Ces travaux de thèse visent à valoriser la lignine, biopolymère aromatique le plus abondant sur terre. Pour cela, la dépolymérisation oxydante de la lignine par voie enzymatique a été explorée afin d’obtenir des synthons aromatiques fonctionnalisés. La laccase et le système laccase médiateur (LMS) ont été sélectionnés comme système enzymatique. Dans une première partie, les paramètres réactionnels (choix du médiateurs, température, co-solvant…) de fonctionnement optimal du LMS ont été déterminés notamment via l’utilisation de molécules modèles de lignine. Ces conditions optimales ont été directement appliquées pour l’oxydation d’une lignine organosolv issue d’une plante herbacée. Une étape de fractionnement organique a été conduite sur la lignine avant oxydation afin d’éliminer les populations à l’origine de réactions de couplage. La lignine a ensuite été oxydée par le LMS en milieu biphasique, puis traitée au peroxyde d’hydrogène. Ce procédé en trois étapes a permis de générer des composés aromatiques monomères à trimères (mis en évidence par chromatographies SEC, HPLC, GC et LC-MS) et a été appliqué avec succès à une seconde lignine issue de conifère. Dans les deux cas, des rendements élevés ont été constatés comparés à ceux obtenus dans la littérature. Après isolation, les composés aromatiques produits pourraient trouver des applications comme précurseurs dans les industries de la chimie fine et des polymères. / This work aims at valorizing lignin, the most abundant aromatic biopolymer on earth. For that purpose, an enzymatic approach for the oxidative depolymerization of lignin was investigated in order to obtain fine chemicals. Laccase and the laccase-mediator system (LMS) were selected for the enzymatic oxidation. In the first part, optimal conditions (type of mediator, temperature, co-solvent…) were determined especially by studying reactions on lignin model molecules. These conditions were applied for the oxidation of an organosolv grass lignin. Prior to the oxidation, an organic fractionation was conducted on the lignin in order to remove the population responsible for radical coupling. Then, the lignin was oxidized by the LMS in a biphasic medium followed by a mild hydrogen peroxide treatment. This three-step process allowed the production of monomeric to trimeric aromatic compounds (as shown by SEC, HPLC, GC and LC-MS) and was successfully applied to a different organosolv lignin coming from hardwood. High yield were obtained in both cases as compared with literature results. After isolation, the obtained aromatic molecules could be of interest as precursors for the fine chemistry and polymer industries.

This thesis deals with the creation of an electronic course, designation of a reliable support system for testing and also with the preparation and suggestion of testing questions for a Computer hardware subject. Another part of the thesis is the appending Graphical User Interface (GUI) for generation of questions of type “Cloze”. It means “Embedded answer” in Moodle. Nonetheless, the significant part of the thesis is the designation of its own E-learning information system. This system enables the students to have the opportunity to educate themselves and also to get prepared for the successful completion by passing the electronic exam.

<p>Dagens utveckling inom distansutbildning har lett till att det blir allt viktigare att välja en lärplattform som är anpassat till företagets eller organisationens verksamhet. Nya effektiva utbildningsmetoder som komplement till den traditionella utbildningen möjliggörs av den nya tekniken där e-learning har en framträdande roll. E-learning gör att lärandet inte längre är beroende av ett fysiskt klassrum och en specifik tidpunkt utan utbildningen blir mer flexibel, interaktiv samt fokuserar mer på själva på lärandet.</p><p>Syftet med denna uppsats har varit att kartlägga hur ett LMS bör vara utformat vad det gäller design, funktion och användbarhetsfaktorer för att underlätta val av lärplattform (LMS). Studien har visat att det designmässigt är lämpligt att följa vedertagna författares riktlinjer – oavsett om det gäller LMS eller design av en funktion i ett LMS. När det handlar om användbarhetsfaktorer har studien visat att vissa val av funktioner kan vara avgörande.</p><p>De slutsatser som framkommit i vår studie är att en organisation eller ett företag bör välja ett LMS som är utbyggbart. Efterhand som företaget eller organisationen utvecklas inom sitt LMS, efterfrågas fler funktioner och möjligheter. Det har visat sig att LMS som följer en internationell standard, SCORM – vilket möjliggör återanvändning av material samt överföring mellan olika LMS, är att föredra. </p><p>Vidare visade studien att framtidens LMS måste anpassas till kommande behov både vad det gäller möjligheter för den enskilde användaren att göra personliga inställningar samt att kunna kommunicera via exempelvis chat, forum, e-post, webbkamera eller liknande. Vidare måste fokus ligga på att främja lärandet, att välja ett LMS med potential att växa och personalisera tror vi främjar lärandet i positiv riktning.</p>

Dagens utveckling inom distansutbildning har lett till att det blir allt viktigare att välja en lärplattform som är anpassat till företagets eller organisationens verksamhet. Nya effektiva utbildningsmetoder som komplement till den traditionella utbildningen möjliggörs av den nya tekniken där e-learning har en framträdande roll. E-learning gör att lärandet inte längre är beroende av ett fysiskt klassrum och en specifik tidpunkt utan utbildningen blir mer flexibel, interaktiv samt fokuserar mer på själva på lärandet. Syftet med denna uppsats har varit att kartlägga hur ett LMS bör vara utformat vad det gäller design, funktion och användbarhetsfaktorer för att underlätta val av lärplattform (LMS). Studien har visat att det designmässigt är lämpligt att följa vedertagna författares riktlinjer – oavsett om det gäller LMS eller design av en funktion i ett LMS. När det handlar om användbarhetsfaktorer har studien visat att vissa val av funktioner kan vara avgörande. De slutsatser som framkommit i vår studie är att en organisation eller ett företag bör välja ett LMS som är utbyggbart. Efterhand som företaget eller organisationen utvecklas inom sitt LMS, efterfrågas fler funktioner och möjligheter. Det har visat sig att LMS som följer en internationell standard, SCORM – vilket möjliggör återanvändning av material samt överföring mellan olika LMS, är att föredra. Vidare visade studien att framtidens LMS måste anpassas till kommande behov både vad det gäller möjligheter för den enskilde användaren att göra personliga inställningar samt att kunna kommunicera via exempelvis chat, forum, e-post, webbkamera eller liknande. Vidare måste fokus ligga på att främja lärandet, att välja ett LMS med potential att växa och personalisera tror vi främjar lärandet i positiv riktning.

The well-known code division multiple access (CDMA) decorrelating detector (DD) and minimum mean-square error (MMSE) detector use a bank of correlators, followed by the inverse of the matrix operation to eliminate the multiple access interference (MAI). However, the operation for the inverse of the matrix involves a great deal of computation, especially when the users¡¦ number is large. Therefore, in this thesis, we propose some recursive methods, the least-mean-square (LMS) algorithm and the recursive least-squares (RLS) algorithm, to detect users¡¦ signals adaptively. We make use of the analogy between a traditional Winner filter and the decorrelating detector to construct adaptive implementation schemes of the decorrelating detector and MMSE detector, called decorrelating transversal filter and MMSE transversal filter, respectively. We applied both LMS algorithm and RLS algorithm to the decorrelating transversal filter and MMSE transversal filter, just as the ways to apply the LMS algorithm and RLS algorithm to the Winner filters. With the proposed schemes, we can greatly reduce the computational complexity of a CDMA multi-user detector while maintaining an acceptable performance.

No description available.

This master thesis has been performed at SAAB AB in Järfälla, Sweden.A radar warning receiver must alert the user when someone highlights it with radarsignals. Radar signals used today varies and has a wide frequency band. In order todetect all possible radar signals the radar warning receiver must have a widebandwidth. This results in that the noise power will be high in the radar warningreceiver and weak radar signals will be hard to detect or even undetected.The aim of the thesis work was to investigate the possibility to suppress the noise inthe received radar signals. Unfortunately we do not know the frequency of thereceived radar signals, since the frequency has been decided by the threat radar. Wehave used adaptive filters, which adapts it band-pass to the received radar signal. Theadaptive filters must converge quickly to the state it reduces the noise and passes theradar signals since radar pulses can be very short in the time domain. We also wantto achieve a high SNR gain that is a measurement of how well the adaptive filterreduces the noise.We have investigated two adaptive algorithms, the recursive least square (RLS)algorithm and the least mean square (LMS) algorithm. We found out that the LMSalgorithm was more suitable for noise cancellation in radar applications due to its lowcomplexity and stability compared to RLS algorithm. The LMS algorithm gave SNRgains in the span 14-20 dB for different radar pulses.

abstract: The growing use of Learning Management Systems (LMS) in classrooms has enabled a great amount of data to be collected about the study behavior of students. Previously, research has been conducted to interpret the collected LMS usage data in order to find the most effective study habits for students. Professors can then use the interpretations to predict which students will perform well and which student will perform poorly in the rest of the course, allowing the professor to better provide assistance to students in need. However, these research attempts have largely analyzed metrics that are specific to certain graphical interfaces, ways of answering questions, or specific pages on an LMS. As a result, the analysis is only relevant to classrooms that use the specific LMS being analyzed. For this thesis, behavior metrics obtained by the Organic Practice Environment (OPE) LMS at Arizona State University were compared to student performance in Dr. Ian Gould’s Organic Chemistry I course. Each metric gathered was generic enough to be potentially used by any LMS, allowing the results to be relevant to a larger amount of classrooms. By using a combination of bivariate correlation analysis, group mean comparisons, linear regression model generation, and outlier analysis, the metrics that correlate best to exam performance were identified. The results indicate that the total usage of the LMS, amount of cramming done before exams, correctness of the responses submitted, and duration of the responses submitted all demonstrate a strong correlation with exam scores. / Dissertation/Thesis / Masters Thesis Computer Science 2015

Laser Measurement Systems (LMS) are used in autonomous agricultural vehicles for guidance and obstacle detection purposes. In the particular case of agricultural vehicles, the efficiency of LMS measurements is affected by mechanical vibrations induced by the operation of these machines on uneven terrains. The objective of this study was to evaluate the effectiveness of a mounting system capable of reducing the transmission of mechanical vibrations to an LMS sensor installed on an agricultural tractor for the purpose of improving the detection accuracy of obstacles during field operation. A stabilization system (SS) was designed for a SICK LMS 291-S14 scanner. The LMS sensor and the SS were installed on an agricultural tractor to scan four objects positioned at known locations in the field. An experimental analysis was carried out to evaluate the detection accuracy of the LMS sensor under different operating conditions: with and without SS; with and without support bars (S); and for different types of terrains (in terms of roughness) and field operating speed. The detection accuracy of the LMS sensor was assessed by determining the difference between the known location of the four objects and their corresponding estimated location from the LMS measurements. The increase of tractor speed had a negative effect on the accuracy of the LMS sensor with an increase in the positioning error of up to 75%. However, it was not possible to establish a clear relationship between terrain roughness and the accuracy of the LMS sensor. The addition of the S systems positively affected the accuracy of the LMS sensor and resulted in a 41% decrease of the average positioning error from 0.340 to 0.201 m. Finally, the used of the SS mounting system decreased the average positioning error by 57% from 0.382 to 0.161 m. These experimental results confirmed the effectiveness of the joint use of the SS and S mounting systems in improving the accuracy of the LMS sensor mounted on an agricultural tractor through a reduction in transmitted vibrations.

The analysis of this thesis concerns various problems associated with adaptive CDMA multi-user detection in asynchronous multi-path channels. Starting with some simple concept of Wiener filtering and correlating detector, we construct a novel adaptive decorrelating transversal filter suitable for CDMA multi-user detection in uplink channels. Then, we make use of the LMS and RLS algorithms to replace the traditional decorrelating transversal filter (which is also called inverse matrix based decorrelating detector) to make the scheme work fully adaptively. In this way, a great advantage in terms of computation load reduction is made possible. To further improve the detection efficiency, we will also make use of RAKE receiver to enhance the overall decision reliability in the proposed adaptive CDMA MUD scheme. Although the focus of this thesis is put on analysis, we will also use computer simulations to counter-check the results obtained from theoretical analysis, showing a very good match between the two. In the last part of the thesis, we will also discuss the various issues on fully blind implementation of the proposed adaptive CDMA MUD scheme with some useful multipath channel delay and amplitude estimation algorithms.