Dissertations / Theses on the topic 'Surface anomaly'
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1
Le, Jiahui. "Application of Deep-learning Method to Surface Anomaly Detection." Thesis, Linnéuniversitetet, Institutionen för datavetenskap och medieteknik (DM), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-105240.
Abstract:
In traditional industrial manufacturing, due to the limitations of science and technology, manual inspection methods are still used to detect product surface defects. This method is slow and inefficient due to manual limitations and backward technology. The aim of this thesis is to research whether it is possible to automate this using modern computer hardware and image classification of defects using different deep learning methods. The report concludes, based on results from controlled experiments, that it is possible to achieve a dice coefficient of more than 81%.
2
Richmond, N. C., L. L. Hood, and A. B. Binder. "Correlations between magnetic anomalies and surface geology antipodal to lunar impact basins." AMER GEOPHYSICAL UNION, 2005. http://hdl.handle.net/10150/623350.
Abstract:
Previous work has shown that the strongest concentrations of lunar crustal magnetic anomalies are located antipodal to four large, similarly aged impact basins (Orientale, Serenitatis, Imbrium, and Crisium). Here, we report results of a correlation study between magnetic anomaly clusters and geology in areas antipodal to Imbrium, Orientale, and Crisium. Unusual geologic terranes, interpreted to be of seismic or ejecta origin associated with the antipodal basins, have been mapped antipodal to both Orientale and Imbrium. All three antipode regions have many high-albedo swirl markings. Results indicate that both of the unusual antipode terranes and Mare Ingenii (antipodal to Imbrium) show a correlation with high-magnitude crustal magnetic anomalies. A statistical correlation between all geologic units and regions of medium to high magnetization when high-albedo features are present (antipodal to Orientale) may suggest a deep, possibly seismic origin to the anomalies. However, previous studies have provided strong evidence that basin ejecta units are the most likely sources of lunar crustal anomalies, and there is currently insufficient evidence to differentiate between an ejecta or seismic origin for the antipodal anomalies. Results indicate a strong correlation between the high-albedo markings and regions of high magnetization for the Imbrium, Orientale, and Crisium antipodes. Combined with growing evidence for an Imbrian age to the magnetic anomalies, this supports a solar wind deflection origin for the lunar swirls.
3
Wei, Li. "Processing and Interpretation of Three-Component Borehole/Surface Seismic Data over Gabor Gas Storage Field." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1441043179.
4
Harada, Yuki. "Interactions of Earth's Magnetotail Plasma with the Surface, Plasma, and Magnetic Anomalies of the Moon." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188495.
5
Terra, Nova Filipe. "The time-dependence of reversed flux patches in archeomagnetic field models and numerical dynamo simulations : implication for the South Atlantic Anomaly evolution." Thesis, Nantes, 2018. http://www.theses.fr/2018NANT4023/document.
Abstract:
Les modèles de champ archéomagnétique et les simulations numériques de dynamos fournissent des informations importantes sur la géodynamique. J'ai étudié l’existence et la mobilité des patches de flux inverse (PFI) dans les modèles de champ archéomagnétique. J'ai comparé le suivi des PFIs avec les anomalies sismologiques à la base du manteau pour explorer si les PFIs ont des emplacements privilégiés prescrits par l'hétérogénéité latérale à la base du manteau. Les PFI sont ainsi interprétés en termes de dynamique de noyau et d'interactions thermiques noyau-manteau. La corrélation en co-latitude et le décalage en longitude permettent d'inférer l'orientation azimutale du champ toroidal et la présence d'un large upwelling au sommet du noyau. L'Anomalie de l'Atlantique Sud (AAS) est une région de faible intensité géomagnétique à la surface de la Terre, qui est communément attribuée aux PFIs sur la frontière noyau manteau (FNM). Alors que l’AAS est clairement affecté par la région de flux inverse sous l'Atlantique Sud, je montre que la relation entre l’AAS et les PFIs n'est pas simple. L'anomalie est déterminée par l'interaction de plusieurs patches de flux (normal et inverse) à la FNM. Des scenarios simples de variation séculaire (VS) suggèrent que si le déplacement de l’AAS peut être expliqué par l'advection, sa chute d'intensité nécessite la diffusion magnétique. J'ai déterminé si l'hétérogénéité thermique du manteau inférieur pouvait expliquer l'emplacement de l’AAS avec des dynamos numériques dont le flux de chaleur à la FMN est hétérogène. Les histogrammes des coordonnées des minima d'intensité de surface montrent deux pics de position longitudinale préférée dont un est proche de la longitude actuelle de l’AAS. Les ingrédients pour reproduire les coordonnées de l'AAS sont liés à l'asymétrie nord-sud du flux normal et inverseArcheomagnetic field models and numerical dynamo simulations provide important insights to the geodynamo. I investigated the existence and mobility of reversed flux patches (RFPs) in archeomagnetic field models. I compared the tracking of RFPs with seismic anomalies of the lowermost mantle to explore if RFPs have preferred locations prescribed by lower mantle lateral heterogeneity and interpreted in terms of core dynamics and core-mantle thermal interactions. Correlation in co-latitude and a shift in longitude allowed inferring azimuthal orientation of toroidal field below the core-mantle boundary (CMB) and the presence of large fluid upwelling structures at the top of the core. The South Atlantic Anomaly (SAA) is a region of weak geomagnetic field intensity at the Earth's surface, which is commonly attributed to RFPs on the CMB. While the SAA is clearly affected by the reversed flux region below the South Atlantic, I showed that the relation between the SAA and RFPs is not straightforward. The SAA minimum is determined by the interplay among several robust flux patches at the CMB. Simple secular variation (SV) scenarios suggest that while the SAA path can be explained by advection, its intensity decrease requires magnetic diffusion. Investigating whether lower mantle thermal heterogeneity may explain the location of the SAA was tested with run numerical dynamos with heterogeneous CMB heat flux. Histograms of the coordinates of surface intensity minima show two peaks of preferred longitudinal position of weakest surface field intensity, one close to the present SAA minimum longitude. The ingredients to reproduce the SAA coordinates are related to north-south asymmetry of normal and reversed flux
6
Michaud, Réjean. "Sensibilite de previsions meteorologiques a longue echeance aux anomalies de temperature superficielle des oceans." Paris 6, 1987. http://www.theses.fr/1987PA066528.
Abstract:
Nous observons une grande variabilite interannuelle des moyennes mensuelles et saisonnieres de la circulation atmospherique. Cette variabilite ne peut s'expliquer uniquement par les mecanismes internes de l'atmosphere, specialement dans le cas des regions intertropicales, la variabilite interannuelle des conditions a sa frontiere inferieure, en particulier les temperatures superficielles des oceans, en est donc l'origine, comme le demontre l'observation de circulations atmospheriques tres voisines lors du retour des memes temperatures oceaniques exceptionnelles. Ainsi, une certaine predicibilite des moyennes temporelles de la circulation atmospherique peut-elle etre fondee sur la prevision des anomalies de temperature oceanique. Cependant, en raison de l'existence d'un delai dans le developpement de l'impact de ces anomalies sur l'atmosphere, le probleme de la prevision meteorologique a longue echeance nous amene a poser la question suivante: a partir de quelle echeance la prise en compte des anomalies de temperature oceanique (nous supposons celles-ci parfaitement predites) a-t-elle une influence significative sur la prevision. Les previsions numeriques realisees a l'aide du modele de circulation generale de l'atmosphere du lmd montrent que les anomalies de temperature oceanique proche-equatoriales influencent tres rapidement, en quelques jours, la circulation atmospherique predite. De meme, cette influence se poursuit sur periode relativement longue, superieure au mois. Ainsi, ces deux resultats indiquent que la pleine influence des anomalies de temperature oceanique sur la circulation atmospherique simulee par le modele ne peut etre obtenue que par la prise en compte de ces anomalies sur une periode superieure au mois
7
Xie, Yong. "Transmission Properties of Sub-Wavelength Metallic Slits and Their Applications." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/195217.
Abstract:
With the manufacture of nano-scale features in the last ten years, it is possible to do optical experiments on features as small as a tenth/hundredth wavelength. It turns out that the experimental data cannot be explained by classical diffraction theories. Thus, it is necessary to develop new methods or use existing approaches which are effective in other fields, to solve problems in photonics. We use finite difference time domain (FDTD), to study transmission properties of sub-wavelength slits in a metallic film. By doing simulations on periodic and single slits, we confirm that the TE mode has a cutoff while a TM mode always has a propagating mode in the small apertures. Then we find that the transmittance is minimum when the array period is equal to the wavelength of surface plasmon polariton (SPP) at normal incidence. In fact, the SPP-like waves exist in both periodic and isolated slits, and they help the transmittance of small apertures. In order to establish the role of SPP in the transmission mechanism, it is necessary to single out each mode from the total fields. We developed Bloch mode method (BMM) to calculate the amplitudes of the lowest N orders, and the amplitudes tell us which one is dominant (not including the guided mode) at high and low transmission. BMM converges very fast and it is more accurate than FDTD since it does not suffer from numerical dispersion. Both methods can resolve the Wood anomaly and SPP anomaly; however, FDTD converges very slowly at the SPP resonance and oscillates around the value obtained through BMM at the Wood anomaly. BMM is not sensitive to material types, incident angles, and anomalies; it will be a useful tool to investigate similar problems.
8
Tufekci, Sinan. "Combined Surface-Wave and Resistivity Imaging for Shallow Subsurface Characterization." Ohio University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1250891786.
9
Saballos, Jose Armando. "Short and Long Term Volcano Instability Studies at Concepción Volcano, Nicaragua." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4757.
Abstract:
Concepción is the most active composite volcano in Nicaragua, and is located on Ometepe Island, within Lake Nicaragua. Moderate to small volcanic explosions with a volcanic explosivity index (VEI) of 1-2 have been characteristic of this volcano during the last four decades. Although its current activity is not violent, its volcanic deposits reveal stages of violent activity involving Plinian and sub-Plinian eruptions that deposited vast amounts of volcanic tephra in the Atlantic Ocean. These observations, together with the 31,000 people living on the island, make Concepción volcano an important target for volcanological research.
My research focuses on the investigation of the stability of the volcano edifice of Concepción, using geophysical data such as gravity, geodetic global positioning system (GPS), sulphur dioxide (SO2) flux, real-time seismic amplitude (RSAM), and satellite remotely-sensed data. The integration of these data sets provides information about the short-term behavior of Concepción, and some insights into the volcano's long-term behavior.
This study has provided, for the first time, information about the shallow dynamics of Concepción on time scales of days to weeks. I furnish evidence that this volcano is not gravitationally spreading in a continuous fashion as previously thought, that its bulk average density is comparable to that of a pile of gravel, that the volcano edifice is composed of two major distinctive lithologies, that the deformation field around the volcano is recoverable in a matter of days, and that the deformation source is located in the shallow crust. This source is also degassing through the relatively open magmatic conduit. There are, however, several remaining questions. Although the volcano is not spreading continuously there is the possibility that gravitational spreading may be taking place in a stick-slip fashion. This has important implications for slope stability of the volcano, and the
associated hazards. The factors influencing the long term slope stability of the volcano are still not fully resolved, but internal volcanic processes and anthropogenic disturbances appear to be the major factors.
10
Berthiere, Clément. "Entanglement, boundaries and holography." Thesis, Tours, 2017. http://www.theses.fr/2017TOUR4017.
Abstract:
La notion d’entropie d’intrication a eu un profond impact sur la physique théorique, particulièrement depuis ces dix dernières années. D’abord introduite afin expliquer l’entropie des trous noirs, son champ d’application s’est par la suite ouvert à une grande variété de domaines de recherche, de la matière condensée à la gravitation quantique, de l’information quantique à la théorie quantique des champs. Dans ce contexte scientifique effervescent, l’entropie d’intrication apparait comme un outil central et doit donc intensivement être étudiée. A l’origine de cette thèse se trouve le désir de mieux comprendre cette entropie. D’intéressants développements concernant les effets de bord sur l’entropie d’intrication ont vu le jour récemment. Nous proposons donc d’explorer comment le bord d’un espace affecte l’entropie, en particulier dans la situation où la surface d’intrication intersecte ce bord. Nous présentons des calculs explicites de l’entropie d’intrication en espace plat avec bords. Nous montrons que des termes induits par ces bords apparaissent dans l’entropie et nous soulignons le rôle prépondérant que jouent les conditions aux bords. Nous étudions ensuite la contribution de bord dans le terme logarithmique de l’entropie d’intrication en dimensions trois et quatre. Nous calculons en premier lieu ce terme en théorie des champs pour la théorie N = 4 de Yang-Mills, puis nous répétons ce calcul de manière holographique. Nous montrons que ces deux méthodes de calcul donnent le même résultat, si du côté théorie des champs les conditions aux bords préservent la moitié de la supersymétrie et que du côté gravité l’extension du bord dans le bulk est une surface minimaleThe entanglement entropy has had a tremendous and profound impact on theoretical physics, particularly since the last decade. First introduced in an attempt to explain black holes entropy, it has then found applications in a wide range of research areas, from condensed matter physics to quantum gravity, from quantum information to quantum field theory. In this exciting scientific context, the entanglement entropy has thus emerged as a useful and pivotal tool, and as such justifies the need to be intensively studied. At the heart of this thesis therefore lies the desire to better understand the entanglement entropy. Interesting developments during the recent years concern the boundary effects on the entanglement entropy. This dissertation proposes to explore the question of how the presence of spacetime boundaries affects the entropy, specifically in situations where the entangling surface intersects these boundaries. We present explicit calculations of entanglement entropy in flat spacetime with plane boundaries. We show that boundary induced terms appear in the entropy and we emphasize the prominent role of the boundary conditions. We then study the boundary contribution to the logarithmic term in the entanglement entropy in three and four dimensions. We perform the field theoretic computation of this boundary term for the free N = 4 super-gauge multiplet and then repeat the same calculation holographically. We show that these two calculations are in agreement provided that on the field theory side one chooses the boundary conditions which preserve half of the full supersymmetry and that on the gravity side the extension of the boundary in the bulk is minimal
11
Yang, Can. "Time-lapse Analysis of Borehole and Surface Seismic Data, and Reservoir Characterization of the Ketzin CO2 Storage Site, Germany." Doctoral thesis, Uppsala universitet, Geofysik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-163013.
Abstract:
The CO2SINK (and CO2MAN) project is the first onshore CO2 storage project in Europe. The research site is located near the town of Ketzin, close to Potsdam in Germany. Injection started in June 2008, with a planned injection target of 100,000 tonnes of CO2. In February 2011, around 45, 000 tons of CO2 had been injected into the saline aquifer at an approximate depth of 630 m. This thesis focuses on time-lapse analysis of borehole seismic data, surface seismic data and reservoir characterization at the Ketzin site. Baseline Moving Source Profiling (MSP) data were acquired in the borehole Ketzin 202/2007 (OW2), along seven lines in 2007. The zero-offset Vertical Seismic Profile (VSP) data were acquired in the same borehole. The main objective of the VSP and MSP survey was to generate high-resolution seismic images around the borehole. After modeling and data processing, the sandy layers within the Stuttgart Formation can potentially be imaged in the VSP and MSP data whereas reflections from these layers are not as clearly observed in the 3D surface seismic data. 2D and pseudo-3D time-lapse seismic surveys were conducted at the Ketzin site. Interpretation of 2D baseline and repeat stacks shows that no CO2 leakage related time lapse signature is observable where the 2D lines allow monitoring of the reservoir. This is consistent with the time-lapse results of the 3D surveys showing an increase in reflection amplitude just centered around the injection well. The results from the pseudo-3D surveys are also consistent with the 3D seismic time-lapse studies and show that the sparse pseudo-3D geometry can be used to qualitatively map the CO2 in the reservoir with significantly less effect than the full 3D surveying. The 2nd pseudo-3D repeat survey indicates preferential migration of the CO2 to the west. There are no indications of migration into the caprock on either of the repeat surveys. Amplitude Versus Offset (AVO) analysis was performed on both 2D and 3D repeat surveys. A Class 3 AVO anomaly is clearly observed on the 3D repeat data and matches the synthetic modeling well. No AVO anomaly was observed on the 2D repeat data, which was anticipated, but the result shows signs of a pressure response at the reservoir level in the data. Reflection coefficients were calculated using surface seismic data (3D and pseudo-3D) at the site. Pre-injection calculations agree well with calculations from logging data. Post-injection calculations are in general agreement with the seismic modeling, but generally show higher amplitudes than those expected. The full 3D data show a better image of the reflection coefficients before and after injection than the pseudo-3D data and can potentially be used to make quantitative calculations of CO2 volumes. The pseudo-3D data only provide qualitative information.
12
Sadriji, Besnik. "Analysis and characterization of the damage phenomena occurring from handling and service surface anomalies." Thesis, université Paris-Saclay, 2022. http://www.theses.fr/2022UPAST082.
Abstract:
Ces travaux de thèse ont porté sur l'étude des phénomènes d'endommagement induits par l'introduction d'anomalies de surface de type choc ou rayure, lors d'opérations de maintenance des disques de turbine haute pression. D'une part, ces dernières créent une concentration de contraintes en fond d'anomalie liée au défaut géométrique, qui, couplée à la sévérité des chargements thermomécaniques subits par les disques, amène à l'amorçage et la propagation d'une fissure courte. D'autre part, ces anomalies s'accompagnent de déformations dans la matière qui induisent de l'écrouissage et des contraintes résiduelles. Ces dernières ont un effet du premier ordre sur la propagation de la fissure qu'il est nécessaire de prendre en compte. Ainsi l'objectif est de caractériser ces phénomènes induits par l'introduction des anomalies de surface, à savoir le comportement d'une fissure courte dans un champ de contraintes résiduelles.Concernant la caractérisation du comportement d'une fissure courte, une campagne expérimentale novatrice a été mise en place. Lors de cette dernière, des essais de fatigue uniaxiaux et biaxiaux ont été réalisés ainsi que des simulations numériques de propagation de fissure. D'une part, cette campagne expérimentale permet de mettre en exergue l'effet de la contrainte T sur la propagation de fissure. D'autre part, elle fournit un protocole expérimental permettant d'obtenir des fissures courtes et de caractériser leur comportement. Enfin, elle donne des pistes vers la prise en compte de l'effet de fissure courte via la contrainte T.Dans le but de caractériser les contraintes résiduelles, une campagne de caractérisation par diffraction des rayons X à l'European Synchrotron Radiation Facility (ESRF) de Grenoble a été menée. La mesure des distances interatomiques permet de déterminer les déformations puis les contraintes résiduelles induites par l'anomalie. Les résultats obtenus sont cohérents avec ce qui était attendu : de forts niveaux de contraintes multiaxiales, de forts gradients et une portée sous la surface conséquente. Le modèle d'introduction de choc a été amélioré afin de pouvoir le comparer avec les résultats expérimentaux.Une stratégie d'intégration de ces différents phénomènes dans un modèle incrémental est proposé dans les perspectives afin de tenir compte de la fissuration causée par des anomalies de surfaceThis research work concerns the study of the induced physical phenomena by the introduction of handling surface anomalies such as dents or scratches, on high pressure turbine disks. On one hand, they create a geometrical stress concentration at the anomaly root and combined with the severe thermomechanical loadings undergone by the disks, leads to a short crack initiation and propagation. On the other hand, these anomalies induce deformations which lead to hardening and residual stresses in the material. The latter have an important influence on the crack propagation and is necessary to take into account. Thus, the aim is to characterize these phenomena induced by the introduction of surface anomalies, namely the short crack effect and the residual stress field.For the short crack effect characterization, a pioneering experimental campaign has been set up implying uniaxial and multiaxial fatigue tests as well as numerical simulations in crack propagation. This experimental campaign highlights the T-stress effect on the crack propagation first. Then, it gives an experimental protocol to obtain short cracks and characterize their behavior. Finally, it gives a lead to take into account the short crack effect via the T-stress.With the aim of characterizing the residual stress field, Synchrotron X-ray diffraction measurements have been performed at the European Synchrotron Radiation Facility (ESRF) at Grenoble. The determination of the interatomic distances allows to determine the strains and the induced residual stresses by the anomaly. The results show important 3D stress levels, gradients and a substantial in-depths extent, as expected. The numerical model of a dent introduction has been improved to compare the experimental results with.A strategy to take into account these phenomena in the Incremental model is given in the perspectives in order to consider crack propagation from surface anomalies
13
Benmoussat, Mohammed Seghir. "Hyperspectral imagery algorithms for the processing of multimodal data : application for metal surface inspection in an industrial context by means of multispectral imagery, infrared thermography and stripe projection techniques." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4347/document.
Abstract:
Le travail présenté dans cette thèse porte sur l'inspection de surfaces métalliques industrielles. Nous proposons de généraliser des méthodes de l'imagerie hyperspectrale à des données multimodales comme des images optiques multi-canales, et des images thermographiques multi-temporelles. Dans la première application, les cubes de données sont construits à partir d'images multi-composantes pour détecter des défauts de surface. Les meilleures performances sont obtenues avec les éclairages multi-longueurs d'ondes dans le visible et le proche IR, et la détection du défaut en utilisant l'angle spectral, avec le spectre moyen comme référence. La deuxième application concerne l'utilisation de l'imagerie thermique pour l'inspection de pièces métalliques nucléaires afin de détecter des défauts de surface et sub-surface. Une approche 1D est proposée, basée sur l'utilisation du kurtosis pour sélectionner la composante principale parmi les premières obtenues après réduction des données avec l’ACP. La méthode proposée donne de bonnes performances avec des données non-bruitées et homogènes, cependant la SVD avec les algorithmes de détection d'anomalies est très robuste aux perturbations. Finalement, une approche, basée sur les techniques d'analyse de franges et la lumière structurée est présentée, dans le but d'inspecter des surfaces métalliques à forme libre. Après avoir déterminé les paramètres décrivant les modèles de franges sinusoïdaux, l'approche proposée consiste à projeter une liste de motifs déphasés et à calculer l'image de phase des motifs enregistrés. La localisation des défauts est basée sur la détection et l'analyse des franges dans les images de phaseThe work presented in this thesis deals with the quality control and inspection of industrial metallic surfaces. The purpose is the generalization and application of hyperspectral imagery methods for multimodal data such as multi-channel optical images and multi-temporal thermographic images. In the first application, data cubes are built from multi-component images to detect surface defects within flat metallic parts. The best performances are obtained with multi-wavelength illuminations in the visible and near infrared ranges, and detection using spectral angle mapper with mean spectrum as a reference. The second application turns on the use of thermography imaging for the inspection of nuclear metal components to detect surface and subsurface defects. A 1D approach is proposed based on using the kurtosis to select 1 principal component (PC) from the first PCs obtained after reducing the original data cube with the principal component analysis (PCA) algorithm. The proposed PCA-1PC method gives good performances with non-noisy and homogeneous data, and SVD with anomaly detection algorithms gives the most consistent results and is quite robust to perturbations such as inhomogeneous background. Finally, an approach based on fringe analysis and structured light techniques in case of deflectometric recordings is presented for the inspection of free-form metal surfaces. After determining the parameters describing the sinusoidal stripe patterns, the proposed approach consists in projecting a list of phase-shifted patterns and calculating the corresponding phase-images. Defect location is based on detecting and analyzing the stripes within the phase-images
14
Lguensat, Redouane. "Learning from ocean remote sensing data." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2017. http://www.theses.fr/2017IMTA0050/document.
Abstract:
Reconstruire des champs géophysiques à partir d'observations bruitées et partielles est un problème classique bien étudié dans la littérature. L'assimilation de données est une méthode populaire pour aborder ce problème, et se fait par l'utilisation de techniques classiques, comme le filtrage de Kalman d’ensemble ou des filtres particulaires qui procèdent à une évaluation online du modèle physique afin de fournir une prévision de l'état. La performance de l'assimilation de données dépend alors fortement de du modèle physique. En revanche, la quantité de données d'observation et de simulation a augmenté rapidement au cours des dernières années. Cette thèse traite l'assimilation de données d'une manière data-driven et ce, sans avoir accès aux équations explicites du modèle. Nous avons développé et évalué l'assimilation des données par analogues (AnDA), qui combine la méthode des analogues et des méthodes de filtrage stochastiques (filtres Kalman, filtres à particules, chaînes de Markov cachées). Des applications aux modèles chaotiques simplifiés et à des études de cas de télédétection réelle (température de surface de lamer, anomalies du niveau de la mer), nous démontrons la pertinence d'AnDA pour l'interpolation de données manquantes des systèmes dynamiques non linéaires et à haute dimension à partir d'observations irrégulières et bruyantes.Motivé par l'essor du machine learning récemment, la dernière partie de cette thèse est consacrée à l'élaboration de modèles deep learning pour la détection et de tourbillons océaniques à partir de données de sources multiples et/ou multi temporelles (ex: SST-SSH), l'objectif général étant de surpasser les approches dites expertesReconstructing geophysical fields from noisy and partial remote sensing observations is a classical problem well studied in the literature. Data assimilation is one class of popular methods to address this issue, and is done through the use of classical stochastic filtering techniques, such as ensemble Kalman or particle filters and smoothers. They proceed by an online evaluation of the physical modelin order to provide a forecast for the state. Therefore, the performanceof data assimilation heavily relies on the definition of the physical model. In contrast, the amount of observation and simulation data has grown very quickly in the last decades. This thesis focuses on performing data assimilation in a data-driven way and this without having access to explicit model equations. The main contribution of this thesis lies in developing and evaluating the Analog Data Assimilation(AnDA), which combines analog methods (nearest neighbors search) and stochastic filtering methods (Kalman filters, particle filters, Hidden Markov Models). Through applications to both simplified chaotic models and real ocean remote sensing case-studies (sea surface temperature, along-track sea level anomalies), we demonstrate the relevance of AnDA for missing data interpolation of nonlinear and high dimensional dynamical systems from irregularly-sampled and noisy observations. Driven by the rise of machine learning in the recent years, the last part of this thesis is dedicated to the development of deep learning models for the detection and tracking of ocean eddies from multi-source and/or multi-temporal data (e.g., SST-SSH), the general objective being to outperform expert-based approaches
15
Fachin, Sergio Junior da Silva. "O sinal de potencial espontâneo em investigações ambientais: fatores que condicionam a amplitude de uma anomalia." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/14/14132/tde-12062018-165148/.
Abstract:
Anomalias de potencial espontâneo com amplitudes de dezenas a centenas de milivolts são observadas em plumas de contaminação apesar de não serem explicadas por modelos de geobateria normalmente utilizados na geofísica de exploração. Modelos recentemente propostos, denominados de biogeobateria, assumem que estruturas orgânicas produzidas por micro- organismos assumem a função de condução eletrônica que os minerais condutivos exercem no modelo clássico de geobateria. O modelo de biogeobateria, por outro lado, se assemelha com o que se denomina sistemas bioeletroquímicos ou células de combustível microbianas em áreas da biotecnologia (bioenergia). O presente trabalho explora esta semelhança para desenvolver um experimento de laboratório que utiliza um sistema bioeletroquímico como modelo análogo de biogeobateria para mostrar que este modelo é capaz de explicar o sinal de potencial espontâneo observado em campo. Os resultados experimentais e de modelagem numérica mostram que a amplitude do potencial elétrico depende: da área do catodo, da resistência interna da biogeobateria, da existência de um fluxo adicional de cátions do anodo para o catodo, da resistividade elétrica do meio e da separação do anodo com o catodo. Os resultados experimentais mostraram-se compatíveis com observações de campo obtidas na caracterização hidrogeofísica de uma pluma de contaminação, proveniente de um aterro de resíduos (lixão). A pluma de contaminação se estende por dois níveis em profundidade, comprometendo a qualidade do aquífero livre e certamente do aquífero confinado. A ano- malia de potencial espontâneo alcança amplitude de 70mV sobre o aquífero livre, sendo praticamente desprezível sobre o aquífero confinado, tal como se observa em laboratório em modelos correspondentes. O experimento com biogeobateria mostra também que as reações químicas desencadeadas no anodo oxidam o substrato orgânico, reduzindo a demanda química de oxigênio em 10 % no experimento considerado. Este resultado mostra que sinais de potencial espontâneo em áreas contaminadas podem ser considerados como indicativos de processos oxidativos ocorrendo em um substrato orgânico sendo, pois, de relevância para o reconhecimento de processos de atenuação natural em terrenos com contaminantes orgânicos.Self-potential anomalies with amplitudes of tens to hundreds of millivolts are observed in contaminated plumes despite not fully explained by geobattery models commonly used in geophysical exploration. Recently proposed models, termed as biogeobattery, assume that organic structures produced by microorganisms act as electronic conductors, as it is done by conductive minerals in standard geobattery models. The biogeobattery model in addition resembles what is termed as bioelectrochemical system or microbial fuel cell in fields of the research in biotechnology (bioenergy). This study explores this similarity to develop a laboratory experiment using a bioelectrochemical system as an analog model for a biogeobattery, to show that this model is able to explain the spontaneous potential signals observed in many geophysical surveys over contaminated sites. Experimental and modeling results show that the amplitude of the electric potential from a biogeobattery depends on: the area of ? the cathode, its internal resistance, the existence of an additional flow of cations (from the anode to the cathode), the electrical resistivity of the medium and the separation of anode to the cathode. In general, the experimental results were compatible with field observations at a contamination plume produced by a landfill. The contamination plume extends over two levels deep, degrading the quality of the unconfined and confined aquifers. The amplitude of the self-potential anomaly reaches 70mV over the unconfined aquifer and is negligible over the confined aquifer, as observed in the corresponding models of the laboratory experiment. The biogeobattery experiment also shows that chemical reactions at the system anode were able do oxidize the organic substrate, reducing in 10% its chemical oxygen demand. This result shows that self-potential signals in contaminated areas can be regarded as indicative of oxidative processes taking of buried organic matter and, as such, a proxy of biodegradation processes leading to natural attenuation of organic ontaminants.
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Cotte, Nathalie. "Détermination des variations latérales de la lithosphère par l'analyse des ondes de surface enregistrées par des réseaux régionaux." Phd thesis, Grenoble 1, 2000. http://tel.archives-ouvertes.fr/tel-00703264.
Abstract:
Les ondes de surface de période 10-100 secondes sont sensibles à la rigidité de la lithosphère échantillonnée. Dans ce travail de thèse, nous nous sommes intéressés à l'étude des variations latérales de la lithosphère par l'analyse des ondes de surface. La longueur d'onde des variations latérales étudiées est de l'ordre de grandeur décakilométrique. Les méthodes habituellement utilisées avec des stations sismologiques espacées de plusieurs centaines de kilomètres ne sont donc plus satisfaisantes. C'est pourquoi nous avons développé des analyses dites de réseaux denses ou régionaux. Ainsi nous pouvons déterminer les variations latérales de la structure lithosphérique et étudier la propagation des ondes de surface à l'échelle régionale. Nous avons appliqué ces analyses de réseau pour trois études régionales différentes. Tout d'abord nous avons montré les variations brutales de la structure crustale de part et d'autre de la suture du Tsangpo au sud du plateau tibétain. Pour cela, nous avons analysé la vitesse de phase locale ainsi que les variations d'amplitude au travers de la suture. Au nord de la suture du Tsangpo nous avons déterminé une zone à moindre vitesse dans la croûte inférieure alors que nous ne l'observons pas au sud de la suture. Nous avons aussi étudié la lithosphère dans les Alpes françaises et nous avons montré qu'elle s'épaississait d'ouest en est, de 85 à plus de 200 km d'épaisseur sous l'axe de la chaîne alpine. Par ailleurs, nous nous sommes intéressés aux anomalies de la propagation des ondes de surface dans cette région en dissociant les effets dus aux échelles globale et locale. Finalement, nous avons aussi travaillé sur la zone de Sorgenfrei-Tornquist qui sépare l'Europe phanérozoïque à l'ouest de l'Europe paléozoïque à l'est. Nous montrons qu'au sud-ouest de cette zone la lithosphère est peu épaisse, autour de 50-100 km, et qu'au nord-est elle atteint une épaisseur supérieure à 200 km sous le bouclier baltique. Au niveau de la transition, la lithosphère est épaisse de 120 km .
17
Tran, Ngoc Minh. "Applications of nonlinear magneto-photonics at the nanoscale." Thesis, Le Mans, 2018. http://www.theses.fr/2018LEMA1029/document.
Abstract:
La génération de seconde harmonique magnétique (mSHG pour magnetic Second Harmonic Generation) est un phénomène physique très sensible apparaissant grâce aux brisures de symétrie aux niveaux des surfaces et interfaces des structures métalliques magnétiques. Elle constitue donc un outil puissant pour explorer ce type d'interfaces et des nanostructures. Dans ce travail, nous nous intéressons aux couplages et interactions entre la mSHG et les ondes électromagnétiques pouvant se propager en surface des matériaux. Un intérêt spécifique est porté sur l’ excitation de (i) plasmon polaritons de surfaces (SPP) dans des films métalliques en structures multicouches, (ii) d'anomalies de diffraction (dîtes de Wood) dans des nanostructures métalliques périodiques. Pour étudier l'influence de l'excitation linéaire et non-linéaire des SPP sur la mSHG, l'intensité du signal réfléchi par génération de seconde harmonique (SH) et le contraste magnétique lié à ce signal ont été mesurés par la technique de l'effet Kerr magnéto-optique transverse (MOKE) en fonction de l'angle d'incidence. Via l'utilisation de sources lasers femtosecondes émettant dans le proche infrarouge, domaine spectral où les variations de la dispersion des SPP et du coefficient d'amortissement sont significatives, nous avons pu distinguer les différentes contributions linéaires et non-linéaires aux processus d'excitation. Ce travail de thèse a ainsi permis de montrer que l’accord de phase entre la mSHG et les ondes électromagnétiques de surface peuvent contribuer très efficacement à l'augmentation des signaux SH et de contraste magnétique associéOwing to surface and interface sensitivity, the magnetic Second Harmonic Generation (mSHG) represents a useful tool to probe magnetic interfaces and nanostructures. This work investigates the coupling and interaction of the mSHG with electromagnetic waves propagating along the surface. Two types of surface waves have been studied: (i) surface plasmon polaritons (SPP) at surfaces of metallic thin films and multilayers, and (ii) the diffraction anomaly at the surface of periodically arranged metallic nanostructures. To study influence of linear and nonlinear excitation of surface waves on the mSHG, the reflected second harmonic (SH) intensity and the magnetic SH contrast in the transverse magneto-optical geometry were measured as a function of the angle of incidence. The use of different femtosecond light sources in the near-infrared optical range, where the SPP dispersion and damping exhibit significant variations, made it possible to disentangle linear and nonlinear contributions to the excitation of surface waves. In this thesis, it is proven that phase-matching of the mSHG and surface electromagnetic waves can lead to the enhancement of both the SH yield and the nonlinear magneto-optical signal. These results are important for controlling of the nonlinear magneto-optical response and could impact the development of magnetic storage devices, label-free biosensors and nonlinear magneto-optical switches
18
Wolf, Gunter. "Diffusionsuntersuchungen an (polymer-modifizierten) Mikroemulsionen mittels Feldgradientenimpuls-NMR-Spektroskopie." Phd thesis, [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=978435966.
19
Täuber, Daniela. "Characterization of heterogeneous diffusion in confined soft matter." Doctoral thesis, Universitätsbibliothek Chemnitz, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-77658.
Abstract:
A new method, probability distribution of diffusivities (time scaled square displacements between succeeding video frames), was developed to analyze single molecule tracking (SMT) experiments. This method was then applied to SMT experiments on ultrathin liquid tetrakis(2-ethylhexoxy)silane (TEHOS) films on Si wafer with 100 nm thermally grown oxide, and on thin semectic liquid crystal films. Spatial maps of diffusivities from SMT experiments on 220 nm thick semectic liquid crystal films reveal structure related dynamics. The SMT experiments on ultrathin TEHOS films were complemented by fluorescence correlation spectroscopy (FCS). The observed strongly heterogeneous single molecule dynamics within those films can be explained by a three-layer model consisting of (i) dye molecules adsorbed to the substrate, (ii) slowly diffusing molecules in the laterally heterogeneous near-surface region of 1 - 2 molecular diameters, and (iii) freely diffusing dye molecules in the upper region of the film. FCS and SMT experiments reveal a strong influence of substrate heterogeneity on SM dynamics. Thereby chemisorption to substrate surface silanols plays an important role. Vertical mean first passage times (mfpt) in those films are below 1 µs. This appears as fast component in FCS autocorrelation curves, which further contain a contribution from lateral diffusion and from adsorption events. Therefore, the FCS curves are approximated by a tri-component function, which contains an exponential term related to the mfpt, the correlation function for translational diffusion and a stretched exponential term for the broad distribution of adsorption events. Lateral diffusion coefficients obtained by FCS on 10 nm thick TEHOS films, thereby, are effective diffusion coefficients from dye transients in the focal area. They strongly depend on the substrate heterogeneity. Variation of the frame times for the acquisition of SMT experiments in steps of 20 ms from 20 ms to 200 ms revealed a strong dependence of the corresponding probability distributions of diffusivities on time, in particular in the range between 20 ms and 100 ms. This points to average dwell times of the dye molecules in at least one type of the heterogeneous regions (e.g. on and above silanol clusters) in the range of few tens of milliseconds.
Furthermore, time series of SM spectra from Nile Red in 25 nm thick poly-n-alkyl-methacrylate (PnAMA) films were studied. In analogy to translational diffusion, spectral diffusion (shifts in energetic positions of SM spectra) can be studied by probability distributions of spectral diffusivities, i.e. time scaled square energetic displacements. Simulations were run and analyzed to study contributions from noise and fitting uncertainty to spectral diffusion. Furthermore the effect of spectral jumps during acquisition of a SM spectrum was investigated. Probability distributions of spectral diffusivites of Nile Red probing vitreous PnAMA films reveal a two-level system. In contrast, such probability distributions obtained from Nile Red within a 25 nm thick poly-n-butylmethacrylate film around glass transition and in the melt state, display larger spectral jumps. Moreover, for longer alkyl side chains a solvent shift to higher energies is observed, which supports the idea of nanophase separation within those polymers.
20
Huang, Zhijie. "The coupled Ricci flow and the anomaly flow over Riemann surface." Thesis, 2018. https://doi.org/10.7916/D8WH4642.
Abstract:
In the first part of this thesis, we proved a pseudo-locality theorem for a coupled Ricci flow, extending Perelman’s work on Ricci flow to the Ricci flow coupled with heat equation. By use of the reduced distance and the pseudo-locality theorem, we showed that the parabolic rescaling of a Type I coupled Ricci flow with respect to a Type I singular point converges to a non-trivial Ricci soliton. In the second part of the thesis, we prove the existence of infinitely many solutions to the Hull- Strominger system on generalized Calabi-Gray manifolds, more specifically compact non-K \"ahler Calabi-Yau 3-folds with infinitely many distinct topological types and sets of Hodge numbers. We also studied the behavior of the anomaly flow on the generalized Calabi-Gray manifolds, and reduced it to a scalar flow on a Riemann surface. We obtained the long-time existence and convergence after rescaling in the case when the curvature of initial metric is small.
21
Hsieh, Chao-Liang, and 謝兆糧. "An anomaly detection system for roadway surface monitoring based on IoT and machine learning technologies." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/9nj8re.
Abstract:
碩士國立臺灣大學
生物產業機電工程學研究所
106
Roads connecting buildings, villages and even cities play a very important role in our life. The values derived from them are considerable, and they are undoubtedly one of the most important infrastructures in society. In Taiwan, the total length of the roads is 43,365 kilometers. The overall road network links Taiwan''s economy, trade, people, and transportation, reducing the spatial scale of Taiwan as a whole, and shortening the travel time to and from all places. If the road quality is not good, there are many potholes or roads that are sloping down the road on one road. This can cause problems such as uncomfortable rides, driving and passenger safety concerns, vehicle suspension system wear, and traffic accidents. Therefore, road quality and maintenance repairs are extremely important. At present, the maintenance of roads in Taiwan is mainly based on inspections of construction vehicles, returns from the public, and regular repairs. It takes a lot of manpower and time to find the correct road sections that need maintenance. In order to maintain road quality and improve the efficiency of government repairs, an anomaly detection system for roadway surface monitoring based on IoT and machine learning technologies is proposed in this study. The front-end sensing node of this system is equipped with a vibration sensor, a GPS module, and a 4G transmission module. When the vibration amplitude exceeds the set threshold, continuous measurement is performed for a period of time to record the vibration waveform, latitude and longitude, and vehicle speed at the time through 4G transmission module, back to the back-end database. In addition, the back-end computing system analyzes the waveforms of various road surface types (such as regular roads, potholes, manholes, and depressions) and uses machine learning methods to identify road surface types. And these classification results can be displayed on Google Map, and then provide reference for the public and government agencies. Government agencies can choose to repair road sections according to the severity of the road. As a result, the manpower and time costs which are required to examine the surface conditions of the roads can be greatly reduced, and the efficiency of road repairs can be improved.
22
Getahun, Yitea Seneshaw. "Spatial-temporal analyses of climate elements, vegetation characteristics and sea surface temperature anomaly. A Case study in Gojam, Ethiopia." Master's thesis, 2012. http://hdl.handle.net/10362/8320.
Abstract:
Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.Agriculture is the backbone of Gojjam economy as it depends on seasonal characteristics of rainfall. This study analyses the components of regional climate variability, especially La Niña or El Niño Southern Oscillation (ENSO) events and their impact on rainfall variability and the growing season normalized difference vegetation index. The temporal and spatial distribution of temperature, precipitation and vegetation cover have been investigated statistically in two agricultural productive seasons for a period of 9 years (2000–2008), using data from 11 meteorological station and MODIS satellite data in Gojam, Ethiopia. The normalized difference vegetation index (NDVI) is widely accepted as a good indicator for providing vegetation properties and associated changes for large scale geographic regions. Investigations indicate that climate variability is persistent particularly in the small rainy season Belg and continues to affect vegetation condition and thus Belg crop production. Statistical correlation analyses shows strong positive correlation between NDVI and rainfall in most years, and negative relationship between temperature and NDVI in both seasons. Although El Niño and La Niña events vary in magnitude in time, ENSO analyses shows that two strong La Niña years and one strong El Niño years. ENSO analyses result shows that its impact to the region rainfall variability is mostly noticeable but it is inconsistent and difficult to predict all the time. The NDVI anomaly patterns approximately agree with the main documented precipitation and temperature anomaly patterns associated with ENSO, but also show additional patterns not related to ENSO. The spatial and temporal analyses of climate elements and NDVI values for the growing season shows that NDVI and rainfall are very unstable and variable during the 9 years period. ENSO /El Niño and La Niña events analyses shows an increase of vegetation coverage during El Niño episodes contrasting to La Niña episodes. Moreover, El Niño years are good for Belg crop production.
23
Yao, Yi-Ting, and 姚奕廷. "An Anomalous Acoustic Reflection on Hydrophilic Surface under Hexane Confinement by Femtosecond Acoustics: The Study of Acoustic Anomaly at Femtosecond Scale." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/um245x.
Abstract:
碩士國立臺灣大學
光電工程學研究所
106
Many unresolved mysterious phenomena happened at solid/liquid interfaces, for example, the famous Kapitza anomaly illustrates the abnormal thermal transportation across this interface. The energy transmitted from solid to liquid is always higher in the experiment than theoretical prediction. Here the femtosecond acoustics can be of great help in studying this anomaly since the femtosecond acoustic pulses possess sub-THz bandwidth, which is analogous to the dominant acoustic phonons around 1-10K in the Kaptiza problem. In this thesis, we experimentally model the solid/liquid system as GaN/n-Hexane, since GaN is a well-studied acoustic material and n-hexane (C6H14) has an extremely low polarity to minimize the probable interfacial layering effect, which is usually found in the interfacial region of a solid/water system. By in situ monitoring the acoustic echo from the interface of GaN/Air and GaN/Hexane, we are able to study the influence on the echo that originates from the existence of the liquid. In a general condition, the transient reflection of an acoustic pulse from low-loss high- (solid) to lossy low- (liquid) impedance interface has: I. A negative reflection coefficient with an absolute value less than one. II. The peak of the reflected pulse no earlier than the case of solid/air. However, the acoustic reflection from the studied interface in our experiments show an anomalous behavior: The echo came back earlier after applying hexane onto the GaN surface. Nevertheless, the analysis from XPS shows the extra oxygen existence other than the native oxide layer (Ga2O3), which can be clearly observed in the TEM image. The SIMS analysis reveals the excess hydrogen distribution only at the sample surface. These clues drive us to consider that there were some water molecules adsorbs on the hydrophilic GaN surface. Furthermore, the surface-adsorbed water was found to possess an ice-like structure on various hydrophilic surfaces in the literature. Therefore, we then try to investigate the advanced echo by calculating the acoustic reflection based on the simulation structures of GaN / Ga2O3 / Water / Air and GaN / Ga2O3 / Water / n-Hexane. In order to search for the viscosity and elasticity of the water layers, we adopt the Monte Carlo method to help us find the simulation traces with least error compared to the experiment traces. As a result, the advanced echo can be indeed introduced by appropriate combinations of viscoelasticity in the interfacial water layer either next to the air or hexane. Finally, our result indicates that the adsorbed water layer possesses a relaxation dynamics property between ice and elastic-solid in the air, and it becomes more elastic-solid-like under hexane confinement. This finding successfully explains the acoustic anomaly and provides the new insight into the surface-adsorbed water. In fact, this is the first measurement of adsorbed water layer for its mechanical properties in a noninvasive way under ambient condition. Furthermore, we prove the capability of a femtosecond acoustic pulse to probe nanometer-scale structures. In the end, many other possibilities are also discussed as a reason to explain the acoustic reflection anomaly, while they are all found to be unlikely to resolve this issue.
24
Guerreiro, Joana Ferreira. "Assessment of NDVI, land surface temperature and precipitation anomalies for drought monitoring in Bayankhongor province, Mongolia." Master's thesis, 2015. http://hdl.handle.net/10362/17456.
Abstract:
During the last decade Mongolia’s region was characterized by a rapid increase of both severity and frequency of drought events, leading to pasture reduction. Drought monitoring and assessment plays an important role in the region’s early warning systems as a way to mitigate the negative impacts in social, economic and environmental sectors. Nowadays it is possible to access information related to the hydrologic cycle through remote sensing, which provides a continuous monitoring of variables over very large areas where the weather stations are sparse.
The present thesis aimed to explore the possibility of using NDVI as a potential drought indicator by studying anomaly patterns and correlations with other two climate variables, LST and precipitation. The study covered the growing season (March to September) of a fifteen year period, between 2000 and 2014, for Bayankhongor province in southwest Mongolia. The datasets used were MODIS NDVI, LST and TRMM Precipitation, which processing and analysis was supported by QGIS software and Python programming language. Monthly anomaly correlations between NDVI-LST and NDVI-Precipitation were generated as well as temporal correlations for the growing season for known drought years (2001, 2002 and 2009).
The results show that the three variables follow a seasonal pattern expected for a northern hemisphere region, with occurrence of the rainy season in the summer months. The values of both NDVI and precipitation are remarkably low while LST values are high, which is explained by the region’s climate and ecosystems. The NDVI average, generally, reached higher values with high precipitation values and low LST values. The year of 2001 was the driest year of the time-series, while 2003 was the wet year with healthier vegetation.
Monthly correlations registered weak results with low significance, with exception of NDVI-LST and NDVI-Precipitation correlations for June, July and August of 2002. The temporal correlations for the growing season also revealed weak results. The overall relationship between the variables anomalies showed weak correlation results with low significance, which suggests that an accurate answer for predicting drought using the relation between NDVI, LST and Precipitation cannot be given. Additional research should take place in order to achieve more conclusive results. However the NDVI anomaly images show that NDVI is a suitable drought index for Bayankhongor province.
25
Okyay, Ünal. "Evaluation of thermal remote sensing for detection of thermal anomalies as earthquake precursors: a case study for Malatya-Pütürge-Doganyol (Turkey) Earthquake, July 13, 2003." Master's thesis, 2012. http://hdl.handle.net/10362/8318.
Abstract:
Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.Several studies in last two decades indicated that presence of positive thermal anomalies associated with seismic activities can be detected by satellite thermal sensing methods. This study evaluates the potential of thermal remote sensing for detection of thermal anomalies prior to Malatya-Pütürge-Doğanyol (Turkey) earthquake using MODIS/Terra V5 LST/E (MOD11A1) data. In the previous studies, different methods based on different approaches have been suggested. In this particular study, four of the suggested methods were selected for evaluation as well as for comparison of different approaches. The analyses were carried out for fortnight before and after the earthquake. Depending on the method 4 to 7 years of daily daytime and nighttime MOD11A1 data were utilized. Furthermore, same set of analyses carried out for non-earthquake years as well as the earthquake year for the area. The results show that when only the earthquake year considered, all the methods used for the analyses detected the LST changes successfully and consistently not only before but also after the earthquake. However, thermal anomalies were not unique for the earthquake year and were also observed in the absence of seismic activity within defined time interval. Therefore, there exist no coherent evidence that indicates a direct link between the occurrence of seismic activity and the land surface temperature anomaly for Malatya-Pütürge-Doğanyol earthquake. Based on the information extracted, it can be said that, the reason for observing LST changes even in the absence of the seismic activity is the effect of environmental factors which have considerable influence on the methods and thus the detection of LST anomalies. Therefore, it can be said that since the effect of the Sun’s irradiation is minimal during night nighttime images would be more appropriate for thermal anomaly detection purpose. The findings support the argument that not every earthquake is preceded by detectable thermal precursor (Freund 2007; Saraf et al. 2009). On the other hand, not every LST anomaly is followed by an earthquake. Additionally, since the mechanism is not very well understood yet, it is not possible to identify earthquakes which would have thermal precursor prior to the incident. Therefore, it is concluded that utilizing LST anomalies based on satellite imagery for monitoring impending earthquake would not be adequate and feasible unless the mechanism of thermal precursors are very well understood.
26
"Advanced Processing of Multispectral Satellite Data for Detecting and Learning Knowledge-based Features of Planetary Surface Anomalies." Doctoral diss., 2019. http://hdl.handle.net/2286/R.I.55700.
Abstract:
abstract: The marked increase in the inflow of remotely sensed data from satellites have trans- formed the Earth and Space Sciences to a data rich domain creating a rich repository for domain experts to analyze. These observations shed light on a diverse array of disciplines ranging from monitoring Earth system components to planetary explo- ration by highlighting the expected trend and patterns in the data. However, the complexity of these patterns from local to global scales, coupled with the volume of this ever-growing repository necessitates advanced techniques to sequentially process the datasets to determine the underlying trends. Such techniques essentially model the observations to learn characteristic parameters of data-generating processes and highlight anomalous planetary surface observations to help domain scientists for making informed decisions. The primary challenge in defining such models arises due to the spatio-temporal variability of these processes.
This dissertation introduces models of multispectral satellite observations that sequentially learn the expected trend from the data by extracting salient features of planetary surface observations. The main objectives are to learn the temporal variability for modeling dynamic processes and to build representations of features of interest that is learned over the lifespan of an instrument. The estimated model parameters are then exploited in detecting anomalies due to changes in land surface reflectance as well as novelties in planetary surface landforms. A model switching approach is proposed that allows the selection of the best matched representation given the observations that is designed to account for rate of time-variability in land surface. The estimated parameters are exploited to design a change detector, analyze the separability of change events, and form an expert-guided representation of planetary landforms for prioritizing the retrieval of scientifically relevant observations with both onboard and post-downlink applications.Dissertation/Thesis
Doctoral Dissertation Computer Engineering 2019
27
Więczkowski, Krzysztof. "Non-carious lesions - characteristics, etiology, ways of treatment, occurrence." Master's thesis, 2019. http://hdl.handle.net/10284/8468.
Abstract:
As lesões dentárias não-cariosas são caracterizadas pela perda da estrutura dentária sem o envolvimento do processo carioso, podendo variar em função da sua etiologia, gravidade, localização e apresentação clínica (Yassin, 2000). Em consequência, pode-se observar o aparecimento de sensibilidade dentária, biofilme bacteriano, que pode comprometer a integridade estrutural do dente e a sua vitalidade pulpar. A frequência com que os profissionais de odontologia são confrontados com essas questões e como influenciam a qualidade de vida dos pacientes tornam este tipo de lesão o alvo deste trabalho.
Após a apresentação dos materiais e métodos escolhidos, questões de lesões não-cariosas em geral, mas também de lesões de etiologia traumática aguda e crônica. Em discussão, os diagnósticos são comparados, casos clínicos e tratamentos atuais são referenciados. Em conclusão, são sugeridas medidas que evitem essas doenças e, assim, promovam o bem-estar não apenas físico, mas também psicológico dos pacientes.Non-carious dental lesions are characterized by the loss of tooth structure without the involvement of the carious process, and may vary with regard to its etiology, severity, location and clinical presentation (Yassin, 2000). In consequence, the appearance of dental sensitivity, bacterial biofilm, may be observed, and may compromise the structural integrity of the tooth and its pulp vitality. The frequency with which dental practitioners are confronted with these questions and how they influence the quality of life of patients make this type of lesions the target of this work. After the presentation of the chosen materials and methods, questions of non-carious lesions in general, but also of injuries of acute and chronic traumatic etiology,. In discussion, the diagnoses are compared, clinical cases and current treatments are referenced. In conclusion are suggested measures that avoid these diseases and thus promote the well-being not only physical but also psychological of the patients.