As part of an on going study of the process physics of flexographic printing, a comprehensive stu... more As part of an on going study of the process physics of flexographic printing, a comprehensive study has been undertaken of the effect of ink viscosity, engagement, line ruling and anilox volume on the ink transfer to paper. The viscosity of the ink was varied in two manners, one by dilution with solvent reduced pigment concentration as well as the viscosity and the other reducing the viscosity at constant ink strength. The anilox volume was found to have the greatest effect on the ink transfer in the solid coverage areas. However, in interaction was found between the coverage, the line ruling and the anilox cell size. This can be attributed to the deformation of the half tone areas of the plate into the anilox cells and in part explain the inconsistency found by previous researchers in highlight regions on the plate. The engagement was found to increase the ink transfer as more ink was impressed into the substrate
19 DEVELOPMENT OF TIN DIOXIDE BASED EXHAUST SENSORS PG Eastwood , TC Claypole , J Watson Universi... more 19 DEVELOPMENT OF TIN DIOXIDE BASED EXHAUST SENSORS PG Eastwood , TC Claypole , J Watson University College Swansea, UK SUMMARY Potential applications for new solid-state exhaust sensors are examined, with particular reference to catalytic converters. ...
This study concentrates on the influence of the levels of swirl on the aerodynamics and NO/sub x/... more This study concentrates on the influence of the levels of swirl on the aerodynamics and NO/sub x/ emissions at a constant load. Measurements of mean temperature, local velocity and NO-NO/sub x/ concentrations were taken for swirl numbers from .63 to 3.04. From these a net NO/sub x/ flow through sections of the flame were calculated. The flames have been classified into 4 broad groups dependent on the influence of the recirculation zone on flame stabilization. These changes in flame type coincide with other changes in the flow structure, as can be seen from the effects on the precessing vortex core. A model based on well stirred and plug flow reactors is proposed for the flows. The results highlight errors in interpretation that can occur by only considering the concentration measurements. In order to establish the source of pollutants in a swirl combustor, it is essential to consider the pollutant mass flow profiles. 17 refs.
The laser doppler anemometer is a comparatively new tool for flow measurements. This article outl... more The laser doppler anemometer is a comparatively new tool for flow measurements. This article outlines the principles behind 'dual-beam' laser anemometry using the fringe model and relates the role of l.d.a. in fluid dynamics research. The techniques are illustrated with reference to systems available at University College, Cardiff Laser doppler anemometry is a comparatively new tool for flow measurements. Of its many advantages over conventional techniques, its response to turbulent flows and its non-intrusion into the measurement section, thus not introducing additional phenomema to those under study, have led to is application in most fields of fluid dynamics. The majority of work wascarried out in the late 1960s and early 1970s at Imperial College, London, 1~3 though the development and refinement is still the subject of on going research. However, as well as these prototype systems, there are now becoming available increasing numbers of commercially produced systems. The principles behind the 'dual-beam' laser doppler anemometer are outlined. Although there are other configurations, this is the one in most common use and the descriptions are made with reference to systems available at University College, Cardiff. Optics A typical arrangement for the optics in a dual-beam laser anemometer is shown in Fig. 1. The laser used is typically 15-35 mW, and though higher power lasers have been used, recentworkhasbeenaimedatreducing the required power by improved optics and signal processing. This leads to lower costs and greater safety. The beam from the laser is split using a diffraction grating. This produces a whole range of beams of which all but the two most powerful are masked off. These two beams are focused to run parallel to each other by a first lens. This enables the second lens, which deviates the Timothy Claypole, aged 24, is a research assistant at University College, Cardiff, investigating pollutant formation in swirling flames
Screen-printed thin-film batteries comprise of current collectors typically realised with commerc... more Screen-printed thin-film batteries comprise of current collectors typically realised with commercially available conductive silver inks primarily designed for non-critical printed electronics applications. The avoidance of electrochemical interaction of metallic silver with the respective battery chemistry requires printing of an additional passivation layer. The wide range of printing inks available makes it difficult for researchers to select and qualify battery specific inks that ensure a long-life cycle without limitation of relevant battery performance parameters. This study presents a novel method to quantify the passivation capability of carbon black passivation layers for silver current collectors in 6.0 M potassium hydroxide and 5.8 M zinc chloride aqueous electrolyte solutions. Cyclic voltammetry is used to determine possible electrochemical interaction of passivated current collectors with the electrolyte media which constitute battery performance degrading parasitic side reactions. An innovative approach based on Faraday's law of electrolysis is presented to transform cyclic voltammogram curve progressions into comparable numerical values. The mathematical approach allows quantitative comparison of individually fabricated passivation layers with respect to their passivation capability instead of interpreting a large number of cyclic voltammograms.
Development and characterization of a wire-plate air bubbling plasma for wastewater treatment usi... more Development and characterization of a wire-plate air bubbling plasma for wastewater treatment using nanosecond pulsed high voltage
ABSTRACT Through combined experimental and numerical investigation, the applicability of various ... more ABSTRACT Through combined experimental and numerical investigation, the applicability of various constitutive models for predicting the nonlinear stress–strain behaviour of three silicone rubber compounds was explored under conditions that are relevant to the large deformations that are encountered in the pad printing process. The effectiveness of the proposed model was tested against experiments on silicone rubber specimens. In application, the model exhibited very good agreement between the predicted force level and that measured on the pad press, and it provides new insight into the contact evolution during the ink transfer cycle. The results have shown that hardness as well as friction affects the pad distortion and, hence, the image dimensions that are critical for applications such as printing functional devices.
In order to examine new potential markets for printed electronics, a research study was undertake... more In order to examine new potential markets for printed electronics, a research study was undertaken to understand the performance of opaque substrate electroluminescent (EL) lamps. Opaque EL lamps are made possible by a PEDOT:PSS top electrode which replaces the ITO used in the conventional lamps. Screen-printed lamps were manufactured Coleg Cymraeg Cenedlaethol
As part of an on going study of the process physics of flexographic printing, a comprehensive stu... more As part of an on going study of the process physics of flexographic printing, a comprehensive study has been undertaken of the effect of ink viscosity, engagement, line ruling and anilox volume on the ink transfer to paper. The viscosity of the ink was varied in two manners, one by dilution with solvent reduced pigment concentration as well as the viscosity and the other reducing the viscosity at constant ink strength. The anilox volume was found to have the greatest effect on the ink transfer in the solid coverage areas. However, in interaction was found between the coverage, the line ruling and the anilox cell size. This can be attributed to the deformation of the half tone areas of the plate into the anilox cells and in part explain the inconsistency found by previous researchers in highlight regions on the plate. The engagement was found to increase the ink transfer as more ink was impressed into the substrate
19 DEVELOPMENT OF TIN DIOXIDE BASED EXHAUST SENSORS PG Eastwood , TC Claypole , J Watson Universi... more 19 DEVELOPMENT OF TIN DIOXIDE BASED EXHAUST SENSORS PG Eastwood , TC Claypole , J Watson University College Swansea, UK SUMMARY Potential applications for new solid-state exhaust sensors are examined, with particular reference to catalytic converters. ...
This study concentrates on the influence of the levels of swirl on the aerodynamics and NO/sub x/... more This study concentrates on the influence of the levels of swirl on the aerodynamics and NO/sub x/ emissions at a constant load. Measurements of mean temperature, local velocity and NO-NO/sub x/ concentrations were taken for swirl numbers from .63 to 3.04. From these a net NO/sub x/ flow through sections of the flame were calculated. The flames have been classified into 4 broad groups dependent on the influence of the recirculation zone on flame stabilization. These changes in flame type coincide with other changes in the flow structure, as can be seen from the effects on the precessing vortex core. A model based on well stirred and plug flow reactors is proposed for the flows. The results highlight errors in interpretation that can occur by only considering the concentration measurements. In order to establish the source of pollutants in a swirl combustor, it is essential to consider the pollutant mass flow profiles. 17 refs.
The laser doppler anemometer is a comparatively new tool for flow measurements. This article outl... more The laser doppler anemometer is a comparatively new tool for flow measurements. This article outlines the principles behind 'dual-beam' laser anemometry using the fringe model and relates the role of l.d.a. in fluid dynamics research. The techniques are illustrated with reference to systems available at University College, Cardiff Laser doppler anemometry is a comparatively new tool for flow measurements. Of its many advantages over conventional techniques, its response to turbulent flows and its non-intrusion into the measurement section, thus not introducing additional phenomema to those under study, have led to is application in most fields of fluid dynamics. The majority of work wascarried out in the late 1960s and early 1970s at Imperial College, London, 1~3 though the development and refinement is still the subject of on going research. However, as well as these prototype systems, there are now becoming available increasing numbers of commercially produced systems. The principles behind the 'dual-beam' laser doppler anemometer are outlined. Although there are other configurations, this is the one in most common use and the descriptions are made with reference to systems available at University College, Cardiff. Optics A typical arrangement for the optics in a dual-beam laser anemometer is shown in Fig. 1. The laser used is typically 15-35 mW, and though higher power lasers have been used, recentworkhasbeenaimedatreducing the required power by improved optics and signal processing. This leads to lower costs and greater safety. The beam from the laser is split using a diffraction grating. This produces a whole range of beams of which all but the two most powerful are masked off. These two beams are focused to run parallel to each other by a first lens. This enables the second lens, which deviates the Timothy Claypole, aged 24, is a research assistant at University College, Cardiff, investigating pollutant formation in swirling flames
Screen-printed thin-film batteries comprise of current collectors typically realised with commerc... more Screen-printed thin-film batteries comprise of current collectors typically realised with commercially available conductive silver inks primarily designed for non-critical printed electronics applications. The avoidance of electrochemical interaction of metallic silver with the respective battery chemistry requires printing of an additional passivation layer. The wide range of printing inks available makes it difficult for researchers to select and qualify battery specific inks that ensure a long-life cycle without limitation of relevant battery performance parameters. This study presents a novel method to quantify the passivation capability of carbon black passivation layers for silver current collectors in 6.0 M potassium hydroxide and 5.8 M zinc chloride aqueous electrolyte solutions. Cyclic voltammetry is used to determine possible electrochemical interaction of passivated current collectors with the electrolyte media which constitute battery performance degrading parasitic side reactions. An innovative approach based on Faraday's law of electrolysis is presented to transform cyclic voltammogram curve progressions into comparable numerical values. The mathematical approach allows quantitative comparison of individually fabricated passivation layers with respect to their passivation capability instead of interpreting a large number of cyclic voltammograms.
Development and characterization of a wire-plate air bubbling plasma for wastewater treatment usi... more Development and characterization of a wire-plate air bubbling plasma for wastewater treatment using nanosecond pulsed high voltage
ABSTRACT Through combined experimental and numerical investigation, the applicability of various ... more ABSTRACT Through combined experimental and numerical investigation, the applicability of various constitutive models for predicting the nonlinear stress–strain behaviour of three silicone rubber compounds was explored under conditions that are relevant to the large deformations that are encountered in the pad printing process. The effectiveness of the proposed model was tested against experiments on silicone rubber specimens. In application, the model exhibited very good agreement between the predicted force level and that measured on the pad press, and it provides new insight into the contact evolution during the ink transfer cycle. The results have shown that hardness as well as friction affects the pad distortion and, hence, the image dimensions that are critical for applications such as printing functional devices.
In order to examine new potential markets for printed electronics, a research study was undertake... more In order to examine new potential markets for printed electronics, a research study was undertaken to understand the performance of opaque substrate electroluminescent (EL) lamps. Opaque EL lamps are made possible by a PEDOT:PSS top electrode which replaces the ITO used in the conventional lamps. Screen-printed lamps were manufactured Coleg Cymraeg Cenedlaethol
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