Neste estudo é apresentado um procedimento de análise de dados magnéticos em casos de presença de magnetização remanente para, ao final do processo, a realização de uma inversão mais rápida e fiel ao comportamento do alvo em sub-superfície. O procedimento é composto por seis passos: (1) Delimitação lateral do alvo; (2) Estimativa de suas profundidades; (3) Estimativa das direções de inclinação e declinação aparentes de seu vetor de magnetização total; (4) Modelagem inicial com inferência de valores de susceptibilidades oriundos de estudos geológicos anteriores sobre o alvo e/ou sua região; (5) Inversão dos dados magnéticos utilizando o modelo inicial; e (6) atribuição das características magnéticas do passo (3) sobre o modelo de contraste de susceptibilidade magnética obtido com a inversão para a modelagem final do alvo, conhecendo-se seus vetores de magnetização induzida, total e, por subtração vetorial de ambos, remanente. Este procedimento foi aplicado a 108 casos sintéticos e a 8 casos reais pertencentes às províncias ígneas do Alto do Paranaíba e Rondoniana-San-Ignácio. Os resultados do uso deste procedimento indicaram uma recuperação das direções das componentes de magnetização com erro menor que 10%, em casos sintéticos, uma redução de mais de 20% no tempo de inversão com o uso de modelos iniciais, e qualitativamente, apresentaram modelos mais próximos dos originais (nos casos sintéticos) e geologicamente factíveis nos casos reais. / In this study, we present a procedure of analysis of magnetic data when remanence is present in order to, at the end of the process, obtain an inversion faster and more reliable inversion. The procedure is composed of six steps: (1) Estimation of the borders of the target; (2) Estimation of its depths; (3) A sweeping for the total apparent inclination and declination directions; (4) Initial modeling of a synthetic body, based on the recovered geometry and depth, on the directions of inclination and declination of the total magnetic field, and on previous analysis of the target and/or its region; (5) Inversion of magnetic data using the initial model; and (6) Attribution of the magnetic features of step (3) to the model recovered by the inversion for a final modeling of the target, estimating as well its remanent magnetization; the last through the vectorial resultant of the induction and total magnetization subtraction. This procedure was applied to 108 synthetic and to 8 real cases from the Alto do Paranaíba and Rondonian-San Ignacio Igneous Provinces. Their results pointed out that the error between the recovered directions of the magnetization components and the original values, in synthetic cases, was smaller than 10%; The inversions had their processing-time reduced in more than 20% and, qualitatively, presented models were more similar to the original (synthetic cases) and geologically feasible (real cases).

by Kim Hung Lo. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1988. / Bibliography: leaf 70.

No description available.

Accounting for azimuthal anisotropy is necessary for the processing and inversion of wide-azimuth and wide-aperture seismic data because wave speeds naturally depend on the wave propagation direction. Orthorhombic anisotropy is considered the most effective anisotropic model that approximates the azimuthal anisotropy we observe in seismic data. In the framework of full wave form inversion (FWI), the large number of parameters describing orthorhombic media exerts a considerable trade-off and increases the non-linearity of the inversion problem. Choosing a suitable parameterization for the model, and identifying which parameters in that parameterization could be well resolved, are essential to a successful inversion. In this thesis, I derive the radiation patterns for different acoustic orthorhombic parameterization. Analyzing the angular dependence of the scattering of the parameters of different parameterizations starting with the conventionally used notation, I assess the potential trade-off between the parameters and the resolution in describing the data and inverting for the parameters. In order to build practical inversion strategies, I suggest new parameters (called deviation parameters) for a new parameterization style in orthorhombic media. The novel parameters denoted ∈d, ƞd and δd are dimensionless and represent a measure of deviation between the vertical planes in orthorhombic anisotropy. The main feature of the deviation parameters consists of keeping the scattering of the vertical transversely isotropic (VTI) parameters stationary with azimuth. Using these scattering features, we can condition FWI to invert for the parameters which the data are sensitive to, at different stages, scales, and locations in the model. With this parameterization, the data are mainly sensitive to the scattering of 3 parameters (out of six that describe an acoustic orthorhombic medium): the horizontal velocity in the x1 direction, ∈1 which provides scattering mainly near the zero offset in the x1-x3 vertical plane, and ∈d, which is the ratio of the horizontal velocity squared in the x1 and x2 direction. Since, with this parameterization, the radiation pattern for the horizontal velocity is azimuth independent, we can perform an initial VTI inversion for two parameters (velocity and ∈1), then use ∈d to fit the azimuth variation in the data. This can be done at the reservoir level or any region of the model.

In this work the magnetic and magnetotelluric (MT) geophysical methods have been used to produce two 3D models for the Laver area in southern Norrbotten. A new discovery of a porphyry copper deposit located at the Lill-Laverberget was reported by Boliden in 2012. The goal with the models is to form a better understanding of the setting for the porphyry deposit and to see if any of the geophysical methods are suited to be used in exploration for it. For starters an edge detector (Beiki, 2010) was used on magnetic data to identify structures and petrological contacts in the area. The magnetic data was modelled using the SimPEG (Cocket, et al., 2015) inversion software to create a 3D model over the area. The Magnetic method quite clearly managed to resolve the volcanic units in the Laver area. MT data was collected during fieldwork in September of 2018 and modelled using the MOD3DEM (Egbert & Kelbert, 2012) inversion software. The MT model did not show any clear anomalies that could be related to the deposit. / I detta arbete så har de magnetiska och magnetotelluriska (MT) geofysiska metoderna används för att skapa två 3D modeller över Laverområdet i södra Norrbotten. I området finns en porfyrkopparfyndighet som Boliden rapporterade in 2012. Målet med båda modellerna är att fördjupa förståelsen för bildningsmiljön för fyndigheten och för att se hur lämpade de geofysiska metoderna är för prospektering. Det första steget var att använda befintliga magnetiska data och processa den med ED funktionen (Beiki, 2010) för att identifiera strukturer och bergartskontakter i området. Den magnetiska data användes för att producera en 3D modell med inversionsprogrammet SimPEG (Cocket, et al., 2015). Denna modell kunde skilja mellan vulkaniska och övriga bergarter i området. Magnetotelluriska data samlades in i september 2018 och modellerades med MOD3DEM (Egbert & Kelbert, 2012), denna modell hade dock problem att finna anomalier i området.

During wintertime temperature inversion episodes the concentrations of particulate air pollution, also defined as particulate matter (PM), in Utah’s Cache Valley have often been highest in the nation, with concentrations surpassing more populated and industrial areas. This has attracted much local and national attention to the area and its pollution. The Cache Valley has recently been declared to be in non-attainment of provisions of Federal law bringing to bear Federal regulatory attention as well. While there is epidemiological evidence indicating that PM is detrimental to public health, there is much less information indicating by which biological and molecular mechanisms PM can exert harm. This study was undertaken to better understand the mechanisms by which ambient PM collected in the Cache Valley can be harmful to human lung cells. Cache Valley PM was found to be mildly cytotoxic only at concentrations that were much greater than physiologically achievable, and such concentrations were difficult to obtain with the limited amounts of captured ambient PM. The limited cytotoxicity was despite apparent PM-induced pro-apoptotic signaling such as caspase-3 upregulation, and activation of caspase-12 and calpain. Cache Valley PM was found to be stressful to cells, triggering endoplasmic reticulum stress and the unfolded protein response. Cache Valley PM was also found to be inflammogenic leading to activation of pro-inflammatory transcription factors, increases in the release of pro-inflammatory cytokines and chemokines, as well as the upregulation of the activating receptors of these cytokines. The proinflammatory effects and absence of apoptosis, despite pro-apoptotic signaling of the Cache Valley PM on human lung cells appeared to stem from increased activation of the central pro-growth protein Akt with subsequent inactivation of the tumor suppressor P-TEN. These findings have indicated novel mechanisms of PM-related cellular stress and inflammation contributing needed information on what may be underlying mechanisms of PM associcated illnesses.

Cette thèse est consacrée à la représentation de la géométrie des images. Pour obtenir une représentation efficace il faut modéliser l'information géométrique et on construit des outils pour traiter ce modèle. Ces deux ingrédients vont de paire, s'influençant mutuellement pour obtenir un résultat satisfaisant, c'est à dire un modèle pertinent et des algorithmes rapides et performants.<br>On propose donc une modélisation géométrique des images, l'ambition étant de pouvoir extraire l'information contenue dans les images naturelles, c'est-à-dire les images qui nous entourent. Ce problème est bien sûr difficile car la géométrie des images est complexe et variable.

No description available.

Graduation date: 2000

The motivation to study this non-classical CMOS device is necessary to face with the ITRS constraints. In the ITRS roadmap, the gate length of devices are being scaled down rapidly but this rapid scaling is not in pace with the relatively slow scaling of the gate equivalent oxide thickness which leads to a degradation in the performance of the transistor. One of the solutions to this problem is the use of non-classical devices, such as the Gate-All-Around (GAA) MOSFET. Owing to the flexibility of SOI technology, these novel devices can be adapted to this technology bringing along with it the benefit of SOI technology. One of the main advantage of building this GAA device on SOI technology is that it offers the possibility whereby the second gate is easily built into the back of the device. GAA devices are also interesting because they do not need to scale down the thickness of the gate oxide rapidly but still able to maintain a suitable thickness to avoid problems such as current leakage through the thin gate oxide by tunnelling. The objective of this research can be divided into three parts; the first is to study the feasibility of the various fabrication process for this GAA device, the second to analyse the electrical characteristics of these fabricated GAA devices from DC characteristics up to 110 GHz and the third one is the use of commercial numerical simulation softwares (IE3D, Silvaco) in order to describe the physics of these novel devices. In this study, these different structures shows advantages and disadvantages when used in either analog or RF applications. The graded-channel structure has shown that it is advantageous when used in high performance analog circuits. The advantages of this structure is further enhanced when it is combined with the double-gate structure, forming a double-gate graded channel SOI MOSFET. Optimizing in terms of doping level along the channel of the graded-channel is important to yield good electrical results. In order for these devices to be successful commercially, it is important that they are compatible with the fabrication technology and trends available today and in the near future. To confirm that these devices can be adapted into today's and tomorrow's technology, we have shown that these they are easily adaptable in the current technology. Multiple-gate devices are a new group of devices which have been identified by ITRS as potential devices to meet the demands in the future. In this study, we have shown that these multiple-gate devices do indeed show improved short-channel effects and improved analog and RF characteristics when compared to the single-gate devices in existence. One of the main contributors to these improvements is due to what is known as the “volume inversion”.