Tesis sobre el tema "Inverse imaging"
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Lecharlier, Loïc. "Blind inverse imaging with positivity constraints". Doctoral thesis, Universite Libre de Bruxelles, 2014. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209240.
Texto completoDoctorat en Sciences
info:eu-repo/semantics/nonPublished
Javanmard, Mehdi. "Inverse problem approach to ultrasound medical imaging". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0001/NQ31933.pdf.
Texto completoLeung, Wun Ying Valerie. "Inverse problems in astronomical and general imaging". Thesis, University of Canterbury. Electrical and Computer Engineering, 2002. http://hdl.handle.net/10092/7513.
Texto completoPapadopoulos, Timoleon. "Inverse filtering for virtual acoustic imaging systems". Thesis, University of Southampton, 2006. https://eprints.soton.ac.uk/157421/.
Texto completoGregson, James. "Applications of inverse problems in fluids and imaging". Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54081.
Texto completoScience, Faculty of
Computer Science, Department of
Graduate
Li, Xiaobei. "Instrumentation and inverse problem solving for impedance imaging /". Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/5973.
Texto completoOster, Howard Steven. "Electrocardiographic imaging: New applications and new inverse methodology". Case Western Reserve University School of Graduate Studies / OhioLINK, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=case1058380620.
Texto completoSzasz, Teodora. "Advanced beamforming techniques in ultrasound imaging and the associated inverse problems". Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30221/document.
Texto completoUltrasound (US) allows non-invasive and ultra-high frame rate imaging procedures at reduced costs. Cardiac, abdominal, fetal, and breast imaging are some of the applications where it is extensively used as diagnostic tool. In a classical US scanning process, short acoustic pulses are transmitted through the region-of-interest of the human body. The backscattered echo signals are then beamformed for creating radiofrequency(RF) lines. Beamforming (BF) plays a key role in US image formation, influencing the resolution and the contrast of final image. The objective of this thesis is to model BF as an inverse problem, relating the raw channel data to the signals to be recovered. The proposed BF framework improves the contrast and the spatial resolution of the US images, compared with the existing BF methods. To begin with, we investigated the existing BF methods in medical US imaging. We briefly review the most common BF techniques, starting with the standard delay-and-sum BF method and emerging to the most known adaptive BF techniques, such as minimum variance BF. Afterwards, we investigated the use of sparse priors in creating original two-dimensional beamforming methods for ultrasound imaging. The proposed approaches detect the strong reflectors from the scanned medium based on the well-known Bayesian Information Criteria used in statistical modeling. Furthermore, we propose a new way of addressing the BF in US imaging, by formulating it as a linear inverse problem relating the reflected echoes to the signal to be recovered. Our approach offers flexibility in the choice of statistical assumptions on the signal to be beamformed and it is robust to a reduced number of pulse emissions. At the end of this research, we investigated the use of the non-Gaussianity properties of the RF signals in the BF process, by assuming alpha-stable statistics of US images
Zhu, Sha. "A Bayesian Approach for Inverse Problems in Synthetic Aperture Radar Imaging". Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00844748.
Texto completoRückert, Nadja. "Studies on two specific inverse problems from imaging and finance". Doctoral thesis, Universitätsbibliothek Chemnitz, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-91587.
Texto completoRam, Sundaresh y Sundaresh Ram. "Sparse Representations and Nonlinear Image Processing for Inverse Imaging Solutions". Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/626164.
Texto completoSom, Subhojit. "Topics in Sparse Inverse Problems and Electron Paramagnetic Resonance Imaging". The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1282135281.
Texto completoZhang, Wenlong. "Forward and Inverse Problems Under Uncertainty". Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEE024/document.
Texto completoThis thesis contains two different subjects. In first part, two cases are considered. One is the thin plate spline smoother model and the other one is the elliptic boundary equations with uncertain boundary data. In this part, stochastic convergences of the finite element methods are proved for each problem.In second part, we provide a mathematical analysis of the linearized inverse problem in multifrequency electrical impedance tomography. We present a mathematical and numerical framework for a procedure of imaging anisotropic electrical conductivity tensor using a novel technique called Diffusion Tensor Magneto-acoustography and propose an optimal control approach for reconstructing the cross-property factor relating the diffusion tensor to the anisotropic electrical conductivity tensor. We prove convergence and Lipschitz type stability of the algorithm and present numerical examples to illustrate its accuracy. The cell model for Electropermeabilization is demonstrated. We study effective parameters in a homogenization model. We demonstrate numerically the sensitivity of these effective parameters to critical microscopic parameters governing electropermeabilization
Guan, Lim Kian. "Battle damage assessment using Inverse Synthetic Aperture Radar (ISAR) /". Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Dec%5FGuan.pdf.
Texto completoThesis Advisor(s): Brett H. Borden, Donald L. Walters. Includes bibliographical references (p. 97-98). Also available online.
Travis, Clive Hathaway. "The inverse problem and applications to optical and eddy current imaging". Thesis, University of Surrey, 1989. http://epubs.surrey.ac.uk/804869/.
Texto completoZamanian, Sam Ahmad. "Hierarchical Bayesian approaches to seismic imaging and other geophysical inverse problems". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92970.
Texto completoThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 189-196).
In many geophysical inverse problems, smoothness assumptions on the underlying geologic model are utilized to mitigate the effects of poor data coverage and observational noise and to improve the quality of the inferred model parameters. In the context of Bayesian inference, these smoothness assumptions take the form of a prior distribution on the model parameters. Conventionally, the regularization parameters defining these assumptions are fixed independently from the data or tuned in an ad hoc manner. However, it is often the case that the smoothness properties of the true earth model are not known a priori, and furthermore, these properties may vary spatially. In the seismic imaging problem, for example, where the objective is to estimate the earth's reflectivity, the reflectivity model is smooth along a particular reflector but exhibits a sharp contrast in the direction orthogonal to the reflector. In such cases, defining a prior using predefined smoothness assumptions may result in posterior estimates of the model that incorrectly smooth out these sharp contrasts. In this thesis, we explore the application of Bayesian inference to different geophysical inverse problems and seek to address issues related to smoothing by appealing to the hierarchical Bayesian framework. We capture the smoothness properties of the prior distribution on the model by defining a Markov random field (MRF) on the set of model parameters and assigning weights to the edges of the underlying graph; we refer to these parameters as the edge strengths of the MRF. We investigate two cases where the smoothing is specified a priori and introduce a method for estimating the edge strengths of the MRF. In the first part of this thesis, we apply a Bayesian inference framework (where the edge strengths of the MRF are predetermined) to the problem of characterizing the fractured nature of a reservoir from seismic data. Our methodology combines different features of the seismic data, particularly P-wave reflection amplitudes and scattering attributes, to allow for estimation of fracture properties under a larger physical regime than would be attainable using only one of these data types. Through this application, we demonstrate the capability of our parameterization of the prior distribution with edge strengths to both enforce smoothness in the estimates of the fracture properties and capture a priori information about geological features in the model (such as a discontinuity that may arise in the presence of a fault). We solve the inference problem via loopy belief propagation to approximate the posterior marginal distributions of the fracture properties, as well as their maximum a posteriori (MAP) and Bayes least squares estimates. In the second part of the thesis, we investigate how the parameters defining the prior distribution are connected to the model covariance and address the question of how to optimize these parameters in the context of the seismic imaging problem. We formulate the seismic imaging problem within the hierarchical Bayesian setting, where the edge strengths are treated as random variables to be inferred from the data, and provide a framework for computing the marginal MAP estimate of the edge strengths by application of the expectation-maximization (E-M) algorithm. We validate our methodology on synthetic datasets arising from 2-D models. The images we obtain after inferring the edge strengths exhibit the desired spatially-varying smoothness properties and yield sharper, more coherent reflectors. In the final part of the thesis, we shift our focus and consider the problem of timelapse seismic processing, where the objective is to detect changes in the subsurface over a period of time using repeated seismic surveys. We focus on the realistic case where the surveys are taken with differing acquisition geometries. In such situations, conventional methods for processing time-lapse data involve inverting surveys separately and subtracting the inversion models to estimate the change in model parameters; however, such methods often perform poorly as they do not correctly account for differing model uncertainty between surveys due to differences in illumination and observational noise. Applying the machinery explored in the previous chapters, we formulate the time-lapse processing problem within the hierarchical Bayesian setting and present a framework for computing the marginal MAP estimate of the time-lapse change model using the E-M algorithm. The results of our inference framework are validated on synthetic data from a 2-D time-lapse seismic imaging example, where the hierarchical Bayesian estimates significantly outperform conventional time-lapse inversion results.
by Sam Ahmad Zamanian.
Ph. D.
Bhandari, Ayush. "Inverse problems in time-of-flight imaging : theory, algorithms and applications". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/95867.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references (pages 100-108).
Time-of-Fight (ToF) cameras utilize a combination of phase and amplitude information to return real-time, three dimensional information of a scene in form of depth images. Such cameras have a number of scientific and consumer oriented applications. In this work, we formalize a mathematical framework that leads to unifying perspective on tackling inverse problems that arise in the ToF imaging context. Starting from first principles, we discuss the implications of time and frequency domain sensing of a scene. From a linear systems perspective, this amounts to an operator sampling problem where the operator depends on the physical parameters of a scene or the bio-sample being investigated. Having presented some examples of inverse problems, we discuss detailed solutions that benefit from scene based priors such sparsity and rank constraints. Our theory is corroborated by experiments performed using ToF/Kinect cameras. Applications of this work include multi-bounce light decomposition, ultrafast imaging and fluorophore lifetime estimation.
by Ayush Bhandari.
S.M.
Rangarajan, Ranjani. "Inverse Synthetic Aperture Radar Imaging for Multiple Targets Using Compressed Sensing". University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1416233543.
Texto completoDACHENA, CHIARA. "Microwave Imaging of The Neck by Means of Inverse-Scattering Techniques". Doctoral thesis, Università degli studi di Genova, 2023. https://hdl.handle.net/11567/1108293.
Texto completoWintz, Timothée. "Super-resolution in wave imaging". Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEE052/document.
Texto completoDifferent modalities in wave imaging each present limitations in terms of resolution or contrast. In this work, we present a mathematical model of the ultrafast ultrasound imaging modality and reconstruction methods which can improve contrast and resolution in ultrasonic imaging. We introduce two methods which allow to improve contrast and to locate blood vessels belowthe diffraction limit while simultaneously estimating the blood velocity. We also present a reconstruction method in electrical impedance tomography which allows reconstruction of microscopic parameters from multi-frequency measurements using the theory of homogenization
Alfowzan, Mohammed Fowzan y Mohammed Fowzan Alfowzan. "Solutions to Space-Time Inverse Problems". Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621791.
Texto completoHE, YUN. "Multiscale Signal Processing and Shape Analysis for an Inverse SAR Imaging System". NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20010704-160913.
Texto completoThe great challenge in signal processing is to devise computationally efficient and statistically optimal algorithms for estimating signals from noisy background and understanding their contents. This thesis treats the problem of multiscale signal processing and shape analysis for an Inverse Synthetic Aperture Radar (ISAR) imaging system. To address some of the limitations of conventional techniques in radar image processing, an information theoretic approach for target motion estimation is first proposed. A wavelet based multiscale method for shape enhancement is subsequently derived and followed by a regression technique for shape recognition.Building on entropy-based divergence measures which have shown promising results in many areas of engineering and image processing, we introduce in this thesis a new generalized divergence measure, namely the Jensen-Rényi divergence. Upon establishing its properties such as convexity and its upper bound etc., we apply it to image registration for ISAR focusing as well as related problems in data fusion. Attempting to extend current approaches to signal estimation in a wavelet framework, which have generally relied on the assumption of normally distributed perturbations, we propose a novel non-linear filtering technique, as a pre-processing step for the shapes obtained from an ISAR imaging system. The key idea is to project a noisy shape onto a wavelet domain and to suppress wavelet coefficients by a mask derived from curvature extrema in its scale space representation. For a piecewise smooth signal, it can be shown that filtering by this curvature mask is equivalent to preserving the signal pointwise Hölder exponents at the singular points, and to lifting its smoothness at all the remaining points. To identify a shape independently of its registration information, we propose matching two configurations by regression, using notations of general shape spaces and procrustean distances. In particular, we study the generalized matching by estimating mean shapes in two dimensions. Simulation results show that matching by way of a mean shape is more robust than matching target shapes directly.
Steenman, Daryl G. "Investigation of near-field electromagnetic source imaging using inverse Green's function integrations". Thesis, Monterey, California: Naval Postgraduate School, 1999. http://hdl.handle.net/10945/13643.
Texto completoCOLANGELI, CLAUDIO. "Clustering Inverse Beamforming and multi-domain acoustic imaging approaches for vehicles NVH". Doctoral thesis, Università Politecnica delle Marche, 2017. http://hdl.handle.net/11566/245537.
Texto completoThe interior sound perceived in vehicle cabins is a very important attribute for the user. Experimental acoustic imaging methods such as beamforming and Near-field Acoustic Holography are used in vehicles noise and vibration studies because they are capable of identifying the noise sources contributing to the overall noise perceived inside the cabin. However these techniques are often relegated to the troubleshooting phase, thus requiring additional experiments for more detailed NVH analyses. It is therefore desirable that such methods evolve towards more refined solutions capable of providing a larger and more detailed information. This thesis proposes a modular and multi-domain approach involving direct and inverse acoustic imaging techniques for providing quantitative and accurate results in frequency, time and angle domain, thus targeting three relevant types of problems in vehicles NVH: identification of exterior sources affecting interior noise, interior noise source identification, analysis of noise sources produced by rotating machines. The core finding of this thesis is represented by a novel inverse acoustic imaging method named Clustering Inverse Beamforming (CIB). The method grounds on a statistical processing based on an Equivalent Source Method formulation. In this way, an accurate localization, a reliable ranking of the identified sources in frequency domain and their separation into uncorrelated phenomena is obtained. CIB is also exploited in this work for allowing the reconstruction of the time evolution of the sources sought. Finally a methodology for decomposing the acoustic image of the sound field generated by a rotating machine as a function of the angular evolution of the machine shaft is proposed. This set of findings aims at contributing to the advent of a new paradigm of acoustic imaging applications in vehicles NVH, supporting all the stages of the vehicle design with time-saving and cost-efficient experimental techniques. The proposed innovative approaches are validated on several simulated and real experiments.
Pereira, Antonio. "Acoustic imaging in enclosed spaces". Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0066/document.
Texto completoThis thesis is concerned with the problem of noise source identification in closed spaces. The main motivation was to propose a technique which allows to locate and quantify noise sources within industrial vehicles, in a time-effective manner. In turn, the technique might be used by manufacturers for noise abatement purposes such as to provide quieter vehicles. A simplified model based on the equivalent source formulation was used to tackle the problem. It was shown that the problem is ill-conditioned, in the sense that it is very sensitive to errors in measurement data, thus regularization techniques were required. A detailed study of this issue, in particular the tuning of the so-called regularization parameter, was of importance to ensure the stability of the solution. In particular, a Bayesian regularization criterion was shown to be a very robust approach to optimally adjust the regularization parameter in an automated way. The target application concerns very large interior environments, which imposes additional difficulties, namely: (a) the positioning of the measurement array inside the enclosure; (b) a number of unknowns ("candidate" sources) much larger than the number of measurement positions. An iterative weighted formulation was then proposed to overcome the above issues by: first correct for the positioning of the array within the enclosure and second iteratively solve the problem in order to obtain a correct source quantification. In addition, the iterative approach has provided results with an enhanced spatial resolution and dynamic range. Several numerical studies have been carried out to validate the method as well as to evaluate its sensitivity to modeling errors. In particular, it was shown that the approach is affected by non-anechoic conditions, in the sense that reflections are identified as "real" sources. A post-processing technique which helps to distinguish between direct and reverberant paths has been discussed. The last part of the thesis was concerned with experimental validations and practical applications of the method. A custom spherical array consisting of a rigid sphere and 31 microphones has been built for the experimental tests. Several academic experimental validations have been carried out in semi-anechoic environments, which illustrated the advantages and limits of the method. Finally, the approach was tested in a practical application, which consisted in identifying noise sources inside a bus at driving conditions
Lim, Kian Guan. "Battle damage assessment using inverse synthetic aperture radar (ISAR)". Thesis, Monterey, California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1223.
Texto completoAn imaging radar, like ISAR, offers a combatant the capability to perform long range surveillance with high quality imagery for positive target identification. Extending this attractive feature to the battle damage assessment problem (BDA) gives the operator instant viewing of the target's behavior when it is hit. As a consequence, immediate and decisive action can be quickly taken (if required). However, the conventional Fourier processing adopted by most ISAR systems does not provide adequate time resolution to capture the target's dynamic responses during the hit. As a result, the radar image becomes distorted. To improve the time resolution, time-frequency transform (TFT) methods of ISAR imaging have been proposed. Unlike traditional Fourier-based processing, TFT's allows variable time resolution of the entire event that falls within the ISAR coherent integration period to be extracted as part of the imaging process. We have shown in this thesis that the use of linear Short Time-Frequency Transforms allows the translational response of the aircraft caused by a blast force to be clearly extracted. The TFT extracted images not only tell us how the aircraft responds to a blast effect but also provides additional information about the cause of image distortion in the traditional ISAR display.
Burvall, Anna. "Axicon imaging by scalar diffraction theory". Doctoral thesis, KTH, Microelectronics and Information Technology, IMIT, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3736.
Texto completoAxicons are optical elements that produce Bessel beams,i.e., long and narrow focal lines along the optical axis. Thenarrow focus makes them useful ine.g. alignment, harmonicgeneration, and atom trapping, and they are also used toincrease the longitudinal range of applications such astriangulation, light sectioning, and optical coherencetomography. In this thesis, axicons are designed andcharacterized for different kinds of illumination, using thestationary-phase and the communication-modes methods.
The inverse problem of axicon design for partially coherentlight is addressed. A design relation, applicable toSchell-model sources, is derived from the Fresnel diffractionintegral, simplified by the method of stationary phase. Thisapproach both clarifies the old design method for coherentlight, which was derived using energy conservation in raybundles, and extends it to the domain of partial coherence. Thedesign rule applies to light from such multimode emitters aslight-emitting diodes, excimer lasers and some laser diodes,which can be represented as Gaussian Schell-model sources.
Characterization of axicons in coherent, obliqueillumination is performed using the method of stationary phase.It is shown that in inclined illumination the focal shapechanges from the narrow Bessel distribution to a broadasteroid-shaped focus. It is proven that an axicon ofelliptical shape will compensate for this deformation. Theseresults, which are all confirmed both numerically andexperimentally, open possibilities for using axicons inscanning optical systems to increase resolution and depthrange.
Axicons are normally manufactured as refractive cones or ascircular diffractive gratings. They can also be constructedfrom ordinary spherical surfaces, using the sphericalaberration to create the long focal line. In this dissertation,a simple lens axicon consisting of a cemented doublet isdesigned, manufactured, and tested. The advantage of the lensaxicon is that it is easily manufactured.
The longitudinal resolution of the axicon varies. The methodof communication modes, earlier used for analysis ofinformation content for e.g. line or square apertures, isapplied to the axicon geometry and yields an expression for thelongitudinal resolution. The method, which is based on abi-orthogonal expansion of the Green function in the Fresneldiffraction integral, also gives the number of degrees offreedom, or the number of information channels available, forthe axicon geometry.
Keywords:axicons, diffractive optics, coherence,asymptotic methods, communication modes, information content,inverse problems
Poonawala, Amyn. "Mask design for single and double exposure optical microlithography : an inverse imaging approach /". Diss., Digital Dissertations Database. Restricted to UC campuses, 2007. http://uclibs.org/PID/11984.
Texto completoShang, Xuefeng Ph D. Massachusetts Institute of Technology. "Inverse scattering : theory and application to the imaging of the Earth's seismic discontinuities". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/87511.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references.
In this thesis we further develop concepts in inverse scattering, which enable higher resolution imaging with data from dense networks and arrays. We apply the new methods to studies of the crust beneath south Tibet and the core-mantle boundary (CMB) region beneath Central America and East Asia. First, we develop a new method, which we call passive source reverse time migration (RTM), for subsurface imaging with teleseismic array data. Multi-component array data are first propagated backward by solving the elastic wave equation. After polarization separation, a modified cross-correlation imaging condition between P and S wave constitutes is applied to obtain an inverse scattering transform. From synthetic experiments it is evident that for complex geological structures RTM is superior to traditional receiver functions analysis, such as common conversion point (CCP) stacking. Two preprocessing steps are required for RTM application on sparsely sampled teleseismic dataset: source normalization and trace interpolation. The source radiation pattern, especially the polarity of traces, is corrected by multi-channel cross-correlation technique. The unknown source signature is then estimated by principle component analysis and deconvolved from raw data by Wiener deconvolution. Curvelet interpolation with sparsity promotion is employed to interpolate irregularly and sparsely sampled traces into regular and dense grids. Synthetic and real data examples demonstrate that for typical teleseismic acquisition geometry, with 50% to 85% missing traces, the curvelet-based interpolation works remarkably well. The application on Hi-CLIMB array data in Tibetan plateau reveals clear and continuous Moho discontinuity at the depth of about 70 km, as well as fine crustal structures. Second, we use a high-frequency approximation of inverse scattering, generalized Radon transform (GRT), to probe the lowermost mantle beneath Central America and East Asia. Inverse scattering of about 130,000 ScS traces and 120,000 SKKS traces reveals multiple reflectors above the conventional D" region. This result is inconsistent with expectations from a pure thermal response of a single isochemical post-perovskite transition but can be explained with post-perovskite transitions in differentiated slab materials. Our results imply that the lowennost mantle is more complex than hitherto thought and that the presence of interfaces and compositional heterogeneity beyond the D" region.
by Xuefeng Shang.
Ph. D.
Fouda, Ahmed Elsayed. "Electromagnetic Time-Reversal Imaging and Tracking Techniques for Inverse Scattering and Wireless Communications". The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366202740.
Texto completoChang, Paul Chinling. "Physics-Based Inverse Processing and Multi-path Exploitation for Through-Wall Radar Imaging". The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306646674.
Texto completoCamargo, Erick Darío León Bueno de. "Desenvolvimento de algoritmo de imagens absolutas de tomografia por impedância elétrica para uso clínico". Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/3/3152/tde-26062014-205827/.
Texto completoElectrical Impedance Tomography is a non invasive imaging technique that can be used in clinical applications to infer living tissue impeditivity from boundary electrical measurements. Mathematically this is an non-linear ill-posed inverse problem. Usually a spatial high-pass Gaussian filter is used as a regularization method for solving the inverse problem. The main objective of this work is to propose the use of physiological and anatomical priors of tissue resistivity distribution within the thorax, also known as anatomical atlas, in conjunction with the Gaussian filter as regularization methods. The proposed methodology employs the finite element method and the Gauss-Newton algorithm in order to reconstruct three-dimensional resistivity images. The Approximation Error Theory is used to reduce discretization effects and mesh size errors. Electrical impedance tomography data and computed tomography images of physiological pulmonary changes collected in vivo in a swine were used to validate the proposed method. The images obtained are compatible with atelectasis, pneumothorax, pleural effusion and different ventilation pressures during mechanical ventilation. The results show that image reconstruction from swines with clinically significant information is feasible when both the Gaussian filter and the anatomical atlas are used as regularization methods.
Yin, Ke. "New algorithms for solving inverse source problems in imaging techniques with applications in fluorescence tomography". Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/48945.
Texto completoPetrović, Nikola. "Measurement System for Microwave Imaging Towards a Biomedical Application". Doctoral thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-24878.
Texto completoMoffitt, Michael Adam. "Functional Imaging of the Mammalian Spinal Cord". Case Western Reserve University School of Graduate Studies / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=case1081363883.
Texto completoZhang, Yu. "Inverse opal scaffolds and photoacoustic microscopy for regenerative medicine". Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50231.
Texto completoHugelier, Siewert. "Approaches to inverse problems in chemical imaging : applications in super-resolution and spectral unmixing". Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10144/document.
Texto completoBesides the chemical information, chemical imaging also offers insights in the spatial distribution of the samples. Within this thesis, we distinguish between two different types of images: spatial-temporal images (super-resolution fluorescence microscopy) and spatial-spectral images (unmixing). In early super-resolution fluorescence microscopy, a low number of fluorophores were active per image. Currently, the field evolves towards high-density imaging that requires new ways of analysis. We propose SPIDER, an image deconvolution approach with multiple penalties. These penalties directly translate the properties of the blinking emitters used in super-resolution fluorescence microscopy imaging. SPIDER allows investigating highly dynamic structural and morphological changes in biological samples with a high fluorophore density. We applied the method on live-cell imaging of a HEK-293T cell labeled with DAKAP-Dronpa and demonstrated a spatial resolution down to 55 nm and a time sampling of 0.5 s. Unmixing hyperspectral images with MCR-ALS provides spatial and spectral information of the individual contributions in the mixture. Due to loss of the pixel neighborhood during the unfolding of the hyperspectral data cube to a two-way matrix, spatial information cannot be added as a constraint during the analysis We therefore propose an alternative approach in which an additional refolding/unfolding step is performed in each iteration. This data manipulation allows global spatial features to be added to the palette of MCR-ALS constraints. From this idea, we also developed several constraints and show their application on experimental data
Henriksson, Tommy. "CONTRIBUTION TO QUANTITATIVE MICROWAVE IMAGING TECHNIQUES FOR BIOMEDICAL APPLICATIONS". Doctoral thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-5882.
Texto completoA dissertation prepared through an international convention for a joint supervision thesis with Université Paris-SUD 11, France
Microwaves in biomedicine
Hislop, Gregory Francis. "Diffraction Tomographic Imaging of Shallowly Buried Targets using Ground Penetrating Radar". Thesis, Queensland University of Technology, 2005. https://eprints.qut.edu.au/16125/1/Gregory_Hislop_Thesis.pdf.
Texto completoHislop, Gregory Francis. "Diffraction Tomographic Imaging of Shallowly Buried Targets using Ground Penetrating Radar". Queensland University of Technology, 2005. http://eprints.qut.edu.au/16125/.
Texto completoDupuy, Clément. "Reconstruction d'image pour l'acousto-optique vers une imagerie quantitative". Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLET034.
Texto completoThe optical properties of biological tissues are of significant clinical interest. Such media are highly scattering to the near-infrared light which offers the required contrast, and consequently purely optical approaches to imaging tissues at depth suffer from limited spatial resolution. Acousto-optic imaging is a multi-modal technique which overcomes this problem by combining the optical contrast of near infra-red light with the spatial resolution of ultrasound, permitting millimetre resolution at depths of several centimetres. Raw measurements made using the acousto-optic technique are corrupted by the varying optical fluence in the medium. By using inverse problem base reconstructions algorithms, it is possible to reconstruct a map of the absorption coefficient inside the medium. My PhD is conducted between Institut Langevin, in Paris, where my acousto- optics imaging setup is and the Medical Physics and Bioengineering lab in UCL, in London where I work on the reconstruction algorithms in order to achieve quantitative measurement
Wei, Hsin-Yu. "Magnetic induction tomography for medical and industrial imaging : hardware and software development". Thesis, University of Bath, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558901.
Texto completoSorensen, Thomas J. "Inverse Scattering Image Quality with Noisy Forward Data". Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2541.pdf.
Texto completoKumar, Dinesh. "Boundary-constrained inverse consistent image registration and its applications". Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/1006.
Texto completoKlepikova, Maria. "Imaging of fractured rock properties from flow and heat transport : field experiments and inverse modelling". Phd thesis, Université Rennes 1, 2013. http://tel.archives-ouvertes.fr/tel-00865302.
Texto completoWonus, Julie L. (Julie Lynn). "A circuit model for diffusive breast imaging and a numerical algorithm for its inverse problem". Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38172.
Texto completoIncludes bibliographical references (leaves 67-70).
by Julie L. Wonus.
M.Eng.
Alberti, Giovanni S. "On local constraints and regularity of PDE in electromagnetics : applications to hybrid imaging inverse problems". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:1b30b3b7-29b1-410d-ae30-bd0a87c9720b.
Texto completoBarrera, Cruz Marco Antonio. "Hybrid method algebraic/inverse radon transform for region of interest reconstruction of computed tomography images /". To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
Texto completoSingh, Satyan. "An inverse scattering approach to imaging using Marchenko equations in the presence of a free surface". Thesis, Colorado School of Mines, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10125227.
Texto completoThe Green's function is the impulse response of a system and is used to infer the properties of the system from surface measurements. In exploration seismology, imaging algorithms use estimates of the Green's functions along with surface measurements to image the subsurface, i.e. locate the Earth's interfaces and its properties, so as to identify valuable energy resources. These conventional imaging algorithms only account for singly reflected waves (primaries) in the subsurface and hence, in the subsurface image, produce false interfaces in the presence of multiply reflected waves (internal and free-surface multiples).
Recent work has shown that we can retrieve the Green's function that accounts for primaries and internal multiples. Imaging with these Green's functions reduces the artifacts caused by internal multiples compared to conventional imaging algorithms. These Green's functions require the free-surface multiples to be removed from the surface measurements before retrieval and imaging.
I modify the retrieval of the Green's function to account for free-surface reflections and therefore no longer require the free-surface multiples to be removed from the surface measurements. Thus the Green's function, in the method I propose, includes not only primaries and internal multiples but also free-surface multiples. These Green's functions are constructed from an arbitrary point in the subsurface (no physical receiver is required at this location) to the surface.
The method I use to retrieve the Green's function does not specify the approach to image the subsurface. In this thesis I also analyze different imaging strategies using the retrieved Green's functions. Imaging with these Green's functions reduces the artifacts caused by multiply reflected waves compared to standard imaging algorithms. Significantly, the Green's function that I retrieve and use for imaging require the same inputs as conventional imaging algorithms: the surface measurements and a smooth version of the subsurface velocity.
I also extend the construction of the Green's function from the subsurface to the surface to any two arbitrary points in the subsurface (no physical source or physical receiver is required at either of these locations). This Green's function is called the virtual Green's function and includes all the primaries, internal and free-surface multiples. The virtual Green's function retrieval requires the same inputs as the previously mentioned Green's functions.
Kim, Yong Yook. "Inverse Problems In Structural Damage Identification, Structural Optimization, And Optical Medical Imaging Using Artificial Neural Networks". Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/11111.
Texto completoPh. D.