R.G. Green

Bio: R.G. Green is an academic researcher from Sheffield Hallam University. The author has contributed to research in topics: Optical tomography & Process tomography. The author has an hindex of 11, co-authored 33 publications receiving 347 citations. Previous affiliations of R.G. Green include University of Sheffield.

Concentration profiles of dry powders in a gravity conveyor using an electrodynamic tomography system

Abstract: This paper presents results for a tomographic system using an array of electrodynamic sensors. Sensitivity maps are derived for the individual sensors and then used by a back-projection algorithm to calculate concentration profiles from measured sensor values. Limitations in linearity over the sensing area are reduced by applying a filter to the images. The filtered back-projection algorithm is tested both on uniformly and on artificially produced non-uniformly distributed solids' flows.

Velocity and mass flow rate profiles of dry powders in a gravity drop conveyor using an electrodynamic tomography system

Abstract: This paper describes measurements made on a gravity drop conveyor using two arrays of axially spaced electrodynamic sensors to measure axial velocities close to the wall of the conveyor and velocity profiles both of flowing sand and of plastic beads. The level of correlation obtained using pixels is investigated. The velocity profile is combined with a tomographic concentration profile to estimate the mass flow profile, which is summed over the measurement cross section to estimate the mass flow rate. A calibration of the tomographically determined mass flow rate versus the actual mass flow rate is presented.

Optical sensor configurations for process tomography

Abstract: This paper describes an investigation into the optimum design of optical fibre sensing arrays to be incorporated in an optical tomographic measurement system for on-line monitoring of particles and droplets Two approaches are considered to cover opaque and transparent materials; optical path length and optical attenuation Four flow models are investigated: single-pixel flow representing a single particle or droplet, two-pixel flow as a simple check on aliasing in the reconstructed image, half flow representing half the sensing cross section filled with material and full flow, where the whole sensing cross section is full of material Six projection geometries of the fibre sensors are considered For tomographic imaging, the forward problem, which assumes particles are placed in specific places in the measurement cross section and calculates voltage outputs for the individual sensors, is modelled The solutions from the forward problem are used to solve the inverse problem, which uses actual sensor voltage readings to estimate the spatial distribution of the material in the measurement cross section The solution of the inverse problem is used to derive the linear back projection (LBP) and filtered LBP algorithms In order to improve image quality, a hybrid reconstruction algorithm is implemented This algorithm first checks if any sensors read zero and sets (locks for this estimation) all pixels associated with them to zero (no material) The algorithm then proceeds as for the LBP

Further development of a tomographic imaging system using optical fibres for pneumatic conveyors

Abstract: This paper describes the further development of optical sensor hardware for a process tomography system in which emitters and detectors are used to exploit the optical characteristics of multiphase flow regimes. The optical arrangement is described and the importance of fibre beam position discussed. The proportion of the measurement volume interrogated by the beams is derived. The response of a single fibre is shown followed by a reconstructed concentration profile.

Concentration measurements of bubbles in a water column using an optical tomography system.

Abstract: Optical tomography provides a means for the determination of the spatial distribution of materials with different optical density in a volume by non-intrusive means. This paper presents results of concentration measurements of gas bubbles in a water column using an optical tomography system. A hydraulic flow rig is used to generate vertical air-water two-phase flows with controllable bubble flow rate. Two approaches are investigated. The first aims to obtain an average gas concentration at the measurement section, the second aims to obtain a gas distribution profile by using tomographic imaging. A hybrid back-projection algorithm is used to calculate concentration profiles from measured sensor values to provide a tomographic image of the measurement cross-section. The algorithm combines the characteristic of an optical sensor as a hard field sensor and the linear back projection algorithm.

Mass flow measurement of bulk solids in pneumatic pipelines

Abstract: Many types of techniques for metering the mass flow rate of bulk solids in a pneumatic pipeline have been proposed and developed during the past 20 years. This paper presents a detailed and comprehensive review of the techniques and the current state of knowledge and experience. The techniques are classified under three main categories: direct measurement of solids mass flow rates, measurement of volumetric concentrations of solids and measurement of solids velocity. Future developments and possible trends in this field are also included.

Impact of CSR and environmental triggers on employee green behavior: The mediating effect of employee well-being

Abstract: This article explores the influence of corporate social responsibility (CSR) and three green triggers of environment (awareness, concern, and knowledge) on employee well‐being and green behavior. The study engages the stimulus–organism–response model for testing the association between CSR and well‐being of employees that leads to employee green behavior. Furthermore, social exchange theory has been utilized to describe the association between well‐being and green behavior of employees. Data have been gathered through questionnaire from 509 employees working in guest‐service hotels of Pakistan. Structural equation modeling has been used to test the hypotheses. Findings show that CSR, environmental concern, and knowledge have positive effect on employee well‐being, whereas environmental awareness has positive but insignificant effect on employee well‐being. Furthermore, environmental concern, knowledge, and well‐being have a positive influence on green behavior, whereas CSR and environmental knowledge have a positive but insignificant effect. Moreover, well‐being fully mediates the relationship between CSR and green behavior and between environmental awareness and green behavior of employees. However, a partial mediation was observed between environmental concern and green behavior. The findings also indicate that no mediation was found between environmental knowledge and employee green behavior. The findings suggest that the hotel managers should invest to improve employee's awareness regarding green behavior by conducting environmental training for cultivating environmental knowledge and awareness. Moreover, CSR activities should be performed for attaining competitive edge and maintaining a balance between progress and sustainability of environment.

Non-Invasive Process Tomography in Chemical Mixtures - A Review

Abstract: Decades of research, visualizing and monitoring chemical mixtures in the process plant non-invasively plays an important role in making sure that the system produces a high quality product without disturbing the nature of the plant. In this case, process tomography can be applied for the chemical mixtures. Thus, the objective of this paper is to review the current research on non-invasive process tomography for detecting chemical mixtures based on hard-field and soft-field tomography. The discussion on liquid–liquid, liquid–solid and liquid–gas two-phase flow for every type of non-invasive process tomography is explained in detail. Consequently, non-invasive process tomography has expanded strongly in chemical applications. Finally, potential future research on the chemical mixture based on ERT is addressed.