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This dissertation describes methods of mitigating radio frequency interference (RFI) in the frequency range 10-100 MHz, developing and evaluating coherent methods with which RFI is subtracted from the afflicted data, nominally resulting in no distortion of the underlying signals. This approach is of interest in weak signal applications such as radio astronomy, where the signal of interest may have interference-to-noise ratio much less than one, and so can be easily distorted by other methods. Environmental noise in this band is strong and non-white, so a realistic noise model is developed, with which we characterize the performance of signal parameter estimation, a key component of the proposed algorithms. Two classes of methods are considered: "generic" parameter estimation/subtraction (PE/S) and a modulation-specific form known as demodulation-remodulation ("demod--remod") PE/S. It is demonstrated for RFI in the form of narrowband FM and Broadcast FM that generic PE/S has the problem of severely distorting underlying signals of interest and demod-remod PE/S is less prone to this problem. Demod-remod PE/S is also applied and evaluated for RFI in the form of Digital TV signals. In both cases, we compare the performance of the demod-remod PE/S with that of a traditional adaptive canceling method employing a reference antenna, and propose a hybrid method to further improve performance. A new metric for "toxicity" is defined and employed to determine the degree to which RFI mitigation damages the underlying signal of interest. / Ph. D.

The purpose of this dissertation was to design, develop and field test an Intelligent Tutoring System (ITS) which I have called Process Oriented Subtraction-Interface for Tutoring or POSIT. POSIT is an Intelligent Tutoring System, developed on a microcomputer, and based on Anderson's (1982, 1987) ACT* model of learning. Unlike the tutoring systems that were developed by Anderson and his colleagues (Anderson, Boyle & Reiser, 1985; Anderson & Reiser, 1985) which focused on the tutoring of students in the context of problem solving, this system focuses on the tutoring of a cognitive skill-subtraction of whole-numbers. Because ACT* theory explicitly describes the interaction of declarative and procedural knowledge (procedural knowledge is dependent on declarative knowledge), this learning theory is ideally suited to the learning of a specific procedure. Further, other "intelligent" systems which have been applied to subtraction (Brown & Burton, 1978; Ohlsson & Langley, 1985; Young & O’Shea, 1981) tend to focus on the answers to subtraction exercises (product oriented). POSIT, on the other hand, is an interactive system that determines errors made by the child as the child attempts to solve subtraction problems. Another difference with previous systems is that POSIT has a teaching component. Other systems assume that instruction has been given at some other point in time prior to the use of the system. One final difference between POSIT and other systems is that it was developed with consideration of the diverse student population that is found in schools. Design decisions were based on the cognitive needs of low-, average- and high-achieving students. Such notions as reading level and complexity of the task were considered with regard to low achieving students. POSIT's ability to allow for a wide variety of algorithms was a consideration with regard to high achieving students and would also benefit students from all levels. The results of the field test of POSIT indicate that the error model used by POSIT was very successful (76% accurate, with potential to improve to between 80 to 90%). In addition, students appear to learn from the system as measured both on the system as well as on a paper and pencil transfer test. / Ed. D.

Studiens syfte är att undersöka sju lärares val av undervisningsmaterial vid introduktionen av subtraktion. Utgångspunkten i studien är taget ur livsvärldsfenomenologin, och data har samlats in genom semistrukturerade intervjuer där det kvalitativa datamaterialet sedan analyserats genom olika teman. Resultatet visar att samtliga lärare var överens om att konkret och laborativt material var att föredra vid introduktionen av subtraktion. Läroböckerna användes istället vid ett senare stadium för att hjälpa eleverna att befästa kunskaperna på en mer abstrakt nivå. / The aim of this study is to look into what teaching material seven teachers choose to use during the introduction of subtraction.The study has been inspired by life-world phenomenology, and has been conducted through semi-structured interviews, where the qualitative datasets later have been analyzed through different themes. The results show that all of the teachers agreed that concrete and laboratory materials where to prefer when introducing subtraction. The textbooks were used at a later stage to help the pupils consolidate their knowledge at a more abstract level.

Under den verksamhetsförlagda tiden väcktes intresset för huvudräkning hos mig, ef­tersom eleverna valde att använda sig av miniräknare trots att de hade kunskap om olika huvudräk­ningsstrategier. Enligt skolverket (2011b) skall eleverna vid huvudräkning ta del av olika strategier för att stärka självsäkerheten och tilltron till sin förmåga. Syftet med studien var att undersöka vilken eller vilka strategier som några elever i grundskolan föredrog vid huvudräk­ning inom addition och subtraktion. Undersökningen byggde på en kvalitativ metod och her­meneutiken som teoretisk forskningsansats. Urvalet bestod av ett målinriktat urval kombinerat med ett bekvämlighetsurval och resulterade i tre elever från vardera tre olika skolor och skol­områden. Huvudräkningsuppgifter samt intervjuer användes som datainsamlingsmetod. Data­bearbetningen av intervjuerna har utförts under inspiration av hermeneutiken som bygger på tolkningar. Resultatet av studien visade att inom addition är det strategin talsorter var för sig, algoritm och dubbla som elever föredrar helst. Inom subtraktion varierade eleverna mer vid valet av huvudräkningsstrategier, där de helst föredrar räkna uppåt, algoritm, jämföra, tals­orter var för sig, komplettera, lägga till och räkna neråt. Resultatet visade även att skillnaden mellan skolorna inte var så stor, dock fanns det en liten skillnad mellan skola II och skola III vad gäller strategin räkna uppåt. Skillnaden var att skola II föredrar flera olika strategier av­seende subtraktion. Det framgår tydligt att eleverna har en god kunskap om olika huvudräk­ningsstrategier vid addition och subtraktion. Enligt eleverna är det på grund av att lärarna i sin undervisning hade gått igenom olika strategier inom huvudräkning. / During my practical training periods I became interested in mental arithmetic because I expe­rienced that the students chose calculators despite their knowledge of mental arithmetic strat­egies. According to skolverket (2011b) students shall take part of different strategies to strengthen their selfconfidence and belief in their own ability. The purpose of this study was to identify which strategies some students in middle school choose when they are practising mental arithmetic in addition and subtraction. The study was based on a qualitative method and hermeneutic as a theoretical approach. The sample consisted of a targeted selection in combination with a convenience selection and resulted in three students from each of three different schools and school areas. Mental arithmetic tasks and interviews were used as data collection method. Data processing of the interviews has been processed using hermeneutics method and is based on interpretation. The result of the study showed that partitioning num­bers, algorithm and double was the most common mental arithmetic strategies in addition. When it comes to strategies in subtraction the students varied more and the most common was counting upwards, algorithm, compare, partitioning numbers, complementary addition and counting back from. The result also showed that there was no significant difference between the schools except school II and III when it comes to the strategy counting upwards. The dif­ference was that school II uses several different strategies when performing subtractions. It was rather clear that the students in this study had a good knowledge of various mental arithmetic strategies for addition and subtraction, and according to themselves it was a consequence of the various strategies in mental arithmetics, that their teachers had taught them.

Astronomical data sets are growing ever larger, and the area of high contrast imaging of exoplanets is no exception. With the advent of fast, low-noise detectors operating at 10 to 1000 Hz, huge numbers of images can be taken during a single hours-long observation. High frame rates offer several advantages, such as improved registration, frame selection, and improved speckle calibration. However, advanced image processing algorithms are computationally challenging to apply. Here we describe a parallelized, cloud-based data reduction system developed for the Magellan Adaptive Optics VisAO camera, which is capable of rapidly exploring tens of thousands of parameter sets affecting the Karhunen-Loeve image processing (KLIP) algorithm to produce high-quality direct images of exoplanets. We demonstrate these capabilities with a visible-wavelength high contrast data set of a hydrogen-accreting brown dwarf companion.

Human fingerprints are rich in details called the minutiae, which can be used as identification marks for fingerprint verification. To get the details, the fingerprint capturing techniques are to be improved. Since when we the fingerprint is captured, the noise from outside adds to it. The goal of this thesis is to remove the noise present in the fingerprint image. To achieve a good quality fingerprint image, this noise has to be removed or suppressed and here it is done by using an algorithm or technique called ’Spectral Subtraction’, where the algorithm is based on subtraction of estimated noise spectrum from noisy signal spectrum. The performance of the algorithm is assessed by comparing the original fingerprint image and image obtained after spectral subtraction several parameters like PSNR, SSIM and also for different fingerprints on the database. Finally, performance matching was done using NIST matching software, and the obtained results were presented in the form of Receiver Operating Characteristics (ROC)graphs, using MATLAB, and the experimental results were presented.

The problem of the study is the delineation and subsequent application of a system of theoretical concepts associated with teaching addition, subtraction, multiplication, and division of whole numbers--referred to as the "operations of arithmetic."

This diploma thesis deals with third-graders from one of Prague's elementary schools and their understanding of numbers. In addition to the Prodos textbooks, some didactical ideas were taken from the Fraus textbooks, which are aimed at the development of children's understanding mathematics. The experiments were carried out in a classroom and lasted one and a half year. Seven pupils were chosen to take part. The experiments were aimed at gauging their semantic and structural understanding of numbers. The pupils worked individually and were individually interviewed after the experiments. The assumption that pupils use strategies that are not taught in the classroom was confirmed, as well as the fact that the operation of subtraction is much more complicated than addition in mental arithmetic and also in written counting. However, the assumption that the pupils perform better when faced with financial matters as opposed to other situations was not confirmed. It came to light that when creating a verbal task, it is necessary to consider the pupil's understanding of the vocabulary used. Key Words: addition, subtraction, decomposition of number, computation, mathematics, calculative strategies

L’analyse vidéo pour la vidéo-surveillance nécessite d’avoir une bonne résolution pour pouvoir analyser les flux vidéo avec un maximum de robustesse. Dans le contexte de la détection d’objets stationnaires dans les grandes zones, telles que les parkings, le compromis entre la largeur du champ d’observation et la bonne résolution est difficile avec un nombre limité de caméras. Nous allons utiliser une paire de caméras à focale variable de type Pan-Tilt-Zoom (PTZ). Les caméras parcourent un ensemble de positions (pan, tilt, zoom) prédéfinies afin de couvrir l’ensemble de la scène à une résolution adaptée. Chacune de ces positions peut être vue comme une caméra stationnaire à très faible taux de rafraîchissement. Dans un premier temps notre approche considère les positions des PTZ comme des caméras indépendantes. Une soustraction de fond robuste aux changements de luminosité reposant sur une grille de descripteurs SURF est effectuée pour séparer le fond du premier plan. La détection des objets stationnaires est effectuée par ré-identification des descripteurs à un modèle du premier plan. Dans un deuxième temps afin de filtrer certaines fausses alarmes et pouvoir localiser les objets en 3D une phase de mise en correspondance des silhouettes entre les deux caméras et effectuée. Les silhouettes des objets stationnaires sont placées dans un repère commun aux deux caméras en coordonnées rectifiées. Afin de pouvoir gérer les erreurs de segmentation, des groupes de silhouettes s’expliquant mutuellement et provenant des deux caméras sont alors formés. Chacun de ces groupes (le plus souvent constitué d’une silhouette de chaque caméra, mais parfois plus) correspond à un objet stationnaire. La triangulation des points frontière haut et bas permet ensuite d’accéder à sa localisation 3D et à sa taille. / Video analysis for video surveillance needs a good resolution in order to analyse video streams with a maximum of robustness. In the context of stationary object detection in wide areas a good compromise between a limited number of cameras and a high coverage of the area is hard to achieve. Here we use a pair of Pan-Tilt-Zoom (PTZ) cameras whose parameter (pan, tilt and zoom) can change. The cameras go through a predefined set of parameters chosen such that the entire scene is covered at an adapted resolution. For each triplet of parameters a camera can be assimilated to a stationary camera with a very low frame-rate and is referred to as a view. First each view is considered independently. A background subtraction algorithm, robust to changes in illumination and based on a grid of SURF descriptors, is proposed in order to separate background from foreground. Then the detection and segmentation of stationary objects is done by reidentifying foreground descriptor to a foreground model. Then in order to filter out false alarms and to localise the objects in the3D world, the detected stationary silhouettes are matched between the two cameras. To remain robust to segmentation errors, instead of matched a silhouette to another, groups of silhouettes from the two cameras and mutually explaining each other are matched. Each of the groups then correspond to a stationary object. Finally the triangulation of the top and bottom points of the silhouettes gives an estimation of the position and size of the object.