Dissertations / Theses on the topic 'The cross-correlation function'

This dissertation addresses the problem of inverting two-dimensional seismic data to determine the compressional wave velocity as a function of the spatial position in the medium. An automatic procedure for velocity estimation is set up using a bi-dimensional cross-correlation function to compare the modelled seismograms with the data. The standard wave-equation traveltime inversion algorithm treats each recorded seismic trace independently, and ignores the offset-dependence of reflected and diffracted arrivals in an ensemble of traces in a shot gather. My new inversion method, wave-equation traveltime-<I>offset</I> inversion, focuses on reflected or diffracted waveforms and introduces the bi-dimensional (offset-time) cross-correlation function to tackle this offset dependence. The velocity model is updated using the current velocity model, the observed pressure field, and the fields computed by reverse time propagation of two pseudo-residual functions acting as sources in a particular location. The wave-equation traveltime-offset inversion reconstructs the low frequency content of the velocity model when transmitted arrivals are used. Combined with the full waveform inversion, it succeeds in inverting a synthetic fault model in the crosshole configuration. The proposed method also succeeds in inverting surface reflection datasets while the standard traveltime inversion fails. By taking into account the moveout between traces, the convergence is more stable than with the conventional method. When inverting datasets with surface reflection geometries, the dominant event and the velocity above it are recovered using the traveltime and offset information. The remaining interfaces are defined as well. However, as there is a gap in resolution between the long and short wavelengths, the blocky variations in the velocity model are not observed.

Maintenance of stable arterial blood pressure during orthostatic challenges is a major problem after spinal cord injury (SCI). Since early participation in rehabilitation is critically important in reducing long term morbidity, recovering the ability to regulate blood pressure during therapy is essential for individuals with SCI. The objective of our study was to investigate short term cardiovascular function of able-bodied (AB), paraplegic (PARA) and tetraplegic (TETRA) subjects in response to head up tilt (HUT) as an early indicator of autonomic damage that might forewarn of future orthostatic regulatory problems. We acquired cardiovascular variables from able-bodied (AB; n=11), paraplegic (PARA; n=5) and tetraplegic (TETRA; n=5) subjects in response to HUT. The SCI patients in both groups were in their first two months post injury. Data were recorded at rest and during 7 min each at 20??, 40??, 60?? and 80?? HUT. Techniques used to estimate regulatory capability and reflex activity included: Mean values and spectral power of heart rate (HR) and arterial blood pressure (BP), baroreflex sequence measurements and cross correlation between HR and systolic blood pressure (SBP). An index of baroreflex sensitivity (BRS), baroreflex effectiveness index (BEI), and the percentage occurrence of systolic blood pressure (BP) ramps and baroreflex sequences were calculated from baroreflex sequence measurements. The spectral power of HR and BP, the cross correlation of systolic BP and heart rate (HR) were examined in low frequency (LF: 0.04-0.15 Hz) and high frequency (HF: 0.15-0.4 Hz) ranges. The BRS index was significantly (p andlt; 0.05) decreased from supine to 80o HUT in AB and TETRA. This index in PARA was the lowest at each tilt position in the three groups, and decreased with tilt. The percentage of heart beats involved in systolic BP ramps and in baroreflex sequences significantly (pandlt;0.05) rose from supine to 80o HUT in AB, was relatively unchanged in PARA and declined in TETRA. Both of these indexes were significantly (pandlt;0.05) lowerin the SCI than in the AB group at each tilt level. The BEI values were greatest in AB, and declined with tilt in all groups. Spinal cord injured patients had less power of BP and HR fluctuations than AB in both LF and HF regions. The LF spectral power of BP and HR increased with tilt in AB, remained unchanged in PARA and decreased in TETRA. The HF spectral power of HR decreased in all three groups. The peak HR / BP cross correlation in the LF region was greatest in AB, and significantly (pandlt;0.05) increased during HUT in AB, remained fairly constant in PARA, and declined in TETRA. The peak cross correlation in the HF region significantly (pandlt;0.05) decreased with tilt in all groups, and the SCI group had lower values than AB at each tilt level. We conclude that both PARA and TETRA had a smaller percentage of SBP ramps, BRS, and lower BEI than AB, likely indicating decreased stimulation of arterial baroreceptors, and less engagement of feedback control. The mixed sympathetic, parasympathetic innervations of paraplegics, or their elevated HR, may contribute to their significantly lower BRS. Our data indicate that the pathways utilized to evoke baroreflex regulation of HR are compromised by SCI and this loss may be a major contributor to the decrease in orthostatic tolerance following injury.

L'interférométrie de bruit ambiant est une approche pour estimer la réponse impulsionnelle entre deux récepteurs sans source active. Cette thèse contribue à l'évaluation de la robustesse et de la précision de la reconstruction de la fonction de Green par la corrélation du bruit ambiant dans les milieux réverbérants. Plus précisément, on distingue les rôles respectifs de la partie balistique et coda des signaux dans les corrélations. Ensuite, nous nous concentrons sur un milieu réverbérant incluant un diffuseur. Nous estimons de manière passive la force du diffuseur en utilisant l'interférométrie du bruit ambiant. Dans la dernière partie de ce travail, nous nous concentrons sur un milieu réverbérant contenant les inclusions résonantes. Notre but est d'évaluer le comportement de la corrélation dans ce type de milieu. Nous avons construit un de ces matériaux au laboratoire qui est constitué des tiges verticales à la surface d'une plaque mince élastique. Nous trouvons que les différents comportements sont bien cohérents avec les régimes qui correspondent à la bande de propagation ou interdite. Comme la partie sismique, nous appliquons la technique de corrélation aux données réelles récupérées lors de l'expérience METAFORET. Nos résultats sont sont en accord avec le comportement diffusant des arbres dans les gammes de fréquence correspondante<br>Ambient-noise interferometry is an approach to estimate the transient response between two receivers without an active source. The method consists of cross-correlating recordings of ambient vibrations at a pair of passive instruments that act only as receivers. This dissertation contributes to evaluating the robustness and accuracy of Green's function reconstruction by cross-correlation of noise, disentangling the respective roles of ballistic and reverberated ('coda') signals. We focus our study on a strongly reverberating medium. We conduct a suite of experiments on a highly reverberating thin duralumin plate. We find that the coda of the arrivals contribute the most to retrieval of the Green's function. We also develop an analytical model that predicts the dependence of symmetry of the cross-correlations on the number of sources. Next, we focus on a reverberating medium with a scatterer. We passively estimate the scattering strength of the scatterer by implementing ambient-noise interferometry. In the last part, we focus on a reverberating medium with locally resonant scatterers which acts as a metamaterial. Our objective is to assess the behaviour of the cross-correlation in such a medium. We build an example of such materials in the laboratory by attaching an array of rods, arranged in a sub-wavelength order, to the surface of a thin elastic plate. We find different behaviours which are consistent with the regimes that correspond to propagation band and bandgap. We next apply the cross-correlation technique to the real data obtained in METAFORET experiment. Our findings are consistent with the resonating behaviour of trees at the corresponding frequency bands

Radial velocities measured from near-infrared (NIR) spectra are a potential tool to search for extrasolar planets around cool stars. High resolution infrared spectrographs now available reach the high precision of visible instruments, with a constant improvement over time. GIANO is an infrared echelle spectrograph and it is a powerful tool to provide high resolution spectra for accurate radial velocity measurements of exo-planets and for chemical and dynamical studies of stellar or extragalactic objects. No other IR instruments have the GIANO's capability to cover the entire NIR wavelength range. In this work we develop an ensemble of IDL procedures to measure high precision radial velocities on a few GIANO spectra acquired during the commissioning run, using the telluric lines as wevelength reference. In Section 1.1 various exoplanet search methods are described. They exploit different properties of the planetary system. In Section 1.2 we describe the exoplanet population discovered trough the different methods. In Section 1.3 we explain motivations for NIR radial velocities and the challenges related the main issue that has limited the pursuit of high-precision NIR radial velocity, that is, the lack of a suitable calibration method. We briefly describe calibration methods in the visible and the solutions for IR calibration, for instance, the use of telluric lines. The latter has advantages and problems, described in detail. In this work we use telluric lines as wavelength reference. In Section 1.4 the Cross Correlation Function (CCF) method is described. This method is widely used to measure the radial velocities.In Section 1.5 we describe GIANO and its main science targets. In Chapter 2 observational data obtained with GIANO spectrograph are presented and the choice criteria are reported. In Chapter 3 we describe the detail of the analysis and examine in depth the flow chart reported in Section 3.1. In Chapter 4 we give the radial velocities measured with our IDL procedure for all available targets. We obtain an rms scatter in radial velocities of about 7 m/s. Finally, we conclude that GIANO can be used to measure radial velocities of late type stars with an accuracy close to or better than 10 m/s, using telluric lines as wevelength reference. In 2014 September GIANO is being operative at TNG for Science Verification and more observational data will allow to further refine this analysis.

This thesis presents the implementation and validation of a new methodology developed by Glegg et al. (2004) for solving the trailing edge noise problem. This method is based on the premises that the noise produced by a surface can be computed by the integral of the cross product between the velocity and vorticity fields, of the boundary layer and shed vorticity (Howe (1978)). To extract the source terms, proper orthogonal decomposition is applied to the velocity cross spectrum to extract modes of the unsteady velocity and vorticity. The new formulation of the trailing edge noise problem by Glegg et al. (2004) is attractive because it applies to the high frequencies of interest but does not require an excessive computational effort. Also, the nature of the formulation permits the identification of the modes producing the noise and their associated velocity fluctuations as well as the regions of the boundary layer responsible for the noise production. The source terms were obtained using the direct numerical simulation of a turbulent channel flow by Moser et al. (1998). Two-point velocity and vorticity statistics of this data set were obtained by averaging 41 instantaneous fields. For comparisons purposes, experimental boundary layer data by Adrian et al. (2000) was chosen. Statistical reduction of 50 velocity fields obtained by particle image velocimetry was performed and analysis of the two-point correlation function showed features similar to the DNS data case. Also, proper orthogonal decomposition revealed identical dominant modes and eddy structures in the flow, therefore justifying considering the channel flow as an external boundary layer for noise calculations. Comparison of noise predictions with experimental data from Brooks et al. (1989) showed realistic results with the largest discrepancies, on the order of 5 dB, occurring at the lowest frequencies. The DNS results are least applicable at these frequencies, since these correspond to the longest streamwise lengthscales, which are the most affected by the periodicity conditions used in the DNS and also are the least representative of the turbulence in an external boundary layer flow. Most of the noise was shown to be produced by low-frequency streamwise velocity modes in the bottom 10% of the boundary layer and locations closest to the wall. Only 6 modes were required to obtain noise levels within 1 dB of the total noise. Finally, the method for predicting spatial velocity correlation from Reynolds stress data in wake flows, originally developed by Devenport et al. (1999, 2001) and Devenport and Glegg (2001), was adapted to boundary-layer type flows. This method, using Reynolds stresses and the prescription of a lengthscale to extrapolate the full two-point correlation, was shown to produce best results for a lengthscale prescribed as proportional to the turbulent macroscale. Noise predictions using modeled two-point statistics showed good agreement with the DNS inferred data in all but frequency magnitude, a probable consequence of the modeling of the correlation function in the streamwise direction. Other quantities associated to noise were seen to be similar to the ones obtained using the DNS.<br>Master of Science

Магістерська робота на тему «Алгоритм кореляційно-екстремального стеження за безпілотним літальним апаратом за даними відеоспостереження» складається з 8 розділів, 83 сторінки, 1 додатку, 60 ілюстрацій по тексту роботи та 20 таблиць. Використано 11 посилань. На сьогоднішній день прогресивний розвиток пілотної та безпілотної авіації, систем управлінням повітряними та наземними об'єктами пересування, створює необхідність у розробці технологій, що виявляють та супроводжують об'єкти у просторі. Найбільш широке застосування вони віднайшли у задачах навігації, космічного моніторингу Землі, забезпечення безпеки, бортових систем, що встановлюються у літаках, гелікоптерах та автомобілях, та охоронних послуг. Необхідність у використання методів виявлення та супроводження зростає у зв’язку з розширенням області застосування БПЛА, що можуть бути об’єктами-правопорушниками. Підвищення ефективності оптико-електронних систем необхідно для задач охорони та захисту закритих територій від несакціонованого проникнення, забезпечення їх приватності від безпілотних літаючих апаратів. Сучасні БПЛА можуть мати не тільки маленькі розміри та високу автономність, але і надзвичайно високу маневреність. Як наслідок, постійно підвищується вимоги комплексів, що обробляють поставлені цілі, а тому це приводить до поліпшення вже існуючих технологій та розробки нових методів і алгоритмів для вирішення поставлених задач. В роботі розглянута розробка та аналіз алгоритм кореляційно-екстремального стеження за безпілотним літальним апаратом за даними відеоспостережень. Метою дослідження є покращення характеристик стеження за малорозмірними БПЛА системою відеоспостереження, шляхом розробки кореляційно-екстремального алгоритма стеження. Об’єкт дослідження – процес стеження за малорозмірними БПЛА системою відеоспостереження. Предмет дослідження – методи стеження за малорозмірними БПЛА за даними відеоспостережень. Для досягнення поставленої мети необхідно вирішити такі завдання: - провести аналіз сучасних телевізійних систем відеоспостереження; - виконати аналіз кореляційно-екстремальних методів зіставлення зображень; - розглянути можливості застосування метода калманівської фільтрації для стеження за точковими цілями; - розробити алгоритм кореляційно-екстремального стеження за малорозмірним БПЛА на основі методу калманівської фільтрації; - оцінити ефективність розробленого алгоритму за допомогою статичного моделювання на ЕОМ;. - розглянути можливості практичної реалізації розробленого алгоритму.<br>The topic of master thesis is “Algorithms for correlation-extreme tracking of an unmanned aerial vehicle based on video data”. The research work consists of 8 paragraphs, 83 pages, 60 illustrations and 20 tables. In total, 11 references links were used. Nowadays, the progressive development of pilot and unmanned aerial vehicles, air and ground control systems, creates a need to develop technologies that detect and watch/tracks objects. They are most widely used in navigation, space monitoring, security, on-board systems installed in aircraft, helicopters and cars, and security services. The need for detection and tracking methods is growing due to the expansion of the scope of UAVs using and as a result the exceeding of the limits which are allowed. Improving the efficiency of optoelectronic systems is necessary for the tasks of protection and defense of closed areas from unauthorized intrusion, ensuring their privacy from unmanned aerial vehicles. Modern UAVs can have not only small size and high autonomy but also extremely high maneuverability. As a result, the requirements of systems that process the set goals are constantly increasing, and therefore it leads to the improvement of existing technologies and the development of new methods and algorithms for solving these aims. The research work considers the development and analysis of an algorithm for correlation-extreme tracking of an unmanned aerial vehicle based on video data. The aim of the work is to improve the characteristics of tracking UAVs by video system surveillance, by developing a correlation-extreme tracking algorithm. The research object is the process of monitoring UAVs by the video surveillance system. The research subject is the methods of tracking UAVs by the video surveillance system. To achieve these goals have been resolved following tasks: - to analyze modern television video surveillance systems; - to analyze correlation-extreme methods of image comparison; - to consider the possibility of applying the method of Kalman filtering for UAVs tracking; - to develop an algorithm for correlation-extreme tracking of an unmanned aerial vehicle based on video data; - to evaluate the effectiveness of the developed algorithm using static simulation on a computer; - to consider the possibilities of practical implementation of the developed algorithm.<br>Магистерская работа на тему «Алгоритм корреляционно-экстремального слежения за беспилотным летательным аппаратом по данным видеонаблюдения» состоит из 8 разделов, 83 страницы, 1 приложения, 60 иллюстраций по тексту работы и 20 таблиц. Использовано 11 ссылок. На сегодняшний день прогрессивное развитие пилотной и беспилотной авиации, систем управлением воздушными и наземными объектами передвижения, создает необходимость в разработке технологий, обнаружения и сопровождающие объектов в пространстве. Наиболее широкое применение они нашли в задачах навигации, космического мониторинга Земли, обеспечения безопасности, охранных услуг, бортовых систем, устанавливаемых в самолетах, вертолетах и автомобилях. Необходимость в использовании методов обнаружения и сопровождения растет в связи с расширением области применения БПЛА, которые могут быть объектами-правонарушителями. Повышение эффективности оптико-электронных систем необходимо для задач охраны и защиты закрытых территорий от несакционованого проникновения, обеспечение их конфиденциальности от беспилотных летательных аппаратов. Современные БПЛА могут иметь не только маленькие размеры и высокую автономность, но и чрезвычайно высокую маневренность. Как следствие, постоянно повышается требования к системам, обрабатывающих поставленные цели, а потому это приводит к улучшению уже существующих технологий и разработки новых методов и алгоритмов для решения поставленных задач. В работе рассмотрена разработка и анализ алгоритма корреляционно-экстремального слежения за беспилотным летательным аппаратом по данным видеонаблюдения. Целью исследования является улучшение характеристик слежения за малоразмерными БПЛА системой видеонаблюдения, путем разработки корреляционно-экстремального алгоритма слежения. Объект исследования - процесс слежения за малоразмерными БПЛА системой видеонаблюдения. Предмет исследования - методы слежения за малоразмерными БПЛА по данным видеонаблюдения. Для достижения поставленной цели необходимо решить следующие задачи: - провести анализ современных телевизионных систем видеонаблюдения; - выполнить анализ корреляционно-экстремальных методов сопоставления изображений; - рассмотреть возможности применения метода калмановской фильтрации для слежения за точечными целями; - разработать алгоритм корреляционно-экстремального слежения за малоразмерным БПЛА на основе метода калмановской фильтрации; - оценить эффективность разработанного алгоритма с помощью статического моделирования на ЭВМ ;. - рассмотреть возможности практической реализации разработанного алгоритма.

Tato práce popisuje metodu analýzy translačního pohybu užitím křížové korelace. Ukazujeme, jakým způsobem se chová funkce křížové korelace obrazů s navzájem posunutými objekty, a jak nám to umožňuje nacházet jejich vektory posunu. Pro následnou implementaci je nalezena efektivní metoda pro hledání pouze požadovaného počtu lokálních maxim funkce.

Este trabalho consiste no estudo da estrutura sedimentar da Bacia do Paraná da região de Bebedouro utilizando função do receptor, ondas de superfície e sísmica de refração. Funções do Receptor (FR) mostram a resposta da estrutura geológica abaixo de uma estação sismográfica. Para diminuir a não unicidade na inversão do traço de uma FR, foram usadas curvas de dispersão de ondas de superfície como vínculos adicionais. Ondas de superfície foram também obtidas com a correlação cruzada de ruído sísmico ambiental. Esse método passivo permite a obtenção de dispersão em períodos intermediários entre os dados de telessismos e os dados de sísmica rasa auxiliando na determinação estruturas sedimentares. Foi utilizada a inversão conjunta de FR de alta e baixa frequência, dispersão de fase e grupo de períodos menores que 2 s e dispersão de ondas Love e Rayleigh continentais (períodos entre 10 e 100 s). Na inversão conjunta, foram usados vários modelos iniciais diferentes para garantir melhor cobertura do espaço de soluções possíveis. Os resultados mostram uma camada de basalto com uma espessura entre 200 e 400 m, sob uma camada superficial de arenito de 50 a 100m. O embasamento da bacia está torno de 2.5 3.0 km. A espessura e razão Vp/Vs crustal da região foi estimada em 40.0 (1.0) km e 1.78 (0.02). Foi possível identificar zonas de baixa velocidade dentro do pacote de basalto, possivelmente relacionadas a zonas de fraturas ou camadas de basalto alterado. Estas camadas de baixa velocidade estão na parte sul, próximas à área de maior sismicidade induzida e também relativamente mais perto dos poços profundos de maior vazão. Isto corrobora com a hipótese de que a sismicidade local está associada à exploração de poços e estrutura de falhas pré -existentes.<br>A study of the seismic structure of the Paraná Basin in Bebedouro, SP, was carried out with Receiver Functions (RF). Both low frequency (with ~0.5 Hz low pass filter) and high-frequency (~10Hz) RFs were jointly inverted with surface wave dispersion curves. Surface-wave data included: long-period group velocities of Rayleigh and Love waves from continental-scale tomography in the period range 10-100 s (useful to control crustal scale structure and Moho depth), intermediate period group velocities near 1s period obtained from cross-correlation of ambient noise (useful to control sedimentary structure), phase velocities near 0.2-1.0 s obtained from local earthquakes, and phase velocities of Rayleigh waves from shallow seismic refraction data near ~0.1 s period (useful to control shallow layers). Joint inversion was obtained with several different initial models to better cover all possible solutions. The results indicate that the basalt layer is 200 to 400m thick, beneath sandstones of about 50 100m thick. The Basin basement was detected between 2.5 3.0 km depth, consistent with expected values from regional bore-hole data in the Paraná Basin. Beneath several stations a low-velocity zone was detected in the middle of the basalt pack which is interpreted as a zone of fractured or altered basalt. This anomalous low-velocity layer was detected near the most seismically active zone in the Andes district. It is also relatively close to the deep wells with larger outflow. The existence of this low-velocity zone in the middle of the basalt layer is consistent with the model proposed for the water-well induced seismicity.

Doutoramento em Matemática Aplicada à Economia e Gestão<br>Tradicionalmente, a identificação de um modelo de função transferência bivariado é realizada através da função de correlação cruzada amostral entre as séries temporais input e output. No entanto, a prática tem mostrado que aquela função, como instrumento de identificação, apresenta um apreciável grau de subjectividade na especificação das ordens r e s, associadas aos polinómios output e input, respectivamente. Com base no estabelecimento de estimadores dos mínimos quadrados iterados consistentes, é introduzida uma generalização do conceito de função de autocorrelação estendida amostral e é proposta uma metodologia de identificação dos modelos de função transferência bivariados. Um exemplo prático e um estudo de simulação são apresentados, ilustrando as potencialidades do procedimento proposto.

Traditional naval vessels with steel structures have the benefit of large safety factors and a distinct material endurance limit. However, as performance requirements and budget constraints rise, the demand for lighter weight vessels increases. Reducing the mass of vessels is commonly achieved by the use of aluminum or composite structures, which requires closer attention to be paid to crack initiation and propagation. It is rarely feasible to require a lengthy inspection process that removes the vessel from service for an extended amount of time. Structural health monitoring (SHM), involving continuous measurement of the structural response to an energy source, has been proposed as a step towards condition-based maintenance. Furthermore, using a passive monitoring system with an array of sensors has several advantages: monitoring can take place in real-time using only ambient noise vibrations and neither deployment of an active source nor visual access to the inspected areas are required. Passive SHM on a naval vessel is not without challenge. The structures of ships are typically geometrically complex, causing scattering, multiple reflections, and mode conversion of the propagating waves in the vessel. And rather than a distinct and predictable input produced by controlled active sources, the vibration sources are hull impacts, smaller waves, and even onboard machinery and activity. This research summarizes findings from data collected onboard a Navy vessel and presents recommendations data processing techniques. The intent is to present a robust method of passive structural health monitoring for such a vessel using only ambient vibrations recordings.

Genomic and proteomic analyses have attracted a great deal of interests in biological research in recent years. Many methods have been applied to discover useful information contained in the enormous databases of genomic sequences and amino acid sequences. The results of these investigations inspire further research in biological fields in return. These biological sequences, which may be considered as multiscale sequences, have some specific features which need further efforts to characterise using more refined methods. This project aims to study some of these biological challenges with multiscale analysis methods and stochastic modelling approach. The first part of the thesis aims to cluster some unknown proteins, and classify their families as well as their structural classes. A development in proteomic analysis is concerned with the determination of protein functions. The first step in this development is to classify proteins and predict their families. This motives us to study some unknown proteins from specific families, and to cluster them into families and structural classes. We select a large number of proteins from the same families or superfamilies, and link them to simulate some unknown large proteins from these families. We use multifractal analysis and the wavelet method to capture the characteristics of these linked proteins. The simulation results show that the method is valid for the classification of large proteins. The second part of the thesis aims to explore the relationship of proteins based on a layered comparison with their components. Many methods are based on homology of proteins because the resemblance at the protein sequence level normally indicates the similarity of functions and structures. However, some proteins may have similar functions with low sequential identity. We consider protein sequences at detail level to investigate the problem of comparison of proteins. The comparison is based on the empirical mode decomposition (EMD), and protein sequences are detected with the intrinsic mode functions. A measure of similarity is introduced with a new cross-correlation formula. The similarity results show that the EMD is useful for detection of functional relationships of proteins. The third part of the thesis aims to investigate the transcriptional regulatory network of yeast cell cycle via stochastic differential equations. As the investigation of genome-wide gene expressions has become a focus in genomic analysis, researchers have tried to understand the mechanisms of the yeast genome for many years. How cells control gene expressions still needs further investigation. We use a stochastic differential equation to model the expression profile of a target gene. We modify the model with a Gaussian membership function. For each target gene, a transcriptional rate is obtained, and the estimated transcriptional rate is also calculated with the information from five possible transcriptional regulators. Some regulators of these target genes are verified with the related references. With these results, we construct a transcriptional regulatory network for the genes from the yeast Saccharomyces cerevisiae. The construction of transcriptional regulatory network is useful for detecting more mechanisms of the yeast cell cycle.

This master's thesis is focused on localization static (entering semester project) and moving acoustic sources (entering master's thesis) by the help of microphonic arrays. In the first part deal with common problems of localization. Further are here described types of microphonic arrays, simplifying possibilities which delimited this problems and general information about room acoustics. In the next part of this master's thesis are step by step mentioned methods localization of acoustic sources. In practical part were used algorithms: Steered-Beamformer-Based Locators and TDOA-Based Locators. Last part of this master's work includes results of these algorithms.

Submitted by (ana.araujo@ufrpe.br) on 2016-07-05T15:38:42Z No. of bitstreams: 1 Erinaldo Leite Batista Almeida.pdf: 3620819 bytes, checksum: b2532ef7524f47d5417d01445fec797b (MD5)<br>Made available in DSpace on 2016-07-05T15:38:42Z (GMT). No. of bitstreams: 1 Erinaldo Leite Batista Almeida.pdf: 3620819 bytes, checksum: b2532ef7524f47d5417d01445fec797b (MD5) Previous issue date: 2009-08-10<br>Financial markets are complex systems that contain large numbers of interacting units, including interactions among various units in the same market and interactions between units in different markets. Various methods of economics, statistics and econophysics have been developed to analyze financial temporal series (such as price returns, share volume, number of transactions), and serve to establish theoretical models for underlying stochastic processes. The availability of financial data on the internet and increasing computational power have enabled researchers to conduct a large number of empirical studies on financial markets. These studies have shown some universal properties: the risk function of price returns is scale invariant, with power-law behavior and similar value of exponent for different markets; the absolute values of returns (volatility) exhibit long-range power-law correlations. In this work, we use methods if econophysics to study the statistical properties of Brazilian financial markets. We analyze and compare scale properties of risk functions and correlations in temporal series of price returns of agricultural commodities and stocks of various companies traded at Bovespa. We analyze the daily prices of five commodities and twenty stocks traded in the period 2000-2008. For both commodities and stocks, the risk function of daily price returns shows powerlaw behavior with the exponent outside the Levy stable region. The values of exponents are higher for stocks than for commodities. We use Detrended Fluctuation Analysis (DFA) to study correlations in daily time series of absolute values of returns (volatility). This method was developed to quantify long range correlations in non-stationary temporal series.All analyzed series show persistent behavior, meaning that large (small) values are more likely to be followed with large (small) values. The value of the DFA exponent is higher for commodities than for stocks. We also use Detrended Cross Correlation Analysis (DCCA) to study cross-correlations between two series. The values of DCCA exponents are above 0.5 for all series, indicating the existence of long range cross-correlations. This means that each stock or commodity has long memory of its own previous values and of previous values of other stocks or commodities studied. These results are in agreement with results obtained for American financial markets.<br>Mercados financeiros são caracterizados por um grande número de unidades e interações complexas, incluindo as interações internas (entre diferentes elementos de um mercado) e fatores externos (influência de outros mercados). Vários métodos de economia, estatística e recentemente econofísica foram desenvolvidos para analisar as séries temporais de variáveis financeiras (retorno de preços de ações, mercadorias e taxas de cambio, índice de mercado, volume de negociação, etc.), com objetivo de estabelecer os modelos teóricos para processos estocásticos que estão em base desses fenômenos. A disponibilidade de dados financeiros de vários mercados e crescente poder computacional resultaram em um grande número de estudos empíricos cujos resultados mostraram algumas propriedades universais: a função risco de retornos de preços segue uma lei de potência com o valor de expoente similar para os vários mercados; os valores absolutos de retornos possuem correlações de longo alcance. Neste trabalho foram usados os métodos de econofísica para estudar as propriedades estatísticas do mercado financeiro brasileiro. Foram analisadas e comparadas as propriedades de escala de função risco e de correlações em séries temporais de retornos de preços de mercadorias agrícolas e preços de ações de várias empresas negociadas na Bolsa de Valores de São Paulo (BOVESPA). Foram analisados os preços diários de cinco mercadorias: açúcar, algodão, café, soja e boi, registrados em período 2000-2008. Para ações, analisamos as características seguintes: preços de abertura, fechamento, valores máximo e mínimo, volume e montante. Todas as séries são diárias, registradas no período de 2000-2008. São estudadas 20 empresas divididas em 4 grupos: bancos, energia, telecomunicações e siderurgia (5 empresas de cada grupo). Para todas as séries estudadas a função risco de retornos de preços segue uma lei de potência com os valores de expoente maiores para ações do que para mercadorias. As correlações são analisadas para os valores absolutos de retornos de preços (volatilidade). Foi usado o método Detrended Fluctuation Analysis (DFA), desenvolvido para quantificar as correlações de longo alcance em séries temporais não estacionárias. Todas as séries mostraram um comportamento persistente, significando que os valores grandes (pequenos) tem maior probabilidade de serem seguidos por valores grandes (pequenos). Os valores de expoente DFA são maiores para mercadorias do que para as ações. Foi utilizada uma generalização de DFA, Detrended Cross Correlation Analysis (DCCA) para analisar as correlações cruzadas entre duas séries. Os valores de expoente DCCA para todas as séries estudadas indicam a existência de correlações cruzadas de longo alcance significando que os valores de cada série possuem memória de longo alcance de seus valores anteriores e também de valores anteriores de outras série. Os resultados estão em acordo com os resultados obtidos para mercado americano.

The goal of this study is to determine the intentional movement direction based on the neural signals recorded from the motor cortex using optical brain imaging techniques. Towards this goal, we developed a cross-correlation analysis technique to determine the movement direction from the hemodynamic signals recorded from the motor cortex. Healthy human subjects were asked to perform a two-dimensional hand movement in two orthogonal directions while the hemodynamic signals were recorded from the motor cortex simultaneously with the movements. The movement directions were correlated with the hemodynamic signals to establish the cross-correlation patterns of firings among these neurons. Based on the specific cross-correlation patterns with respect to the different movement directions, we can distinguish the different intentional movement directions between front-back and right-left movements. This is based on the hypothesis that different movement directions can be determined by different cooperative firings among various groups of neurons. By identifying the different correlation patterns of brain activities with each group of neurons for each movement, we can decode the specific movement direction based on the hemodynamic signals. By developing such a computational method to decode movement direction, it can be used to control the direction of a wheelchair for paralyzed patients based on the changes in hemodynamic signals recorded using non-invasive optical imaging techniques.

Nesta pesquisa, é proposta uma metodologia para detectar e classificar os distúrbios observados em um Sistema Elétrico Industrial (SEI), além de estimar de forma não intrusiva, o torque eletromagnético e a velocidade associada ao Motor de Indução Trifásico (MIT) em análise. A metodologia proposta está baseada na utilização da Transformada Wavelet (TW) para a detecção e a localização no tempo dos afundamentos e interrupções de tensão, e na aplicação da Função Densidade de Probabilidade (FDP) e Correlação Cruzada (CC) para a classificação dos eventos. Após o processo de classificação dos eventos, a metodologia como implementada proporciona a estimação do torque eletromagnético e a velocidade do MIT por meio das tensões e correntes trifásicas via Redes Neurais Artificiais (RNAs). As simulações computacionais necessárias sobre um sistema industrial real, assim como a modelagem do MIT, foram realizadas utilizando-se do software DIgSILENT PowerFactory. Cabe adiantar que a lógica responsável pela detecção e a localização no tempo detectou corretamente 93,4% das situações avaliadas. Com relação a classificação dos distúrbios, o índice refletiu 100% de acerto das situações avaliadas. As RNAs associadas à estimação do torque eletromagnético e à velocidade no eixo do MIT apresentaram um desvio padrão máximo de 1,68 p.u. e 0,02 p.u., respectivamente.<br>This study proposes a methodology to detect and classify the disturbances observed in an Industrial Electric System (IES), in addition to, non-intrusively, estimate the electromagnetic torque and speed associated with the Three-Phase Induction Motor (TPIM) under analysis. The proposed methodology is based on the use of the Wavelet Transform WT) for the detection and location in time of voltage sags and interruptions, and on the application of the Probability Density Function (PDF) and Cross Correlation (CC) for the classification of events. After the process of events classification, the methodology, as implemented, provides the estimation of the electromagnetic torque and the TPIM speed through the three-phase voltages and currents via Artificial Neural Networks (ANN). The necessary computer simulations of a real industrial system, as well as the modeling of the TPIM, were performed by using the DIgSILENT PowerFactory software. The logic responsible for the detection and location in time correctly detected 93.4% of the assessed situations. Regarding the classification of disturbances, the index reflected 100% accuracy of the assessed situations. The ANN associated with the estimation of the electromagnetic torque and speed at the TPIM shaft showed a maximum standard deviation of 1.68 p.u. and 0.02 p.u., respectively.

Thesis (Ph.D. in Statistical Science)--S.M.U.<br>Title from PDF title page (viewed Mar. 16, 2009). Source: Dissertation Abstracts International, Volume: 69-04, Section: B, page: 2395. Adviser: William R. Schucany. Includes bibliographical references.

An approximate of the Green's function can be obtained by taking the cross-correlation of ambient noise that has been simultaneously recorded on separate sensors. This method is applied for two experiments, which illustrate the advantages and challenges of this technique. The first experiment is in the ultrasonic regime [5-30] MHz and uses capacitive micromachined ultrasonic transducer arrays to image the near field and compares the passive imaging to the conventional pulse-echo imaging. Both the array and target are immersed in a fluid with the sensors recording the fluid's random thermal-mechanical motion as the ambient noise. The second experiment is a passive ocean monitoring experiment, which uses spatiotemporal filtering to rapidly extract coherent arrivals between two vertical line arrays. In this case the ambient noise in the frequency band [250 1500] Hz is dominated by non-stationary shipping noise. For imaging purposes, the cross-correlation needs to extract the Green's function so that the imaging can be done correctly. While for monitoring purposes, the important feature is the change in arrivals, which corresponds to the environment changing. Results of both experiments are presented along with the advantages of this passive method over the more accepted active methods.

Ventrolateral medullary neurons have important roles in cardiorespiratory coordination. A rostral extension of the ventral respiratory column (RVRC), including the retrotrapezoid nucleus (RTN), has neurons responsive to local perturbations of CO2 / pH. Respiratory-modulated firing patterns of RVRC neurons are attributed to influences of more caudal (CVRC) neurons. These circuits remain poorly understood. This study addressed the hypothesis that both local interactions and influences from the CVRC shape rostral neuron discharge patterns and responses. Spike trains from 294 rostral and 490 caudal neurons were recorded with multi-electrode arrays along with phrenic nerve activity in 14 decerebrate, vagotomized cats. Overall, 214 rostral and 398 caudal neurons were respiratory-modulated; 124 and 95, respectively, were cardiac-modulated. Subsets of these neurons were evaluated for responses to sequential, selective, transient stimulation of central and peripheral chemoreceptors and arterial baroreceptors. In 5 experiments, Mayer wave-related oscillations (MWROs) in neuronal firing rates were evoked, enhanced, or reduced following central chemoreceptor stimulation. Overall, 174 of the rostral neurons (59.5%) had short- time scale correlations with other RVRC neurons. Of these, 49 triggered cross-correlograms with RVRC targets yielding 330 offset features indicative of paucisynaptic actions from a total of 2,884 rostral pairs evaluated. Forty-nine of the CVRC neurons (10.0%) were triggers in 142 CVRC-RVRC correlograms - from a total of 8,490 - with offset features indicative of actions on RVRC neurons. Correlation linkage maps support the hypothesis that local circuit mechanisms contribute to the respiratory and cardiac modulation of RVRC neurons and their responses to chemoreceptor and baroreceptor challenges.

Cílem mé diplomové práce bylo navrhnout metodu analýzy retinálních sekvencí, která bude hodnotit kvalitu jednotlivých snímků. V teoretické části se také zabývám vlastnostmi retinálních sekvencí a způsobem registrace snímků z fundus kamery. V praktické části je implementována metoda hodnocení kvality snímků, která je otestována na reálných retinálních sekvencích a vyhodnocena její úspěšnost. Práce hodnotí i vliv této metody na registraci retinálních snímků.

Dans ce travail, l'approche non-paramétrique par noyaux associés mixtes multivariés est présentée pour les fonctions de densités, de masse de probabilité et de régressions à supports partiellement ou totalement discrets et continus. Pour cela, quelques aspects essentiels des notions d'estimation par noyaux continus (dits classiques) multivariés et par noyaux associés univariés (discrets et continus) sont d'abord rappelés. Les problèmes de supports sont alors révisés ainsi qu'une résolution des effets de bords dans les cas des noyaux associés univariés. Le noyau associé multivarié est ensuite défini et une méthode de leur construction dite mode-dispersion multivarié est proposée. Il s'ensuit une illustration dans le cas continu utilisant le noyau bêta bivarié avec ou sans structure de corrélation de type Sarmanov. Les propriétés des estimateurs telles que les biais, les variances et les erreurs quadratiques moyennes sont également étudiées. Un algorithme de réduction du biais est alors proposé et illustré sur ce même noyau avec structure de corrélation. Des études par simulations et applications avec le noyau bêta bivarié avec structure de corrélation sont aussi présentées. Trois formes de matrices des fenêtres, à savoir, pleine, Scott et diagonale, y sont utilisées puis leurs performances relatives sont discutées. De plus, des noyaux associés multiples ont été efficaces dans le cadre de l'analyse discriminante. Pour cela, on a utilisé les noyaux univariés binomial, catégoriel, triangulaire discret, gamma et bêta. Par la suite, les noyaux associés avec ou sans structure de corrélation ont été étudiés dans le cadre de la régression multiple. En plus des noyaux univariés ci-dessus, les noyaux bivariés avec ou sans structure de corrélation ont été aussi pris en compte. Les études par simulations montrent l'importance et les bonnes performances du choix des noyaux associés multivariés à matrice de lissage pleine ou diagonale. Puis, les noyaux associés continus et discrets sont combinés pour définir les noyaux associés mixtes univariés. Les travaux ont aussi donné lieu à la création d'un package R pour l'estimation de fonctions univariés de densités, de masse de probabilité et de régression. Plusieurs méthodes de sélections de fenêtres optimales y sont implémentées avec une interface facile d'utilisation. Tout au long de ce travail, la sélection des matrices de lissage se fait généralement par validation croisée et parfois par les méthodes bayésiennes. Enfin, des compléments sur les constantes de normalisations des estimateurs à noyaux associés des fonctions de densité et de masse de probabilité sont présentés<br>This work is about nonparametric approach using multivariate mixed associated kernels for densities, probability mass functions and regressions estimation having supports partially or totally discrete and continuous. Some key aspects of kernel estimation using multivariate continuous (classical) and (discrete and continuous) univariate associated kernels are recalled. Problem of supports are also revised as well as a resolution of boundary effects for univariate associated kernels. The multivariate associated kernel is then defined and a construction by multivariate mode-dispersion method is provided. This leads to an illustration on the bivariate beta kernel with Sarmanov's correlation structure in continuous case. Properties of these estimators are studied, such as the bias, variances and mean squared errors. An algorithm for reducing the bias is proposed and illustrated on this bivariate beta kernel. Simulations studies and applications are then performed with bivariate beta kernel. Three types of bandwidth matrices, namely, full, Scott and diagonal are used. Furthermore, appropriated multiple associated kernels are used in a practical discriminant analysis task. These are the binomial, categorical, discrete triangular, gamma and beta. Thereafter, associated kernels with or without correlation structure are used in multiple regression. In addition to the previous univariate associated kernels, bivariate beta kernels with or without correlation structure are taken into account. Simulations studies show the performance of the choice of associated kernels with full or diagonal bandwidth matrices. Then, (discrete and continuous) associated kernels are combined to define mixed univariate associated kernels. Using the tools of unification of discrete and continuous analysis, the properties of the mixed associated kernel estimators are shown. This is followed by an R package, created in univariate case, for densities, probability mass functions and regressions estimations. Several smoothing parameter selections are implemented via an easy-to-use interface. Throughout the paper, bandwidth matrix selections are generally obtained using cross-validation and sometimes Bayesian methods. Finally, some additionnal informations on normalizing constants of associated kernel estimators are presented for densities or probability mass functions

Cette thèse vise à étudier expérimentalement, analytiquement et numériquement, les conséquences de variations et d'oscillations hydrodynamiques à forte variabilité temporelle en milieux poreux partiellement saturés. Les problèmes que nous étudions comportent des surfaces libres tant à l'extérieur qu'à l'intérieur des milieux poreux, celles-ci étant définies comme des isosurfaces de pression d'eau égale à la pression atmosphérique (Pwater = Patm). Les différentes études expérimentales réalisées en laboratoire sont, respectivement : une expérience d'imbibition dans une boite à sable avec effets capillaires importants; la transmission d'oscillations de la surface libre à travers un massif sableux intercalaire dans un petit canal à houle (IMFT, Toulouse); l'étude de la dynamique et de la propagation des oscillations des niveaux d'eau dans un grand canal à houle (HYDRALAB, Barcelone), partiellement recouvert d'un fond sableux incliné, avec mesures de niveaux d'eau en pleine eau et sous le sable, et mesures du fond sableux (érosion/dépôts). Pour les études théoriques, nous avons développés des solutions analytiques linéarisées. Un exemple de problème traité analytiquement est: l'équation linéarisée de Dupuit-Boussinesq (D-B) transitoire à surface libre, en hypothèse d'écoulements plans et vidange/remplissage instantané : oscillations forcées, transmission et dissipation d'ondes à travers une boite à sable rectangulaire. Nous avons aussi développé une solution de l'équation faiblement non linéaire de Dupuit- Boussinesq (D-B) pour étudier le problème d'imbibition avec variation abrupte du niveau d'eau amont (suivi temporel du front de saturation). Nous avons pu étudier les différents types de problèmes transitoires liés aux expériences citées plus haut par simulation numérique. En particulier, nous avons simulé des écoulements partiellement saturés et insaturés, en coupe verticale, à l'aide d'un code de calcul (BIGFLOW 3D) qui résoud l'équation de Richards généralisée en régime transitoire. Nous avons ainsi étudié numériquement en régime non saturé, l'expérience d'imbibition dans un sable initialement sec à frontières verticales (IMFT sandbox), puis l'expérience de propagation d'ondes dans le grand canal à houle de Barcelone (laboratoire HYDRALAB) comportant une plage de sable inclinée, avec un couplage complètement intégré entre les zones micro-poreuse (sable) et “macro-poreuse” (pleine eau). Pour analyser les résultats de cette dernière expérience et les comparer aux simulations, nous avons utilisé plusieurs méthodes de traitement et d'analyse des signaux : analyse de Fourier (spectres de fréquences) ; ondelettes discrètes multi-résolution (Daubechies) ; analyses corrélatoires simple et croisée. Ces méthodes sont combinées avec des méthodes de préfiltrage pour estimer dérives et résidus (moyennes mobiles ; ondelettes multi-résolution). Cette analyse des signaux a permis de comprendre et quantifier la propagation à travers une plage de sable. Au total, les différentes approches de modélisation mis en oeuvre, associé à des procédures de calage en situation de couplage transitoire non linéaire ont permis de reproduire globalement les phénomènes de propagation de teneur en eau et de niveau d'eau dans les différentes configurations étudiées<br>This thesis aims at investigating experimentally, analytically and numerically, the consequences of hydrodynamic variations and oscillations with high temporal variability in partially saturated porous media. The problems investigated in this work involve “free surfaces” both outside and inside the porous media, the free surface being defined as the “atmospheric” water pressure isosurface (Pwater = Patm). The laboratory experiments studied in this work are, respectively: Lateral imbibition in a dry sand box with significant capillary effects; Transmission of oscillations of the free surface through a vertical sand box placed in a small wave canal (IMFT, Toulouse); Dynamics of free surface oscillations and wave propagation in a large wave canal (HYDRALAB, Barcelona), partially covered with sand, with measurements of both open water and groundwater levels, and of sand topography (erosion / deposition). For theoretical studies, we have developed linearized analytical solutions. Here is a sample problem that was treated analytically in this work: The linearized equation of Dupuit-Boussinesq (DB) for transient free surface flow, assuming horizontal flow and instantaneous wetting/drainage of the unsaturated zone: forced oscillations, wave transmission and dissipation through a rectangular sandbox. We also developed a weakly nonlinear solution of the Dupuit-Boussinesq equation to study the sudden imbibition (temporal monitoring of the wetting front). We have studied the different types of transient flow problems related to the experiments cited above by numerical simulation. In particular, we have simulated unsaturated or partially saturated transient flows in vertical cross-section, using a computer code (BIGFLOW 3D) which solves a generalized version of Richards’ equation. Thus, using the Richards / BIGFLOW 3D model, we have studied numerically the experiment of unsaturated imbibition in a dry sand (IMFT sandbox), and then, with the same model, we have also studied the partially saturated wave propagation experiment in the large Barcelona wave canal (HYDRALAB laboratory), focusing on the sloping sandy beach, with coupling between the micro-porous zone (sand) and the “macro-porous” zone (open water). To interpret the results of the latter experiment and compare them to simulations, we use several methods of signal analyzis and signal processing, such as: Fourier analysis, discrete multi-resolution wavelets (Daubechies), auto and cross-correlation functions. These methods are combined with pre-filtering methods to estimate trends and residuals (moving averages; discrete wavelet analyses). This signal analyzis has allowed us to interpret and quantify water propagation phenomena through a sandy beach. To sum up, different modeling approaches, combined with model calibration procedures, were applied to transient nonlinear coupled flow problems. These approaches have allowed us to reproduce globally the water content distributions and water level propagation in the different configurations studied in this work

碩士<br>逢甲大學<br>土木及水利工程所<br>92<br>The main purpose of this thesis is to establish a stress-wave velocity measuring system for standard cylindrical specimens in the laboratory for research in the future. The size of the specimen is 15cm in diameter and 30cm in height. Two kinds of materials have been tested including steel and concrete. The stress-wave is generated upon the bottom plane of the specimen by a steel ball and received by two vertical accelerometers which are located on the orthogonal side of the impact plane. The cross-correlation velocity is determined by cross-correlation function in time domain. In order to verify the correctness of the cross-correlation velocity obtained in this research, a ultrasonic thickness gage was used to measure the wave velocity of the steel specimen whereas a impact-echo system was used for the concrete specimen. According to the experimental results, the testing arrangement parameters were suggested: the vertical distance of the impact Iy＝0.7cm, horizontal distance of the impact r=11cm, and distance between two receivers d=9cm. Also, the average value of four base lines from the specimen was suggested to represent the wave velocity of the specimen. Based on the arrangement parameters suggested aforementioned, the average of four lines to represent the velocity of the specimen. The average cross-correlation velocity of concrete cylinder is 3455 m/s, coefficient of variation is 1.975m/s. and the absolute error with impact-echo velocity is 0.8267％.

博士<br>國立臺灣大學<br>海洋研究所<br>103<br>Retrieving the Empirical Greens function (EGF) between two receivers by cross-correlating continuous records is now a well-recognized technique and the derived EGFs have been applied to various fields of seismology. However, little attention has been given to a more quantitative description on the noise behavior of the noise-derived cross-correlation functions (CCF), for its signal-to-noise ratio (SNR) can be improved easily by increasing the total correlation time. In this thesis, we propose a method to measure the noises within the CCFs and demonstrate the relationship between noises and the corresponding sources properties. We evaluate the original noise level (ONL) for CCFs in Taiwan and Korea. With the measured ONL, we can estimate data quality for any portion of the CCF in the time domain. Moreover, since the ONL is closely related to the noise source population and EGF’s amplitude is sensitive to the excitation strength, combination of both measurements allows us to put better constraints to the noise sources. Using the approach, we conclude that (1) The dominant microseisms of period 5~10 sec observed in Taiwan and Korea are mostly contributed by Primary microseisms (PM), rather than long period secondary microseisms (LPSM) proposed by previous studies; (2) The high short period secondary microseisms (SPSM) level in Taiwan Strait is mainly caused by the bathymetry effect; (3) The low ONL in the SPSM band implies that sources for these dominant signals in CCFs are likely confined in the near-coast region; (4) The expected high source population of PM around Taiwan is well demonstrated by the strong ONL in the period ~6-9 seconds, although the PM signals are not present in the CCF records or the background seismic noises.

碩士<br>國立陽明大學<br>放射醫學科學研究所<br>94<br>In signal process, the cross correlation is a measure of similarity of two signals. It is commonly used to find features in an unknown signal by comparing to a known one. It is a function of the relative time between the two signals. In the perfusion brain MRI, we can observe similar concentration-time curves with time lag in different tissues through the calculation of cross correlation, we take the concentration-time curve in an artery region as a known signal, to compare the time lag of the concentration-time curves in different tissues. Furthermore, we want to distinguish the normal tissue, stenosis, and infarction lesion in the perfusion brain MRI of patient. Through this study, we can find the parameters of , ,(when time lag is zero) and by cross correlation function. We can clearly distinguish the difference between normal volunteer and patient with stroke by parametric analysis.

碩士<br>逢甲大學<br>土木工程所<br>97<br>In civil engineering, many geotechnical structures can be considered as a layered structure system. It is important to be in control of information such as the thickness and material properties in design stage, construction stage, and maintenance & management stage. Therefore, establishment of a comprehensive testing system will help to effectively construct and facilitate a geotechnical layered stratum so that not only the engineering costs as well as construction period can be cut down but also disaster loss can be effectively reduced. The purpose of this thesis was to explore the advantages and disadvantages of the Cross-Correlation Function Method (CCF) and the Spectral Analysis of Surface Waves method (SASW) through a seires of in-situ tests, to combine the advantages of these two methods, and to develop an integrated testing system in order to determine both the P-wave and R-wave velocities. Due to its simple geometry, rigid pavement was selected as the subject of this study. There are three reseach stages of this study: the first equipment development, the second equipment calibration, the third in-situ experiments which include a concrete experiment, a floor experiment, an airfield rigid pavement experiment. The research results showed that: the first arrivals of horizontally polarized receiver signals can not be easily identified, vertically polarized receiver setup will be beneficiall; vaseline can be applied to the surface of rigid pavement to improve the signal quality; filtering can enhance the quality of R-wave velocity for both the CCF and SASW methods; both CCF method and SASW method can be integrated together to determine the wave velocities of the concrete sample; surface wave velocity can be obtained by setting the lowest cutting frequency as 20kHz in the floor experiment; in airport rigid pavement experiment, weak signals were resulted from surface roughness of the pavement, signal improvement can be achieved by ground flushing; the energy of Impact Eech hammer as source is ineligible, 7.2mm steel ball can be used instead; P-wave signals of CCF are not readily measured; R-wave velocity of CCF did not significantly improved after filtering when tested on the crack in the concrete slab,; R-wave velocity of CCF can be improved after filtering for tests near the lateral boundary of the plate; difficulty exists in the SASW method to determine of R-wave velocity even after filtering; the R-wave velocity from the SASW method will not be affected by the lateral boundaries when the measurement be conducted at a distance of more than 3cm.

碩士<br>朝陽大學<br>建築及都市設計研究所碩士班<br>88<br>ABSTRACT The subjective evaluation of the spaciousness of an original sound source to the human ear is known as Apparent Source Width, ASW. This evaluation incurs the stereophonic of the spatial impression to the human, and is known as subjective diffusion. The relationship between ASW and the magnitude of the Interaural Cross-Correlation, IACC, is explained in physics as the width of the Interaural Cross-Correlation Function, WIACC. In a natural sound field, as in the performance of opera or a classical orchestra, it is important for the audience to determine the direction of the sound source. It is the visual interactive in which audiences observably and immediately respond to a performance. In addition, in establishing suitable safety arrangements it is particularly helpful when visual aids can be used for determine the direction of an escape path correlating with the source of an announcement or warning siren. The aim of this study is to explore the relationship of Source Directional Sensitivity, SDS, and Personal Binaural Spatial Impression, and whether it has the same interrelation with ASW. As a focus to the SDS topic, the research methods will use two reflections in a simulated sound field, and include not only mathematical analysis but also an investigation of the psychological feelings of a human being. The Paired Comparison and Constancy Graphical approaches for statistical analysis will be used for the psychological experiment. It is intend to quantify the results via a control on the various variables. The results of this experiment it is hoped will reveal that the change of SDS is mainly limited by IACC according to the amount of the frequency of the whole reflection, and in which IACC is related to the direction and the frequency of the arrived reflection. Thereby giving evidence of the proportional relationship between SDS and IACC. Keywords：apparent source width (ASW)、interaural cross-correlation (IACC)、 source directional sensitivity (SDS)

Nell'analisi di routine di segnali sismici registrati sia da reti fisse sia temporanee è abbastanza comune riconoscere, alle varie stazioni, coppie (doublets) o gruppi (multiplets) di eventi sismici caratterizzati da forme d'onda molto simili. Tali eventi se localizzati in corrispondenza di una ristretta fascia geografica costituiscono, se caratterizzati da comune meccanismo sorgente, quelle che vengono definite “famiglie sismogenetiche” (Tsujiura, 1983). Il riconoscimento di terremoti caratterizzati (se registrati ad una comune stazione) da sismogrammi molto simili consente indagini di dettaglio in grado di fornire informazioni molto più accurate rispetto ad una semplice localizzazione di routine; determinare una relazione diretta tra famiglie sismogenetiche e strutture geologiche presenti in una determinata area consente infatti di discriminare all’interno della stessa la presenza di sorgenti potenzialmente attive. In particolare, uno studio prolungato nel tempo dell’occorrenza di terremoti aventi le caratteristiche sopra riportate rappresenta lo strumento fondamentale al fine della determinazione dei periodi di riattivazione delle sorgenti individuate. L’analisi di somiglianza di forme d’onda può essere implementata sia nel dominio del tempo sia nel dominio delle frequenze, utilizzando a seconda dei casi tecniche basate rispettivamente sulle funzioni di cross correlazione e di cross spettro. In caso di analisi nel dominio delle frequenze i segnali analizzati sono ottenuti a partire da sismogrammi convertiti in spettri tramite l’utilizzo della funzione trasformata di Fourier. A causa del non sempre soddisfacente rapporto segnale disturbo caratterizzante le registrazioni fornite dalle reti sismiche fisse RSNI (Rete Sismica Italia Nord Occidentale) ed RSLG (Rete sismica Lunigiana-Garfagnana), gestite direttamente dalla sezione geofisica dell’Università di Genova ed utilizzate come base di partenza per gli studi effettuati, nel presente lavoro di tesi sono state implementate tecniche di analisi del segnale sismico esclusivamente nel dominio del tempo. Al fine di determinare in termini oggettivi un adeguato settaggio per tutti i parametri coinvolti in un’analisi di somiglianza di forme d’onda si è compiuto uno studio di dettaglio considerando come test la sismicità dell’Appennino Settentrionale (area Lunigiana- Garfagnana) registrata dalla rete fissa RSLG nel periodo 1999 - 2003. In base alle risultanze derivate da una preliminare analisi del rapporto segnale disturbo effettuata a ciascuna stazione della rete RSLG, è stato selezionato un data set composto da circa 1.000 terremoti, aventi magnitudo locale compresa tra 1.5 e 4.1. L’analisi delle forme d'onda è stata implementata nel dominio del tempo utilizzando la funzione di cross correlazione normalizzata. A differenza di recenti studi su doublets sismici, per ogni singolo sismogramma è stata analizzata una finestra temporale comprendente tutte le fasi del segnale considerato. Molteplici test eseguiti hanno infatti dimostrato come effettuare un’analisi di somiglianza considerando ridotte porzioni di sismogramma (pochi secondi) conduca in modo inequivocabile alla determinazione di famiglie sismogenetiche erroneamente sovradimensionate. Come sottolineato in Ferretti et al., 2005 (accettato in via preliminare per la pubblicazione sulla rivista “Bulletin Seismological Society of America”) l’indice di cross-correlazione calcolato considerando un’adeguata finestra temporale, comprendente fase P, fase S e parte della coda, consente di ottenere valori di similitudine dipendenti anche da componenti di segnale strettamente legate alla propagazione nel mezzo. Una volta ottenuti affidabili indici di somiglianza si è proceduto alla determinazione, a partire da coppie di terremoti simili (doublets), di una soglia minima di cross correlazione (indice di somiglianza) riferita a ciascuna stazione utilizzata, da applicare al fine di discriminare quelle che vengono definite famiglie sismogenetiche (multiplets). A tale scopo è stata applicata una innovativa procedura (Ferretti et al., 2005) in grado di considerare sia le componenti verticali sia le componenti orizzontali dei segnali registrati a tutte le stazioni della rete sismica considerata. Il raggruppamento in famiglie è stato effettuato utilizzando la “bridging technique” (Aster and Scott, 1993), considerandone vantaggi e svantaggi rispetto alle metodologie classiche. Il risultato finale è stata la determinazione di 27 multiplets, ognuno dei quali riconosciuto da più stazioni con valori minimi di somiglianza superiori all’ 80%. Considerando le famiglie sismogenetiche maggiormente significative (in termini di componenti) e contemporaneamente localizzate internamente alla rete RSLG, è stata applicata a ciascuna di esse una procedura di localizzazione in relativo tramite l’utilizzo del “double difference algorithm” (Waldhauser and Ellsworth, 2000). L’accuratezza dei parametri ipocentrali ottenuta tramite la procedura di ri-localizzazione è stata testata analizzando due differenti data set, composti rispettivamente da eventi localizzati internamente ed esternamente alla rete RSLG. I risultati ottenuti hanno messo in evidenza la buona affidabilità del metodo per eventi sismici localizzati internamente al network ed allo stesso tempo una scarsa significatività dei risultati considerando un data set caratterizzato al contrario da eventi sismici caratterizzati da elevato gap azimutale e non trascurabile distanza ipocentro-prima stazione. Per ciascuna famiglia rilocalizzata è stato calcolato, ove possibile, il meccanismo focale cumulato al fine di determinare l’orientazione del piano di faglia principale. Una successiva applicazione delle metodologie sopra descritte è stata effettuata utilizzando come data set di partenza circa 250 terremoti, registrati dalla rete sismica RSNI nel periodo Agosto 2000 - Luglio 2001, localizzati in una ristretta area geografica ubicata pochi km a NO di Acqui Terme (Monferrato, Piemonte) (Massa et al., 2005, accettato in via preliminare per la pubblicazione sulla rivista “Journal of Seismology”). L’analisi di doublets unita ad una successiva procedura di localizzazione in relativo ha condotto alla determinazione di 5 multiplets, ognuno dei quali aventi parametri di localizzazione caratterizzati, se paragonati ai medesimi derivati dalla localizzazione di bollettino, da un brusco decremento degli errori. Le nuove localizzazioni delle famiglie sismogenetiche, nonostante abbiano consentito di definire per l’area in studio una distribuzione di sismicità interpretabile in riferimento alle conoscenze concernenti l’assetto geologico strutturale dell’area stessa, rimangono in questo caso affette, per quanto riguarda le coordinate assolute, da non trascurabili errori insiti nelle localizzazioni di partenza. La configurazione del network a disposizione, sia in termini di gap azimutale sia in termini di distanza epicentri-stazione, non ha consentito, relativamente alla posizione dell’area epicentrale, di ottenere affidabili localizzazioni assolute. Il confronto dei risultati derivanti dall’applicazione di medesime metodologie, a partire da differenti condizioni al contorno, ha consentito di definire le condizioni limite di applicabilità delle stesse, le quali se utilizzate senza alcun criterio di selezione condurranno in generale ad un mancato miglioramento delle condizioni di partenza e/o a risultati erronei. La parte conclusiva degli studi trattati è stata dedicata allo sviluppo di un nuovo algoritmo di localizzazione assoluta basato esclusivamente su un’analisi di somiglianza di forme d’onda effettuata ad una singola stazione di riferimento (Massa et. al. 2005, sottomesso alla rivista “Journal of Geophysical Research”). Tale procedura è stata implementata considerando come riferimento la stazione mono-componente di Sant’Anna di Valdieri (rete sismica RSNI), ubicata nelle Alpi Sud Occidentali, in prossimità del confine italo-francese. Sono stati raccolti in un data base di partenza, accuratamente selezionato a seguito di un’analisi del rapporto segnale disturbo, circa 2.700 sismogrammi verticali, registrati in un’area di 40 km x 40 km nel periodo 1985-2004. L’analisi di somiglianza, precedentemente descritta è stata in grado di discriminare per il periodo considerato 80 multiplets, a ciascuno dei quali è stato possibile associare un evento master (evento di riferimento) in corrispondenza del quale fare collassare le coordinate ipocentrali di tutti gli eventi appartenenti alla famiglia associata al medesimo. Utilizzando il data set di multiplets ricavato per il periodo in esame, l’algoritmo di localizzazione è stato testato utilizzando un data set ridotto composto da circa 100 terremoti, registrati nell’area in studio nel periodo Gennaio 2003 - Giugno 2004. Tramite la suddetta metodologia di localizzazione, basata esclusivamente sui risultati derivati da un’analisi di forme d’onda nel dominio del tempo, è stato possibile localizzare circa il 50% degli eventi appartenenti al data set ridotto. Il vantaggio principale di tale procedura, rispetto alle tecniche usualmente utilizzate per determinare le coordinate ipocentrali di eventi sismici, risulta l’indipendenza della medesima da errori derivanti da sfavorevoli geometre di rete rispetto all’area epicentrale, dal numero di stazioni (fasi registrate), dalla distanza ipocentro-prima stazione e da errori di lettura delle fasi sismiche da parte di un operatore. L’attenzione rivolta allo studio delle sequenze sismiche, con la conseguente possibilità di dare una corretta caratterizzazione alle strutture sismogenetiche presenti nelle aree considerate, rappresenta uno passo fondamentale per qualsiasi tipo di studio disciplinare successivo; la qualità dei risultati ottenibili attraverso la costruzione di modelli tomografici e di propagazione (sulla base dei quali vengono effettuati gli studi di rischio sismico) dipende infatti dagli errori ottenuti durante le procedure di localizzazione dei terremoti e di conseguenza dalla corretta individuazione delle strutture sismogenetiche responsabili degli stessi.<br>Istituto Nazionale di Geofisica e Vulcanologia, sezione di Milano-Pavia<br>Unpublished<br>3.1. Fisica dei terremoti<br>open