Τα κυκλοφοριακά πλήγματα είναι ένα φαινόμενο που συμβαίνει καθημερινά στα οδικά δίκτυα και προκαλεί από μεγάλες καθυστερήσεις μέχρι σοβαρά ατυχήματα. Η παρούσα μελέτη αφορά στην μικροσκοπική ανάλυση κυκλοφοριακού πλήγματος με την εφαρμογή του μετασχηματισμού wavelet. Με τη βοήθεια του μαθηματικού αυτού εργαλείου για την επεξεργασία των σημάτων της κυκλοφορίας, εξετάζονται 20 διαφορετικές περιπτώσεις συμβάντος, κάθε μία εκ των οποίων περιλαμβάνει ένα πλήγμα. Αποτυπώνονται οι τροχιές των εμπλεκόμενων οχημάτων, υπολογίζονται οι χρονοσειρές των ταχυτήτων τους και από τις κατανομές της ενέργειας wavelet προκύπτουν με ακρίβεια τα σημεία έναρξης και λήξη του πλήγματος. Τα σημεία αυτά χαρακτηρίζουν τον τρόπο που διαδίδονται τα πλήγματα από όχημα σε όχημα και από αυτά προκύπτει το «μονοπάτι» και η ταχύτητα διάδοσης πλήγματος. Τα πλήγματα διαχωρίζονται σε απλά και σύνθετα και αναλύεται η συσχέτιση των ταχυτήτων διάδοσης στα υπό – πλήγματα των σύνθετων πληγμάτων, καθώς και η επίδραση της παρουσίας μεγάλης χρονοαπόστασης στη διάδοση αυτών των πληγμάτων. / One of the most common problems in road networks is the shockwave, which can cause enormous delays and serious problems to traffic. This study presents a microscopic analysis of shockwave, using wavelet transform. Using wavelet transform for traffic signal processing, 20 shockwaves were examinated. By watching videos, trajectories of every single vehicle that was involved in these shockwaves are obtained and speeds are computed. Having the wavelet – based energy distributions, start and end points are marked in the trajectories diagrams. These points characterize the way the shockwave propagates from vehicle to vehicle. Marking these points we can find the shockwave propagation path and we can compute the shockwave propagation speed. A shockwave can be simple or complex. Thus, we can analyze the correlation between the shockwave propagation speeds of the parts of a complex shockwave; and the effect of time headway on shockwave propagation.

Made available in DSpace on 2014-06-11T19:25:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-07-10Bitstream added on 2014-06-13T19:53:23Z : No. of bitstreams: 1 varanis_mvm_me_rcla.pdf: 4826016 bytes, checksum: ab2c8b052e0a038577280ce930b14260 (MD5) / O estudo de vibrações diz respeito aos movimentos oscilatórios de corpos e às forças que lhes são associadas. Todos os corpos dotados de massa e elasticidade são capazes de vibrar. Deste modo, a maior parte das máquinas e estruturas estão sujeitas a certos graus de vibração A maioria das atividades humanas envolve alguma forma de vibração. O estudo do comportamento dinâmico dessas oscilações mecânicas é o objetivo deste trabalho e para isto propomos um sistema de massas concentradas e com dois graus de liberdade. O sistema será excitado por forças externas, entre elas ondas de terremoto. Com simulações numéricas estudamos o sistema, usando a transformada rápida de Fourier, transformada wavelet. / The study of vibration concerns oscillatory movement of bodies and the forces they are associated. All bodies that have mass and elasticity are able to vibrate. Thus, most of the machines and structures are subject to certain degrees of vibration most human activities involve some form of vibration. The study of the dynamic behavior of these mechanical oscillations is the objective of this work and to propose that a system of weights and concentrated with two degrees of freedom. The system will be excited by external forces, including waves of earthquake. With numerical simulations studied the system, using the fast Fourier transform, wavelet transform.

No / In this work we have studied the performance of MIMO-DWT based multicarrier system using the feedback circuit from the receiver to the transmitter to understand the channel state information (CSI) and to create a steering matrix in order to constructively combine the received signal at the receiver which provides the advantage of keeping the burden of processing at the transmitter which has more power and less constraints.

Effective image compression requires a non-expansive discrete wavelet transform (DWT) be employed; consequently, image border extension is a critical issue. Ideally, the image border extension method should not introduce distortion under compression. It has been shown in literature that symmetric extension performs better than periodic extension. However, the non-expansive, symmetric extension using fast Fourier transform and circular convolution DWT methods require symmetric filters. This precludes orthogonal wavelets for image compression since they cannot simultaneously possess the desirable properties of orthogonality and symmetry. Thus, biorthogonal wavelets have been the de facto standard for image compression applications. The viability of symmetric extension with biorthogonal wavelets is the primary reason cited for their superior performance. Recent matrix-based techniques for computing a non-expansive DWT have suggested the possibility of implementing symmetric extension with orthogonal wavelets. For the first time, this thesis analyzes and compares orthogonal and biorthogonal wavelets with symmetric extension. Our results indicate a significant performance improvement for orthogonal wavelets when they employ symmetric extension. Furthermore, our analysis also identifies that linear (or near-linear) phase filters are critical to compression performance---an issue that has not been recognized to date. We also demonstrate that biorthogonal and orthogonal wavelets generate similar compression performance when they have similar filter properties and both employ symmetric extension. The biorthogonal wavelets indicate a slight performance advantage for low frequency images; however, this advantage is significantly smaller than recently published results and is explained in terms of wavelet properties not previously considered. / Master of Science

The sun is constantly emitting electrons and ions as magnetized plasma, forming the solar wind and carrying with it the sun’s rotating magnetic field. The solar wind subsequently interacts with Earth’s magnetosphere and the magnetospheres of other planets. Occasionally large amounts of magnetized plasma are released at one time in a Corona mass ejection (CME). When the CME interacts with Earth’s magnetic field, it induces perturbations that may have a significant impact on critical infrastructure, for instance, by disturbing communication systems, and inducing currents on pipelines and electric power lines, which in turn may cause increased corrosion or blackouts, among other effects. In this dissertation, we analyze measured electrical signals provided to us by the Finnish Meteorological Institute, which were induced by geomagnetic storms on pipelines located in Finland and recorded in 2003. Specifically, we perform a wavelet leader multifractal analysis of these current signals to generate singularity spectra, and then using the bootstrapping technique, we apply statistical tests to show that these signals exhibit multifractal characteristics. We also performed surrogate testing to show that these characteristics were unique to the signal. / Ph.D. / Earth’s weather affects all of us every day. The solar space environment has weather of its own that affects us as well. Storms of a size that far exceed anything on Earth can impact Earth and affect our infrastructure. One of the most powerful phenomena that occur, called solar corona mass ejections, results when the sun ejects a large amount of plasma. This can interact with the Earth’s magnetic field, which in turn induces perturbations that may have a significant impact on critical infrastructure, for instance, by disturbing communication systems, and inducing currents on pipelines and electric power lines. The currents can cause increased corrosion or blackouts, among other effects. In this dissertation, we analyze measured electrical signals provided to us by the Finnish Meteorological Institute, which were induced by geomagnetic storms on pipelines located in Finland and recorded in 2003. Specifically, we perform a statistical analysis of these current signals to decide whether they exhibit multifractal characteristics.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Conventional video image transmission requires large data bandwidths, whether the signals are transmitted in analog or digital form. Many applications are limited to bandwidths that will not support image transmission unless high compression ratios are employed. Video compression techniques based on wavelet functions provide high data compression while preserving image quality, but are computationally demanding. Recently available high-integration devices that utilize wavelet basis functions for video compression have made possible low-cost high-performance video compression systems. Image data is more useful when provided with other data such as position information, telemetry, or other user data. This paper describes the technology, features, and limitations of a versatile low data rate system incorporating compressed video data.

No description available.

In this work we reconstruct Quantum Mechanical wave functions for some confining potentials, using the moment-wavelet method of Handy and Murenzi. This method consists in transforming the Schrodinger equation into an equivalent continuous wavelet transform (CWT) representation involving scaled and translated moments, µ1/ α,b (p)=∫χpe-Q\( Ψ(x +b), where ϐ -Q becomes the mother wavelet. The discrete bound states are determined through a multiscale process involving the integration of a finite number of coupled linear first order differential equation in the moments µ1/ α,b (p). The underlying initial value problem depends on moment quantization methods to determine the infinite scale (a = ∞) moments and energy. Using this method we calculate the energies and wavefunctions for the first two quantum states of quartic and dectic anharmonic oscillator potentials, V(x) = mχ2 + gχ4, V(χ) = χ 2+χ10 respectively.

As bolsas para coleta de sangue necessitam cuidados técnicos que assegurem sua esterilidade biológica durante o processo de fabricação até a entrega do produto final. As bolsas para coleta de sangue não devem conter qualquer tipo de resíduo, para que o seu uso ou conteúdo não seja comprometido causando diversos transtornos. É preciso eliminar o risco de contaminação; no entanto muitas empresas fazem a inspeção de bolsas para coleta de sangue visualmente, a olho nu, por funcionários treinados no uso de equipamento simples, o qual não pode garantir que todas as bolsas estejam livres de resíduos, por depender do fator humano. Para assegurar a esterilização das bolsas comercializadas, este trabalho propõe uma metodologia para automação de um sistema de visão computacional baseado em conjunto de técnica de extração de características de imagens e reconhecimento de padrões para detectar resíduos em imagens de bolsas para coleta de sangue durante o processo de fabricação, e assim, melhorar a qualidade das bolsas comercializadas. Os resíduos encontrados nas imagens capturadas se apresentam como componentes de alta freqüência. A metodologia proposta utiliza a Transformada Wavelet (Wavelet de Haar) em dois níveis de decomposição, como filtro passa - alta para destacar as altas freqüências, e assim detectar a existência de resíduos nas imagens capturadas. Os resultados obtidos com a inspeção visual manual realizada em bolsas para coleta de sangue, mostram que existem resultados divergentes na análise de uma mesma bolsa, o que reforça a necessidade de automatização dessa tarefa para que sejam obtidos resultados mais uniformes com padrões definidos, e dessa maneira melhorar a qualidade das bolsas comercializadas para coleta de sangue. / The blood bags require technician attention to assure its biological sterility in the process of manufacture and in the final product. The blood bags must not contain any type of waste, so that its use or content is not compromised causing various disorders; it is necessary to eliminate any contamination risk; however many companies perform a visually inspection of the blood bags, by naked eye, by trained employees in the use of a simple equipment, which cannot guarantee that all the bags are residue-free because depending on the human factor. The residues showed on the pictures were characterized as high frequency components. So the proposed methodology applies two levels decomposition of Haar´s Wavelet as high pass filter to evidence high frequencies, and to evidence the residues at the pictures and to evidence the existence of residues on the captured pictures. To assure the sterilization of the commercialized blood bags, this work propose a methodology of an automated computational system based in a group of techniques of image characteristics extraction and recognition patterns to detect residues in blood bag images in the process of manufacture, in order to improve the quality of the commercialized blood bags.This technique is used as high-pass filter, to detach the high frequencies, using a Haar-wavelet in two decomposition levels. The results obtained with the manual visual inspection indicate that were found divergent results in the analysis of the same blood bag, which reinforces the necessity of the automation of this task in order to obtain more uniform results with defined standards.

This thesis explains and tests a wavelet based implicit numerical method for the solving of partial differential equations. Intended for problems with localized small-scale interactions, the method exploits the form of the wavelet decomposition to divide the implicit system created by the time discretization into multiple, smaller, systems that can be solved sequentially. Included are tests of this method on linear and non-linear problems, with both its results and the time required to calculate them compared to basic models. It was found that the method requires less computational effort than the high resolution control results. Furthermore, the method showed convergence towards high resolution control results.