The compressive sensing (CS) framework aims to ease the burden on analog-to-digital converters (ADCs) by exploiting inherent structure in natural and man-made signals. It has been demonstrated that structured signals can be acquired with just a small number of linear measurements, on the order of the signal complexity. In practice, this enables lower sampling rates that can be more easily achieved by current hardware designs. The primary bottleneck that limits ADC sampling rates is quantization, i.e., higher bit-depths impose lower sampling rates. Thus, the decreased sampling rates of CS ADCs accommodate the otherwise limiting quantizer of conventional ADCs. In this thesis, we consider a different approach to CS ADC by shifting towards lower quantizer bit-depths rather than lower sampling rates. We explore the extreme case where each measurement is quantized to just one bit, representing its sign. We develop a new theoretical framework to analyze this extreme case and develop new algorithms for signal reconstruction from such coarsely quantized measurements. The 1-bit CS framework leads us to scenarios where it may be more appropriate to reduce bit-depth instead of sampling rate. We find that there exist two distinct regimes of operation that correspond to high/low signal-to-noise ratio (SNR). In the measurement compression (MC) regime, a high SNR favors acquiring fewer measurements with more bits per measurement (as in conventional CS); in the quantization compression (QC) regime, a low SNR favors acquiring more measurements with fewer bits per measurement (as in this thesis). A surprise from our analysis and experiments is that in many practical applications it is better to operate in the QC regime, even acquiring as few as 1 bit per measurement. The above philosophy extends further to practical CS ADC system designs. We propose two new CS architectures, one of which takes advantage of the fact that the sampling and quantization operations are performed by two different hardware components. The former can be employed at high rates with minimal costs while the latter cannot. Thus, we develop a system that discretizes in time, performs CS preconditioning techniques, and then quantizes at a low rate.

In different applications, in digital domain, it is necessary to change the sampling rate by an arbitrary number. For example Software Radio which should handle different conversion factors and standards. This work focuses on the problem of designing and implement sampling rate converters for conversions between arbitrary sampling rates. The report presents an overview of different converter techniques as well as considers a suitable scheme with low implementation cost. The creating VHDL generator of Farrow-based structure to speed up the design process is the main task of this work. The suitable design technique which is the most important thing in any design work is presented in the report as well. The scheme which is considered to be suitable is created by VHDL generator and tested in MATLAB. The source code is attached to the report. And some results from tests of the implemented scheme.

Most discrete time filters use Switched Capacitor structures, but Switched capacitor circuits have finite sampling rate and high power consumption. In this paper we use Switched Current structure to increase sampling rate and reduce power consumption. In this paper, we use a Class-AB structure to compose a double sampling third order low-pass filter. In this paper there are two integrator types. Modified backward Euler and modified forward Euler integrators were realized with double sampling technology from the backward Euler and forward Euler integrators. Compared with other circuits, the circuit has low power supply¡Blow power consumption ¡Bhigh sampling speed. We employ HSPICE and MATLAB to simulate and design the circuit. We use TSMC 0.35£gm process to implement this circuit. The power supply is 1.8V, the cut-off frequency is 3.6MHz, the sampling frequency is 72MHz, and the power consumption is 1.303mW.

<p>In different applications, in digital domain, it is necessary to change the sampling rate by an arbitrary number. For example Software Radio which should handle different conversion factors and standards. </p><p>This work focuses on the problem of designing and implement sampling rate converters for conversions between arbitrary sampling rates. </p><p>The report presents an overview of different converter techniques as well as considers a suitable scheme with low implementation cost. The creating VHDL generator of Farrow-based structure to speed up the design process is the main task of this work. The suitable design technique which is the most important thing in any design work is presented in the report as well. </p><p>The scheme which is considered to be suitable is created by VHDL generator and tested in MATLAB. The source code is attached to the report. And some results from tests of the implemented scheme.</p>

Knowledge gaps related to mass transfer processes involved in passive air sampling of semivolatile organic compounds and factors potentially influencing passive sampling rates (PSRs) were addressed with controlled laboratory experiments, mass transfer modeling, and a field sampling campaign. The observed non-uniform SVOC distributions within porous passive sampling media (PSMs) contradict an assumption in an earlier passive air sampling theory and proved the existence of a kinetic resistance on the PSM side. This resistance can affect PSRs as revealed by a new PAS model which is based on fundamental laws of mass transfer in air and porous media. By considering mass transfer processes within the PSM, the model is able to explain the large variations of field calibrated PSRs with temperature and between SVOC species and the two-stage uptake process, which cannot be addressed by the earlier PAS theory. Because the PSM side kinetic resistance invalidates the assumption that depuration compounds added to the PSM prior to deployment are subject to the same kinetic resistance as the sampled SVOCs, PSRs derived from the loss rates of depuration compounds can differ from the actual PSRs of the sampled SVOCs. Using such PSRs could thus introduce additional uncertainty to PAS-derived air concentrations. Experiments using XAD-resin and silica-gel filled mesh cylinder as PSMs for the uptake of SVOCs and water vapor respectively revealed that sorbent in the inner portion of the PSM does not take part in chemical uptake; PSRs are thus proportional to the interfacial transfer area but not the amount of the sorbent. Accordingly, thinner PSM can be used to reduce the amount of sorbent while keeping or even increasing the PSRs. Optimized designs of PASs could be tested time efficiently using the gravimetrical approach based on water vapor uptake by silica gel.

Knowledge gaps related to mass transfer processes involved in passive air sampling of semivolatile organic compounds and factors potentially influencing passive sampling rates (PSRs) were addressed with controlled laboratory experiments, mass transfer modeling, and a field sampling campaign. The observed non-uniform SVOC distributions within porous passive sampling media (PSMs) contradict an assumption in an earlier passive air sampling theory and proved the existence of a kinetic resistance on the PSM side. This resistance can affect PSRs as revealed by a new PAS model which is based on fundamental laws of mass transfer in air and porous media. By considering mass transfer processes within the PSM, the model is able to explain the large variations of field calibrated PSRs with temperature and between SVOC species and the two-stage uptake process, which cannot be addressed by the earlier PAS theory. Because the PSM side kinetic resistance invalidates the assumption that depuration compounds added to the PSM prior to deployment are subject to the same kinetic resistance as the sampled SVOCs, PSRs derived from the loss rates of depuration compounds can differ from the actual PSRs of the sampled SVOCs. Using such PSRs could thus introduce additional uncertainty to PAS-derived air concentrations. Experiments using XAD-resin and silica-gel filled mesh cylinder as PSMs for the uptake of SVOCs and water vapor respectively revealed that sorbent in the inner portion of the PSM does not take part in chemical uptake; PSRs are thus proportional to the interfacial transfer area but not the amount of the sorbent. Accordingly, thinner PSM can be used to reduce the amount of sorbent while keeping or even increasing the PSRs. Optimized designs of PASs could be tested time efficiently using the gravimetrical approach based on water vapor uptake by silica gel.

In modern digital audio applications, a continuous audio signal stream is sampled at a fixed sampling rate, which is always greater than twice the highest frequency of the input signal, to prevent aliasing. A more energy efficient approach is to dynamically change the sampling rate based on the input signal. In the dynamic sampling rate technique, fewer samples are processed when there is little frequency content in the samples. The perceived quality of the signal is unchanged in this technique. Processing fewer samples involves less computation work; therefore processor speed and voltage can be reduced. This reduction in processor speed and voltage has been shown to reduce power consumption by up to 40% less than if the audio stream had been run at a fixed sampling rate.

Suite à l’utilisation massive et peu contrôlée des pesticides au LIBAN et conformément auxexigences des législations fixées par les réglementations nationales, européennes etinternationales sur la qualité de l’eau, des programmes de surveillances nationaux ont étéélaborés afin d’évaluer la qualité de l’eau dans les milieux aquatiques libanais et de jauger lesimpacts écologiques et sanitaires liés à la présence éventuelle de pesticides dansl’environnement au Liban.Dans le cadre de ces programmes de surveillance, des prélèvements périodiques ponctuelssont réalisés mais, le suivi permanant dans le temps d’une contamination étendue est trèsdifficile ce qui impose alors la multiplication des prélèvements dans le temps et dansl’espace. L’apparition récente des échantillonneurs intégratifs comme alternativesintéressantes aux techniques d’échantillonnage déjà existantes semblent relativement plusefficaces et mieux représentatifs du point de vue économique et environnemental. Ilspermettent d'effectuer un suivi moyenné sur de longues périodes d'observation allant dequelques jours à plusieurs semaines associé à une simplicité d'usage et une réduction descoûts.Le POCIS (Polar Organic Chemical Integrative Sampler) est le type d’échantillonneur adoptédurant nos travaux de thèse afin d’étudier l’applicabilité de ces POCIS au dosage des résidusde pesticides dans les milieux aquatiques libanais. Cent-neuf molécules appartenant àdifférentes familles de pesticides fréquemment utilisés par les agriculteurs libanais ont étéretenues pour l’étude. Les cinétiques d’adsorption des molécules sur les POCIS et celle de ladésorption des composés références de performance « PRC » ont été suivies par calibrationin-situ ou au laboratoire soit en flux statique ou en flux continu sous différentes conditionsayant une influence sur la rétention des pesticides.Le coefficient d’échantillonnage Rs (L.j-1) spécifique à chaque molécule, nécessaire au calculde la concentration moyenne dans le milieu d’exposition du POCIS, a été déterminé dans lesdivers milieux d’étude : Eau minérale, eau de robinet et eau de rivière. Les cinétiquesd’adsorption des molécules ont également été élaborées afin d’évaluer la durée optimaled’implantation dans les différents milieux aquatiques.Après validation du système d’échantillonnage au laboratoire, son efficacité a été vérifiée surle terrain, les POCIS ont été testés in-situ sur divers sites appartenant aux différentes régionsagricoles libanaises (Estuaire de la rivière Ibrahim, Lac Qaraoun, et Rivière Hasbani). Lesconcentrations moyennes de la totalité des pesticides ciblés ont été estimées et leurs valeursont été comparées avec celles obtenues par prélèvements actifs. Cependant, pour le futur, desétudes élaborées devraient être entreprises afin de couvrir la majorité des molécules activesde pesticides employés au Liban; il faudrait également essayer d’améliorer la reproductibilitédes POCIS pour les analyses quantitatives par l’incorporation de nouveaux composésréférences de Performance (PRC) ou par calibration in-situ systématique pour les différentssites étudiés. / Following the massive uncontrolled use of pesticides in Lebanon and to satisfy therequirements of legislative frameworks and directives concerning water quality, nationalmonitoring programs have been developed in order to evaluate the water quality in theaquatic Lebanese media and to evaluate the environmental and health impacts associated withthe presence of these nominated pesticides in the Lebanese aquatic environment.In this context, monitoring programs rely on collecting discrete grab, spot or bottle samplesof water at a given time providing only a snapshot of the levels of pollutants at the time ofsampling. However, the continuous monitoring using active sampling of this widespreadcontamination is very difficult requiring the increase of sampling frequency which iseconomically, logistically and spatially difficult. Wherefore, the integrative samplers arerecently developed as alternative approach to the existing sampling techniques to berelatively more effective and more representative economically and environmentally. Theycan perform an averaged follow-up over long observation period from a few days to severalweeks associated with ease of use and low costs.The POCIS (Polar Organic Chemical Integrative Sampler) is the type of sampler adoptedduring our thesis in order to study the applicability of this device to the evaluation ofpesticide residues levels in the Lebanese aquatic environments. One hundred nine moleculesbelonging to different families of commonly used pesticides by Lebanese farmers wereselected for the study. The kinetic adsorption constants of targeted pesticides and the kineticdesorption constants of Performance Reference Compounds "PRC" were estimated by POCISin-situ or laboratory (static or continuous flow) calibrations under different conditionsaffecting pesticides retention over POCIS receiving phase.To calculate the average concentration in the exposure media, the sampling rate (L/day),specific to each target pesticide was determined in different water studies: mineral, tap andriver water. The kinetic adsorption constants of molecules have also been determined toassess the optimal deployment duration in different aquatic environments.After validation of the sampling system in the laboratory, its effectiveness is tested in field.POCIS were tested in-situ at various sites belonging to different Lebanese agriculturalregions (Ibrahim Estuary River, Qaraoun Lake and Hasbani River). The mean concentrationsof total targeted pesticides were estimated and their values were compared with thoseobtained with active samples. However, further challenges are to cover the majority of activemolecules of pesticides used in Lebanon and to improve the reproducibility of these POCISfor quantitative analysis by incorporating new Performance Reference Compounds (PRC) orextending the implementation of in-situ calibration.

The objective of this dissertation is to investigate GLR control charts based on a sequential sampling scheme (SS GLR charts). Phase II monitoring is considered and the goal is to quickly detect a wide range of changes in the univariate normal process mean parameter and/or the variance parameter. The performance of the SS GLR charts is evaluated and design guidelines for SS GLR charts are provided so that practitioners can easily apply the SS GLR charts in applications. More specifically, the structure of this dissertation is as follows: We first develop a two-sided SS GLR chart for monitoring the mean μ of a normal process. The performance of the SS GLR chart is evaluated and compared with other control charts. The SS GLR chart has much better performance than that of the fixed sampling rate GLR chart. It is also shown that the overall performance of the SS GLR chart is better than that of the variable sampling interval (VSI) GLR chart and the variable sampling rate (VSR) CUSUM chart. The SS GLR chart has the additional advantage that it requires fewer parameters to be specified than other VSR charts. The optimal parameter choices are given, and regression equations are provided to find the limits for the SS GLR chart. If detecting one-sided shifts in μ is of interest, the above SS GLR chart can be modified to be a one-sided chart. The performance of this modified SS GLR chart is investigated. Next we develop an SS GLR chart for simultaneously monitoring the mean μ and the variance 𝜎² of a normal process. The performance and properties of this chart are evaluated. The design methodology and some illustrative examples are provided so that the SS GLR chart can be easily used in applications. The optimal parameter choices are given, and the performance of the SS GLR chart remains very good as long as the parameter choices are not too far away from the optimized choices. / Ph. D.

L'estimation des abondances de population est essentielle pour comprendre les dynamiques de population, les interactions entre espèces et estimer les risques de transmission d'agents pathogènes dans les populations. Plusieurs méthodes d'échantillonnages, basées sur des hypothèses spécifiques permettent d'estimer ces abondances : les méthodes par comptages uniques, par « distance sampling », par échantillonnages successifs ou par capture marquage recapture. Nous nous sommes intéressés à l'abondance des tiques Ixodes ricinus, vecteurs de nombreux agents pathogènes. Cette abondance est classiquement estimée par le nombre de tiques capturées lors d'échantillonnages uniques réalisés sur différentes unités d'observation. Cependant, de nombreuses études remettent en cause cette hypothèse forte et suggèrent que le taux d'échantillonnage est variable selon les conditions d'échantillonnage (type de végétation,…) mais ne prennent pas en compte ce taux d'échantillonnage pour autant. A partir d'une méthode d'échantillonnage par « removal sampling » (RS), (i) nous avons montré que les conditions environnementales influençaient le taux d'échantillonnage et l'indicateur d'abondance usuel i.e. le nombre de tiques capturées lors d'un seul échantillonnage (ii) nous avons proposé une méthode pour détecter l'indicateur d'abondance, basés sur le nombre cumulé de capture, le moins soumis aux variations du taux ; (iii) par une approche Bayésienne hiérarchique, nous avons estimé simultanément l'abondance de tiques des unités d'observation et la valeur du taux d'échantillonnage en fonction du type de végétation et de l'heure d'échantillonnage. Nous avons montré que le taux d'échantillonnage sur des arbustes (entre 33,9 % et 47,4%) était significativement inférieur au taux d'échantillonnage sur des feuilles mortes (entre 53,6 % et 66,7%). De plus, nous avons montré que le modèle RS tend vers un modèle de Poisson iid lorsque la taille de la population N0 tend vers l'infini ce qui pose des problèmes d'indétermination pour estimer les paramètres N0 et τ, le taux d'échantillonnage. Nous avons également montré que (i) les estimateurs Bayésiens divergent lorsque les lois a priori sont des lois vagues ; (ii) les lois a priori β(a, b) avec a > 2 sur τ conduisaient à des estimateurs Bayésien convergents. Enfin, nous avons proposé des recommandations quant au choix des lois a priori pour τ afin d'obtenir de bonnes estimations pour N0 ou pour τ. Nous discutons de la pertinence des méthodes RS pour les tiques et des perspectives envisageables pour (i) estimer le risque acarologique représenté par la population de tiques potentiellement actives sur une unité d'observation, (ii) estimer un risque à l'échelle d'une parcelle, à savoir comment répartir l'effort d'échantillonnage entre le nombre d'unités d'observation et le nombre d'échantillonnages successifs par unités d'observation. / The estimation of animal abundance is essential to understand population dynamics, species interactions and disease patterns in populations and to estimate the risk of pathogens transmission. Several sampling methods such as single counts, distance sampling, removal sampling or capture mark recapture could be used to estimate abundance. In this study, we are investigated the abundance of Ixodes ricinus ticks, which are involved in the transmission of many pathogens. Tick abundance is commonly estimated by the number of nymphs captured during a single observation (a cloth dragged on a given surface). In this case, analyses of abundance patterns assumes that the probability of detecting a tick, hence the sampling rate, remains constant across the observations. In practice, however, this assumption is often not satisfied as the sampling rate may fluctuate between observation plots. The variation of sampling rate is never taken into account in estimations of tick abundance. Using a removal sampling design (RS), (i) we showed that the sampling rate and the usual abundance indicator (based on a single drag observation per spot) were both influenced by environmental conditions ; (ii) we proposed a method to determine the abundance indicator the least influenced by sampling rate variations ; (iii) using a hierarchical Bayesian model, we estimated simultaneously the abundance and the sampling rate according the type of vegetation, and the time of sampling. The sampling rate varied between 33,9 % and 47,4 % for shrubs and 53,6 % and 66,7 % for dead leaves. In addition, we show that the RS model tends to Poisson iid model when the population size N0 tends to infinite. This result conduct to infinite estimations for N0. We show that (i) Bayesian estimators were divergent for vague prior ; (ii) β(a, b) prior for a > 2 on τ conduct to convergent estimators. Then, we proposed recommendations for prior choice for τ parameter to give good estimations of N0 or τ. We discuss the relevance of RS for ticks and the possible perspectives to (i) estimate the acarologic risk associated to all potential active ticks for given spot, (ii) estimate the risk at the larger scale, i.e. how to distribute the sampling effort between number of spot and number of consecutive sampling by spot.