Phase-extraction from fringe patterns is an inevitable procedure in the field of optical metrology and interferometry. However, speckle noise will introduce and influence the precision of wrapped phase map when a coherent light is used. In this thesis, we use the bidimensional empirical mode decomposition (BEMD) to perform the speckle-reduction. Moreover, different interpolation method in BEMD will be used to compare their performance in speckle-reduction. Finally, the database will be developed to make the BEMD a robotic tool to reduce noises. And the database also points out that the performance of BEMD is highly related to the fringe period, the fringe visibility, and the SNR of speckle noise.

Internal waves occur in the interface between two layers of fluids with density stratification. In order to better understand the characteristics of continuous internal waves, a series of experiments were conducted in a laboratory tank. The upper and lower layers are fresh water of 15 cm thick and salt water of 30 cm thick, respectively. The periods of internal waves are 2.5, 5.5 and 6.6 sec. A micro-ADV is used to measure velocity profiles. Wave profiles at the density interface and the free surface are monitored respectively by an ultrasonic and capacitance wave gauges. Our results indicate that particle velocities (u and w) above and below the density interface have opposite directions. The speed is peaked near the density interface and it becomes weaker further away from the interface. Empirical Mode Decomposition is used to remove noise from the observed particle velocities, and the period is consistent with those derived from the interface elevations. The observed particle velocities also compare favorably with the theoretical results. When internal waves propagate without the interference of a sloping bottom, the turbulence induced is rather insignificant. The turbulence is more significant only near the density interface. With the existence of a sloping bottom, the internal waves gradually shoal and deform, the crest becomes sharp and steep, finally the waves become unstable, break and overturn. In this study the effect of bottom slope and the steepness of internal waves on the reflectivity of incoming waves are investigated. The reflectivity is smaller with gentler slope, and it increases and reaches a constant value with steeper slopes. The observed energy dissipation rate£`is higher near the slope. Three methods were used to estimate the energy dissipation rate and shear stress; namely, the inertial dissipation, the TKE and auto-correlation method. The£` estimated from the auto-correlation method is larger than that from the other two methods, but their trend is similar. The energy dissipation rate is found to increase with a gentler sloping bottom.

Nan Wan is a half-closed embayment in the most southern part of Taiwan. While facing the Luzon Strait, it also connects to the Pacific Ocean in its southeast, and is adjacent the Taiwan Strait and the South China Sea . In view of general oceanic circulation, Nan Wan Bay happens to lie to the rim of South China Sea circumfluence and Kuroshio where a variety of water mass exchange has taken place, causing saline intrusion and mixed of water. Seasonal variation and tidal fluctuations also contribute to the exchange of water masses. The Third Nuclear Power Station of Taiwan Power Company is located in Nan Wan with its thermal discharge outlet adjacent to Maobitou to the west of the bay in order to minimize the effect of warm water discharge on the local marine ecology and coral . A long-term monitoring program on water temperature and other environmental factors has been set up implemented .this research report will first describe the archives regarding the hydrology in Nan Wan in support of monitoring the process in temperature variation . Previous research efforts are found somehow unable reveal precisely the physical mechanism leading to water temperature variations in the bay, due to limited facilities, short of information or poor analytical tools. This report adopts 14 records of water temperature at the thermal outlet of the Third Nuclear Power Station for signal analysis. As to non-linear and unstable data analysis, it is based on the Hilbert-Huang Transform. HHT includes Empirical Mode Decomposition, EMD which could decompose the raw data into numerous Intrinsic Mode Function, IMF. It is allowed to comprehend the main causes for the rising and dropping of water temperature based on the variation of spectroscopy by transferring through Hilbert and analyzing via IMF. Furthermore, the characteristic of each quantity could be developed according to the quantities acquired from the former method of HHT. The analytical report of water temperature covers 14 records dating from 1999 to 2003. In light of the analytical report, tide and wind account for the main cause of the temperature variation in waters while demanding information to ensure whether it is influenced by other factors like internal waves, water masses or landforms, etc. In addition, the report compares the difference in the same of data between FFT and HHT and moreover concludes the advantages and disadvantages as reference for researches.

The early detection of damage of in-service structural or mechanical systems is of vital importance. With early detection, the damage may be repaired before the integrity of the system is jeopardized, avoiding possible monetary losses, environmental impacts, injury and death. With this goal in mind, many structural health monitoring techniques have been developed which use a combination of sensors and algorithms to collect, process and interpret data to detect damage in a structure. This thesis presents work completed in support of the experimental validation of a novel structural health monitoring technique developed with the aim of providing improved qualitative results compared to those methods currently available.

Filtering is a key step in digital image processing and analysis. It is mainly used for amplification or attenuation of some frequencies depending on the nature of the application. Filtering can either be performed in the spatial domain or in a transformed domain. The selection of the filtering method, filtering domain, and the filter parameters are often driven by the properties of the underlying image. This thesis presents three different kinds of biomedical image filtering applications, where the filter parameters are automatically determined from the underlying images. Filtering can be used for image enhancement. We present a robust image dependent filtering method for intensity inhomogeneity correction of biomedical images. In the presented filtering method, the filter parameters are automatically determined from the grey-weighted distance transform of the magnitude spectrum. An evaluation shows that the filter provides an accurate estimate of intensity inhomogeneity. Filtering can also be used for analysis. The thesis presents a filtering method for heart localization and robust signal detection from video recordings of rat embryos. It presents a strategy to decouple motion artifacts produced by the non-rigid embryonic boundary from the heart. The method also filters out noise and the trend term with the help of empirical mode decomposition. Again, all the filter parameters are determined automatically based on the underlying signal. Transforming the geometry of one image to fit that of another one, so called image registration, can be seen as a filtering operation of the image geometry. To assess the progression of eye disorder, registration between temporal images is often required to determine the movement and development of the blood vessels in the eye. We present a robust method for retinal image registration. The method is based on particle swarm optimization, where the swarm searches for optimal registration parameters based on the direction of its cognitive and social components. An evaluation of the proposed method shows that the method is less susceptible to becoming trapped in local minima than previous methods. With these thesis contributions, we have augmented the filter toolbox for image analysis with methods that adjust to the data at hand.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / This paper proposes a new measure of core inflation called systematic core and makes a comparative evaluation with conventional cores used by the Central Bank of Brazil. To estimate the systematic core is proposed in this paper used the method of decomposition empirical methods, which is able to separate noise data by spectral decomposition and partial reconstruction of the series of inflation. The evaluation and comparison of the cores of inflation are performed by testing econometric predictions outside the sample. The empirical results show that conventional cores used by the Central Bank does not contribute to forecast inflation out of sample and not have all the desirable statistical properties for which a nucleus. Already the new measure of core obtained in this work contributed to predict inflation out of sample and answered the statistical properties of non-biased, attractor of inflation and weakly exogenous, having therefore the characteristics required for a measure to be useful to policy objectives monetary. / Este trabalho propÃe uma nova medida de nÃcleo da inflaÃÃo denominada nÃcleo sistemÃtico e faz uma avaliaÃÃo comparativa com os nÃcleos convencionais utilizados pelo Banco Central do Brasil. Para estimar o nÃcleo sistemÃtico proposto neste trabalho à utilizado o mÃtodo de decomposiÃÃo em modos empÃricos, que à capaz de separar ruÃdo dos dados atravÃs da decomposiÃÃo espectral e reconstruÃÃo parcial da sÃrie de inflaÃÃo. A avaliaÃÃo e comparaÃÃo dos nÃcleos da inflaÃÃo sÃo realizadas por meio de testes economÃtricos e previsÃes fora da amostra. Os resultados empÃricos apontam que os nÃcleos convencionais utilizados pelo Banco Central nÃo contribuem para prever a inflaÃÃo fora da amostra e nÃo possuem todas as propriedades estatÃsticas desejÃveis que para um nÃcleo. Jà a nova medida de nÃcleo obtida neste trabalho contribuiu para prever a inflaÃÃo fora da amostra e atendeu as propriedades estatÃsticas de ausÃncia de viÃs, atrator da inflaÃÃo e fracamente exÃgeno, possuindo, portanto, as caracterÃsticas exigidas para uma medida ser Ãtil aos objetivos da polÃtica monetÃria.

High-cycle thermal fatigue arising from turbulent mixing of non-isothermal flows is a key issue associated with the life management and extension of nuclear power plants. The induced thermal loads and damage are not fully understood yet. With the aim of acquiring extensive data sets for the validation of codes modeling thermal mixing at reactor conditions, thermocouples recorded temperature time series at the inner surface of a vertical annular volume where turbulent mixing occurred. There, a stream at either 333 K or 423 K flowed upwards and mixed with two streams at 549 K. Pressure was set at 72E5 Pa. The annular volume was formed between two coaxial stainless-steel tubes. Since the thermocouples could only cover limited areas of the mixing region, the inner tube to which they were soldered was lifted, lowered, and rotated around its axis, to extend the measurement region both axially and azimuthally. Trends, which stemmed from the variation of the experimental boundary conditions over time, were subtracted from the inner-surface temperature time series collected. An estimator assessing intensity and inhomogeneity of the mixing process in the annulus was also computed. In addition, a frequency analysis of the detrended inner-surface temperature time series was performed. In the cases examined, frequencies between 0.03 Hz and 0.10 Hz were detected in the subregion where mixing inhomogeneity peaked. The uncertainty affecting such measurements was then estimated. Furthermore, a preliminary assessment of the radial heat flux at the inner surface was conducted. / <p>QC 20161116</p>

Em escalas interanuais a advecção de calor, sal e nutrientes pode afetar a produtividade primária. Pode-se citar a Circulação de Revolvimento Meridional (MOC) no impacto da concentração de clorofila. Neste estudo, a partir do método Multidimensional Empirical Mode Decomposition foram obtidos tendências decadais de PAR, nitrato integrado na coluna d\'água, concentração de clorofila e fluxo de volume da MOC. Em variações de baixa frequência há uma relação entre o transporte de volume da MOC com o nitrato integrado na coluna d\'água no Atlântico Sul, e consequentemente, na concentração de clorofila. Dois possíveis cenários foram identificados sobre o efeito da MOC no nitrato integrado e na concentração de clorofila. O cenário 1 apresenta uma relação direta no sistema MOC-nitrato integrado-concentração de clorofila, enquanto o efeito do cenário 2 é indireto, com a MOC afetando outras variáveis que perturbam o sistema. Neste estudo também foi analisado a influência de teleconexões atmosféricas na MOC do Atlântico Sul. Foi achado indícios da influência da Oscilação Antártica na MOC do Atlântico Sul em escalas decadais. Conclui-se que variações de baixa frequência no fluxo de volume da MOC alteram o padrão espaço-temporal da concentração de clorofila no Atlântico Sul. / On interannual timescales the advection of heat, salt and nutrients can affect the primary production. The influence of the Meridional Overturning Circulation (MOC) over the chlorophyll concentration can be mentioned. In this study, decadal trends of PAR, integrated nitrate over the water column, chlorophyll and volume flux of the MOC were obtained using the Multidimensional Empirical Mode Decomposition method. On low frequency variations there is a relationship between the MOC volume transport with integrated nitrate over the water column in the South Atlantic, and therefore, on chlorophyll concentration. Two scenarios were identified as possible mechanisms of influence of the MOC over integrated nitrate and chlorophyll concentrations. Scenario 1 presents a direct relationship on the system MOC-integrated nitrate-chlorophyll concentration, while scenario 2 has an indirect effect, with the MOC affecting other variables that disturb the system. In this study the influence of atmospheric teleconnections on the South Atlantic MOC were also investigated. It was found evidence that the Antarctic Oscillation can affect the South Atlantic MOC on decadal timescales. It was concluded that low frequency variability on the volume flux of the MOC can alter the spatiotemporal pattern of the chlorophyll concentration on the South Atlantic.

More than one million fetal deaths occur in the United States every year [1]. Monitoring the long-term heart rate variability provides a great amount of information about the fetal health condition which requires continuous monitoring of the fetal heart rate. All the existing technologies have either complex instrumentation or need a trained professional at all times or both. The existing technologies are proven to be impractical for continuous monitoring [2]. Hence, there is an increased interest towards noninvasive, continuous monitoring, and less expensive technologies like fetal phonocardiography. Fetal Phonocardiography (FPCG) signal is obtained by placing an acoustic transducer on the abdomen of the mother. FPCG is rich in physiological bio-signals and can continuously monitor the fetal heart rate non-invasively. Despite its high diagnostic potential, it is still not being used as the secondary point of care. There are two challenges as to why it is still being considered as the secondary point of care; in the data acquisition system and the signal processing methodologies. The challenges pertaining to data acquisition systems are but not limited to sensor placement, maternal obesity and multiple heart rates. While, the challenges in the signal processing methodologies are dynamic nature of FPCG signal, multiple known and unknown signal components and SNR of the signal. Hence, to improve the FPCG based care, challenges in FPCG signal processing methodologies have been addressed in this study. A comparative evaluation was presented on various advanced signal processing techniques to extract the bio-signals with fidelity. Advanced signal processing approaches, namely empirical mode decomposition, spectral subtraction, wavelet decomposition and adaptive filtering were used to extract the vital bio-signals. However, extracting these bio-signals with fidelity is a challenging task in the context of FPCG as all the bio signals and the unwanted artifacts overlap in both time and frequency. Additionally, the signal is corrupted by noise induced from the fetal and maternal movements as well the background and the sensor. Empirical mode decomposition algorithm was efficient to denoise and extract the maternal and fetal heart sounds in a single step. Whereas, spectral subtraction was used to denoise the signal which was later subjected to wavelet decomposition to extract the signal of interest. On the other hand, adaptive filtering was used to estimate the fetal heart sound from a noisy FPCG where maternal heart sound was the reference input. The extracted signals were validated by obtaining the frequency ranges computed by the Short Time Fourier Transform (STFT). It was observed that the bandwidths of extracted fetal heart sounds and maternal heart sounds were consistent with the existing gold standards. Furthermore, as a means of additional validation, the heart rates were calculated. Finally, the results obtained from all these methods were compared and contrasted qualitatively and quantitatively.

Στα πλαίσια της διπλωματικής αυτής εργασίας στόχος μας είναι η εφαρμογή τεχνικών ψηφιακής επεξεργασίας σήματος σε γεωφυσικά σήματα και συγκεκριμένα κατά κύριο λόγο σε σήματα γεωηλεκτρικού δυναμικού μακράς διάρκειας και σε σήματα σεισμικών κυμάτων. Έχουμε εστιάσει την επεξεργασία μας στην διερεύνηση της εφαρμογής δυο τεχνικών επεξεργασίας ξεχωριστά και σε συνδυασμό. Η πρώτη αφορά την εκτίμηση της στιγμιαίας συχνότητας ενός σήματος μέσω του τελεστή Teager-Kaiser [Maragos_1991] στοχεύοντας σε μια εναλλακτική στα προβλήματα συμβιβασμού της διακριτικής ικανότητας, στην υπολογιστική πολυπλοκότητα, στην ανίχνευση αρνητικών συχνοτήτων και στην εμφάνιση cross-terms άλλων κλασικών μεθόδων. Η δεύτερη που είναι η Empirical Mode Decomposition (EMD) [Huang_1998] αφορά την ανάλυση των δεδομένων σε συνιστώσες AM-FM μορφής καθοδηγούμενη από τα δεδομένα, για την ανάδειξη χαρακτηριστικών δεδομένων μη-στάσιμων και μη-γραμμικών διαδικασιών. Ο συνδυασμός των μεθόδων είναι η εύρεση του συχνοτικού περιεχομένου ενός σήματος με την χρήση του τελεστή Teager- Kaiser από τις επιμέρους συνιστώσες που έχουν προκύψει με την μέθοδο (EMD) και ονομάζεται μετασχηματισμός Teager-Huang και αποτελεί μια εναλλακτική δυνατότητα στην εύρεση του φάσματος ενός σήματος. Στα επόμενα κεφάλαια περιγράφουμε τα υπό εξέταση σήματα, τους μηχανισμούς καταγραφής τους, μια ανασκόπηση των βασικών επεξεργασιών που έχουν υποστεί και την ανάλυση στην οποία υποβλήθηκαν στα πλαίσια της συγκεκριμένης εργασίας. Έτσι στο κεφάλαιο 2 παρουσιάζουμε τα υπό ανάλυση σήματα, αναφέροντας τις διαδικασίες με τις οποίες προκύπτουν και τις διατάξεις μέτρησής τους. Στο κεφάλαιο 3 κάνουμε μια ανασκόπηση των τεχνικών επεξεργασίας των σημάτων γεωηλεκτρικού δυναμικού μέχρι σήμερα. Στα κεφάλαια 4, 5 και 6 αναφέρουμε το θεωρητικό υπόβαθρο, την πειραματική διαδικασία επεξεργασίας που ακολουθήθηκε και τα συμπεράσματα με την εφαρμογή του τελεστή Teager, της μεθόδου EMD και του μετασχηματισμού Teager-Huang αντίστοιχα που αποτελούν πρωτότυπη εφαρμογή στον χώρο των γεωφυσικών σημάτων. Στο κεφάλαιο 7 αναφερόμαστε σε επεξεργασία που έχει γίνει υποβοηθητικά ή συμπληρωματικά της επεξεργασίας των προηγούμενων κεφαλαίων. Για τα πειράματα των κεφαλαίων 4-7, αναφέρουμε το όνομα του script αρχείου που τα υλοποιεί εντός παρενθέσεων δίπλα στο όνομα του πειράματος. Ο σχετικός κώδικας μπορεί να βρεθεί στο συνοδευτικό CD της διπλωματικής εργασίας. Στο κεφάλαιο 8 καταλήγουμε με τα κύρια συμπεράσματα και ορισμένες κατευθύνσεις περαιτέρω επεξεργασίας ως επέκταση της τρέχουσας διπλωματικής. / This work concerns the study and implementation of the Teager-Kaiser Operator, the Empirical Mode Decomposition method, and the combination of them known as Teager-Huang transformation.