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Gamerota W.R.,University of Florida | Gamerota W.R.,IBM | Uman M.A.,University of Florida | Hill J.D.,CAPE Technologies | Jordan D.M.,University of Florida
Geophysical Research Letters | Year: 2015

Corona streamers are a critical component of lightning leader step formation and are postulated to produce the very high electric fields at their tips that produce runaway electrons resulting in the observed X-ray bursts associated with leader stepping. Corona emanating from the vicinity of the leader tip between leader steps was analyzed using three sequential high-speed video sequences of dart-stepped leaders in three different triggered lightning flashes during the summers of 2013 and 2014 in northeast Florida. Images were recorded at 648 kiloframes per second (1.16μs exposure time, 380ns dead time) at an altitude of 65m or less. In each image sequence, the leader propagates downward in consecutive frames, with corona streamers observed to fan outward from the bright leader tip in less than the image frame time of about 1.5μs. In 21 exposures, corona streamers propagate, on average, 9m below the bright leader tip. Key Points Corona streamers imaged in three dart-stepped leaders near ground Average streamer length about 9m Side corona duration less than 1.54μs ©2015. American Geophysical Union. All Rights Reserved.

Suttorp M.J.,St. Antonius Hospital | Stella P.R.,University Utrecht | Dens J.,Hospital Oost Limburg | McKenzie J.M.,DISAVascular | And 2 more authors.
Netherlands Heart Journal | Year: 2015

Aim To report clinical follow-up at 6 months after implantation of the ultra-thin strut cobalt chromiumSolarFlex stent in a real-world setting. Methods and results Patients (n=240) with single or multiple vessel coronary artery disease undergoing percutaneous coronary intervention (PCI) at four sites in Europe were enrolled in the SOLSTICE (SolarFlex Stent in Routine Clinical Practice) registry. Follow-up at 6 months was 100%. Diabetes was present in 29% of the patients, 30% presented with acute myocardial infarction and 17% had unstable angina. Of the patients, 27% had previously undergone PCI or coronary artery bypass surgery. Lesion complexity was high (50% B2+C type lesions). Device success was achieved in 99.7% of cases and themajor adverse cardiac event (MACE) ratewas 5.8% at 6 months of follow-up. Target lesion revascularisation (TLR) was 5.0% at 6 months. Conclusions The SOLSTICE registry showed that in a complex real-world setting the SolarFlex bare metal stent, with ultra-thin struts and customised scaffolding, provided low clinical MACE and TLR rates. These results provide support for the use of the latest generation bare metal stent in contemporary European practice. © The Author(s) 2014.

Stanford B.K.,NASA | Jutte C.V.,CAPE Technologies | Chauncey Wu K.,NASA
Composite Structures | Year: 2014

The use of tow steered composites, where fibers follow prescribed curvilinear paths within a laminate, can improve upon existing capabilities related to aeroelastic tailoring of wing structures, though this tailoring method has received relatively little attention in the literature. This paper demonstrates the technique for a cantilevered flat plate in low-speed flow. A genetic algorithm is used to locate the Pareto front between static aeroelastic stresses and dynamic flutter boundaries. The impact of various tailoring choices upon the aeroelastic performance is quantified: curvilinear fiber steering versus straight fiber steering and certifiable versus non-certifiable stacking sequences. © Published by Elsevier Ltd.

Nesbitt A.B.,CAPE Technologies
Minerals Engineering | Year: 2010

Two case studies are presented in which a continuous loss of capacity in two samples of acid resin, are observed over 900 cycles of loading and regeneration. By completing the batch kinetic testing of the resin at different turbulences and calculating the intra-particle diffusion rates of the counter and co-ion, the effect of turbulence on the independence/dependence of the intra-particle diffusion could be established. A systematic loss in capacity and change in kinetics is reported in both case studies and it is postulated that the reason for this is the loss of active sites within the resin matrix. The significance of this observation is that standard tests done for a new resin application could significantly overestimate the commercial performance of the resin concerned. This paper proposes a method in which resin might be studied prior to inclusion in a particular process, with the objective of determining its effective life span. © 2009.

Dunning P.D.,National Institute of Aerospace | Stanford B.K.,NASA | Kim H.A.,University of Bath | Jutte C.V.,CAPE Technologies
Journal of Fluids and Structures | Year: 2014

A functionally graded material (FGM) provides a spatial blend of material properties throughout a structure. This paper studies the efficacy of FGM for the aeroelastic tailoring of a metallic cantilever plate-like wing, wherein a genetic algorithm provides Pareto trade-off curves between static and dynamic aeroelastic metrics. A key comparison is between the effectiveness of material grading, geometric grading (i.e. plate thickness variations), and using both simultaneously. The introduction of material grading does, in some cases, improve the aeroelastic performance. This improvement, and the physical mechanism upon which it is based, depends on numerous factors: the two sets of metallic material parameters used for grading; the sweep of the plate; the aspect ratio of the plate; and whether the material is graded continuously or discretely. © 2014 Elsevier Ltd.

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