Tradition and creativity : the roots and routes of fiddler Aidan O’Rourke

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Rapid design of LCC current-output resonant converters with reduced electrical stresses

The paper presents and validates a straightforward design methodology for realising LCC current-output resonant converters, with the aim of reducing tank currents, and hence, electrical stresses on resonant components. The scheme is ideally suited for inclusion in a rapid iterative design environment e.g. part of a graphical user interfac

Influence of ROV umbilical on power quality when supplying electrical loads

The paper investigates the effects of a 3 km electrical umbilical cable on power transmission for an "island" supply onboard an all/more electric 'work-class' remote operated vehicle (ROV). It is shown how the chosen transmission voltage and frequency influence efficiency and the selection of power transmission components. A key feature of the paper is a discussion on the use of matrix converters for the propulsion thruster drive system; thereby allowing the input displacement factor to be varied to maintain maximum power transmission efficiency, independent of the thruster power factor. The natural impedance characteristics of the umbilical cable are also considered as means of reducing the input filter requirements for such converter

Prospects of an Astrotourism Site in Namibia

Namibia has significant potential as an astrotourism destination. A handful of sites are already utilizing the region’s clear, dark skies to draw tourists and establish a viable business model. These sites include the Gamsberg Observatory, NamibRand Nature Reserve, Sossusvlei Desert Lodge, Hakos Guest Farm, and Tivoli Astrofarm. The establishment of future professional astronomical research facilities on the Gamsberg Mountain Plateau will also likely add to the attraction of tourists interested in viewing Namibia’s dark skies. The best months for astronomical observing in Namibia are the dry winter months between June and September, which correspond to peak seasonal visits for hunting safaris. Each location of the Jamy Traut Hunting Safari exhibited excellent conditions for viewing. It would be inexpensive for a service like the Jamy Traut Hunting Safari to implement Namibia’s dark skies as an additional service or amenity offered to guests to both draw additional visitors to the sites or enhance their safari experience

Prospects of an Astrotourism Site in Namibia

Namibia has significant potential as an astrotourism destination. A handful of sites are already utilizing the region’s clear, dark skies to draw tourists and establish a viable business model. These sites include the Gamsberg Observatory, NamibRand Nature Reserve, Sossusvlei Desert Lodge, Hakos Guest Farm, and Tivoli Astrofarm. The establishment of future professional astronomical research facilities on the Gamsberg Mountain Plateau will also likely add to the attraction of tourists interested in viewing Namibia’s dark skies. The best months for astronomical observing in Namibia are the dry winter months between June and September, which correspond to peak seasonal visits for hunting safaris. Each location of the Jamy Traut Hunting Safari exhibited excellent conditions for viewing. It would be inexpensive for a service like the Jamy Traut Hunting Safari to implement Namibia’s dark skies as an additional service or amenity offered to guests to both draw additional visitors to the sites or enhance their safari experience

UK open access life cycle

In the centre circle, we have used the 7 stages of the publishing process as described by Neil Jacobs (Jisc), this is followed by institutional processes – of course not all institutions will have all of these processes up and running, e.g. we don’t all have a CRIS. We then included publisher services that directly impact upon the work of the open access team and also Jisc OA services. We then went on to map Jisc OA and above campus services to the life cycle – doing this we immediately found an issue with Publication Router, which is why we have included it twice, once where it currently affects the life cycle and once where we think it should sit – at point of acceptance. Finally, we added the 6 sections of OAWAL showing where we think that fits with the life cycle

A describing function for resonantly commutated H-bridge inverters

Abstract—The paper presents the derivation of a describing function to model the dynamic behavior of a metal oxide semiconductor field effect transistor-based, capacitively commutated H-bridge, including a comprehensive explanation of the various stages in the switching cycle. Expressions to model the resulting input current, are also given. The derived model allows the inverter to be accurately modeled within a control system simulation over a number of utility input voltage cycles, without resorting to computationally intensive switching-cycle level, time-domain SPICE simulations. Experimental measurements from a prototype H-bridge inverter employed in an induction heating application, are used to demonstrate a high degree of prediction accuracy over a large variation of load conditions is possible using the simplified model

Drive systems for operation on deep-sea ROVs

Power systems for thruster actuators and other auxiliaries employed on work-class deep-sea ROVs subject to 300bar ambient pressures, are considered. Emphasis on 3×3 matrix converters for thrusters and 3×2 matrix converters for system auxiliaries, is given, along with experimental results showing operation during pressure cycling consistent with typical operational duties

Sensitivity of Climate Change Projections to Uncertainties in the Estimates of Observed Changes in Deep-Ocean Heat Content

Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/).The MIT 2D climate model is used to make probabilistic projections for changes in global mean surface temperature and for thermosteric sea level rise under a variety of forcing scenarios. The uncertainties in climate sensitivity and rate of heat uptake by the deep ocean are quantified by using the probability distributions derived from observed 20th century temperature changes. The impact on climate change projections of using the smallest and largest estimates of 20th century deep ocean warming is explored. The impact is large in the case of global mean thermosteric sea level rise. In the MIT reference ("business as usual") scenario the median rise by 2100 is 27 and 43 cm in the respective cases. The impact on increases in global mean surface air temperature is more modest, 4.9 C and 3.9 C in the two respective cases, because of the correlation between climate sensitivity and ocean heat uptake required by 20th century surface and upper air temperature changes. The results are also compared with the projections made by the IPCC AR4's multi-model ensemble for several of the SRES scenarios. The multi-model projections are more consistent with the MIT projections based on the largest estimate of ocean warming. However the range for the rate of heat uptake by the ocean suggested by the lowest estimate of ocean warming is more consistent with the range suggested by the 20th century changes in surface and upper air temperatures, combined with expert prior for climate sensitivity.This work was supported in part by the Office of Science (BER), U.S. Dept. of Energy Grant No. DE-FG02-93ER61677, NSF, and by the MIT Joint Program on the Science and Policy of Global Change

Novel battery model of an all-electric personal rapid transit vehicle to determine state-of-health through subspace parameter estimation and a Kalman Estimator

Abstract--The paper describes a real-time adaptive battery model for use in an all-electric Personal Rapid Transit vehicle. Whilst traditionally, circuit-based models for lead-acid batteries centre on the well-known Randles’ model, here the Randles’ model is mapped to an equivalent circuit, demonstrating improved modelling capabilities and more accurate estimates of circuit parameters when used in Subspace parameter estimation techniques. Combined with Kalman Estimator algorithms, these techniques are demonstrated to correctly identify and converge on voltages associated with the battery State-of-Charge, overcoming problems such as SoC drift (incurred by coulomb-counting methods due to over-charging or ambient temperature fluctuations). Online monitoring of the degradation of these estimated parameters allows battery ageing (State-of-Health) to be assessed and, in safety-critical systems, cell failure may be predicted in time to avoid inconvenience to passenger networks. Due to the adaptive nature of the proposed methodology, this system can be implemented over a wide range of operating environments, applications and battery topologies