Development of a novel, cost-effective, and highly efficient mid-infrared light source has been identified as a major scientific and technological goal within the area of optical gas sensing. We have proposed and investigated a mid-infrared metamaterial thermal emitter based on micro-structured chromium thin film. The results demonstrate that the proposed thermal light source supports broadband and wide angular absorption of both TE- and TM-polarized light, giving rise to broadband thermal radiation with averaged emissivity of ∼0.94 in a mid-infrared atmospheric window of 8-14 μm. The proposed microphotonic concept provides a promising alternative mid-infrared source and paves the way towards novel optical gas sensing platforms for many applications.
Coatings or films are applied to a substrate for several applications, such as waterproofing, corrosion resistance, adhesion performance, cosmetic effects, and optical coatings. When applying a coating to a substrate, it is vital to monitor the coating thickness during the coating process to achieve a product to the desired specification via real time production control. There are several different coating thickness measurement methods that can be used, either in-line or off-line, which can determine the coating thickness relative to the material of the coating and the substrate. In-line coating thickness measurement methods are often very difficult to design and implement due to the nature of the harsh environmental conditions of typical production processes and the speed at which the process is run. This paper addresses the current and novel coating thickness methodologies for application to chromium coatings on a ferro-magnetic steel substrate with their advantages and limitations regarding in-line measurement. The most common in-line coating thickness measurement method utilized within the steel packaging industry is the X-ray Fluorescence (XRF) method, but these systems can become costly when implemented for a wide packaging product and pose health and safety concerns due to its ionizing radiation. As technology advances, nanometer-scale coatings are becoming more common, and here three methods are highlighted, which have been used extensively in other industries (with several variants in their design) which can potentially measure coatings of nanometer thickness in a production line, precisely, safely, and do so in a non-contact and non-destructive manner. These methods are optical reflectometry, ellipsometry and interferometry.
This paper reports on a preliminary study using EutelSat Hotbird 13A (previously known as Hot Bird 6) beacon data at 19.7 GHz and 29.5 GHz (scaled frequency) to evaluate the performance of the 2 nd Generation of Digital Video Broadcasting via Satellite (DVB-S2) on an experimental Ka-band (26-40 GHz) satellite link in the UK. Longterm statistics of rain and atmospheric attenuation were derived from a period of one year's measurements made in Pontypridd, South Wales and in Chilbolton, England, at 19.7 GHz. This is supplemented by meteorological measurements at both sites, and multi-frequency radiometer measurements at Chilbolton. A hypothetical Ka-band satellite broadcast link between Pontypridd and Chilbolton has been designed using the DVB-S2 technology, where the system is configured to use 29.5 GHz as the uplink frequency while 19.7 GHz is used as the downlink frequency. The downlink attenuation time series is based entirely on measured data, whereas the synthetic uplink attenuation time series were a sum of 1 Research Student, School of Engineering, leshan.uggalla@southwales.ac.uk, Not a Member 2 Head of Chilbolton Observatory, Rutherford Appleton Lab., jon.eastment@stfc.ac.uk, Not a Member 3 Professor, School of Engineering, ifiok.otung@southwales.ac.uk, Not a Member Downloaded by KUNGLIGA TEKNISKA HOGSKOLEN KTH on August 7, 2015 | http://arc.aiaa.org | International Communications Satellite Systems Conferences (ICSSC)the computed and scaled attenuation from the measurements at 19.7 GHz. The observed link availability, modulation scheme usage and data throughput in the Ka-band region are calculated and presented. The paper discusses these findings in detail for different satellite link designs, and determines the effectiveness of the various link designs in terms of their availability and data throughput. According to the findings of link outages, a new method has been proposed in order to increase the link availability by integrating Time Diversity (TD) and Maximal Ratio Combining (MRC) into the existing DVB-S2 standard. The integration of TD and MRC into DVB-S2 provides the potential to continue delivering services at below the currentlyrecommended lowest acceptable carrier-to-noise (C/N) threshold in the event of severe weather conditions.
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