Dissertations / Theses on the topic 'Signals'
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1
Li, Jian. "Array signal processing for polarized signals and signals with known waveforms /." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487687485808063.
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Saruwatari, Hiroshi. "BLIND SIGNAL SEPARATION OF AUDIO SIGNALS." INTELLIGENT MEDIA INTEGRATION NAGOYA UNIVERSITY / COE, 2006. http://hdl.handle.net/2237/10406.
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Ghaderi, Foad. "Signal processing techniques for extracting signals with periodic structure : applications to biomedical signals." Thesis, Cardiff University, 2010. http://orca.cf.ac.uk/55183/.
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In this dissertation some advanced methods for extracting sources from single and multichannel data are developed and utilized in biomedical applications. It is assumed that the sources of interest have periodic structure and therefore, the periodicity is exploited in various forms. The proposed methods can even be used for the cases where the signals have hidden periodicities, i.e., the periodic behaviour is not detectable from their time representation or even Fourier transform of the signal. For the case of single channel recordings a method based on singular spectrum anal ysis (SSA) of the signal is proposed. The proposed method is utilized in localizing heart sounds in respiratory signals, which is an essential pre-processing step in most of the heart sound cancellation methods. Artificially mixed and real respiratory signals are used for evaluating the method. It is shown that the performance of the proposed method is superior to those of the other methods in terms of false detection. More over, the execution time is significantly lower than that of the method ranked second in performance. For multichannel data, the problem is tackled using two approaches. First, it is assumed that the sources are periodic and the statistical characteristics of periodic sources are exploited in developing a method to effectively choose the appropriate delays in which the diagonalization takes place. In the second approach it is assumed that the sources of interest are cyclostationary. Necessary and sufficient conditions for extractability of the sources are mathematically proved and the extraction algorithms are proposed. Ballistocardiogram (BCG) artifact is considered as the sum of a number of independent cyclostationary components having the same cycle frequency. The proposed method, called cyclostationary source extraction (CSE), is able to extract these components without much destructive effect on the background electroencephalogram (EEG)
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Östlund, Nils. "Adaptive signal processing of surface electromyogram signals." Doctoral thesis, Umeå universitet, Strålningsvetenskaper, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-743.
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Electromyography is the study of muscle function through the electrical signals from the muscles. In surface electromyography the electrical signal is detected on the skin. The signal arises from ion exchanges across the muscle fibres’ membranes. The ion exchange in a motor unit, which is the smallest unit of excitation, produces a waveform that is called an action potential (AP). When a sustained contraction is performed the motor units involved in the contraction will repeatedly produce APs, which result in AP trains. A surface electromyogram (EMG) signal consists of the superposition of many AP trains generated by a large number of active motor units. The aim of this dissertation was to introduce and evaluate new methods for analysis of surface EMG signals. An important aspect is to consider where to place the electrodes during the recording so that the electrodes are not located over the zone where the neuromuscular junctions are located. A method that could estimate the location of this zone was presented in one study. The mean frequency of the EMG signal is often used to estimate muscle fatigue. For signals with low signal-to-noise ratio it is important to limit the integration intervals in the mean frequency calculations. Therefore, a method that improved the maximum frequency estimation was introduced and evaluated in comparison with existing methods. The main methodological work in this dissertation was concentrated on finding single motor unit AP trains from EMG signals recorded with several channels. In two studies single motor unit AP trains were enhanced by using filters that maximised the kurtosis of the output. The first of these studies used a spatial filter, and in the second study the technique was expanded to include filtration in time. The introduction of time filtration resulted in improved performance, and when the method was evaluated in comparison with other methods that use spatial and/or temporal filtration, it gave the best performance among them. In the last study of this dissertation this technique was used to compare AP firing rates and conduction velocities in fibromyalgia patients as compared with a control group of healthy subjects. In conclusion, this dissertation has resulted in new methods that improve the analysis of EMG signals, and as a consequence the methods can simplify physiological research projects.
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Östlund, Nils. "Adaptive signal processing of surface electromyogram signals /." Umeå : Department of Radiation Sciences, Umeå University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-743.
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Palekar, Trishul Ajit. "Signal optimization at isolated intersections using pre-signals." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4279.
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This research proposes a new signal operation strategy aimed at efficient utilization of
green time by cutting down on the start up and response loss times. The idea is to have a
"pre-signal" on each main approach a few hundred feet upstream of the intersection in
addition to the main intersection signal, which is coordinated with the pre-signal. The
offset between the main and pre-signal ensures that the majority of start up losses does
not occur at the main signal. The benefits of the system under various traffic conditions
were evaluated based on analysis of the queue discharge process and Corridor
Simulation (CORSIM) study. The proposed measure should reduce the travel time and
total control delay for the signalized network.
To attain the objective the following two studies were undertaken:
1. Development of a queue discharge model to investigate the expected benefits of
the system.
2. Simulation of the system: In the second part of the research, the proposed
strategy was tested using CORSIM to evaluate its performance vis-ÃÂ -vis the
baseline case.
The queue discharge model (QDM) was found to be linear in nature in contrast to prior
expectations. The model was used to quantify the benefits obtained from the pre-signal
system. The result of this analysis indicated that the proposed strategy would yield
significant travel time savings and reductions in total control delay. In addition to the QDM analysis, CORSIM simulations were used to code various
hypothetical scenarios to test the concept under various constraints and limitations. As
per expectations, it was found that the system was beneficial for high demand levels and
longer offsets. The upper limit on offsets was determined by visual observation of
platoon dispersion and therefore the maximum offset distance was restricted to 450 feet.
For scenarios where split phasing was used, the break even point in terms of demand
level was found to be 2500 vph on a three lane approach, whereas that for a lag-lag type
of phasing strategy was found to be 1800 vph, also on a three lane approach.
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Chan, M. K. "Adaptive signal processing algorithms for non-Gaussian signals." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269023.
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Bland, Denise. "Alias-free signal processing of nonuniformly sampled signals." Thesis, University of Westminster, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322992.
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Park, Subok. "Signal detection with random backgrounds and random signals." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280729.
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In this dissertation we explore theoretical and computational methods to investigate Bayesian ideal observers for performing signal-detection tasks. Object models are used to take into account object variability in image backgrounds and signals for the detection tasks. In particular, lumpy backgrounds (LBs) and Gaussian signals are used for various paradigms of signal-detection tasks. Simplified pinhole imaging systems in nuclear medicine are simulated for this work. Markov-chain Monte Carlo (MCMC) methods that estimate the ideal observer test statistic, the likelihood ratio, for signal-known-exactly (SKE) tasks, where signals are nonrandom, are employed. MCMC methods are extended to signal-known-statistically (SKS) tasks, where signals are random. Psychophysical studies for the SKE and SKS tasks using non-Gaussian and Gaussian distributed LBs are conducted. The performance of the Bayesian ideal observer, the human observer, and the channelized-Hotelling observer for the SKE and SKS tasks is compared. Human efficiencies for both the SKE tasks and SKS tasks are estimated. Also human efficiencies for non-Gaussian and Gaussian-distributed LBs are compared for the SKE tasks. Finally, the theory of the channelized-ideal observer (CIO) is introduced to approximate the performance of the ideal observer by the performance of the CIO in cases where the channel outputs of backgrounds and signals are non-Gaussian distributed. Computational approaches to estimate the CIO are investigated.
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Hannaske, Roland. "Fast Digitizing and Digital Signal Processing of Detector Signals." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-27888.
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A fast-digitizer data acquisition system recently installed at the neutron time-of-flight experiment nELBE, which is located at the superconducting electron accelerator ELBE of Forschungszentrum Dresden-Rossendorf, is tested with two different detector types. Preamplifier signals from a high-purity germanium detector are digitized, stored and finally processed. For a precise determination of the energy of the detected radiation, the moving-window deconvolution algorithm is used to compensate the ballistic deficit and different shaping algorithms are applied. The energy resolution is determined in an experiment with γ-rays from a 22Na source and is compared to the energy resolution achieved with analogously processed signals. On the other hand, signals from the photomultipliers of barium fluoride and plastic scintillation detectors are digitized. These signals have risetimes of a few nanoseconds only. The moment of interaction of the radiation with the detector is determined by methods of digital signal processing. Therefore, different timing algorithms are implemented and tested with data from an experiment at nELBE. The time resolutions achieved with these algorithms are compared to each other as well as to reference values coming from analog signal processing. In addition to these experiments, some properties of the digitizing hardware are measured and a program for the analysis of stored, digitized data is developed. The analysis of the signals shows that the energy resolution achieved with the 10-bit digitizer system used here is not competitive to a 14-bit peak-sensing ADC, although the ballistic deficit can be fully corrected. However, digital methods give better result in sub-ns timing than analog signal processing.
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Case, David Robert. "Real-time signal processing of multi-path video signals." Thesis, University of Salford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334170.
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Haghighi-Mood, Ali. "Analysis of phonocardiographic signals using advanced signal processing techniques." Thesis, University of Sussex, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321465.
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Lin, Junne Lung. "Use of combined signals for reactor shutdown signal validation." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/33515.
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Hannaske, Roland. "Fast Digitizing and Digital Signal Processing of Detector Signals." Forschungszentrum Dresden-Rossendorf, 2009. https://hzdr.qucosa.de/id/qucosa%3A21615.
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A fast-digitizer data acquisition system recently installed at the neutron time-of-flight experiment nELBE, which is located at the superconducting electron accelerator ELBE of Forschungszentrum Dresden-Rossendorf, is tested with two different detector types. Preamplifier signals from a high-purity germanium detector are digitized, stored and finally processed. For a precise determination of the energy of the detected radiation, the moving-window deconvolution algorithm is used to compensate the ballistic deficit and different shaping algorithms are applied. The energy resolution is determined in an experiment with γ-rays from a 22Na source and is compared to the energy resolution achieved with analogously processed signals. On the other hand, signals from the photomultipliers of barium fluoride and plastic scintillation detectors are digitized. These signals have risetimes of a few nanoseconds only. The moment of interaction of the radiation with the detector is determined by methods of digital signal processing. Therefore, different timing algorithms are implemented and tested with data from an experiment at nELBE. The time resolutions achieved with these algorithms are compared to each other as well as to reference values coming from analog signal processing. In addition to these experiments, some properties of the digitizing hardware are measured and a program for the analysis of stored, digitized data is developed. The analysis of the signals shows that the energy resolution achieved with the 10-bit digitizer system used here is not competitive to a 14-bit peak-sensing ADC, although the ballistic deficit can be fully corrected. However, digital methods give better result in sub-ns timing than analog signal processing.
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Snipes, Elizabeth Ashmore. "Mixed signals." Connect to this title online, 2007. http://etd.lib.clemson.edu/documents/1202499451/.
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Rowe, Candida L. "Multicomponent signals." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299417.
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Klingaman, Dane. "Private signals." Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1571858.
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Using collage and other material processes, I transform the iconic image into a more complex reading. By appropriating found images within a specific urban area, my work exposes particular histories of class discrepancy. Filtered through my personal experiences, narratives are formed using signifiers like flags, pidgin languages, and professional sports. Pictorially, I use the grid to reference the layout of the dense urban environment. This formal structure is capable of hosting a range of disparate images and mediums. My exhibition Private Signals refers to the development of personal relationships that are formed through the manipulation of public images.
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Mabrouk, Mohamed Hussein Emam Mabrouk. "Signal Processing of UWB Radar Signals for Human Detection Behind Walls." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/31945.
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Non-contact life detection is a significant component of both civilian and military rescue applications. As a consequence, this interest has resulted in a very active area of research. The primary goal of this research is reliable detection of a human breathing signal. Additional goals of this research are to carry out detection under realistic conditions, to distinguish between two targets, to determine human breathing rate and estimate the posture. Range gating and Singular Value Decomposition (SVD) have been used to remove clutter in order to detect human breathing under realistic conditions. However, the information of the target range or what principal component contains target information may be unknown. DFT and Short Time Fourier Transform (STFT) algorithms have been used to detect the human breathing and discriminate between two targets. However, the algorithms result in many false alarms because they detect breathing when no target exists. The unsatisfactory performance of the DFT-based estimators in human breathing rate estimation is due to the fact that the second harmonic of the breathing signal has higher magnitude than the first harmonic. Human posture estimation has been performed by measuring the distance of the chest displacements from the ground. This requires multiple UWB receivers and a more complex system. In this thesis, monostatic UWB radar is used. Initially, the SVD method was combined with the skewness test to detect targets, discriminate between two targets, and reduce false alarms. Then, a novel human breathing rate estimation algorithm was proposed using zero-crossing method. Subsequently, a novel method was proposed to distinguish between human postures based on the ratios between different human breathing frequency harmonics magnitudes. It was noted that the ratios depend on the abdomen displacements and higher harmonic ratios were observed when the human target was sitting or standing. The theoretical analysis shows that the distribution of the skewness values of the correlator output of the target and the clutter signals in a single range-bin do not overlap. The experimental results on human breathing detection, breathing rate, and human posture estimation show that the proposed methods improve performance in human breathing detection and rate estimation.
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Krishnan, Sridhar. "Adaptive signal processing techniques for analysis of knee joint vibroarthrographic signals." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0016/NQ47897.pdf.
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Andrikogiannopoulos, Nikolas I. "RF phase modulation of optical signals and optical/electrical signal processing." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/42930.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 125-127).
Analog RF phase modulation of optical signals has been a topic of interest for many years, mainly focusing on Intensity Modulation Direct Detection (IMDD). The virtues of coherent detection combined with the advantages of Frequency Modulation, however, have not been explored thoroughly. By employing Frequency Modulation Coherent Detection (FMCD), the wide optical transmission bandwidth of optical fiber can be traded for higher signal-to-noise performance. In this thesis, we derive the FM gain over AM modulation -- the maximum achievable signal-to-noise ratio (by spreading the signal's spectrum) for specific carrier-to-noise ratio. We then employ FMCD for a scheme of remote antennas for which we use optical components and subsystem to perform signal processing such as nulling of interfering signals. The performance of optical processing on different modulation schemes are compared, and some important conclusions are reported relating to the use of conventional FMCD, FMCD with optical discriminator (FMCD O-D), and IMDD. Specifically, the superiority of conventional FMCD is shown; and, on the other hand, the inferiority of FMCD O-D is shown (same performance as IMDD) because of the use of an O-D. Finally, the remote antenna scheme is generalized for N antennas and N users.
by Nikolas I. Andrikogiannopoulos.
S.M.
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Atherton, Philip James. "Signal transduction in skeletal muscle mediating responses to phenotype altering signals." Thesis, University of Central Lancashire, 2005. http://clok.uclan.ac.uk/8584/.
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Skeletal muscle phenotype, size and function respond to exercise, disease and ageing. The aim of this thesis was to investigate the signal transduction pathways responsible for selected skeletal muscle phenotype and size changes. Myostatin, recently identified as a negative regulator of muscle mass was exposed at 10 ng ml 4 to C2C12 cells, and using cDNA genome-wide profiling, was shown to act as a transcriptional suppressor. Furthermore, in these cells myostatin significantly (n8, p<0.05) reduced phosphorylation of components in the P1-3K pathway: PKB Ser473 -30 %, mTOR Ser2448 -50 %, p70 S6K Thr389 -60 %, whereas 4E-BP1 Thr37/46 remained unaffected. These data provide insights in to the mechanisms by which myostatin controls muscle mass, through negatively affecting transcription and translation. Differences in the concentrations of signalling proteins often alter cellular function and phenotype, as is evident from numerous heterozygous knock-out models. Whilst the levels of metabolic enzymes differ between fibre types, and are regulable by exercise, it is not known if this is also true of signal transduction proteins. Therefore, it was hypothesised that the relative levels of signalling proteins implicated in the adaptation to exercise in both fast rat extensor digitorum longus (EDL; 3% type I fibres) and slow Soleus (84% type I fibres) would be systematically different. Secondly, it was hypothesised that following 6 weeks of chronic electrical stimulation (CMNS) where the EDL undergoes a fast-to-slow transformation, the relative signalling protein concentrations between control EDL/stimulated EDL would mirror the differences shown in control EDL/Soleus. Finally, that CMNS would induce chronic signalling to produce, and maintain a slower phenotype. Western blots revealed that the concentrations of some proteins such as Calcineurin (2.6-fold) and p38 MAPK (1.36-fold) were higher in EDL, whilst others such as PGC-la (1.4-fold); and NFkB (3-fold) (all n=4, pc0.05) were higher in Soleus. CMNS of EDL also led to changes in protein levels between control EDL/stimulated EDL: AMPK which is higher in Soleus was actually 1.4-fold lower following stimulation of EDL, whereas other proteins such as PGC-la moved in the direction of that of Soleus. CMNS was also able to induce chronic phosphorylation of proteins involved in fibre type and mitochondrial biogenesis, such as AMPK 4 fold, and p38 -4.5-fold. These data show that signal transduction protein concentrations vary between fast and slow muscles, presumably reflecting differences at a fibre level. Furthermore, signalling proteins are regulated by CMNS of EDL, but do not always change in the direction of slow Soleus. Chronic phosphorylation of many signalling proteins can explain the characteristic phenotypic change in response to CMNS. Resistance training stimulates adaptive protein synthesis and hypertrophy whereas endurance training induces a partial fast-to-slow fibre phenotype transformation. To simulate these conditions, isolated rat muscles were stimulated at 25 °C with either high frequency (HFS; 6 x 10 repetitions, 3 s-bursts at 100 Hz to mimic resistance training) or low frequency (LFS; 3 h at 10 Hz to mimic endurance training). HFS significantly increased myofibrillar and sarcoplasmic protein synthesis 3 h after stimulation 5.3 and 2.7-fold, respectively (n=6, p<0.05). LFS had no significant effect on protein synthesis 3 h after stimulation, but increased UCP3 mRNA 11.7-fold, whereas HFS had no significant effect on UCP3 mRNA (n6, p<0.05). Only LFS increased AMPK phosphorylation significantly at Thr172 by 2-fold and increased POC- 1 a protein to 1.3-fold of control. LFS had no effect on PICB phosphorylation but reduced TSC2 phosphorylation at Thr1462 and deactivated translational regulators. In contrast, HFS acutely increased phosphorylation of PKB at Ser473 5.3-fold and the phosphorylation of TSC2, mTOR, GSK-3j3 at PKB-sensitive sites. HFS also caused a prolonged activation of the translational regulators p70 56k, 4E-BPI, eIF2B, and eEF2 (all n=8, p<0.05). This behaviour has been termed the AMPK-PICB switch, and is hypothesised to mediate specific adaptations to endurance and resistance training, respectively. Ageing is associated with a loss of muscle mass tenned sarcopenia. Essential amino acids (EAA) are potent stimulators of muscle protein synthesis (MPS), and therefore defects in EAA-induced anabolism might affect ability to maintain muscle mass in ageing and disease. MPS and signalling responses to EAA-stimulation of 20 fasted young versus 24 elderly subjects (age 28 ± 6 and 70 ± 6; BMI 24 ± 3, 25 ± 4 kg.m 2 respectively; means ± SD) and 8 fasted elderly versus 8 elderly with type II DM (age 66 ± 3 and 70 ± 6; BMI: 25 ± 4 vs. 32 ± 2 kg.m 2, respectively means ± SD) were measured using gas combustion mass spectrometry and Western blotting methods. Basal MPS rates were indistinguishable, but the elderly displayed a reduced anabolic responsiveness of MPS to EAA, possibly due to decreased intramuscular phosphorylation after EAA, of amino acid sensing/signalling proteins mTOR, p70 S6 kinase, 4E-BPI and eIF2Bs by —50 %. This was further exacerbated in elderly with type II DM whom exhibited reduced Ser2448 phosphorylation of mTOR by —50 %, reflecting decreased downstream signalling. Associated with the anabolic deficits were — 4-fold increases in NFiB protein, the inflammation-associated transcription factor, as well as —50 % and —20 % decreases in protein expression of p70 S6K of healthy elderly and elderly with type II DM, respectively. These results suggest that the elderly are unable to mount a full anabolic response to EAA and that this blunting is further pronounced in type II DM.
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Aprea, Matthew. "A model for predicting indoor signal levels of satellite transmitted signals." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-07292009-090621/.
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Kbayer, Nabil. "Advanced Signal Processing Methods for GNSS Positioning with NLOS/Multipath Signals." Thesis, Toulouse, ISAE, 2018. http://www.theses.fr/2018ESAE0017/document.
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Les avancées récentes dans le domaine de navigation par satellites (GNSS) ontconduit à une prolifération des applications de géolocalisation dans les milieux urbains. Pourde tels environnements, les applications GNSS souffrent d’une grande dégradation liée à laréception des signaux satellitaires en lignes indirectes (NLOS) et en multitrajets (MP). Cetravail de thèse propose une méthodologie originale pour l’utilisation constructive des signauxdégradés MP/NLOS, en appliquant des techniques avancées de traitement du signal ou àl’aide d’une assistance d’un simulateur 3D de propagation des signaux GNSS. D’abord, nousavons établi le niveau maximal réalisable sur la précision de positionnement par un systèmeGNSS "Stand-Alone" en présence de conditions MP/NLOS, en étudiant les bornes inférieuressur l’estimation en présence des signaux MP/NLOS. Pour mieux améliorer ce niveau deprécision, nous avons proposé de compenser les erreurs NLOS en utilisant un simulateur 3D dessignaux GNSS afin de prédire les biais MP/NLOS et de les intégrer comme des observationsdans l’estimation de la position, soit par correction des mesures dégradées ou par sélectiond’une position parmi une grille de positions candidates. L’application des approches proposéesdans un environnement urbain profond montre une bonne amélioration des performances depositionnement dans ces conditionsRecent trends in Global Navigation Satellite System (GNSS) applications inurban environments have led to a proliferation of studies in this field that seek to mitigatethe adverse effect of non-line-of-sight (NLOS). For such harsh urban settings, this dissertationproposes an original methodology for constructive use of degraded MP/NLOS signals, insteadof their elimination, by applying advanced signal processing techniques or by using additionalinformation from a 3D GNSS simulator. First, we studied different signal processing frameworks,namely robust estimation and regularized estimation, to tackle this GNSS problemwithout using an external information. Then, we have established the maximum achievablelevel (lower bounds) of GNSS Stand-Alone positioning accuracy in presence of MP/NLOSconditions. To better enhance this accuracy level, we have proposed to compensate for theMP/NLOS errors using a 3D GNSS signal propagation simulator to predict the biases andintegrate them as observations in the estimation method. This could be either by correctingdegraded measurements or by scoring an array of candidate positions. Besides, new metricson the maximum acceptable errors on MP/NLOS errors predictions, using GNSS simulations,have been established. Experiment results using real GNSS data in a deep urban environmentshow that using these additional information provides good positioning performance enhancement,despite the intensive computational load of 3D GNSS simulation
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Perelli, Alessandro <1985>. "Sparse Signal Representation of Ultrasonic Signals for Structural Health Monitoring Applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6321/1/Perelli_Alessandro_tesi.pdf.
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Assessment of the integrity of structural components is of great importance for aerospace systems, land and marine transportation, civil infrastructures and other biological and mechanical applications. Guided waves (GWs) based inspections are an attractive mean for structural health monitoring. In this thesis, the study and development of techniques for GW ultrasound signal analysis and compression in the context of non-destructive testing of structures will be presented. In guided wave inspections, it is necessary to address the problem of the dispersion compensation. A signal processing approach based on frequency warping was adopted. Such operator maps the frequencies axis through a function derived by the group velocity of the test material and it is used to remove the dependence on the travelled distance from the acquired signals. Such processing strategy was fruitfully applied for impact location and damage localization tasks in composite and aluminum panels. It has been shown that, basing on this processing tool, low power embedded system for GW structural monitoring can be implemented. Finally, a new procedure based on Compressive Sensing has been developed and applied for data reduction. Such procedure has also a beneficial effect in enhancing the accuracy of structural defects localization. This algorithm uses the convolutive model of the propagation of ultrasonic guided waves which takes advantage of a sparse signal representation in the warped frequency domain. The recovery from the compressed samples is based on an alternating minimization procedure which achieves both an accurate reconstruction of the ultrasonic signal and a precise estimation of waves time of flight. Such information is used to feed hyperbolic or elliptic localization procedures, for accurate impact or damage localization.
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Perelli, Alessandro <1985>. "Sparse Signal Representation of Ultrasonic Signals for Structural Health Monitoring Applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6321/.
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Assessment of the integrity of structural components is of great importance for aerospace systems, land and marine transportation, civil infrastructures and other biological and mechanical applications. Guided waves (GWs) based inspections are an attractive mean for structural health monitoring. In this thesis, the study and development of techniques for GW ultrasound signal analysis and compression in the context of non-destructive testing of structures will be presented. In guided wave inspections, it is necessary to address the problem of the dispersion compensation. A signal processing approach based on frequency warping was adopted. Such operator maps the frequencies axis through a function derived by the group velocity of the test material and it is used to remove the dependence on the travelled distance from the acquired signals. Such processing strategy was fruitfully applied for impact location and damage localization tasks in composite and aluminum panels. It has been shown that, basing on this processing tool, low power embedded system for GW structural monitoring can be implemented. Finally, a new procedure based on Compressive Sensing has been developed and applied for data reduction. Such procedure has also a beneficial effect in enhancing the accuracy of structural defects localization. This algorithm uses the convolutive model of the propagation of ultrasonic guided waves which takes advantage of a sparse signal representation in the warped frequency domain. The recovery from the compressed samples is based on an alternating minimization procedure which achieves both an accurate reconstruction of the ultrasonic signal and a precise estimation of waves time of flight. Such information is used to feed hyperbolic or elliptic localization procedures, for accurate impact or damage localization.
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Xu, Su Huai. "Random analytic signals." Thesis, University of Macau, 2009. http://umaclib3.umac.mo/record=b1944056.
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Makkerh, Joe Paul Singh. "Nuclear localisation signals." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363121.
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Guest, Nicholas M. "Shorting opaque signals." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105078.
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Thesis: S.M. in Management Research, Massachusetts Institute of Technology, Sloan School of Management, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 44-47).
This study uses short interest data to show that quantitative equity investors devote more capital to firm-specific arbitrage strategies in stocks with more opaque earnings. There are also higher strategy returns in stocks with opaque earnings. Together, these results suggest that quantitative investors exploit their sophistication by trading when the firm's earnings make it more costly for other market participants to understand the future implications of a signal. The result is stronger for fundamental-based strategies such as post-earnings-announcement drift than for market-based strategies such as return momentum, suggesting that arbitrageurs shift capital from market strategies to fundamental strategies when earnings are opaque. Overall, the paper highlights the role of sophisticated quantitative investors in impounding signals that are difficult to understand into prices and suggests that the opacity of a firm's fundamentals is a key determinant of sophisticated investors' trading strategies.
by Nicholas M. Guest.
S.M. in Management Research
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Silva, João Luís Sarmento Donato dos Santos e. "Medical signals monitoring." Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/23782.
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Mestrado em Engenharia Eletrónica e TelecomunicaçõesO ritmo cardíaco, quantidade de oxigénio no sangue, a pressão arterial e o nível de glicemia são variáveis da maior importância na avaliação clínica. Das quatro variáveis, a frequência cardíaca e o nível de oxigénio no sangue são aquelas cuja aquisição é relativamente menos incómoda para o paciente. A pressão arterial é tipicamente medida com um esfigmomanómetro com o auxilio de um estetoscópio. O esfigmomanómetro é composto por uma braçadeira de tecido com uma meia manga insuflável, que é enrolada à volta dum braço ou perna do paciente. A monitorização da glicémia, muito importante em diabéticos, é efetuada com um glicosímetro. Esta medição implica sempre um incomodo processo prévio de extração de uma pequena quantidade de sangue. Mesmo os instrumentos mais recentes que obtém o valor da glicémia através da analise do fluido intersticial (colhido logo abaixo da derme) implicam uma leve picada. O projecto que aqui se propõe visa melhorar o conforto do paciente no processo de aquisição destas variáveis clinicas. Este projeto visa a realização de um sistema único que integre a monitorização das quatro variáveis referidas e que o faça da forma menos invasiva que seja possível.
Heart rate, oxygen saturation in blood, blood pressure and glicemia are variables of major importance in clinical evaluation. Of the four variables, the heart rate and oxygenation in blood are those whose acquisition is relatively less discomfortable for the patient. Blood pressure is typically measured with a sphygmomanometer with the aid of a stethoscope. The sphygmomanometer consists of a tissue cu with an in atable half sleeve, which is wrapped around an arm or leg of the patient. The monitorization of glicemia, very important in diabetics, is made with a glucometer. This measurement implies always an discomfortable process of extracting a small quantity of blood. Even the most recent instruments that obtain the value of glycemia through interstitial uid analysis (collected just below the dermis) imply a slight sting. The project proposed here aims to improve patient comfort in the process of acquisition of these clinical variables. A single system is designed that integrates the monitoring of the four variables mentioned and does so in the least invasive way possible.
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Rida, Imad. "Temporal signals classification." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMIR01/document.
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De nos jours, il existe de nombreuses applications liées à la vision et à l’audition visant à reproduire par des machines les capacités humaines. Notre intérêt pour ce sujet vient du fait que ces problèmes sont principalement modélisés par la classification de signaux temporels. En fait, nous nous sommes intéressés à deux cas distincts, la reconnaissance de la démarche humaine et la reconnaissance de signaux audio, (notamment environnementaux et musicaux). Dans le cadre de la reconnaissance de la démarche, nous avons proposé une nouvelle méthode qui apprend et sélectionne automatiquement les parties dynamiques du corps humain. Ceci permet de résoudre le problème des variations intra-classe de façon dynamique; les méthodes à l’état de l’art se basant au contraire sur des connaissances a priori. Dans le cadre de la reconnaissance audio, aucune représentation de caractéristiques conventionnelle n’a montré sa capacité à s’attaquer indifféremment à des problèmes de reconnaissance d’environnement ou de musique : diverses caractéristiques ont été introduites pour résoudre chaque tâche spécifiquement. Nous proposons ici un cadre général qui effectue la classification des signaux audio grâce à un problème d’apprentissage de dictionnaire supervisé visant à minimiser et maximiser les variations intra-classe et inter-classe respectivementNowadays, there are a lot of applications related to machine vision and hearing which tried to reproduce human capabilities on machines. These problems are mainly amenable to a temporal signals classification problem, due our interest to this subject. In fact, we were interested to two distinct problems, humain gait recognition and audio signal recognition including both environmental and music ones. In the former, we have proposed a novel method to automatically learn and select the dynamic human body-parts to tackle the problem intra-class variations contrary to state-of-art methods which relied on predefined knowledge. To achieve it a group fused lasso algorithm is applied to segment the human body into parts with coherent motion value across the subjects. In the latter, while no conventional feature representation showed its ability to tackle both environmental and music problems, we propose to model audio classification as a supervised dictionary learning problem. This is done by learning a dictionary per class and encouraging the dissimilarity between the dictionaries by penalizing their pair- wise similarities. In addition the coefficients of a signal representation over these dictionaries is sought as sparse as possible. The experimental evaluations provide performing and encouraging results
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Arnold, Morgan Jay. "Signals and noise." Thesis, Queensland University of Technology, 1996. https://eprints.qut.edu.au/105542/1/T%28BE%26E%29%201028%20Signals%20and%20noise.pdf.
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The broad-based goal of this thesis is to understand, detect, identify and quantify the abstract entity "signal in noise". In general this will be guided by the motivation to extract some form of underlying information, or signal,
from what we observe. Specifically this will involve signal and noise modelling, tackling some of the unresolved issues of signal processing including analysis of non-stationary and multicomponent signals non-Gaussian noise.
Some philosophical background is formulated which explains what ·we mean by the notions of signal and noise that ·we are using. This lays the foundation for some more specific investigations of signal models, noise models and analysis
techniques. Polynomial models for the phase of an analytic signal are first investigated and utilised to optimise some time- domain instantaneous frequency estimation techniques. These techniques, based on phase differencing,
significantly improve performance over traditional methods, such as the central finite difference. A new philosophy towards signal filtering, termed time-frequency peak filtering, is presented. This method is shown to enhance
signals in high noise environments, preserving frequency content far below normal noise thresholds. Good results are obtained for a broad range of non-stationary (general) signals. The effects of non-Gaussian noise are accounted
for by utilising higher-order cumulant information, specifically with a new methodology called higher-order probability distributions. Then we propose to model random variables using characteristic functions and derive
an estimation scheme for these quantities based on kernel functions. As a practical application this methodology is applied to the problem of testing for Gaussianity with results comparative to the best known of such tests.
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Lahr, Jacob [Verfasser], and Andreas [Akademischer Betreuer] Schulze-Bonhage. "Electromyographic signals in intracranial electroencephalographic recordings = Elektromyographische Signale in intrakraniellen EEG-Aufnahmen." Freiburg : Universität, 2012. http://d-nb.info/1123473927/34.
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Scoular, Spencer Charles. "Sampling and reconstruction of one-dimensional analogue signals." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283938.
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Millette, Veronique. "Signal processing of heart signals for the quantification of non-deterministic events." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28579.
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The issue of cavitation in mechanical heart valve (MHV) patients was first recognized when damaged mechanical heart valves were observed. Cavitation bubble implosion can cause mechanical damage to the valve structure and blood elements, when it occurs near the surface of the MHV. Some methods have been suggested to quantify the level of cavitation present in MHV patients. Two algorithms from the literature were selected for implementation and comparison. These algorithms were selected as they have been previously proposed and implemented for in vivo heart signals. In this thesis, a rigorous closed-form mathematical analysis of the algorithms is presented with the aim of improving robustness, reliability and accuracy. Improvements are made to the selected algorithms, including a new improved segmentation algorithm, alignment of the S1 and S2 peaks in the signal, and the implementation of the Short-Time Fourier Transform to study the time evolution of the energy in the signal. In vitro measurements were made using a left-heart simulator to test the new improved algorithm. The improvements result in better heart beat alignment and better detection and measurement of the random events in the heart signals, so that they may provide a method to analyze cavitation in MHV patients. The use of the Short-Time Fourier Transform allows the examination of the random events in both time and frequency allowing for further investigation and interpretation of the signal. Cavitation results from the physiologically realistic left-heart simulator indicate that cavitation may not occur under normal physiological heart conditions.
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Rasch, Jennifer [Verfasser]. "Signal Adaptive Methods To Optimize Prediction Signals in Video Coding / Jennifer Rasch." Berlin : epubli, 2019. http://d-nb.info/1199686522/34.
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Gartheeban, Ganeshapillai. "Methods to improve the signal quality of corrupted multi-parameter physiological signals." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/65969.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 121-125).
A modern Intensive Care Unit (ICU) has automated analysis systems that depend on continuous uninterrupted real-time monitoring of physiological signals such as Electrocardiogram (ECG), Arterial Blood Pressure (ABP), and the Photo Plethysmogram (PPG). Unfortunately, these signals are often corrupted by noise, artifacts, and missing data, which can result in a high incidence of false alarms. We present a novel approach to improve the Signal Quality of a multi-parameter physiological signal by identifying the corrupted regions in the signal, and reconstructing them using the information available in correlated signals. The method is specifically designed to preserve the clinically most signicant aspects of the signals. We use template matching to jointly segment the multi-parameter signal, morphological dissimilarity to estimate the quality of the signal segment, similarity search to nd the closest match from a database of templates, and time-warping to reconstruct the corrupted segment using the matching template. Experiments carried out on the MIT-BIH Arrhythmia Database, a multi-parameter ECG database with many clinically signicant arrhythmias, demonstrate the effectiveness of the method. Our method improved the classification accuracy of the beat type by more than 700% on the signal corrupted with white Gaussian noise, and increased the similarity to the original signal, as measured by the normalized residual distance, by more than 250%. When the method was applied to the multi-parameter physiological signal data from Cinc Challenge 2010 database at Physionet.org, our method improved the classification accuracy of beat type by more than 33 times on a signal corrupted with white Gaussian noise, and increased the similarity to the original signal by more than 280%.
by Gartheeban Ganeshapillai.
S.M.
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Yan, Yan. "Statistical signal processing for echo signals from ultrasound linear and nonlinear scatterers." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/11634.
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Malassenet, Francois Jacques. "Self-Affine signals and weighted multiresolution processes." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/14914.
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Walker, Michelle Elisabeth. "Mitochondrial protein targeting signals." Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/14627.
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Barnett, James B. "Camouflage of conspicuous signals." Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702486.
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Camouflage and aposematism are two seemingly contrasting and mutually exclusive forms of anti-predator defence. With natural variation in predator experience and motivation to attack, however, defended prey may benefit from incorporating aspects of camouflage in order to reduce their predator encounter rate. One potential mechanism is distance-dependent signals, which take advantage of limitations in visual acuity to produce highly salient signals that are functionally camouflaged when viewed from a distance. Aposematic patterns often contain high contrast elements which have been suggested to increase the saliency of the signal. At greater viewing distances, however, the perception of pattern will change as different components dominate perceptual grouping mechanisms and adjacent patches of colour are summed to create a combined colour. Using computational modelling of ecologically relevant visual predators, laboratory experiments with human observers, and field experiments with bird predation, this thesis investigates distance-dependent signals in artificial prey and in two highly salient aposematic species: the cinnabar moth caterpillar (Tyria jacobaeae Erebidae). and the dyeing poison frog (Dendrobates tinctorius Dendrobatidae). Where the combined colour of a striped aposematic pattern matches that of the background, pattern-blending can create effective camouflage to distant observers, and lead to significant survival benefits. On more complex, visually textured, backgrounds, however, the homogenous colour produced by pattern-blending may not recreate the background, and a target will be easily detected. Indeed, pattern-blending may prevent an aposematic signal from being identified at the distance at which it is first detected. In this situation, optimal aposematic signalling appears to be produced from a balance between signal distinctiveness and recognition. Field experiments and visual modelling suggest that for both T. jacobaeae and D. tinctorius combining aposematism with camouflage, by exploiting distance-dependent effects, can be advantageous. Observer distance and its exploitation by specific colour patterns are likely to be underappreciated components of defensive colouration.
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Routh, Joshua Keith, Jerris Methvin, Alstine Juan Van, Jeremy Radtke, and Bryan Richardson. "Biological Signals Interface Board." Thesis, The University of Arizona, 2009. http://hdl.handle.net/10150/192955.
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McCoy, Jan. "Signals to Muscle Growth." College of Agriculture, University of Arizona (Tucson, AZ), 1990. http://hdl.handle.net/10150/295660.
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Papenfuss, Frank. "Digital signal processing of nonuniform sampled signals contributions to algorithms & hardware architectures." Aachen Shaker, 2007. http://d-nb.info/987695959/04.
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Al-Lawzi, Mahmod Jasim Mohammed. "The development of adaptive signal processing algorithms for the recovery of periodic signals." Thesis, Cranfield University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484187.
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Ashraf, Pouya, Linnar Billman, and Adam Wendelin. "Teaching Signals to Students: a Tool for Visualizing Signal, Filter and DSP Concepts." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-297168.
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Students at Uppsala University have for some years been given the opportunity to take courses in subjects directly, or indirectly, related to the fields of signal processing and signal analysis. According to the directors of these courses, a considerable number of students are recurringly having difficulties grasping different concepts related to this field of study. This report covers a tool that easily allows teachers to visualize and listen to different manipulations of signals, which should help students get an intuitive understanding of the subject. Features of the system include multiple kinds of analog filters, sampling with variable settings and zero-order hold reconstruction. The finished system is flexible, tunable and modifiable to the teachers every need, making it usable for a wide variety of courses involving signal processing. The system meets its requirements even though individual components’ results de- viate slightly from ideal values.Studenter vid Uppsala Universitet har, under ett antal år, givits möjligheten att läsa kurser inom ämnen direkt, eller indirekt, relaterade till signalbehandling/signalanalys. Enligt kursansvariga för dessa kurser har en ansenlig andel av studenterna svårigheter med att förstå en del av de begrepp och fenomen som förekommer under kurserna. Denna rapport behandlar ett verktyg som ger lärare i dessa kurser möjlighet att på ett enkelt sätt visualisera och lyssna på olika manipulationer av signaler, vilket bör hjälpa studenterna bygga en intuition för ämnet. Systemets olika funktioner inkluderar flera olika typer av analoga filter, sampling med olika inställningar, och så kallad ’Zero-Order-Hold’ rekonstruktion. Det resulterande systemet är flexibelt, inställbart och modifierbart till användarens behov, vilket gör det applicerbart i flera kurser som innefattar signalbehandling/analys. Systemet möter kraven som ställs, även fast resultaten hos individuella komponenter avviker aningen från ideala värden.
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Shipilova, Ekaterina. "Separation of signals originating from simultaneous seismic sources by greedy signal decomposition methods." Electronic Thesis or Diss., CentraleSupélec, 2018. http://www.theses.fr/2018CSUP0005.
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L’acquisition de données sismiques avec des sources simultanées a récemment attiré beaucoup d’attention, tant dans l’industrie pétrolière et gazière que dans le monde académique, grâce à sa capacité à réduire le temps passé sur le terrain. Malgré le gain de temps évident, la méthode des sources simultanées a un inconvénient considérable: les sources interfèrent les unes avec les autres, créant des diaphonies dans les données, ce qui entraîne une augmentation significative de la complexité du traitement et des pertes potentielles de qualité. Un grand nombre des méthodes de séparation actuellement proposées nécessitent un prétraitement des données, par exemple, une suppression des ondes de surface. Dans cette thèse, nous proposons d'utiliser un modèle d'événement sismique piloté par les données dans une décomposition gloutonne pour obtenir une séparation adaptée aux données brutes sans aucun prétraitement. La méthode proposée consiste à identifier des caractéristiques cohérentes dans les données et à les classer en fonction de leur source d’origine. Nous utilisons deux applications imbriquées de Matching Pursuit Orthogonal, dont les dictionnaires sont constitués de modèles d'événements sismiques et d'ondelettes basés sur les données. Grâce à plusieurs étapes d'optimisation et en partant des conditions initiales appropriées, nous sommes en mesure de maximiser efficacement une fonction objectif non concave et d'obtenir une qualité de séparation satisfaisante, que nous démontrons sur des signaux des sources simultanées synthétiques et réelsSimultaneous-source seismic data acquisition has recently attracted great attention both in the oil and gas industry and in academia, thanks to its capacity to save data acquisition time. Despite the evident time-saving advantage, the simultaneous-source method has a considerable draw-back: the sources interfere with each other creating cross-talk in the data, which leads to significant increase of the processing complexity and potential loss in the subsurface image quality. Recent advances in processing and imaging allow acceptable handling of the cross-talk, however, specific processing methods adapted for blended data still need to be improved. Many of the currently proposed separation methods need some preprocessing of the data, e.g., surface waves suppression. In this thesis, we propose to use a data-driven seismic event model in a greedy decomposition to obtain a separation suitable for raw data without any preprocessing. The proposed method is based on identifying coherent features in the data and classifying them according to their source of origin. We use two nested applications of Orthogonal Matching Pursuit, whose dictionaries are constituted of data-driven models of seismic events and wavelets. Thanks to several optimization steps and starting with appropriate initial conditions, we are able to effectively maximize a non-concave objective function and achieve a satisfactory separation quality, which we demonstrate on synthetic and real simultaneous-source signals
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Seo, Jong-Soo. "Blind fault detection and source identification using higher order statistics for impacting systems." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326784.
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Peiffer, John P. "Fatigue testing of stiffened traffic signal structures." Laramie, Wyo. : University of Wyoming, 2009. http://proquest.umi.com/pqdweb?did=1888253611&sid=11&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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White, Rehema Mary. "Seasonality of reproduction : environmental signals and the role of the pineal in signal transduction /." Title page, summary and contents only, 1994. http://web4.library.adelaide.edu.au/theses/09PH/09phw58725.pdf.
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Charisis, Konstantinos. "Demodulation of OFDM Signals in the Presence of Deep Fading Channels and Signal Clipping." Thesis, Monterey, California. Naval Postgraduate School, 2012. http://hdl.handle.net/10945/7320.
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In this thesis, an optimal estimation algorithm, based on the Kalman Filter, is introduced for data recovery of orthogonal frequency-division multiplexed (OFDM) signals transmitted over fading channels. We show that the use of a zero prefix (ZP) along with a fast Fourier transform (FFT) operation zero padded to twice the data length allows for the recovery of subcarriers located next to a deep faded (at low signal-to-noise ratio [SNR]) values, exploiting all other subcarriers with higher SNR. The same approach is also shown to improve demodulation in the presence of signal clipping due to high peak to average power ratio (PAPR), as is often seen in OFDM signals. The proposed method assumes prior knowledge of the channel, usually estimated using the preamble. Testing was conducted for random channels with zero frequency response at a random frequency 0 and a signal in additive white Gaussian noise for various conditions. Further testing was done with typical Stanford University Interim (SUI) channels. Additionally, the use of the method to recover OFDM signals based on the IEEE 802.11 and 802.16 standards was examined. Results show that the proposed optimal estimation algorithm has very satisfactory performance compared to the standard OFDM receiver algorithm.