. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20060727.090845.
Texto completoAlsteris, Leigh. "Short-Time Phase Spectrum in Human and Automatic Speech Recognition". Thesis, Griffith University, 2006. http://hdl.handle.net/10072/366602.
Texto completoThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Microelectronic Engineering
Full Text
Rautiainen, J. (Jari). "Novel magnetic resonance imaging techniques for articular cartilage and subchondral bone:studies on MRI Relaxometry and short echo time imaging". Doctoral thesis, Oulun yliopisto, 2015. http://urn.fi/urn:isbn:9789526207643.
Texto completoTiivistelmä Nivelrikko on yleinen nivelsairaus, johon ei tällä hetkellä ole parannuskeinoa. Nivelrikossa nivelrusto rappeutuu asteittain aiheuttaen lopulta kudoksen tuhoutumisen; samanaikaisesti myös rustonalaisessa luussa sekä rusto–luurajapinnassa tapahtuu muutoksia. Nivelrustokudoksen uusiutumiskyky on erittäin heikko, joten vauriot olisi hyvä havaita varhaisessa vaiheessa. Nivelrikon syntymekanismeja ei kuitenkaan vielä täysin ymmärretä, koska nykyiset seurantamenetelmät eivät ole riittävän tarkkoja taudin etenemisen tarkkailemiseksi. Magneettikuvausteknologian kehitys mahdollistaa kuitenkin nivelruston koostumuksen tarkastelun nivelen ulkopuolelta. Kvantitatiivisen magneettikuvauksen avulla (T1, T2, T1ρ, T2ρ, TRAFF, T1sat relaksaatioaikaparametrit) voidaan mitata epäsuorasti nivelruston koostumusta ja rakennetta. SWIFT (Sweep Imaging with Fourier Transform) on uusi lyhyen kaikuajan magneettikuvausmenetelmä, joka mahdollistaa myös erittäin lyhyen T2-relaksaatioajan omaavien kudosten, kuten rusto–luurajapinnan sekä rustonalaisen luun kuvaamisen. Työssä tutkittiin nivelrikossa syntyviä muutoksia nivelrustossa, rusto–luurajapinnassa ja rustonalaisessa luussa erilaisissa eläinmalleissa sekä ihmiskudoksessa. Lisäksi työssä tarkasteltiin eri magneettikuvaustekniikoiden herkkyyttä havaita muutokset näissä kudoksissa. Nivelruston ja rustonalaisen luun ominaisuuksien määrittelemiseen käytettiin verrokkimenetelminä biomekaanisia, histologisia sekä biokemiallisia mittauksia ja tietokonetomografiakuvauksia. Kvantitatiivisista magneettikuvausparametreista adiabaattinen T1ρ sekä adiabaattinen T2ρ osoittautuivat herkimmiksi havaitsemaan muutoksia varhaisen nivelrikon eläinmallissa sekä ihmiskudosnäytteissä. SWIFT-magneettikuvaustekniikka puolestaan mahdollisti sekä rustonalaisen luukudoksen tilan arvioinnin että nivelrikossa tapahtuvien muutosten havainnoinnin rusto–luurajapinnassa. Nämä menetelmät voivat mahdollistaa nivelrikon diagnosoinnin taudin varhaisessa vaiheessa, mutta lisätutkimuksia vaaditaan menetelmien soveltuvuudesta kliiniseen käyttöön
Helienek, Matúš. "Simulační a experimentální analýza řezání kotoučovou pilou". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-412924.
Texto completoGavrilovic, Nenad. "VIBRATION-BASED HEALTH MONITORING OF ROTATING SYSTEMS WITH GYROSCOPIC EFFECT". DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1358.
Texto completoKovačev, Radovan. "Časově-frekvenční analýza signálu". Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2012. http://www.nusl.cz/ntk/nusl-236491.
Texto completoQin, Xuefei. "Measurement of horses gaits using geo-sensors". Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-17769.
Texto completoCatelli, Ezio. "Representation functions in Signal Processing". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13530/.
Texto completoBechtold, Bastian [Verfasser], de Par Steven [Akademischer Betreuer] van, Jörg [Akademischer Betreuer] Bitzer y Udo [Akademischer Betreuer] Zölzer. "Pitch of Voiced Speech in the Short-Time Fourier Transform: Algorithms, Ground Truths, and Evaluation Methods / Bastian Bechtold ; Steven van de Par, Jörg Bitzer, Udo Zölzer". Oldenburg : BIS der Universität Oldenburg, 2021. http://d-nb.info/1232405213/34.
Texto completoBartůšek, Jan. "Time Frequency Analysis of ERP Signals". Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2007. http://www.nusl.cz/ntk/nusl-412769.
Texto completoEl, Gemayel Tarek. "Feasibility of Using Electrical Network Frequency Fluctuations to Perform Forensic Digital Audio Authentication". Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/24383.
Texto completoFendrychová, Michaela. "Detekce elektrického oblouku". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-241952.
Texto completoHodkiewicz, Melinda R. "The effect of partial-flow operation on the axial vibration of double-suction centrifugal pumps". University of Western Australia. School of Mechanical Engineering, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0067.
Texto completoLöfgren, Isabelle. "Interharmonic Analysis of Sustainable Energy Sources and Loads : Comparing two signal processing methods for estimation of interharmonics". Thesis, Högskolan Dalarna, Energiteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:du-34236.
Texto completoMercat, Benjamin. "Analyse temps-fréquence en mécanique cellulaire et adaptabilité du fuseau mitotique". Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S124/document.
Texto completoThe mitotic spindle ensures the correct segregation of the sister chromatids to maintain ploidy in daughter cells. The spindle comprises dynamical microtubules (alternating polymerizing and depolymerizing), a variety of molecular motors, crosslinker and the regulators. Although the molecular grounds of spindle structure is well known, the link to its functions remain elusive, calling for including the dynamics of its components and their interactions. These questions were mostly investigated by in silico or in vitro approaches. But a detailed characterizing of spindle mechanics, in physiological conditions, is missing. We propose an image processing based, non invasive, method combined to an heuristic model to measure mechanical parameters of the mitotic spindle along time. We tracked fluorescently labeled spindle pole at high temporal and spatial resolution and measured the variations of spindle length, in vivo. We computed their power density spectrum using short time Fourier transform (sliding window) — a blueprint of spindle mechanics. Such a spectrum is then fitted with a Kelvin —Voigt model with inertia (a spring, a damper, an inertial element in parallel). We validated this method by recovering the mechanical parameters over time from simulated data and calibrated it uses laser and genetically induced spinlde cut. We characterized the mitotic spindle of the one-cell embryo of nematode C. elegans. Metaphase appeared dominated by damping element, consistent with the slow spindle elongation observed. But in contrast with the common thought that a mechanism maintains the spindle length during metaphase. At anaphase onset, all three parameters collapsed, before increasing about 50s later to reach a regime where damping dominated again, suggesting the overlapping spinlde microtubules may play a minor role in early anaphase spinlde elongation. In perspective of understanding how spindle mechanics emerge of molecular players interactions, we depleted one gene per splindle sub-structure — overlapped microtubules, kinetochore microtubules, central spindle and astral microtubules. We succefully recovered some known behavior but with the augmented insight offered by our method. This method paves the way not only towards understanding the fundamentals of spindle mechanics, superseding the degenerated modeling based on the sole spindle length but also towards acounting for spindle functional robustness towards defect as polyor aneuploidy
Pyon, Okmin. "The data processing to detect correlated movement of Cerebral Palsy patient in early phase". Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/64776.
Texto completoMaster of Science
Liu, Qingling. "Pilot-induced oscillation detection and mitigation". Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7998.
Texto completoThe aim of this thesis is to develop a real time PIO detection and mitigation system that consists of a detector based on short time Fourier transform(STFT) and autoregressive model(ARX) with exogenous inputs, together with an adaptive controller based mitigation system. The system not only detects the traditional PIO characteristics but also focuses on the trend of pilot behaviour by calculating the rate of change in the open loop crossover frequency. In the detection system, a sliding windowed STFT method was applied to identify the frequency and phase characteristics of the system via processing the signal of pilot input and aircraft state. An ARX model was also applied to get the rate of change of the crossover frequency. After detection, a PIO cue was shown on the primary flight display. A scheduled gain controller was coupled to provide PIO mitigation by varying stick input gain. Compensatory and tracking tests for the evaluation of this system were performed using a quasi-linear Boeing-747 aircraft model including nonlinear command gearing and actuator rate-limiting. Bandwidth and Gibson criteria were used to design PIO prone control laws for system evaluation experiments. Results from PIO tests conducted on desktop PCs were presented. These were analyzed and compared with those obtained from implementing the Real-time Oscillation Verifier module available in literature.
Tuleja, Peter. "Využití Hilbert Huangovy transformace pro analýzu nestacionárních signálů z fyzikálních experimentů". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220614.
Texto completoDias, Fernando Luis. "Um esquema de Fourier local para análise tempo-frequência de sinais não-estacionários aplicado a ruído eletroquímico". Universidade do Estado do Rio de Janeiro, 2014. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=7720.
Texto completoSinais diversos estão presentes em nosso cotidiano, assim como nas medidas realizadas nas atividades de ciência e tecnologia. Dentre estes sinais, tem grande importância tecnológica aqueles associados à corrosão de estruturas metálicas. Assim, esta tese propõe o estudo de um esquema local de transformada de Fourier janelada, com a janela variando em função da curtose, aplicada a sinais de ruído eletroquímico. A curtose foi avaliada nos domínios do tempo e da frequência e processada pelo programa desenvolvido para esse fim. O esquema foi aplicado a sinais de ruído eletroquímico dos aços UNS S31600, UNS G10200 e UNS S32750 imersos em três soluções: FeCl3 0,1 mol=L (cloreto férrico), H2SO4 5%(ácido sulfúrico) e NaOH 0,1%(hidróxido de sódio). Para os aços inoxidáveis, estas soluções promovem corrosão localizada, uniforme e passivação, respectivamente. Visando testar o desempenho do esquema de Fourier desenvolvido, testes foram realizados utilizando-se inicialmente sinais sintéticos e em seguida sinais de ruído eletroquímico. Notou-se que os sinais têm características de não-estacionaridade e a maior parte da energia está presente em baixa frequência. Os intervalos de tempo e de frequência onde se concentra a maior parte da energia do sinal foram correlacionados. Para os picos máximos dos sinais de potencial e corrente obtidos de amperimetria de resistência nula, a correlação entre eles foi baixa, independente da forma de corrosão presente. Conclui-se que o método se adaptou bastante bem às características locais do sinal eletroquímico permitindo o monitoramento dos espectros tempo-frequência. O fato de ser sensível às características locais do sinal permite analisar aspectos dos sinais que do modo clássico não podem ser diretamente processados. O método da transformada de Fourier janelada variável (Variable Short-Time Fourier Transform - VSTFT) adaptou-se muito bem no monitoramento dos sinais originados de potencial de circuito aberto e amperimetria de resistência nula.
Several signals are present in our daily lives, as well as in the measurements from scientific and technological procedures. Among these signals, it has great technological importance those associated with corrosion of metallic structures. Thus, this thesis considers a local windowed Fourier transform, varying according to the kurtosis of signals, applied to electrochemical noise. The kurtosis was assessed in the kurtosis of the time and frequency domains and evaluated by the software developed for this purpose. The scheme has been applied to electrochemical noise signals of UNS S31600, UNS G10200 and UNS S32750 steels immersed in three solutions: FeCl3 0.1 mol=L (ferric chloride), H2SO4 5 % (sulfuric acid) and NaOH 0.1 % (sodium hydroxide). For stainless steels, these solutions cause localized corrosion, uniform corrosion and passivation, respectively. To test the performance of the proposed Fourier scheme, tests were conducted initially using synthetic signal and then electrochemical noise signals. It is worth noticing that the signals have non-stationary characteristics and most part of its energy is present at low frequency. The time and frequency intervals which concentrate most part of the energy of the signal were correlated. For the maximum peaks of the potential and current signals obtained by zero resistance ammeter, the correlation between them was low, regardless of the form of present corrosion. We conclude that the method is well adapted to the local features of the electrochemical signal allowing the monitoring of time-frequency spectograms. As the method is sensitive to the local features of the sign, it allows to analyse signals that by the classic approach can not be directly processed. The windowed Fourier transform (Variable Short-Time Fourier Transform - VSTFT) adapted very well in monitoring of the signals originated by open circuit potential and zero resistance ammeter.
Kasaei, Shohreh. "Fingerprint analysis using wavelet transform with application to compression and feature extraction". Thesis, Queensland University of Technology, 1998. https://eprints.qut.edu.au/36053/7/36053_Digitised_Thesis.pdf.
Texto completoPřikryl, Petr. "Porovnání úspěšnosti vícekanálových metod separace řečových signálů". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-217519.
Texto completoAkinci, Berna. "Realization Of A Cue Based Motor Imagery Brain Computer Interface With Its Potential Application To A Wheelchair". Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612607/index.pdf.
Texto completoRodrigues, Letícia Caldeira Pereira. "Técnicas para a detecção, classificação e localização no tempo das variações de tensão de curta e longa duração". Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-04032009-150846/.
Texto completoThe objectives of this work are going since the presentation of the researches related to the analyses of power quality (PQ) disturbances through the proposal of an algorithm based on several tools for detection and location in time, as well as the automatic classification of these phenomena. It is proposed to determine not only the initial and the end of a unique event, but all the n possible disconformities in the waveform that can exist or occur in the data file registered data in analyses. As the differential of this research, from the location in time of the alteration/discontinuities in the waveforms, it was possible to obtain data windows with flexible sizes. So, several events on the signal were evaluated, as well as their specific timeduration. For this purpose, the Wavelet transform (WT) was used to reach the detection and localization in time of the waveform alterations. For the event classification, the TW, the Fourier transform (FT) and the Root Mean Square (RMS) value were used. The data window flexibility allowed an appropriate choice of which tool could be better used in the classification task. As implemented, each one of these tools presented an answer, and the final answer was obtained by using a logic decision module. To validate the study, some situations of disturbances were characterized using a real distribution system, implemented and simulated applying the ATP (Alternative Transients Program) software. The results were excellent in such a way for detection and localization in time, as well as for the automatic classification and estimation of the magnitude and the event duration.
Kaphle, Manindra R. "Analysis of acoustic emission data for accurate damage assessment for structural health monitoring applications". Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/53201/1/Manindra_Kaphle_Thesis.pdf.
Texto completoByers, Russell F. Carleton University Dissertation Engineering Electrical. "Modification of short-time fourier transformed speech magnitude using image filter operators". Ottawa, 1991.
Buscar texto completoKerbal, Sofiane. "Development of new criteria for train detection and evaluation in critical conditions". Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-253201.
Texto completoTågsignalsystem är väsentliga för att garantera trafikstyrning och säkerhet i tågnätet.Spåren är indelade i sektioner, s.k. block, som övervakas med fasta signalinstallationer.För att hindra tåg från att krocka, tillåts bara ett tåg i taget per block. IFrankrike (och de flesta andra europeiska länder), detekteras tågen med en elektriskspårkrets som består av en sändare och en mottagare som är installerad bredvidspåret och ansluten till rälsen. När inget tåg finns på spåret, flyter en elektrisk signalfrån sändaren till mottagaren via spåret. När ett tåg anländer, kortsluts kretsenav hjulaxeln och signalen försvinner från mottagaren. Minskningen i signalstyrkaanvänds för att detektera tåget. Denna metod sällan misslyckas i tågnätet, men iovanliga fall kan det uppstå farliga situationer. I detta examensarbete utvärderasnya detektionsmetoder, som har föreslagits i tidigare studier, på signaler som haruppmätts under förhållanden med dålig kontakt mellan hjul och spår. Tre olika metoderhar testats, en i tidsdomänen och två i frekvensdomänen. Tidsdomänsmetodenjämför kortvarig och långvarig statistik för den mottagna signalen. I spektrum förden mottagna signalen, har man observerat en förändring runt den tredje övertonen,samt detektering av frekvenstoppar vid tredje övertonen. De erhållna resultatenvisar på förbättrad detektering när de nya och existerande kriterierna kombineras.
Hertzog, P. E. y G. D. Jordaan. "Wavelets and short time fourier transforms on ultrasonic doppler signals for pregnancy determination in sheep". Interim : Interdisciplinary Journal, Vol 5, Issue 1: Bloemfontein : Central University of Technology, Free State, 2006. http://hdl.handle.net/11462/414.
Texto completoThe reproductive status of animals is of utmost importance to the modern farmer. Decisions concerning the management of the flock are influenced by the knowledge of the percentage of animals that are pregnant at any specific time. The aim of the project was to gain knowledge for the development of an instrument that is affordable and with which a farmer can do pregnancy determination himself/herself, thereby enabling him/her to make the correct management decisions. Experimental data were obtained from pregnant Dorper ewes with the aid of a portable Doppler instrument. Using real data as input, simulations of Wavelet and Short Time Fourier Transforms (STF) were done in MathCAD. In the simulations known levels of noise were added to the Doppler signals. Satisfactory results were obtained from the simulations of Wavelet Transforms. In the simulation of the Wavelet Transforms, signals with a SNR of -6.5 dB were successfully identified. It can thus be concluded that Wavelet Transforms can be used successfully for the detection of the fetal heartbeat in noisy ultrasonic Doppler signals.
Kubišta, Ladislav. "Mikrofonní pole malých rozměrů pro odhad směru přicházejícího zvuku". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413257.
Texto completoHanzálek, Pavel. "Praktické ukázky zpracování signálů". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-400849.
Texto completoLin, Chien-Ying y 林謙盈. "The Study of Hopping Short Time Fourier Transform". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/45484541282306465188.
Texto completo國立臺北大學
通訊工程研究所
103
In the signal processing, we usually use Fourier transform the signal from time domain to frequency domain to analyze frequency. Before this study, Fourier transform already have some algorithm ex: Short time Fourier transform (STFT) and fast Fourier transform (FFT). Usually when we compute the Fourier transform, we will hop some time interval and compute the signal again. It will waste lots of resource during recomputing. In this study, we propose three efficient method of computing the hopping short-time Fourier transform (HSTFT). The idea is using the iterative equation to reduce the computation and prove the error is bounded. These three methods have different pros and cons to apply in different condition. Among the algorithms, FFT can only analyze the frequency which is an integer multiple of 2π/N but FFT just need less computation; STFT can analyze arbitrary frequency but have greater computational complexity. We will discuss these issues in the study.
Lai, Hsin-Liang y 賴信良. "Mixed signal separation based on fractional Fourier and short-time Fourier transform analysis". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/d74x7z.
Texto completo國立雲林科技大學
電機工程系
102
In this thesis, the methods for mixed signal separation based on fractional Fourier and short-time Fourier transform analysis are proposed. In the first part, we determine the best order of fractional Fourier transform for separating the mixed signals in a theoretical approach. Then, the results based on the Gaussian fitting approach reported in our previous work are validated. In the second part, consider that the multi-component Gaussian linear chirp signals may overlap in a single fractional order. The separated signals may have low correlation coefficients with their original versions. Because the spectrogram of a Gaussian linear chirp signal is elliptically distributed, we use a simplex downhill search method to obtain the spectral distribution of each signal and reconstructed the signal using the short time inverse Fourier transform. In the third part, we analyze the best order of fractional Fourier transform of the circular fringe pattern in a theoretical approach. We propose an iterative approach to search for the best fractional order by recording the maximum projection of fractional Fourier transform of signals. Then we search for the best order with a local maximum through a differential operation, and find center point of the circular fringe pattern by using the spatial filtering process. The results show that the parameters of reconstructed circular fringe pattern are close to that of the original one.
Lei, Ieok-Pan y 李躍斌. "Addendum of Missing Groundwater Levels data Using Short-Time Fourier Transform". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/2yjx7d.
Texto completo國立交通大學
土木工程系所
105
Groundwater plays an important role on regional water supply, and observation wells are critical for groundwater related analysis and management. In Taiwan, a national wise groundwater observation network was completed in 2008 and a huge amount of groundwater levels data were collected. However, because of the uncertainty of data collecting instruments and wells maintenance, data miss is unavoidable. To addendum the missing groundwater levels data, this study developed a novel data addendum procedure based on the Linear Regression (LR) and Short-Time Fourier Transform (STFT). The proposed novel procedure can preserve the data features in time domain and frequency domain. The proposed method consists of three steps. The first step is to estimate the missing daily data by using a LR model based on the neighboring well data that has the highest correlation with the well data to be addendum. The process was expected to preserve the low frequency variation of the groundwater table below 1 cycle/week. The second step is to transform the time series data to be addendum into frequency domain via STFT. The resulting spectrum will have missing segment due to the missing data. The third step is to completed the spectrum and obtains the complete groundwater level data. To addendum the spectrum, the missing spectral segment was recovered by jointing the low frequency portion of the interpolated daily data and the high frequency part of the original data to be addendum. The complete groundwater level data was obtained by using Inversed STFT to the addendum spectrum. The proposed methodology was applied to addendum the groundwater levels data in northern part of Chianan Plain and the result shows that the addendum data can effectively preserve the data features in both time domain and frequency domain. The methodology can be applied to addendum other hydrological time series data to allow the application of data driven analysis.
Tsao, Chieh-Yu y 曹介羽. "Repeat Regions Detection of DNA Sequences by Short Time Fourier Transform". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/74485163299505650062.
Texto completo國立臺灣海洋大學
通訊與導航工程系
95
Abstract Stimulated by the biotechnology revolution and the achievement of the Human Genome Project, the analysis of DNA sequence is more and more interesting and attracting. And finding repetitive sequences in DNA is of particular interest in biology due to their role in genetic diseases, human gene mapping, evolution, and many other important and interesting applications. In the face of such a question, it is urgent and far challenging to develop approaches to analyze the complex biological functions of DNA repeated sequence. For DNA sequences analysis, it is of great importance to find the position of DNA repeated sequences. The main purpose of this thesis is to develop efficient algorithms based on digital signal processing techniques such as the DFT, STFT, and Dot-matrix to find the DNA repeated sequences. At the first, structure and fundamental characteristic of the repeat sequence will be introduced. The main characteristic frequency which is the reciprocal of the repeated pattern length will be derived by the FFT. The main characteristic frequency will be incorporated into the short-time Fourier transform such that the repeated sequence locations can be clearly identified as distinct peaks (or colors) in the spectrum. Then a mixed method based on dot-matrix and auto-correlation algorithms will be employed to detect the repeat of the DNA sequences. Furthermore, we adopt the modified particle swarm optimization (MPSO) algorithm to look for the repeated regions of the DNA sequence. The method has a pretty good result to inter-spread repeat sequence. Finally, we take some datasets from the National Center for Biotechnology Information (NCBI) for illustrating the effectiveness of the proposed algorithms.
FANG, ZHEN-HONG y 方振鴻. "Signal analysis by short-time fourier transform and pseudo wigner distribution". Thesis, 1989. http://ndltd.ncl.edu.tw/handle/45034471683607392574.
Texto completoJONES, DOUGLAS LLEWELLYN. "A STUDY OF WINDOWS FOR THE SHORT-TIME FOURIER TRANSFORM (WIGNER, TIME, FREQUENCY, MATCHED)". Thesis, 1986. http://hdl.handle.net/1911/13170.
Texto completoWei, Chih-Chao y 魏志兆. "Automatic Heart Sound Analysis with Short-Time Fourier Transform and Support Vector Machines". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/fg63w3.
Texto completo國立臺灣師範大學
應用電子科技研究所
97
The heart disease has become the second cause of death, and most of heart diseases result from heart valve disorders. skilled cardiologists probe heart sounds by electronic stethoscope through human ears, but interpretation of heart sounds is a very special skill which is quite difficult to teach in a structured way. Because of this reason, automatic heart sound analysis in computer systems would be very helpful for medical staff. This paper presents a complete heart sound analysis system covering from the segmentation of beat cycles to the final determination of heart conditions. The kernels of heart beat cycle segmentation and recognition are based on autocorrelation, short-time Fourier transform, and support vector machines. The experiments are done with a public heart sound database released by Texas Heart Institute, with very promising recognition rate achieved.
LI, MENG-SIAN y 李孟賢. "Study and Analysis of Short-Time Fourier Transform for Differential Frequency Hopping Sequences". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/65130131616363058393.
Texto completo中華科技大學
電子工程研究所碩士班
98
DFH (differential frequency hopping, DFH) communications system is to use frequency hopping, and its relevance to carry around like to send the data bits. Comparison of the system include the frequency shift key technology design G function, frequency detection, and received a series detect the state of the path. In this paper, the frequency detected by the receiver-side short-time Fourier transform (STFT) frequency hopping sequence detection technology as the basis of frequency hopping signals to do the original analysis to confirm the correctness of system design; to make further additive white Gaussian noise (AWGN), multipath effects, fading channel (fading channel) and other environmental, all simulation data under the situation of frequency detection and data recovery. In this paper the design of the detection process in the final simulation results show, STFT in AWGN, multipath ISI (inter symbol interference, ISI) and fading channels can really under the influence of the frequency of screening in the first phase will be transmitter sent by the frequency selected. However, the simulation found that the information system restore point the real difficulty is to STFT, the frequency of the selected sequence to be screened; with the transfer matrix of the screening method, if want to have good performance, in fact, there are many conditions or factors that are closely linked with the transfer matrix structure; such as the size of transfer matrix, fan-out state of the matrix coefficients, these parameters will be using transfer matrix G frequency filter function caused by a misjudgment.
Lo, Fang-Chun y 羅芳鈞. "Application of Short-Time Fourier Transform for Real-Time Surface Damage Detection of Wind Turbine Blades". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/tgpw7x.
Texto completo國立臺灣大學
工程科學及海洋工程學研究所
105
The main idea of this research is to establish a complete system for surface damage detection of wind turbine blades. Because of long-term exposure in an extreme environment, the damage on wind turbine’s components is inevitable, and mostly on the blades. Thus, wind turbine requires regular detection and maintenance to avoid safety issues and financial loses. The traditional assessment for surface damage detection of wind turbine blades is to evaluate the operation noise by a professional using his ears to listen. Sometimes, judging by the professional’s personal experience, he has to stop the wind turbine and execute the detection from the above to the blades. Not only does it demand special skills, it is also accompanied with high risk caused by the extreme environment wind turbine was built at. So, it is very dangerous and inconvenient for us if we must count on ears or climbing skills to conduct the assessment, not to mention the recent arising of offshore wind turbine. With the number of global wind turbine rapidly increases and develops, establishing a complete system for surface damage detection of wind turbine blades becomes more and more essential. This research using time-frequency analysis short-time Fourier transform from MATLAB to analyze the blades’ noise while operation, by placing microphone under the wind turbine and recording. First, to build a normal model as foundation for comparison, we put recordings of a wind turbine without abnormal sound into time-frequency analysis and applying it to methods like marginal spectrum, decibel transformation and polynomial regression. Then, based on the normal model, we defined the formula this research shows, as an indicator to determine if the blades are damaged. Finally, we can also define the optimal damage threshold by utilizing the receiver operating characteristic curve and calculating the area under the curve. This new way for detection allows us to receive blades’ damage reports by computer’s automatically diagnosis without affecting or stopping the wind turbine’s operation. This research’s detection results are testified by actual photo from wind turbine’s blades. Hopefully, it can be applied as wind turbine’s health detection systems in the future.
RIBA, LUIGI. "Multi-Dimensional Stockwell Transforms and Applications". Doctoral thesis, 2014. http://hdl.handle.net/2318/142144.
Texto completoLiao, Chien-Cheng y 廖乾丞. "Application of Short Time Fourier Transform for Improving the FTP Phase Recovery in case of Local Large Phase Gradient". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/rxge2r.
Texto completo國立中興大學
機械工程學系所
104
The propose of this paper is solving the problem that we can’t extract the precise phase at the high phase gradient when using the traditional Fringe Pattern Profilometry (FPP) and Fourier Transform Profilometry (FTP).With the idea of the Short Time Fourier Transform (STFT), we can find the partial frequency of the fringe in the original, messy spectrum. Using the inverse mapping, the original, deform fringe-pattern could be translated to the relative phase of the reference plane according to the phase of the first filtering. After the inverse mapping, we can use the Papoulis-Gerchberg algorithm to fill the areas which have no data, so it would help us to examine the precise which are found of the filtering in the frequency domain. If the data is not complete, we could reduce the analysis window which is used in the STFT. Keep repeating this step, until the precise which are modulated by the contour of the surface are eliminated. The experimental results display the precise which are modulated by the contour of the surface of the high fringe-diversification in the traditional FTP could be find and restore successfully by using the inverse mapping and the P-G algorithm to search the position of the filtering repeatedly.