3,574 research outputs found
Voice Compression and Communications: Principles and Applications for Fixes and Wireless Channels
No full textUp-to-date, expert coverage of topics in wireless voice communications Voice communication is the most important facet of mobile radio service. Even when the predicted surge of wireless data and Internet services becomes a reality, voice will remain the most natural means of human communication. Voice Compression and Communications details issues in wireless voice communications and treats compression, channel coding, and wireless transmission as a joint subject. Part I covers background material, whereas Part II provides detailed information on both proprietary and standardized analysis-by-synthesis codecs, including the speech codecs of virtually all existing wireline-based and wireless systems. Parts III and IV discuss mainly research-based wideband, audio, as well as very low-rate schemes likely to find their way into future standards. Voice Compression and Communications describes fundamental concepts in a non-mathematical way early in the book for those with only a background knowledge of signal processing and communications. More advanced readers will find detailed discussions of theoretical principles, future concepts, and solutions to various specific wireless voice communications problems
1973-10-25 Morehead State Concert and Lecture Series J.P. Donleavy
No full textRenowned author J.P. Donleavy speaks on the plight of an author and the methods to write, recorded on October 25, 1973
Testing of tungsten coatings in JET for the ITER-like wall
No full textA CFC tile 5 from the JET outer divertor, and CFC tiles from neutral beam shine-through and re-ionisation regions were coated with tungsten and exposed during the 2005-7 JET campaigns in preparation for the ITER-like wall project. Approximately 1.6 microns of coating were eroded from the tile 5 during high-delta discharges when the outer strike-point is on the tile. The coatings on the other tiles were unaffected by NB-heating and divertor discharges, however a tile mounted near the centre of the Inner Wall Guard Limiter lost all its coating from the surface within 10 mm of the tile leading edge; this probably occurred during the ramp-up phase of JET discharges. (C) 2009 J.P. Coad. Published by Elsevier B.V. All rights reserved
Entrainment and detrainment rates from the piv measurements at the top of laboratory analogs of stratocumulus and cumulus clouds
No full textWe analyze mixing at the top of laboratory analogs of convective clouds: stratocumulus and cumulus to investigate entrainment of environmental air into the cloud. We retrieve two components of air velocity using Particle Image Velocimetry technique. Suitable image processing allows to determine cloud–clear air interface. Using velocity differences between cloudy and clear sides of the interface we calculate entrainment / detrainment rates
Vortex Dynamics in The Transitional and Turbulent Wake of 6:1 Prolate Spheroid at 45-deg incidence angle
No full textThe incompressible flow past a 6:1 prolate spheroid with an inclination angle of 45o at Re = 3,000 has been studied by means of direct numerical simulations (DNS). The Reynolds number is based on the inflow velocity and minor-axis length. The preliminary results presented here are focused mainly on vortex dynamics and vortical structures in the wake. The wake behind this configuration starts almost symmetric but is soon strongly deflected and bent as it evolves to the intermediate wake. A pair of unequal-strength vortices dominates the intermediate wake, of which one exhibits the shape of a long vortex tube while the other rapidly breaks down into turbulent-like vortical structures
Experimental characterisation of large scale structures in a high Reynolds number turbulent boundary layer
No full textA very large field of view (4δ x 1δ) with a good spatial resolution owing to the use of four 2k x 2k pixel cameras was conducted in a flat plate boundary layer at two Reynolds numbers (Reθ ≈7,500 and 20,000). Comparing the flow statistics with previously obtained hot-wire data under similar flow conditions show good agreement. The goal of this experiment is to detect and characterise the large scale motions which develop in the log region of a high Reynolds number turbulent boundary layer
Letter from J.P. Bradley to Mr. [William] S. Martin The Dominguez Estate Company, June 28, 1940
No full textRegarding attached payment by Mr. K.L. Schaap settling his account
Optical fibre sensors, past, present and future - a personal view
No full textThe field of optical fibre sensors has been an attractive area of research, ever since the mid 1980s, at a time when optical fibre communications technology had already started to find commercial success. The area was of great academic interest because of the wide variety of direct and indirect interactions with these new optical waveguides, both physical and chemical, which were seen to be possible. Much of the early research, mostly by academics who had previously worked in fibre communications, was highly speculative, and initially found very little commercial application. Even then, however, many confidently believed it to have great future potential. The difficulty at that time was that most existing electrical sensors were relatively cheap, and of course this technology was far more mature, whereas the fibre sensor area lacked many of the simple building blocks necessary for simple, reliable and cost-effective production. Many of the early sensors therefore, quite naturally struggled to find a competitive position. Since then, the many years of research has resulted in an increasing variety of available low-cost optical fibre components becoming available and the research on the sensor technology has lead to many truly useful sensors for what are still niche areas, but ones having real commercial potential. As a result, prospects for wider application are becoming better each year. The paper will start in a tutorial manner, by discussing and classifying the types of optical fibre sensors, discuss the care that has to be taken in their design, and will include a few case studies of some of the very early sensors. It will then go on to describe where several types of sensors have found successful application in the last decade. Finally, the author will discuss the areas where he believes they are likely to find increasing commercial success in future. Please note that the paper will present a personal view of the area, by a research scientist/engineer who has worked in the optical fibre sensors field since 1986, initially as an industrial researcher and later returning as an academic, and who is now active as a freelance consultant in the area
Material migration and fuel retention studies during the JET carbon divertor campaigns
No full textThe first divertor was installed in the JET machine between 1992 and 1994 and was operated with carbon tiles and then beryllium tiles in 1994–5. Post-mortem studies after these first experiments demonstrated that most of the impurities deposited in the divertor originate in the main chamber, and that asymmetric deposition patterns generally favouring the inner divertor region result from drift in the scrape-off layer. A new monolithic divertor structure was installed in 1996 which produced heavy deposition at shadowed areas in the inner divertor corner, which is where the majority of the tritium was trapped by co-deposition during the deuterium-tritium experiment in 1997. Different divertor geometries have been tested since such as the Gas-Box and High-Delta divertors; a principle objective has been to predict plasma behaviour, transport and tritium retention in ITER. Transport modelling experiments were carried out at the end of four campaigns by puffing 13C-labelled methane, and a range of diagnostics such as quartz-microbalance and rotating collectors have been installed to add time resolution to the post-mortem analyses. The study of material migration after D-D and D-T campaigns clearly revealed important consequences of fuel retention in the presence of carbon walls. They gave a strong impulse to make a fundamental change of wall materials. In 2010 the carbon divertor and wall tiles were removed and replaced with tiles with Be or W surfaces for the ITER-Like Wall Project
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