scholarly journals Resolution Enhanced of GRBR Observation-Based Ionospheric Tomography in Indonesia

2019 ◽  
Vol 2 ◽  
pp. 259-265
Author(s):  
Timbul Manik ◽  
Adi Purwono ◽  
Musthofa Lathif ◽  
Mario Batubara ◽  
Mamoru Yamamoto
Keyword(s):  
Vertical Direction ◽  
Grid Resolution ◽  
Reconstruction Technique ◽  
Algebraic Reconstruction Technique ◽  
Computation Result ◽  
Ionospheric Tomography ◽  
Best Value ◽  
Tomography Reconstruction ◽  
Radio Beacon

An ionospheric tomography reconstruction using Algebraic Reconstruction Technique (ART) method has been successfully carried out recently. Data utilized on this work was a campaign-based Gnu-Radio Beacon Receiver (GRBR) observation in West Java during 8-10 November 2016 and 25-29 September 2017 data. Grid resolution of the tomography previously had been increased in the in the latitudinal (0.5o horizontal direction) and altitude (~25 km in vertical direction) scales. Although the quality of the tomography has also met a compatibility level through the correlation analysis (e.g. 85% of correlation coefficient), the computation result should be improved in order to get the best value of bias frequency (i.e. < 1 MHz). Through this opportunity, the result of the tomography within the grid resolution of 0.5o and ~25 km for the latitude and altitude respectively is presented.

A modified discrete tomography for improving the reconstruction of unknown multi-gray-level material in the `missing wedge' situation

2018 ◽  
Vol 25 (6) ◽  
pp. 1847-1859 ◽  
Author(s):  
Jianhong Liu ◽  
Zhiting Liang ◽  
Yong Guan ◽  
Wenbin Wei ◽  
Haobo Bai ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Iteration Process ◽  
Reconstruction Technique ◽  
Morphological Operations ◽  
Algebraic Reconstruction Technique ◽  
Discrete Tomography ◽  
Boundary Extraction ◽  
X Ray ◽  
Dimensional Reconstruction

Full angular rotational projections cannot always be acquired in tomographic reconstructions because of the limited space in the experimental setup, leading to the `missing wedge' situation. In this paper, a recovering `missing wedge' discrete algebraic reconstruction technique algorithm (rmwDART) has been proposed to solve the `missing wedge' problem and improve the quality of the three-dimensional reconstruction without prior knowledge of the material component's number or the material's values. By using oversegmentation, boundary extraction and mathematical morphological operations, `missing wedge' artifact areas can be located. Then, in the iteration process, by updating the located areas and regions, high-quality reconstructions can be obtained from the simulations, and the reconstructed images based on the rmwDART algorithm can be obtained from soft X-ray nano-computed tomography experiments. The results showed that there is the potential for discrete tomography.

scholarly journals SART-Type Image Reconstruction from a Limited Number of Projections with the Sparsity Constraint

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Hengyong Yu ◽  
Ge Wang
Keyword(s):  
Image Reconstruction ◽  
Haar Wavelet ◽  
Reconstruction Technique ◽  
Algebraic Reconstruction Technique ◽  
Haar Wavelet Transform ◽  
Linear Inverse Problems ◽  
Sparsity Constraints ◽  
Sparsity Constraint ◽  
Simultaneous Algebraic Reconstruction Technique

Based on the recent mathematical findings on solving the linear inverse problems with sparsity constraints by Daubechiesx et al., here we adapt a simultaneous algebraic reconstruction technique (SART) for image reconstruction from a limited number of projections subject to a sparsity constraint in terms of an invertible compression transform. The algorithm is implemented with an exemplary Haar wavelet transform and tested with a modified Shepp-Logan phantom. Our preliminary results demonstrate that the sparsity constraint helps effectively improve the quality of reconstructed images and reduce the number of necessary projections.

scholarly journals Variable Weighted Ordered Subset Image Reconstruction Algorithm

2006 ◽  
Vol 2006 ◽  
pp. 1-7 ◽  
Author(s):  
Jinxiao Pan ◽  
Tie Zhou ◽  
Yan Han ◽  
Ming Jiang
Keyword(s):  
Numerical Simulation ◽  
Iterative Reconstruction ◽  
Reconstruction Algorithm ◽  
Reconstruction Technique ◽  
Algebraic Reconstruction Technique ◽  
Reconstruction Algorithms ◽  
Ct Data ◽  
Simultaneous Algebraic Reconstruction Technique ◽  
Algebraic Reconstruction

We propose two variable weighted iterative reconstruction algorithms (VW-ART and VW-OS-SART) to improve the algebraic reconstruction technique (ART) and simultaneous algebraic reconstruction technique (SART) and establish their convergence. In the two algorithms, the weighting varies with the geometrical direction of the ray. Experimental results with both numerical simulation and real CT data demonstrate that the VW-ART has a significant improvement in the quality of reconstructed images over ART and OS-SART. Moreover, both VW-ART and VW-OS-SART are more promising in convergence speed than the ART and SART, respectively.

A modified discrete algebraic reconstruction technique for multiple grey image reconstruction for limited angle range tomography

2016 ◽  
Vol 23 (2) ◽  
pp. 606-616 ◽  
Author(s):  
Zhiting Liang ◽  
Yong Guan ◽  
Gang Liu ◽  
Xiangyu Chen ◽  
Fahu Li ◽  
...  
Keyword(s):  
Prior Knowledge ◽  
Homogeneous Material ◽  
Reconstruction Technique ◽  
Algebraic Reconstruction Technique ◽  
Simulation Experiments ◽  
Linear Projection ◽  
Projection Equations ◽  
Limited Angle ◽  
Algebraic Reconstruction

The `missing wedge', which is due to a restricted rotation range, is a major challenge for quantitative analysis of an object using tomography. With prior knowledge of the grey levels, the discrete algebraic reconstruction technique (DART) is able to reconstruct objects accurately with projections in a limited angle range. However, the quality of the reconstructions declines as the number of grey levels increases. In this paper, a modified DART (MDART) was proposed, in which each independent region of homogeneous material was chosen as a research object, instead of the grey values. The grey values of each discrete region were estimated according to the solution of the linear projection equations. The iterative process of boundary pixels updating and correcting the grey values of each region was executed alternately. Simulation experiments of binary phantoms as well as multiple grey phantoms show that MDART is capable of achieving high-quality reconstructions with projections in a limited angle range. The interesting advancement of MDART is that neither prior knowledge of the grey values nor the number of grey levels is necessary.

scholarly journals Three-dimensional ionospheric tomography by an improved algebraic reconstruction technique

GPS Solutions ◽  
2007 ◽  
Vol 11 (4) ◽  
pp. 251-258 ◽  
Author(s):  
Debao Wen ◽  
Yunbin Yuan ◽  
Jikun Ou ◽  
Xingliang Huo ◽  
Kefei Zhang
Keyword(s):  
Three Dimensional ◽  
Reconstruction Technique ◽  
Algebraic Reconstruction Technique ◽  
Ionospheric Tomography ◽  
Algebraic Reconstruction

scholarly journals GPS-based ionospheric tomography with a constrained adaptive simultaneous algebraic reconstruction technique

2015 ◽  
Vol 124 (2) ◽  
pp. 283-289 ◽  
Author(s):  
WEN DEBAO ◽  
ZHANG XIAO ◽  
TONG YANGJIN ◽  
ZHANG GUANGSHENG ◽  
ZHANG MIN ◽  
...  
Keyword(s):  
Reconstruction Technique ◽  
Algebraic Reconstruction Technique ◽  
Ionospheric Tomography ◽  
Simultaneous Algebraic Reconstruction Technique ◽  
Algebraic Reconstruction
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