1,690 research outputs found
The experience and limitations of using manganese alkaline primary cells in a large operational AUV
No full textThe authors describe how the use of manganese alkaline batteries for the Autosub science programme has enabled the project to progress swiftly from being a technological demonstrator to providing new ways of gathering environmental data not possible by other methods. Throughout the programme, all areas of the battery system have undergone development. that is: specification, design and manufacture of the pack; inspection and testing; packaging, storage and physical handling; electrical and thermal insulation; estimates of remaining endurance; and disposal of depleted packs
Toponymical lexics in the pre-war period of A.T. Tvardovskiy’s creative work
No full textThe pre-war period (1926-1940) of A.T. Tvaedovskiy’s creative work, the great poet of the 20yh century, born in the Smolensk Region, is a period of his rising as an insuperable master of word, a people’s tribune, the time when the main traits of his poetry were developed and when his formation as a founder of the Smolensk Poetic School occurred. One of the central themes of the SPS poets, and first of all, A.T. Tvardovskiy himself, was the theme of “the minor” and “the big”. Motherland, which was materialized in significant motives through a system of toponyms. i.e. the names of geograpphical places. The article analyzes a system of macro- and mictrotoponyms and demonstrates their part in revealing of the thematical content of numerous pre-war poems (A Trip to Zagorye, 1939, Station Pochinok, 1936, and others), as well the first epical poem of the author Strana Muraviya (1936)
Efficient implementation of the domain-integrated field relations method for quasi-static magnetic fields
No full textAuthor accepted manuscript of the 17th Annual Review of Progress in Applied Computational Electromagnetics, Monterey, pp. 337-344, 19 Mar 2001 → 23 Mar 2001Electrical Engineering, Mathematics and Computer Scienc
Exploring beneath the PIG Ice Shelf with the Autosub3 AUV
No full textOn 31st January 2009, two numbers: “range and
bearing” flashing up on a laptop screen, indicated that Autosub3
had returned from its last mission beneath the Pine Island Glacier
(PIG) Ice Shelf in the Western Antarctic. The Autosub technical
team from NOCS, Southampton, onboard the US ice breaker
Nathanial B Palmer breathed a collective sigh of relief. Any
significant technical failure would have resulted in total loss of the
multi million Euro Autonomous Underwater Vehicle with no hope
of recovery from 60 km into the ice shelf cavity. This was the last
of six successful missions to investigate the shape the ice shelf, the
sea bed bathymetry, the currents and the physical oceanography
within the ice cavity. Each are vital to understanding the
interaction between the sea water and the ice shelf, and
quantifying whether the melting rate is changing. During the
cruise, Autosub3 had run beneath the ice for almost 4 days and
for 510 km.
Autosub3 had been exploring the Pine Island Glacier, a floating
extension of the West Antarctic ice sheet, as part of an
international team effort lead by Dr Adrian Jenkins of the British
Antarctic Survey and Dr Stanley Jacobs of the Lamont-Doherty
Earth Observatory, New York. Autosub3 was launched from the
Nathaniel B Palmer, an American icebreaker, as part of the two
month cruise to investigate the oceanography, biology and
glaciology of the Southern Amundsen Sea.
This paper will concentrate on the technical aspects of the
Autosub3 vehicle and its missions under the PIG, and seek to
answer a number of questions: How did the AUV successfully
dead reckon navigate for over 24 hours, and return accurately to
the rendezvous point? How did we cope with the possibility of ice
bergs or sea ice drifting over the recovery position ? How did
Autosub3 (almost always) avoid collision with the jagged ice shelf
above, or the unknown depths of the seabed? How did we
communicate with the vehicle at the start and the end of missions?
How did we manage risk, and prior to the cruise, what
modifications and testing did we apply to the AUV to improve the
overall reliability? What measures did we take during the cruise
to further improve our chances of a successful outcome ?
The paper will outline the history of the use of AUVs for polar
science. Results from the recent cruise will be presented showing
the actual mission tracks, with the echo sounder isonified ice draft
and seabed. Not all went completely to plan: the paper will also
describe the events of Autosub’s close scrape on its 4th mission
under the PIG.
This work was fun
Kinetics of epoxy-asphalt oxidation
No full textIn-depth understanding of the temperature effect on oxidative aging in epoxy-asphalt blends is needed to enable accurate predictions on material response through their service life. Details of the significance of developing prediction models and tools on oxidative aging of pavement materials are presented in a companion paper (Apostolidis et al., Oxidation Simulation of Thin Bitumen Film. AM3P). In this research, the chemical compositional changes of epoxy modified asphalt binders, with and without filler, were analysed after oven-conditioning by means of Fourier transform infrared (FTIR) spectroscopy. With the carbonyl and sulfoxide compounds as aging indices, the sensitivity of chemical compositional changes of bituminous and epoxy-based systems due to the applied temperatures was observed.Accepted Author ManuscriptPavement Engineerin
Constraint Propagation and Reverse Multi-Agent Learning
No full textThe development of multi-agent reinforcement learning has been largely driven by the question of how to design learning algorithms to reach some particular notion of optimality of strategies, e.g. Nash equilibria. The set of optimal strategies is not known before the execution of the learning algorithm,however we can often immediately identify a set of clearly undesirable outcomes. Therefore, we propose to consider a dual problem: given a collection of agent algorithms and a collection of unwanted strategy profiles, can one identify a setof starting strategies that invariably lead there? This leads us to study the algorithmic problem of backpropagation of con-straints defining the forbidden region by learning dynamics,through the lens of set-valued maps and interval arithmetics.Accepted author manuscriptInteractive Intelligenc
Signal Integrity in Pulse-train Excited Array Antennas in Time and Space - A Full TD Analysis
No full textSignal integrity in the far-field radiation from pulse-train excited array antennas is studied via full timedomain instruments. The disturbance in the received signal is related to the fidelity factor. At any point in our analysis, the disturbance is evaluated based on a reduced, well defined set of parameters: pulse parameters and pulse repetition rate – temporal dependence, and elementary radiator location – spatial dependence. Their effect is examined by means of illustrative numerical experiments. These results are expedient for enhancing the detectability of the signals radiated by pulse-train excited array antennas, as needed in wireless digital transfer.Accepted author manuscriptEEMS - GeneralTera-Hertz Sensin
Wavefields and reciprocity: Proceedings of a symposium held in honour of Professor dr. A.T. de Hoop, November 20-21, 1996, Delft, the Netherlands
No full textElectrical Engineering, Mathematics and Computer Scienc
A time-domain finite-element method for the computation of three-dimensional acoustic wave fields in inhomogeneous fluids and solids
No full textElectrical Engineering, Mathematics and Computer Scienc
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