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- 摘要
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- 实验方案
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[IEEE 2018 Applications of Electromagnetics in Modern Techniques and Medicine (PTZE) - Rac?awice (2018.9.9-2018.9.12)] 2018 Applications of Electromagnetics in Modern Techniques and Medicine (PTZE) - The prototype ultrasound tomography device to analyze the properties of processes
摘要： Ultrasound tomography provides the ability to analyze processes occurring inside the facility without interfering with the production, analysis and detection of obstacles, defects and various anomalies. The presented measuring system has a specially designed measuring structure (including electrodes, thanks to which it is an innovative solution in the field, particularly effective in the analysis).
关键词： Electrical Impedance Tomography,Inverse Problem,Ultrasound Tomography
更新于2025-09-09 09:28:46
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Estimation of the particle size distribution of colloids from multiangle dynamic light scattering measurements with particle swarm optimization
摘要： In this paper particle Swarm Optimization (PSO) algorithms are applied to estimate the particle size distribution (PSD) of a colloidal system from the average PSD diameters, which are measured by multi-angle dynamic light scattering. The system is considered a nonlinear inverse problem, and for this reason the estimation procedure requires a Tikhonov regularization method. The inverse problem is solved through several PSO strategies. The evaluated PSOs are tested through three simulated examples corresponding to polystyrene (PS) latexes with different PSDs, and two experimental examples obtained by simply mixing 2 PS standards. In general, the evaluation results of the PSOs are excellent; and particularly, the PSO with the Trelea’s parameter set shows a better performance than other implemented PSOs.
关键词： inverse problem,particle swarm optimization algorithm,particle size distribution,Swarm Intelligence,dynamic light scattering
更新于2025-09-09 09:28:46
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Determination of particle distributions from sedimentation measurements using a piezoelectric tuning fork sensor
摘要： In this work, a resonant quartz tuning fork sensor based measurement system is employed to study the settlement of small particles in suspension as they pass the sensing element. The resonator features varying sensitivity to fluid parameter changes along its length, with the tip being most sensitive. The spatial averaging effect is analyzed theoretically and measured by passing the sensor through a fluid–fluid interface. Subsequently, the averaging function is used for particle distribution determination from recorded resonance frequency and quality factor measurements. The associated inverse problem is of Fredholm type and is solved numerically. Based on the system specifications, detection limits, required temperature stability and expected precision are assessed and particle distribution functions of defined test dispersions are measured.
关键词： Resonant sensor,Inverse problem,Suspension,Resonance estimation,Gout
更新于2025-09-09 09:28:46
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An inverse problem for one-dimensional diffusion equation in optical tomography
摘要： In this paper, we study the one-dimensional inverse problem for the di?usion equation based optical tomography. The objective of the present work is a mathematical and numerical analysis concerning one-dimensional inverse problem. In the ?rst stage, the forward di?usion equation with boundary conditions is solved using an intermediate elliptic equation. We give the existence and the uniqueness results of the solution. An approximation of the photon density in frequency-domain is proposed using a Splines Galerkin method. In the second stage, we give theoretical results such as the stability and lipschitz-continuity of the forward solution and the Fr′echet di?erentiability of the Dirichlet-to-Neumann nonlinear map with respect to the optical parameters. The Fr′echet derivative is used to linearize the considered inverse problem. The Newton method based on the regularization technique will allow us to compute the approximate solutions of the inverse problem. Several test examples are used to verify high accuracy, e?ectiveness and good resolution properties for smooth and discontinuous optical property solutions.
关键词： Nonlinear inverse problem,Spline basis functions,Fourier transform,Di?usion transport problem,Newton method,Tikhonov regularization,Optical tomography
更新于2025-09-04 15:30:14
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Passive Detection of Small Low-Emission Sources: Two-Dimensional Numerical Case Studies
摘要： In Allmaras et al. [Inverse Prob. Imaging, Vol. 7, No. 1, p. 47 (2013)], we present the mathematical foundations for the passive detection of small low-emission radioactive sources buried in background noise using Compton gamma cameras. Here, we apply these techniques to the detection of small amounts of special nuclear material in various cargo container geometries. Simulated two-dimensional data are used. We demonstrate the feasibility of such an approach using various realistic cargo container loadings and assess the effect of angular detection errors in Compton cameras.
关键词： low signal-to-noise ratio,Passive detection,inverse problem
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Nonconvex Phaseless Near-Field Far-Field Transformation for Electrically Large Problems
摘要： A phaseless near-?eld far-?eld transformation (NFFFT) based on nonconvex optimization and suitable for electrically large problems is presented. Features include ef?cient forward and adjoint operators taken from the fast irregular antenna ?eld transformation algorithm (FIAFTA) and the memory limited L-Broyden, Fletcher, Goldfarb and Shannon (L-BFGS) method for the solution of the nonconvex optimization. Measurement results show the bene?t of specialized probes, which effectively incorporate the knowledge of partial phase differences, for phaseless near-?eld measurements. The applicability of those probes and of the proposed nonconvex transformation algorithm to electrically large problems is veri?ed by measured and simulated results.
关键词： electrically large,inverse problem,phaseless,near-?eld far-?eld transformation
更新于2025-09-04 15:30:14
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[IEEE 2018 25th IEEE International Conference on Image Processing (ICIP) - Athens, Greece (2018.10.7-2018.10.10)] 2018 25th IEEE International Conference on Image Processing (ICIP) - A Functional Framework for Ultrasound Imaging
摘要： Delay-And-Sum (DAS), the state-of-art in ultrasound imaging, is known to be sub-optimal, resulting in low resolution and contrast. Most proposed improvements involve ad-hoc re-weighting, or hit computational bottlenecks given real-time requirements. This paper takes a fresh perspective on the problem, leveraging a functional framework to obtain a regularized least-squares estimate of the tissue reflectivity function. An explicit solution is derived, which – for specific cases – can be efficiently implemented, making it suitable for real-time imaging. In our formulation, DAS appears as a back-projection without any optimal properties. We illustrate the framework through first a one-dimensional set-up, and then a two-dimensional extension with Synthetic Aperture Focusing Technique (SAFT). The one-dimensional simulations show a 77% resolution improvement with respect to DAS, which artificially limits the available bandwidth. On a standard performance-assessment phantom, simulations show that SAFT depth resolution can be improved by 71%.
关键词： Sampling Operator,Ultrasound,Array Signal Processing,Pulse Compression,Inverse Problem
更新于2025-09-04 15:30:14