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270 results on '"Wildman, R."'

1. Additively manufactured ultra-high vacuum chamber below $10^{-10}$ mbar

Author

Cooper, N., Coles, L. A., Everton, S., Campion, R. P., Madkhaly, S., Morley, C., Evans, W., Saint, R., Krüger, P., Oručević, F., Tuck, C., Wildman, R. D., Fromhold, T. M., and Hackermueller, L.

Subjects
Quantum Physics, Physics - Applied Physics
Abstract

Metal-based additive manufacturing (AM) represents a paradigm change in engineering and production methods across multiple industries and sectors. AM methods enable mass reduction and performance optimisation well beyond that achievable via conventional manufacturing, thereby impacting significantly on aerospace and space technologies. Technologies relying on high and ultra-high vacuum (UHV), such as x-ray photo-electron spectroscopy, photo-sensors, cameras and cryostats, could also benefit greatly from AM. Despite recent advances in AM processing of metals, additively manufactured UHV chambers have so far not been achieved. Reducing the mass of UHV equipment is particularly critical for the development of portable cold atom systems, which are expected to underpin the next generation of sensing and timekeeping technologies and to allow novel space-based sensors for fundamental research. We demonstrate here an additively manufactured UHV chamber reaching a pressure below $10^{-10}$ mbar, enabling a cloud of cold $^{85}$Rb atoms to be trapped - the starting point for many precision timekeeping and sensing devices. The chamber is manufactured from aluminium alloy AlSi10Mg by laser powder bed fusion and has a mass of less than a third of a commercially-available equivalent. Outgassing analysis based on mass spectrometry was performed and it was demonstrated that even without active pumping the system remains in the $10^{-9}$ mbar regime for up to 48 hours.

Published
2019
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2. 3D-printed components for quantum devices

Author

Saint, R., Evans, W., Zhou, Y., Fromhold, T. M., Saleh, E., Maskery, I., Tuck, C., Wildman, R., Oručević, F., and Krüger, P.

Subjects
Quantum Physics, Physics - Atomic Physics, Physics - Instrumentation and Detectors
Abstract

Recent advances in the preparation, control and measurement of atomic gases have led to new insights into the quantum world and unprecedented metrological sensitivities, e.g. in measuring gravitational forces and magnetic fields. The full potential of applying such capabilities to areas as diverse as biomedical imaging, non-invasive underground mapping, and GPS-free navigation can only be realised with the scalable production of efficient, robust and portable devices. Here we introduce additive manufacturing as a production technique of quantum device components with unrivalled design freedom, providing a step change in efficiency, compactness and facilitating systems integration. As a demonstrator we present a compact ultracold atom source using less than ten milliwatts power to produce large samples of cold rubidium gases in an ultrahigh vacuum environment. This disruptive technology opens the door to drastically improved integrated structures, which will further reduce power consumption, size and assembly complexity in scalable series manufacture of bespoke quantum devices., Comment: 7 pages, 6 figures

Published
2017

5. On the role of the Knudsen layer in rapid granular flows

Author

Galvin, J. E., Hrenya, C. M., and Wildman, R. D.

Subjects
Condensed Matter - Soft Condensed Matter
Abstract

A combination of molecular-dynamics simulations, theoretical predictions, and previous experiments are used in a two-part study to determine the role of the Knudsen layer in rapid granular flows. First, a robust criterion for the identification of the thickness of the Knudsen layer is established: a rapid deterioration in Navier-Stokes-order prediction of the heat flux is found to occur in the Knudsen layer. For (experimental) systems in which heat flux measurements are not easily obtained, a rule-of-thumb for estimating the Knudsen layer thickness follows, namely that such effects are evident within 2.5 (local) mean free paths of a given boundary. Second, comparisons of simulation and experimental data with Navier-Stokes order theory are used to provide a measure as to when Knudsen layer effects become non-negligible. Specifically, predictions that do not account for the presence of a Knudsen layer appear reliable for Knudsen layers collectively composing up to 20% of the domain, whereas deterioration of such predictions becomes apparent when the domain is fully comprised of the Knudsen layer., Comment: 9 figures, accepted to Journal of Fluid Mechanics

Published
2007
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27. A social history of Scottish working class education, 1800 to 1872, with particular reference to Glasgow

Author

Wildman, R. A.

Subjects
370.942
Abstract

The primary aim of this work is a study of the relationship between education and the process of industrialisation in nineteenth century Scotland. Although a fairly arbitrary starting date has been selected, the period can be conveniently labelled as the first phase of industrial capitalism, and it terminates with the emergence of the 1872 Education (Scotland) Act. To re-analyse education for the working class not by them, an institutional approach has been abandoned in favour of a sociological one. In a sense concentration upon the working class child, or young worker, encourages this approach as does the statistical analysis used. Children from 5 to 15 years of age appear throughout, on the assumption that it was the highest attainable point of school attendance under favourable circumstances. Both the supply and demand side of the educational equation are often considered together to prove that social stratification in Scottish education was complete before the 1870's. The central theoretical position borrows from the heritage of the Enlightenment, when social circumstances were discovered to mould the character of man. The most applicable social concept used is the concept of labour time. As the demands of the economy expressed as constraints upon the choices of the working class operate to affect attendance, enrolment, and the distribution of knowledge, knowledge thus becomes a question of time i.e. intellectual labour time (time spent upon gathering it) versus manual labour time (time spent at work to reproduce the working class family). Because knowledge here conceived is a function of time not intelligence, the working class are not less well educated because they are less intelligent, only less well educated because less time has been spent on cultivating the art. It is highlighted in the case-studies of transmitted educational deprivation where educational opportunity corresponds definitely with the state of economic circumstances of the parents.

Published
1977

34. Design of highly stabilized nanocomposite inks based on biodegradable polymer-matrix and gold nanoparticles for Inkjet Printing

Author

Begines, B., Alcudia, A., Aguilera-Velazquez, R., Martínez, G., He, Y., Wildman, R., Sayagués, María Jesús, Jimenez-Ruiz, Aila, Prado-Gotor, R., Begines, B., Alcudia, A., Aguilera-Velazquez, R., Martínez, G., He, Y., Wildman, R., Sayagués, María Jesús, Jimenez-Ruiz, Aila, and Prado-Gotor, R.

Abstract

Nowadays there is a worldwide growing interest in the Inkjet Printing technology owing to its potentially high levels of geometrical complexity, personalization and resolution. There is also social concern about usage, disposal and accumulation of plastic materials. In this work, it is shown that sugar-based biodegradable polyurethane polymers exhibit outstanding properties as polymer-matrix for gold nanoparticles composites. These materials could reach exceptional stabilization levels, and demonstrated potential as novel robust inks for Inkjet based Printing. Furthermore, a physical comparison among different polymers is discussed based on stability and printability experiments to search for the best ink candidate. The University of Seville logo was printed by employing those inks, and the presence of gold was confirmed by ToF-SIMS. This approach has the potential to open new routes and applications for fabrication of enhanced biomedical nanometallic-sensors using stabilized AuNP.

Published
2019

35. Insights into the mechanical properties of several triply periodic minimal surface lattice structures made by polymer additive manufacturing

Author

Mechanical Engineering, Maskery, I., Sturm, L., Aremu, A. O., Panesar, A., Williams, C. B., Tuck, C. J., Wildman, R. D., Ashcroft, I. A., Hague, R. J. M., Mechanical Engineering, Maskery, I., Sturm, L., Aremu, A. O., Panesar, A., Williams, C. B., Tuck, C. J., Wildman, R. D., Ashcroft, I. A., and Hague, R. J. M.

Abstract

Three-dimensional lattices have applications across a range of fields including structural lightweighting, impact absorption and biomedicine. In this work, lattices based on triply periodic minimal surfaces were produced by polymer additive manufacturing and examined with a combination of experimental and computational methods. This investigation elucidates their deformation mechanisms and provides numerical parameters crucial in establishing relationships between their geometries and mechanical performance. Three types of lattice were examined, with one, known as the primitive lattice, being found to have a relative elastic modulus over twice as large as those of the other two. The deformation process of the primitive lattice was also considerably different from those of the other two, exhibiting strut stretching and buckling, while the gyroid and diamond lattices deformed in a bending dominated manner. Finite element predictions of the stress distributions in the lattices under compressive loading agreed with experimental observations. These results can be used to create better informed lattice designs for a range of mechanical and biomedical applications. (C) 2017 The Authors. Published by Elsevier Ltd.

Published
2018

36. Hierarchical re-meshing strategies with mesh mapping for topology optimisation

Author

Panesar, A, Brackett, D, Ashcroft, I, Wildman, R, and Hague, R

Subjects
Mathematics, Interdisciplinary Applications, remeshing, Technology, octree decomposition, Science & Technology, Engineering, topology optimisation, Applied Mathematics, Physical Sciences, Engineering, Multidisciplinary, finite element analysis, Mathematics, 09 Engineering
Abstract

This work investigates the use of hierarchical mesh decomposition strategies for topology optimisation using bi‐directional evolutionary structural optimisation algorithm. The proposed method uses a dual mesh system that decouples the design variables from the finite element analysis mesh. The investigation focuses on previously unexplored areas of these techniques to investigate the effect of five meshing parameters on the analysis solving time (i.e. computational effort) and the analysis quality (i.e. solution optimality). The foreground mesh parameters, including adjacency ratio and minimum and maximum element size, were varied independently across solid and void domain regions. Within the topology optimisation, strategies for controlling the mesh parameters were investigated. The differing effects of these parameters on the efficiency and efficacy of the analysis and optimisation stages are discussed, and recommendations are made for parameter combinations. Some of the key findings were that increasing the adjacency ratio increased the efficiency only modestly – the largest effect was for the minimum and maximum element size parameters – and that the most dramatic reduction in solve time can be achieved by not setting the minimum element size too low, assuming mapping onto a background mesh with a minimum element size of 1.

Published
2016

37. UK National Quantum Technologies Hub in sensors and metrology

Author

Bongs, K., Boyer, V., Cruise, M. A., Freise, A., Holynski, M., Hughes, J., Kaushik, A., Lien, Y.-H., Niggebaum, A., Perea-Ortiz, M., Petrov, P., Plant, S., Singh, Y., Stabrawa, A., Paul, D. J., Sorel, M., Cumming, D. R. S., Marsh, J. H., Bowtell, R. W., Bason, M. G., Beardsley, R. P., Campion, R. P., Brookes, M. J., Fernholz, T., Fromhold, T. M., Hackermuller, L., Krüger, P., Li, X., Maclean, J. O., Mellor, C. J., Novikov, S. V., Orucevic, F., Rushforth, A. W., Welch, N., Benson, T. M., Wildman, R. D., Freegarde, T., Himsworth, M., Ruostekoski, J., Smith, P., Tropper, A., Griffin, P. F., Arnold, A. S., Riis, E., Hastie, J. E., Paboeuf, D., Parrotta, D. C., Garraway, B. M., Pasquazi, A., Peccianti, M., Hensinger, W., Potter, E., Nizamani, A. H., Bostock, H., Rodriguez Blanco, A., Sinuco-Leon, G., Hill, I. R., Williams, R. A., Gill, P., Hempler, N., Malcolm, G. P. A., Cross, T., Kock, B. O., Maddox, S., John, P., Stuhler, Jürgen, and Shields, Andrew J.

Subjects
QC
Abstract

The UK National Quantum Technology Hub in Sensors and Metrology is one of four flagship initiatives in the UK National of Quantum Technology Program. As part of a 20-year vision it translates laboratory demonstrations to deployable practical devices, with game-changing miniaturized components and prototypes that transform the state-of-the-art for quantum sensors and metrology. It brings together experts from the Universities of Birmingham, Glasgow, Nottingham, Southampton, Strathclyde and Sussex, NPL and currently links to over 15 leading international academic institutions and over 70 companies to build the supply chains and routes to market needed to bring 10–1000x improvements in sensing applications. It seeks, and is open to, additional partners for new application development and creates a point of easy open access to the facilities and supply chains that it stimulates or nurtures.

Published
2016

38. A New Photocrosslinkable Polycaprolactone based ink for 3D Inkjet Printing

Author

He, Y, Tuck, C J, Kilsby, S, Christie, S, Edmondson, Stephen, Hague, R J M, Rose, F R A J, and Wildman, R D

Abstract

A new type of photocrosslinkable Polycaprolactone (PCL) based ink that is suitable for 3D inkjet printing has been developed. Photocrosslinkable PCL dimethylacrylate was synthesized and mixed with Poly(ethylene glycol) di-acrylate (PEGDA) to prepare an ink with a suitable viscosity for inkjet printing. The ink performance under different printing environments, initiator concentrations and post-process was studied. This showed that a Nitrogen atmosphere during printing was beneficial for curing and material property optimisation, as well as improving the quality of structures produced. A simple structure, building in the z direction, demonstrated the potential for this material for the production of 3D printed objects. Cells testwas carried out to investigate the biocompatibility of the developed ink.

Published
2016
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39. Multimaterial Manufacture Through Combining Optical Tweezers with Multiphoton Fabrication.

Author

Askari, M., Tuck, C. J., Hu, Q., Hague, R. J. M., and Wildman, R. D.

Subjects
OPTICAL tweezers, MANUFACTURING processes, THREE-dimensional printing, LASER pulses, ULTRA-short pulsed lasers, POLYMERIZATION, LASERS
Abstract

Multi-Photon Polymerization (MPP) is a technique used to fabricate complex micro-scale 3D structures using ultra-short laser pulses. Typically, MPP is used to manufacture micron-scale components in photopolymer materials. However, the development of micron scale processes that can produce components from multiple materials within a single manufacturing step would be advantageous. This would allow the inclusion of particles that are manipulated and embedded within structures with sub-micron feature sizes. To achieve this, an MPP system was combined with an optical trapping (OT) setup in order to independently manipulate microparticles in the x, y and z planes. Particles were transported into the fabrication site using the OT and encapsulated using the MPP laser. Here it is shown that combining the OT capabilities with an additive manufacturing technique enables the production of complex multi-material artifacts. [ABSTRACT FROM AUTHOR]

Published
2019
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41. The UK National Quantum Technologies Hub in sensors and metrology (Keynote Paper)

Author

Bongs, K., Boyer, V., Cruise, M.A., Freise, A., Holynski, M., Hughes, J., Kaushik, A., Lien, Y.H., Niggebaum, A., Perea-Ortiz, M., Petrov, P., Plant, S., Singh, Y., Stabrawa, A., Paul, D.J., Sorel, M., Cumming, D.R.S., Marsh, J.H., Bowtell, R.W., Bason, M.G., Beardsley, R.P., Campion, R.P., Brookes, M.J., Fernholz, T., Fromhold, T.M., Hackermuller, L., Krüger, P., Li, X., Maclean, J.O., Mellor, C.J., Novikov, S.V., Orucevic, F., Rushforth, A.W., Welch, N., Benson, T.M., Wildman, R. D., Freegarde, T., Himsworth, M., Ruostekoski, J., Smith, Peter, Tropper, A., Griffin, P.F., Arnold, A.S., Riis, E., Hastie, J.E., Paboeuf, D., Parrotta, D.C., Garraway, B.M., Pasquazi, A., Peccianti, M., Hensinger, W., Potter, E., Nizamani, A.H., Bostock, H., Rodriguez Blanco, A., Sinuco-Leon, G., Hill, I.R., Williams, R.A., Gill, P., Hempler, N., Malcolm, G.P.A., Cross, T., Kock, B.O., Maddox, S., John, P., Bongs, K., Boyer, V., Cruise, M.A., Freise, A., Holynski, M., Hughes, J., Kaushik, A., Lien, Y.H., Niggebaum, A., Perea-Ortiz, M., Petrov, P., Plant, S., Singh, Y., Stabrawa, A., Paul, D.J., Sorel, M., Cumming, D.R.S., Marsh, J.H., Bowtell, R.W., Bason, M.G., Beardsley, R.P., Campion, R.P., Brookes, M.J., Fernholz, T., Fromhold, T.M., Hackermuller, L., Krüger, P., Li, X., Maclean, J.O., Mellor, C.J., Novikov, S.V., Orucevic, F., Rushforth, A.W., Welch, N., Benson, T.M., Wildman, R. D., Freegarde, T., Himsworth, M., Ruostekoski, J., Smith, Peter, Tropper, A., Griffin, P.F., Arnold, A.S., Riis, E., Hastie, J.E., Paboeuf, D., Parrotta, D.C., Garraway, B.M., Pasquazi, A., Peccianti, M., Hensinger, W., Potter, E., Nizamani, A.H., Bostock, H., Rodriguez Blanco, A., Sinuco-Leon, G., Hill, I.R., Williams, R.A., Gill, P., Hempler, N., Malcolm, G.P.A., Cross, T., Kock, B.O., Maddox, S., and John, P.

Abstract

The UK National Quantum Technology Hub in Sensors and Metrology is one of four flagship initiatives in the UK National of Quantum Technology Program. As part of a 20-year vision it translates laboratory demonstrations to deployable practical devices, with game-changing miniaturized components and prototypes that transform the state-of-the-art for quantum sensors and metrology. It brings together experts from the Universities of Birmingham, Glasgow, Nottingham, Southampton, Strathclyde and Sussex, NPL and currently links to over 15 leading international academic institutions and over 70 companies to build the supply chains and routes to market needed to bring 10-1000x improvements in sensing applications. It seeks, and is open to, additional partners for new application development and creates a point of easy open access to the facilities and supply chains that it stimulates or nurtures.

Published
2016

42. The UK National Quantum Technologies Hub in sensors and metrology (Keynote Paper)

Author

Bongs, K., additional, Boyer, V., additional, Cruise, M. A., additional, Freise, A., additional, Holynski, M., additional, Hughes, J., additional, Kaushik, A., additional, Lien, Y.-H., additional, Niggebaum, A., additional, Perea-Ortiz, M., additional, Petrov, P., additional, Plant, S., additional, Singh, Y., additional, Stabrawa, A., additional, Paul, D. J., additional, Sorel, M., additional, Cumming, D. R. S., additional, Marsh, J. H., additional, Bowtell, R. W., additional, Bason, M. G., additional, Beardsley, R. P., additional, Campion, R. P., additional, Brookes, M. J., additional, Fernholz, T., additional, Fromhold, T. M., additional, Hackermuller, L., additional, Krüger, P., additional, Li, X., additional, Maclean, J. O., additional, Mellor, C. J., additional, Novikov, S. V., additional, Orucevic, F., additional, Rushforth, A. W., additional, Welch, N., additional, Benson, T. M., additional, Wildman, R. D., additional, Freegarde, T., additional, Himsworth, M., additional, Ruostekoski, J., additional, Smith, P., additional, Tropper, A., additional, Griffin, P. F., additional, Arnold, A. S., additional, Riis, E., additional, Hastie, J. E., additional, Paboeuf, D., additional, Parrotta, D. C., additional, Garraway, B. M., additional, Pasquazi, A., additional, Peccianti, M., additional, Hensinger, W., additional, Potter, E., additional, Nizamani, A. H., additional, Bostock, H., additional, Rodriguez Blanco, A., additional, Sinuco-Leon, G., additional, Hill, I. R., additional, Williams, R. A., additional, Gill, P., additional, Hempler, N., additional, Malcolm, G. P. A., additional, Cross, T., additional, Kock, B. O., additional, Maddox, S., additional, and John, P., additional

Published
2016
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45. Indices of abdominal obesity are better discriminators of cardiovascular risk factors than BMI: a meta-analysis

Author

Lee, Crystal, Huxley, Rachel, Wildman, R., Woodward, M., Lee, Crystal, Huxley, Rachel, Wildman, R., and Woodward, M.

Abstract

Objective: To determine which simple index of overweight and obesity is the best discriminator of cardiovascular risk factors. Study Design and Setting: This is a meta-analysis of published literature. MEDLINE was searched. Studies that used receiver-operating characteristics (ROC) curve analysis and published area under the ROC curves (AUC) for overweight and obesity indices with hypertension, type-2 diabetes, and/or dyslipidemia were included. The AUC for each of the four indices, with each risk factor, was pooled using a random-effects model; male and female data were analyzed separately. Results: Ten studies met the inclusion criteria. Body mass index (BMI) was the poorest discriminator for cardiovascular risk factors. Waist-to-height ratio (WHtR) was the best discriminator for hypertension, diabetes, and dyslipidemia in both sexes; its pooled AUC (95% confidence intervals) ranged from 0.67 (0.64, 0.69) to 0.73 (0.70, 0.75) and from 0.68 (0.63, 0.72) to 0.76 (0.70, 0.81) in males and females, respectively. Conclusion: Statistical evidence supports the superiority of measures of centralized obesity, especially WHtR, over BMI, for detecting cardiovascular risk factors in both men and women. © 2008 Elsevier Inc. All rights reserved.

Published
2008

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