2,311 research outputs found
Non-reciprocal optical reflection from a bidimensional array of subwavelength holes in a metallic film
Using simulations and theoretical arguments we investigate the specular
reflection of a perforated gold film deposited on a glass substrate. A square
lattice of cylindrical holes is assumed to produce the periodic lateral
corrugation needed to hybridize the surface plasmons with radiative states. It
is shown that, contrasting transmission approaches, a knowledge of the
reflection on either side of the film provides separate information on the
gold-vacuum surface plasmons and on the gold-glass interface plasmons. Recent
experimental data on a specific implementation of this system are reexamined;
these show a good agreement between the measured reflections and the
simulations in both directions of incident wave probes. This confirms the
importance of taking into account the reflection asymmetry in the far-field
assessment of surface plasmons properties.Comment: 4 pages, 3 figures. Published versio
Bounded modes to the rescue of optical transmission
This paper presents a brief survey of the evolution of knowledge about
diffraction gratings. After recalling some basic facts, historically and
physically, we introduce the concept of Wood anomalies. Next, we present some
recent works in order to introduce the role of bounded modes in transmission
gratings. The consequences of these recent results are then introduced. This
paper is a secondary publication, published in Europhysics News (EPN 38, 3
(2007) 27-31). In the present version, some additional notes have been added
with related references.Comment: 6 pages, 6 figures. Secondary publication. Brief revie
A Multi-Core Solver for Parity Games
We describe a parallel algorithm for solving parity games,\ud
with applications in, e.g., modal mu-calculus model\ud
checking with arbitrary alternations, and (branching) bisimulation\ud
checking. The algorithm is based on Jurdzinski's Small Progress\ud
Measures. Actually, this is a class of algorithms, depending on\ud
a selection heuristics.\ud
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Our algorithm operates lock-free, and mostly wait-free (except for\ud
infrequent termination detection), and thus allows maximum\ud
parallelism. Additionally, we conserve memory by avoiding storage\ud
of predecessor edges for the parity graph through strictly\ud
forward-looking heuristics.\ud
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We evaluate our multi-core implementation's behaviour on parity games\ud
obtained from mu-calculus model checking problems for a set of\ud
communication protocols, randomly generated problem instances, and\ud
parametric problem instances from the literature.\ud
\u
Bridging the Gap between Enumerative and Symbolic Model Checkers
We present a method to perform symbolic state space generation for languages with existing enumerative state generators. The method is largely independent from the chosen modelling language. We validated this on three different types of languages and tools: state-based languages (PROMELA), action-based process algebras (muCRL, mCRL2), and discrete abstractions of ODEs (Maple).\ud
Only little information about the combinatorial structure of the\ud
underlying model checking problem need to be provided. The key enabling data structure is the "PINS" dependency matrix. Moreover, it can be provided gradually (more precise information yield better results).\ud
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Second, in addition to symbolic reachability, the same PINS matrix contains enough information to enable new optimizations in state space generation (transition caching), again independent from the chosen modelling language. We have also based existing optimizations, like (recursive) state collapsing, on top of PINS and hint at how to support partial order reduction techniques.\ud
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Third, PINS allows interfacing of existing state generators to, e.g., distributed reachability tools. Thus, besides the stated novelties, the method we propose also significantly reduces the complexity of building modular yet still efficient model checking tools.\ud
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Our experiments show that we can match or even outperform existing tools by reusing their own state generators, which we have linked into an implementation of our ideas
Boosting Multi-Core Reachability Performance with Shared Hash Tables
This paper focuses on data structures for multi-core reachability, which is a
key component in model checking algorithms and other verification methods. A
cornerstone of an efficient solution is the storage of visited states. In
related work, static partitioning of the state space was combined with
thread-local storage and resulted in reasonable speedups, but left open whether
improvements are possible. In this paper, we present a scaling solution for
shared state storage which is based on a lockless hash table implementation.
The solution is specifically designed for the cache architecture of modern
CPUs. Because model checking algorithms impose loose requirements on the hash
table operations, their design can be streamlined substantially compared to
related work on lockless hash tables. Still, an implementation of the hash
table presented here has dozens of sensitive performance parameters (bucket
size, cache line size, data layout, probing sequence, etc.). We analyzed their
impact and compared the resulting speedups with related tools. Our
implementation outperforms two state-of-the-art multi-core model checkers (SPIN
and DiVinE) by a substantial margin, while placing fewer constraints on the
load balancing and search algorithms.Comment: preliminary repor
Role of Wood anomalies in optical properties of thin metallic films with a bidimensional array of subwavelength holes
Recents works deal with the optical transmission on arrays of subwavelength
holes in a metallic layer deposited on a dielectric substrate. Making the
system as realistic as possible, we perform simulations to enlighten the
experimental data. This paper proposes an investigation of the optical
properties related to the transmission of such devices. Numerical simulations
give theoretical results in good agreement with experiment and we observe that
the transmission and reflection behaviour correspond to Fano's profile
correlated with resonant response of the eigen modes coupled with
nonhomogeneous diffraction orders. We thus conclude that the transmission
properties observed could conceivably be explained as resulting from resonant
Wood's anomalies.Comment: 7 pages, 10 figures, 2 table
Nanomorphology of the blue iridescent wings of a giant tropical wasp, "Megascolia procer javanensis" (Hymenoptera)
The wings of the giant wasp "Megascolia Procer Javanensis" are opaque and
iridescent. The origin of the blue-green iridescence is studied in detail,
using reflection spectroscopy, scanning electron microscopy and physical
modelling. It is shown that the structure responsible for the iridescence is a
single homogeneous transparent chitin layer covering the whole surface of each
wing. The opacity is essentially due to the presence of melanin in the
stratified medium which forms the mechanical core of the wing.Comment: 8 pages, 7 figures. Improved version. Accepted for publication in
Phys. Rev.
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