16,045 research outputs found

    A coupling model for quasi-normal modes of photonic resonators

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    We develop a model for the coupling of quasi-normal modes in open photonic systems consisting of two resonators. By expressing the modes of the coupled system as a linear combination of the modes of the individual particles, we obtain a generalized eigenvalue problem involving small size dense matrices. We apply this technique to dielectric rod dimmer of rectangular cross section for Transverse Electric (TE) polarization in a two-dimensional (2D) setup. The results of our model show excellent agreement with full-wave finite element simulations. We provide a convergence analysis, and a simplified model with a few modes to study the influence of the relative position of the two resonators. This model provides interesting physical insights on the coupling scheme at stake in such systems and pave the way for systematic and efficient design and optimization of resonances in more complicated systems, for applications including sensing, antennae and spectral filtering

    Runtime Analysis for Self-adaptive Mutation Rates

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    We propose and analyze a self-adaptive version of the (1,λ)(1,\lambda) evolutionary algorithm in which the current mutation rate is part of the individual and thus also subject to mutation. A rigorous runtime analysis on the OneMax benchmark function reveals that a simple local mutation scheme for the rate leads to an expected optimization time (number of fitness evaluations) of O(nλ/log⁥λ+nlog⁥n)O(n\lambda/\log\lambda+n\log n) when λ\lambda is at least Cln⁥nC \ln n for some constant C>0C > 0. For all values of λ≄Cln⁥n\lambda \ge C \ln n, this performance is asymptotically best possible among all λ\lambda-parallel mutation-based unbiased black-box algorithms. Our result shows that self-adaptation in evolutionary computation can find complex optimal parameter settings on the fly. At the same time, it proves that a relatively complicated self-adjusting scheme for the mutation rate proposed by Doerr, Gie{\ss}en, Witt, and Yang~(GECCO~2017) can be replaced by our simple endogenous scheme. On the technical side, the paper contributes new tools for the analysis of two-dimensional drift processes arising in the analysis of dynamic parameter choices in EAs, including bounds on occupation probabilities in processes with non-constant drift

    Perfect state transfer, graph products and equitable partitions

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    We describe new constructions of graphs which exhibit perfect state transfer on continuous-time quantum walks. Our constructions are based on variants of the double cones [BCMS09,ANOPRT10,ANOPRT09] and the Cartesian graph products (which includes the n-cube) [CDDEKL05]. Some of our results include: (1) If GG is a graph with perfect state transfer at time tGt_{G}, where t_{G}\Spec(G) \subseteq \ZZ\pi, and HH is a circulant with odd eigenvalues, their weak product G×HG \times H has perfect state transfer. Also, if HH is a regular graph with perfect state transfer at time tHt_{H} and GG is a graph where t_{H}|V_{H}|\Spec(G) \subseteq 2\ZZ\pi, their lexicographic product G[H]G[H] has perfect state transfer. (2) The double cone K‟2+G\overline{K}_{2} + G on any connected graph GG, has perfect state transfer if the weights of the cone edges are proportional to the Perron eigenvector of GG. This generalizes results for double cone on regular graphs studied in [BCMS09,ANOPRT10,ANOPRT09]. (3) For an infinite family \GG of regular graphs, there is a circulant connection so the graph K_{1}+\GG\circ\GG+K_{1} has perfect state transfer. In contrast, no perfect state transfer exists if a complete bipartite connection is used (even in the presence of weights) [ANOPRT09]. We also describe a generalization of the path collapsing argument [CCDFGS03,CDDEKL05], which reduces questions about perfect state transfer to simpler (weighted) multigraphs, for graphs with equitable distance partitions.Comment: 18 pages, 6 figure

    An average-case depth hierarchy theorem for Boolean circuits

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    We prove an average-case depth hierarchy theorem for Boolean circuits over the standard basis of AND\mathsf{AND}, OR\mathsf{OR}, and NOT\mathsf{NOT} gates. Our hierarchy theorem says that for every d≄2d \geq 2, there is an explicit nn-variable Boolean function ff, computed by a linear-size depth-dd formula, which is such that any depth-(d−1)(d-1) circuit that agrees with ff on (1/2+on(1))(1/2 + o_n(1)) fraction of all inputs must have size exp⁥(nΩ(1/d)).\exp({n^{\Omega(1/d)}}). This answers an open question posed by H{\aa}stad in his Ph.D. thesis. Our average-case depth hierarchy theorem implies that the polynomial hierarchy is infinite relative to a random oracle with probability 1, confirming a conjecture of H{\aa}stad, Cai, and Babai. We also use our result to show that there is no "approximate converse" to the results of Linial, Mansour, Nisan and Boppana on the total influence of small-depth circuits, thus answering a question posed by O'Donnell, Kalai, and Hatami. A key ingredient in our proof is a notion of \emph{random projections} which generalize random restrictions

    Frozen Soil Lateral Resistance for the Seismic Design of Highway Bridge Foundations

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    INE/AUTC 12.3
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