Measurements of the Secondary Electron Emission from Rare Gases at 4.2K

Dependence of the secondary electron yield (SEY) from the primary beam incident energy and the coverage has been measured for neon, argon, krypton and xenon condensed on a target at 4.2K. The beam energy ranged between 100 eV and 3 keV, the maximal applied coverage have made up 12000, 4700, 2500 and 1400 monolayers correspondingly for neon, argon, krypton and xenon. The SEY results for these coverages can be considered as belonging only to investigated gases without influence of the target material. The SEY dependencies versus the primary beam energy for all gases comprise only an ascending part and therefore, the maximal measured SEY values have been obtained for the beam energy of 3keV and have made up 62, 73, 60.5 and 52 for neon, argon, krypton and xenon correspondingly. Values of the first cross-over have made up 21 eV for neon, 14 eV for argon, 12.5 eV for krypton and 10.5 eV for xenon. An internal field appearing across a film due to the beam impact can considerably affect the SEY measurements that demanded the beam current to be reduced till 9.0E-10A. Duration of the beam impact varied between 500 \mu sec and 250 \mu sec. It was found that reliable SEY measurements can also be taken on a charged surface if the charge was acquired due to beam impact with electrons of higher energy. All SEY measurements for once applied coverage have been carried out for whole range of incident energies from 3 keV down to 100 eV without renewing the film. Developing of pores inside of a deposited film can significantly increase the SEY as it was observed during warming up the target.Comment: 10 Pages - 25 figure

Measurements of the Secondary Electron Emission of Some Insulators

Charging up the surface of an insulator after beam impact can lead either to reverse sign of field between the surface and collector of electrons for case of thick sample or appearance of very high internal field for thin films. Both situations discard correct measurements of secondary electron emission (SEE) and can be avoided via reducing the beam dose. The single pulse method with pulse duration of order of tens microseconds has been used. The beam pulsing was carried out by means of an analog switch introduced in deflection plate circuit which toggles its output between "beam on" and "beam off" voltages depending on level of a digital pulse. The error in measuring the beam current for insulators with high value of SEE was significantly reduced due to the use for this purpose a titanium sample having low value of the SEE with DC method applied. Results obtained for some not coated insulators show considerable increase of the SEE after baking out at 3500C what could be explained by the change of work function. Titanium coatings on alumina exhibit results close to the ones for pure titanium and could be considered as an effective antimultipactor coating.Comment: 8 pages, 13 figure

Human factors in the display and use of aeronautic information from different sources and of different status.

In aeronautic operations and maintenance a large amount of information is provided by documentation and instruments which is needed for the safe operation of an aircraft. However, a development is taking place towards the use of multiple sources, with information being integrated in one display, and the construction of meaningful knowledge in interaction with the user, providing support for decision making and diagnostics. Combining information from different sources means that information could differ in status, age and certainty. The advantage of combining information is in providing the user with a clear picture of the situation, highlighting information that is context-relevant, and ensuring all available information is provided. A wide range of human factors issues is related to perceiving, interpreting and using information from different sources and of different statuses. Cases from different studies are presented in order to address common human factors and design recommendations. These studies deal with the development of demonstrators of information presentation as well as interviews and evaluations with users. Topics include maintenance manuals connected to aircraft systems, electronic flightbags, and cockpit displays. The paper addresses the human factors issues identified, and indicates directions for solutions for information presentation, such as layered information, contextualisation, and integrated information

Creation and luminescence of size-selected gold nanorods

Fluorescent metal nanoparticles have attracted great interest in recent years for their unique properties and potential applications. Their optical behaviour depends not only on size but also on shape, and will only be useful if the morphology is stable. In this work, we produce stable size-selected gold nanorods (aspect ratio 1-2) using a size-selected cluster source and correlate their luminescence behaviour with the particle shape. Thermodynamic modelling is used to predict the preferred aspect ratio of 1.5, in agreement with the observations, and confirms that the double-icosahedron observed in experiments is significantly lower in energy than the alternatives. Using these samples a fluorescence lifetime imaging microscopy study observed two photon luminescence from nanoparticle arrays and a fast decay process (<100 ps luminescence lifetime), which are similar to those found from ligand stabilized gold nanorods under the same measurement conditions, indicating that a surface plasmon enhanced two-photon excitation process is still active at these small sizes. By further reducing the nanoparticle size, this approach has the potential to investigate size-dependent luminescence behaviour at smaller sizes than has been possible before

Remote sensing of cloud properties using ground-based measurements of zenith radiance

We have conducted the first extensive field test of two new methods to retrieve optical properties for overhead clouds that range from patchy to overcast. The methods use measurements of zenith radiance at 673 and 870 nm wavelengths and require the presence of green vegetation in the surrounding area. The test was conducted at the Atmospheric Radiation Measurement Program Oklahoma site during September–November 2004. These methods work because at 673 nm (red) and 870 nm (near infrared (NIR)), clouds have nearly identical optical properties, while vegetated surfaces reflect quite differently. The first method, dubbed REDvsNIR, retrieves not only cloud optical depth τ but also radiative cloud fraction. Because of the 1-s time resolution of our radiance measurements, we are able for the first time to capture changes in cloud optical properties at the natural timescale of cloud evolution. We compared values of τ retrieved by REDvsNIR to those retrieved from downward shortwave fluxes and from microwave brightness temperatures. The flux method generally underestimates τ relative to the REDvsNIR method. Even for overcast but inhomogeneous clouds, differences between REDvsNIR and the flux method can be as large as 50%. In addition, REDvsNIR agreed to better than 15% with the microwave method for both overcast and broken clouds. The second method, dubbed COUPLED, retrieves τ by combining zenith radiances with fluxes. While extra information from fluxes was expected to improve retrievals, this is not always the case. In general, however, the COUPLED and REDvsNIR methods retrieve τ to within 15% of each other

Building relationships with the invisible in the digital (global) economy (BRIDGE).

Access to products, services and government is increasingly reliant on people being able to use information and communications technologies: from computers to mobile phones. Whilst there are many obvious benefits to those already familiar with the technology, those that do not have the skills or inclination to interact through such technology can get excluded and this may eventually lead to a permanent disadvantage. These groups within society can be very large according to the UK government, with 70% of over 65s reported as never having used the Internet (www.statistics.gov.uk, 2008). As companies grow in scale and design products and services for global rather than local markets it becomes harder to track these partially excluded groups. This is reported as a growing 'psychic distance' between the designers of technologies and the prospective users of those technologies, with a risk that those excluded from the market today will become effectively invisible to designers of future products. Such users' requirements of technology no longer inform the design process and create a digital divide that is socially constructed rather than economically constrained. This is neither good for society nor business, where such exclusion may alienate, as well as prevent business from identifying and engaging with latent demand for their products and services. This project aims to build a 'Bridge' from the needs of technologically excluded users to the capabilities of suppliers of products and services. This will be achieved through exploration of users' expectations, desires and needs and by building design guidelines to help address them. The project will extrapolate the results of this work to wider markets. In order to realise these goals, a combination is needed of qualitative research methods to deliver a detailed picture of user needs, and quantitative methods to map that to the data that large global corporations would typically hold about their current customers and markets. User needs identified through qualitative methods need to be related to behavioural characteristics observed through data analysis and modelling of demand within global markets. This element of the project builds on direct engagement with industry, both with designers, and their existing customers, as well as the organisational processes and data that relate one to the other and informs the designer's view of their users. Through direct engagement with users, designers and producers, BRIDGE will contribute to the design of new products, services and interfaces. As design improves and becomes more socially inclusive, better and more sustainable relationships can be established with consumers. This knowledge can be used to identify opportunities for expansion within global markets for UK industry and hence has the potential to benefit individuals, society and the economy overall

Deep Learning for Vanishing Point Detection Using an Inverse Gnomonic Projection

We present a novel approach for vanishing point detection from uncalibrated monocular images. In contrast to state-of-the-art, we make no a priori assumptions about the observed scene. Our method is based on a convolutional neural network (CNN) which does not use natural images, but a Gaussian sphere representation arising from an inverse gnomonic projection of lines detected in an image. This allows us to rely on synthetic data for training, eliminating the need for labelled images. Our method achieves competitive performance on three horizon estimation benchmark datasets. We further highlight some additional use cases for which our vanishing point detection algorithm can be used.Comment: Accepted for publication at German Conference on Pattern Recognition (GCPR) 2017. This research was supported by German Research Foundation DFG within Priority Research Programme 1894 "Volunteered Geographic Information: Interpretation, Visualisation and Social Computing

Thermal spin transport and spin-orbit interaction in ferromagnetic/non-magnetic metals

In this article we extend the currently established diffusion theory of spin-dependent electrical conduction by including spin-dependent thermoelectricity and thermal transport. Using this theory, we propose new experiments aimed at demonstrating novel effects such as the spin-Peltier effect, the reciprocal of the recently demonstrated thermally driven spin injection, as well as the magnetic heat valve. We use finite-element methods to model specific devices in literature to demonstrate our theory. Spin-orbit effects such as anomalous-Hall, -Nernst, anisotropic magnetoresistance and spin-Hall are also included in this model