15,998 research outputs found

    Tunable Double Negative Band Structure from Non-Magnetic Coated Rods

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    A system of periodic poly-disperse coated nano-rods is considered. Both the coated nano-rods and host material are non-magnetic. The exterior nano-coating has a frequency dependent dielectric constant and the rod has a high dielectric constant. A negative effective magnetic permeability is generated near the Mie resonances of the rods while the coating generates a negative permittivity through a field resonance controlled by the plasma frequency of the coating and the geometry of the crystal. The explicit band structure for the system is calculated in the sub-wavelength limit. Tunable pass bands exhibiting negative group velocity are generated and correspond to simultaneously negative effective dielectric permittivity and magnetic permeability. These can be explicitly controlled by adjusting the distance between rods, the coating thickness, and rod diameters

    Heuristic algorithms for the min-max edge 2-coloring problem

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    In multi-channel Wireless Mesh Networks (WMN), each node is able to use multiple non-overlapping frequency channels. Raniwala et al. (MC2R 2004, INFOCOM 2005) propose and study several such architectures in which a computer can have multiple network interface cards. These architectures are modeled as a graph problem named \emph{maximum edge qq-coloring} and studied in several papers by Feng et. al (TAMC 2007), Adamaszek and Popa (ISAAC 2010, JDA 2016). Later on Larjomaa and Popa (IWOCA 2014, JGAA 2015) define and study an alternative variant, named the \emph{min-max edge qq-coloring}. The above mentioned graph problems, namely the maximum edge qq-coloring and the min-max edge qq-coloring are studied mainly from the theoretical perspective. In this paper, we study the min-max edge 2-coloring problem from a practical perspective. More precisely, we introduce, implement and test four heuristic approximation algorithms for the min-max edge 22-coloring problem. These algorithms are based on a \emph{Breadth First Search} (BFS)-based heuristic and on \emph{local search} methods like basic \emph{hill climbing}, \emph{simulated annealing} and \emph{tabu search} techniques, respectively. Although several algorithms for particular graph classes were proposed by Larjomaa and Popa (e.g., trees, planar graphs, cliques, bi-cliques, hypergraphs), we design the first algorithms for general graphs. We study and compare the running data for all algorithms on Unit Disk Graphs, as well as some graphs from the DIMACS vertex coloring benchmark dataset.Comment: This is a post-peer-review, pre-copyedit version of an article published in International Computing and Combinatorics Conference (COCOON'18). The final authenticated version is available online at: http://www.doi.org/10.1007/978-3-319-94776-1_5

    High rate locally-correctable and locally-testable codes with sub-polynomial query complexity

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    In this work, we construct the first locally-correctable codes (LCCs), and locally-testable codes (LTCs) with constant rate, constant relative distance, and sub-polynomial query complexity. Specifically, we show that there exist binary LCCs and LTCs with block length nn, constant rate (which can even be taken arbitrarily close to 1), constant relative distance, and query complexity exp(O~(logn))\exp(\tilde{O}(\sqrt{\log n})). Previously such codes were known to exist only with Ω(nβ)\Omega(n^{\beta}) query complexity (for constant β>0\beta > 0), and there were several, quite different, constructions known. Our codes are based on a general distance-amplification method of Alon and Luby~\cite{AL96_codes}. We show that this method interacts well with local correctors and testers, and obtain our main results by applying it to suitably constructed LCCs and LTCs in the non-standard regime of \emph{sub-constant relative distance}. Along the way, we also construct LCCs and LTCs over large alphabets, with the same query complexity exp(O~(logn))\exp(\tilde{O}(\sqrt{\log n})), which additionally have the property of approaching the Singleton bound: they have almost the best-possible relationship between their rate and distance. This has the surprising consequence that asking for a large alphabet error-correcting code to further be an LCC or LTC with exp(O~(logn))\exp(\tilde{O}(\sqrt{\log n})) query complexity does not require any sacrifice in terms of rate and distance! Such a result was previously not known for any o(n)o(n) query complexity. Our results on LCCs also immediately give locally-decodable codes (LDCs) with the same parameters

    Efficient Dynamic Approximate Distance Oracles for Vertex-Labeled Planar Graphs

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    Let GG be a graph where each vertex is associated with a label. A Vertex-Labeled Approximate Distance Oracle is a data structure that, given a vertex vv and a label λ\lambda, returns a (1+ε)(1+\varepsilon)-approximation of the distance from vv to the closest vertex with label λ\lambda in GG. Such an oracle is dynamic if it also supports label changes. In this paper we present three different dynamic approximate vertex-labeled distance oracles for planar graphs, all with polylogarithmic query and update times, and nearly linear space requirements

    Verification of Hierarchical Artifact Systems

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    Data-driven workflows, of which IBM's Business Artifacts are a prime exponent, have been successfully deployed in practice, adopted in industrial standards, and have spawned a rich body of research in academia, focused primarily on static analysis. The present work represents a significant advance on the problem of artifact verification, by considering a much richer and more realistic model than in previous work, incorporating core elements of IBM's successful Guard-Stage-Milestone model. In particular, the model features task hierarchy, concurrency, and richer artifact data. It also allows database key and foreign key dependencies, as well as arithmetic constraints. The results show decidability of verification and establish its complexity, making use of novel techniques including a hierarchy of Vector Addition Systems and a variant of quantifier elimination tailored to our context.Comment: Full version of the accepted PODS pape

    Influence of probiotic bacterium Lactobacillus acidophilus on the survival and growth of pearl oyster Pinctada fucata spat

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    Combination of micro-alga Chaetoceros calcitrans and the probiotic bacterium Lactobacillus acidophilus evaluated at 1:1 and 1:2 levels revealed that in the probiotic treated group, Pinctada fucata spat registered significantly high survival of 79.7 and 89.0 % (P<0.05) respectively compared to that of 65.0 % survival in control. The probiotic treated groups also showed significant improvement in growth in terms of length and weight as compared to the control group. The probiotic treated spat attained a weight gain of 346.0 ± 1.57 mg (1:1 level) and 382.0 ± 11.76 mg (1:2 level) compared to 296.4 ± 9.04 mg in control group. The length in terms of dorso-ventral measurement (DVM) increased to 18.68 mm (1:1 level) and 19.6 (1:2 level) mm compared to 13.56 mm in control group

    Captive Breeding and Nursery Rearing of the Indian Seahorse, Hippocampus kuda (Teleostei: Syngnathidae)

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    Breeding of laboratory-reared 21 pairs of broodstock Hippocampus kuda (Bleeker 1852) and rearing of their young ones indicated that 262.00 ± 59.00 offsprings were released during each spawning. A newly born seahorse was (mean ± SE) 7.83 ± 0.11 mm in length with a weight of 1.17 ± 0.009 mg. It could attain a mean length of 31.14 ± 0.66 mm with a mean weight of 16.13 ± 0.60 mg in 30 days when fed ad libitum with Artemia nauplii. The mean survival per brood cycle was enhanced to 65.22 ± 1.87% from almost less than 1.0% by improving the rearing conditions

    Relaxation through homogenization for optimal design problems with gradient constraints

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    The problem of the relaxation of optimal design problems for multiphase composite structures in the presence of constraints on the gradient of the state variable is addressed. A relaxed formulation for the problem is given in the presence of either a finite or infinite number of constraints. The relaxed formulation is used to identify minimizing sequences of configurations of phases
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