23,790 research outputs found
A planar magneto-inductive lens for three-dimensional subwavelength imaging
A planar near-field magnetoinductive lens operating in the microwave range is
presented. The proposed device consists of two parallel planar arrays of
metallic broadside coupled (BC-) split ring resonators (SRRs), or BC-SRRs.
Power coming from a point-like source located in front of the lens is focused
into a receiver located in free space behind the device. This focus is clearly
removed from the back side of the lens, and has a size which is an order of
magnitude smaller than the free space wavelength of the incoming radiation. The
imaging properties of the device mainly relies on the excitation of
magnetoinductive surface waves on the BC-SRR arrays. By simply scaling the
BC-SRRs size, as well as the arrays periodicity, the frequency of operation of
the device can be tuned over a wide frequency range. Thus the proposed design
is potentially useful for many applications ranging from megahertzs to
terahertzs.Comment: 14 pages, 3 figures, submitted to Applied Physics Letter
Otolith morphology of Nezumia sclerorhynchus and Nezumia aequalis (Macrouridae): a useful tool to species identification and ecological studies
Bol. Mus. Mun. Funchal, Sup. N.º 6: 205-212, 2001Otoliths of Nezumia sclerorhynchus and N. aequalis are described and compared. When studying the marine trophic relationships, its general shape and morphometry allows one to separated these two sympatric species.São descritos e comparados os otólitos sagitta de Nezumia sclerorhynchus e de N. aequalis. No estudo das relações tróficas marinhas a sua forma e morfometria permitem distinguir qual destas duas espécies simpátricas foi predada
Heuristic Backtracking Algorithms for SAT
In recent years backtrack search SAT solvers have been the subject of dramatic improvements. These improvements allowed SAT solvers to successfully replace BDDs in many areas of formal verification, and also motivated the development of many new challenging problem instances, many of which too hard for the current generation of SAT solvers. As a result, further improvements to SAT technology are expected to have key consequences in formal verification. The objective of this paper is to propose heuristic approaches to the backtrack step of backtrack search SAT solvers, with the goal of increasing the ability of the SAT solver to search different parts of the search space. The proposed heuristics to the backtrack step are inspired by the heuristics proposed in recent years for the branching step of SAT solvers, namely VSIDS and some of its improvements. The preliminary experimental results are promising, and motivate the integration of heuristic backtracking in state-of-the-art SAT solvers. 1
Effective Lower Bounding Techniques for Pseudo-Boolean Optimization
Linear Pseudo-Boolean Optimization (PBO) is a widely used modeling framework in Electronic Design Automation (EDA). Due to significant advances in Boolean Satisfiability (SAT), new algorithms for PBO have emerged, which are effective on highly constrained instances. However, these algorithms fail to handle effectively the information provided by the cost function of PBO. This paper addresses the integration of lower bound estimation methods with SAT-related techniques in PBO solvers. Moreover, the paper shows that the utilization of lower bound estimates can dramatically improve the overall performance of PBO solvers for most existing benchmarks from EDA. 1
Hawking radiation for non asymptotically flat dilatonic black holes using gravitational anomaly
The -dimensional scalar field action may be reduced, in the background
geometry of a black hole, to a 2-dimensional effective action. In the near
horizon region, it appears a gravitational anomaly: the energy-momentum tensor
of the scalar field is not conserved anymore. This anomaly is removed by
introducing a term related to the Hawking temperature of the black hole. Even
if the temperature term introduced is not covariant, a gauge transformation may
restore the covariance. We apply this method to compute the temperature of the
black hole of the dilatonic non asymptotically flat black holes. We compare the
results with those obtained through other methods.Comment: Latex file, 22 pages. Some discussions enlarged. New references.
Accepted for publication in the European Physical Journal
On Computing Minimum Unsatisfiable Cores
Certifying the correctness of a SAT solver is straightforward for satisfiable instances of SAT. Given
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