Dissertations / Theses on the topic 'Signal variation'
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Wissner-Gross, Zachary Daniel. "Signal variation in single particle aerosol mass spectrometry." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40921.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2007.Includes bibliographical references (p. 33-34).
Rapid and accurate detection of airborne micro-particles is currently an important problem in national security. One approach to such detection, bioaerosol mass spectrometry (BAMS), is currently under development at Lawrence Livermore National Laboratory. BAMS is a type of single particle aerosol mass spectrometry that rapidly records dual-polarity mass spectra of aerosolized micro-particles. However, the accuracy of the BAMS system is limited by various uncertainties, resulting in shot-to-shot variations in the mass spectra. I found that the variations in mass peak areas in BAMS spectra were significantly larger than those predicted by Poisson statistics based on the mean number of detected ions. Furthermore, these variations were surprisingly consistent as a function of peak area among synthetic, organic, and biological samples. For both positive and negative ions, the standard deviation in a peak's area was approximately proportional to the mean value of that area to the 0.9 power. Using the consistency of this data, I also developed a novel method for quantitatively evaluating the similarity between mass spectra using a chi-square factor. Peak area variations in other single particle aerosol mass spectrometers may be similarly analyzed and used to improve methods for rapid particle identification.
by Zachary Daniel Wissner-Gross.
S.B.
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Travis, David J., Vernon Meentemeyer, and Roger P. Belanger. "Stressed Trees Produce a Better Climatic Signal than Healthy Trees." Tree-Ring Society, 1990. http://hdl.handle.net/10150/261930.
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The basis for the selection of trees to be used in the production of dendrochronologies has long been an issue (Douglass 1946; Fritts 1976). In humid regions the common practice has been to use trees that appear to be in good health. As a part of a larger study involving the impact of ice storms on tree-ring increments (Travis 1989), we show that trees stressed as a result of ice damage produced a stronger climatic signal than nondamaged trees.
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McCarter, Rebecca. "Total Variation Based Restoration of Bilevel Waveforms." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/2767.
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A series of Total Variation based algorithms are presented for the restoration of bilevel waveforms from observed signals. The proposed model is discussed analytically and numerically via the gradient descent minimization of the TV energy. The application of restoration of bilevel waveforms encoded within barcode images is presented. A super- resolution technique is proposed as a reduction of dimensionality of the image data. The result is a high resolution image from which the encoded bilevel waveform is restored. Implementation of results is shown for synthetic and real images.
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Cauley, P. Wilson, Seth Redfield, Adam G. Jensen, and Travis Barman. "VARIATION IN THE PRE-TRANSIT BALMER LINE SIGNAL AROUND THE HOT JUPITER HD 189733B." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621234.
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As followup to our recent detection of a pre-transit signal around HD 189733 b, we obtained full pre-transit phase coverage of a single planetary transit. The pre-transit signal is again detected in the Balmer lines but with variable strength and timing, suggesting that the bow shock geometry reported in our previous work does not describe the signal from the latest transit. We also demonstrate the use of the Ca II H and K residual core flux as a proxy for the stellar activity level throughout the transit. A moderate trend is found between the pre-transit absorption signal in the 2013 data and the Ca II H flux. This suggests that some of the 2013 pre-transit hydrogen absorption can be attributed to varying stellar activity levels. A very weak correlation is found between the Ca II H core flux and the Balmer line absorption in the 2015 transit, hinting at a smaller contribution from stellar activity compared to the 2013 transit. We simulate how varying stellar activity levels can produce changes in the Balmer line transmission spectra. These simulations show that the strength of the 2013 and 2015 pre-transit signals can be reproduced by stellar variability. If the pre-transit signature is attributed to circumplanetary material, its evolution in time can be described by accretion clumps spiraling toward the star, although this interpretation has serious limitations. Further high-cadence monitoring at H alpha is necessary to distinguish between true absorption by transiting material and short-term variations in the stellar activity level.
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Rudolf, Robert. "Design methods to mitigate the effects of variation in analogue and mixed-signal circuits." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/374300/.
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The continued scaling of CMOS process features enables ever-faster and denser circuits, which comes at the cost of increased device parameter variation. The performance of analogue and mixed-signal circuits in particular degrades in such a high variation environment, which poses an extraordinary challenge in the design and fabrication of such circuits. This thesis develops a set of tools and methodologies for a post-fabrication calibration system called the Configurable Analogue Transistor (CAT). The principle of the CAT technique is to replace certain transistors in a circuit with calibration devices, which allow adjustment of circuit performance after fabrication to compensate the effects of device parameter variation. Building on initial research on the CAT, this thesis develops a methodology to identify the most suitable calibration devices in their circuit and determine their optimal sizes. Furthermore, the applicability of CAT is extended beyond parameter variation to also include direct compensation of temperature. A complementary technique to post-fabrication calibration is robust design, where a circuit is designed to be inherently robust against variation in device parameters. In this thesis, a novel closed-loop pick-off circuit for force-balanced MEMS accelerometers is presented. It is comparable in performance to other state-of-the-art techniques, but provides vastly improved robustness against parameter variation and a more intuitive design process.
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Page, Jennifer Lynn. "The effects of plume property variation on odor plume navigation in turbulent boundary layer flows." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29752.
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Thesis (Ph.D)--Biology, Georgia Institute of Technology, 2009.Committee Chair: Weissburg, Marc; Committee Member: Hay, Mark; Committee Member: Kubanek, Julia; Committee Member: Webster, Donald; Committee Member: Yen, Jeannette. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Riitters, Kurt H. "Evenness Indices Measure the Signal Strength of Biweight Site Chronologies." Tree-Ring Society, 1990. http://hdl.handle.net/10150/261927.
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The signal strength of a biweight site chronology is properly viewed as an outcome of analysis rather than as a property of the forest-climate system. It can be estimated by the evenness of the empirical weights that are assigned to individual trees. The approach is demonstrated for a 45-year biweight chronology obtained from 40 jack pine (Pinus banksiana Lamb.) trees. The annual evenness of the empirical weights is calculated by indices derived from the Shannon and Simpson diversity indices, and the variances are found by the jackknife procedure. The annual estimates are then averaged to find an overall estimate of biweight signal strength for the 45-year period. These techniques are most useful for determining sample sizes for the biweight procedure, and for comparing different methods of detrending and standardizing data sets prior to applying the biweight mean-value function.
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Ghai, Dhruva V. "Variability-aware low-power techniques for nanoscale mixed-signal circuits." Thesis, University of North Texas, 2009. https://digital.library.unt.edu/ark:/67531/metadc9850/.
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New circuit design techniques that accommodate lower supply voltages necessary for portable systems need to be integrated into the semiconductor intellectual property (IP) core. Systems that once worked at 3.3 V or 2.5 V now need to work at 1.8 V or lower, without causing any performance degradation. Also, the fluctuation of device characteristics caused by process variation in nanometer technologies is seen as design yield loss. The numerous parasitic effects induced by layouts, especially for high-performance and high-speed circuits, pose a problem for IC design. Lack of exact layout information during circuit sizing leads to long design iterations involving time-consuming runs of complex tools. There is a strong need for low-power, high-performance, parasitic-aware and process-variation-tolerant circuit design. This dissertation proposes methodologies and techniques to achieve variability, power, performance, and parasitic-aware circuit designs. Three approaches are proposed: the single iteration automatic approach, the hybrid Monte Carlo and design of experiments (DOE) approach, and the corner-based approach. Widely used mixed-signal circuits such as analog-to-digital converter (ADC), voltage controlled oscillator (VCO), voltage level converter and active pixel sensor (APS) have been designed at nanoscale complementary metal oxide semiconductor (CMOS) and subjected to the proposed methodologies. The effectiveness of the proposed methodologies has been demonstrated through exhaustive simulations. Apart from these methodologies, the application of dual-oxide and dual-threshold techniques at circuit level in order to minimize power and leakage is also explored.
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Hoang, Hung Gia Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "A new variation of the frequency selective Kalman - Yakubovich - Popov lemma with applications in signal processing and control." Publisher:University of New South Wales. Electrical Engineering & Telecommunications, 2008. http://handle.unsw.edu.au/1959.4/43770.
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The Kalman-Yakubovich-Popov (KYP) lemma is a useful tool in control and signal processing that allows an important family of computationally intractable semi-infinite programs in the entire frequency range to be characterized by computationally tractable semidefinite programs. The first part of this thesis presents a new variation of the frequency selective Kalman-Yakubovich-Popov (FS-KYP) lemma for single input single output systems, which generalizes the conventional KYP lemma on given frequency intervals. Based on the transfer function representation of single input single output systems, the proposed FS-KYP lemma provides a unified framework to convert an important family of semi-infinite programs with generic frequency selective constraints that arise from a variety of analysis and synthesis problems for infinite impulse response systems into semidefinite programs. In contrast to existing variations of the FS-KYP lemma, which invariably involves Lyapunov variables of large dimensions, the proposed FS-KYP lemma is free from Lyapunov variables. As a consequence, the proposed semidefinite programs require a minimal number of additional variables, thus can be efficiently solved by general purpose semidefinite programming solvers on a standard personal computer. The second part of this thesis studies several applications of the FS-KYP lemma to control and signal processing. Firstly, we investigate the beam pattern synthesis of an antenna array with bounded sidelobe and mainlobe levels. It is shown that the pattern synthesis problem can be posed as a convex semi-infinite program that is turned into an semidefinite program via the proposed FS-KYP lemma. The attractive feature of the proposed method is that our semidefinite program uses only a minimal number of auxiliary variables. This subsequently enables the design of patterns for arrays with several hundred elements to be achieved on a standard personal computer using existing SDP solvers. Secondly, we develop an efficient method to design several types of digital and analog infinite impulse response filters and filter banks via the new FS-KYP lemma. The proposed method is more flexible than analytical methods in the sense that it allows direct control of more design parameters, which in turn enables more requirements such as degree of flatness to be incorporated into the design process. Finally, we examine some applications of the new FS-KYP to robustness analysis of continuous control systems. Specifically, we introduce a new bisection method to compute the H∞ gain of uncertain polytopic systems.
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Roquin, Claude. "Traitement des données en prospection géochimique : facteurs de variation du signal et sélection de la composante anomale /." Orléans : B.R.G.M, 1985. http://catalogue.bnf.fr/ark:/12148/cb34839296h.
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Goulet, Clément. "Signal extractions with applications in finance." Thesis, Paris 1, 2017. http://www.theses.fr/2017PA01E066.
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Le sujet principal de cette thèse est de proposer de nouvelles méthodes d'extractions de signaux avec applications en finance. Par signaux, nous entendons soit un signal sur lequel repose une stratégie d'investissement; soit un signal perturbé par un bruit, que nous souhaitons retrouver. Ainsi, la première partie de la thèse étudie la contagion en volatilité historique autours des annonces de résultats des entreprises du Nasdaq. Nous trouvons qu'autours de l'annonce, l'entreprise reportant ses résultats, génère une contagion persistante en volatilité à l’encontre des entreprises appartenant au même secteur. Par ailleurs, nous trouvons que la contagion en volatilité varie, selon le type de nouvelles reportées, l'effet de surprise, ou encore par le sentiment de marché à l'égard de l'annonceur. La deuxième partie de cette thèse adapte des techniques de dé-bruitage venant de l'imagerie, à des formes de bruits présentent en finance. Ainsi, un premier article, co-écrit avec Matthieu Garcin, propose une technique de dé-bruitage innovante, permettant de retrouver un signal perturbé par un bruit à variance non-constante. Cet algorithme est appliqué en finance à la modélisation de la volatilité. Un second travail s'intéresse au dé-bruitage d'un signal perturbé par un bruit asymétrique et leptokurtique. En effet, nous adaptons un modèle de Maximum A Posteriori, couramment employé en imagerie, à des bruits suivant des lois de probabilité de Student, Gaussienne asymétrique et Student asymétrique. Cet algorithme est appliqué au dé-bruitage de prix d'actions haute-fréquences. L'objectif étant d'appliquer un algorithme de reconnaissance de formes sur les extrema locaux du signal dé-bruitéThe main objective of this PhD dissertation is to set up new signal extraction techniques with applications in Finance. In our setting, a signal is defined in two ways. In the framework of investement strategies, a signal is a function which generates buy/sell orders. In denoising theory, a signal, is a function disrupted by some noise, that we want to recover. A first part of this PhD studies historical volatility spillovers around corporate earning announcements. Notably, we study whether a move by one point in the announcer historical volatility in time t will generate a move by beta percents in time t+1. We find evidences of volatility spillovers and we study their intensity across variables such as : the announcement outcome, the surprise effect, the announcer capitalization, the market sentiment regarding the announcer, and other variables. We illustrate our finding by a volatility arbitrage strategy. The second part of the dissertation adapts denoising techniques coming from imagery : wavelets and total variation methods, to forms of noise observed in finance. A first paper proposes an denoising algorithm for a signal disrupted by a noise with a spatially varying standard-deviation. A financial application to volatility modelling is proposed. A second paper adapts the Bayesian representation of the Rudin, Osher and Fatemi approach to asymmetric and leptokurtic noises. A financial application is proposed to the denoising of intra-day stock prices in order to implement a pattern recognition trading strategy
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Valeau, Vincent. "Mesure de la vitesse particulaire acoustique par anémométrie laser Doppler : estimation de fréquence instantanée à variation sinusoi͏̈dale, validation de la mesure." Le Mans, 1999. http://www.theses.fr/1999LEMAA006.
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Kegba, Bodio François. "Spectromètre de RMN pour l'étude des solides : automatisation de la variation thermique et traitement du signal de précession libre." Mulhouse, 1989. http://www.theses.fr/1989MULH0129.
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La réalisation d'une instrumentation automatisée, bien adaptée aux problèmes de la résonance magnétique nucléaire des solides, a permis de rendre opérationnel et performant, le spectromètre RMN à impulsions existant au laboratoire. Ainsi l'adjonction d'un dispositif de variation thermique et l'implantation d'un logiciel de gestion, de conduite et de traitement du signal de précession libre, nous a permis d'effectuer des mesures comparatives des temps relaxation T1 et T1ro et du second moment en fonction de la température des composés: hexaméthylbenzène, hexaméthyléthane et de la zéolithe zsm-5
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Hasiniaina, Irène Alida Frankline [Verfasser], Elke [Akademischer Betreuer] Zimmerman, and Sabine [Akademischer Betreuer] Schmidt. "Acoustic signal variation of mouse lemurs : implications for taxonomy and conservation / Irène Alida Frankline Hasiniaina ; Elke Zimmerman, Sabine Schmidt." Hannover : Stiftung Tierärztliche Hochschule Hannover, 2019. http://d-nb.info/1212850793/34.
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Colot, Olivier. "Apprentissage et détection automatique de changements de modèles : application aux signaux électroencéphalographiques." Rouen, 1993. http://www.theses.fr/1993ROUES012.
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La thèse présentée traite du problème de la détection de changements de modèles dans des signaux vectoriels lentement variables. L'étude s'articule autour de deux thèmes: modélisation vectorielle, détection de changements de modèles. Le premier thème est traité sous l'angle d'une technique récursive de modélisation linéaire, tirant profit des propriétés de stationnarité locale des signaux étudiés dans un contexte vectoriel. Dans une seconde partie, le problème de la détection de changements de modèles est étudié. Deux approches sont proposées et testées: la première s'appuie sur un critère d'énergie d'erreurs issues de la modélisation, la seconde est fondée sur la comparaison d'histogrammes approchant des lois de probabilité, les histogrammes étant construits à l'aide d'un critère de type Akaike. La détection de changements de modèles, synonymes de changements de lois, est effectuée à l'aide de mesure de dissemblance. La validation de ces méthodes est réalisée sur des signaux biomédicaux: les signaux électroencéphalographiques
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Zheng, Jiancheng. "Electrical conductivity measurements on ice cores from the Canadian Arctic: An analysis of signal variation within and between ice cores." Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/9520.
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Two ice cores, A93.1 and A93.2, drilled two meters apart at the Agassiz Ice Cap in May of 1993, had on site electrical conductivity measurements (ECM) carried out to determine the confidence limits of the ECM method for chronological and stratigraphic control. Four ECM profiles have been produced from the two cores, one directly on unprepared surfaces of A93.1 and A93.2 and two on a prepared surface of the A93.1 made by a band saw and subsequently planed by a clean microtome knife. The correlation analysis between the two ECM series of whole length ice core on A93.1 prepared and unprepared surfaces gives a correlation coefficient of 0.842. The correlation analysis of whole length of A93.1 and A93.2 cores on the unprepared surfaces gives a coefficient of 0.644. Review of multi-ice core records including $\delta{\sp }$O, ECM and melt percentage, shows that ice on the Agassiz Ice Cap of Canadian High Arctic is continuous from present to the earlier Holocene. (Abstract shortened by UMI.)
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Wang, Zeqi. "A design research study of the effects of process variation on the performance and functionality of a multi-input neural sensor (MINS) IC for neural signal recording." Thesis, Boston University, 2014. https://hdl.handle.net/2144/21272.
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(Thesis: M.Sc.Eng.) PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.In recent years, the effects of process variation have become increasingly more severe as technology has been scaling down in lithographic dimension. This problem also has affected the operation of the MINS IC (Multi-Input Neural Sensor) designed at Boston University by Dr. Lu Wang. This MINS chip was designed for use in both in-vitro and in-vivo applications of measuring and recording neural action potentials and local field potentials in the brains of animals. The MINS chip has been tested and is fully functional, however, with a serious problem of output level shifting from input-to-input due to process variation. This thesis will focus on the study of the effect of process variation on the MINS chip and a proposed method for process variation correction. The effect of process variation on the MINS chip is an extremely serious issue, given the large amount of gain required to sense and record neural signals, especially local field potentials, which have an input voltage of the order of 10-100 μV. The previous version of the printed circuit board designed to correct for process variation can center the output between the upper and lower rails by measuring the required column bias current independently for each of 256 inputs individually and storing these on an FPGA. However, this process variation correction procedure has jeopardized the ability to scan at the required rate in order to record action potentials (spikes). This thesis has two parts: The first part includes the study of the effects of process variation on the functionality of the 8HP MINS chip by doing Gaussian distribution analysis. The second part is the design of a new printed circuit board to increase the speed of the process variation correction procedure in scan mode, and as a goal, to center the output level in both stop mode and scan mode. The study of the effects of process variation on MINS utilizes circuit simulations with the IBM 8HP device models and design kit, using extracted models based on the MINS chip layout. According to the Monte Carlo sampling analysis, only 12 out of 200 samples are showing output level to be around center, with 65% of the samples having output voltage at upper and lower rails. What is more, as the study of 1000 cases shows, a column bias current of about 105uA and/or a bias voltage of 1.212 V, with 3σ to be 3.798uA and 0.131V respectively, is needed to center the output. A new developed version of the variation correction PCB has been designed and fabricated, utilizing a charge pump methodology to quickly charge up (or discharge) the large stabilization capacitor (4.7μF) placed on the Ibias0 node for stability, on the existing MINS PCB. Given that the Ibias0 current on MINS is only around 100μA, a large current of the order of 250-500mA is used in order to achieve the desired scan rate on the chip. A ping-pong approach is used, having two 4.7μF capacitors so that one can be readied while the other is being used for the testing. This PCB design also includes the needed controls with comparators and logic to terminate the charging/discharging operation at the exact correct voltage on the Ibias0 node, for each of the 256 inputs. On this new board, the required voltage at the Ibias0 node (Vbias0) to center the output, instead of Ibias0, will be measured and stored for each of 256 inputs in both stop mode and scan mode.
2031-01-01
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Malki, Maik [Verfasser], Götz S. [Akademischer Betreuer] Uhrig, and Kai Phillip [Gutachter] Schmidt. "Robustness and variation of low-dimensional signal transmission in topological phases / Maik Malki ; Gutachter: Kai Phillip Schmidt ; Betreuer: Götz S. Uhrig." Dortmund : Universitätsbibliothek Dortmund, 2019. http://d-nb.info/1206416238/34.
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Nogueira, Lima Antonio Marcus. "Commande numérique d'une machine asynchrone : contrôle du flux par filtrage stochastique : variation de la vitesse et de la position." Toulouse, INPT, 1989. http://www.theses.fr/1989INPT063H.
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La commande d'un actionneur a courant alternatif utilisant une machine asynchrone a rotor a cage est étudiée. Dans la stratégie de commande, l'opération a flux constant est assurée grâce a une boucle de réglage de la valeur instantanée du flux magnétique, réalise selon une approche originale. L'estimation en temps réel du flux magnétique est obtenue par filtrage stochastique. Le filtre discret de kalman & bucy est développe a partir de la représentation dans l'espace d'état de la machine asynchrone. Les fonctionnements de l'actionneur électrique en régulation de vitesse et en régulation de position sont analyses. Les détails de la synthèse des correcteurs numériques et analogiques employés dans la réalisation de la stratégie de commande sont présentes. Les algorithmes d'estimation et de contrôle numérique sont développes pour une mise en ouvre basée sur un support informatique comprenant un processeur de signal
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Vaillant, Jérôme. "Mesure du tilt atmosphérique à partir de sa variation chromatique pour l'étoile laser polychromatique." Phd thesis, Université Claude Bernard - Lyon I, 2002. http://tel.archives-ouvertes.fr/tel-01025615.
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L'utilisation de grands télescopes rend de plus en plus nécessaire l'emploi de l'optique adaptative qui permet de corriger l'effet de la turbulence atmosphérique. Toutefois cette technique est limitée par le nombre de sources de référence. L'étoile laser permet de pallier ce manque en créant artificiellement une source lumineuse, que l'on peut placer à volonté sur la voûte céleste, au-dessus des couches turbulentes. Or, par cette technique, on ne mesure que les déformations des images mais pas leur déplacement qui est pourtant l'effet le plus important. L'étoile laser polychromatique propose de le corriger également, à partir de la différence chromatique du tilt atmosphérique. Cette mesure différentielle nécessite une grande précision et sa faisabilité n'avait pas encore été démontrée. Pour cela, j'ai conçu et réalisé une expérience dénommée MaTilD (Manipulation de Tilt Différentiel). Le signal à mesurer étant très faible, j'ai développé deux traitements distincts : i) l'estimation des angles d'arrivée par mesure du centre de gravité des images, ii) l'estimation du tilt de la surface d'onde par ajustement d'un modèle sur les images. Le premier traitement m'a permis de mettre en évidence l'existence du chromatisme du tilt. Mais la précision obtenue est inférieure à ce que prédit l'étude théorique que j'en ai faite. Le but du second algorithme est donc d'améliorer cette précision en s'affranchissant d'une partie des limitations de la mesure du centre de gravité : fenêtrage, chevauchement des images, sensibilité élevée au bruit, ... On est alors dans le cadre général de la minimisation de fonctions non-linéaires dans un espace multidimensionnel (typiquement plusieurs dizaines de paramètres). J'ai contribué au développement et aux tests d'une méthode permettant de réduire significativement le nombre de dimensions de cet espace.
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Cowen, Benjamin E. "Bregman Operator Splitting with Variable Stepsize for TotalGeneralized Variation Based Multi-Channel MRIReconstruction." Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1433176806.
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Cruickshank, Mark. "Analysis of CR2/CD21 transcriptional regulation by chromatin structural variation and notch activity in human cell models." University of Western Australia. School of Biomedical, Biomolecular and Chemical Sciences, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0115.
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[Truncated abstract] Human complement receptor 2 (CR2/CD21) is a cell surface glycoprotein detected on specific cells involved in immunity, which binds complement C3 cleavage fragments, cellular ligands IFN-? and CD23 as well as the EBV coat protein, gp350/220. During the early stages of B-cell development CR2/CD21 is silenced. Expression is initiated on immature B-cells escaping negative selection. During peripheral maturation CR2/CD21 is up-regulated with B-cell sub-populations showing distinctive surface levels (comparatively low, intermediate or high). CR2/CD21 is silenced upon terminal plasmacytic differentiation. Appropriate timing and expression level of CR2/CD21 is important for the development of a healthy B-cell repertoire. Previous studies have identified sequences within the proximal promoter and first intron of CR2/CD21 that cooperate within native chromatin to control cell-specific silencing. Further, analysis of cultured human cells has revealed chromatin structural variation causing DNase I hypersensitivity at these regulatory sites in a CR2/CD21-expressing mature B-cell line (Raji) which are absent in a non-lymphoid cell type (K562). The primary focus of the present study involved characterising chromatin structural variation over previously recognized DNase I hypersensitive regions at the CR2/CD21 locus in human cells to understand how chromatin structure might regulate developmental expression of CR2/CD21. ... These studies provide evidence that notch signaling influences CR2/CD21 expression in human cell lines. First, in vivo binding of CBF1 to CR2/CD21 sequences in the proximal promoter and CRS implies that CR2/CD21 is a direct target of notch activation. Second, the effect of exogenous notch signalling molecules on CR2/CD21 proximal promoter activity was modulated by factors binding tandem E-boxes near the transcriptional start site suggesting that the notch pathway may also influence CR2/CD21 expression via control of HLH molecules. Third, initiation of CR2/CD21 expression was observed in a nonexpressing pre-B cell line (Reh) by co-culture with stromal cells expressing a notch ligand (OP9-DL) but not control stroma (OP9-GFP). Together, these findings support a role for notch regulation of B-cell maturation and invite speculation that initiation of CR2/CD21 expression following negative selection of immature B-cells involves crosstalk between HLH transcriptional regulators and the notch pathway. Furthermore, the Reh/OP9-DL co-culture system may provide a model to directly study the relationship between cell signalling molecules, transcription factor regulation, chromatin structural variation and differentiation of B-cells.
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Le, Duff Alain. "Contribution à l'estimation paramétrique de signaux à variation sinusoi͏̈dale de la fréquence instantanée et à amplitude variable : application à l'anémométrie laser Doppler pour l'acoustique." Le Mans, 2003. http://cyberdoc.univ-lemans.fr/theses/2003/2003LEMA1012.pdf.
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L'anémométrie laser à effet Doppler (ALD), dont l'utilisation est très répandue en mécanique des fluides, peut aussi être utilisée pour la mesure de vitesse particulaire acoustique. La nature vectorielle de cette grandeur permet de caractériser les champs à structure complexe ce qui autorise, par exemple, l'étude de phénomènes acoustiques au voisinage de parois vibrantes ou de discontinuités géométriques. L'ALD offre, pour ce type de problème. Le double avantage de présenter une bonne résolution spatiale de la mesure et de ne perttirber que faiblement le champ à explorer. Le Laboratoire d'Acoustique de l'Université du Maine (LAUM) est équipé d'un banc de mesure conçu pour la mesure de vitesse acoustique. Depuis près de huit ans. Les recherches se sont orientées vers la validation expérimentale de cette technique ainsi que vers l'élaboration de méthodes de traitement des signaux propres à extraire la vitesse particulaire dans lin contexte de traitement différé et avec l'hypothèse d'un signal Doppler d'amplittide constante. Cependant, pour que l'ALD soit exploitable efficacement il est indispensable de concevoir un système de mesure. Simple d'utilisation, permettant d'accéder rapidement à la vitesse acoustique et prenant en compte la nature variable de l'amplitude du signal Doppler. L'objectif de cette étude est donc de proposer des méthodes de traitement du signal adaptées à l'estimation de la vitesse particulaire acoustique, dans le cas d'une excitation sinusoi͏̈dale. Et de définir une architecture matérielle et logiciens indispensable à cette mesure. Celle-ci s'opère à partir des composantes en phase et en quadrature du signal Doppler ramené-es en bande de base à l'aide d"un dispositif de démodulation analogique spécialement développé pour cette application. Trois estimateurs sont alors proposés: le premier est basé sur le calcul de la dérivée de la phase du signal Doppler. Sa principale vocation consiste à initialiser une deuxième méthode d'estimation basée sur la recherche du maximum de vraisemblance. Le filtrage de Kalman étendu cmontrent l'influence des paramètres du problème sur la qualité des estimations. Par la suite. Des simulations statistiques de --\,Ionte-Carlo permettent d'évaluer la qualité des trois méthodes. Une estimation sommaire des complexités algorithmiques des estimateurs complète également cette phase dévaluation. Enfin. La validation expérimentale des techniques d'estimation s"articule autour de deux ex- périences Dans un premier temps, la mesure de la vitesse de déplacement sinusoi͏̈dale d'une pointe d'aiguille montée dans un pot vibrant permet de coiifronter les résultats obtenus par ALD à ceux que donne un vibromètre laser. Dans un second temps. La mesure de vitesses particulaires acoustiques rayonnées par un haut-parleur électrodynamique, est proposée. Les valeurs issues de la mesure en champ libre par ALD sont alors coniparées à celles des vitesses de référence obtenues à l'aide de la méthode du doublet microphoniqueLaser Doppler Anemometry (LDA), which is widely used in fluid mechanics, can also be used in order to measure acoustic particle velocity. The knowledge of this vector quantity could be especially useful to characterize a complex acoustic field, allowing for example the study of phenomena close to vibrating surfaces or around duct discontinuities. In addition, LDA ensures, for this kind of problem, theoretically non-invasive velocity measurements with an excellent spatial résolution. The Laboratoire d'Acoustique de l'Université du Maine (LAUM) is equipped with a system designed for acoustic velocity measurement. For nearly eight years, research has been directed towards the experimental assessment of this technique and the development of signal processing methods based on post-processing techniques, with the assomption of a constant amplitude Doppler signal. However, in order to design a more integrated set-up, furthermore easy to manipulate, it is essential to design a system providing real-time measurements of acoustic velocity and taking into account the varying amplitude of the Doppler signal. This research work offers signal processing methods adapted to the estimation of acoustic particle velocity, for a sine-wave excitation, and defines hardware and software architectures suited to this measurement. The latter is performed with the help of the in-phase and the quadrature components of the Doppler signal, which is downshifted thanks to an analog quadrature demodulation technique especially designed for this application. Three estimators are then proposed: the first is based on the Doppler phase derivation, and is the starting point of a second method based on maximum likelihood estimation. The extended Kalman filter is the third method explored. Finally, the approximated, though accurate, analytical forms of the Cramer-Rao bounds show the influence of the parameters on the quality of the estimations. Estimator performance is then illustrated by means of statistical Monte-Carlo simulations. An assessment of the complexity of these algorithms also supplements this evaluation. Finally, the assessment of the estimation technique is obtained thanks to two experiments. Firstly, the measurement of the sinusoidal velocity of the displacement of a needle assembled in a vibration exciter allows the comparison of the results obtained by LDA with those obtained with a laser vibrometer. Then, the measurement of the acoustic particle velocity field radiated by a loudspeaker, is proposed. The measurements obtained in free field by LDA are then compared with the reference velocities obtained using a sound intensity probe
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Magaia, Luis. "Processing Techniques of Aeromagnetic Data. Case Studies from the Precambrian of Mozambique." Thesis, Uppsala universitet, Geofysik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-183714.
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During 2002-2006 geological field work were carried out in Mozambique. The purpose was to check the preliminary geological interpretations and also to resolve the problems that arose during the compilation of preliminary geological maps and collect samples for laboratory studies. In parallel, airborne geophysical data were collected in many parts of the country to support the geological interpretation and compilation of geophysical maps. In the present work the aeromagnetic data collected in 2004 and 2005 in two small areas northwest of Niassa province and another one in eastern part of Tete province is analysed using GeosoftTM. The processing of aeromagnetic data began with the removal of diurnal variations and corrections for IGRF model of the Earth in the data set. The study of the effect of height variations on recorded magnetic field, levelling and interpolation techniques were also studied. La Porte interpolation showed to be a good tool for interpolation of aeromagnetic data using measured horizontal gradient. Depth estimation techniques are also used to obtain semi-quantitative interpretation of geological bodies. It was showed that many features in the study areas are located at shallow depth (less than 500 m) and few geological features are located at depths greater than 1000 m. This interpretation could be used to draw conclusions about the geology or be incorporated into further investigations in these areas.
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Shirke, Chaitrali Dipak. "An extended cell transmission model for arterial traffic and its application to design a robust signal plan." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/135993/1/Chaitrali%20Dipak_Shirke_Thesis.pdf.
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Traffic signals are an integral part of arterial roads, and the performance of optimized traffic signals play a critical role in managing recurrent congestion. The performance efficiency of signal control relies mainly on: a) accuracy and efficiency of traffic flow models that are used to evaluate the performance of different signal plans under various scenarios during signal optimization and b) signal designing technique used for producing signal plans. Hence, this research developed an Arterial Cell Transmission Model (ACTM) for a more realistic simulation of arterial traffic. ACTM is used to develop a Metaheuristic Robust plan Approach (MHRA) to design a robust signal plan that can maintain stable performance under varying traffic demands.
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Narango, Desiree Lynn. "Causes and Consequences of Urban-associated Song Variation: A Study of Vocal Behavior in the Northern Cardinal (Cardinalis cardinalis)." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1337792731.
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Trauernicht, Anna. "Genetic Variation in Janus Associated Kinase 2 and Signal Transducers and Activators of Transcription 3 is Associated with Granulocyte-Macrophage Colony Stimulating Factor Auto-antibodies in Pediatric Crohn’s Disease." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1321370394.
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Estagerie, François-Xavier. "Modélisation comportementale d’amplificateurs de puissance pour les applications radars." Limoges, 2008. http://aurore.unilim.fr/theses/nxfile/default/34fbc763-5a1b-437e-96d2-dfcc53d11c8b/blobholder:0/2008LIMO4027.pdf.
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Ce travail de thèse concerne la modélisation comportementale d’amplificateurs de puissance. Le formalisme choisi, les paramètres S fort-signal, offre à la fois une représentation efficace pour des variations importantes de l’impédance de charge et une procédure d’extraction simple et rapide à mettre en oeuvre. L’intégration de ce modèle dans un environnement de simulation circuit (A. D. S. ) a permis la validation de ce principe grâce à des résultats très probants. Puis son implémentation dans un simulateur système (Scilab/Scicos) finalise la validation de ce modèle “boite noire” dans un environnement de simulation temporel. Dans la dernière partie, un nouveau concept de modélisation comportementale, dite topologique, a été établi. Cette approche est basée sur le design des amplificateurs de puissance, en appliquant un traitement séparé entre les parties actives et passives de l’amplificateur. Ce modèle sera capable à terme de prendre en compte simultanément les désadaptations de charge mais aussi les effets mémoire haute fréquence et thermique présents au sein des amplificateurs de puissanceThis work concerns behavioral modeling of power amplifier. The choosen formalism (nonlinear scattering functions) allows an efficient solution in case of output loading impedance mismatch (until strong V. S. W. R. ) and an obvious and fast identification process. The implementation of this model in circuit environment (A. D. S. ), validates this principle thanks to very good results. Its implementation in system simulator (Scilab/Scicos) concludes the validation of this “black-box model” in temporel environment. In the last part, a new concept of behavioral modeling - topologic modeling - has been established. The approach is directly derived from the topology of the amplifier. Thus, this model is divided into linear and nonlinear sub-models, respectively associated to passive and active elements. This model will be able to take into account in future output loading impedance mismatch but also hight frequency and thermal memory effects into power amplifier
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Abia, Sonny D. "Application of Reliability Analysis to Highway Design Problems: Superelevation (e) Design, Left Turn Bay Design-Safety Evaluation and Effect of Variation of Peak Hour Volumes on Intersection Signal Delay Performance." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/447.
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This research has three parts. Part 1: The Policy on Geometric Design of Highways and Street provides 5 methods of superelevation (e) distribution. Many states use methods 2 and 5 for low speed, urban and rural high-speed facilities. Method 5 aims to address speed variations; but is complicated, computationally intractable and may violate design consistency. Design recommendation by NCHRP439 accounts for speed variation, tractable; but is cumbersome along with irregular/step-wise design curves. New reliability based e distribution method is developed that addresses the speed variation; which is simple in determining and evaluating acceptable required e rates. At 95% level of reliability, the e rate obtained is lower than that from current practice resulting in cost savings. Part 2: Current practice/research does not address safety issue of the left-turn-bay at high degree of saturation (x). Left-Turn-Bay distance has three components: clearance, breaking to a stop and queue. The variation in the queue length reduces clearance and breaking distance resulting in unsafe breaking. Failure = clearance plus breaking distance < demand. The reliability of the left-turn-bay defined as the availability of the three components for left-turning vehicles to complete clearance and breaking maneuver safely; measured as increase in the deceleration rate over limit of 11.2ft/s2, safety index and probability of failure. Results show that at 95% reliability, current design practice fails when x exceeds 50%. Part 3: Current practice uses mean traffic volumes (Vd) as input for traffic signal control at roadway intersections. Variations in traffic flows affect the performance of intersection measured by the delay per vehicle traversing the intersection in seconds. Peak hour factor (PHF), the hourly volume divided by the peak 15-min flow rate within the peak hour is adopted by Highway Capacity Manual (HCM) to control surge. HCM suggests PHF design value of 0.92 for urban and 0.88 for rural areas. Fixed PHF may lead to increase in delay. Effects of variation of peak hour volumes on intersection signal delays are examined with large data. A new model is developed for PHF and Vd and used in signal timing to minimize intersection delay. The results show that the assumption of Poisson distribution for Vd is not reliable; delay reduction of 6.2 seconds per vehicle is achieved. Annual savings in travel time, fuel consumption and emissions cost is estimated in billions of dollars.
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Michoux, Nicolas. "Applications de la théorie des systèmes dynamiques non linéaires à la caractérisation de signaux biomédicaux et à leur modélisation." Rouen, 2000. http://www.theses.fr/2000ROUES009.
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La théorie des systèmes dynamiques non linéaires traite du comportement de systèmes déterministes, dont la sensibilité aux conditions initiales rend impossible toute prédiction à long terme. Les outils de cette théorie, pouvant expliquer les propriétés d'adaptabilité de l'organisme, sont appliqués aux signaux cardiaques, du grêle et vasculaires. La reconstruction de l'espace des états et les applications de 1 e r retour autorisent la caractérisation géométrique de rythmes atypiques et la décomposition des fluctuations du rythme en variabilité multi-temporelles, permettant de distinguer des rythmes fœtaux faiblement variables chez des fœtus en sommeil et en état de souffrance. La quantification des variabilités de la pression dans l'intestin grêle conduit à une distinction entre témoins et sujets dyspeptiques. Les processus de développement de l'organisme engendrent souvent des structures fractales. L'indice d'autosimilarités d'un signal RR donnant une mesure de la variabilité cardiaque, augmente chez des sujets atteints d'une fibrillation. La modélisation par un système d'équations différentielles ordinaires des signaux physiologiques est à envisager dès que des couplages apparaissent entre les variables d'état du système. Il devient possible d'obtenir une modélisation phénoménologique de la variable mesurée. La modélisation de l'ECG mène à la conclusion que le système cardiaque tend à se comporter comme un système dynamique de dimension voisine de cinq. La modélisation de la pression et du diamètre artériel a montré que le système vasculaire était de faible dimension et que le diamètre était l'observable dynamique à retenir. Enfin, l'équivalence difféomorphique consiste à éprouver la connexion entre un objet plongé dans l'espace des phases original et son image plongée dans un espace des états reconstruits, en testant les propriétés mathématiques de transformation de l'un a l'autre. L'équivalence dynamique entre des systèmes chaotiques (Henon, Rossler, Lorenz) et les reconstructions induites par leurs variables est étudiée indépendamment de la dimension de reconstruction. Il en résulte un classement des variables par degré d'observabilité et une discussion sur l'équivalence des variables dans le problème de l'observabilité de la dynamique originale.
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Peterek, Jan. "Časově proměnná filtrace signálů EKG." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220042.
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The aim of this master’s thesis is to create a multiband stop derived from Lynn filters for suppressing mains hum and baseline variation (drift). The first part of the thesis is focused on brief theoretical introduction to the distortion types affecting ECG signal and twelve lead connection. The following practical part describes free realizations of ECG filter and ECG signal filtration. The filter has been tested both on distorted and on non-distorted signal. Finally filters’ error rate was computed from CSE database signals.
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Marim, Marcio. "Applications du Compressed Sensing à l'imagerie biologique de microscopie." Phd thesis, Télécom ParisTech, 2011. http://pastel.archives-ouvertes.fr/pastel-00710395.
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La technique d'acquisition compressée (compressed sensing, CS) est une nouvelle théorie pour l'échantillonnage qui fût introduite afin de permettre l'acquisition ef- ficace de signaux compressibles. Dans cette thèse, nous avons étudié des applica- tions pratiques de cette technique d'échantillonnage, où les acquisitions sont réal- isées dans le domaine de Fourier, menant aux deux principales contributions suiv- antes : (i) Débruitage d'image : Les images microscopiques présentent souvent des dégradations dûs à des artefacts complexes, associés à du bruit ou encore des mauvaises conditions d'éclairage. En microscopie à fluorescence, le bruit et le pho- toblanchiment altèrent la qualité de l'image. Notre travail a consisté à exploiter la théorie d'acquisition compressée comme un outil de débruitage d'image. Nous avons utilisé plusieurs acquisitions aléatoires dans le domaine de Fourier, et la variation totale comme un a priori sur la parcimonie spatiale. La composition des différentes images de reconstruction correspondant aux différents ensembles de mesures aléa- toires renforce la cohérence spatiale de composants du signal significatifs et per- met de décorréler les composants bruités. Nous avons étudié les relations entre la parcimonie d'un signal et les statistiques et la performance pour la réduction du bruit sous différentes conditions initiales de bruitage. Nous avons montré que la technique proposée, basée sur un a priori sur la parcimonie du signal et sur des échantillonnages aléatoires dans le domaine de Fourier, permet d'obtenir des im- ages avec un rapport signal/bruit (SNR) au pire égal à celui obtenu avec les méth- odes de débruitage classiques, tout en utilisant un nombre limité d'échantillons. Sous réserve de pouvoir acquérir l'image dans le domaine de Fourier, le schéma de débruitage proposé fournirait une méthode d'acquisition rapide nécessitant un temps d'exposition moindre, réduisant les effets de photoblanchiment. (ii) Acquisi- tion compressée en microscopie holographique : En microscopie, les données en sortie deviennent considérables, impliquant notamment l'utilisation de capteurs haute-définition (i.e. beaucoup d'échantillons par acquisition) et l'augmentation des temps d'acquisition. La théorie de l'acquisition compressée fournit des outils pour la reconstruction d'images, nécessitant moins d'échantillons que les approches clas- siques. Cependant, les quelques mesures nécessaires doivent être prises dans un domaine incohérent au domaine spatiale, ce qui est difficile à réaliser en microscopie conventionnelle. Nous avons tout d'abord proposé un schéma de calcul permettant l'acquisition de séquences temporelles de mesures d'amplitude dans le domaine de Fourier, et l'estimation de l'information manquante sur la phase par interpolation de spectre de quelques acquisitions complètes d'images. Cette approche a été mise en pratique dans le contexte de l'imagerie rapide, utilisée pour des cellules en mou- vement. Dans un deuxième temps nous avons implanté un schéma d'acquisition compressée pratique, conçu pour l'holographie numérique. Ce schéma permet de mesurer une figure de diffraction du champ optique et reconstruire images de haute qualité à partir de seulement 7% de mesures aléatoires. L'expérience d'acquisition compressée a été étendue avec succès à l'holographie compressée rapide à acquisition unique et dans des conditions d'éclairage faible.
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Kim, Jong Phil. "Efficient confidence interval methodologies for the noncentrality parameters of noncentral T-distributions." Diss., Available online, Georgia Institute of Technology, 2007, 2007. http://etd.gatech.edu/theses/available/etd-04062007-124123/.
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Thesis (Ph. D.)--Industrial and Systems Engineering, Georgia Institute of Technology, 2007.Lewis VanBrackle, Committee Member ; Brani Vidakovic, Committee Member ; Anthony J. Hayter, Committee Chair ; Nicholeta Serban, Committee Member ; Alexander Shapiro, Committee Member.
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Andersson, Gabriel. "Decoding Neural Signals Associated to Cytokine Activity." Thesis, KTH, Matematik (Inst.), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-291559.
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The Vagus nerve has shown to play an important role regarding inflammatory diseases, regulating the production of proteins that mediate inflammation. Two important such proteins are the pro-inflammatory cytokines, TNF and IL-1β. This thesis makes use of Vagus nerve recordings, where TNF and IL-1β are subsequently injected in mice, with the aim to see if cytokine-specific information can be extracted. To this end, a type of semi-supervised learning approach is applied, where the observed waveform-data are modeled using a conditional probability distribution. The conditioning is done based on an estimate of how often each observed waveform occurs and local maxima of the conditional distribution are interpreted as candidate-waveforms to encode cytokine information. The methodology yields varying, but promising results. The occurrence of several candidate waveforms are found to increase substantially after exposure to cytokine. Difficulties obtaining coherent results are discussed, as well as different approaches for future work.Vagusnerven har visat sig spela en viktig roll beträffande inflammatoriska sjukdomar. Denna nerv reglerar produktionen av inflammatoriska protein, som de inflammationsfrämjande cytokinerna TNF och IL-1β. Detta arbete använder sig av elektroniska mätningar av Vagusnerven i möss som under tiden blir injicerade med de två cytokinerna TNF och IL-1β. Syftet med arbetet är att undersöka om det är möjligt att extrahera information om de specifika cytokinerna från Vagusnervmätningarna. För att uppnå detta designar vi en semi-vägledd lärandemetod som modellerar dem observerade vågformerna med en betingad sannolikhetsfunktion. Betingandet baseras på en uppskattning av hur ofta varje enskild vågform förekommer och lokala maximum av den betingade sannolikhetsfunktionen tolkas som möjliga kandidat-vågformer att innehålla cytokin-information. Metodiken ger varierande, men lovande resultat. Förekomsten av flertalet kandidat-vågformer har en tydlig ökning efter tidpunkten för cytokin-injektion. Vidare så diskuteras svårigheter i att uppnå konsekventa resultat för alla mätningar, samt olika möjligheter för framtida arbete inom området.
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Berberkic, Sanjin. "Measurement of small signal variations using one-dimensional chaotic maps." Thesis, University of Huddersfield, 2014. http://eprints.hud.ac.uk/id/eprint/23737/.
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A novel electronic signal Measurement System (MS) based on one-dimensional chaotic maps (Logistic Map (LM) and Tent Map (TM)) has been developed, analysed and tested. Firstly, an in-depth theoretical analysis of each map was performed using MATLAB based computation, and the results demonstrated that the high sensitivity, to initial conditions, of each map was suitable for small signal change detection and measurement. A new 3D representation of chaos map output for varying initial input was also developed allowing the suitability of any one-dimensional chaotic map to be determined. An electronic implementation of the chaotic maps, using low noise and low cost components was developed along with a feedback and a series based MS. The implementations were tested and the experimental results demonstrate a matching within ±1 %, between theory and the electronic implementations, both maps exhibiting behaviour identical to the theoretical maps, ranging from fixed point stability, periodicity and chaos. Each map implementation was tested separately and as part of a complete MS and the results reveal that the proposed measurement technique can detect and measure input signals changes as low as 5 over a 10 V input range, which yields a greater resolution than a MS using an 20 bit Analogue to Digital Converter (ADC) over the same input range. The main advantage of the presented MS is that the accuracy of the measurement is independent of the input range which is not the case with classical approach to measurement based on conditioning circuitry followed by an ADC as the minimum detectable change is directly proportional to the input range.
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Kadlčík, Libor. "Implementace rekonstrukčních metod pro čtení čárového kódu." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220266.
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Bar code stores information in the form of series of bars and gaps with various widths, and therefore can be considered as an example of bilevel (square) signal. Magnetic bar codes are created by applying slightly ferromagnetic material to a substrate. Sensing is done by reading oscillator, whose frequency is modulated by presence of the mentioned ferromagnetic material. Signal from the oscillator is then subjected to frequency demodulation. Due to temperature drift of the reading oscillator, the demodulated signal is accompanied by DC drift. Method for removal of the drift is introduced. Also, drift-insensitive detection of presence of a bar code is described. Reading bar codes is complicated by convolutional distortion, which is result of spatially dispersed sensitivity of the sensor. Effect of the convolutional distortion is analogous to low-pass filtering, causing edges to be smoothed and overlapped, and making their detection difficult. Characteristics of convolutional distortion can be summarized into point-spread function (PSF). In case of magnetic bar codes, the shape of the PSF can be known in advance, but not its width of DC transfer. Methods for estimation of these parameters are discussed. The signal needs to be reconstructed (into original bilevel form) before decoding can take place. Variational methods provide effective way. Their core idea is to reformulate reconstruction as an optimization problem of functional minimization. The functional can be extended by other functionals (regularizations) in order to considerably improve results of reconstruction. Principle of variational methods will be shown, including examples of use of various regularizations. All algorithm and methods (including frequency demodulation of signal from reading oscillator) are digital. They are implemented as a program for a microcontroller from the PIC32 family, which offers high computing power, so that even blind deconvolution (when the real PSF also needs to be found) can be finished in a few seconds. The microcontroller is part of magnetic bar code reader, whose hardware allows the read information to be transferred to personal computer via the PS/2 interface or USB (by emulating key presses on virtual keyboard), or shown on display.
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Fransner, Oscar. "Sediment variations in the Kuchi Lake, southern Taiwan: : Climate signal or tectonics?" Thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-62193.
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Climate archives are of greatest significance when it comes to paleoclimate studies, since these types of archives in a natural way have registered and preserved the conditions of the past. There are several types of climate archives, one of the most commonly used are lake sediments, because lakes can reveal different types of information, for example weathering, vegetation and precipitation. Another reason why lakes are important in climate research is because they are widely spread over the world, and therefore they can be chosen depending on where the focus of the study will be. In this study, -the Lake Kuchi in the southern part of Taiwan, situated at the boundary between the Asian Mainland and the Western Pacific, was used. What makes this densely populated region of the world particularly interesting for climate research is because it is affected not only by monsoons, but also by typhoons and earthquakes. In this paleoclimate study, a total 16 core sections from three different coring points in the Kuchi Lake were analyzed. The main goal was to clarify if the lake could be used as a reliable climate archive, and also interpret the depositional environment of the sediment layers in the cores. All core sections were described and analyzed with the ITRAX XRF-scanner, which lead to the conclusion that the cores consist of a sedimentary sequence of alternating gray clay and dark gray gyttja clay layers, capped by peat, gyttja or clayey gyttja at topmost part. By sieving samples from all different layers, it was observed that some dark gyttja clay layers contained terrestrial organic matter, and hard, angular clay clasts that suggest intense rain falls and flash floods as transportation mechanism. The uppermost part of the cores, from 310 cm to the top layers, consist of homogenous clay and in situ organic matter which indicate calmer depositional environments compared to the alternation between dark gyttja clay and homogenous gray clay. LOI-950 data indicate that the carbonate content of the Kuchi Lake is low, since the weight loss during this temperature is insignificant compared to LOI-550, which stood for the majority of the weight loss. Thus, the sediment sequence in the Kuchi Lake consist of alternation of clays deposited in a calm and relatively deep lake, mixed with layers apparently flushed in from land, possibly due to typhoons. This alternation is capped by organic rich layers, including peat, which indicating filling up of the basin, and shallower conditions.
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Mogili, Roopa. "Temporal variations of IEEE 802.11b signal strengths in an in-building environment." College Park, Md. : University of Maryland, 2003. http://hdl.handle.net/1903/27.
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Thesis (M.S.) -- University of Maryland, College Park, 2003.Thesis research directed by: Dept. of Electrical and Computer Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Åström, Freddie. "A Variational Approach to Image Diffusion in Non-Linear Domains." Licentiate thesis, Linköpings universitet, Datorseende, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-92788.
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Image filtering methods are designed to enhance noisy images captured in situations that are problematic for the camera sensor. Such noisy images originate from unfavourable illumination conditions, camera motion, or the desire to use only a low dose of ionising radiation in medical imaging. Therefore, in this thesis work I have investigated the theory of partial differential equations (PDE) to design filtering methods that attempt to remove noise from images. This is achieved by modeling and deriving energy functionals which in turn are minimized to attain a state of minimum energy. This state is obtained by solving the so called Euler-Lagrange equation. An important theoretical contribution of this work is that conditions are put forward determining when a PDE has a corresponding energy functional. This is in particular described in the case of the structure tensor, a commonly used tensor in computer vision.A primary component of this thesis work is to model adaptive image filtering such that any modification of the image is structure preserving, but yet is noise suppressing. In color image filtering this is a particular challenge since artifacts may be introduced at color discontinuities. For this purpose a non-Euclidian color opponent transformation has been analysed and used to separate the standard RGB color space into uncorrelated components.A common approach to achieve adaptive image filtering is to select an edge stopping function from a set of functions that have proven to work well in the past. The purpose of the edge stopping function is to inhibit smoothing of image features that are desired to be retained, such as lines, edges or other application dependent characteristics. Thus, a step from ad-hoc filtering based on experience towards an application-driven filtering is taken, such that only desired image features are processed. This improves what is characterised as visually relevant features, a topic which this thesis covers, in particular for medical imaging.The notion of what are relevant features is a subjective measure may be different from a layman's opinion compared to a professional's. Therefore, we advocate that any image filtering method should yield an improvement not only in numerical measures but also a visual improvement should be experienced by the respective end-userNACIP, VIDI, GARNICS
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Thomas, Edwin Christopher. "Phase and amplitude variations in the wave fields of ionospherically reflected radio waves." Thesis, University of Leicester, 1986. http://hdl.handle.net/2381/35807.
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The wavefronts of high frequency (HF) radio waves received after reflection from the ionosphere exhibit both spatial non-linearities and temporal variations which limit the performance of large aperture receiving arrays. The objective of this investigation was to measure the phase and amplitude of ionospherically propagated signals in order to relate these parameters to the reflection process. This thesis describes the design and construction of a large aperture multi-element array and its implementation for wavefrot investigations. The hardware and software developed to control the equipment and to record the measurements are described. The procedures required to verify the performance of the experimental system are discussed and results are presented which demonstrate the accuracy of the measurements. The array was utilised for studies of signals received from several transmitters situated throughout Western Europe. The results obtained demonstrate the widely different behaviour of signals received over the various propagation paths and these have been related to the modal content of the received signals. Limited periods existed during which a single ionospheric mode was received and data corresponding to this condition have been compared with those which would be expected if the signal consisted of both a specular component and a cone of diffracted rays. This model is unable to explain the experimental results. Numerical models of the received signal were therefore developed. Results of these and comparisons with experimental results suggest that the measured parameters can be explained by the existence of a specular component with a varying direction of arrival (DOA), plus some contribution from random components. The experimental results indicate that the random or diffracted components normally contribute less than 10% of the received power in a single moded signal.
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Berthezène, Yves. "Etude par irm des variations de signal de l'encephale induites par l'inhalation d'oxygene." Lyon 1, 1994. http://www.theses.fr/1994LYO1M051.
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Souid-Miled, Wided. "Mise en correspondance stéréoscopique par approches variationnelles convexes ; application à la détection d'obstacles routiers." Phd thesis, Université Paris-Est, 2007. http://tel.archives-ouvertes.fr/tel-00738363.
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Cette thèse porte sur la mise en correspondance stéréoscopique ainsi que sur son application à la détection des obstacles routiers à partir d'un système de vision stéréoscopique. La mise en correspondance est une étape cruciale dans la reconstruction de la structure tridimensionnelle de la scène observée. Elle consiste à retrouver les pixels homologues dans deux images prises de deux points de vue différents, et se ramène à un problème d'estimation d'un champ de disparité. La première partie de ma thèse a porté sur l'estimation de la disparité, dans le cadre d'une approche ensembliste, en minimisant une fonction objective convexe sur l'intersection d'ensembles convexes, construits à partir des connaissances a priori et des observations. Dans la plupart des applications de stéréovision, le champ de disparité doit être lisse dans les zones homogènes et les zones faiblement texturées. L'une de nos contributions a consisté à proposer différentes contraintes de régularisation satisfaisant cette propriété. Pour résoudre le problème d'optimisation considéré, nous utilisons un algorithme efficace itératif par bloc. La deuxième partie traite du problème d'estimation de la disparité en présence de changements d'illumination dans la scène observée. Nous considérons pour cela un modèle d'illumination multiplicatif qui permet de compenser les variations spatiales de luminosité de la scène. Enfin, dans la troisième partie, nous appliquons notre méthode d'estimation de la disparité robuste aux variations d'illumination pour la détection des obstacles routiers.
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Yap, San Min Michael. "Analyse statistique de l'impact des variations locales sur les courses de signaux dans une mémoire SRAM embarquée." Montpellier 2, 2008. http://www.theses.fr/2008MON20001.
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Betson, N. R. "Temporal variation in the stable isotope signals of trees with contrasting growth strategies." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596613.
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A long term study of the variation in d12C of bulk leaf material was undertaken under 3 light regimes (3%, 12% and 100% sunlight) using 2 different species displaying contrasting shoot phenologies: Betula pendula Roth. an early successional species with a rapid leaf turnover (“successive” phenology) and Fagus sylvatica L. a late successional species with a single flush of long-lived leaves (“flush” phenology). It was hypothesised that there would be greater seasonal changes in the isotopic composition of the leaves of B. pendula, within a single leaf cohort (due to rapid leaf turnover of that species) and that the different light regimes and shade tolerances of the two species would further extend variation. Physiological and phenological parameters, alongside bulk leaf d13C, were measured over the first growth season (2002) on 4 leaf cohorts in the B. pendula and the single flush of the F. sylvatica. The d13 C of the initial leaf was consistently more enriched in the heavier isotope than bud material. Further changes were observed both within (up to 2‰) and between (up to 4‰) leaf cohorts in both species as well as substantial shifts between light regime (up to 6‰). During the following growth season, measurements were focused at 2 time points: early season and mild season to attempt to explain the variation within leaf cohort and in the change in isotopic signal between the bud and initial leaf. Alongside the continuation of measurements from the previous season, the d13C of the soluble carbohydrates and starch fractions were measured, as well as the d18 O of leaf organic material to follow the mobile carbon fractions as the organic signal changed and to partition the d13C signal into stomatal and biochemical influences. Carbohydrate d13C values showed that the within cohort variation could be explained by fractionation processes during phloem unloading and, later in the season, the progressive incorporation of new carbohydrate with a more negative delta.
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Nisar, Muhammad Mudassar. "Robust low-power signal processing and communication algorithms." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33872.
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This thesis presents circuit-level techniques for soft error mitigation, low-power design with performance trade-off, and variation-tolerant low-power design. The proposed techniques are divided into two broad categories. First, error compensation techniques, which are used for soft error mitigation and also for low-power operation of linear and non-linear filters. Second, a framework for variation tolerant low-power operation of wireless devices is presented. This framework analyzes the effects of circuit "tuning knobs" such as voltage, frequency, wordlength precision, etc. on system performance, and power efficiency. Process variations are considered as well, and the best operating tuning knob levels are determined, which results in maximum system wide power savings while keeping the system performance within acceptable limits. Different methods are presented for variation-tolerant and power-efficient wireless communication. Techniques are also proposed for application driven low-power operation of the OFDM baseband receiver.
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Guo, Yu-yau. "Behavioral modeling and simulaitons [sic] of mixed-signal integrated circuits with process variations and physical defects /." View online ; access limited to URI, 2003. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3115630.
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Suvanto, L. (Leena). "Mate choice and genetic variation in male courtship song in Drosophila montana." Doctoral thesis, University of Oulu, 1999. http://urn.fi/urn:isbn:9514251911.
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Abstract
This thesis deals with factors affecting mate choice as well
as with genetic variation in male courtship song in Drosophila
montana. Males, which produced song with a high carrier
frequency, were found to court females, and also to succeed in
their courtship more often than the males producing low frequency
song. Male mating success correlated with the carrier frequency
of his song recorded after, but not before, an "artificial
winter", which suggests that a sexually selected male
trait is sensitive to environmental factors. A high carrier frequency
of male courtship song correlated positively with the survival
rate of the male's progeny from egg to adulthood (indirect
benefit for the female), but not with the fecundity of his mating
partner (no direct benefit for the female).
The heritabilities and the amount of additive and residual
variation in male courtship song characters were measured in two
populations using father-son regression and sib analysis. The songs
of the males from one of these populations were analysed for a
second time after the cold treatment. Most heritability values
were insignificant, largely due to high residual variation. During
the cold treatment, the additive variation increased and the residual
variation decreased in almost all song traits. Increased variation
in sexually selected traits may help the females to exercise selection between
the males during the mating season of the flies in the wild in
spring. This, and the fact that male song gives the female information
about the male's condition/genetic quality suggests
that in this species the evolution of female preferences for male
song characters could have evolved through condition-dependent
viability selection as postulated by "good genes" models.
Variation and inbreeding depression/heterosis were
studied in traits associated with fly reproduction using inbred
D. montana strains. Songs, hydrocarbons and some behavioural traits
of the flies varied significantly between strains. The strain of
both sexes affected female egg-laying, and the female strain, also,
the survival rate of the flies' progeny, in different
intra- and interspecific combinations. Heterosis was found in the
mating propensity of the flies and in the carrier frequency of
the male song. Diallel analysis revealed unidirectional dominance
towards higher carrier frequency. This direction is the same as
the direction of sexual selection exercised by the females of this
species suggesting that sexual selection could be a driving force
in evolution of this song trait.
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Jones, Alison Marie. "Environmental signals in proboscidean molars : understanding the isotopic variations in enamel and collagen." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325979.
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Bradáč, Pavel. "Multikanálová dekonvoluce obrazů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-218004.
Full textAbstract:
This Master Thesis deals with image restoration using deconvolution. The terms introducing into deconvolution theory like two-dimensional signal, distortion model, noise and convolution are explained in the first part of thesis. The second part deals with deconvolution methods via utilization of the Bayes approach which is based on the probability principle. The third part is focused on the Alternating Minimization Algorithm for Multichannel Blind Deconvolution. At the end this algorithm is written in Matlab with utilization of the NAG C Library. Then comparison of different optimization methods follows (simplex, steepest descent, quasi-Newton), regularization forms (Tichonov, Total Variation) and other parameters used by this deconvolution algorithm.
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Muhammad, Ali Wrya. "Estimation de retards, de facteurs d'échelle et de variations de forme de signaux vectoriels : application aux signaux biomédicaux." Nice, 2001. http://www.theses.fr/2001NICE5605.
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On traite des signaux de type déterministe, inconnus et transitoires. Les applications visées sont les enregistrements, par une grille de capteurs, de Potentiels d'Action qui se propagent tels que l'EMG de surface ou les signaux répétitifs tels que les signaux cardiaques. Dans la première partie, on estime un vecteur de retards en vue d'une estimation de la vitesse moyenne de conduction dans une Unité Motrice musculaire. Pour une vitesse supposée variable le long d'une fibre, l'estimateur des retards est amélioré en utilisant des contraintes sur les retards. On montre ensuite que la variance de l'estimateur de vitesse moyenne est diminuée grâce aux capteurs intermédiaires. On montre également comment varie le biais et la variance de l'estimateur de la vitesse en fonction de la distance entre capteurs. Dans la deuxième partie, on s'intéresse à la forme des signaux : trois mesures de différence de forme sont proposées dans un but de classification et comparées à d'autres existantes. Les mesures proposées se basent sur une distance calculée soit après estimation de la transformation affine qui minimise l'écart de forme, soit en utilisant un domaine invariant par rapport à une transformation affine : l'autocorrélation conserve l'échelle en s'affranchissant des translations, puis la transformée d'échelle permet d'obtenir un domaine invariant par changement d'échelle. (. . . ). Dans la troisième partie, les paramètres de la transformation affine sont considérés comme porteurs d'informations : sous l'hypothèse de l'égalité des formes, l'estimation conjointe de retard et de facteur d'échelle est faite en utilisant une nouvelle méthode rapide et adaptée à la classe des signaux étudiés, notamment à l'EMG de surface pour accéder à la distribution des vitesses de conduction.