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Photoacoustic computed tomography (PACT) is an emerging computed imaging modality that exploits optical contrast and ultrasonic detection principles to form images of the absorbed optical energy density within tissue. The PACT reconstruction problem corresponds to a time-domain inverse source problem, where the initial pressure distribution is recovered from the wavefield recorded on a measurement...
In this talk, we will propose a new optimization scheme for solving electromagnetic inverse scattering problems. In the inverse scattering problemthe physical properties of hidden targets, i.e., the permittivity and/or permeability can be retrieve from the measured scattering data excited by several incidences. In [1], by the MR-FFT-TSOM, the almost perfect ‘Austria’ profile, with permittivity εr...
Cancer is one of the leading cause of death worldwide, and an early detected cancer is likely to get better treatment. Widely used modalities for scanning the presence of cancer such as Computed Tomography and Magnetic Resonance Imaging still have problems related to the cost, size and equipment complexity. Microwave imaging is considered as an alternative modality due to its low health risk, low...
We report parallel solutions of inverse multiple scattering problems with the Born iterative method (BIM) and the distorted Born iterative method (DBIM). The large computational costs of the Born solvers are reduced using the multilevel fast multipole algorithm (MLFMA). Furthermore, the solutions are obtained on supercomputing environments via parallelization of the Born solvers. This is achieved...
In general imaging process, electromagnetic waves scattered on an object can regard as an inverse scattering problem, and imaging in different method vary from imaging model. We introduce a novel microwave imaging system based on compressed sensing (CS), allowing image reconstruction with fewer samples than conventional required. It is found that a sparse scene could be rebuilt under acceptable non-correlated...
Time reversal imaging methods have received considerable attention since they yield accurate location estimate of point scatterers. Up to now, most time reversal methods have focused on detection and localization of point-like or small targets [1, 2] and not dealt with estimation of electrical parameter profile of scatterers. We have proposed a gradient based time-reversal imaging technique which...
Imaging techniques exploiting sparseness-regularized formulations emerged in the last few years as powerful and effective retrieval methods in several heterogeneous scenarios [1] including structural monitoring, non-destructive testing and evaluation, ground penetrating radar imaging, and biomedical diagnosis [2–8]. The success of the this class of algorithms, which are often collectively indicated...
Recent years has witnessed a growing interest in the research for featured-enhanced high-resolution microwave imaging field. The existing methods for radar image process are classified into image processing and target classification. Though these methods can effectively improve the imaging quality, the fact we have to meet is that lots of useful image information would be discarded in the procedure...
Kaczmarz algorithm (KA), also known as algebraic reconstruction technique (ART) in medical imaging area, is a commonly used iterative method for solving large-scale linear system of equations. It has found wide applications in many fields such as medical imaging, electromagnetic inverse scattering and geophysics. Various improved KAs have been developed to promote the efficiency of the algorithm,...
When improved ultra-wide band characteristic basis function method (IUCBFM) is used to calculate wideband radar cross section (RCS) of objects, the reduced matrix at each frequency point need to be reconstructed, which is very time-consuming. To solve this problem, an effective numerical method to fast calculate wideband RCS of objects by combining IUCBFM and asymptotic waveform evaluation (AWE) technique...
Usage of electrical impedance tomography and electrical resistance tomography will be in the article. The electrical impedance tomography is a widely investigated problem with many applications in physical and biological sciences. Medical imaging can be used primarily for the detection of pulmonary emboli, non-invasive monitoring of heart function and blood flow, and for breast cancer detection. Electrical...
In this paper the implementation of the Sparse or Compressed Sensing (CS) technique to subsurface holography allowing data acquisition on a sparse grid is considered, which raises the scanning speed, reduces the amount of stored and transmitted data. To test various aspects of applying CS technique, a custom-built experimental setup acquiring data at several programmable sampling intervals was used...
Nonlinear inversion algorithms of electromagnetic data have been widely used in many areas to reconstruct the electrical properties of unknown domains. However, their applications are still restricted by the computational cost when processing large datasets. Many efforts have been made on developing fast nonlinear inversion algorithms, but few of them was focused on the characteristics of the hardware...
Downward looking sparse linear array three-dimensional synthetic aperture radar (DLSLA 3-D SAR) can obtain the 3-D image of the true scene, and compressive sensing (CS) provide the solution for cross-track super-resolution reconstruction. This paper concerns the issue of optimizing the measurement matrix, which affects the reconstruction performance. Two mutual coherence based criteria are proposed...
For sparse Radar signals, sparse imaging method is subversion of the traditional imaging method, which breaks through the limitations existing in traditional imaging method. In order to improve the imaging quality of Radar signals, we don't only realize the sparse radar imaging algorithm, but also propose a new method for choosing regularization parameter in 2D radar imaging. The imaging result verifies...
The comparison of the modern microwave screening systems is given in this paper in the aspect of employing mono-static or multi-static antenna configuration, with their numerical models described and applied in the presented numerical experiments. The phenomenological model of scattering from human body and foreign objects is used to obtain the radar signal, which is processed according to the given...
Holographic multiplexing is capable of recording multiple images in the same area to increase the information capacity and make the optimum use of the space-bandwidth product. Unlike volume holographic recording systems with Bragg-based selectivity, holographic multiplexing based on metasurfaces is a quite distinct field. Here, by combining the synthetic spectrum method with a geometric phase metasurface...
The perturbation method for open boundary problems based on the equivalence theorem has been proposed. Most of the open boundary techniques in electromagnetic analysis are approximate, whereas more accurate techniques require large computational resources. In order to improve the accuracy of the open boundary solution, the equivalence theorem has been employed as a perturbation correction to the electromagnetic...
This paper presents a position correcting method concerning the existing problem in the forward approach to establish component-level parametric scattering center models for known complex radar targets. The forward approach decomposes the target-model of radar into some parts and then extracts the scattering centers and their parameters through radar simulation. In the actual utilization of the forward...
Millimeter wave Near-field 3-D imaging has great importance on security applications for its penetrating characteristics and the 3-D information of the target. To obtain accurate and high resolution images, we propose a direct 3-D integral method to reconstruct the 3-D images. The algorithm directly processes the scattered data without any interpolation or approximation, making it more accurate than...
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