272 research outputs found
Non-rigid image registration to reduce beam-induced blurring of cryo-electron microscopy images
No full textMicroscopic imaging and technolog
Traffic monitoring using helicopters; a system for the acquisition and analysis of image sequences to model longitudinal driving behavior
No full textAerospace Engineerin
Sequential and Automatic Image-Sequence Registration of Road Areas Monitored from a Hovering Helicopter
No full textIn this paper, we propose an automatic and sequential method for the registration of an image sequence of a road area without ignoring scene-induced motion. This method contributes to a larger work, aiming at vehicle tracking. A typical image sequence is recorded from a helicopter hovering above the freeway. The demand for automation is inevitable due to the large number of images and continuous changes in the traffic situation and weather conditions. A framework is designed and implemented for this purpose. The registration errors are removed in a sequential way based on two homography assumptions. First, an approximate registration is obtained, which is efficiently refined in a second step, using a restricted search area. The results of the stabilization framework are demonstrated on an image sequence consisting of 1500 images and show that our method allows a registration between arbitrary images in the sequence with a geometric error of zero in pixel accuracy
Corrigendum to: Lattice dynamics in the conformational environment of multilayered hexagonal boron nitride (h-BN) results in peculiar infrared optical responses
No full textDifferently from what is reported in a published version of the paper (Phys. Chem. Chem. Phys., 2021, 23, 7247-7260), F.K. is not considered corresponding author of: 'Lattice dynamics in the conformational environment of multilayered hexagonal boron nitride (h-BN) results in peculiar infrared optical responses'. The relevant correspondence should be addressed to L.C. The authorship of F.K. is recognized to be honorary.</p
Reliability Analysis of an Ultrasonic Guided Wave Based Structural Health Monitoring System for a Carbon Fibre Reinforced Thermoplastic Torsion-box
No full textCertification is the key step towards the implementation of structural health monitoring (SHM) as part of condition based maintenance programmes of aircraft fleets. That can only be accomplished by demonstration of system performance in multiple scenarios and in a statistically relevant way. This paper describes a fully computational approach for reliability assessment of an ultrasonic guided wave (GW) based SHM system for a full-scale stiffened panel of a horizontal stabilizer torsion-box entirely made of carbon fibre reinforced thermoplastic. A pseudo-stochastic nature is attributed to the damage index values calculated from the finite-element signals, allowing hit-miss data to be generated. That data is in turn employed for the computation of probability of detection curves and relative operating characteristics. The results of this research show that detailed damage diagnostics in full-scale complex composite structures can be achieved by using ultrasonic GWs under the hotspot monitoring philosophy. Moreover, it is demonstrated that properly validated models of the monitoring environment can be used for reliability analysis of GW based SHM systems for full-scale complex composite structures, thereby reducing the need for extensive and costly experimental test campaigns, which in turn can contribute to an acceleration of the establishment of a certification framework for SHM systems.Structural Integrity & CompositesAerospace Structures & Material
Toestandsvergelijkingen voor polymeren
No full textVoor vloeistoffen -zowel monomere als polymere- is het opstellen van een theorie die nauwkeurige resultaten geeft voor onder andere de toestandsvergelijking (p,V,T-vergelijking) een nog groter probleem dan voor vaste stoffen (kristallijn) of gassen (ver boven het kritisch punt). Enerzijds heeft men te maken met een systeem dat ongeordend is en anderzijds een hoge dichtheid heeft, waardoor men het "veel deeltjes probleem" principieel niet kan benaderen door alleen paar-interacties te beschouwen. Pogingen om een zo exact mogelijke theorie op te stellen hebben doorgaans als resultaat een zeer ingewikkelde toestandsvergelijking, terwijl juist goede hanteerbaarheid een wenselijke eigenschap is. In deze scriptie zal onder andere een overzicht worden gegeven van in de literatuur voorgestelde toestandsvergelijkingen voor polymeren. Zij vallen globaal uiteen in drie groepen: l) toestandsvergelijkingen oorspronkelijk opgesteld voor monomere vloeistoffen, die direct worden toegepast op polymeren of modificaties van deze modellen voor polymeren; 2) theorieen die direct uitgaan van ketenmolekulen en 3) een aantal zuiver empirische relaties.Applied Science
Analogie-model ter bestudering van knikverschijnselen in het elasto-plastische gebied
No full textCivil Engineering and Geoscience
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