720 research outputs found
In situ UHVEM study of {113}-defect formation in Si nanowires
Results are presented of a study of {113}-defect formation in vertical Si nanowire n-type tunnel field effect transistors with nanowire diameters ranging from 40 to 500 nm. The nanowires are etched into an epitaxial moderately As doped n-type layer grown on a heavily As doped n(+) Si substrate. p(+) contacts on the nanowire are created by epitaxial growth of a heavily B doped layer. Using focused ion beam cutting, samples for irradiation are prepared with different thicknesses so that the nanowires are fully or partially embedded in the sample thickness. {113}-defects are created in situ by 2 MeV e-irradiation in an ultra-high voltage electron microscope between room temperature and 375 degrees C. The observations are discussed in the frame of intrinsic point defect properties, taking into account the role of dopants and capping layers. The important impact of the specimen thickness is elucidated
M31 PAndromeda Cepheid sample observed in four HST bands
Using the M31 PAndromeda Cepheid sample and the HST PHAT data we obtain the
largest Cepheid sample in M31 with HST data in four bands. For our analysis we
consider three samples: A very homogeneous sample of Cepheids based on the
PAndromeda data, the mean magnitude corrected PAndromeda sample and a sample
complementing the PAndromeda sample with Cepheids from literature. The latter
results in the largest catalog with 522 fundamental mode (FM) Cepheids and 102
first overtone (FO) Cepheids with F160W and F110W data and 559 FM Cepheids and
111 FO Cepheids with F814W and F475W data. The obtained dispersion of the
Period-Luminosity relations (PLRs) is very small (e.g. 0.138 mag in the F160W
sample I PLR). We find no broken slope in the PLRs when analyzing our entire
sample, but we do identify a subsample of Cepheids that causes the broken
slope. However, this effect only shows when the number of this Cepheid type
makes up a significant fraction of the total sample. We also analyze the sample
selection effect on the Hubble constant.Comment: 32 pages, 19 figures, 9 tables, accepted for publication in ApJ,
electronic data will be available on CD
Impulsbasierte Dynamiksimulation von Mehrkörpersystemen in der virtuellen Realität
Die dynamische Simulation gewinnt im Bereich der virtuellen Realität immer mehr an Bedeutung. Sie ist ein wichtiges Hilfsmittel, um den Grad der Immersion des Benutzers in eine virtuelle Welt zu erhöhen. In diesem Anwendungsbereich ist die Geschwindigkeit des verwendeten Simulationsverfahrens entscheidend. Weitere Anforderungen an das Verfahren sind unter anderem Genauigkeit, Stabilität und eine einfache Implementierung. In dieser Arbeit wird ein neues impulsbasiertes Verfahren für die dynamische Simulation von Mehrkörpersystemen vorgestellt. Dieses erfüllt, im Gegensatz zu klassischen Verfahren, alle Anforderungen der virtuellen Realität. Das vorgestellte Verfahren arbeitet ausschließlich mit Impulsen, um mechanische Gelenke, Kollisionen und bleibende Kontakte mit Reibung zu simulieren
Dynamiksimulation in der Computergraphik
Die interaktive physikalisch-basierte Simulation von Starrkörpern und deformierbaren Festkörpern ist ein wichtiges und aktuelles Forschungsgebiet in der Computergraphik und ein essentieller Bestandteil in vielen Anwendungen, wie z.B. Virtual Prototyping, Computerspiele oder Trainingssimulatoren. In dieser Arbeit werden interaktive Simulationsmethoden für Mehrkörpersysteme, Textilien und inkompressible deformierbare Volumenkörper vorgestellt
Effects of a wave power park with no-take zone on decapod abundance and size
Past studies have revealed higher levels of biodiversity, total abundance, and size of
individuals around offshore installations of renewable energy. This study investigated the effects
of Lysekil wave power park (area 0.5 km2) on the abundance and carapace size of decapods at the
Swedish west coast. For that purpose, decapods were caught with cages during four consecutive
summers. Two types of cages were applied to catch a wide range of decapod species and sizes. The
abundance and size of decapods were not significantly different within the wave power park and up
to a distance of 360 m outside of it. The catch rate, i.e., number of decapods caught in 24 h, was not
significantly different among sampling locations but revealed inter-annual variation for both cage
types. The results suggest a limited role of the incidental no-take zone of the small Lysekil wave
power park on the abundance and size of local decapods. However, neither were negative impacts,
such as decreasing abundances or smaller carapace sizes, discovered. As an increase in the number
of marine renewable energy production sites is foreseen, a scaled-up and larger study addressing
MPA networks and other environmental interactions should be considered
- …