5,183 research outputs found
Appendange deployment mechanism for the Hubble Space Telescope program
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
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
Conceptual and mechanical design analyses, and fabrication of noncondensing radiator for environmental testing of space power mercury Rankine syste
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Motion in the north Iceland volcanic rift zone accommodated by bookshelf faulting
Along mid-ocean ridges the extending crust is segmented on length scales of 10–1,000 km. Where rift segments are offset from one another, motion between segments is accommodated by transform faults that are oriented orthogonally to the main rift axis. Where segments overlap, non-transform offsets with a variety of geometries accommodate shear motions. Here we use micro-seismic data to analyse the geometries of faults at two overlapping rift segments exposed on land in north Iceland. Between the rift segments, we identify a series of faults that are aligned sub-parallel to the orientation of the main rift. These faults slip through left-lateral strike-slip motion. Yet, movement between the overlapping rift segments is through right-lateral motion. Together, these motions induce a clockwise rotation of the faults and intervening crustal blocks in a motion that is consistent with a bookshelf-faulting mechanism, named after its resemblance to a tilting row of books on a shelf. The faults probably reactivated existing crustal weaknesses, such as dyke intrusions, that were originally oriented parallel to the main rift and have since rotated about 15° clockwise. Reactivation of pre-existing, rift-parallel weaknesses contrasts with typical mid-ocean ridge transform faults and is an important illustration of a non-transform offset accommodating shear motion between overlapping rift segments.This work was funded by a research grant and studentships from the NERC and Shell.This is the Accepted Version of the article. The final published version is available from the Nature Geoscience website at http://www.nature.com/ngeo/journal/v7/n1/full/ngeo2012.html
Wireless Mesh Networks for Small Satellites Subsystems
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
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
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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The Picatinny Technology Transfer Innovation Center: A business incubator concept adapted to federal laboratory technology transfer
In recent years, the US defense industrial base spawned the aerospace industry, among other successes, and served as the nation`s technology seed bed. However, as the defense industrial base shrinks and public and private resources become scarcer, the merging of the commercial and defense communities becomes necessary to maintain national technological competencies. Cooperative efforts such as technology transfer provide an attractive, cost-effective, well-leveraged alternative to independently funded research and development (R and D). The sharing of knowledge, resources, and innovation among defense contractors and other public sector firms, academia, and other organizations has become exceedingly attractive. Recent legislation involving technology transfer provides for the sharing of federal laboratory resources with the private sector. The Army Research, Development and Engineering Center (ARDEC), Picatinny Arsenal, NJ, a designer of weapons systems, is one of the nation`s major laboratories with this requirement. To achieve its important technology transfer mission, ARDEC reviewed its capabilities, resources, intellectual property, and products with commercial potential. The purpose of the review was to develop a viable plan for effecting a technology transfer cultural change within the ARDEC, Picatinny Arsenal and with the private sector. This report highlights the issues identified, discussed, and resolved prior to the transformation of a temporarily vacant federal building on the Picatinny installation into a business incubator. ARDEC`s discussions and rationale for the decisions and actions that led to the implementation of the Picatinny Technology Transfer Innovation Center are discussed
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