2,291 research outputs found
A combinatorial approach to metamaterials discovery
Some fifteen years ago a paper reporting a combinatorial approach to materials discoveries revolutionized materials research and other disciplines such as chemistry and pharmacology [1]. Here we report on how a combinatorial approach combined with advanced nanofabrication helps to discover photonic metamaterials optimized for prescribed functionalities
A combinatorial approach to metamaterials discovery
We report a high throughput combinatorial approach to photonic metamaterial optimization. The new approach is based on parallel synthesis and subsequent optical characterization of large numbers of spatially addressable nanofabricated metamaterial samples (libraries) with quasi-continuous variation of design parameters under real manufacturing conditions. We illustrate this method for Fano-resonance plasmonic nanostructures, arriving at explicit recipes for high quality factors needed for switching and sensing applications
A new type of optical activity in a toroidal metamaterial
We demonstrate experimentally and numerically the first ever observation of optical activity in a chiral metamaterial that is underpinned by the exotic resonant combination of an electric quadrupole and the elusive toroidal dipole
Orientations, lattice polytopes, and group arrangements II: Modular and integral flow Polynomials of graphs
We study modular and integral flow polynomials of graphs by means of subgroup arrangements and lattice polytopes. We introduce an Eulerian equivalence relation on orientations, flow arrangements, and flow polytopes; and we apply the theory of Ehrhart polynomials to obtain properties of modular and integral flow polynomials. The emphasis is on the geometrical treatment through subgroup arrangements and Ehrhart polynomials. Such viewpoint leads to a reciprocity law on the modular flow polynomial, which gives rise to an interpretation on the values of the modular flow polynomial at negative integers and answers a question by Beck and Zaslavsky.Regal Entertainment Group (Competitive Earmarked Research Grants 600703)Regal Entertainment Group (Competitive Earmarked Research Grants 600506)Regal Entertainment Group (Competitive Earmarked Research Grants 600608
Three-dimensional conceptual model for service-oriented simulation
In this letter, we propose a novel three-dimensional conceptual model for an
emerging service-oriented simulation paradigm. The model can be used as a
guideline or an analytic means to find the potential and possible future
directions of the current simulation frameworks. In particular, the model
inspects the crossover between the disciplines of modeling and simulation,
service-orientation, and software/systems engineering. Finally, two specific
simulation frameworks are studied as examples.Comment: 7 pages, 1 figures, 3 table, Journal of Zhejiang University SCIENCE
A, 2009, 10(8): 1075-108
Quasinormal modes and hidden conformal symmetry in the Reissner-Nordstrom black hole
It is shown that the scalar wave equation in the near-horizon limit respects
a hidden SL(2,R) invariance in the Reissner-Nordstrom (RN) black hole
spacetimes. We use the SL(2,R) symmetry to determine algebraically the purely
imaginary quasinormal frequencies of the RN black hole. We confirm that these
are exactly quasinormal modes of scalar perturbation around the near-extremal
black hole.Comment: 17 pages, 1 figure, version to appear in EPJ
Toroidal circular dichroism
We demonstrate that the induced toroidal dipole, represented by currents flowing on the surface of a torus, makes a distinct and indispensable contribution to circular dichroism. We show that toroidal circular dichroism supplements the well-known mechanism involving electric dipole and magnetic dipole transitions. We illustrate this with rigorous analysis of the experimentally measured, polarization-sensitive transmission spectra of an artificial metamaterial, constructed from elements of toroidal symmetry. We argue that toroidal circular dichroism shall be found in large biomolecules with elements of toroidal symmetry and should be taken into account in the interpretation of circular dichroism spectra of organics
Tunable plasmonic luminescence in reconfigurable metamaterials
We show that new intense luminescence lines associated with transitions from collective plasmonic states below the Fermi level can be artificially created by metamaterial nanostructuring of plasmonic metals and tuned by nanoscale reconfiguration of metamaterial. We report on the experimental demonstration of a new radiation phenomenon on the nanoscale and its engineering into a reconfigurable metadevice: luminescence emission lines within the Fermi sea can be created by nanopatterning metal surfaces and controlled by external electrical inputs. Luminescence emission lines are associated with the decay of plasmonic excitation and are spectrally linked to the plasmonic absorption lines. Wavelength, polarization and intensity of metallic luminescence can be flexibly and independently adjusted by tweaking the geometric parameters of the metamaterial design similar to the way nanostructuring helps engineering semiconductor multiple quantum well and quantum dot luminescence
On the construction of the solution of an equation describing an axially moving string
A Parametric Study of Erupting Flux Rope Rotation. Modeling the "Cartwheel CME" on 9 April 2008
The rotation of erupting filaments in the solar corona is addressed through a
parametric simulation study of unstable, rotating flux ropes in bipolar
force-free initial equilibrium. The Lorentz force due to the external shear
field component and the relaxation of tension in the twisted field are the
major contributors to the rotation in this model, while reconnection with the
ambient field is of minor importance. Both major mechanisms writhe the flux
rope axis, converting part of the initial twist helicity, and produce rotation
profiles which, to a large part, are very similar in a range of shear-twist
combinations. A difference lies in the tendency of twist-driven rotation to
saturate at lower heights than shear-driven rotation. For parameters
characteristic of the source regions of erupting filaments and coronal mass
ejections, the shear field is found to be the dominant origin of rotations in
the corona and to be required if the rotation reaches angles of order 90
degrees and higher; it dominates even if the twist exceeds the threshold of the
helical kink instability. The contributions by shear and twist to the total
rotation can be disentangled in the analysis of observations if the rotation
and rise profiles are simultaneously compared with model calculations. The
resulting twist estimate allows one to judge whether the helical kink
instability occurred. This is demonstrated for the erupting prominence in the
"Cartwheel CME" on 9 April 2008, which has shown a rotation of \approx 115
degrees up to a height of 1.5 R_sun above the photosphere. Out of a range of
initial equilibria which include strongly kink-unstable (twist Phi=5pi), weakly
kink-unstable (Phi=3.5pi), and kink-stable (Phi=2.5pi) configurations, only the
evolution of the weakly kink-unstable flux rope matches the observations in
their entirety.Comment: Solar Physics, submitte
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