Plasma simulation using the massively parallel processor

Two dimensional electrostatic simulation codes using the particle-in-cell model are developed on the Massively Parallel Processor (MPP). The conventional plasma simulation procedure that computes electric fields at particle positions by means of a gridded system is found inefficient on the MPP. The MPP simulation code is thus based on the gridless system in which particles are assigned to processing elements and electric fields are computed directly via Discrete Fourier Transform. Currently, the gridless model on the MPP in two dimensions is about nine times slower that the gridded system on the CRAY X-MP without considering I/O time. However, the gridless system on the MPP can be improved by incorporating a faster I/O between the staging memory and Array Unit and a more efficient procedure for taking floating point sums over processing elements. The initial results suggest that the parallel processors have the potential for performing large scale plasma simulations

Pseudo-pulse-Echo Mode Focused Rayleigh Wave EMATs for High Resolution Imaging of Surface-breaking Defects

Electromagnetic Acoustic Transducers (EMATs) are useful in Non-Destructive Testing as they can be used at lift-off on hot, moving, and rusted surfaces while being relatively inexpensive and robust. Generation of ultrasound using EMATs is relatively inefficient, however, the amplitude of the signal at a defect can be greatly improved with the use of focusing. A focused Rayleigh wave EMAT has been designed, characterized, and used to size a range of surface breaking defects in aluminum. The EMAT has improved spatial resolution compared to unfocused designs and generates a strong signal (giving up to 30 dB SNR) at the focal point, with a narrow beam width of 3.0 ± 0.5 mm. The new EMAT was used to detect and size a set of 1 mm width, 0.5 mm depth drilled slot defects, with lengths between 1 and 11 mm. The aperture angle of the coil was found to change the focal depth, as expected, however, variation of the aperture angle also shifts the focal point. This can be used to design EMAT coils with specified focal points, beam widths, and length of focal region to allow scans to be done at a chosen resolution. The EMAT was fully studied experimentally and using finite element modelling, and the coil design was optimized

Focused Rayleigh wave EMAT for characterisation of surface-breaking defects

Developments towards higher resolution and the ability to detect small defects are bringing a step-change in non-destructive testing. This paper presents a new method for increasing resolution, using a focused electromagnetic acoustic transducer (EMAT) optimised to generate Rayleigh waves at 2 MHz. This high frequency allows detection of mm-depth defects, and the focusing allows sizing of much shorter defects than is possible when using standard EMATs. The focusing behaviour and the aperture angle effect are analysed using laser vibrometry and finite element modeling, showing that a reduced aperture shifts the focal point from the designed value and increases the focal depth. The dual-EMAT has excellent signal to noise ratio (up to 30 dB) and has been used in single shot mode to image a variety of surface-breaking defects, including detecting and positioning a pair of real defects in an aluminium billet sample, and a machined defect of 2 mm length, 0.2 mm width, and 1.5 mm depth, giving an upper limit on the defect length of 2.1 +- 0.5 mm. The results can be used to design an EMAT with optimised focal behaviour for defect detection

Identifying the early adopters of alternative fuel vehicles: a case study of Birmingham, United Kingdom

The transport sector has been identified as a significant contributor to greenhouse gas emissions. As part of its emissions reduction strategy, the United Kingdom Government is demonstrating support for new vehicle technologies, paying attention, in particular, to electric vehicles. Cluster analysis was applied to Census data in order to identify potential alternative fuel vehicle drivers in the city of Birmingham, United Kingdom. The clustering was undertaken based on characteristics of age, income, car ownership, home ownership, socio-economic status and education. Almost 60% of areas that most closely fitted the profile of an alternative fuel vehicle driver were found to be located across four wards furthest from Birmingham city centre, while the areas with the poorest fit were located towards the centre of Birmingham. The paper demonstrates how Census data can be used in the initial stages of identifying potential early adopters of alternative vehicle drivers. It also shows how such research can provide scope for infrastructure planning and policy development for local and national authorities, while also providing useful marketing information to car manufacturers

The effect of EMAT coil geometry on the Rayleigh wave frequency behaviour

Understanding of optimal signal generation and frequency content for electromagnetic acoustic transducers (EMATs) is key to improving their design and signal to noise ratio. Linear and meander coil designs are fairly well understood, but other designs such as racetrack or focused coils have recently been proposed. Multiple transmission racetrack coil EMATs, with focused and unfocused designs, were constructed. The optimum driving frequency for maximum detected signal was found to range between 1.1 and 1.4 MHz on aluminium for a 1.5 mm width coil. A simple analytical model based on the instantaneous velocity of a wave predicts a maximum signal at 1.44 MHz. Modelling the detection coil as a spatial square wave agrees with this, and predicts a general relation of f =0.761v/L between the optimum frequency f , the wave velocity v, and the coil width L. A time domain model of the detection coil predicts a 1.4-1.5 MHz peak for continuous wave excitation, with a frequency that decreases as the length of the wavepacket is decreased, consistent with the experimental data. Linear coil modelling using the same technique is shown to be consistent with previous work, with improving detection at lower wave frequencies, and signal minima at every integer multiple of the wavelength. Finite Element Analysis (FEA) is used to model the effects of the spatial width of the racetrack generation coil and focused geometry, and no significant difference is found between the focused and the unfocused EMAT response. This highlights the importance of designing the EMAT coil for the correct lift-off and desired frequency of operation. [Abstract copyright: Copyright © 2019 Elsevier B.V. All rights reserved.

Energy consumption and capacity utilization of galvanizing furnaces

An explicit equation leading to a method for improving furnace efficiency is presented. This equation is dimensionless and can be applied to furnaces of any size and fuel type for the purposes of comparison. The implications for current furnace design are discussed. Currently the technique most commonly used to reduce energy consumption in galvanizing furnaces is to increase burner turndown. This is shown by the analysis presented here actually to worsen the thermal efficiency of the furnace, particularly at low levels of capacity utilization. Galvanizing furnaces are different to many furnaces used within industry, as a quantity of material (in this case zinc) is kept molten within the furnace at all times, even outside production periods. The dimensionless analysis can, however, be applied to furnaces with the same operational function as a galvanizing furnace, such as some furnaces utilized within the glass industry. © IMechE 2004

Creative haptics: an evaluation of a haptic tool for non-sighted and visually impaired design students, studying at a distance

Design students who are blind or sight-impaired face distinct challenges when studying a visually centric discipline such as design practice. Students who are sighted use computer-aided design (CAD) which is presented via high definition using a PC mouse. However, design students who are blind or sight-impaired are not able to use visual display technology; therefore, this creates a barrier to access for this community. The aim of this study is to present a haptic prototype trial (Haptic Application Prototype Test [HAPT]) designed to assist design students who are blind/sight-impaired to interact with prototype assembly at the Open University (OU). The study specifically assessed the user feedback and the efficacy of access to CAD interface through the affordances of the haptic interface. The experiment included two groups of participants: one group included students who were blind and sight-impaired and the second group students who were classed fully sighted. Both groups were tested in two conditions of haptic engagement – manual and virtual. The parameters examined were (a) time – set at an industry-recognized time taken to assemble a ‘sketch model’ or prototype, and (b) ncollision – the number of collisions created by a collision algorithm which calculated any random collisions with the virtual environment or objects therein. Quantitative results showed that there was little statistical difference between time and a between-group test. From this we can imply that the haptic interface had offered equal access to CAD for people in the trial who were sighted and blind/sight-impaired indiscriminate of their sight acuity. Further future work using HAPT could be developed to a wider audience and a larger more diverse range of sight-impaired users. Future work will focus on new explorations of teaching using of haptics for greater immersion for distance learners at the OU science, technology, engineering and mathematics (STEM) labs

Identifying the early adopters of alternative fuel vehicles: A case study of Birmingham, United Kingdom

This article was published in the journal, Transportation Research Part A: Policy and Practice [© Elsevier]. The definitive version is available at: http://dx.doi.org/10.1016/j.tra.2012.05.004The transport sector has been identified as a significant contributor to greenhouse gas emissions. As part of its emissions reduction strategy, the United Kingdom Government is demonstrating support for new vehicle technologies, paying attention, in particular, to electric vehicles. Cluster analysis was applied to Census data in order to identify potential alternative fuel vehicle drivers in the city of Birmingham, United Kingdom. The clustering was undertaken based on characteristics of age, income, car ownership, home ownership, socio-economic status and education. Almost 60% of areas that most closely fitted the profile of an alternative fuel vehicle driver were found to be located across four wards furthest from Birmingham city centre, while the areas with the poorest fit were located towards the centre of Birmingham. The paper demonstrates how Census data can be used in the initial stages of identifying potential early adopters of alternative vehicle drivers. It also shows how such research can provide scope for infrastructure planning and policy development for local and national authorities, while also providing useful marketing information to car manufacturers

Particle motion and heat transfer in an upward-flowing dense particle suspension: application in solar receivers

Concentrated solar power (CSP) plants conventionally make use of molten salt as the heat transfer medium, which transfers heat between the solar receiver and a steam turbine power circuit. A new approach uses particles of a heat-resistant particulate medium in the form of many dense upward-moving fluidised beds contained within an array of vertical tubes within the solar receiver. In most dense gas-solid fluidisation systems, particle circulation is induced by bubble motion and is the primary cause of particle convective heat transfer, which is the major contributing mechanism to overall heat transfer. The current work describes experiments designed to investigate the relationship between this solids convection and the heat transfer coefficient between the bed and the tube wall, which is shown to depend on the local particle concentration and their rate of renewal at the wall. Experiments were performed using 65 µm silicon carbide particles in a tube of diameter 30mm, replicating the conditions used in the real application. Solids motion and time-averaged solids concentration were measured using Positron Emission Particle Tracking (PEPT) and local heat transfer coefficients measured using small probes which employ electrical resistance heating and thermocouple temperature measurement. Results show that, as for other types of bubbling beds, the heat transfer coefficient first increases as the gas flow rate increases (because the rate of particle renewal at the wall increases), before passing through a maximum and decreasing again as the reducing local solids concentration at the wall becomes the dominant effect. Measured heat transfer coefficients are compared with theoretical approaches by Mickley and Fairbanks packet model and Thring correlation. The close correspondence between heat transfer coefficient and solids movement is here demonstrated by PEPT for the first time in a dense upward-moving fluidised bed

Heterogeneously catalyzed lignin depolymerization

Biomass offers a unique resource for the sustainable production of bio-derived chemical and fuels as drop-in replacements for the current fossil fuel products. Lignin represents a major component of lignocellulosic biomass, but is particularly recalcitrant for valorization by existing chemical technologies due to its complex cross-linking polymeric network. Here, we highlight a range of catalytic approaches to lignin depolymerisation for the production of aromatic bio-oil and monomeric oxygenates