6,712 research outputs found
Twistor Construction of Higher-Dimensional Black Holes - Part II: Examples
We apply the twistor construction for higher-dimensional black holes to known
examples in five space-time dimensions. First the patching matrices are
calculated from the explicit metric for these examples. Then an ansatz is
proposed for obtaining the patching matrix instead from the data of rod
structure and angular momenta. The ansatz is tested on examples with up to
three nuts, and these are shown to give flat space, the Myers-Perry solution
and the black ring, as expected. Rules for the transition between different
adaptations of the patching matrix and for the elimination of conical
singularities are developed and seen to work.Comment: 35 pages, 5 figure
Space reactor/Stirling cycle systems for high power lunar application
An analysis is performed to mathematically model a 550 kWe lunar base power supply which uses a SP-100 reactor coupled with Stirling converters. The reactor is placed in an excavation to keep activated coolant in the hole and to allow maintenance of the components outside the hole. Two technology levels are considered. They are 1050 and 1300 K heater head Stirling converts. It is found that for a 1050 K converter the total mass which provided 1000 volts DC at 250 m is 14,366 kg while the 1300 K system mass is 12,104 kg. The radiation area of the 1050 and 1300 K systems are 641 and 356 sq m respectively. Comparisons are made with Brayton and thermionic systems with both near term and advanced technology considered
Scalar gain interpretation of large order filters
A technique is developed which demonstrates how to interpret a large fully-populated filter gain matrix as a set of scalar gains. The inverse problem is also solved, namely, how to develop a large-order filter gain matrix from a specified set of scalar gains. Examples are given to illustrate the method
Fate of global superconductivity in arrays of long SNS junctions
Normal-metal films overlaid with arrays of superconducting islands undergo
Berezinskii-Kosterlitz-Thouless (BKT) superconducting transitions at a
temperature . We present measurements of T for arrays of
mesoscopic Nb islands patterned on Au films for a range of island spacings .
We show that , and explain this dependence in terms of the
quasiclassical prediction that the Thouless energy, rather than the
superconducting gap, governs the inter-island coupling. We also find two
deviations from the quasiclassical theory: (i) is sensitive to island
height, because the islands are mesoscopic; and (ii) for widely spaced islands
the transition appears to lead, not to a superconducting state, but to a
finite-resistance "metallic" one.Comment: 12 pages, 4 figure
A near real-time algorithm for flood detection in urban and rural areas using high resolution Synthetic Aperture Radar images
A near real-time flood detection algorithm giving a synoptic overview of the extent of flooding in both urban and rural areas, and capable of working during night-time and day-time even if cloud was present, could be a useful tool for operational flood relief management and flood forecasting. The paper describes an automatic algorithm using high resolution Synthetic Aperture Radar (SAR) satellite data that assumes that high resolution topographic height data are available for at least the urban areas of the scene, in order that a SAR simulator may be used to estimate areas of radar shadow and layover. The algorithm proved capable of detecting flooding in rural areas using TerraSAR-X with good accuracy, and in urban areas with reasonable accuracy
Fight-dancing and the festival: Tabuik in Pariaman, Indonesia, and Iemanjá in Salvador da Bahia, Brazil
Festivals bring people together in affirmations of community.
This article looks at two festivals in coastal locations in
Indonesia and Brazil with a close inspection of performances
of fight-dancing included within both festivals. The
improvisatory or choreographed organization of the fight-
dancing performances echoes the manner in which the festivals
themselves are assembled. As these festivals grow in popularity,
the process of inventing tradition is heterogeneously co-
constituted by those parties who actively invest in the symbolic
capital of the events. Verbal and non-verbal forms of expression
reinforce each other in the construction of a multivalent sense of
regional traditions. The corporeal engagement of organisers and
participants blurs the boundary between embodied remembering
and narrative accounts. Based on archival research and
ethnographic fieldwork, this article explores the interweaving
of fight-dancing with the history, growth, and post-colonial expression of regional festivals
Tidal and marine energy in the uk– identifying the future challenges for supply chain development
The purpose of this paper is to investigate the current technical and operational supply chain issues surrounding the development of tidal and marine energy production in the UK. The paper outlines the market and growth potential of tidal energy production in the UK before identifying the key supply chain themes surrounding tidal energy production including an analysis of the portability and transferability of current supply chain thinking and development from other renewable energy systems such as wind turbine technology towards the development of tidal energy supply chain systems. The paper closes by identifying the major challenges that the UK supply chain must overcome in order to develop a comprehensive and robust supply chain system
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