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Article
Publication date: 19 June 2017

Qi Wang, Pengcheng Zhang, Jianming Wang, Qingliang Chen, Zhijie Lian, Xiuyan Li, Yukuan Sun, Xiaojie Duan, Ziqiang Cui, Benyuan Sun and Huaxiang Wang

Electrical impedance tomography (EIT) is a technique for reconstructing the conductivity distribution by injecting currents at the boundary of a subject and measuring the…

Abstract

Purpose

Electrical impedance tomography (EIT) is a technique for reconstructing the conductivity distribution by injecting currents at the boundary of a subject and measuring the resulting changes in voltage. Image reconstruction for EIT is a nonlinear problem. A generalized inverse operator is usually ill-posed and ill-conditioned. Therefore, the solutions for EIT are not unique and highly sensitive to the measurement noise.

Design/methodology/approach

This paper develops a novel image reconstruction algorithm for EIT based on patch-based sparse representation. The sparsifying dictionary optimization and image reconstruction are performed alternately. Two patch-based sparsity, namely, square-patch sparsity and column-patch sparsity, are discussed and compared with the global sparsity.

Findings

Both simulation and experimental results indicate that the patch based sparsity method can improve the quality of image reconstruction and tolerate a relatively high level of noise in the measured voltages.

Originality/value

EIT image is reconstructed based on patch-based sparse representation. Square-patch sparsity and column-patch sparsity are proposed and compared. Sparse dictionary optimization and image reconstruction are performed alternately. The new method tolerates a relatively high level of noise in measured voltages.

Details

Sensor Review, vol. 37 no. 3
Type: Research Article
ISSN: 0260-2288

Keywords

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Article
Publication date: 19 September 2016

Ziqiang Cui, Qi Wang, Qian Xue, Wenru Fan, Lingling Zhang, Zhang Cao, Benyuan Sun, Huaxiang Wang and Wuqiang Yang

Electrical capacitance tomography (ECT) and electrical resistance tomography (ERT) are promising techniques for multiphase flow measurement due to their high speed, low…

Abstract

Purpose

Electrical capacitance tomography (ECT) and electrical resistance tomography (ERT) are promising techniques for multiphase flow measurement due to their high speed, low cost, non-invasive and visualization features. There are two major difficulties in image reconstruction for ECT and ERT: the “soft-field”effect, and the ill-posedness of the inverse problem, which includes two problems: under-determined problem and the solution is not stable, i.e. is very sensitive to measurement errors and noise. This paper aims to summarize and evaluate various reconstruction algorithms which have been studied and developed in the word for many years and to provide reference for further research and application.

Design/methodology/approach

In the past 10 years, various image reconstruction algorithms have been developed to deal with these problems, including in the field of industrial multi-phase flow measurement and biological medical diagnosis.

Findings

This paper reviews existing image reconstruction algorithms and the new algorithms proposed by the authors for electrical capacitance tomography and electrical resistance tomography in multi-phase flow measurement and biological medical diagnosis.

Originality/value

The authors systematically summarize and evaluate various reconstruction algorithms which have been studied and developed in the word for many years and to provide valuable reference for practical applications.

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Article
Publication date: 14 August 2021

Peng Fan and Y.C. Kuang

The rotor in screw motor is driven to rotate by highly pressure difference of drilling fluid (DF), while rotor drives drill bit to break rocks. DF works in the volume…

Abstract

Purpose

The rotor in screw motor is driven to rotate by highly pressure difference of drilling fluid (DF), while rotor drives drill bit to break rocks. DF works in the volume cavity (VC) which exists between the stator and rotor (SAR), these process realizes the conversion from hydraulic energy to mechanical energy finally. In order to assure seal performance and output power reliability of VC in common hypocycloid screw motor (CHSM), it’s essential to survey SAR end-face profile.

Design/methodology/approach

In this article, based on the internal and external cycloid method given for SAR end-face of φ172 7/8-head LZ type CHSM, the interference among SAR is established based on the meshing model through theoretical equilibrium method (TEM). Last, the reasonable design value of SAR interference in TEM is verified with the hydraulic parameters test results.

Findings

The profile optimization that top-root part of rotor end-face profiles is replaced by elliptical-circular arcs (ECA) makes the transition area of tooth-top and tooth-root connect smoother than before. The reasonable interference of SAR in TEM is almost 0.16mm~0.22mm to ensure better sealing performance. Through the hydraulic test, the interference positive fluctuation or the number of SAR head reduces increase (starting-pressure-drop) SPD while negative fluctuations by contraries. Meanwhile, DF penetration also decreases the revolution speed with the SAR interference decreases. The less SAR head revolution speed is always below the more with the constant driving power and DF hydraulic drop. Ultimately, decreasing in overall-efficiency occurs for larger fluctuation of interference or or less interference among SAR.

Originality/value

The line type optimization and analysis in TEM for CHSM improves the motor seal and output performance, also has important application values simultaneously.

Details

Industrial Lubrication and Tribology, vol. 73 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

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