272 research outputs found

    Application of Ant Colony Optmization to the Routing and Wavelength Assignment problem

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    The transmission capacity of a link in today's optical networks has increased significantly due to wavelength-division multiplexing (WDM) technology. A unique feature of optical WDM networks is tight coupling between routing and wavelength selection. A lightpath is implemented by selecting a set or sequence of physical links between the source and destination nodes, and reserving a wavelength on each of these links for the lightpath. Thus, in establishing an optical connection we must deal with both routing (selecting a suitable path, i.e., sequence of physical links) and wavelength assignment (allocating an available wavelength for the connection (source-destination pair)). The resulting problem is referred to as the routing and wavelength assignment (RWA) problem, and is significantly more difficult than the routing problem in electrical networks. In this thesis, we offer a new heuristic algorithm to solve the RWA problem using Ant Colony Optimization (ACO) meta-heuristic. An edge disjoint path problem and a partition coloring problem are used to formulate the algorithm

    A Review on the Computational Methods for Emotional State Estimation from the Human EEG

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    A growing number of affective computing researches recently developed a computer system that can recognize an emotional state of the human user to establish affective human-computer interactions. Various measures have been used to estimate emotional states, including self-report, startle response, behavioral response, autonomic measurement, and neurophysiologic measurement. Among them, inferring emotional states from electroencephalography (EEG) has received considerable attention as EEG could directly reflect emotional states with relatively low costs and simplicity. Yet, EEG-based emotional state estimation requires well-designed computational methods to extract information from complex and noisy multichannel EEG data. In this paper, we review the computational methods that have been developed to deduct EEG indices of emotion, to extract emotion-related features, or to classify EEG signals into one of many emotional states. We also propose using sequential Bayesian inference to estimate the continuous emotional state in real time. We present current challenges for building an EEG-based emotion recognition system and suggest some future directions.open

    Observation of trapped-modes excited in double-layered symmetric electric ring resonators

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    We report on experimental observations of trapped-mode resonances in double-layered symmetric electric ring resonators separated by dielectric inserts. The resulting metamaterial introduces trapped-mode resonances that were thought to be produced only by asymmetric metamaterial unit cells. Experimental verification of the newly observed trapped modes, along with the analysis of the stacked metamaterial geometry reported in this paper, opens an alternative way of forming sharp resonances in a symmetric metamaterial structure extended in all three dimensions.open9
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