Dissertations / Theses on the topic 'Magnetic prospecting – Data processing'
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Naudé, Corus. "Target selection from airborne magnetic and radiometric data in Steinhausen area, Namibia." Thesis, Rhodes University, 2012. http://hdl.handle.net/10962/d1001520.
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The eastern branch of the late Proterozoic Damara Orogenic Belt of central Namibia hosts various copper, gold, manganese and uranium deposits, but in the vicinity of Steinhausen, approximately 145 km northeast of Windhoek, the Damara Belt becomes increasingly covered by recent Kalahari cover sediments resulting in little known geology and subsequent lack of discovered economic mineral deposits. Airborne magnetic and radiometric data over the Steinhausen Study Area was enhanced through image processing and filtering to accentuate characteristics of subsurface geology that, by comparing these characteristics to known geology, aided in the interpretive mapping of lithology, structure and targets for follow-up exploration. As a result, some important observations regarding the regional lithology can be drawn. An arenaceous stratigraphic unit that includes a coarse grained, glassy quartzite below the Kuiseb Formation equates to either the eastern Damaran equivalent of the Nosib Group subjected to high grade metamorphism or, alternatively, the upper part of the pre-Damaran sequence, immediately underlying the Damara. The Kuiseb Formation within the study area is uncharacteristically varied as compared to the same formation further west along the Damaran Orogen and can be subdivided into 5 separate units based on geophysical signature. Structural features evident within the study area include the prominent Kudu and Okahandja Lineaments and straddle an area of inferred uplifted stratigraphy of possibly pre-Damara age. The Ekuja Dome (Kibaran age and host to the Omitiomire copper deposit) is also clearly discernible on the airborne magnetic data and is cross-cut by an east-northeast structural zone. Direct targets for follow-up exploration include the Rodenbeck intrusion, anomalous magnetic bodies and numerous radiometric anomalies present within the study area. Identified dome-like features are considered prospective for Omitiomire-style deposits and the Okatjuru Layered Complex is considered a possible source of copper, chromite, magnetite, ilmenite, nickel and the platinum group elements.
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Casto, Daniel W. "Calculating depths to shallow magnetic sources using aeromagnetic data from the Tucson Basin." Tucson, Ariz. : U.S. Dept. of the Interior, U.S. Geological Survey, 2001. http://geopubs.wr.usgs.gov/open-file/of01-505/.
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Jones, Jonathan A. "Nuclear magnetic resonance data processing methods." Thesis, University of Oxford, 1992. http://ora.ox.ac.uk/objects/uuid:7df97c9a-4e65-4c10-83eb-dfaccfdccefe.
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This thesis describes the application of a wide variety of data processing methods, in particular the Maximum Entropy Method (MEM), to data from Nuclear Magnetic Resonance (NMR) experiments. Chapter 1 provides a brief introduction to NMR and to data processing, which is developed in chapter 2. NMR is described in terms of the classical model due to Bloch, and the principles of conventional (Fourier transform) data processing developed. This is followed by a description of less conventional techniques. The MEM is derived on several grounds, and related to both Bayesian reasoning and Shannon information theory. Chapter 3 describes several methods of evaluating the quality of NMR spectra obtained by a variety of data processing techniques; the simple criterion of spectral appearance is shown to be completely unsatisfactory. A Monte Carlo method is described which allows several different techniques to be compared, and the relative advantages of Fourier transformation and the MEM are assessed. Chapter 4 describes in vivo NMR, particularly the application of the MEM to data from Phase Modulated Rotating Frame Imaging (PMRFI) experiments. In this case the conventional data processing is highly unsatisfactory, and MEM processing results in much clearer spectra. Chapter 5 describes the application of a range of techniques to the estimation and removal of splittings from NMR spectra. The various techniques are discussed using simple examples, and then applied to data from the amino acid iso-leucine. The thesis ends with five appendices which contain historical and philosophical notes, detailed calculations pertaining to PMRFI spectra, and a listing of the MEM computer program.
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Theodoridis, John Apostolis 1972. "Borehole electromagnetic prospecting for weak conductors." Monash University, School of Geosciences, 2004. http://arrow.monash.edu.au/hdl/1959.1/5225.
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Rydell, Joakim. "Advanced MRI Data Processing." Doctoral thesis, Linköping : Department of Biomedical Engineering, Linköpings universitet, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-10038.
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Bance, Simon G. "Data storage and processing using magnetic nanowires." Thesis, University of Sheffield, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505475.
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This thesis contains data from micromagnetic simulations that investigate new methods for data storage and processing on the nanoscale using ferromagnetic nanowires. First I consider a magnetic memory, domain wall trap memory, which could compete with a number of existing devices that are currently in widespread use. Domain wall trap memory exhibits a 90% lower coercivity over traditional MRAM designs because, instead of remagnetizing a rectangular or oval magnetic free layer by moment rotation or domain nucleation, an existing domain wall is moved along a structured nanowire to remagnetize part of the wire. I determine the fields for de-pinning, switching and expulsion of domain walls in memory cells to show that the margins between them can be sufficiently large for reliable operation. The nudged elastic band method is used to show that domain wall trap memory is thermally stable at room temperature.
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Ostroumov, Ivan Victorovich. "Magnetic field data processing with personal electronic device." Thesis, Polit. Challenges of science today: International Scientific and Practical Conference of Young Researchers and Students, April 6–8, 2016 : theses. – К., 2016. – 83p, 2016. http://er.nau.edu.ua/handle/NAU/26649.
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Maas, Luis C. (Luis Carlos). "Processing strategies for functional magnetic resonance imaging data sets." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/85262.
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Thesis (Ph.D.)--Harvard--Massachusetts Institute of Technology Division of Health Sciences and Technology, 1999.Includes bibliographical references (leaves 108-118).
by Luis Carlos Maas, III.
Ph.D.
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Rowe, Craig A. "A novel 3D transition zone seismic survey, Shoal Point, Port au Port Peninsula, Newfoundland : seismic data processing and interpretation /." Internet access available to MUN users only, 2003. http://collections.mun.ca/u?/theses,59416.
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Neukirch, Maik. "Non Stationary Magnetotelluric Data Processing." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/284932.
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Studies have proven that the desired signal for Magnetotellurics (MT) in the electromagnetic (EM) field can be regarded as 'quasi stationary' (i.e. sufficiently stationary to apply a windowed Fourier transform). However, measured time series often contain environmental noise. Hence, they may not fulfill the stationarity requirement for the application of the Fourier Transform (FT) and therefore may lead to false or unreliable results under methods that rely on the FT. In light of paucity of algorithms of MT data processing in the presence of non stationary noise, it is the goal of this thesis to elaborate a robust, non stationary algorithm, which can compete with sophisticated, state-of-the-art algorithms in terms of accuracy and precision. In addition, I proof mathematically the algorithm's viability and validate its superiority to other codes processing non stationary, synthetic and real MT data.
Non stationary EM data may affect the computation of Fourier spectra in unforeseeable manners and consequently, the traditional estimation of the MT transfer functions (TF). The TF estimation scheme developed in this work is based on an emerging nonlinear, non stationary time series analysis tool, called Empirical Mode Decomposition (EMD). EMD decomposes time series into Intrinsic Mode Functions (IMF) in the time-frequency domain, which can be represented by the instantaneous parameters amplitude, phase and frequency. In the first part of my thesis, I show that time slices of well defined IMFs equal time slices of Fourier Series, where the instantaneous parameters of the IMF define amplitude and phase of the Fourier Series parameters. Based on these findings I formulate the theorem that non stationary convolution of an IMF with a general time domain response function translates into a multiplication of the IMF with the respective spectral domain response function, which is explicitly permitted to vary over time. Further, I employ real world MT data to illustrate that a de-trended signal's IMFs can be convolved independently and then be used for further time-frequency analysis as done for MT processing.
In the second part of my thesis, I apply the newly formulated theorem to the MT method. The MT method analyses the correlation between the electric and magnetic field due to the conductivity structure of the subsurface. For sufficiently low frequencies (i.e. when the EM field interacts diffusively), the conductive body of the Earth acts as an inductive system response, which convolves with magnetic field variations and results in electric field variations. The frequency representation of this system response is commonly referred to as MT TF and its estimation from measured electric and magnetic time series is summarized as MT processing. The main contribution in this thesis is the design of the MT TF estimation algorithm based on EMD. In contrast to previous works that employ EMD for MT data processing, I (i) point out the advantages of a multivariate decomposition, (ii) highlight the possibility to use instantaneous parameters, and (iii) define the homogenization of frequency discrepancies between data channels. In addition, my algorithm estimates the transfer functions using robust statistical methods such as (i) robust principal component analysis and (ii) iteratively re-weighted least squares regression with a Huber weight function. Finally, TF uncertainties are estimated by iterating the complete robust regression, including the robust weight computation, by means of a bootstrap routine.
The proposed methodology is applied to synthetic and real data with and without non stationary character and the results are compared with other processing techniques. I conclude that non stationary noise can heavily affect Fourier based MT data processing but the presented non stationary approach is nonetheless able to extract the impedances correctly even when the other methods fail.
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Ogilvie, Jeffrey Scott. "Modeling of seismic coda, with application to attenuation and scattering in southeastern Tennessee." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/25871.
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Lee, Jae-Min. "Characterization of spatial and temporal brain activation patterns in functional magnetic resonance imaging data." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0013024.
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Davies, S. J. "Frequency-selective excitation and non-linear data processing in nuclear magnetic resonance." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233510.
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Mohammadi, Soroor. "Processing and Modeling of Gravity, Magnetic and Electromagnetic Data in the Falkenberg Area, Sweden." Thesis, Uppsala universitet, Geofysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-232714.
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Falkenberg area is located in southwest Sweden formed in the Sveconorwegian orogen and contains an extremely complex geological structure. Multiple geophysical datasets have been acquired and together with available petrophysical information, models corresponding to the subsurface geological structures were generated. The collected data comprise ground magnetic, AMT (Audio Magnetotelluric) and RMT (Radio Magnetotelluric) data. The available airborne magnetic and ground gravity data acquired by the Geological Survey of Sweden (SGU) as well as the reflection seismic section from a study made by Uppsala University further aids in obtaining substantially improved interpretation of the geometry of the structures along the AMT profile. The principal objective of this profile was to delineate and map the possible deformation zone crossed by the profile. The AMT study was expected to complement existing geophysical data and improve existing interpretations. The Ullared deformation zone contains decompressed eclogite facies rocks. The presented results were obtained by comparison of different geophysical methods along the profile. The susceptibility model and resistivity model show that eclogites have higher resistivity and susceptibility than the surrounding structures. However use of the Occam type of inversion on the AMT data, makes the resistivity model smoother than the susceptibility model and as a results it is difficult to estimate the dip of the structures. The AMT profile and the seismic section show the same dip direction (NE) for the eclogite bearing structures although due to the smoothing in the AMT model the dips seen in the seismic section cannot be recovered in the resistivity model.
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McLeish, Kate. "Combining data acquisition and post-processing techniques for magnetic resonance imaging of moving objects." Thesis, King's College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406105.
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Monnot, Cyril Gerard Valery. "Development of a data analysis platform for characterizing functional connectivity networks in rodents." Thesis, KTH, Skolan för teknik och hälsa (STH), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-124391.
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This document addresses the development and implementation of a routine for analyzing resting-state functional Magnetic Resonance Imaging (rs-fMRI) data in rodents. Even though resting-state connectivity is studied in humans already for several years with diverse applications in mental disorders or degenerative brain diseases, the interest for this modality is much more recent and less common in rodents. The goal of this project is to set an ensemble of tools in order to be able for the experimental MR team of KERIC to analyze rs-fMRI in rodents in a well defined and easy way. During this project several critical choices have been done, one of them is to use the Independent Component Analysis (ICA) in order to process the data rather than a seed-based approach. Also it was decided to use medetomidine as anesthesia rather than isoflurane for the experiments. The routine developed during this project was applied for a project studying the effects of running on an animal model of depression. The routine is composed of several steps, the preprocessing of the data mainly realized with SPM8, the processing using GIFT and the postprocessing which is some statistic tests on the results from GIFT in order to reveal differences between groups using the 2nd level analysis from SPM8 and the testing the correlations between components using the FNC toolbox.Detta dokument behandlar utvecklingen och implementeringen av en rutin för att analysera bilder från resting-state funktionell Magnetisk Resonenstomografi i gnagare. Även om resting-state connectivity studerats i människor i några år, med olika applikationer i psykiska störningar och neurodegenerativa sjukdomar, är intresset för detta område är betydligt nyare bland experimentell förskare som arbetar med gnagare. Målet av denna projekt är att inställa en procedur så att KERICs experimentell MR team kan lätt analysera resting-state funktionnell MRT data. Under denna projekt har olika viktiga val gjorts, en av dem är att använda Independent Component Analysis procedur för att analysera data framför en seed-baserad teknik. En andra var att använda för anestesi medetomidin och inte isofluran för experiment. Rutinen som var utvecklad under denna projekt blev användad på data från en projekt som studerar effekter av löpning på depression hos råttorna. Rutinen är delad i några delar, den första är att förbehandla data främst med SPM8, den andra är att använda GIFT för att behandla data och den sista är att testa statistiskt resultat från ICA med SPM8 och att testa korrelation mellan komponenter med FNC.
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Barron, Nicholas Henry. "An Analysis of an Advanced Software Business Model for Magnetic Resonance Imaging Data Post Processing." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1459422647.
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Saliaris, Ioannis R. "Real-Time data acquisition and processing of the Magnetic, Angular Rate and Gravity (MARG) sensor /." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FSaliaris.pdf.
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Thesis (M.S. in Electrical Engineering and M.S. in Systems Engineering)--Naval Postgraduate School, June 2004.Thesis advisor(s): Xiaoping Yun. Includes bibliographical references (p. 59-60). Also available online.
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Forshed, Jenny. "Processing and analysis of NMR data : Impurity determination and metabolic profiling." Doctoral thesis, Stockholm : Dept. of analytical chemistry, Stockholm university, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-712.
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Boogaart, Adrianus van den. "The use of signal processing algorithms to obtain biochemically relevant parameters from magnetic resonance data sets." Thesis, St George's, University of London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281778.
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Yang, Hsien-Min 1957. "PRINCIPAL COMPONENTS AND TEXTURE ANALYSIS OF THE NS-001 THEMATIC MAPPER SIMULATOR DATA IN THE ROSEMONT MINING DISTRICT, ARIZONA (GEOLOGIC, DIGITAL IMAGE PROCESSING, TEXTURE EXTRACTION)." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275436.
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Ramesh, Maganti V. "Magnetic stripe reader used to collect computer laboratory statistics." Virtual Press, 1990. http://liblink.bsu.edu/uhtbin/catkey/722464.
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This thesis is concerned with interfacing a magnetic stripe reader with an AT&T PC 6300 consisting of a 20 MB hard disk and with collecting laboratory usage statistics. Laboratory usage statistics includes the name and social security number of the student,along with other necessary details. This system replaces all manual modes of entering data, checks for typographical errors, renames the file containing a particular day's data to a file that has the current day's date as its new filename, and keeps track of the number of students for a particular day. This procedure will ensure security of laboratory equipment and can be modified for each computer laboratory on campus. The program results indicate an acceleration of data entry, favorable student response, and an increase in the accuracy of the data recorded.Department of Computer Science
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Friedmann, Arnon A. "Measurements, characterization, and system design for digital storage /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1997. http://wwwlib.umi.com/cr/ucsd/fullcit?p9732719.
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劉心雄 and Sum-hung Lau. "Adaptive FEM preprocessing for electro magnetic field analysis of electric machines." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31212451.
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拓也, 桑原, and Takuya Kuwahara. "Characterization of gas-liquid two-phase flow regimes using Magnetic fluid : setup, measurements, signal processing and data analysis." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB10268912/?lang=0, 2008. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB10268912/?lang=0.
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Derbyshire, John Andrew. "Echo-planar anemometry using conventional magnetic resonance imaging hardware." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364590.
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Lindemeyer, Johannes [Verfasser], Nadim Joni Akademischer Betreuer] Shah, and Achim [Akademischer Betreuer] [Stahl. "Optimisation of Phase Data Processing for Susceptibility Reconstruction in Magnetic Resonance Imaging / Johannes Lindemeyer ; Nadim Joni Shah, Achim Stahl." Aachen : Universitätsbibliothek der RWTH Aachen, 2015. http://d-nb.info/1128316560/34.
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Lindemeyer, Johannes Verfasser], Nadim Joni [Akademischer Betreuer] Shah, and Achim [Akademischer Betreuer] [Stahl. "Optimisation of Phase Data Processing for Susceptibility Reconstruction in Magnetic Resonance Imaging / Johannes Lindemeyer ; Nadim Joni Shah, Achim Stahl." Aachen : Universitätsbibliothek der RWTH Aachen, 2015. http://d-nb.info/1128316560/34.
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Hao, Jie. "A study on the application of independent component analysis to in vivo ¹H magnetic resonance spectra of childhood brain tumours for data processing." Thesis, University of Birmingham, 2010. http://etheses.bham.ac.uk//id/eprint/1064/.
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Independent component analysis (ICA) has the potential of automatically determining metabolite, macromolecular and lipid (MMLip) components that make up magnetic resonance (MR) spectra. However, the realiability with which this is accomplished and the optimal ICA approach for investigating in vivo MR spectra, have not yet been determined. A wavelet shrinkage de-noising based enhancement algorithm, utilising a newly derived relationship between the real and imaginary parts of the MR spectrum, is proposed. This algorithm is more robust compared with conventional de-noising methods. The two approaches for applying ICA, blind source separation (BSS) and feature extraction (FE), are thoroughly examined. A feature dimension selection method, which has not been adequately addressed, is proposed to set a theoretical guideline for ICA dimension reduction. Since the advantages and limitations of BSS-ICA and FE-ICA are different, combining them may compensate their disadvantages and lead to better results. A novel ICA approach involving a hybrid of the two techniques for automated decomposition of MRS dataset is proposed. It has been demonstrated that hybrid ICA provides more realistic individual metabolite and MMLip components than BSS-ICA or FE-ICA. It can aid metabolite identification and assignment, and has the potential for extracting biologically useful features and discovering biomarkers.
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Mori, Roberta Tomi 1988. "Integração de dados sísmicos 3D e de perfis geofísicos de poços para a predição da porosidade de um reservatório carbonático da Bacia de Campos." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287783.
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Orientador: Emilson Pereira LeiteDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências
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Resumo: Uma boa caracterização geológica dos reservatórios é de grande importância para a diminuição dos riscos da perfuração de um poço seco, assim como os custos de exploração e desenvolvimento de tal reservatório. No presente trabalho, buscou-se predizer os valores de porosidade de um reservatório através da integração de dados sísmicos 3D com perfis geofísicos de poços através de dois métodos: Regressão Linear Multiatributo e Redes Neurais Artificiais. O reservatório em questão é de constituição carbonática de origem Albiana, do final do Cretáceo Inferior. Na primeira etapa, foram traçados horizontes baseando-se em eventos sísmicos contínuos nas seções sísmicas, chamados superfícies cronoestratigráficas, no intervalo de profundidade que abrange o reservatório. Na segunda etapa, foram obtidos predições dos valores de porosidade do reservatório, assim como os respectivos modelos 3D, através dos dois métodos acima citados. Com a RLM, foram obtidos valores altos, baixos e intermediários de porosidade, variando desde 5% até 40%. Já com a RNA, tais valores variaram de 5% a 30%. Em ambos os métodos, os valores de porosidade apresentaram um crescimento da porção sudoeste em direção à porção nordeste, apresentando baixos valores nas profundidades referentes aos horizontes traçados. Picos com os valores máximos de porosidade foram observados em pontos dispersos por todo o volume 3D. Comparando-se os resultados obtidos pelos dois métodos, ficou evidente a maior eficácia da RNA, a qual apresentou correlação de 0,90 entre os valores reais e os valores preditos e erro de 2,86%, enquanto que os resultados obtidos através da RLM apresentou correlação de 0,55 e erro de 5,45%. Além disso, foi feita uma comparação com os aspectos geológicos do reservatório, na qual concluiu-se que as baixas porosidades da porção sudoeste se deve à presença de microporosidade e as altas porosidades da porção nordeste, à macroporosidade original das rochas. Concluiu-se também que as baixas porosidades encontradas nas regiões dos horizontes sísmicos estão relacionadas às diferentes texturas de rochas, já que as rochas presentes nessas regiões possuem maiores quantidades de matriz carbonática (packstones e wackestones) quando comparadas com as rochas das regiões entre os horizontes (grainstones)
Abstract: A good geological reservoirs characterization is very important for reducing the risk of drilling a dry hole as well as the costs for reservoir exploration and development. In this study, it was attempted to predict the porosity values of a reservoir through the integrations of 3D seismic data with geophysical well logs using two different methods: Multiattribute Linear Regression and Artificial Neural Networks. The studied reservoir has a carbonate composite, with the age of Albian, in late Early Cretaceous. On the first stage of the study, horizons have been traced based on continuous seismic events on seismic sections, in depths that cover the reservoir. On the second stage, it was obtained some predictions of reservoir porosity values, as well as their 3D models by the two methods that was already mentioned. High, low and intermediate porosity values have been obtained by the MLR, ranging from 5% to 40%. With the ANN, these values ranged from 5% to 30%. In both methods, the porosity values grew from south-west portion toward the northeast portion, with low values on the depths related to the horizons traced. We can observe maximum value peaks of porosity at points scattered throughout the 3D volume. A comparison of the results obtained by the two methods evidence the greater efficiency of the ANN, with a correlation of 0,90, between actual porosity and predicted values, and 2.86% of error, while the results obtained by the MLR showed a correlation of 0,55 and an error of 5.45%. Furthermore, we have made a comparison between the results obtained and the reservoir geological features, which allows us to conclude that the low porosity in the south-west portion is because of microporosity, while the high porosity in the northeast is because of the original macroporosity of the rocks. We also conclude that low porosity found on horizon surfaces are related to different rock textures, once the rocks on these horizon regions have more carbonatic matrix in their constitution (packstones and wackestones) than the rocks in the other regions between the horizons (grainstones)
Mestrado
Geologia e Recursos Naturais
Mestra em Geociências
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Remes, J. (Jukka). "Method evaluations in spatial exploratory analyses of resting-state functional magnetic resonance imaging data." Doctoral thesis, Oulun yliopisto, 2013. http://urn.fi/urn:isbn:9789526202228.
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Abstract Resting-state (RS) measurements during functional magnetic resonance imaging (fMRI) have become an established approach for studying spontaneous brain activity. RS-fMRI results are often obtained using explorative approaches like spatial independent component analysis (sICA). These approaches and their software implementations are rarely evaluated extensively or specifically concerning RS-fMRI. Trust is placed in the software that they will work according to the published method descriptions. Many methods and parameters are used despite the lack of test data, and the validity of the underlying models remains an open question. A substantially greater number of evaluations would be needed to ensure the quality of exploratory RS-fMRI analyses. This thesis investigates the applicability of sICA methodology and software in the RS-fMRI context. The experiences were used to formulate general guidelines to facilitate future method evaluations. Additionally, a novel multiple comparison correction (MCC) method, Maxmad, was devised for adjusting evaluation results statistically. With regard to software considerations, the source code of FSL Melodic, popular sICA software, was analyzed against its published method descriptions. Unreported and unevaluated details were found, which implies that one should not automatically assume a correspondence between the literature and the software implementations. The method implementations should rather be subjected to independent reviews. An experimental contribution of this thesis is that the credibility of the emerging sliding window sICAs has been improved by the validation of sICA related preprocessing procedures. In addition to that, the estimation accuracy regarding the results in existing RS-fMRI sICA literature was also shown not to suffer even though repeatability tools like Icasso have not been used in their computation. Furthermore, the evidence against conventional sICA model suggests the consideration of different approaches to analysis of RS-fMRI. The guidelines developed for facilitation of evaluations include adoption of 1) open software development (improved error detection), 2) modular software designs (easier evaluations), 3) data specific evaluations (increased validity), and 4) extensive coverage of parameter space (improved credibility). The proposed Maxmad MCC addresses a statistical problem arising from broad evaluations. Large scale cooperation efforts are proposed concerning evaluations in order to improve the credibility of exploratory RS-fMRI methodsTiivistelmä Aivoista toiminnallisella magneettikuvantamisella (engl. functional magnetic resonance imaging, fMRI) lepotilassa tehdyt mittaukset ovat saaneet vakiintuneen aseman spontaanin aivotoiminnan tutkimuksessa. Lepotilan fMRI:n tulokset saadaan usein käyttämällä exploratiivisia menetelmiä, kuten spatiaalista itsenäisten komponenttien analyysia (engl. spatial independent component analysis, sICA). Näitä menetelmiä ja niiden ohjelmistototeutuksia evaluoidaan harvoin kattavasti tai erityisesti lepotilan fMRI:n kannalta. Ohjelmistojen luotetaan toimivan menetelmäkuvausten mukaisesti. Monia menetelmiä ja parametreja käytetään testidatan puuttumisesta huolimatta, ja myös menetelmien taustalla olevien mallien pätevyys on edelleen epäselvä asia. Eksploratiivisten lepotilan fMRI-datan analyysien laadun varmistamiseksi tarvittaisiin huomattavasti nykyistä suurempi määrä evaluaatioita. Tämä väitöskirja tutki sICA-menetelmien ja -ohjelmistojen soveltuvuutta lepotilan fMRI-tutkimuksiin. Kokemuksien perusteella luotiin yleisiä ohjenuoria helpottamaan tulevaisuuden menetelmäevaluaatioita. Lisäksi väitöskirjassa kehitettiin uusi monivertailukorjausmenetelmä, Maxmad, evaluaatiotulosten tilastolliseen korjaukseen. Tunnetun sICA-ohjelmiston, FSL Melodicin, lähdekoodi analysoitiin suhteessa julkaistuihin menetelmäkuvauksiin. Analyysissa ilmeni aiemmin raportoimattomia ja evaluoimattomia menetelmäyksityiskohtia, mikä tarkoittaa, ettei kirjallisuudessa olevien menetelmäkuvausten ja niiden ohjelmistototeutusten välille pitäisi automaattisesti olettaa vastaavuutta. Menetelmätoteutukset pitäisi katselmoida riippumattomasti. Väitöskirjan kokeellisena panoksena parannettiin liukuvassa ikkunassa suoritettavan sICA:n uskottavuutta varmistamalla sICA:n esikäsittelyjen oikeellisuus. Lisäksi väitöskirjassa näytettiin, että aiempien sICA-tulosten tarkkuus ei ole kärsinyt, vaikka niiden estimoinnissa ei ole käytetty toistettavuustyökaluja, kuten Icasso-ohjelmistoa. Väitöskirjan tulokset kyseenalaistavat myös perinteisen sICA-mallin, minkä vuoksi tulisi harkita siitä poikkeavia lähtökohtia lepotilan fMRI-datan analyysiin. Evaluaatioiden helpottamiseksi kehitetyt ohjeet sisältävät seuraavat periaatteet: 1) avoin ohjelmistokehitys (parantunut virheiden havaitseminen), 2) modulaarinen ohjelmistosuunnittelu (nykyistä helpommin toteutettavat evaluaatiot), 3) datatyyppikohtaiset evaluaatiot (parantunut validiteetti) ja 4) parametriavaruuden laaja kattavuus evaluaatioissa (parantunut uskottavuus). Ehdotettu Maxmad-monivertailukorjaus tarjoaa ratkaisuvaihtoehdon laajojen evaluaatioiden tilastollisiin haasteisiin. Jotta lepotilan fMRI:ssä käytettävien exploratiivisten menetelmien uskottavuus paranisi, väitöskirjassa ehdotetaan laaja-alaista yhteistyötä menetelmien evaluoimiseksi
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Abufadel, Amer Y. "4D Segmentation of Cardiac MRI Data Using Active Surfaces with Spatiotemporal Shape Priors." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14005.
Full textAbstract:
This dissertation presents a fully automatic segmentation algorithm for cardiac MR data. Some of the currently published methods are
automatic, but they only work well in 2D and sometimes in 3D and do not perform well near the extremities (apex and base) of the heart.
Additionally, they require substantial user input to make them feasible for use in a clinical environment. This dissertation introduces
novel approaches to improve the accuracy, robustness, and consistency of existing methods.
Segmentation accuracy can be improved by knowing as much about the data as possible. Accordingly, we compute a single 4D active surface
that performs segmentation in space and time simultaneously. The segmentation routine can now take advantage of information from
neighboring pixels that can be adjacent either spatially or temporally.
Robustness is improved further by using confidence labels on shape priors. Shape priors are deduced from manual
segmentation of training data. This data may contain imperfections that may impede proper manual segmentation. Confidence
labels indicate the level of fidelity of the manual segmentation to the actual data. The contribution of regions with low
confidence levels can be attenuated or excluded from the final result.
The specific advantages of using the 4D segmentation along with shape priors and regions of confidence are highlighted throughout the
thesis dissertation. Performance of the new method is measured by comparing the results to traditional 3D segmentation and to manual
segmentation performed by a trained clinician.
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Agnoletto, Ethiane 1988. "Caracterização litológica e identificação de alvos exploratórios na região de Flor da Serra, Província Aurífera Alta Floresta (MT), utilizando dados magnéticos e geoelétricos." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287296.
Full textAbstract:
Orientadores: Emilson Pereira Leite, Antônio João Paes de BarrosDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências
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Resumo: A região garimpeira de Flor da Serra situa-se na porção Leste da Província Aurífera Alta Floresta, Norte do Mato Grosso, inserida no contexto geológico da porção Centro-Sul do Cráton Amazônico, constituída por suítes plutono-vulcânicas de idade paleoproterozóica e coberturas sedimentares associadas. Várias ocorrências de ouro estão dispostas em grandes zonas de descontinuidade crustal que delimitam terrenos geocronológicos e geológicos. O expressivo adensamento de corpos filoneanos e o histórico de produção destaca essa região de expressivo potencial exploratório. Neste contexto, o trabalho teve por objetivo a identificação de novos alvos exploratórios por meio da análise de dados geofísicos, descrição de testemunhos de sondagem e mapeamento de cavas garimpeiras. A integração desses dados contribuiu em especial à evolução do conhecimento geológico da região Flor da Serra, e também de maneira geral para o setor leste da PAAF. A área de estudo está inserida na Suíte Intrusiva Flor da Serra, que é constituída eminentemente por gabros, dioritos a monzogabros, entretanto com o mapeamento de cavas garimpeiras e descrição de furos de sondagem, verificou-se a existência de quatro unidades geológicas principais: (i) Granitóides do Embasamento de composição tonalítica a granodiorítica com associação de magnetita + granada, intrudidos por rochas da (ii) Unidade Granodiorítica a Tonalítica de mesma composição. Essa unidade é truncada por (iii) Diques Máficos a Intermediários e localmente há presença de (iv) Rochas Cataclásticas a Miloníticas. Os litotipos foram variavelmente afetados por sete tipos de alteração hidrotermal (ordem temporal): (i) alteração potássica intensa, (ii) silicificação pervasiva, (iii) carbonatação, (iv) alteração com muscovita, (v) propilitização mais pontual, (vi) alteração Quartzo-Sericita-Pirita (QSP) com substituição total da rocha e, (vii) vênulas de calcita tardias. Foram realizados levantamentos geofísicos utilizando métodos geoelétricos (Polarização Induzida/Resistividade - IP/RES) e magnetometria em escala de depósito. Valores anômalos de cargabilidade e resistividade obtidos após aplicação de um algoritmo de inversão com vínculo de suavidade definiram zonas de intensa silicificação e de QSP. Essas zonas estão diretamente relacionadas a um minério do tipo disseminado, além de terem possibilitado a delimitação da interface saprólito-rocha sã (manto intempérico profundo de até 50 m). Para facilitar a interpretação geológica, foram gerados mapas do campo magnético anômalo reduzido ao equador magnético e da amplitude do sinal analítico. Esse último possibilitou a definição de um stock granítico intrusivo no embasamento heterogêneo. Para eliminar ruídos remanescentes nos mapas de anomalias magnéticas, foram aplicados os filtros cosseno direcional e continuação para cima, com geração de mapa que confirmou o padrão estrutural vigente no Sistema Flor da Serra. Essa estruturação está associada à diferentes níveis crustais, balizam os principais corpos filoneano da região e também estão associadas a alteração QSP. A integração dos principais lineamentos estruturais; bolsões de alta cargabilidade e resistividade; mapeamento detalhado de cavas desativadas e zona de borda da intrusão possibilitou a definição de pontos de interesse prospectivo metalogenético
Abstract: The gold mining area of Flor da Serra is located in the East portion of the Alta Floresta Gold Province (PAAF), North of the state of Mato Grosso, inserted into the geological context of the South-Central portion of the Amazon Craton, which comprises plutono-Paleoproterozoic volcanic suites and associated sedimentary cover. Several gold occurrences are arranged in large zones of crustal discontinuities demarcating land geochronological and geological. The significant densification of filoneano bodies and production history highlights the significant exploration potential of the area. In this context, this study aimed to identify new exploration targets through analysis of geophysical data, description of drill core samples and prospecting pits. The integrated analysis of these data contributed in particular to the development of the geological knowledge of Flor da Serra, and also generally for the eastern sector of the PAAF. The study area covers the Intrusive Suite Flor da Serra which consists essentially of gabbros, diorites to monzogabros, however mapping of prospecting pits and description of borehole samples confirmed the existence of at least four main geological units: (i) granitoids in Basement of tonalitic to granodioritic composition association with magnetite + garnet rocks intruded by (ii) granodioritic to tonalitic of the same composition. This unit is truncated by (iii) the Intermediate Mafic Dykes and locally by (iv) cataclastic to mylonitic rocks. Rocks of the Flor da Serra have been affected by the following hydrothermal alteration types (temporal sequence): (i) intense potassic alteration, (ii) pervasive silicification, (iii) carbonation, (iv) alteration with muscovite, (v) punctual propylitization, (vi) Quartz-Sericite-Pyrite (QSP) alteration with total replacement of the rock and (vii) late calcite veinlets. The geophysical survey consisted of the application of geoelectrical methods (Induced Polarization/Resistivity - IP/RES) and magnetometry at deposit scale. Anomalous values of chargeability and resistivity allowed defining zones of intense silicification and QSP closely related to a disseminated ore type, beyond the boundaries of the saprolite-bedrock interface (deep weathering mantle of up to 50 m). To facilitate geological interpretation, maps of the magnetic anomalous field reduced to the magnetic equador and the analytic signal amplitude were generated. The latter allowed the identification of granitic intrusive stock in heterogeneous basement. To improve the final product and eliminate remaining noise cosine directional filter and upward continuation to 100 m were applied, providing a map which confirmed the structural pattern prevailing in the Flor da Serra system. This structural system is associated with different crustal levels, controls the main filoneano bodies of the region and is attached to QSP alteration. The integration of the main structural lineaments; zones of high chargeability/resistivity; detailed mapping of deactivated pits; and boundary zone of the intrusion led to the definition of prospective metallogenic targets
Mestrado
Geologia e Recursos Naturais
Mestra em Geociências
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Herterich, Rebecka, and Anna Sumarokova. "Coil Sensitivity Estimation and Intensity Normalisation for Magnetic Resonance Imaging." Thesis, KTH, Medicinteknik och hälsosystem, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-263149.
Full textAbstract:
The quest for improved efficiency in magnetic resonance imaging has motivated the development of strategies like parallel imaging where arrays of multiple receiver coils are operated simultaneously in parallel. The objective of this project was to find an estimation of phased-array coil sensitivity profiles of magnetic resonance images of the human body. These sensitivity maps can then be used to perform an intensity inhomogeneity correction of the images. Through investigative work in Matlab, a script was developed that uses data embedded in raw data from a magnetic resonance scan, to generate coil sensitivities for each voxel of the volume of interest and recalculate them to two-dimensional sensitivity maps of the corresponding diagnostic images. The resulting mapped sensitivity profiles can be used in Sensitivity Encoding where a more exact solution can be obtained using the carefully estimated sensitivity maps of the images.Inom magnetresonanstomografi eftersträvas förbättrad effektivitet, villket bidragit till utvecklingen av strategier som parallell imaging, där arrayer av flera mottagarspolar andvänds samtidigt. Syftet med detta projekt var att uppskattamottagarspolarnas känslighetskarta för att utnyttja dem till i metoder inom magnetresonansavbildning. Dessa känslighetskartor kan användas för att utföra intensitetsinhomogenitetskorrigering av bilderna. Genom utforskande arbete i Matlab utvecklades ett skript som tillämpar inbyggd rådata, från en magnetiskresonansavbildning för att generera spolens känslighet för varje voxel av volymen och omberäkna dem till tvådimensionella känslighetskartor av motsvarande diagnostiska bilder. De resulterande kartlagda känslighetsprofilerna kan användas i känslighetskodning, där en mer exakt lösning kan erhållas med hjälp av de noggrant uppskattade känslighetskartorna.
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Vinhas, Maria Cecilia Sodero 1968. "Aplicação de métodos geofísicos aplicados em pontos selecionados do Estuário do Rio Itanhaém." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/286645.
Full textAbstract:
Orientador: Sueli Yoshinaga Pereira, Rodrigo de Souza PortugalTese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências
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Resumo: Essa pesquisa objetivou a aplicação e o entendimento da relação de três métodos geofísicos: eletrorresistividade, sísmica de refração e sismoelétrica; em pontos selecionados no Estuário do Rio Itanhaém e se eles podem ser validados pelas informações geológicas e hidrogeológicas da região. Os levantamentos foram realizados em duas etapas. A primeira etapa foi o de reconhecimento de campo, realizado no período de 21 a 26 de setembro/2009 que é considerado um período menos chuvoso. Os pontos escolhidos foram denominados de Ponto Praia, Ponto Chácara, Ponto Lixão e Ponto Country Club. A segunda etapa consistiu na coleta de dados propriamente dita nos pontos Chácara, Lixão e Country Club; o ponto Praia foi excluído por estar próximo às grandes torres de transmissão de energia, fazendo com que houvesse interferência nos dados. No ponto Lixão foi verificada a existência de gás metano, na superfície, através das bolhas de ar nas poças de água, no Ponto Country se localizava próximo a dois brejos e um pequeno córrego, e por fim o Ponto Chácara se localizava próximo ao Rio Branco, onde foi possível perceber a influência do aquífero livre na coleta dos dados. O período da segunda etapa dos levantamentos de dados ocorreu entre setembro de 2010 e agosto de 2011. Os levantamentos resultaram em um perfil vertical central, dos pontos selecionados, onde foram encontrados os seguintes materiais: areia, sedimentos arenosos, areia argilosa, argila seca, dois tipos de aquífero (de água doce e de água salobra), além de solos saturados e não saturados, e lixo. Em alguns levantamentos atingiram a rocha sã. Os levantamentos eletrorresistivos foram os que tiveram melhor resultado, os levantamentos de sísmica obtiveram uma camada apenas em quase todos os levantamentos, sendo que em um deles, o segundo campo do Ponto Country Club, se obteve mais de uma camada de material. Os levantamentos sismoelétricos não tiveram seus tratamentos finalizados, pois se percebeu que era necessária a utilização pré-amplificador; sua ausência no levantamento no campo, aliado a presença de linhas elétricas nos locais do levantamento, prejudicou nos resultados dos dados coletados, fato indicado pela presença das linhas harmônicas nos dados, e consequentemente não ter finalizado o algoritmo de tratamento desses dados
Abstract: This research intended the application and understanding about connexion among three geophysical methods: eletrical resistivity, refraction seismic and eletrical seismic; in selected places along Itanhaem River Estuary and if they can be accepted by geological and hydrogeological information of the region. The survey was accomplished in two phases. The first one was to recognize field of study, which was realized from 21st to 26th of September 2009, that is considered a less rainy season. The chosen sites were: Praia Point, Chácara Point, Lixão Point and Country Club Point. The second phase was the data collection, at these chosen sites, Chácara, Lixão and Country Club; The Praia Point was excluded because it was very near of large power transmission towers and it was causing interference in the collected information, at the Lixão Point was verified existence of methane, on the surface, through the air bubbles in puddles, in the case of Country Club Point was located near two swamps and a small stream, the Ranch Point was located near the river called Branco, and it was possible to realized the free influence of this aquifer in data collection. The second phase period of data collection, occurred between September 2010 and August 2011. The surveys resulted in a central vertical shape of the selected sites, where the following materials were found sand, sandy sediments, clayey sand, dry clay, two types of groundwater (freshwater and brackish water), and saturated and unsaturated soils and waste. In some surveys reached the bedrock. The electrical resistivity surveys were those who obtained better results, the seismic surveys obtained only a layer in almost all surveys, and in one of them, the second Country Club Point, got more than one layer of material. The electrical seismic surveys were not their treatments finalized, because it was realized the need to use a preamplifier; its absence in the field survey, combined with the presence of power lines in the survey sites, affected the collected data results, condition indicated by the presence of harmonic lines in the data, and consequently have not finalized these data processing algorithm
Doutorado
Geologia e Recursos Naturais
Doutora em Ciências
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Tang, Shijun. "Investigation on Segmentation, Recognition and 3D Reconstruction of Objects Based on LiDAR Data Or MRI." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc801920/.
Full textAbstract:
Segmentation, recognition and 3D reconstruction of objects have been cutting-edge research topics, which have many applications ranging from environmental and medical to geographical applications as well as intelligent transportation. In this dissertation, I focus on the study of segmentation, recognition and 3D reconstruction of objects using LiDAR data/MRI. Three main works are that (I). Feature extraction algorithm based on sparse LiDAR data. A novel method has been proposed for feature extraction from sparse LiDAR data. The algorithm and the related principles have been described. Also, I have tested and discussed the choices and roles of parameters. By using correlation of neighboring points directly, statistic distribution of normal vectors at each point has been effectively used to determine the category of the selected point. (II). Segmentation and 3D reconstruction of objects based on LiDAR/MRI. The proposed method includes that the 3D LiDAR data are layered, that different categories are segmented, and that 3D canopy surfaces of individual tree crowns and clusters of trees are reconstructed from LiDAR point data based on a region active contour model. The proposed method allows for delineations of 3D forest canopy naturally from the contours of raw LiDAR point clouds. The proposed model is suitable not only for a series of ideal cone shapes, but also for other kinds of 3D shapes as well as other kinds dataset such as MRI. (III). Novel algorithms for recognition of objects based on LiDAR/MRI. Aimed to the sparse LiDAR data, the feature extraction algorithm has been proposed and applied to classify the building and trees. More importantly, the novel algorithms based on level set methods have been provided and employed to recognize not only the buildings and trees, the different trees (e.g. Oak trees and Douglas firs), but also the subthalamus nuclei (STNs). By using the novel algorithms based on level set method, a 3D model of the subthalamus nuclei (STNs) in the brain has been successfully reconstructed based on the statistical data of previous investigations of an anatomy atlas as reference. The 3D rendering of the subthalamic nuclei and the skull directly from MR imaging is also utilized to determine the 3D coordinates of the STNs in the brain. In summary, the novel methods and algorithms of segmentation, recognition and 3D reconstruction of objects have been proposed. The related experiments have been done to test and confirm the validation of the proposed methods. The experimental results also demonstrate the accuracy, efficiency and effectiveness of the proposed methods. A framework for segmentation, recognition and 3D reconstruction of objects has been established, which has been applied to many research areas.
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Lee, Thomas Seward. "Software-based gradient nonlinearity distortion correction." CSUSB ScholarWorks, 2006. https://scholarworks.lib.csusb.edu/etd-project/3180.
Full textAbstract:
The primary purpose of the thesis is to discuss the use of Magnetic Resonance Imaging (MRI) in functional proton radiosurgery. The methods presented in this thesis were specifically designed to correct gradient nonlinearity distortion, the single greatest hurdle that limits the deployment of MRI-based functional proton radiosurgery systems. The new system central in the thesis fully utilized MRI to provide localization of anatomical targets with submillimeter accuracy. The thesis provides analysis and solutions to the problems related to gradient nonlinearity distortion. The characteristics of proton radiosurgery are introduced, in addition to a discussion of its advantages over other current methods of radiation oncology. A historical background for proton radiosurgery is also presented, along with a description of its implementation at Loma Linda University Medical Center (LLUMC), where a new system for functional proton radiosurgery has been proposed and is currently under development.
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Pareilh-Peyrou, Mathias. "Optimisation des méthodes à induction électromagnétique pour l'ingénierie des sols." Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22781/document.
Full textAbstract:
Le travail de recherche présenté dans ce mémoire de thèse, qui s’est déroulée dans le cadre d’un dispositif CIFRE (Conventions Industrielles de Formation par la Recherche) en collaboration avec le pôle géophysique du CEBTP à clermont-ferrand et le laboratoire Magmas et Volcans de l’UCA. Ce travail porte sur l’amélioration du rendement de la méthode géophysique électromagnétique de sub-surface. L’idée est de parvenir à extraire plus d’informations à partir des données électromagnétiques en gardant une méthode de prospection proche des méthodes classiques actuelles. Les techniques électromagnétiques (EM) sont des méthodes géophysiques fondées sur la mesure des variations de champs magnétiques et sont utilisé pour réaliser des mesures des caractéristiques électriques des sols. Ces appareils EM sont dits inductifs et ne nécessitent donc pas de contact avec le sol. Ils peuvent donc être mis en œuvre avec une vitesse d’acquisition plus importante que la plupart des autres méthodes géophysiques (profils électriques, gravimétrie, sismique...).Dans le cadre de ce travail, différents développements ont été effectués pour répondre à la problématique de l’amélioration des outils de prospection EM. La prospection sur le terrain a été améliorée grâce au développement d’un prototype de système d’acquisition automatisé. Celui ci est composé d’un conductivimètre (EM-31), d’un chariot support en fibre de verre, d’un GPS et d’un ordinateur assurant un enregistrement continu et géo-référencé des données à l’aide d’un programme spécialement conçu en Python.Ce mémoire présente également une procédure de correction des valeurs du conductivimètre EM-31, notamment la correction des effets de la hauteur de l’appareil par rapport au sol.Un programme Matlab a également spécifiquement été conçu pour le traitement automatisé de données EM. Ce programme permet de disposer rapidement des outils de base pour le traitement et la bonne visualisation des données.Deux études de cas ont été réalisées dans le cadre de ce travail doctoral.La première concerne une prospection linéaire d’une centaine de kilomètres sur des digues de protection contre les crues le long du fleuve Loire. Cette étude met en évidence les difficultés rencontrées lors d’une prospection de grande envergure et permet d’identifier les problématiques d’une étude géophysique à grande échelle, notamment la gestion du grand nombre de données. Cela contraint le choix de la méthodologie de prospection et permet de mettre en place les procédures d’automatisation des traitements.La seconde étude concerne la mise en œuvre des outils EM sur des terrains de nature volcanique. La prospection EM a su s’avérer très efficace pour la cartographie de nombreux sites archéologiques. Cependant les sols et les roches en région volcaniques sont connus pour avoir des effets magnétiques forts. Il s’agit ici dans le cadre d’une prospection archéologique, de déterminer plus précisément les effets magnétiques du sous-sol sur la mesure EMThis study has been conducted in the framework of the CIFRE doctoral contract, in collaboration with the Ginger CEBTP Geophysics pole and the “Laboratoire Magmas et Volcans”. The main objective of this work is to improve the performance of the sub-surface electromagnetic induction method.The principle is to retrieve more information from electromagnetic data keeping a prospecting method close to current field methods. Electromagnetic (EM) methods are based upon magnetic fields variations in order to to measure electrical characteristics of soils. EM devices are inductive and so don’t need contact with the ground. Thus they can be implemented faster than most of others geophysical methods (seismic, electrical profiles, gravimetry). In this framework, several developments have been performed to respond to the improvement of EM prospecting methods. The field survey was improved by the development of an automated acquisition system including a conductivimeter (EM-31) mounted on a fibreglass cart with a GPS receiver and a computer running a special Python program which ensure continuous data recording and geo-reference. In this thesis we present a correction procedure for the EM-31 conductivimeter values, in particular the device height above the ground. A Matlab program was also specifically conceived for automated EM data processing. It combines basic data processing and visualization tools. Two case studies was conducted during this doctoral work. The first one is about a hundred kilometers of linear prospecting along the Loire protection dykes (France). This study highlights the difficulties of large scale geophysical prospecting and allows to identify specific issues such as management of large data number. This influence the prospecting methodology and allows implementation of adapted automatized data processing. The second case study is about the implementation of EM devices on volcanic fields. Several archaeological sites has been mapped using EM methods. However in volcanic regions, soils and rocks are known to have strong magnetic effects. In this specific case of an archaeological study the purpose is to determine precisely the magnetic effects of soils on EM measures
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Neumann, Markus. "Automatic multimodal real-time tracking for image plane alignment in interventional Magnetic Resonance Imaging." Phd thesis, Université de Strasbourg, 2014. http://tel.archives-ouvertes.fr/tel-01038023.
Full textAbstract:
Interventional magnetic resonance imaging (MRI) aims at performing minimally invasive percutaneous interventions, such as tumor ablations and biopsies, under MRI guidance. During such interventions, the acquired MR image planes are typically aligned to the surgical instrument (needle) axis and to surrounding anatomical structures of interest in order to efficiently monitor the advancement in real-time of the instrument inside the patient's body. Object tracking inside the MRI is expected to facilitate and accelerate MR-guided interventions by allowing to automatically align the image planes to the surgical instrument. In this PhD thesis, an image-based workflow is proposed and refined for automatic image plane alignment. An automatic tracking workflow was developed, performing detection and tracking of a passive marker directly in clinical real-time images. This tracking workflow is designed for fully automated image plane alignment, with minimization of tracking-dedicated time. Its main drawback is its inherent dependence on the slow clinical MRI update rate. First, the addition of motion estimation and prediction with a Kalman filter was investigated and improved the workflow tracking performance. Second, a complementary optical sensor was used for multi-sensor tracking in order to decouple the tracking update rate from the MR image acquisition rate. Performance of the workflow was evaluated with both computer simulations and experiments using an MR compatible testbed. Results show a high robustness of the multi-sensor tracking approach for dynamic image plane alignment, due to the combination of the individual strengths of each sensor.
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Junior, Pedro Paulo de Magalhães Oliveira. "Medida da espessura cortical com imagens de ressonância magnética: técnica e aplicações na doença de Alzheimer e na polimicrogiria." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/5/5151/tde-09062009-120039/.
Full textAbstract:
As técnicas de morfometria baseadas em imagens ressonância magnética desde o início do século XXI tem sido uma importante ferramenta para estudar doenças neurológicas. Um dos benefícios desta técnica é prover medidas de parâmetros que manualmente são difíceis de estimar e com um grande viés de operador. Este trabalho teve como objetivo descrever as alterações corticais em duas doenças, uma malformação do desenvolvimento cortical, e outra neurodegenerativa utilizando as técnicas de morfometria por estudo de superfície cortical. As imagens de ressonância magnética foram obtidas por sequências volumétricas ponderadas em T1 e analisadas através de um algoritmo específico, implementado no software FreeSurfer (Fischl et al., Harvard University - Estados Unidos). De um grupo de pacientes com malformação do desenvolvimento cortical foram analisados 3 pacientes com polimicrogiria (PMG), comparados com um grupo de 14 pessoas saudáveis e de idade similar. Foram também analisados 14 pacientes com alteração degenerativa (Doença de Alzheimer - DA) com manifestação recente, idade avançada e alto nível de escolaridade comparados com 20 idosos saudáveis. Este dado foi posteriormente utilizado para separar os dois grupos através de uma técnica de classificação multivariada, implementada pelo autor. A análise de cada um dos indivíduos com PMG comparados ao grupo controle apresentou aumento de espessura cortical nas áreas com polimicrogiria e redução também estatisticamente significante de espessura cortical em áreas sem polimicrogiria. No estudo do grupo de pacientes com DA observou-se redução de espessura cortical nas regiões do córtex para hipocampal, entorrinal, córtex límbico e córtex temporal superior. Além disso, a volumetria de estruturas subcorticais obtidas apresentou poder de classificação de 84,6% na comparação de pacientes com DA e controles saudáveis. Concluímos que as técnicas de análise de imagens baseadas em superfície cortical se mostram promissoras no estudo de doenças cerebrais que, de maneiras distintas, afetam a espessura cortical. Descritores: 1.Imagem por ressonância magnética 2.Processamento automatizado de dados 3.Doença de Alzheimer 4.Malformações do desenvolvimento corticalThe techniques of brain morphometry based on magnetic resonance images since the beginning of the twenty-first century has been an important tool for studying neurological diseases. One of the benefits of this technique is to provide measures of parameters that are difficult to estimate manually and subject to operator bias. This study aimed to describe the changes in the cortex in two diseases, a malformation of cortical development and a neurodegenerative one, using surface based morphometry techniques. From a group of patients with malformation of cortical development were analyzed 3 with polymicrogyria (PMG), compared to a group of 14 healthy age matched subjects. The images from a T1 weighted volume were analyzed using a specific algorithm, implemented in the software FreeSurfer (Fischl et al., Harvard University - United States). We analyzed 14 patients with degenerative changes (Alzheimers disease - AD) with recent onset, advanced age and high level of education compared to 20 healthy age matched elderly. The images of this study were also obtained from a T1 weighted volume and were analyzed with the same software package. This analyzed data was used to separate the two groups through a multivariate classifier, implemented by the author. The analysis of each individual with PMG compared to the control group showed a statistically significant increase in cortical thickness in the areas with polymicrogyria and also a statistically significant reduction of cortical thickness in some areas without polymicrogyria. In the study group of AD patients the result was a cortical thinning statistically significant in hippocampal, entorhinal, limbic and superior temporal cortex. Moreover, the volume of subcortical structures has provided a classification power of 84.6% discriminating AD patients from healthy controls. We conclude that the surface based cortical analysis have shown a good potential in the study of brain diseases that affect, in different ways, the cortical thickness.
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Heideklang, René. "Data Fusion for Multi-Sensor Nondestructive Detection of Surface Cracks in Ferromagnetic Materials." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19586.
Full textAbstract:
Ermüdungsrissbildung ist ein gefährliches und kostenintensives Phänomen, welches frühzeitig erkannt werden muss. Weil kleine Fehlstellen jedoch hohe Testempfindlichkeit erfordern, wird die Prüfzuverlässigkeit durch Falschanzeigen vermindert. Diese Arbeit macht sich deshalb die Diversität unterschiedlicher zerstörungsfreier Oberflächenprüfmethoden zu Nutze, um mittels Datenfusion die Zuverlässigkeit der Fehlererkennung zu erhöhen.
Der erste Beitrag dieser Arbeit in neuartigen Ansätzen zur Fusion von Prüfbildern. Diese werden durch Oberflächenabtastung mittels Wirbelstromprüfung, thermischer Prüfung und magnetischer Streuflussprüfung gewonnen. Die Ergebnisse zeigen, dass schon einfache algebraische Fusionsregeln gute Ergebnisse liefern, sofern die Daten adäquat vorverarbeitet wurden. So übertrifft Datenfusion den besten Einzelsensor in der pixelbasierten Falscherkennungsrate um den Faktor sechs bei einer Nutentiefe von 10 μm.
Weiterhin wird die Fusion im Bildtransformationsbereich untersucht. Jedoch werden die theoretischen Vorteile solcher richtungsempfindlichen Transformationen in der Praxis mit den vorliegenden Daten nicht erreicht. Nichtsdestotrotz wird der Vorteil der Fusion gegenüber Einzelsensorprüfung auch hier bestätigt.
Darüber hinaus liefert diese Arbeit neuartige Techniken zur Fusion auch auf höheren Ebenen der Signalabstraktion. Ein Ansatz, der auf Kerndichtefunktionen beruht, wird eingeführt, um örtlich verteilte Detektionshypothesen zu integrieren. Er ermöglicht, die praktisch unvermeidbaren Registrierungsfehler explizit zu modellieren. Oberflächenunstetigkeiten von 30 μm Tiefe können zuverlässig durch Fusion gefunden werden, wogegen das beste Einzelverfahren erst Tiefen ab 40–50 μm erfolgreich auffindet. Das Experiment wird auf einem zweiten Prüfkörper bestätigt.
Am Ende der Arbeit werden Richtlinien für den Einsatz von Datenfusion gegeben, und die Notwendigkeit einer Initiative zum Teilen von Messdaten wird betont, um zukünftige Forschung zu fördern.Fatigue cracking is a dangerous and cost-intensive phenomenon that requires early detection. But at high test sensitivity, the abundance of false indications limits the reliability of conventional materials testing. This thesis exploits the diversity of physical principles that different nondestructive surface inspection methods offer, by applying data fusion techniques to increase the reliability of defect detection. The first main contribution are novel approaches for the fusion of NDT images. These surface scans are obtained from state-of-the-art inspection procedures in Eddy Current Testing, Thermal Testing and Magnetic Flux Leakage Testing. The implemented image fusion strategy demonstrates that simple algebraic fusion rules are sufficient for high performance, given adequate signal normalization. Data fusion reduces the rate of false positives is reduced by a factor of six over the best individual sensor at a 10 μm deep groove. Moreover, the utility of state-of-the-art image representations, like the Shearlet domain, are explored. However, the theoretical advantages of such directional transforms are not attained in practice with the given data. Nevertheless, the benefit of fusion over single-sensor inspection is confirmed a second time. Furthermore, this work proposes novel techniques for fusion at a high level of signal abstraction. A kernel-based approach is introduced to integrate spatially scattered detection hypotheses. This method explicitly deals with registration errors that are unavoidable in practice. Surface discontinuities as shallow as 30 μm are reliably found by fusion, whereas the best individual sensor requires depths of 40–50 μm for successful detection. The experiment is replicated on a similar second test specimen. Practical guidelines are given at the end of the thesis, and the need for a data sharing initiative is stressed to promote future research on this topic.
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Suo, Jin. "Investigation of blood flow patterns and hemodynamics in the human ascending aorta and major trunks of right and left coronary arteries using magnetic resonance imaging and computational fluid dynamics." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-01192005-121529/unrestricted/suo%5Fjin%5F200505%5Fphd.pdf.
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Thesis (Ph. D.)--Biomedical Engineering, Georgia Institute of Technology, 2005.Giddens, P. Don, Committee Chair ; Vito, P. Raymond, Committee Member ; Taylor, Robert, W., Committee Member ; Oshinski, John, Committee Member ; Bao, Gang, Committee Member. Includes bibliographical references.
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Miranda, Paulo Andre Vechiatto de. "Reconhecimento e delineamento sinergicos de objetos em imagens com aplicações na medicina." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/275835.
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Orientador: Alexandre Xavier FalcãoTese (doutorado) - Universidade Estadual de Campinas, Instituto de Computação
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Resumo: Segmentar uma imagem consiste em particioná-la em regiões relevantes para uma dada aplicação (e.g., objetos e fundo). A segmentação de imagem é um dos problemas mais fundamentais e desafiadores em processamento de imagem e vis¿ao computacional. O problema da segmentação representa um desafio técnico importante na computação devido 'a dificuldade da máquina em extrair informações globais sobre os objetos nas imagens (e.g., forma e textura) contando apenas com informações locais (e.g., brilho e cor) dos pixels. Segmentação de imagens envolve o reconhecimento de objetos e o delineamento. O reconhecimento é representado por tarefas cognitivas que determinam a localização aproximada de um objeto desejado em uma determinada imagem (detecção de objeto),e identificam um objeto desejado de entre uma lista de objetos candidatos (classificação de objeto). Já o delineamento consiste em definir de forma precisa a extensão espacial do objeto de interesse. No entanto, métodos de segmentação efetivos devem explorar essas tarefas de forma sinérgica. Esse tema constitui o foco central deste trabalho que apresenta soluções interativas e automáticas para segmentação. A automação é obtida mediante o uso de modelos discretos que são criados por aprendizado supervisionado. Esses modelos empregam reconhecimento e delineamento de uma maneira fortemente acoplada pelo conceito de Clouds. Estes modelos são demonstrados no âmbito da neurologia para a segmentação automática do cérebro (sem o tronco cerebral), do cerebelo, e de cada hemisfério cerebral a partir de imagens de ressonância magnética. Estas estruturas estão ligadas em várias partes, o que impõe sérios desafios para a segmentação. Os resultados indicam que estes modelos são ferramentas rápidas e precisas para eliminar as intervenções do usuário ou, pelo menos, reduzi-las para simples correções, no contexto da segmentação de imagens do cérebro.
Abstract: Segmenting an image consists of partitioning it into regions relevant for a given application (e.g., objects and background). The image segmentation is one of the most fundamental and challenging problems in image processing and computer vision. The segmentation problem represents a significant technical challenge in computer science because of the difficulty of the machine in extracting global informations about the objects in the images (e.g., shape and texture) counting only with local information (e.g., brightness and color) of the pixels. Image segmentation involves object recognition and delineation. Recognition is represented by cognitive tasks that determine the approximate location of a desired object in a given image (object detection), and identify a desired object among candidate ones (object classification), while delineation consists in defining the exact spatial extent of the object. Effective segmentation methods should exploit these tasks in a synergistic way. This topic forms the central focus of this work that presents solutions for interactive and automatic segmentation. The automation is achieved through the use of discrete models that are created by supervised learning. These models employ recognition and delineation in a tightly coupled manner by the concept of Clouds. We demonstrate their usefulness in the automatic MR-image segmentation of the brain (without the brain stem), the cerebellum, and each brain hemisphere. These structures are connected in several parts, imposing serious challenges for segmentation. The results indicate that these models are fast and accurate tools to eliminate user's intervention or, at least, reduce it to simple corrections, in the context of brain image segmentation.
Doutorado
Ciência da Computação
Doutor em Ciência da Computação
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Malkoc, Veysi. "Sequential alignment and position verification system for functional proton radiosurgery." CSUSB ScholarWorks, 2004. https://scholarworks.lib.csusb.edu/etd-project/2535.
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The purpose of this project is to improve the existing version of the Sequential Alignment and Position Verification System (SAPVS) for functional proton radiosurgery and to evaluate its performance after improvement .
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Johnson, Kevin Robert. "In Vivo Coronary Wall Shear Stress Determination Using CT, MRI, and Computational Fluid Dynamics." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14482.
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Wall shear stress (WSS) has long been identified as a factor in the development of atherosclerotic lesions. Autopsy studies have revealed a strong tendency for lesion development at arterial branch sites and along the inner walls of curvature areas that, in theory, should experience low WSS. Calculations of coronary artery WSS have typically been based upon average models of coronary artery geometry with average flow conditions and then compared to average lesion distributions. With all the averaging involved, a more detailed knowledge of the correlation between WSS and atherosclerotic lesion development might be obscured. Recent advancements in hemodynamic modeling now enable the calculation of WSS in individual subjects. An image-based approach for patient-specific calculation of in vivo WSS using computational fluid dynamics (CFD) would allow a more direct study of this correlation. New state-of-the-art technologies in multi-detector computed tomography (CT) and 3.0 Tesla magnetic resonance imaging (MRI) offer potential improvements for the measurement of coronary artery geometry and blood flow.
The overall objective of this research was to evaluate the quantitative accuracy of multi-detector CT and 3.0 Tesla MRI and incorporate those imaging modalities into a patient-specific CFD model of coronary artery WSS. Using a series of vessel motion phantoms, it has been shown that 64-detector CT can provide accurate measurements of coronary artery geometry for heart rates below 70 beats per minute. A flow phantom was used to validate the use of navigator-echo gated, phase contrast MRI at 3.0 Tesla to measure velocity of coronary blood flow. Patient-specific, time-resolved CFD models of coronary WSS were created for two subjects. Furthermore, it was determined that population-average velocity curves or steady state velocities can predict locations of high or low WSS with high degrees of accuracy compared to the use of patient-specific blood flow velocity measurements as CFD boundary conditions. This work is significant because it constitutes the first technique to non-invasively calculate in vivo coronary artery WSS using image-based, patient-specific modeling.
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CRAESMEYER, GABRIEL R. "Tratamento de efluente contendo urânio com zeólita magnética." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10578.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Navas, Portella Víctor. "Statistical modelling of avalanche observables: criticality and universality." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/670764.
Full textAbstract:
Complex systems can be understood as an entity composed by a large number of interactive elements whose emergent global behaviour cannot be derived from the local laws characterizing their constituents. The observables characterizing these systems can be observed at different scales and they often exhibit interesting properties such as lack of characteristic scales and self-similarity. In this context, power-law type functions take an important role in the description of these observables. The presence of power-law functions resembles to the situation of thermodynamic quantities close to a critical point in equilibrium critical phenomena.
Different complex systems can be grouped into the same universality class when the power-law functions characterizing their observables have the same exponents. The response of some complex systems proceeds by the so called avalanche process: a collective response of the system characterized by following an intermittent dynamics, with sudden bursts of activity separated by periods of silence. This kind of out-of-equilibrium systems can be found in different disciplines such as seismology, astrophysics, ecology, finance or epidemiology, just to mention a few of them. Avalanches are characterized by a set of observables such as the size, the duration or the energy. When avalanche observables exhibit lack of characteristic scales, their probability distributions can be statistically modelled by power-law-type distributions. Avalanche criticality occurs when avalanche observables can be characterized by this kind of distributions. In this sense, the concepts of criticality and universality, which are well defined in equilibrium phenomena, can be also extended for the probability distributions describing avalanche observables in out-of-equilibrium systems.
The main goal of this PhD thesis relies on providing robust statistical methods in order to characterize avalanche criticality and universality in empirical datasets. Due to limitations in data acquisition, empirical datasets often only cover a narrow range of observation, making it difficult to establish power-law behaviour unambiguously.
With the aim of discussing the concepts of avalanche criticality and universality, two different systems are going to be considered: earthquakes and acoustic emission events generated during compression experiments of porous materials in the laboratory (labquakes). The techniques developed in this PhD thesis are mainly focused on the distribution of earthquake and labquake sizes, which is known as the Gutenberg-Richter law. However, the methods are much more general and can be applied to any other avalanche observable.
The statistical techniques provided in this work can also be helpful for earthquake forecasting. Coulomb-stress theory has been used for years in seismology to understand how earthquakes trigger each other. Earthquake models that relate earthquake rates and Coulomb stress after a main event, such as the rate-and-state model, assume that the magnitude distribution of earthquakes is not affected by the change in the Coulomb stress. Several statistical analyses are performed to test whether the distribution of magnitudes is sensitive to the sign of the Coulomb-stress increase.
The use of advanced statistical techniques for the analysis of complex systems has been found to be necessary and very helpful in order to provide rigour to the empirical results, particularly, to those problems regarding hazard analysis.Els sistemes complexos es poden entendre com entitats compostes per un gran nombre d’elements en interacció on la seva resposta global i emergent no es pot derivar de les lleis particulars que caracteritzen cadascun dels seus constituents. Els observables que caracteritzen aquests sistemes es poden observar a diferents escales i, sovint, mostren propietats interessants tals com la manca d’escales característiques i autosimilitud. En aquest context, les funcions amb lleis de potència prenen un paper important en la descripció d’aquests observables. La presència de lleis de potència s’assimila a la situació dels fenòmens crítics en equilibri, on algunes quantitats termodinàmiques mostren un comportament funcional similar prop d’un punt crític. Diferents sistemes complexos es poden agrupar en la mateixa classe d’universalitat quan les funcions de lleis de potència que caracteritzen els seus observables tenen els mateixos exponents. Quan són conduïts externament, la resposta d’alguns sistemes complexos segueix el que s’anomonena un procès d’allaus: una resposta col·lectiva del sistema caracteritzada per seguir una dinàmica intermitent, amb sobtats increments d’activitat separats per períodes de silenci. Aquesta mena de sistemes fora de l’equilibri es poden trobar en diferents disciplines tals com la sismologia, astrofísica, ecologia, epidemologia o finances, per mencionar alguns. Les allaus estan caracteritzades per un conjunt d’observables tals com la mida, l’energia o la durada. Quan aquests observables mostren una manca d’escales característiques, les seves distribucions de probabilitat es poden modelitzar estadísticament per distribucions de lleis de potència. S’anomenen allaus crítiques aquelles en que els seus observables es poden caracteritzar per aquestes distribucions. En aquest sentit, els conceptes de criticalitat i universalitat, els quals estan ben definits per fenòmens en equilibri, es poden extendre per les distribucions de probabilitat que descriuen els observables de les allaus en sistemes fora de l’equilibri. L’objectiu principal d’aquesta tesi doctoral és proporcionar mètodes estadístics robusts per tal de caracteritzar la criticalitat i la universalitat en allaus corresponents a dades empíriques. Degut a les limitacions en l’adquisició de dades, les dades empíriques sovint cobreixen un rang petit d’observació, dificultant que es pugui establir un determinat comportament en forma de llei de potència de manera inequívoca. Amb l’objectiu de discutir els conceptes de criticalitat i universalitat en allaus, es consideraran dos sistemes diferents: els terratrèmols i els esdeveniments d’emissió acústica que es generen durant experiments de compressió de materials porosos al laboratori (labquakes). Les tècniques desenvolupades en aquesta tesi doctoral estan enfocades principalment a la distribució de la mida dels terratrèmols i labquakes, altrament coneguda com a llei de Gutenberg-Richter. No obstant, aquests mètodes són molt més generals i es poden aplicar a qualsevol observable de les allaus. Les tècniques estadístistiques proporcionades en aquest treball poden també ajudar al pronòstic de terratrèmols. Durant anys, la teoria d’esforços de Coulomb s’ha utilitzat en sismologia per tal d’entendre com els terratrèmols desencadenen l’ocurrència d’altres de nous. Els models de terratrèmols que relacionen la taxa d’ocurrència de rèpliques i l’esforç de Coulomb després d’un gran esdeveniment, assumeixen que la distribució de la mida dels terratrèmols no està afectada pel canvi en l’esforç de Coulomb. Diverses anàlisi estadístiques s’aplicaran per tal de comprovar si la distribució de magnituds és sensible al signe de l’esforç de Coulomb. S’ha provat que l’ús de tècniques estadístiques avançades en l’anàlisi de sistemes complexos és útil i necessari per tal d’aportar rigor als resultats empírics i, en particular, a problemes d’anàlisi de riscos.
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Zlotnicki, Jacques. "Sur les effets volcanomagnetiques et tectonomagnetiques." Paris 7, 1987. http://www.theses.fr/1987PA077296.
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Etude du champ magnetique terrestre sur les edifices volcaniques ou dans les regions soumises a une activite sismotectonique. Trois themes de recherche sont developpes: l'acquisition des mesures de terrain, les mesures experimentales realisees en laboratoire, et les simulations numeriques. L'etude de terrain porte sur des resultats obtenus sur les volcans de la soufriere de guadeloupe, la montagne pelee de martinique et le piton de la fournaise a la reunion
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Antonie, Luc Andre Georges. "Processing and interpretation of near-earth satellite magnetic data." Thesis, 1990. http://hdl.handle.net/10539/22164.
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A thesis submitted to the faculty of science,
University of the Witwatersrand, Johannesburg,
In fulfilment of the requirements for the
Degree of Doctor of Philosophy
Johannesburg
1990The processing of near-earth satellite magnetometer data towards extracting an improved lithosphere anomaly map is addressed. The two aspects of the data reduction route where data quality has been compromised most by contemporary methods is researched, namely;[Abbreviated Abstract. Open document to view full version]
GR2017
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Gearheart, Jason Aaron. "Analysis of NMR spectra using digital signal processing techniques." 2006. http://etd.louisville.edu/data/UofL0227t2006.pdf.
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Thesis (M.Eng.)--University of Louisville, 2006.Title and description from thesis home page (viewed Jan. 30, 2007). Department of Computer Engineering and Computer Science. "December 2006." Includes bibliographical references (p. 32-33).