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Abstract

A single acoustic vector sensor (AVS) cannot be used to find the direction-of-arrival (DOA) of two or more coherent (fully correlated) sources. We have proposed a technique for estimating DOAs (in 2D geometry) of two simultaneous coherent sources using single AVS under the assumption that acoustic sources enter in the field sequentially. The DOA estimation has been investigated with two different configurations of AVS, each consisting of three microphones in a plane. The technique has been also applied in tracking (a) an acoustic source in the presence of stationary interfering coherent source and (b) two coherent sources when the sources are changing their locations alternatively. The experimental environment has been generated using the Finite-Element Method tool viz. COMSOL to corroborate the proposed scheme.

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Authors and Affiliations

Mohd Wajid
Arun Kumar
Rajendar Bahl
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Abstract

The cyclic Electrothermal Temperature Swing Adsorption (ETSA) process in a fixed-bed column with Supersorbon K40 activated carbon (AC) was applied to remove propan-2-ol (IPA) from air. The bed was electrothermally regenerated using direct resistive heating method. The tests were performed in the range of operating parameters: IPA loading 0.18-0.26 kg/kg, voltage 19.5 V, set-point temperature 393–403 K, nitrogen flow rate 0.12 m3/h.

The analysis revealed, that raising the bed temperature resulted in an increase of desorption degree of adsorbate, reduction of regeneration time and an increase in the energy consumption. The application of insulation enabled reduction of energy consumption and regeneration time by 27% and 10%, respectively.

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Authors and Affiliations

Krzysztof Kowalski
Elżbieta Gabruś
Dorota Downarowicz
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Abstract

Anechoic tiles can significantly reduce the echo intensity of underwater vehicles, thereby increasing the difficulty of detecting such vehicles. However, the computational efficiency of conventional methods such as the finite element method (FEM) and the boundary element method (BEM) has its limitations. A fast hybrid method for modeling acoustic scattering from underwater vehicles with anechoic tiles with periodic internal cavities, is developed by combining the Kirchhoff approximation (KA) and FEM. The accuracy and rapidity of the KA method were validated by FEM. According to the actual situation, the reflection coefficients of rubber materials with two different structures under rigid backing are simulated by FEM. Using the KA method, the acoustic scattering characteristics of the underwater vehicle with anechoic tiles are obtained by inputting the reflection coefficients and the target’s geometric grid. Experiments on the monostatic target strength (TS) in the frequency range of 1 to 20 kHz and time domain echo characteristics of acoustic scattering on a benchmark scale model with anechoic tiles are conducted. The research results indicate that the TS values and echo characteristic curves of the KA solutions closely approximate the experimental results, which verifies the accuracy of the KA method in calculating the TS and echo characteristics of underwater vehicles with anechoic tiles.
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Authors and Affiliations

Fan Yang
1
Zilong Peng
2
Hao Song
3
Yuhang Tang
4
Xuhong Miao
4

  1. School of Energy and Power, Jiangsu University of Science and Technology Zhenjiang, China
  2. School of Energy and Power, Jiangsu University of Science and Technology Zhenjiang, China; PLA Unit 92578 Beijing, China
  3. Systems Engineering Research Institute Beijing, China
  4. PLA Unit 92578 Beijing, China
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Abstract

Shaping a space shouldn’t be an endless expansion of the built environemnt. New districts and new cities should be more than collections of houses, quickly produced and placed without any overarching concept. They should present streets, squares, axes, directions, as features of the area's composition. An ordered space is a sign of true modernity.

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Authors and Affiliations

Sławomir Gzell

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