1,283 research outputs found
Two-Particle Schroedinger Equation Animations of Wavepacket-Wavepacket Scattering (revised)
A simple and explicit technique for the numerical solution of the
two-particle, time-dependent Schr\"{o}dinger equation is assembled and tested.
The technique can handle interparticle potentials that are arbitrary functions
of the coordinates of each particle, arbitrary initial and boundary conditions,
and multi-dimensional equations. Plots and animations are given here and on the
World Wide Web of the scattering of two wavepackets in one dimension.Comment: 13 pages, 8 figures, animations at
http://nacphy.physics.orst.edu/ComPhys/PACKETS
Resonant tunneling through protected quantum dots at phosphorene edges
We theoretically investigate phosphorene zigzag nanorribons as a platform for
constriction engineering. In the presence of a constriction at the upper edge,
quantum confinement of edge protected states reveals resonant tunnelling
Breit-Wigner transmission peaks, if the upper edge is uncoupled to the lower
edge. Coupling between edges in thin constrictions gives rise to Fano-like and
anti-resonances in the transmission spectrum of the system.Comment: 8 pages,7 figure
Controlling Multistability in a Vibro-Impact Capsule System
This is the final version of the article. Available from Springer Verlag via the DOI in this record.This work concerns the control of multistability in a vibro-impact capsule system driven by a harmonic excitation. The capsule is able to move forward and backward in a rectilinear direction, and the main objective of this work is to control such motion in the presence of multiple coexisting periodic solutions. A position feedback controller is employed in this study, and our numerical investigation demonstrates that the proposed control method gives rise to a dynamical scenario with two coexisting solutions, corresponding to forward and backward progression. Therefore, the motion direction of the system can be controlled by suitably perturbing its initial conditions, without altering the system parameters. To study the robustness of this control method, we apply numerical continuation methods in order to identify a region in the parameter space in which the proposed controller can be applied. For this purpose, we employ the MATLAB-based numerical platform COCO, which supports the continuation and bifurcation detection of periodic orbits of non-smooth dynamical systems.The second author has been supported by a Georg Forster Research Fellowship granted by the Alexander von Humboldt Foundation, Germany. The authors would like to thank Dr. Haibo Jiang for stimulating discussions and comments on this work
Controlling coexisting attractors of an impacting system via linear augmentation
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.This paper studies the control of coexisting attractors in an impacting system via a recently developed
control law based on linear augmentation. Special attention is given to two control issues in the framework
of multistable engineering systems, namely, the switching between coexisting attractors without altering
the system’s main parameters and the avoidance of grazing-induced chaotic responses. The effectiveness
of the proposed control scheme is confirmed numerically for the case of a periodically excited, soft impact
oscillator. Our analysis shows how path-following techniques for non-smooth systems can be used in order
to determine the optimal control parameters in terms of energy expenditure due to the control signal and
transient behavior of the control error, which can be applied to a broad range of engineering problemsThe second author has been supported by the ‘DRESDEN Fellowship Programm’ of the TU Dresden
Lucky Spectroscopy, an equivalent technique to Lucky Imaging. Spatially resolved spectroscopy of massive close visual binaries using the William Herschel Telescope
CONTEXT: Many massive stars have nearby companions whose presence hamper
their characterization through spectroscopy. AIMS: We want to obtain spatially
resolved spectroscopy of close massive visual binaries to derive their spectral
types. METHODS: We obtain a large number of short long-slit spectroscopic
exposures of five close binaries under good seeing conditions, select those
with the best characteristics, extract the spectra using multiple-profile
fitting, and combine the results to derive spatially separated spectra.
RESULTS: We demonstrate the usefulness of Lucky Spectroscopy by presenting the
spatially resolved spectra of the components of each system, in two cases with
separations of only ~0.3". Those are delta Ori Aa+Ab (resolved in the optical
for the first time) and sigma Ori AaAb+B (first time ever resolved). We also
spatially resolve 15 Mon AaAb+B, zeta Ori AaAb+B (both previously resolved with
GOSSS, the Galactic O-Star Spectroscopic Survey), and eta Ori AaAb+B, a system
with two spectroscopic B+B binaries and a fifth visual component. The systems
have in common that they are composed of an inner pair of slow rotators orbited
by one or more fast rotators, a characteristic that could have consequences for
the theories of massive star formation.Comment: Accepted for publication in A&A, 7 page
Investigación sobre los motivos por los que los estudiantes universitarios practican deporte. El caso de la Universidad de Granada
A través de este trabajo se pretende conocer cuál es la motivación de los estudiantes de la Universidad de Granada por la actividad física dentro de las actividades deportivas organizadas por dicho organismo. Con este fin, se seleccionó una muestra de 50 jóvenes universitarios que realizan deporte dentro de estasactividades, empleando para ello una escala de opinión tipo Lickert con 6 categorías y 26 motivos hacia los cuales los cuestionados debían mostrar su grado de conformidad. Después del análisis estadístico, secomprobó cómo la categoría mejor puntuada fue la denominada como Forma Física - Salud, restandoimportancia a los aspectos relacionados con las Razones Situacionales y de Autorrealización. A su vez, se determinaron las diferencias en cuanto al sexo por la práctica deportiva en estas actividades organizadas por la Universidad de Granada, comprobando que las chicas valoran más los aspectos socializadores y de práctica en grupo que los chicos.Through this paper, the motivation of Granada University ́s students for the physical activity in the sport program of this organization has tried to be known. With this aim, fifty-five students who are participants in these activities were selected to complete a Lickert ́s Scale with six factors and twenty-six items. Next to statistic analysis, the best factor chosen was "Fitness - Health", taking away importance to the aspects related with "Situacional Reasons" and "Self-realization". At the same time, sexual differences related with physical activity in these activities organized by Granada University were determined, verifying that girls value more the socializators and group practice aspects than boys
Trigonometric parallaxes of young field L dwarfs
(Abridged) We aim to determine the trigonometric parallaxes and proper
motions of a sample of ten field L0-L5 dwarfs with spectroscopic evidence for
low-gravity atmospheres. We obtained J and Ks imaging data using 2-4-m class
telescopes with a typical cadence of one image per month between 2010 January
and 2012 December. We also obtained low resolution optical spectra (R~300,
500-1100 nm) using the 10-m GTCs to assess the presence of lithium absorption
in four targets and confirm their young age. Trigonometric parallaxes and
proper motions were derived to typical accuracies of 1 mas and +/-10 mas/yr.
All ten L dwarfs have large motions, and are located at distances between 9 and
47 pc. They lie above and on the sequence of field dwarfs in the absolute J and
K_s magnitude versus spectral type and luminosity versus Teff diagrams,
implying ages similar to or smaller than those typical of the field. The
detection of atomic lithium in the atmosphere of 2MASS J00452143+1634446 is
reported for the first time. Three dwarfs have locations in the HR diagram
indicative of old ages and high masses consistent with the observed lithium
depletion previously published. We did not find evidence for the presence of
astrometric companions with minimum detectable masses typically >=25 Mjup and
face-on, circular orbits with periods between 60-90 d and 3 yr around eight
targets. The astrometric and spectroscopic data indicate that about 60-70% of
the field L-type dwarfs in our sample with evidence for low-gravity atmospheres
are indeed young-to-intermediate-age brown dwarfs of the solar neighborhood
with expected ages and masses in the intervals 10-500 Myr and 11-45 Mjup. The
peaked-shape of the H-band spectra of L dwarfs, a signpost of youth, appears to
be present up to ages of 120-500 Myr and intermediate-to-high gravities.Comment: Accepted for publication in A&
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