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Universities and colleges are embracing and utilizing technology to a rapidly increasing extent, responding to its cost-effectiveness and efficiency as well as the regularity with which 21st century students rely upon it in their everyday lives. Chief amongst the technology used in higher education are Learning Management Systems (LMS), such as Blackboard, Sakai, and CANVAS. Urban community colleges have also embraced LMS, but with student bodies that often lack regular access to or extensive experience with using technology for socio-economic or generational reasons, the outcomes from using LMS can be very different to those experienced at four-year institutions that generally serve a more affluent, traditionally-aged demographic. In particular, students in developmental courses, or those courses designed for individuals who could not test into college-level courses, can be particularly challenged when it comes to using LMS in their studies as it is an additional component to which they must acculturate in higher education whilst attempting to rectify their skills deficiencies. For faculty teaching developmental students, this can raise the question of whether it is important to acclimate students to the technology they will be called upon to use in the 21st century classroom or whether the sole focus should be remediating students’ lacking academic skills. This qualitative, interpretivist, constructivist-activist/pragmatic study uses interviews with urban community college professors who use or reject the college’s LMS (i.e. CANVAS) to varying extents in their classrooms, non-participant observations of the course components those professors who use CANVAS post online, and course artifacts to examine and reflect upon professors’ experiences with employing or eschewing such technology with their students. / Urban Education

The least mean square (LMS) algorithm is widely expected to operate near the corresponding Wiener filter solution. An exception to this popular perception occurs when the algorithm is used to adapt a transversal equalizer in the presence of additive narrowband interference. The steady-state LMS equalizer behavior does not correspond to that of the fixed Wiener equalizer: the mean of its weights is different from the Wiener weights, and its mean squared error (MSE) performance may be significantly better than the Wiener performance. The contributions of this study serve to better understand this so-called non-Wiener phenomenon of the LMS and normalized LMS adaptive transversal equalizers. The first contribution is the analysis of the mean of the LMS weights in steady state, assuming a large interference-to-signal ratio (ISR). The analysis is based on the Butterweck expansion of the weight update equation. The equalization problem is transformed to an equivalent interference estimation problem to make the analysis of the Butterweck expansion tractable. The analytical results are valid for all step-sizes. Simulation results are included to support the analytical results and show that the analytical results predict the simulation results very well, over a wide range of ISR. The second contribution is the new MSE estimator based on the expression for the mean of the LMS equalizer weight vector. The new estimator shows vast improvement over the Reuter-Zeidler MSE estimator. For the development of the new MSE estimator, the transfer function approximation of the LMS algorithm is generalized for the steady-state analysis of the LMS algorithm. This generalization also revealed the cause of the breakdown of the MSE estimators when the interference is not strong, as the assumption that the variation of the weight vector around its mean is small relative to the mean of the weight vector itself. Both the expression for the mean of the weight vector and for the MSE estimator are analyzed for the LMS algorithm at first. The results are then extended to the normalized LMS algorithm by the simple means of adaptation step-size redefinition. / Ph. D.

Extensive disturbance rejection methods have been established for time-invariant systems. However, the development of these techniques has not focused on application to time-periodic systems in particular until recently. The filtered-X LMS algorithm is regarded as the best disturbance rejection technique for aperiodic systems by many, as has been proven in the acoustics industry for rejecting unwanted noise. Since this is essentially a feedforward approach, we might expect its performance to be good with respect to time-periodic systems in which the disturbance frequency is already known. The work presented in this thesis is an investigation of the performance of the filtered-X LMS algorithm for disturbance rejection in time-periodic systems. Two cases are examined: a generalized linear, time-periodic system and the helicopter rotor blade in forward flight. Results for the generalized system show that the filtered-X LMS algorithm does converge for time-periodic disturbance inputs and can produce very small errors. For the helicopter rotor blade system the algorithm is shown to produce very small errors, with a 96%, or 14 dB, reduction in error from the open-loop system. The filtered-X LMS disturbance rejection technique is shown to provide a successful means of rejecting timeperiodic disturbances for time-periodic systems. / Master of Science

Porttelefoner används ofta i högljudda miljöer. Ett exempel på en sådan miljö är vindutsatta områden, där operatören i ett rum kan uppleva svårigheter att uppfatta tal från användaren som talar i en porttelefon på grund av den omgivande höga ljudnivån. Många porttelefoner och andra liknande enheter stöter vanligtvis på utmaningar och begränsningar, särskilt när det gäller snabbhet, storlek, resurshantering och hantering av dynamiska signaler.  Detta projekt genomfördes vid ett svenskt företag inom nätverksbaserade lösningar för videoövervakning och fysisk säkerhet. Projektet syftar till att utforska och implementera ett adaptiv filter med en adaptiv algoritm i C-programmering för att komplettera ett digitalt signalbehandlingssystem som en strategi för att förbättra ljudkvaliteten genom att reducera bruset hos porttelefoner i utmanande miljöer. Genom att tillämpa ett lämpligt adaptiv filter i en Raspberry Pi för att simulera en porttelefon, strävar projektet efter att reducera brus och optimera talet. Några av de vanligaste filtreringsalgoritmerna som använts i tidigare forskning för att förbättra ljudkvaliteten är Least mean square, Normalized least mean square och Recursive least square som även utvärderas i denna studie. Efter noggranna studier valdes algoritmen Normalized least mean square för implementering i detta projekt. Algoritmens prestanda utvärderas med hjälp av beräkningstiden, medelkvadratfelet och signal-till-brus-förhållandet i Matlab samt användartester för att säkerställa kvaliteten. Detta projekt uppnådde målen genom att utveckla ett fungerande adaptivt filter. Det rekommenderas att implementera filtret i en porttelefon där mikrofonerna inte är placerade nära varandra för att förhindra upptagning av dubbla liknande signaler. Under projektets gång hanterade systemet kontinuerligt dataströmmar effektivt i praktiska tester, vilket bekräftade att det fungerade utan fördröjningar. Detta bevisade det adaptiva filtrets effektivitet i verkliga applikationer, särskilt i högljudda miljöer. / Intercoms are often used in noisy environments. An example of such an environment is windy areas, where the operator inside a room may find it difficult to perceive speech from a user speaking through an intercom due to the surrounding high noise levels. Many intercoms and other similar devices typically encounter challenges and limitations, especially in terms of speed, size, resource management, and handling of dynamic signals. This project was carried out at a Swedish company specializing in network-based solutions for video surveillance and physical security. The project’s objective was to study and implement an adaptive filter with an adaptive algorithm in C programming to complement a digital signal processing system, as a strategy to enhance sound quality by reducing noise in intercoms in challenging environments. By applying a suitable adaptive filter in a Raspberry Pi to simulate an intercom, the goal of the project is to reduce noise and optimize speech clarity. Some of the most common filtering algorithms used in previous research to improve sound quality include Least mean square, Normalized least mean square och Recursive least square, which are evaluated in this study. After thorough studies, the Normalized least mean square algorithm was selected for implementation in this project. The performance of the algorithm is assessed using computation time, mean squared error, and signal-to-noise ratio in Matlab, along with user testing to ensure quality. This project achieved its goals by developing a functional adaptive filter. It is recommended to implement the filter in an intercom where the microphones are not placed close to each other to prevent the capture of similar duplicate signals. Throughout the project, the system continuously handled data streams effectively in practical tests, confirming that it operated without delays. This demonstrated the adaptive filter's effectiveness in real applications, particularly in noisy environments.

Une image hyperspectrale est un cube de données 3D dont chaque pixel fournit des informations spectrales locales sur un grand nombre de bandes contiguës sur une scène d'intérêt. Les images observées peuvent subir une dégradation due à l'instrument de mesure, avec pour conséquence l'apparition d'un flou sur les images qui se modélise par une opération de convolution. La déconvolution d'image hyperspectrale (HID) consiste à enlever le flou pour améliorer au mieux la résolution spatiale des images. Un critère de HID du type Tikhonov avec contrainte de non-négativité est proposé dans la thèse de Simon Henrot. Cette méthode considère les termes de régularisations spatiale et spectrale dont la force est contrôlée par deux paramètres de régularisation. La première partie de cette thèse propose le critère de courbure maximale MCC et le critère de distance minimum MDC pour estimer automatiquement ces paramètres de régularisation en formulant le problème de déconvolution comme un problème d'optimisation multi-objectif. La seconde partie de cette thèse propose l'algorithme de LMS avec un bloc lisant régularisé (SBR-LMS) pour la déconvolution en ligne des images hyperspectrales fournies par les systèmes de whiskbroom et pushbroom. L'algorithme proposé prend en compte la non-causalité du noyau de convolution et inclut des termes de régularisation non quadratiques tout en maintenant une complexité linéaire compatible avec le traitement en temps réel dans les applications industrielles. La troisième partie de cette thèse propose des méthodes de séparation-déconvolution conjointes basés sur le critère de Tikhonov en contextes hors-ligne ou en-ligne. L'ajout d'une contrainte de non-négativité permet d’améliorer leurs performances / A hyperspectral image is a 3D data cube in which every pixel provides local spectral information about a scene of interest across a large number of contiguous bands. The observed images may suffer from degradation due to the measuring device, resulting in a convolution or blurring of the images. Hyperspectral image deconvolution (HID) consists in removing the blurring to improve the spatial resolution of images at best. A Tikhonov-like HID criterion with non-negativity constraint is considered here. This method considers separable spatial and spectral regularization terms whose strength are controlled by two regularization parameters. First part of this thesis proposes the maximum curvature criterion MCC and the minimum distance criterion MDC to automatically estimate these regularization parameters by formulating the deconvolution problem as a multi-objective optimization problem. The second part of this thesis proposes the sliding block regularized (SBR-LMS) algorithm for the online deconvolution of hypserspectral images as provided by whiskbroom and pushbroom scanning systems. The proposed algorithm accounts for the convolution kernel non-causality and including non-quadratic regularization terms while maintaining a linear complexity compatible with real-time processing in industrial applications. The third part of this thesis proposes joint unmixing-deconvolution methods based on the Tikhonov criterion in both offline and online contexts. The non-negativity constraint is added to improve their performances

In this thesis, the design and implementation of a Portable Feedback Active Noise Controller Headphone System, which is based on Texas Instruments TMS320VC5416PGE120 Fixed Point DSP, is described. Problems resulted from fixed-point implementation of LMS algorithm and delays existing in digital ANC implementation are determined. Effective solutions to overcome the aforementioned problems are proposed based on the literature survey. Design of the DSP based control card is explained and crucial points about analog-digital-mixed board design for noise sensitive applications are explained. Filtered input LMS algorithm, filtered input normalized LMS algorithm and filtered input sign-sign LMS algorithm are implemented as adaptation algorithms. The advantages and disadvantages of using modified LMS algorithms are indicated. The selection of the parameters of these algorithms is based on theoretical results and experiments. The real time performances of different adaptation algorithms are compared with each other as well as with a commercial analog ANC headphone under different types of artificial and natural noise signals. Moreover, practical conditions such as put on - put off case and dynamic range overflow case are handled with additional software implementations. It is shown that adaptive ANC systems improve the noise reduction significantly when the noise is within a narrow frequency range and this reduction can be applied to a wider frequency range. It is also shown that the problems of digitally implemented adaptive filters which are based on tracking capability, stability, dynamic range and portability can be fixed to challenge with the analog commercial ANC systems.

The aim of this study was to describe and analyse online teaching practices in the Swedish higher education context. The study had an online ethnographic approach and was based on empirical data on the teaching in two university courses. The study rested primarily on observational data but interviews and available documents also formed the basis for analysis. Empirical data were analysed with a perspective of practice theory – a perspective within a sociomaterial account. The results showed that online teaching was characterised by an embodied sociomaterial practice. The teacher’s body could be understood as both multiple and closely interwoven with technology. Furthermore, the teacher’s body was used in the teaching situation to reduce technological complexity but also, along with other forms of materiality, to prefigure what kind of teaching would take place. Teacher interventions in online environments could furthermore be understood as relational to both technology (that is the virtual material arrangement) and teachers’ doings and sayings (that is the teaching practice). Teacher interventions were aimed at making the arrangement intelligible for the students. The study showed that teacher interventions arranged both students and information and communication technology (ICT) in order to make them work as a teaching practice. The teaching practice that emerged was characterised as an interplay between virtual materiality and social practice, where asymmetricrelations between teachers and the ICT prevailed. / Syftet med föreliggande studie var att beskriva och analysera undervisningspraktiker online i svensk högre utbildningskontext. Studien har en onlineetnografisk ansats och baseras på empiriska data av undervisningen i två kurser på universitetsnivå. Studien stödjer sig främst på observationsdata men även intervjuer och dokumentstudier ligger som grund för analysen. Empiriska data har analyserats med ett praktikteoretiskt perspektiv – ett perspektiv inom sociomateriell teoribildning. Resultatet visar att undervisning online kännetecknas av en förkroppsligad sociomateriell praktik. Lärarkroppen kan förstås som både multipel och tätt sammanvävd med teknologi. Vidare används lärarkroppen i undervisningssituationen för att reducera komplexitet men även för att, tillsammans med annan materialitet, prefigurera vad det är för typ av undervisning som kommer att utspela sig. Vidare kan lärarinterventioner i onlinemiljöer förstås som relationella till både tekniken (det vill säga det virtuellt materiella arrangemanget) och lärares göranden och säganden (det vill säga undervisningspraktiken). Lärarinterventioner syftar till att göra arrangemanget begripligt för studenterna. Studien visar att lärarinterventionerna arrangerar både studenter och informations- och kommunikationsteknologi (IKT) i syfte att få dem att fungera som en undervisningspraktik. Den undervisningspraktik som uppstår är inte given på förhand utan emergent. Den karaktäriseras av ett samspel mellan virtuell materialitet och social praktik där asymmetriska relationer mellan lärare och IKT råder.

Made available in DSpace on 2016-08-17T14:52:41Z (GMT). No. of bitstreams: 1 Dissertacao-WilanderTestonePereiraSilva.pdf: 3903191 bytes, checksum: b91ff906a27937df64d75b330c6ea137 (MD5) Previous issue date: 2016-03-11 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this dissertation we present a research in aspects of stochastic modeling, convergence and applications of least mean square (LMS) algorithm, normalized least mean square (NLMS) algorithm and proportionate normalized least mean square (PNLMS) algorithm. Specifically, the aim is to address the LMS algorithm in your extension, defining his concepts, demonstrations of properties, algorithms and analysis of convergence, Learning Curve and Misadjustment of the algorithm in question. Within of the context of sensor networks and spatial filtering is evaluated the performance of the algorithms by the learning curve of the referred algorithms for arrangements of adaptive antennas. In the intrinsic context of the application in electrical engineering, in area of telecommunications that seek the best alternative and aims to optimize the process of transmission/reception to eliminate interference, and the least amount of elements in adaptive antenna arrays, which they are known as smart antenna, which aims to reach a signal noise ratio for small value, with appropriate number of elements. The performance of the LMS algorithm is evaluated in sensor networks that is characterized by an antenna array. Results of computer simulations for different scenarios of operation show that the algorithms have good numerical results of convergence to a suitable choice of the parameters related with the rate of learning that are associated with their average curves and the beamforming of the smart antenna array. / Nesta dissertação de mestrado apresenta-se uma investigação em aspectos de modelagem estocástica, convergência e aplicações dos algoritmos de mínimos quadrados médio (LMS), mínimos quadrados médio normalizado (NLMS) e mínimos quadrados médio normalizado proporcional (PNLMS). Particularmente, aborda-se o Algoritmo LMS em sua extensão, definindo conceitos, demonstrações de propriedades, algoritmos e análise de convergência, Curva de Aprendizagem e Desajuste do referido algoritmo. Dentro do contexto de redes de sensores e filtragem espacial avalia-se o desempenho dos algoritmos por meio da curva de aprendizagem dos referidos algoritmos para os arranjos de antenas adaptativas. No contexto intrínseco da aplicação em engenharia elétrica, isto é, na área de telecomunicações procura-se a melhor alternativa e almeja-se a otimização do processo de transmissão/recepção para eliminar interferências e a menor quantidade de elementos em arranjos de antenas adaptativas, que são conhecidas como antenas inteligentes, e que tem como objetivo atingir uma relação Sinal Ruído para valor pequeno, com número adequado de elementos. O desempenho do algoritmo LMS é avaliado em redes de sensores que é caracterizada por um arranjo de antenas. Resultados de simulações computacionais para diferentes cenários de operação mostram que os algoritmos apresentam bons resultados numéricos de convergência para uma escolha adequada dos parâmetros relacionados com a taxa de aprendizagem que são associadas com suas curvas médias e com a conformação de feixes do arranjo em antenas inteligentes.

This work deals with digital signal processing in the field of adaptive filtering. Fundamental basics of adaptive filtering are described and primary aim is to create executable laboratory examples, using adaptive filtering, in LabView programming language. These laboratory examples are intended to be used by students fo studying and during laboratory lessons. Objective is to connect the examples with external devices, such as microphone. A microphone is used as an user's speech input acquiring interface. In the thesis is depicted Wiener's filter and problem of adaptive filtering is discussed. Contemporary adaptive algorithms are described and their applications as well. Most mentioned is the LMS algorithm and it's forms. Laboratory examples use following concepts: Adaptive Echo Cancellation, Active Noise Control and System Identification. Each of these examples is solely executable (need for LabView or Run-time engine), consisting also of theory with diagrams. Examples therefore are usable even without manual.