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Number of results: 6
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Abstract

The computing performance optimization of the Short-Lag Spatial Coherence (SLSC) method applied to ultrasound data processing is presented. The method is based on the theory that signals from adjacent receivers are correlated, drawing on a simplified conclusion of the van Cittert-Zernike theorem. It has been proven that it can be successfully used in ultrasound data reconstruction with despeckling. Former works have shown that the SLSC method in its original form has two main drawbacks: time-consuming processing and low contrast in the area near the transceivers. In this study, we introduce a method that allows to overcome both of these drawbacks.

The presented approach removes the dependency on distance (the “lag” parameter value) between signals used to calculate correlations. The approach has been tested by comparing results obtained with the original SLSC algorithm on data acquired from tissue phantoms.

The modified method proposed here leads to constant complexity, thus execution time is independent of the lag parameter value, instead of the linear complexity. The presented approach increases computation speed over 10 times in comparison to the base SLSC algorithm for a typical lag parameter value. The approach also improves the output image quality in shallow areas and does not decrease quality in deeper areas.

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Authors and Affiliations

Jakub Domaradzki
Marcin Lewandowski
Norbert Żołek
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Abstract

The objective of this paper is an experimental study of the most crucial parameters of the received acoustic signals (e.g. signal-to-noise ratio (SNR), side-lobes level (SLL), axial resolution) obtained as a result of simultaneous emission of mutually orthogonal Golay complementary sequences (MOGCS) to demonstrate their feasibility of being used in ultrasound diagnostics. Application of the MOGCS in ultrasound measurements allows the image reconstruction time to be shortened without decreasing the resulting quality of reconstructed images in comparison with regular complementary Golay coded sequences (CGCS). In this paper two sets of 16-bits long MOGCS were implemented in the Verasonics Vantage TM (Verasonics Inc., Kirkland, WA, USA) scanner. Ultrasound data were generated using a perfect reflector, a custom-made nylon wire phantom and tissue mimicking phantom. Parameters of the detected MOGCS echoes like SNR, SLL and axial resolution were determined and compared to that of the standard CGCS and the short two-sine cycles pulse. It was evidenced that applying MOGCS did not compromise the parameters of the separated and compressed echoes in comparison to the other types of transmitted signal – the CGCS and the short pulse. Concretely, both the MOGCS and CGCS yield similar SNR increase in comparison to the short pulse. Almost similar values of the axial resolution estimated at the full width at the half maximum level for all types of the transmitted signals were also obtained. At the same time, using the MOGCS the data acquisition speed can be increased twice in comparison with the CGCS signal.
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Authors and Affiliations

Ihor Trots
1
Norbert Żołek
1
Yurij Tasinkevych
1
Janusz Wójcik
1

  1. Ultrasound Department, Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw, Poland
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Abstract

This paper presents that the effect of single aperture size of metallic enclosure on electrical shielding effectiveness (ESE) at 0 – 1 GHz frequency range has been investigated by using both Robinson’s analytical formulation and artificial neural networks (ANN) methods that are multilayer perceptron (MLP) networks and a radial basis function neural network (RBFNN). All results including measurement have been compared each other in terms of aperture geometry of metallic enclosure. The geometry of single aperture varies from square to rectangular shape while the open area of aperture is fixed. It has been observed that network structure of MLP 3-40-1 in modeling with ANN modeled with fewer neurons in the sense of overlapping of faults and data and modeled accordingly. In contrast, the RBFNN 3-150-1 is the other detection that the network structure is modeled with more neurons and more. It can be seen from the same network-structured MLP and RBFNN that the MLP modeled better. In this paper, the impact of dimension of rectangular aperture on shielding performance by using RBFNN and MLP network model with ANN has been studied, as a novelty.

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Authors and Affiliations

Ibrahim Bahadir Basyigit
Habib Dogan
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Abstract

This article applies radar interferometry technologies implemented in the ENVI SARscape and SNAP software environment provided by the processing of data from the Sentinel-1 satellite. The study was carried out based on six radar images of Sentinel-1A and Sentinel -1B taken from September 2017 until February 2018 with an interval of one month and on the radar-module of the already mentioned SNAP software. The main input data for solving the considered problem are radar images received from the satellite Sentinel-1B on the territory of Stebnyk-Truskavets for six months with an interval of one month. Monitoring of the Earth’s surface using radar data of the Sentinel-1A with a synthesized aperture is implemented with the application of interferometric methods of Persistent Scatterers and Small baselines interferometry for estimating small displacements of the Earth’s surface and structures. The obtained quantitative and qualitative indicators of monitoring do not answer the processes that take place and lead to vertical displacements the six months but do provide an opportunity to assess the extent and trends of their development. The specification in each case can be accomplished by ground methods, which greatly simplify the search for sites with critical parameters of vertical displacements which can have negative consequences and lead to an emergency.

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Authors and Affiliations

Ihor Trevoho
ORCID: ORCID
Borys Chetverikov
ORCID: ORCID
Lubov Babiy
ORCID: ORCID
Mariia Malanchuk
ORCID: ORCID
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Abstract

For high speed downlinking of payload data from small satellites, a new 4×4 aperture coupled microstrip patch array antenna has been presented. The antenna is designed for the Ku band and a peak gain of 18.0 dBi is achieved within the impedance bandwidth from 11.75 GHz to 12.75 GHz. Wide bandwidth is achieved as the patch elements are excited through E-shaped slots having asymmetric side lengths and widths. Each square patch element of the array with truncated corners and appropriately placed slots generates right hand circularly polarized (RHCP) radiation with very high crosspolarization discrimination. A corporate feed network consisting of T-junctions and quarter-wave impedance transformers is developed to feed the array elements from a single coaxial port of 50 Ω. To improve the radiation from the patches and waveguiding in the feed network, two types of Rogers substrates with different dielectric constant and thickness are considered. Our proposed microstrip patch array antenna of size 7.8 cm × 6.4 cm × 0.3 cm can perform efficiently with a downlink data rate as high as 4.6 Gbps for small satellites.
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Authors and Affiliations

Kajol Chandra Paul
1
Anis Ahmed
2

  1. Dept. of Electrical and Electronic Engineering, Jatiya Kabi Kazi Nazrul Islam University, Mymensingh, Bangladesh
  2. Dept. of Electrical and Electronic Engineering, University of Dhaka, Dhaka, Bangladesh

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