5,183 research outputs found

    Appendange deployment mechanism for the Hubble Space Telescope program

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    The key requirements, a design overview, development testing (qualification levels), and two problems and their solutions resolved during the mechanism development testing phase are presented. The mechanism described herein has demonstrated its capability to deploy/restow two large Hubble Space Telescope deployable appendages in a varying but controlled manner

    Building icelandic igneous crust by repeated melt injections

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    Observations of microseismicity provide a powerful tool for mapping the movement of melt in the crust. Here we record remarkable sequences of earthquakes 20 km below the surface in the normally ductile crust in the vicinity of Askja volcano, in north-east Iceland. The earthquakes occur in swarms consisting of identical waveforms repeating as frequently as every 8 s for up to 3 hours. We use template waveforms from each swarm to detect and locate earthquakes with an automated cross-correlation technique. Events are located in the lower crust and are inferred to be the result of melt being injected into the crust. During melt intrusion high strain rates are produced in conjunction with high pore-fluid pressures from the melt or exsolved carbon dioxide. These cause brittle failure on high angle fault planes located at the tips of sills. Moment tensor solutions show that most of the earthquakes are opening cracks accompanied by volumetric increases. This is consistent with the failure causing the earthquakes by melt injection opening new tensile cracks. Analysis of the magnitude distribution of earthquakes within a swarm reveals a complicated relationship between the imposed strain rates and the fluids that cause brittle failure. The magnitude of the earthquakes is controlled by the distance fluids can migrate along a fault, whereas the frequency of the events is controlled by the strain rate. Faults at the tips of sills act to focus melt transport between sills and so must be an important method of transporting melt through the lower crust.Seismometers were borrowed from the Natural Environment Research Council (NERC) SEIS-UK facility (loans 914 and 968), and the work funded by a research grant from the NERC and by studentship funding for TG from Shell.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/2015JB01200

    Design and fabrication of noncondensing radiator for environmental evaluation of space power mercury Rankine system

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    Conceptual and mechanical design analyses, and fabrication of noncondensing radiator for environmental testing of space power mercury Rankine syste

    Wireless Mesh Networks for Small Satellites Subsystems

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    Wireless mesh networks are a network topology where all the nodes of a system are able to communicate with every other node in the network. This enables an adaptable network that is scalable and has the capability to self-repair and self-configure. The Modular Rapidly Manufactured Small Sat (MRMSS) Project is a small satellite project where we are developing a modular CubeSat architecture. One of the goals of the project is to develop a system that is quick and simple to integrate with a minimal amount of wiring involved. Wireless mesh networks are well suited for this configuration because of the self- configuring and self-repairing aspects of the network. This enables a satellite developer to add subsystem nodes to the network without the need for much hardware re-design. This paper will detail the background of wireless mesh networks, the advantages and limitations of using wireless mesh networks for space applications, and the technical progress of the wireless mesh network development of the MRMSS project

    Diversity, Dilemmas and Transformation in Post-Compulsory Education: an Introduction to the Special Issue on Work Based Research

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    As governments recognize the central place of post-compulsory education in regenerating and modernizing the economic and social fabric of society (BIS 2008), it is appropriate for us as educational researchers to question whether this recognition beckons a different role for research in post-compulsory education. Much of this research is work based, using a broad interpretation of this term, and the majority of articles received by this journal (though the proportion published is a lower one) reflect this balance. Work based research in education poses particular challenges for the researcher and the practitioner, whether the focus is practitioner research, in which case the dilemmas can centre on potential role conflict between practitioner and researcher roles, or whether the work based research is observational – analyzing others’ professional practice, in which case the dilemmas can centre on power relations between researcher and researched, the politics of research, and ethical questions around care for participants and the degree of their involvement or non-involvement in the total research enterprise. This article reviews the prospects for work based research in post-compulsory education and introduces the articles in this special issue

    Slicing Strategies for the Generalised Type-2 Mamdani Fuzzy Inferencing System

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    The final publication is available at Springer via http://dx.doi.org/[insert DOI]".As a three-dimensional object, there are a number of ways of slicing a generalised type-2 fuzzy set. In the context of the Mamdani Fuzzy Inferencing System, this paper concerns three accepted slicing strategies, the vertical slice, the wavy slice, and the horizontal slice or alpha -plane. Two ways of de ning the generalised type-2 fuzzy set, vertical slices and wavy slices, are presented. Fuzzi cation and inferencing is presented in terms of vertical slices. After that, the application of all three slicing strategies to defuzzi cation is described, and their strengths and weaknesses assessed
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