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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Wavelets and short time fourier transforms on ultrasonic doppler signals for pregnancy determination in sheep

Hertzog, P.E., Jordaan, G.D. January 2006 (has links)
Published Article / The reproductive status of animals is of utmost importance to the modern farmer. Decisions concerning the management of the flock are influenced by the knowledge of the percentage of animals that are pregnant at any specific time. The aim of the project was to gain knowledge for the development of an instrument that is affordable and with which a farmer can do pregnancy determination himself/herself, thereby enabling him/her to make the correct management decisions. Experimental data were obtained from pregnant Dorper ewes with the aid of a portable Doppler instrument. Using real data as input, simulations of Wavelet and Short Time Fourier Transforms (STF) were done in MathCAD. In the simulations known levels of noise were added to the Doppler signals. Satisfactory results were obtained from the simulations of Wavelet Transforms. In the simulation of the Wavelet Transforms, signals with a SNR of -6.5 dB were successfully identified. It can thus be concluded that Wavelet Transforms can be used successfully for the detection of the fetal heartbeat in noisy ultrasonic Doppler signals.
52

FFT Bit Templating – A Technique for Making Amplitude and Frequency Measurements of a BPSK Modulated Signal

Shockey, Bruce 10 1900 (has links)
International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / In many spacecraft receiver applications, the Fast Fourier Transform (FFT) provides a powerful tool for measuring the amplitude and frequency of an unmodulated RF signal. By increasing the FFT acquisition time, tiny signals can be coaxed from the noise and their frequency measured by determining which frequency bin the signal energy appears. The greater the acquisition time, the narrower the bin bandwidth and the more accurate the frequency measurement. In modern satellite operations it is often desirable for the receiver to measure the frequency of a carrier which is modulated with BPSK data. The presence of the BPSK data limits the FFT acquisition time since the signal may switch polarities a number of times while the FFT samples are being acquired. This polarity switching spreads the signal energy into multiple frequency bins making frequency measurement difficult or impossible. The Bit Templating Technique, used for the first time in the CMC Electronics Cincinnati TDRSS / BPSK Spacecraft Receiver, collects the modulated waveform energy back into a signal bin so that accurate amplitude and frequency information can be calculated.
53

Acquiring PN Codes Without Serial Searches Using Modified Correlation Loops

Yadati, Uday, Kosbar, Kurt 10 1900 (has links)
International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / This paper analyzes the performance of a modified correlation, or delay-locked loop (DLL). These devices typically cross-correlate the received signal with a differentiated version of the originally transmitted signal. This paper describes some interesting properties the loop assumes when the differentiator is replaced by a Hilbert transform. The loop will still track the timing offset of the code, but it will also be able to acquire the signal when the initial offset is greater than one chip time. The new loop may also be superior to traditional DLL in low SNR environments, since it is much less likely to lose lock. Since the new loop is highly non-linear, it is studied through the use of computer simulations.
54

Fourier-Mukai transforms and stability conditions on abelian threefolds

Piyaratne, Hathurusinghege Dulip Bandara January 2014 (has links)
Construction of Bridgeland stability conditions on a given Calabi-Yau threefold is an important problem and this thesis realizes the rst known examples of such stability conditions. More precisely, we construct a dense family of stability conditions on the derived category of coherent sheaves on a principally polarized abelian threefold X with Picard rank one. In particular, we show that the conjectural construction proposed by Bayer, Macr and Toda gives rise to Bridgeland stability conditions on X. First we reduce the requirement of the Bogomolov-Gieseker type inequalities to a smaller class of tilt stable objects which are essentially minimal objects of the conjectural stability condition hearts for a given smooth projective threefold. Then we use the Fourier-Mukai theory to prove the strong Bogomolov-Gieseker type inequalities for these minimal objects of X. This is done by showing any Fourier-Mukai transform of X gives an equivalence of abelian categories which are double tilts of coherent sheaves.
55

Detecção de formas circulares utilizando a Transformada de Hough, desenvolvida no ambiente Windows / not available

Bentes, Paulo César Lucena 18 March 1997 (has links)
Neste trabalho é descrito um software denominado Scanc implementado no ambiente Windows, para a identificação de formas circulares em imagens digitais do tipo BMP. Dois métodos foram implementados para esse fim: a Transformada de Hough e Template Matching. Incluídos neste software encontram-se recursos para detecção de bordas e binarização da imagem, entre outros. O software tem aplicação nas mais diversas áreas, que requeiram a identificação de formas circulares. / The present work describes a software named Scanc, developed for circular pattern identification in digital bitmap images (BMP). Scanc was developed for Microsoft Windows environment and it takes advantage of two methods: Hough Transform and Template Matching. Image tools such as border detection and binarization are also available among other resources. The software finds several applications wherever circular forms identification is requered.
56

A new method of pricing multi-options using Mellin transforms and integral equations

Vasilieva, Olesya January 2009 (has links)
<p>In this thesis a new method for the option pricing will be introduced with the help of the Mellin transforms. Firstly, the Mellin transform techniques for options on a single underlying stock is presented.After that basket options will be considered. Finally, an improvement of existing numerical results applied to Mellin transforms for 1-basket and 2-basket American Put Option will be discussed concisely. Our approach does not require either variable transformations or solving diffusion equations.</p> / thesis
57

Directional time-frequency analysis with applications

Sansing, Christopher, January 2006 (has links)
Thesis (Ph.D.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (March 1, 2007) Vita. Includes bibliographical references.
58

A new method of pricing multi-options using Mellin transforms and integral equations

Vasilieva, Olesya January 2009 (has links)
In this thesis a new method for the option pricing will be introduced with the help of the Mellin transforms. Firstly, the Mellin transform techniques for options on a single underlying stock is presented.After that basket options will be considered. Finally, an improvement of existing numerical results applied to Mellin transforms for 1-basket and 2-basket American Put Option will be discussed concisely. Our approach does not require either variable transformations or solving diffusion equations. / thesis
59

Windowed linear canonical transform and its applications

Xu, Rui Hui January 2011 (has links)
University of Macau / Faculty of Science and Technology / Department of Mathematics
60

Modeling Software with UML¡ÐA Case Study of Personnel Leave System

Chang, Jei-Chen 23 July 2007 (has links)
Modeling software with the model driven architecture (MDA) concept and unified modeling language (UML) has become a new trend for the objected-oriented systems analysis and design. Several CASE tools which embed MDA concept and UML have been introduced to facilitate the transformation from platform independent model (PIM, i.e., class diagram) to platform specific model (PSM) in order to enhance the efficiency of software development. In this work, we present a systematic methodology which integrates the concept of MDA and UML with CASE tool to refine the process of UML transformation. A personnel leave prototype system is implemented to illustrate the concepts, application, and advantages of the proposed methodology. With this approach, software developers can construct the PIM efficiently and thereby enhance the efficiency of system development.

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