28 research outputs found

    Development of a satellite SAR image spectra and altimeter wave height data assimilation system for ERS-1

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    The applicability of ERS-1 wind and wave data for wave models was studied using the WAM third generation wave model and SEASAT altimeter, scatterometer and SAR data. A series of global wave hindcasts is made for the surface stress and surface wind fields by assimilation of scatterometer data for the full 96-day SEASAT and also for two wind field analyses for shorter periods by assimilation with the higher resolution ECMWF T63 model and by subjective analysis methods. It is found that wave models respond very sensitively to inconsistencies in wind field analyses and therefore provide a valuable data validation tool. Comparisons between SEASAT SAR image spectra and theoretical SAR spectra derived from the hindcast wave spectra by Monte Carlo simulations yield good overall agreement for 32 cases representing a wide variety of wave conditions. It is concluded that SAR wave imaging is sufficiently well understood to apply SAR image spectra with confidence for wave studies if supported by realistic wave models and theoretical computations of the strongly nonlinear mapping of the wave spectrum into the SAR image spectrum. A closed nonlinear integral expression for this spectral mapping relation is derived which avoids the inherent statistical errors of Monte Carlo computations and may prove to be more efficient numerically

    Generating Circuit Tests by Exploiting Designed Behavior

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    This thesis describes two programs for generating tests for digital circuits that exploit several kinds of expert knowledge not used by previous approaches. First, many test generation problems can be solved efficiently using operation relations, a novel representation of circuit behavior that connects internal component operations with directly executable circuit operations. Operation relations can be computed efficiently by searching traces of simulated circuit behavior. Second, experts write test programs rather than test vectors because programs are more readable and compact. Test programs can be constructed automatically by merging program fragments using expert-supplied goal-refinement rules and domain-independent planning techniques

    TransBooster:black box optimisation of machine translation systems

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    Machine Translation (MT) systems tend to underperform when faced with long, linguistically complex sentences. Rule-based systems often trade a broad but shallow linguistic coverage for a deep, fine-grained analysis since hand-crafting rules based on detailed linguistic analyses is time-consuming, error-prone and expensive. Most datadriven systems lack the necessary syntactic knowledge to effectively deal with non-local grammatical phenomena. Therefore, both rule-based and data-driven MT systems are better at handling short, simple sentences than linguistically complex ones. This thesis proposes a new and modular approach to help MT systems improve then output quality by reducing the number of complexities in the input. Instead of trying to reinvent the wheel by proposing yet another approach to MT, we build on the strengths of existing MT paradigms while trying to remedy their shortcomings as much as possible. We do this by developing TransBooster, a wrapper technology that reduces the complexity of the MT input by a recursive decomposition algorithm which produces simple input chunks that are spoon-fed to a baseline MT system TransBooster is not an MT system itself: it does not perform automatic translation, but operates on top of an existing MT system, gulding it through the input and trying to help the baseline system to improve the quality of its own translations through automatic complexity reduction. In this dissertation, we outline the motivation behind TransBooster, explain its development in depth and investigate its impact on the three most important paradigms in the field Rule-based, Example-based and Statistical MT. In addition, we use the Trans-Booster architecture as a promising alternative to current Multi-Engine MT techniques. We evaluate TransBooster on the language pair Engl~sh-+Spanish with a combination of automatic and manual evaluation metrics, prov~ding a rigorous analysis of the potential and shortcomings of our approach

    Utilizing Computer Programming to Analyze Post-Tonal Music: A Segmentation and Contour Analysis of Twentieth-Century Music for Solo Flute

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    Two concepts will be synthesized in this dissertation: 1) the creation of accessible computer applications for melodic segmentation and contour reduction and 2) the application of segmentation and contour reduction to analyze twentieth-century post-tonal works for unaccompanied flute. Two analytical methodologies have been chosen: James Tenney and Larry Polanski\u27s Gestalt segmentation theory and Robert Schultz\u27s refinement of Robert Morris\u27s contour reduction algorithm. The investigation also utilizes Robert Schultz\u27s concept of diachronic-transformational analysis in conjunction with contour reduction. While both segmentation and contour reduction are invaluable analytical tools, they are meticulous and time-consuming processes. Computer implementation of these algorithmic procedures produces quick and accurate results while reducing analyst fatigue and human error. Microsoft Excel is used to complete melodic segmentation. Java programming language is used to create a contour reduction application. Each implementation greatly reduces the time needed to segment and analyze a melody. Computer programming is combined with pitch class set analysis to produce informed and expressive musical interpretations

    USING ASTROBIOLOGY AS A PLATFORM TO STUDY THE IMPACT ON THE MATHEMATICAL CONTENT KNOWLEDGE AND PEDAGOGICAL CONTENT KNOWLEDGE OF ELEMENTARY EDUCATION MAJORS

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    Early mathematical skills have long been hailed as a cornerstone and as the best predictor of later success in mathematics and literacy. This perception highlights the importance of elementary educator’s mathematical content knowledge (MCK) and pedagogical content knowledge (PCK). This study explored a novel approach to motivating and facilitating preservice elementary educators’ engagement in an interdisciplinary context. Astrobiology is a growing interdisciplinary field with extraordinary educational potential. It has the potential to provide an exciting science framework structure to mathematics for preservice educators. Due to its interdisciplinary content, astrobiology offers preservice educators an opportunity to see math content through a science lens, an approach that may appeal to students with diverse interests. Although astrobiology research has been on the rise and has contributed greatly to the science field and to society, more research on astrobiology education in schools and colleges needs to be done to understand the best pedagogical approaches to such a diverse topic that encompasses multiple disciplines. Using a quasi-experimental design, this study examines whether the implementation of astrobiology modules focused on science questions could be used as an effective platform to deliver mathematical instruction that focuses on MCK and PCK. Specifically, this dissertation investigates the impact of such modules on preservice elementary educators’ MCK and PCK, both quantitatively and qualitatively. A comprehensive analysis involving nonparametric statistics and qualitative analysis found insufficient sample evidence at the alpha level of 0.05 (α=0.05) to warrant rejection that the astrobiology based mathematical modules had no effect on the preservice teachers’ MCK or PCK. However, one test found a positive correlation between the module and an increase in astrobiology knowledge. The qualitative examination exposed a decrease in the quality of responses for the MCK and PCK areas. This affect could be attributed to the limiting factors of the study. These factors have implications for both teaching future research in the intersection of astrobiology education and MCK and PCK

    Automatic 2D and 3D segmentation of liver from Computerised Tomography.

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    As part of the diagnosis of liver disease, a Computerised Tomography (CT) scan is taken of the patient, which the clinician then uses for assistance in determining the presence and extent of the disease. This thesis presents the background, methodology, results and future work of a project that employs automated methods to segment liver tissue. The clinical motivation behind this work is the desire to facilitate the diagnosis of liver disease such as cirrhosis or cancer, assist in volume determination for liver transplantation, and possibly assist in measuring the effect of any treatment given to the liver. Previous attempts at automatic segmentation of liver tissue have relied on 2D, low-level segmentation techniques, such as thresholding and mathematical morphology, to obtain the basic liver structure. The derived boundary can then be smoothed or refined using more advanced methods. The 2D results presented in this thesis improve greatly on this previous work by using a topology adaptive active contour model to accurately segment liver tissue from CT images. The use of conventional snakes for liver segmentation is difficult due to the presence of other organs closely surrounding the liver this new technique avoids this problem by adding an inflationary force to the basic snake equation, and initialising the snake inside the liver. The concepts underlying the 2D technique are extended to 3D, and results of full 3D segmentation of the liver are presented. The 3D technique makes use of an inflationary active surface model which is adaptively reparameterised, according to its size and local curvature, in order that it may more accurately segment the organ. Statistical analysis of the accuracy of the segmentation is presented for 18 healthy liver datasets, and results of the segmentation of unhealthy livers are also shown. The novel work developed during the course of this project has possibilities for use in other areas of medical imaging research, for example the segmentation of internal liver structures, and the segmentation and classification of unhealthy tissue. The possibilities of this future work are discussed towards the end of the report

    Twentieth Annual Conference on Manual Control, Volume 1

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    The 48 papers presented were devoted to humanopeator modeling, application of models to simulation and operational environments, aircraft handling qualities, teleopertors, fault diagnosis, and biodynamics

    Herramientas educativas para facilitar la adopción de la ingeniería de lenguajes software entre los desarrolladores informáticos

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    Históricamente, la materia de construcción de compiladores y procesadores de lenguaje es considerada por los estudiantes de ingeniería en informática como una materia difícil. Esto es debido, por una parte, a la naturaleza formal de las herramientas de especificación y diseño utilizadas, y, por otra, a la aplicación adecuada de diferentes técnicas sistemáticas de desarrollo para obtener los procesadores finales a partir de sus especificaciones. En esta tesis se aborda esta problemática en el caso particular de las gramáticas de atributos como formalismo básico de especificación. La tesis aborda, primeramente la concepción de una estrategia para facilitar la comprensión de los aspectos básicos de las especificaciones basadas en gramáticas de atributos, así como el soporte software de dicha estrategia. La estrategia propone un enfoque dirigido por problemas, en los que el alumno debe emular el proceso de evaluación semántica sobre distintos supuestos de procesamiento de frases de acuerdo con gramáticas de atributos. Para soportar dicha estrategia, se ha desarrollado un sistema denominado Evaluators, que, tomando como entrada baterías de ejercicios sobre evaluación semántica, produce automáticamente simuladores interactivos que los estudiantes pueden utilizar para resolver dichos ejercicios. El sistema proporciona, así mismo, una herramienta de autoría, que puede ser utilizada por los docentes para proporcionar los ejercicios, así como una herramienta de análisis, que permite trazar el comportamiento de los estudiantes durante la resolución de los mismos en los simuladores generados. Respecto a dichos simuladores, la herramienta es capaz de generar simulaciones de dos tipos: simuladores basados en juegos serios, y simulaciones interactivas basadas en las representaciones abstractas convencionales utilizadas en la materia. La tesis presenta, así mismo, diversos resultados de evaluación de la herramienta, tanto con estudiantes como con docentes, que evidencian la utilidad práctica de la misma. Por último, la tesis abstrae también el modelo de proceso utilizado en la construcción de la misma..

    CEAS/AIAA/ICASE/NASA Langley International Forum on Aeroelasticity and Structural Dynamics 1999

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    The proceedings of a workshop sponsored by the Confederation of European Aerospace Societies (CEAS), the American Institute of Aeronautics and Astronautics (AIAA), the National Aeronautics and Space Administration (NASA), Washington, D.C., and the Institute for Computer Applications in Science and Engineering (ICASE), Hampton, Virginia, and held in Williamsburg, Virginia June 22-25, 1999 represent a collection of the latest advances in aeroelasticity and structural dynamics from the world community. Research in the areas of unsteady aerodynamics and aeroelasticity, structural modeling and optimization, active control and adaptive structures, landing dynamics, certification and qualification, and validation testing are highlighted in the collection of papers. The wide range of results will lead to advances in the prediction and control of the structural response of aircraft and spacecraft
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