Dissertations / Theses on the topic 'Frequency jump'
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Tsai, Ping-Chen. "An empirical study on jumps in asset prices using high-frequency data : volatility specification, jumps detection & the modelling of jump intensity." Thesis, Lancaster University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.663227.
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To provide further evidences on jumps in asset prices, in this thesis we conduct an empirical analysis on high-frequency data from a stock index and consider the problem of identifying jumps at intraday intervals. Our approach generalizes two existing methods in the literature in terms of estimating spot volatility and of correcting for the spurious rejection problem due to multiple testing. The proposed procedure directly depends on a credible volatility model that we specify and calibrate from the index data. By simulating the volatility model, it is shown that a relevant parameter which governs the shape of the generalized extreme value (GEV) distribution determines the critical regions of jump tests. Empirical sizes of jump tests can then be held at nominal level approximately when the testing procedure is applied to high-frequency returns. We also study the dynamics of detected jumps and model their time-varying intensities with a linear self-exciting point process.
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Sanderson, Mark Findlay. "Whole body vibration : stimulus characteristics and acute neuromuscular responses." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/15741.
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Whole body vibration (WBV) delivers a stimulus to the body via an oscillating platform and remains a relatively new area of research. Several applications of WBV stimuli have been developed as strength training and rehabilitation modalities, but inconsistent results have been published. There is little knowledge underpinning the mechanisms to explain the elicited neuromuscular responses to WBV and a wide range of WBV parameters across the literature. As a result, safe and effective protocols are yet to be established or validated. The aim of this current research was to investigate: the electromyography (EMG) and explosive performance responses to varying WBV frequencies; the effect of WBV data analysis techniques; and the influence of external factors on WBV stimulus and neuromuscular responses. Three main studies were completed: 1. An individualised response of both EMG and jump performance appears to exist dependent on vertical WBV frequency, in trained participants. This is in spite of no overall frequency dependent effect of EMG or performance responses across participants as a group. The influence of the role of expectancy effect appears minimal following this particular WBV protocol. 2. There was a significant effect of filter technique on EMG data recorded during vertical WBV. A tailored, WBV specific notch filter technique may offer an effective balance; excluding WBV noise artifacts without removing significant portions of valuable muscle signal EMG data. 3. The influence of external load on WBV acceleration output also appears minimal. Platform acceleration output was dependent on WBV frequency, as expected. Lower accelerations were recorded in superior body segments, suggesting a dampening mechanism, which was also proportionally dependent on frequency. EMG activity of upper and lower leg segments may differ in response to frequency, likely due to transmission distances involved. This may partially account for a potential dampening mechanism. In addition, a protocol to quantify WBV stimuli delivered by this particular WBV type illustrated significant differences in theoretical and actual parameters. This may explain not only the lack of overall explosive performance effect reported earlier; but also the inconsistent WBV literature. Future research should quantify WBV stimulus before investigating possible neuromuscular responses to individualised protocols, which may be assessed via EMG activity.
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Rohani-Mehdiabadi, Bijan. "Frequency discriminator detection in frequency-selective fading environments." Curtin University of Technology, School of Electrical and Computer Engineering, 1998. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=12148.
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In recent years, millions of customers all over the world have been subscribing to mobile telephony services which are based on modern digital transmission. At the high transmission bit rates that these systems use, the mobile radio channel exhibits frequency-selective fading characteristics. Under such conditions, the received signal could experience significant intersymbol interference (ISI) from severe distortion to the waveform of the received baseband signal. Therefore, such techniques as adaptive waveform equalisation or adaptive maximum likelihood sequence estimation (MLSE) are used in modern digital mobile radio telephone systems to combat this undesirable ISI. These adaptive schemes have almost always been used in conjunction with coherent demodulation in the receivers.This study examines the application of noncoherent demodulation, in the form of frequency discriminator detection, as an alternative to coherent demodulation. The GSM (Global System for Mobile Communications) standard has been used as the basis for this investigation. It has been shown analytically that in the presence of frequency-selective fading, a propagation environment common to the GSM system, the use of frequency discriminator detection gives rise to nonlinear ISI in the demodulated signal. It has also been shown that frequency-selective fading could cause large unwanted "spikes" to appear in the demodulated signal, thus leading to a severe degradation in the bit-error-rate (BER) performance. Consequently, several waveform distortion cancellation schemes for combatting the nonlinear ISI have been formulated. The BER performances of these proposed schemes, under various propagation conditions, have been studied by computer simulation.Furthermore, it has been observed that the undesirable "spikes", that occur in the demodulated signal due to frequency-selective fading, could be ++suppressed by the use of inverse-limiting in conjunction with frequency discriminator detection. As a result, an effective adaptive detection scheme has been formulated, based on modelling the combination of the GMSK modulator, the mobile channel, the frequency discriminator, and any transmit and receive fitters, as a finite-state machine. The transmitted data is then detected using an MLSE. The BER performance of this proposed adaptive detection scheme has been extensively investigated by computer simulation. This has been carried out assuming various propagation conditions, including the two-ray fading channel model with equal path powers and relative delays of up to four bit periods, the maximum relative delay considered in the GSM system. Also, the effectiveness of the proposed adaptive detection scheme in combatting IS] has been investigated by computer simulation based on the six-ray GSM empirical propagation models for typical urban (TU), hilly terrain (HT) and rural area (RA) environments. The computer simulated results confirm that the voice grade performance required for the GSM system could be achieved by the proposed adaptive detection scheme in all the recommended GSM propagation models considered. Furthermore, the BER performance of the receiver remains unaffected by a carrier frequency offset of up to 2 kHz.
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Wong, Kar Lun (Clarence). "Space-time-frequency channel estimation for multiple-antenna orthogonal frequency division multiplexing systems." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100244.
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We propose a linear mean square error channel estimator that exploits the joint space-time-frequency (STF) correlations of the wireless fading channel for applications in multiple-antenna orthogonal frequency division multiplexing systems. Our work generalizes existing channel estimators to the full dimensions including transmit spatial, receive spatial, time, and frequency. This allows versatile applications of our STF channel estimator to any fading environment, ranging from spatially-uncorrelated slow-varying frequency-flat channels to spatially-correlated fast-varying frequency-selective channels.The proposed STF channel estimator reduces to a time-frequency (TF) channel estimator when no spatial correlations exist. In another perspective, the lower-dimension TF channel estimator can be viewed as an STF channel estimator with spatial correlation mismatch for space-time-frequency selective channels.
Computer simulations were performed to study the mean-square-error (MSE) behavior with different pilot parameters. We then evaluate the suitability of our STF channel estimator on a space-frequency block coded OFDM system. Bit error rate (BER) performance degradation, with respect to perfect coherent detection, is limited to less than 2 dB at a BER of 10-5 in the modified 3GPP fast-fading suburban macro environment. Modifications to the 3GPP channel involves reducing the base station angle spread to imitate a high transmit spatial correlation scenario to emphasize the benefit of exploiting spatial correlation in our STF channel estimator.
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Hill, Martin T. "New techniques for measurement and tracking of phase and frequency." Curtin University of Technology, Australian Telecommunications Research Institute, 1997. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=10983.
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This thesis presents and analyses new techniques to measure and track the phase and frequency of high frequency narrow bandwidth signals. In particular, these techniques are all digital in nature or can be implemented in digital integrated circuit technology.Presented first is a frequency measurement technique which involves sampling at regular intervals a binary quantized narrow band signal. The binary quantized samples are digitally processed to obtain the instantaneous frequency of the signal.It is shown that small phase movements in the signal can be detected even though the sampling occurs at a rate much lower than the signal frequency; that there are no frequency offsets in the frequency measurement technique; that the phase error in the technique is small and bounded provided the signal frequency is maintained within derived limits. Other properties of the technique are also derived.The frequency measurement technique is experimentally demonstrated in a number of typical applications.Secondly, a new phase tracking system is presented, which has similarities to conventional phase locked loops. However, unlike phase locked loops, the new system incorporates a local reference source which effectively stabilizes the phase estimate of the signal input being tracked.It is shown that the new system has the following advantages: Precise centre frequency, controllable lock range, and elimination or reduction of the effects of imperfections like voltage controlled oscillator phase noise. General behaviour in noise of the new phase tracking system is derived.An implementation of the new system is presented which employs the frequency measurement technique described above. This implementation is characterized by very precise centre frequency, high phase noise suppression, and can be built almost entirely in digital integrated circuit technology. The new system is ++experimentally demonstrated in some typical applications.The techniques presented in this thesis provide improvements of several orders of magnitude in the ability of systems implemented in digital integrated circuit technology to: Measure and control phase and frequency of narrow band signals; Implement high performance phase tracking systems.
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Chopp, Philip. "Frequency-translating delta-sigma modulation for bandpass analog-to-digital conversion of high- frequency signals." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110454.
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A traditional heterodyne receiver downconverts its input signal to one or more intermediate frequencies (IFs) before digitizing it at baseband. In a digital-IF receiver, the input signal is digitized directly at an IF using a bandpass analog-to-digital converter (ADC). Accordingly, the digital-IF receiver replaces the image-reject mixers and baseband filters of a heterodyne receiver with accurate and effcient digital functions, and therefore provides greater potential for reconfigurability. In order to maximize the advantages of a digital-IF receiver, a common design objective is to position the bandpass ADC as close as possible to the antenna, and to operate on the input signal at a high IF.A bandpass ADC is effciently implemented using a delta-sigma modulator, which can provide high-resolution A/D (analog-to-digital) conversion over a relatively narrow band around an IF. In order to operate on high-IF signals, conventional bandpass delta-sigma modulators require high-frequency filters and high sampling rates, which can result in high sensitivity to circuit non-idealities and high power consumption. These disadvantages are addressed by the frequency-translating delta-sigma modulator, which uses downconversion mixing inside its delta-sigma loop to process high-IF signals using low sampling rates and primarily low-frequency filters.This thesis investigates frequency-translating delta-sigma modulators for direct A/D conversion of high-IF signals. It first analyses the system architecture and performance limitations of an existing type of frequency-translating delta-sigma modulator that is based on image-reject mixing. This analysis is supported by an initial study on the effect of timing errors in a conventional delta-sigma modulator. The thesis then introduces a novel frequency-translating delta-sigma modulator that is based on single-path mixing. The advantages of the presented single-path architecture are demonstrated using an experimental delta-sigma modulator.The experimental delta-sigma modulator is designed to digitize a 4 MHz input-signal band that is centred at an IF of 225 MHz. It uses a local oscillation signal with a frequency of 200 MHz to downconvert this input-signal band to an IF of 25 MHz inside its delta-sigma loop, and samples at 100 MHz. The experimental prototype was fabricated in a standard 65 nm CMOS process. It achieves a peak SNDR of 55 dB and a dynamic range of 57.5 dB, while consuming 13 mW from a 1-V power supply. It has a full-scale range of 700 mVp-p.Un recepteur heterodyne traditionnel transpose un signal en entree vers une ou plusieurs frequences intermediaires (FI) avant de le numeriser a la bande de base. Dans un recepteur numerique FI, le signal en entree est numerise directement a la frequence FI a l'aide d'un convertisseur analogique-numerique passe-bande. Par consequent, le recepteur numerique FI remplace les melangeurs de rejection d'image et les filtres a bande de base d'un recepteur heterodyne traditionnel par des fonctions numeriques precises et efficaces. De ce fait, le recepteur numerique FI offre plus de possibilites de reconfiguration. Afin de maximiser les avantages d'un recepteur numerique FI, un objectif de conception frequent consiste a placer le convertisseur analogique-numerique passe-bande aussi pres que possible de l'antenne et de numeriser le signal en entree a une frequence FI elevee.Un convertisseur analogique-numerique passe-bande peut etre realise efficacement en utilisant un modulateur delta-sigma. En effet, ce dernier procure une conversion A/N (analogique-numerique) a haute resolution sur une bande relativement restreinte centree autour d'une frequence FI. Afin de fonctionner sur des signaux a frequences FI elevees, les modulateurs delta-sigma passe-bande classiques requierent des filtres hautes-frequences et des frequences d'echantillonnage elevees, ce qui peut les rendre tres sensibles aux non-idealites du circuit et mener a une consommation electrique importante. Il est possible de remedier a ces inconvenients en utilisant un modulateur delta-sigma a transposition de frequence. En effet, ce dernier utilise des melangeurs dans sa boucle delta-sigma pour traiter des signaux a frequence FI elevee a des frequences d'echantillonnage faibles avec principalement des filtres basses-frequences.Cette these etudie l'utilisation de modulateurs delta-sigma a transposition de frequence pour une conversion A/N directe de signaux a frequence FI elevee. Elle analyse d'abord l'architecture et les limitations de performance d'un modulateur delta-sigma a transposition de frequence base sur un melangeur de rejection d'image. Cette analyse est appuyee par une etude initiale effectuee sur l'effet d'erreurs d'horloge sur un modulateur delta-sigma classique. Cette these introduit ensuite un nouveau modulateur delta-sigma a transposition de frequence base sur un melangeur de mono-trajet. Les avantages de cette architecture sont demontres a l'aide d'un prototype de modulateur delta-sigma.Le prototype de modulateur delta-sigma est concu afin de numeriser une bande de signaux en entree de 4 MHz centree autour d'une FI de 225 MHz. Il utilise un signal a oscillation locale d'une frequence de 200 MHz pour transposer cette bande de signaux en entree vers 25 MHz a l'interieur de sa boucle delta-sigma et effectue l'echantillonnage a 100 MHz. Ce prototype a ete realise en utilisant un procede CMOS standard de 65 nm. Il a un SNDR de 55 dB et une gamme dynamique de 57.5 dB tout en consommant 13 mW pour une alimentation de 1-V. Sa plage d'amplitude maximale est de 700 mVp-p.
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McRae, Ken 1962. "The locus of word frequency effects /." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=64083.
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HUANG, WEI. "Improved PPP for time and frequency transfer and real-time detection of GNSS satellite clock frequency anomalies." Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2842527.
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Monfet, Frederic. "Turbo equalization using frequency-domain shortening filter." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99527.
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Turbo equalization provides excellent performance but the complexity associated with this technique prohibits its use in application with severe inter-symbol interference (ISI) channel; the turbo equalizer complexity increases exponentially with the length of the channel impulse response (CIR) and the modulation level used for data transmission. In this work, a combined frequency-domain pre-equalizer with a turbo equalizer is proposed in an attempt to reduce the length of the CIR used by the turbo equalizer and hence the complexity of the receiver. The optimum selection of coefficients of the frequency-domain pre-equalizer and desired channel impulse response is discussed. With the proposed receiver, the complexity of the turbo equalizer can be controlled by pre-selecting the length of the desired channel impulse response. This complexity reduction is achieved at the cost of an increase in the noise level, which degrades the performance. The effect on the performance of such pre-equalizer is studied analytically. The overall performance of the proposed receiver for different length of the desired channel impulse response is studied via analytical comparison and simulation. Simulation results on performance in various frequency-selective fading channels indicate a substantial performance gain when compared to a conventional feed-forward equalizer (FFE) plus decision-feedback equalizer (DFE) receiver. Finally, in cases where a large alphabet is used for modulation, the reduced-search BCJR (Bahl, Cocke, Jelinek, and Raviv) [1] algorithm is utilized in the proposed receiver to further reduce the complexity of the receiver.
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Aboussouan, Patrick. "Frequency response estimation of manipulator dynamic parameters." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65927.
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Chen, Xi. "Sequential Monte Carlo radio-frequency tomographic tracking." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104844.
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Target tracking in over a small-scale area using wireless sensor networks (WSNs) is a technique that can be used in applications ranging from emergency rescue after an earthquake to security protection in a building. Many target tracking systems rely on the presence of an electric device which must be carried by the target in order to reports back its location and status. This makes these systems unsuitable for many emergency applications; in such applications device-free tracking systems that where no devices are attached to the targets are needed. Radio-Frequency (RF) tomographic tracking is one such device-free tracking technique. This system tracks moving targets by analyzing changes in attenuation in wireless transmissions. The target can be tracked within the sensor network area without being required to carry an electric device.Some previously-proposed device-free tracking approaches require a time-consuming training phase before tracking can be carried out, which is time-consuming. Others perform tracking by sacrificing part of the estimation accuracy. In this thesis, we propose a novel sequential Monte Carlo (SMC) algorithm for RF tomographic tracking. It can track a single target moving in a wireless sensor network without the system needing to be trained. The algorithm adopts a particle filtering method to estimate the target position and incorporates on-line Expectation Maximization (EM) to estimate model parameters. Based on experimental measurements, the work also introduces a novel measurement model for the attenuation caused by a target with the goal of improving estimation accuracy. The performance of the algorithm is assessed through numerical simulations and field experiments carried out with a wireless sensor network testbed. Both simulated and experimental results demonstrate that our work outperforms previous RF tomographic tracking approaches for single target tracking.Suivi de cible dans la zone à petite échelle en utilisant les réseaux de capteurs sans fil est une technique qui peut être largement utilisé dans des applications telles que le sauvetage d'urgence après un tremblement de terre, ou la protection de la sécurité dans un bâtiment. Beaucoup de systèmes de poursuite de cibles nécessitent un dispositif électrique réalisée par l'objectif de faire rapport de ses localisation instantanée et le statut. L'inconvénient rend ces systèmes ne conviennent pas pour des applications nombreuses interventions d'urgence, dispositif sans systèmes de suivi qui ne les périphériques connectés sur les objectifs sont nécessaires. Radio-Fréquence (RF) suivi tomographique est l'une des techniques dispositif de suivi-libres. Il s'agit d'un processus de suivi des cibles mobiles en analysant l'évolution de l'atténuation dans les transmissions sans fil. La cible peut être suivi dans la zone de réseau de capteurs, tandis que les appareils électriques ne doivent être effectués. Cependant, certaines approches précédentes dispositif de suivi-libre nécessite une phase d'entraînement avant de suivi, ce qui prend beaucoup de temps. Autres effectuer un suivi par scarification partie de précision de l'estimation.Dans cette thèse, nous proposons une nouvelle Monte Carlo séquentielles (SMC) algorithme de suivi RF tomographique. Il peut suivre une cible unique sans formation du système dans un réseau de capteurs sans fil. L'algorithme de filtrage particulaire adopte la méthode pour estimer la position cible et intègre en ligne Expectation Maximization (EM) pour estimer les paramètres du modèle. Sur la base de mesures expérimentales, le travail introduit également un modèle de mesure de roman pour l'atténuation provoquée par une cible pour améliorer la précision d'estimation. La performance de l'algorithme est évaluée par des simulations numériques et expériences sur le terrain avec un réseau de capteurs sans fil banc d'essai. Les deux résultats simulés et expérimentaux démontrent que notre travail surpasse précédente approche RF suivi tomographique pour le suivi de cible unique.
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Sendashonga, Mireille. "Image quality assessment using frequency domain transforms." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99537.
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Measurement of image quality plays a central role in optimization and evaluation of imaging systems. The most straight-forward way to assess image quality is subjective evaluations by human observers, where the mean value of their scores is used as the quality measure. However, objective (quantitative) measures are needed because subjective evaluations are impractical and expensive. The aim of this thesis is to develop simple and low-complexity metrics for quality assessment of digital images.Traditionally, the most widely used quantitative measures are the mean squared error and measures that model the human visual system. The proposed method uses the Discrete Cosine Transform and the Discrete Wavelet Transform to divide images into four frequency bands and relates the visual quality of the distorted images to the weighted average of the mean squared error between original and distorted images within each band.
The performance of the metrics presented in this thesis is tested and validated on a large database of subjective quality ratings. Simulations show that the proposed metrics accurately predict visual quality and outperform current state-of-the-art methods with simple and easily implemented processing steps.
Extensions of the proposed image quality metrics are investigated. More particularly, this thesis explores image quality assessment when the reference image is only partially available (reduced reference settings), and presents a method for successfully quantifying the quality of distorted images in such settings.
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Massicotte, Mathieu. "Graphene electronics for high frequency, scalable applications." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110547.
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The advent of large-scale graphene grown by chemical vapor deposition (CVD) offers a viable route towards high-frequency (HF) graphene-based analogue electronics. A significant challenge, however, is to synthesize and fabricate HF graphene-based devices with high carrier mobility. Here, we report our efforts to understand and control the CVD growth mechanism of graphene on copper, to characterize the synthesized film, and to fabricate graphene transistors and HF devices. In parallel, we describe the synthesis of large pristine dendritic graphene flakes that we name graphlocons. The electronic transport properties and magnetoresistance were assessed from 300 K to 100 mK and mobility up to 460 cm^2/Vs was obtained with a residual charge carrier density of 1.6x10^12 cm^-2. HF scattering parameters were measured from 0.04 to 20 GHz but they showed no dependence on temperature and magnetic field. This work provides a starting point for improving the structural and electronic properties of CVD graphene, and for exploring new phenomena in the GHz frequency range.L'avènement du graphène produit à grande-échelle par dépôt chimique en phase vapeur (CVD) ouvre une voie vers l'électronique haute-fréquence (HF) à base de graphène. Synthétiser du graphène possédant une grande mobilité des porteurs de charge et l'incorporer à des dispositifs HF constitue cependant un important défi. Nous présentons ici le fruit de nos efforts pour comprendre et contrôler le mécanisme de croissance CVD du graphène sur le cuivre, caractériser les films ainsi produits, et fabriquer des transistors et dispositifs HF à base de graphène. Parallèlement, nous décrivons la synthèse de grands flocons dendritiques de graphène que nous appelons graphlocons. Les propriété électroniques et la magnetorésistance de ces échantillons ont été mesurées de 300 K à 100 mK et la mobilité la plus élevée obtenue est de 460 cm^2/Vs avec une densité de porteurs de charge résiduels de 1.6x10^12 cm^-2 . Les paramètres S de haute fréquence ont été mesurés de 0.04 à 20 GHz mais aucune dépendance en température ou champ magnétique n'a été observée. Ce travail fourni un point de départ pour améliorer les propriétés structurales et électroniques du graphène produit par CVD, et pour explorer de nouveaux phénomènes dans le domaine des GHz. .
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Ellis, Lee David. "Potassium channel control of neuronal frequency response." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103381.
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The processing of sensory signals is an important, yet complex task in which a system must extract behaviorally relevant stimulus patterns from a vast array of sensory cues. When a neuron within a major sensory area is presented with a stimulus, one of the important characteristics used to distinguish between types of input is frequency. Often sensory neurons are tuned to narrow stimulus frequency ranges and are thus charged with the processing of subtypes of sensory signals. The weakly electric fish Apteronotus lepthorhynchus senses it's environment through modulations of a self-generated electric field. Two main types of sensory signals can be distinguished based on their frequency patterns. Prey stimuli cause low frequency perturbations of the electric field, while communication signals often result in high frequency signals. Pyramidal neurons in the electrosensory lateral line lobe (ELL) encode the low frequency signals with bursts, while the high frequency signals are relayed with single spikes. This thesis describes how a pyramidal neuron's response patterns can be tuned to specific frequencies by the expression of distinct classes of potassium channels.I have cloned 3 small conductance (SK) calcium activated potassium channels from cDNA libraries created from the brain of Apteronotus. I have subsequently localized the AptSK channels throughout the brain using both in situ hybridization (AptSK1, 2 & 3) and immunohistochemical (AptSK1 & 2) techniques. The 3 channels showed distinct expression patterns, with the AptSK1 & 2 channels showing a partially overlapping expression pattern, while AptSK3 appears to be expressed in unique areas of the brain. In the ELL AptSK1 & 2 show a partially overlapping expression pattern, appearing in similar pyramidal neurons. However, their distribution within individual cell is unique, with AptSK1 showing a dendritic localization, while AptSK2 is primarily somatic. We have demonstrated that the unique expression pattern of the somatic AptSK2 channel in the ELL coincides with the functional SK currents evaluated through in vitro electrophysiology. Further we have shown that neurons that encode low frequencies do not possess functional SK channels. It thus appears that the presence of the AptSK2 channel subtype can predispose a neuron to respond to specific types of sensory signals.
In an attempt to evaluate if second messengers could modify the AptSK control of frequency tuning I investigated the consequences of muscarinic acetylcholine receptor (mAChR) activation on a pyramidal neurons response patterns. While it had been shown in vivo that mAChR activation increased a pyramidal neuron's response to low frequencies, I have found that this was not due to a decrease in AptSK current, but rather appears to be the result of a down-regulation of an A-type potassium channel.
Taken together the studies that comprise this thesis show how the selective expression of a single potassium channel subtype can control a sensory neurons response to specific environmental cues. The secondary modulation of the A-type current highlights the potential for a second messenger to control a neuron's sensory response through the down-regulation of constitutively expressed potassium current.
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Mai, Hilmar [Verfasser], Uwe [Akademischer Betreuer] Küchler, Markus [Akademischer Betreuer] Reiß, and Michael [Akademischer Betreuer] Sørensen. "Drift estimation for jump diffusions : time-continuous and high-frequency observations / Hilmar Mai. Gutachter: Uwe Küchler ; Markus Reiß ; Michael Sørensen." Berlin : Humboldt Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät II, 2012. http://d-nb.info/102691423X/34.
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Isbring, Evelina. "A longitudinal study of the frequency of knee pain and the effect on countermovement jump at a sports secondary school." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-33937.
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Background: Studies have shown that participation in sports during adolescence has several positive aspects, both physical and mentally. Today there is more focus on competition than before and more adolescents choose to specialize in one sport. High sport specialization can cause a higher risk of injuries. Knees are one of the most common sites for adolescence to experience pain in and girls are more often exposed to this problem, compared to boys. Aim: The aim of the study was to longitudinally investigate the frequency of reported knee pain in 7th grade and 9th grade in a secondary school with a sports profile stratified for sex, difference in frequency of knee pain between 7th and 9th grade and whether knee pain affected performance in countermovement jump with arm swing. Methods: To compare frequency of knee pain between 7th and 9th grade, the test subjects (n=42, 17 girls and 25 boys) that answered the questionnaire about knee pain both years were included. The questionnaire had six options for frequency, where those who reported “never” or “rarely” were grouped as “no knee pain”. Those who reported “monthly”, “weekly”, “more than once a week” or “almost daily” were grouped as “knee pain”. Jump height was measured by countermovement jump with arm swing. The tests were performed twice, in May 2014 when the test subjects were in 7th grade (age: mean (SD) 14±0.2) and in May 2016 in 9th grade (age: 16±0.2). Results: In 7th grade, 74% reported knee pain (girls 82 %, boys 68%). In 9th grade, 36% reported knee pain (girls 36%, boys 35%). The difference between the frequency of knee pain in 7th and 9th grade was significant, with a lower frequency in 9th grade. In 7th grade the jump height for those with knee pain was 32.9±7.5 cm, and for those with no knee pain 33.8±5.6 cm. In 9th grade the jump height for those with knee pain was 33.5±7.2 cm, and for those with no knee pain 36.5±10.1 cm. Conclusion: The frequency of knee pain decreased significant from 7th to 9th grade. There was no significant difference regarding jump height in countermovement jump with arm swing between the group that reported monthly to almost daily knee pain, and the group that reported that they experienced knee pain rarely or never. The result of this study therefore indicates that self-reported knee pain does not affect jumping performance.
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Kim, Hyung-Seuk 1976. "Low voltage CMOS frequency synthesizers for RF applications." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82607.
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Frequency synthesizers play an important role in modern communications and timing systems. The output of frequency synthesizers may be used as the local oscillator signal in superheterodyne transceivers, or in frequency modulation/demodulation. Fully integrated CMOS RF synthesizers are currently a major research topic. Several publications demonstrated improvements in a variety of aspects such as phase noise, power consumption, and tuning range. However, very low voltage frequency synthesizers are very challenging, since they usually have a limited tuning range and a relatively high phase noise. This research work demonstrates a new architecture to achieve a wide tuning range and low phase noise from a very low voltage supply. The synthesizer is fully integrated in a 0.18 mum CMOS technology covering the 5 GHz WLAN frequency range, requiring only a 1-V power supply. The second part of this thesis consists of the implementation of a 2.4-GHz fractional-N frequency synthesizer to be compatible with two MEMS resonators that resonate at 20-MHz and 70-MHz.
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Zhang, Xuan 1968. "Analysis-synthesis and time-frequency scaling of phonocardiogram." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23762.
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The analysis-synthesis of eleven phonocardiograms (PCGs) representing the normal and pathological conditions of the heart was performed by the damped sinusoidal method and the matching pursuit method. The normalized root-mean-square error (NRMSE) was used for the quantitative comparison of the temporal and the time-frequency representations of the original and the reconstructed signals. The matching pursuit method was found to be more suitable to the properties of both the transient heart sounds and the noise-like heart murmurs of the PCGs, therefore providing better analysis-synthesis results than the damped sinusoid model. It was applied to the transformations of the PCG signals, including time-scale expansion, frequency-scale expansion, and joint time-frequency expansion. A scaling/inverse-scaling process was set up for quantitative evaluation of the scaling performance. The spectrogram was used to calculate the NRMSE for the quantitative comparison of the PCG energy in the time-frequency domain, and both the spectrogram and the Wigner distribution were used for visual comparison. The results showed that the matching pursuit method is an effective technique for the time-frequency scaling transformations of PCGs, although its effectiveness is strongly related to the optimization of the parameters for the decomposition of the signals.
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Kannan, Shrikalaa. "Radio frequency heating of shell eggs-a prelude." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106620.
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Owing to their rich nutritive value, eggs serve as potential hosts to pathogenic microbes like Salmonella enteritidis. Administering heat treatments is the best solution for controlling these pathogens. However, heating affects the quality of the egg due to denaturation of proteins. Therefore a technique which causes minimal changes to the functional properties of the egg protein needs consideration.In this study, the suitability of Radio frequency (RF) treatments of eggs is evaluated for effectiveness in terms of reducing/eliminating the microbial load. Finite difference time domains (FDTD) and Finite element models (FEM) were developed based on preliminary laboratory trials to simulate the electric field and temperature distribution in the egg components keeping in mind the dielectric properties, shape and composition of in-shell eggs.Laboratory scale experiments were conducted to determine the dielectric properties of individual egg components followed by an investigation of the heating rates of individual egg components as well as intact in-shell eggs at different electric field strengths, where the electrode voltages are 2.5 kV, 3.5 kV and 4.25 kV with 60 mm spacing between the electrodes. The heating trends were then analyzed to obtain the time required to attain the targeted temperature. Models for calculating the dielectric parameters were presented.As heat treatments invariably affect the functional properties of eggs the heat induced changes with respect to properties like foam stability, foam density, viscosity and turbidity were studied and compared with the physical properties of raw eggs. RF treated eggs showed minimal changes at lower power levels. However the change in properties was more pronounced at higher power levels. The coagulation taking place within the eggs at higher power levels with a view to assessing the quality of heat treated eggs was studied by means of hyperspectral imaging (400-1700 nm).The heat treatment process was validated by inoculating egg with a microbial contaminant and treating them in an RF applicator. The results indicated that RF heating may possibly serve as a way to pasteurize the eggs provided the process is improved and optimized to reach the required pasteurization temperature with minimum damage to the functional properties of the egg.En raison de leur riche valeur nutritive, les œufs frais peuvent potentiellement être contaminés par des microorganismes pathogènes comme la Salmonella enteritidis. Il est possible de contrôler les pathogènes alimentaires par l'utilisation judicieuses de traitements thermiques. Cependant, les traitements thermiques conventionnels causent la dénaturation totale ou partielle des protéines présentent dans le blanc et le jaune d'oeuf. Par conséquent, une technique qui permettrait de contrôler la contamination dans les œufs frais tout en maintenant les propriétés fonctionnelles des protéines de l'œuf doit être examinée.Dans cette étude, l'adéquation de l'énergie des fréquences radios (RF) à 27 MHz pour le traitement thermique des œufs frais a été est évaluée. Des modèles en différences finies à dimension temporelle (FDTD) et des modèles d'éléments finis (FEM) ont été développés et utilisés pour simuler le champ électrique et pour prédire la distribution de la température dans les œufs frais en coquille et cela, en tenant compte des propriétés diélectriques, de la géométrie et la composition.Les propriétés diélectriques des composants de l'œuf ont été mesurées en tenant compte de leur dépendance à la température. Par la suite, des essais en laboratoire ont été effectués pour déterminer les taux de chauffage des composants exposés à des niveaux de puissance de 2,5 3,5 et 4,25 kV. Les tendances de chauffage diélectrique ont été analysées et les temps requis pour atteindre la température cible ont été déterminés. Les modèles de prédiction des paramètres diélectriques ont aussi été développés.Les effets des traitements thermiques sur les propriétés fonctionnelles des composants des oeufs ont été étudiés. Les paramètres retenus étaient : la stabilité et la densité de la mousse, la viscosité et la turbidité des blancs d'œufs. Les résultats on indiqués que propriétés fonctionnelles des œufs traités aux niveaux de puissance de 2,5 et 3,5 kV étaient presque identiques à celles des œufs frais non-traités. Cependant, les changements observés étaient plus prononcés 4,25 kV. L'imagerie hyperspectrale (400 à 1 700 nm) a été utilisée pour déceler la coagulation du blanc d'œuf après le traitement thermique des œufs en coquille.Le processus de traitement thermique a été validé par l'inoculation d'œufs frais avec une souche non-pathogénique de E. Coli. Par la suite, les œufs inoculés ont été traités thermiquement à l'aide du chauffage RF. Les résultats ont indiqué que le chauffage RF à 27 MHz était une méthode qui offrait un bon potentiel pour pasteuriser les œufs frais en coquille. D'autres études seront nécessaires pour optimiser la distribution de l'énergie RF et minimiser ses effets sur les propriétés fonctionnelles du blanc d'œuf.
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Potvin-Trottier, Laurent. "Temporal frequency image correlation techniques: development and characterization." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110729.
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Protein transport and trafficking are essential processes in living cells and therefore, important to understand. Spatio-temporal image correlation spectroscopy (STICS) allows quantification of the magnitude and direction of flow of fluorescently tagged proteins inside living cells. This is done through computation of the space-time correlation function of the intensity recorded in image series acquired via standard fluorescence microscopy. However, this powerful technique is often hindered by a high concentration of immobile particles in cells. New methods overcoming this problem will be developed in this thesis.We start by creating a theoretical framework for spatio-temporal correlation functions. This allows easy extension to more complex type of kinetics, but more importantly, it constitutes the basis for our new techniques. Most of these techniques share a common characteristic: they rely on the time frequency space to separate populations of particles with different transport properties from each other. Effectively, slow dynamics are concentrated in the low frequencies, allowing extraction of faster dynamics for a minority population.The first approach we propose is based on the theory of discrete-time signal processing. We use a highpass first-order Butterworth infinite-impulse response (IIR) filter on a pixel-per-pixel basis to select the dynamics we are interested in from a particular data set. Via a dimensionless analysis, we show a first approximation on how this filter will affect measurements of flowing and diffusing populations of particles. This filter can be tuned to select particular dynamics and, in contrast to a previously developed filter, does not depend on the length of the time series to be analyzed. An alternative analysis is to look at only the asymmetric part of the correlation function, since flows are the only asymmetric component.The second approach is to look directly in temporal frequency space, or nu-space. Two new spaces of analysis are introduced, nu-space image correlation spectroscopy (nICS) and k-nu-space image correlation spectroscopy (knICS) for its spatial reciprocate. We derive the form of the correlation function for simple dynamics in knICS. In nICS, due to analytic difficulties we simply derive the form for a simple flow.Finally, we use numerical simulations to show the validity of our approaches and explore the strengths and limits of the newly developed techniques. We show that they are only moderately affected by immobile concentration, noise and other background populations. However, the ratio of flow to the diffusion coefficient in biased diffusion is the major constraint. Two new parameters which were previously not accessible with image correlation analysis are extracted from simulations, the diffusion coefficient of a biased diffusion and flow density.This thesis provides new image correlation tools, which complement existing ones, that promise to shed light on the complicated inner workings of the cell.Le transport et l'adressage de protéines sont des procédés essentiels pour la cellule; leur compréhension est donc primordiale. La spectroscopie de corrélation spatio-temporelle d'images (spatio-temporal image correlation spectroscopy, STICS) permet la quantification de l'amplitude et de la direction du débit de protéines fluorescentes à l'intérieur de cellules vivantes. Ceci est possible à l'aide du calcul de la fonction de corrélation spatio-temporelle d'une série d'images acquises à l'aide d'un microscope à fluorescence standard. Par contre, cette technique est souvent limitée par de hautes concentrations de particules immobiles. De nouvelles méthodes pour surmonter ce problème seront développées dans ce mémoire. Nous commencerons par développer un cadre théorique pour les fonctions de corrélation spatio-temporelle. Ceci nous permet de généraliser facilement les méthodes pour prendre en compte des dynamiques plus complexes, mais, surtout, ceci constitue la base pour nos nouvelles techniques. La plupart de ces méthodes partagent une caractéristiques communes: elles utilisent les fréquences temporelles afin de séparer les populations possédant des propriétés de transport différentes. En effet, les dynamiques lentes sont situées dans la région des basses fréquences, permettant ainsi l'extraction de dynamiques rapides de populations minoritaires. La première approche que nous proposons se base sur la théorie du traitement de signal à temps discret. Nous utilisons un filtre passe-haut de type Butterworth de premier ordre (réponse à une impulsion infinie, infinite-impulse response, IIR) appliqué sur chaque pixel afin de sélectionner les dynamiques recherchées dans nos données. À l'aide d'une analyse adimensionnelle, nous montrons une première approximation de l'effet de ce filtre sur des populations de flux et de diffusion. Une analyse alternative est d'isoler la partie asymétrique de la fonction de corrélation, puisque seulement les populations de flux s'y retrouvent.La deuxième approche est d'inspecter directement l'espace des fréquences temporelles, ou l'espace nu. Deux nouveaux espaces d'analyse sont présentés, la spectroscopie de corrélation d'images dans l'espace nu (nu-space image correlation spectroscopy, nICS) et la spectroscopie de corrélation d'images dans l'espace k-nu (k-nu-space image correlation spectroscopy, knICS). Nous dérivons la forme de la fonction de corrélation pour des dynamiques simples pour knICS mais, dues à des difficultés analytiques, nous présentons seulement la forme de la fonction d'un flux pour nICS. Enfin, nous utilisons des simulations numériques afin de montrer la validité de nos approches en plus d'explorer les forces et les limites de chacune d'entre elles. Nous montrons qu'elles sont peu affectées par la concentration de particules immobiles, le bruit et les autres populations d'arrière-plan. Néanmoins, le ratio entre la vitesse et la diffusion pour une diffusion biaisée émerge comme une contrainte majeure. Deux nouveaux paramètres précédemment non accessibles aux techniques d'imagerie de corrélation sont extraits soit le coefficient de diffusion d'une diffusion biaisée ainsi que la densité de flux. Ce mémoire fournit de nouveaux outils d'imagerie de corrélation, complétant ainsi les techniques pré-existantes, qui promettent de faire la lumière sur le fonctionnement complexe des cellules.
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Gulick, Sidney Luther. "Ion injection into radio frequency quadrupole field devices." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66038.
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Yakout, Ahmed Hassan. "Transient frequency control options for future power systems." Thesis, University of Strathclyde, 2010. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=13223.
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Gardner, Kyle Scot. "Single frequency vertical external cavity surface emitting lasers." Thesis, University of Strathclyde, 2007. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21733.
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The thesis presents the development and implementation of single frequency vertical external cavity surface emitting lasers (VECSELs). Numerous cavity designs are reported, exploiting some unique features for single frequency operation. A small VECSEL cavity configuration is reported utilising a positive curvature mirror in reverse to create a 6mm cavity where the air gap between the mirror surface and VECSEL wafer act as an etalon, which induces single frequency operation. A 7nm tuning range has been shown with maximum output of 19.4mW. Thermal modelling was undertaken to analyse how the removal of the VECSEL's substrate could increase the thermal efficiency for high power operation. Another small cavity design of length 50mm was created, producing a high power, compact single frequency VECSEL. Using a birefringent filter and solid etalon single frequency operation was achieved. A tuning range of 1Onm was achieved with output powers of 271mW. Extensive mapping of the pump profile and eventual manipulation of this resulted in the Mp2s of the laser of 1.1 being reduced to 1.02. In addition an air etalon system was constructed to eliminate walk-off losses experienced by the solid etalon. This resulted in a 20nm tuning range. Frequency doubling of an 850nm VECSEL using KNbOb3s is reported with 1.3mW of 425nm being achieved, corresponding to an efficiency of 3.2%/W. This system also incorporates a polarisation coupled pump system delivering 3W at 670nm from a 100(So(Bm fibre. The relationship between the VECSEL's gain and frequency conversion efficiency is also analysed in detail.
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Li, Min. "Robust topological design of low frequency electromagnetic devices." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121229.
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This thesis presents an automated topological design system for low frequency electromagnetic devices, e.g. an interior permanent magnet motor. The automated design is carried out through a topological shape optimization process: first, the system employs a topological sensitivity analysis to examine the design domain and to determine the optimal topology (distribution of source and materials); second, the system uses a shape optimizer to further improve the design; these two steps are performed alternately until the optimality condition is satisfied. The robustness of a topology with respect to small variations on its geometries is studied and a robustness measure is defined, originally in the thesis, as the worst case performance of an objective function for the topology and shape optimization. Therefore, the idea of robust design can be applied to the conceptual design (topological design) of electrical machines. Other than the application to motor design, the topology optimization algorithm developed in the thesis, was used originally in the non-destructive testing for quickly location and accurately shape reconstruction of cracks.Cette thèse présente un système automatique de conception topologique pour les dispositifs électromagnétiques à basse fréquence, par exemple, un moteur à aimant permanent intérieur. La conception automatisée est effectuée par un processus d'optimisation topologique de la forme : d'abord, le système emploie une analyse de sensibilité topologique pour examiner le domaine de la conception et déterminer la topologie optimale (répartition des sources et des matériaux); Deuxièmement, le système utilise une optimisation de forme pour améliorer la conception, les deux étapes étant effectuées alternativement jusqu'à ce que la condition d'optimalité est satisfaite. La robustesse de la topologie par rapport à de petites variations est étudiée et une mesure de robustesse est défini, à l'origine dans cette thèse, comme la performance de la fonction objectif, dans le pire des cas, pour l'optimisation topologique de la forme. Le concept de conception robuste peut donc être appliquée à la conception (conception topologique) des machines électriques. Autre que l'application de la conception du moteur, l'algorithme d'optimisation topologique, développé dans la thèse, a été utilisé à l'origine dans le contrôle non destructif pour trouver rapidement les fissures et preciser la forme optimale.
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Tant, Katherine M. M. "Time-frequency domain modelling for ultrasonic nondestructive testing." Thesis, University of Strathclyde, 2014. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=24448.
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This thesis endeavours to develop and implement new and improved methods for the characterisation of defects embedded in steel welds through the analysis of data collected by ultrasonic phased array inspections. A factor common to the existing imaging techniques used for flaw characterisation is the subjective thresholding required to estimate the size of the flaw. The work contained in this thesis uses the mathematics of inverse problems and scattering theory to extract information about such defects and puts forward an objective approach which employs a mathematical model. A relationship between the pulse-echo response curve of a scattering matrix and the size and orientation of a flaw is derived analytically via the Born approximation and results in a completely objective approach to crack sizing. Further expansion of these relationships allows for expressions to be formulated concerning the minimum resolvable crack length and the effects of array pitch and flaw depth on the accuracy of the algorithm. The methodology is then extended and tested on experimental data collected from welded austenitic steel plates containing a lack of fusion crack. In the latter part of this thesis, work focusses on the exploration of the fractional Fourier transform and coded excitations. The fractional Fourier transform allows for retention of both time and frequency domain information simultaneously and permits the in homogeneous wave equation (with a forcing function prescribed as a linear chirp modulated by a Gaussian envelope) to be solved in time-frequency space. This in turn facilitates a comparison between a gated continuous wave excitation and a Gaussian modulated linear chirp. It is observed that the Gaussian modulated linear chirp results in a marked increase in the scattering amplitude.
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Skulason, Helgi. "High-frequency characterization and applications of graphene devices." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119524.
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In this thesis, we have experimentally probed the microwave frequency electrodynamics of large area graphene, focussing on contactless measurements of graphene to extract material properties and implementation of non-reciprocal microwave devices. Our goal is to exploit interaction of graphene with electromagnetic waves in the microwave domain.By fabricating wideband graphene coplanar waveguides, we show that graphene has a constant wideband resistance from 17 Hz to 110 GHz due to negligible kinetic inductance and negligible skin effect up to 110 GHz. We characterize contact impedance between graphene and metal electrodes and our devices show that contact capacitance shorts the contact resistance above ~ 2 GHz, allowing for contactless measurements of graphene up to 110 GHz. We measured the magnetoconductance of large-area graphene under microwave excitation by employing Corbino disk geometry via the transfer of graphene films onto polished coaxial flanges. Our experimental setup allows for both passive and active graphene devices where the active devices are doped by field effect with an intrinsic silicon gate electrode transparent to microwaves. Magnetoconductive mobilities of ~ 1,000 cm2/Vs were extracted from a single component Drude model observed at high carrier density. An anomalous microwave magnetoresistance was also observed. We designed, fabricated and characterized a hollow waveguide isolator with a magnetically biased graphene acting as the non-reciprocal element via Faraday rotation. Our experimental setup allows for contactless characterization of conductivity, mobility and charge carrier density of the graphene film. Faraday rotation was measured up to 1.5° which resulted in isolation of 25 dB. We show that performance of the isolator can be improved by increasing carrier mobility in graphene. As the direction of Faraday rotation is contingent on majority charge carrier type in graphene, we give evidence that the isolation direction can be modulated and switched via field effect graphene device implemented in the hollow waveguide using a single low-power voltage source. We demonstrate the first voltage-tunable isolator with a maximum isolation of 47 dB and voltage-tunable isolation up to 26 dB. Our work suggests that other non-reciprocal devices such as circulators can be implemented compactly with graphene.Dans cette thèse, nous avons expérimentalement sondé les micro-ondes électrodynamiques de graphène de grande surface, plus particulièrement les mesures de graphène sans contact pour en extraire les propriétés de la matière et la mise en œuvre de dispositifs non-réciproques générateurs de micro-ondes. Notre objectif consiste à exploiter l'interaction entre le graphène et les ondes électromagnétiques dans le domaine des micro-ondes. En fabriquant un guide d'ondes de graphène coplanaire à large bande, nous établissons que le graphène possède une résistance de large bande constante comprise entre 17 Hz et 110 GHz. Ceci est attribuable à l'inductivité cinétique et à l'effet pelliculaire négligeables jusqu'à 110 GHz. Nous décrivons l'impédance des contacts entre le graphène et les électrodes métalliques. Nos dispositifs démontrent que la capacitance de contact court-circuite la résistance de contact au-dessus de 2 GHz, permettant les mesures du graphène sans contact jusqu'à 110 GHz. Nous avons mesuré la conductivité magnétique du graphène à grande surface sous excitation de micro-ondes utilisant une géométrie de disque Corbino en transférant les films de graphène sur des embouts de câble coaxial polis. Notre installation permet l'utilisation de dispositifs de graphène actifs et passifs où les dispositifs actifs sont dopés par effet de champ avec une grille de silicium intrinsèque transparente aux micro-ondes. Nous avons extrait des mobilités à base de la conductivité magnétique autour de 1000 cm… en utilisant le model de Drude à une composante à haute densité. Une magnéto résistance atypique a également été observée. Nous avons créé, fabriqué et caractérisé un guide d'onde isolateur creux avec du graphène biaisé magnétiquement agissant comme élément non-réciproque par rotation de Faraday. Notre montage expérimentale permet la caractérisation sans contact de la conductivité, la mobilité et la densité de porteurs de charges du film de graphène. La rotation de Faraday a été mesuré jusqu'à 1.5 ce qui résulte en une isolation de 25dB. Nous démontrons que la performance de l'isolateur peut être améliorée en augmentant la mobilité dans le graphène. Étant donné que la direction de la rotation de Faraday dépend du signe du porteur de charge dominant dans le graphène, nous soumettons des données démontrant que la direction de l'isolation peut être modulée et changée en utilisant l'effet de champ implémenté dans le guide d'ondes creux avec une seule source de voltage à basse puissance. Notre travail suggère que d'autres dispositifs non-réciproques comme des circulateurs peuvent être implémentés de façon compacte avec du graphène.
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Sylvestre, Benoit. "Time-scale modification of speech : a time-frequency approach." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60496.
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Time-scale modification (TSM) is a process whereby signals are compressed or expanded in time in a manner which preserves their original frequency characteristics. This work explores TSM algorithms for sampled speech. A known approach (2) which is based on the short-time Fourier transform (STFT) is first reviewed, then modified to provide high-quality TSM of speech signals at a lower computational cost. The proposed algorithm resembles the sinusoidal speech model (SSM) based approach (9), yet incorporates new phase compensatory measures to prevent excessive structural deterioration of the time-scaled signal. In addition, a novel incremental scheme for modifying polar parameters results in substantial computational savings.
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Luo, Changling 1980. "Fluctuating wind power penetration as limited by frequency standard." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=83873.
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Fluctuating wind power is due to wind turbulence and is the part which should be filtered out leaving behind the more predictable mean wind power which can be traded in the hourly energy market. The power fluctuations cause the frequency of electric utility to deviate from the 60Hz standard. This thesis is concerned with estimating the maximum fluctuating wind power before the 1% deviation from the 60 Hz standard (required by some utilities) is exceeded. To keep the thesis manageable, the scope is narrowed to thermal power plants with governor speed control but no Automatic Governor Control (AGC). This thesis shows that each governor speed control system provides energy storage buffer to attenuate the wind power fluctuations and arrives at the estimate that the fluctuating wind power penetration is conservatively around 5% of the generation capacity of the utility grid. The methodologies used to reach this estimate are: (i) Transfer Function analysis of power plants; (ii) digital simulations using HYPERSIM. Through the research, an innovative method of predicting the frequency deviation in an electric grid with multiple power plants has been developed and validated by simulation.The thesis also shows that fluctuating wind power penetration can be higher when there are filtering also in the wind farms. Wind turbines, with small inertias, driving constant speed squirrel cage induction generators are found to provide poor filtering. On the other hand, the fluctuating wind power penetration limit is increased to 18% in the case of wind turbines, with large inertias, driving variable-speed doubly-fed induction generators (DFIG) with decoupled P-Q control to implement optimal wind power acquisition.
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Tsai, Tsung-Yen. "Programmable phase/frequency generator for system debug and diagnosis." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104811.
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A method of analog signal generation is presented that is suitable for most digital test methodologies such as that described by the IEEE 1149.1 test standard. The method can be used to produce a wide range of phase and frequency signals for system test debug and diagnosis. The method involves the generation of a 1-bit periodic bit stream through an off-chip software encoding procedure involving a delta-sigma modulator, followed by an on-chip hardware decoding procedure using a phase-locked loop and a circular register or memory. A method of calculating the output delay for an integer-N PLL is introduced. An experimental hardware prototype operating at 4 GHz implemented in a 0.13 µm CMOS process will be used to illustrate the signaling capabilities of this generator under different test situations. A PCB with the PLL-die bonded directly facilitates the testing of the signal generation system. An off-board pattern generator is used to drive the PLL. Frequency signal generation is used to characterize two striplines in series, while phase signal generation is used to obtain the jitter transfer function of the PLL.Une méthode de génération de signaux analogiques qui est appropriée pour la plupart des méthodes de test digitale comme décrit par le standard de test IEEE 1149.1 est présentée. Cette méthode peut être utilisée pour produire une série de signaux encodés dans la phase et la fréquence à des fins de tests tel que « system test debug » et « system test diagnosis ». La méthode consiste à produire un signal périodique digitale consistant d'une seule valeur binaire à l'aide d'un module « software » externe au circuit intégré et de le décoder dans le circuit intégré à l'aide d'un PLL et une mémoire ou bien un registre circulaire. Le module « software » externe au circuit intégré consiste d'un modulateur Delta-Sigma. Par la suite, une méthode pour calculer le délais du «output » d'un « integer-N PLL » est présentée. Un prototype expérimentale sur circuit intégré CMOS 130nm est utilisé pour démontrer la viabilité de cette méthode à une fréquence de 4GHz. Finalement pour tester le prototype expérimental sur circuit intégré en CMOS 0.13 µm, un PCB a été conçu pour que l'on puisse y attaché le circuit intégré avec du « bond wiring ». Pour le test, un générateur de signaux externes fut utilisé pour modéliser deux « striplines » en série pendant qu'un signal encodé dans la phase fut utilisé pour déduire le « jitter transfer function » du PLL.
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Chan, Antonio. "Circuits for time and frequency domain characterization of jitter." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29532.
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Jitter characterization has become significantly more important for systems running at multi-gigahertz data rates. Time and frequency domain characterization of jitter is thus a crucial element for system specification testing. Time domain jitter measurement on a data signal with sub-gate timing resolution can be achieved using two delay chains feeding into the clock and data lines of a series of D-latches known as a Vernier Delay Line (VDL). An important drawback to the VDL structure is that its measurement accuracy depends on the matching of the various delay elements. Although careful layout techniques can help to minimize these mismatches, it cannot eliminate them completely. As well, due to the nature of the design, a relatively large silicon area is required for silicon implementation. In this work, a novel technique is developed which reduces the silicon area requirements by two orders of magnitude, as well enables the measurement device to be synthesized from a register transfer level (RTL) description. A custom IC was designed and fabricated in a 0.18 mum CMOS process as a first proof of concept. The design requires a silicon area of 0.12 mm2 and measured results indicate a timing resolution of 19 ps. The synthesizable nature of the design is demonstrated using a FPGA implementation. In addition, another custom IC was designed and fabricated in a 0.35 mum CMOS process as a frequency characterization circuit to process and extract information from the data obtained from the VDL. This design occupies a silicon area of 1.83 mm2. As test time is an important consideration for a production test, an extension to this component-invariant VDL technique is provided that reduces test time at the expense of more hardware. Finally, a method for obtaining the frequency domain characteristics of the jitter using the VDL will also be given.
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Kosek, Paul C. "Improved analysis of musical sounds using time-frequency distributions." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=83189.
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The objective of this research is to improve the analysis of musical sounds in comparison to traditional additive analysis, i.e. Fourier Analysis. Namely, the focus of this study is to improve the tracking of time-evolving partials. Traditional analysis methods assume constant amplitudes and frequencies over each successive frame in which a signal is analyzed. Tracking the time-evolution of these partials, however, can require the implementation of complex probabilistic techniques. This thesis presents an alternative method in which the Ambiguity Function, a distribution in both time and frequency, is used to create a clearer, more accurate representation that requires fewer complex methods to track partials. Through the use of a more accurate spectral representation and the inclusion of a chirp rate parameter, partials may be more readily followed based upon spectral parameters alone. This new method that is presented will build upon the traditional methods by first employing Fourier analysis to identify partials, and then utilizing the Analytic Signal and Ambiguity Function to improve individual spectral parameter estimations and partial tracking. The overall intent of this work is that through this method, one may create an improved spectral model that is more useful to musical analysis.
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Meda, Venkatesh. "Integrated dual frequency permittivity analyzer using cavity perturbation concept." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38236.
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Optimal utilization of microwave energy requires more basic knowledge of the dielectric properties of the material under investigation. The dielectric properties of materials subjected to microwaves are known to depend on moisture content, temperature and density of the material as well as the frequency of the applied microwave field. This thesis is focussed on the development and evaluation of the new Permittivity Analyser to measure the dielectric properties of agri-food materials at 915 and 2450 MHz using cavity perturbation concept.In this study, the dielectric properties measuring system was designed and developed using cavity perturbation concept to measure the essential and fundamental parameters of microwave-material interaction; dielectric constant and dielectric loss factor of selected agri-food substances and organic solvents. The TM010 mode of electromagnetic energy was selected and configured to operate at the peakresonant condition for both ISM (Industrial, Scientific and Medical) approved frequencies of .915 and 2450 MHz frequencies. The resonant perturbation cavities were designed, fabricated and tested using the network analyser and the permittivity analyser. High Q (ratio of energy supplied to absorbed) values were reported for both frequencies. Basic calibration of the measurement system was performed using standard media such as air, water and alcohol. Necessary mathematical steps and algorithms were written and integrated into a user-friendly software program (Visual basic 6.0) to carry out the entire measurement.
The dielectric properties (epsilon' & epsilon ″) of materials such as; edible oils---canola, soya and sunflower oils, neem oil/pulp, homogenized milk (1, 2 and 3.25% fat), organic solvents such as ethanol, hexane and their mixtures were determined at various temperatures and frequency (915, 2450 MHz) combinations, using cavity perturbation technique. Linear relationships between the dielectric properties and temperature found in the literature were confirmed to be valid for certain ranges in case of edible oils, organic solvents and milk samples tested with the cavity perturbation method. Repeatibility and variability aspects of the permittivity analyzer at both the frequencies are presented.
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McArthur, James G. "Genetic elements which increase the frequency of gene amplification." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74313.
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Members of the HSAG family of mammalian genomic elements were subcloned into the pSV2-DHFR expression vector and shown to encourage vector amplification in cis when transfected into a variety of cell lines. The interaction of multiple positive acting elements was required for this effect, with the native configuration of these elements in HSAG-1 producing the greatest effect. These positive acting elements; purine-pyrimidine tracts, Alu-like repetitive elements, stem-loop structures, and A+T rich sequences, have been previously associated with "hotspots" for recombination. Analysis of the structure of amplified vector sequences in MTX resistant pSV2-DHFR-HSAG-1 transfectants showed that these cells possessed a greater number of novel-joints indicating that HSAG elements may stimulate local recombination. Other experiments demonstrating an interaction between vector and HSAG sequences support this conclusion. We suggest that the stimulation of local recombination events by HSAG elements during vector amplification produces novel joints which then encourage further amplification.
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Xu, Ying Lin 1975. "OFDMA schemes with diversity in frequency-selective fading channels." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81577.
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By using sufficiently long prefix and orthogonal narrow-band sub-carriers with adaptive bit loading, orthogonal frequency-division multiple-access (OFDMA) can offer high bandwidth efficiency required for broadband wireless access communications in frequency-selective fading channels. However, when deep fading occurs in a frequency slot, it can create data loss in one or more sub-carriers. Diversity techniques could be used to enhance the performance of OFDMA in the presence of deep fades.The research presented in this thesis aims to provide diversity in OFDMA for broadband wireless access communications in frequency-selective fading channels. First, the diversity characteristics in OFDMA are examined to establish the diversity equivalence in the time and frequency domains. Based on these characteristics, suitable techniques to achieve the full diversity gain in OFDMA are developed. When channel information is available to transmitters, a group-optimal adaptive-tone-diversity OFDMA (GO-ATD-OFDMA) scheme that combines adaptive diversity gain and bit loading, is proposed. It is shown that the GO-ATD-OFDMA can offer a better performance than the conventional time-domain Rake receiver. In the case of unavailable channel information, spreading is combined with diversity in the proposed group-spreading OFDMA (GS-OFDMA) scheme to provide both diversity protection and interference suppression. The GS-OFDMA has a comparable performance to the group-orthogonal multi-carrier code-division multiple-access (GO-MC-CDMA) scheme but with a reduced transmitted peak-to-average power ratio (PAR). Performance of the proposed schemes in terms of error rates, spectral efficiency, achievable system throughput, and computational complexity is investigated by analysis and simulations.
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Chartrand, Daniel 1955. "Ventilation by high-frequency body-surface oscillation in rabbits." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75917.
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Ventilation by high-frequency body-surface oscillation (HFBSO) was studied in normal rabbits. Adequate ventilation and acceptable gas exchange took place during HFBSO from 3 to 15 Hz. The tidal volume required to maintain a normocapnic state was established at each frequency studied. Using catheter-tip micromanometers inserted in the esophagus or the superior vena cava, new techniques to measure high-frequency intrathoracic pressure oscillations were developed. Using a gamma-function to fit the thermodilution curve, a new technique was developed to measure the cardiac output in small animals. No detrimental hemodynamic effect was found during HFBSO used either for normocapnic ventilation or with large pressure oscillations (30 cm H$ sb{ rm 2}$O) in the body chamber. Finally, during normocapnic ventilation by HFBSO in normal rabbits, the mechanical behavior of the respiratory system was characterized using transfer impedances.
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Yassaei, Mahshid. "Security and privacy analysis of radio frequency identification systems." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114506.
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Radio Frequency Identification (RFID) technology is widely used for variousapplications from access control to object tracking systems. Automation and fasterservices provided by this technology have striking effects on our daily life. However,there are several security and privacy concerns about RFID systems that remainunsolved. During the past years, several attacks have been designed against MifareClassic and HID iClass, two of the most widely used RFID systems on the market.The aim of this study was to improve the security and privacy mechanisms of RFIDsystems through the development of tools and the methodology of system analysis, inthe hope to find the possible flaws before the adversaries do. As an example, effortswere made to partially analyze OPUS cards (the RFID-enabled public transportationpasses in Montreal) and several security and privacy violating specifications of thesecards were highlighted. It was revealed that the static identification number of thecard is transfered in the anticollision process which can be used to track the cardholder without his consent. In addition, the information about the last three usages ofthe card (the time, the date and the metro/bus station) are transferred unencryptedand before the authentication process. Only a linear conversion is applied to theinformation which can be reversed by a simple application such as the one developedand provided in this study.Furthermore, design modifications to improve the security and privacy level of RFIDsystems were provided. These modifications are categorized based on the cost andthe disruption of service that the application of these modifications imposes to themanufacturing company.Key Words: RFID Systems, Privacy, Security, OPUS CardsLes technologies de radio identification (RFID) sont fortement utilisées dans diverses applications qui vont du contrôle d'accès aux systèmes de traçabilité d'objets. L'automatisation et la rapidité accrue des services que ces technologies rendent possibles ont des effets marqués sur notre vie quotidienne. Cependant, les systèmes RFID comportent de nombreux problèmes de sécurité et de protection de la vie privée qui ne sont toujours pas résolus. Au cours des dernières années, de nombreuses attaques ont été conues contre la puce Classic de MIFARE ainsi que la puce iClass d'HID, deux des systèmes RFID les plus répandus sur le marché. Le but de cette étude est d'améliorer les mécanismes de sécurité et de protection de la vie privée des systèmes RFID par le développement d'outils et la méthodologie d'analyse des systèmes, dans l'espoir de découvrir les failles de sécurité potentielles avant que des adversaires ne le fassent. Par exemple, nous avons procédé à une analyse partielle des cartes OPUS (les cartes qui contiennent les titres de transport en commun utilisés à Montréal, qui font usage de la technologie RFID), et mis en évidence de nombreux éléments des spécifications de ces cartes qui représentent une faille de sécurité ou de protection de la vie privée. Nous avons découvert que le numéro d'identification statique de la carte est transmis durant le processus anticollision, ce qui peut être utilisé pour suivre la trace du détenteur de la carte sans son consentement. De plus, des informations concernant les trois dernières utilisations d'une carte (l'heure, la date, et la station de métro ou d'autobus) sont transmis sans être chiffrés, et avant le processus d'authentification n'ait lieu. Seule une conversion linéaire est appliquée sur l'information, et cette conversion peut être inversée par une simple application telle que celle que nous avons développé au cours de cette étude. De plus, nous présentons des modifications visant à améliorer le niveau de sécurité et de protection de la vie privée des systèmes RFID. Nous classons ces modifications sur la base de leur coût et de la gravité des interruptions de service que l'application de ces modifications ferait subir au manufacturier.Mots clés: Systèmes RFID, protection de la vie privée, sécurité, cartes OPUS
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Bhattacharya, Gautam. "Sparse denoising of audio by greedy time-frequency shrinkage." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=123263.
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Matching Pursuit (MP) is a greedy algorithm that iteratively builds a sparse signal representation. This work presents an analysis of MP in the context of audio denoising. By interpreting the algorithm as a simple shrinkage approach, we identify the factors critical to its success, and propose several approaches to improve its performance and robustness. We also develop several model enhancements and introduce an audio denoising approach called Greedy Time-Frequency Shrinkage (GTFS). Numerical experiments are performed on a wide range of audio signals, and we demonstrate that GTFS denoising is able to yield results that are competitive with state-of-the-art audio denoising approaches. Notably, GTFS retains a small percentage of a signal's transform coefficients for building a denoised representation, i.e., it produces very sparse denoised results.L'algorithme de Matching Pursuit (MP) construit par itérations une représentation parcimonieuse du signal, au prix d'un coût de calcul élevé. Ce mémoire présente une analyse de l'algorithme de MP dans le contexte du débruitage audio. En interprétant l'algorithme MP comme une méthode de contraction simple (simple shrinkage), nous chercherons à identifier les facteurs essentiels à son succès, puis proposerons plusieurs approches afin d'en améliorer les performances et la robustesse. Plusieurs améliorations du modèle seront ainsi développées, et une approche du débruitage audio dénommée Greedy Time-Frequency Shrinkage (GTFS) sera présentée en détails. Des expérimentations numériques appliquées à un large éventail de signaux sonores démontrent que les résultats obtenus par débruitage GTFS s'avèrent compétitifs face aux méthodes de débruitage audio qui constituent l'état de l'art. En particulier, le GTFS ne retient qu'un faible pourcentage des coefficients de la transformée du signal pour en construire une représentation débruitée, et produit ainsi des résultats débruités très compacts.
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Tuthill, John D. "Frequency dependent digital compensation in DSP based FM modulators." Curtin University of Technology, Australian Telecommunications Research Institute, 2000. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=9787.
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This thesis reports original work on digital compensation for frequency dependent transfer characteristics and errors in digital PAM/CPFSK (Pulse Amplitude Modulation/Continuous Phase Frequency Shift Keying) quadrature modulators.A particularly flexible and cost effective approach to the implementation of the base-band section of a radio transmitter is to synthesise base-band signals digitally using a DSP (Digital Signal Processor). This approach is limited, however, by the transfer characteristics and errors in the implementation of practical analogue sub-systems. These practical limitations result in undesirable in-band frequency-dependent shaping of the transmitted signals. In the case of FM (Frequency Modulation) signals, this leads to the generation of unwanted side-lobes in the transmitted RF signal spectrum that interfere with signals in adjacent frequency channels. This results in the transmitted signal failing to meet transmission standards requirements.The digital compensation techniques developed and presented in this thesis allow the reduction of undesirable in-band frequency-dependent signal shaping. It is shown that this enables strict requirements on the spectral emissions from the FM transmitter to be met using a flexible and cost effective DSP based modulator system.The contributions of the thesis are in three primary areas:(i) The development of a structure for frequency dependent digital compensation.(ii) The formulation and solution of an optimisation problem that allows the free parameters within the structure to be determined such that effective reduction of unwanted in-band frequency-dependent signal shaping is achieved.(iii) The development of techniques that allow the digital compensation procedure to be successfully implemented on a practical DSP platform.The new digital compensation structure that is proposed uses two digital FIR (Finite ++Impulse Response) filters in the digital base-band section of the quadrature modulator: one in the in-phase (I) channel and one in the quadrature (Q) channel. The tap-weights of the FIR filters are determined by solving two optimisation problems: one for each channel. The optimisation problems are formulated using a new approach that ensures that the degrees of freedom in the optimisation i.e., the FIR filter tap-weights, are used effectively to meet the objective of reducing in-band frequency-dependent signal shaping in analogue sub-systems further down the transmission path.A characterisation of the solutions to the optimisation problems enables the identification of techniques that need to be adopted to successfully implement the proposed digital compensation on a practical DSP-based system.The digital compensation technique is demonstrated by implementing and testing the technique on a DSP platform. The results of experimental studies are presented which clearly demonstrate that the digital compensation technique leads to substantial reductions in adjacent channel interference.
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Caldera, Manora K. "Combined coding and modulation in frequency-selective mobile communications." Curtin University of Technology, School of Electrical and Computer Engineering, 2000. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=9820.
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Due to constraints on spectrum availability and transmitter power, both bandwidth and power efficient communication techniques are desirable for mobile radio. Continuous phase modulated (CPM) signals have gained attention because of their attractive power spectra (Steele, 1992). It has been shown that the trellis coded modulation (TCM) schemes could provide better bit error rate performances compared to the uncoded schemes (Ungerboeck, 1982). Therefore, the combination of TCM which improves error probability and CPM signals which yield low spectral occupancy is expected to provide good coding and modulation over bandwidth and power limited channels such as the one encountered in mobile radio communications.In this research, a Trellis Coded Modulation (TCM) scheme, which combines convolutional coding and partial response Continuous Phase Modulation (CPM) such as Gaussian Minimum Shift Keying (GMSK), is investigated. Also, this study concentrates on the use of rate-half convolutional codes, and GMSK (B(subscript)0T=0.3). The latter has been adopted in the Global System for Mobile Communications (GSM) system.Appropriate codes are selected assuming Maximum Likelihood Sequence Detection (MLSD) based on the Viterbi algorithm using an extensive computer search. The bit-error-rate (BER) performances of the selected trellis coded GMSK schemes are theoretically evaluated in the presence of additive white Gaussian noise (AWGN) and frequency-flat fading. In the case of fading, the analysis is simplified to assume only amplitude-fading, and without considering the effect of fading on the phase of the received signal.Computer simulations are used to evaluate the BER performances of the proposed trellis coded GMSK schemes in the presence of AWGN and practical impairments, such as sample timing offset and carrier phase errors. Coding gains of up to 2.2dB at a BER of 10(subscript)-3 ++are obtained under ideal sample timing and carrier recovery conditions. This has been achieved without increasing the receiver complexity based on the number of states in the Viterbi decoder, compared to the uncoded GMSK scheme. Furthermore, these coded schemes are more tolerant to sample timing and carrier phase impairments.Also, the BER performances of the proposed trellis coded GMSK schemes have been extensively investigated by computer simulations for frequency-flat and frequency-selective fading channels. In the case of frequency-selective fading, the Viterbi decoding is made adaptive to cater for the channel impulse response variations with time. With this adaptive receiver, the irreducible BERs of the coded scheme is found to be lower than that of the uncoded. Performance improvements are obtained with a trellis coded GMSK scheme using a constraint length 2 code with a Viterbi decoder of 16 states compared to the 128 states required for the uncoded scheme. Further, the coded scheme has shown less sensitivity to carrier phase errors, compared to the uncoded.
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Sun, Yucheng. "Essays in volatility estimation based on high frequency data." Doctoral thesis, Universitat Pompeu Fabra, 2017. http://hdl.handle.net/10803/402831.
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Based on high-frequency price data, this thesis focuses on estimating the realized covariance and the integrated volatility of asset prices, and applying volatility estimation to price jump detection. The first chapter uses the LASSO procedure to regularize some estimators of high dimensional realized covariance matrices. We establish theoretical properties of the regularized estimators that show its estimation precision and the probability that they correctly reveal the network structure of the assets. The second chapter proposes a novel estimator of the integrated volatility which is the quadratic variation of the continuous part in the price process. This estimator is obtained by truncating the two-scales realized variance estimator. We show its consistency in the presence of market microstructure noise and finite or infinite activity jumps in the price process. The third chapter employs this estimator to design a test to explore the existence of price jumps with noisy price data.Basándonos en datos de precios de alta frecuencia, esta tesis se centra en la estimación de la covarianza realizada y la volatilidad integrada de precios de activos, y la aplicación de la estimación de la volatilidad para la detección de saltos en los precios. El primer capítulo utiliza el procedimiento LASSO para regularizar algunos estimadores de matrices de covarianza realizada de alta dimensión. Establecemos propiedades teóricas de los estimadores regularizados que muestran su precisión de estimación y la probabilidad de que revelen correctamente la estructura de red de los activos. En el segundo capítulo se propone un nuevo estimador de la volatilidad integrada que es la variación cuadrática de la parte continua en el proceso de precios. Este estimador se obtiene truncando el estimador de varianza realizado en dos escalas. Demostramos su consistencia en presencia de ruido de microestructura del mercado y saltos de actividad finitos o infinitos en el proceso de precios. El tercer capítulo emplea este estimador para diseñar un test para explorar la existencia de saltos en los precios con ruido.
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Nabki, Frederic. "Silicon carbide micro-electromechanical resonators for highly integrated frequency synthesizers." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=94958.
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A low temperature (<300ºC), low-stress micro-electromechanical systems (MEMS) fabrication process based on a mechanically superior silicon carbide structural layer is outlined. The process is designed for low-cost film deposition and CMOS post-integration, stemming from chemical and thermal compatibility. MEMS beam resonators and arrays are fabricated, and have higher power handling capabilities and operating frequencies, compared to those of similar polysilicon-based resonators. A tuning method based on integrated heaters is introduced, yielding constant insertion loss tuning and wide tuning ranges. Quality factors of up to 1493 and resonant frequencies of up to 26.2 MHz are measured. A MEMS beam resonator model that accounts for electrostatic and mechanical non-linearities, and that may be used in circuit simulators is proposed. The model captures non-linear effects such as resonant frequency shifting and Duffing behaviour. It offers valuable insights into the trade-offs involved in the design optimization of MEMS resonator-based oscillators. Such oscillators are designed using an integrated high gain-bandwidth trans-impedance amplifier (TIA) combined with a resonator. The TIA employs automatic gain control to mitigate the inherent low power handling capabilities and the non-linearities of the MEMS device, thus minimizing their effect on phase noise. A highly integrated 1.7-2.0 GHz digitally programmable fractional-N frequency synthesizer using a MEMS resonator-based oscillator as its frequency reference is presented. Due to the dimensions of the MEMS device (e.g. 25 um by 114 um), the entire system with a total area of 6.25 mm2 can be housed in a small standard chip package. This considerably reduces the form factor and cost of the system, compared to using an external crystal as a reference. The synthesizer has a fine frequency resolution (~11 Hz) in order to allow for high output frequency stability when used with an appropriate control loop. A fully integUne technologie de fabrication de microsystèmes électromécaniques (MEMS) à basse température (<300ºC) incorporant une couche structurelle de carbure de silicium à faible contrainte est décrite. Une implémentation peu dispendieuse et une intégration avec les procédés CMOS qui découle d'une compatibilité chimique et thermique sont possibles. Des micro-résonateurs en forme de poutre et des résonateurs couplés sont fabriqués. Ceux-ci transigent des puissances plus grandes et ont des fréquences de résonance plus élevées comparativement à des structures en poly-silicium. Une méthode pour ajuster la fréquence de résonance avec un élément chauffant intégré est introduite et permet une perte d'insertion constante et une vaste gamme d'ajustement. Des facteurs de qualité allant jusqu'à 1493 et des fréquences de résonance allant jusqu'à 26.2 MHz sont mesurés. Un modèle est conçu pour tenir compte des non-linéarités électrostatiques et mécaniques du résonateur et peut être utilisé au sein d'un simulateur de circuits. Il capture les effets non-linéaires tels l'ajustement de la fréquence de résonance et le comportement de Duffing. Les compromis lors de la conception d'oscillateurs basés sur des résonateurs peuvent être discernés avec ce modèle. Ces oscillateurs sont conçus à l'aide d'un amplificateur de transimpédance qui emploie un contrôle du gain automatique pour réduire l'impact des non-linéarités du résonateur et permet la réduction du bruit de phase. Un synthétiseur de fréquences à division fractionnelle hautement intégré est présenté. Celui-ci couvre la bande de 1.7 GHz à 2.0 GHz et incorpore un oscillateur basé sur un résonateur MEMS pour sa référence de fréquence. Les petites dimensions du résonateur (ex: 25 um par 114 um) confèrent au système une superficie totale de 6.25 mm2 et permettent de le placer dans un boitier. La superficie et le coût du système sont réduits comparativement à un
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Turgeon, Martine. "The influence of log-frequency parallel gliding upon perceptual fusion." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26164.
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It is generally recognized that simple harmonic ratios among partials promote their perceptual fusion. However, the influence of parallel gliding in log frequency upon fusion is not understood. The present experiment investigated fusion in relation to different types of parallel and non-parallel log-frequency motion of three concurrent tonal glides. The main hypothesis was that parallel motion on log-frequency-by-time coordinates favors fusion. It was reasoned that a higher degree of fusion of the glides evokes fewer auditory images. Fusion was thus measured by asking eighteen subjects to rate the number of distinct sounds perceived in various gliding stimuli. On test trials, subjects received a pair of stimuli in succession and had to judge which one contained more sounds and to rate the size of the difference on a 7-point scale. Each stimulus was a complex of three sinusoidal tones, gliding in frequency. Each 1400-ms three-glide complex was either increasing or decreasing in frequency, and the spacing among its components was either small, medium or large. The stimuli were aligned in one of five ways: (1) harmonically related, parallel, and therefore unequally spaced in log frequency, (2) inharmonic, parallel, and equally spaced in log frequency, (3) inharmonic, parallel, and unequally spaced in log frequency, (4) non-parallel and diverging in log frequency, and (5) non-parallel and converging in log frequency. Results showed that more sources were perceived under the three parallel conditions than under the two non-parallel ones (p $<$ 0.00001). Moreover, as the spacing between gliding partials increased, more distinct sounds were heard (p $<$ 0.00001). These results suggest that both spectral spacing and non-parallel log-frequency motion segregate concurrent glides. A multiple regression analysis showed that parallel log-frequency gliding promotes fusion over and above the contribution of average spectral spacing and harmonicity (p $<$.0001). The observed dat
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Collin, Charles Alain. "Effects of spatial frequency overlap on face and object recognition." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36896.
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There has recently been much interest in how limitations in spatial frequency range affect face and object perception. This work has mainly focussed on determining which bands of frequencies are most useful for visual recognition. However, a fundamental question not yet addressed is how spatial frequency overlap (i.e., the range of spatial frequencies shared by two images) affects complex image recognition. Aside from the basic theoretical interest this question holds, it also bears on research about effects of display format (e.g., line-drawings, Mooney faces, etc.) and studies examining the nature of mnemonic representations of faces and objects. Examining the effects of spatial frequency overlap on face and object recognition is the main goal of this thesis.A second question that is examined concerns the effect of calibration of stimuli on recognition of spatially filtered images. Past studies using non-calibrated presentation methods have inadvertently introduced aberrant frequency content to their stimuli. The effect this has on recognition performance has not been examined, leading to doubts about the comparability of older and newer studies. Examining the impact of calibration on recognition is an ancillary goal of this dissertation.
Seven experiments examining the above questions are reported here. Results suggest that spatial frequency overlap had a strong effect on face recognition and a lesser effect on object recognition. Indeed, contrary to much previous research it was found that the band of frequencies occupied by a face image had little effect on recognition, but that small variations in overlap had significant effects. This suggests that the overlap factor is important in understanding various phenomena in visual recognition. Overlap effects likely contribute to the apparent superiority of certain spatial bands for different recognition tasks, and to the inferiority of line drawings in face recognition. Results concerning the mnemonic representation of faces and objects suggest that these are both encoded in a format that retains spatial frequency information, and do not support certain proposed fundamental differences in how these two stimulus classes are stored. Data on calibration generally shows non-calibration having little impact on visual recognition, suggesting moderate confidence in results of older studies.
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Myers, Paul Glen. "Seasonal forcing and low-frequency variability of the thermohaline circulation." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60722.
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A series of numerical experiments are conducted using the Bryan-Cox Ocean General Circulation Model to investigate the potential existence of low-frequency variability of the thermohaline circulation under seasonal forcing. Experiments are performed with different combinations of a seasonal cycle being present or not on the restoring temperature, the surface freshwater flux fields (mixed boundary conditions) and the surface wind forcing.Despite the presence of the forcing on the dominant seasonal timescale, it is found that the system may oscillate at the decadal period or longer. The decadal variability is excited by changes in the net surface density flux which are due to the advection of temperature and salinity anomalies in the model domain. The magnitude of the seasonal cycle also plays an important role in determining the timescale of variability. Violent overturning events may occur on the century timescale under seasonal forcing. The magnitudes of the flushes are reduced compared to those found in similar experiments without the presence of a seasonal cycle.
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Tannir, Dani. "Moments based analysis of intermodulation distortion in radio frequency circuits." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95038.
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One of the key design requirements of communication circuits is that of linearity, and one of the main figures of merit for measuring the amount of nonlinear distortion at the output of Radio Frequency (RF) circuits is the third order intercept point (IP3). There are two general classes of methods for calculating the IP3 of a circuit. The first is analytical and is usually based on Volterra series. This approach is cumbersome and is difficult to automate for arbitrary circuits with arbitrary non-linearities. The second class of methods is based on multi-tone simulations and is general and flexible but requires significant computational cost due to the large number of variables present in the circuit equations and due to the need to perform a steady-state simulation. In this thesis, a new simulation based approach is presented for efficiently computing the value of IP3 and its sensitivity in RF circuits. The approach relies on the numerical computation of the Volterra series terms from the circuit moments by evaluating closed form expressions that link the distortion terms to the moments (The moments are defined as the Taylor series expansion of the system solution with respect to the RF input power). Obtaining the value of IP3 and its sensitivity therefore is reduced to solving a set of linear sparse equations. The new approach is simple to apply, fully automated and presents significant reduction in computational cost over existing simulation based approaches while being as accurate as Harmonic Balance based methods. The thesis consists of three main contributions. The first being the moments based approach for finding the IP3 of mixer circuits, which exhibit strong nonlinearities outside the signal path. The second contribution is a method for computing the value of IP3 using only single-tone inputs, which significantly reduces the size of the system of equations that need to be solved. The third contribution is the adjoint sensitivity computation of IP3 usingUne des conditions essentielles dans la conception de circuits de communication est la linéarité. L'un des principaux facteurs de mérite pour mesurer la distorsion non linéaire des circuits de radiofréquence (RF) est le point d'interception du troisième ordre (IP3). Les méthodes de calcul de l'IP3 peuvent être divisées en deux categories: La première regroupe les méthodes analytiques généralement basées sure les séries Volterra. Cette méthode est difficile à automatiser d'une façon independante de la topologie des circuits et du type de la nonlinéarité. Les méthodes de la deuxième classe sont basées sur des simulations du type Harmonic Balance (HB). Ces méthodes necessitent un coût de calcul élevé en raison du grand nombre de variables dans les équations à resoudre. Dans cette thèse, on présente une approche nouvelle pour l'évaluation de l'IP3. Cette approche est basée sur les méthodes de simulation sans pour autant necessiter la solution des equations Harmonic Balance. Cette méthode repose sur le calcul numérique des termes de la série Volterra à partir des moments du circuit en évaluant les expressions de forme fermée qui relient les termes de distorsion aux moments (les moments sont définis comme l'expansion de la série de Taylor de la solution du système par rapport à la puissance d'entrée RF). L'obtention de la valeur de l'IP3 et sa sensibilité est donc réduite à résoudre un ensemble d'équations linéaires creuses. Cette nouvelle approche est simple à appliquer, entièrement automatisée et présente une grande réduction en calcul par rapport aux approches courrantes basées sur la simulation tout en étant aussi précises que les méthodes basées sur la balance harmonique. Cette thèse comprend trois contributions principales. La première est une approche basée sur les moments afin de trouver l'IP3 des circuits mélangeurs. La deuxième est une méthode de calcul de la valeur IP3 en utilisant une seule$
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Ceja, Gómez Frida. "Setting under-frequency relays in power systems via integer programming." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104711.
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The deviation of the frequency of a power system from its nominal value is a reflection of the mismatch between generation and load. Such deviations are serious and must be monitored and controlled very closely. One major impact of operating outside a narrow range around the nominal frequency is that generators can be damaged. To avoid this, manufacturers set time interval limits for under-frequency operation and when such limits are exceeded, the generator trips. However, unless generator tripping is coordinated with some accompanying load shedding, the system inability to supply its load can be exacerbated resulting in an even worse frequency deviation. Under-frequency load shedding (UFLS) is designed to protect the power system from events leading to a sudden drop in system frequency, when the primary frequency regulation built into the generation system is not enough to bring the frequency back to nominal. Under-frequency load shedding disconnects blocks of load when the frequency drops below given thresholds. However, the conventional design of UFLS schemes is primarily based on experience about the behavior of the system. Basically, trial relay settings are proposed, tested, and revised until a successful UFLS scheme is obtained. This process is tedious, not very systematic, and usually leads to shedding conservative amounts of load. This thesis presents a mixed-integer linear programming formulation of the UFLS relay setting problem. The goal is to render the design of UFLS more systematic, less dependent on trial and error, and less conservative in terms of the amount of load shed.Dans un réseau électrique, l'écart de la fréquence du réseau par rapport à sa valeur nominale est le reflet d'un manque d'équilibre entre la production et la consommation. Ces écarts peuvent avoir des conséquences graves et ils doivent être contrôlés et surveillés de très près. Un impact majeur dans l'opération d'un réseau électrique avec une tolérance large autour de la fréquence nominale est le risque d'endommager les alternateurs. Pour éviter cette situation, les fabricants établissent des délais pour opérer en sous-fréquence et lorsque ces délais sont dépassés, les alternateurs sont automatiquement déconnectés du réseau, ce qui entraîne une plus grande déviation de la fréquence.Le délestage sur le seuil de sous- fréquence est conçu pour protéger le réseau électrique d'événements conduisant à une baisse soudaine de la fréquence du réseau lorsque les réglages intégrés dans le système de production sont insuffisants pour ramener la fréquence à la valeur nominale. Le délestage sur le seuil de sous- fréquence consiste à déconnecter des regroupements de consommateurs lorsque la fréquence descend en dessous d'une certaine limite. Cependant, les manœuvres de délestage sont principalement conçues à partir de l'expérience du comportement du réseau électrique. Les réglages des relais de protection de premières instances sont proposés, testés et modifiés jusqu'à ce qu'une manœuvre de délestage approprié soit obtenue. Ce processus est laborieux, non-systématique, et conduit généralement à un délestage conservateur de la demande. Cette thèse présente une formulation utilisant des techniques de programmation linéaire mixte pour déterminer les réglages des relais de protection de sous-fréquence. L'objectif est de rendre la conception des manœuvres de délestage plus systématique, moins dépendante des méthodes empiriques, et moins conservatrice au point de vue du délestage.
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Chander, Rahul. "Algorithms to detect High Frequency Oscillations in human intracerebral electroencephalogram." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18767.
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Researchers have recently discovered high frequency oscillations (HFOs) of short duration in the 100-450 Hz band using the intracerebral electroencephalogram of epileptic patients (surgical candidates). New tools are being developed to study this phenomenon. The frequent occurrence of HFOs makes a visual identification tedious and time-consuming. Automated screening is much more efficient, repeatable, and objective. We introduced an original baseline selection method and enhanced two published HFO detection algorithms based on filters and wavelets. We then compared their performance to that of a human reviewer. Ten minutes of electroencephalogram from five patients was acquired by filtering in 0.1-500 Hz band and sampling at 2000 Hz. A human reviewer visually identified HFOs that were considered ground-truths to measure the performance of the two algorithms. The sensitivity and false discovery rate of the filter method were 75.9% and 10.6% respectively, while those for the Wavelet method were 70.8% and 13.1% respectively. Our methods provide satisfactory performance for HFO detection.Les chercheurs ont découvert récemment des oscillations haute fréquence de courte durée, dans la bande 100-450 Hz, en utilisant des électrodes intracérébrales sur des patients épileptiques (candidats à la chirurgie). Des nouveaux outils ont été développés pour étudier ces phénomènes. Le nombre élevé de ces oscillations rapides fait de leur identification visuelle une tache fastidieuse. La détection automatique est plus efficace, reproductible et objective. Nous avons mis en place une méthode de sélection originale de la ligne de base et amélioré deux algorithmes de détection basés sur l'utilisation de filtres et d'ondelettes. Nous avons par la suite fait la comparaison entre la performance des algorithmes et celle d'un expert. Dix minutes d'électroencéphalogramme de cinq patients ont été enregistrés avec un filtrage de 0.5 à 500 Hz et une fréquence d'échantillonnage de 2000 Hz. Une revue par un neurophysiologiste des oscillations détectées a permis de mesurer les performances des deux algorithmes. La sensibilité et le pourcentage de fausses détections de la méthode avec filtre sont respectivement de 75.9% et 10.6%, alors que pour la méthode avec ondelettes, la sensibilité et le pourcentage de fausses détections sont respectivement de 70.8% et 13.1%. Notre méthode donne des résultats satisfaisants pour la détection d'oscillations haute fréquence.
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Szubbocsev, Zoltan. "The EM algorithm for frequency selective, quasi-static fading channels /." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=111503.
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A fractional iterative channel estimation and data detection algorithm is proposed for frequency selective, quasi-static MIMO channels. It is shown that due to the correlation of the noise samples after pulse matched filtering and sampling, the complexity of the derived receiver, based on the Expectation-Maximization (EM) algorithm with fractional sampling, is the same as that of the ML receiver, which requires an exhaustive search. It is shown that by using a noise whitening filter to whiten the noise samples, the algorithm can be efficiently implemented using the Viterbi algorithm instead of using an exhaustive search technique. Due to spectral zeros of the autocorrelation function of the noise sequence, noise whitening filter designed by spectral factorization are not practical for the square-root raised cosine pulses and similar shapes. An alternative prediction-error whitening filter is proposed solving the Yule-Walker equations. We analyze the performance of the proposed receiver via numerical simulations. It is observed that when the channel is perfectly known, the performance of the fractional ML receiver, with five-tap whitening filter, is only 0.5 dB worse than that of the optimal ML receiver at a BER of 10-4. When the path delays are fixed and the channel is unknown, the fractional iterative scheme outperforms the symbol rate iterative scheme between 0 and 16 dB, and between BERs of 2 x 10-1 and 2 x 10 -4. With varying path delays, the fractional scheme is better for all simulated SNR values. However, both schemes experience a severe error flooring. Application of the EM algorithm to iteratively estimate frequency selective channels and detect the transmitted information sequence improves the efficiency of pilot symbols. By using additional iterations, the BER is lowered with the same number of pilot symbols. We also compare the performance of the iterative receiver that uses the correct tap covariance matrix with the one that assumes a diagonal covariance matrix. It is observed that with fixed path delays the performance is identical with both models. With varying path delays and fractional sampling the diagonal assumption results in a performance loss of 0.5 dB.**This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation).
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Burt, Graeme C. "Sweep-frequency microwave pulse compression using a helically corrugated waveguide." Thesis, University of Strathclyde, 2004. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21549.
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A new type of pulse compressor based on sweep frequency pulse compression has been developed using a helically corrugated waveguide as a dispersive medium. This structure provides selective coupling between a TE₁₁ travelling wave and a near cut-off TE₂₁ wave, creating an eigenwave where the dispersion characteristics of one mode gradually converts into that of other. As the compressor works far from cut-off the reflections associated with operation close to cut-off are reduced and allows the compressor to be used at the output of a powerful amplifier. An experimental and theoretical study of swept-frequency based pulse compression as well as a theoretical and experimental investigation of the dispersive properties of a circular waveguide with a helical corrugation on its inner surface was carried out. Measurements of the helically corrugated compressor obtained a maximum optimum power compression ratio of 10.9 for a helically corrugated waveguide of length 208.08cm. A 1 kilowatt input pulse with a frequency sweep from 9.60GHz to 9.35GHz over 70ns was compressed by the helically corrugated waveguide. The compressed pulse had a duration of 3ns and gave a compression efficiency of 44%. The helical compressor experiments conducted were the first of their kind to be carried out and were found to be in good agreement with theory. A numerical study of the potential of the helically corrugated waveguide to produce multi-GW output pulses using frequency modulation at the falling edge of a microwave pulse produced from a high-power BWO was investigated.
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Banks, Robert. "A frequency agile approach to air-coupled Lamb wave inspection." Thesis, University of Strathclyde, 1999. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=23370.
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This Thesis describes the design, manufacture and evaluation of a single sided through-air Lamb wave scanner for Non-Destructive Evaluation (NDE). The new scanning system utilises novel wideband piezocomposite transducers and specialised receive electronics to detect and monitor the thickness of faults within the structure under investigation using a frequency agile approach. Based upon the superheterodyne principle, this frequency agility dispenses with the costly requirement for precision manipulation of the transducer alignment, by effectively tuning the system for the thickness of the sample. Several important applications are identified, including defect detection on samples with tapered thicknesses and defect depth characterisation on plates with thickness erosion, in addition to conventional defect evaluation. Through the application of finite element modelling and practical analysis, a new range of wideband composite transducer have been developed which offer a considerable improvement in operational bandwidth in comparison to conventional piezocomposites. Moreover, a specialised ultra low noise heterodyning amplifier was designed and constructed to provide sufficient gain and selectivity to detect the Lamb waves generated in the various structures under examination. Experimental results obtained from the prototype system illustrate a capability to distinguish defects within test specimens of differing materials and determine the thickness of the given defect. The current system is capable of resolving defects down to less than 2mm in diameter or 20% thinning in a 1mm thick aluminium plate for a Lamb wave with a wavelength of 3mm. Moreover, the handheld nature of the scanning head employed within this system has facilitated the examination of practical NDE examples, such as disbonds between vehicle support structures and outer panelling over curved structures.