19,879 research outputs found

    Self-Intersection Number of BPS Junctions in Backgrounds of Three and Seven-Branes

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    In a recent paper DeWolfe et al. have shown how to use the self-intersection number of junctions to constrain the BPS spectrum of N=2, D=4 theories with ADE flavor symmetry arising on a single D3-brane probe in a 7-brane background. Motivated by the existence of more general N=2, D=4 theories arising on the worldvolume of multiple D3-brane probes we show how to compute the self-intersection number of junctions in the presence of 7-branes and multiple D3-branes.Comment: 10 pages, Latex, 2 figure

    Adaptive beamforming of steerable array monopole antenna for WLAN application

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    The modern communication systems are using smart portable devices that operate on WLAN frequency of 2.45 GHz. One of the serious limitations of handled devices is difficult to achieve a direct connection between the transmitter and receiver. Therefore, a smart steerable patter array antenna is highly recommended for new generation communication. Using low-cost steerable passive monopole array antenna can achieve a beam steering and high gain. Loading an additional reactance to the passive elements of the array are changed the mutual coupling between the arrays, which leads to steering the pattern to the desired direction. However, this needs fast process accurate optimised parameters. In this study, four passives one active monopole array antenna is proposed and simulated by using CST Microwave Studio software. The adaptive beamforming is proposed by using downhill simplex algorithm. The results show that the optimum reactance values are suggested after 0.074 second with 94 iterations to achieve a direction of arrival of 180° and 0°. The simulated radiation is successfully steered to the direction of 180 ° by adding the suggested reactance into the passive elements. Furthermore, the antenna gain is improved by 1.3 dBi that achieved a value of 5.3 dBi.The envelope-cross-correlation (ECC) shows magnitudes less than 0.5 among the elements. This algorithm successfully is provided with the optimum reactance values. The proposed approach can be considered a fast and significant candidate for new generation of smart communication WLAN applications

    Membership of the 109th Congress: A Profile

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    [From Summary] This report presents a profile of the membership of the 109th Congress. Statistical information is included on selected characteristics of Members. This includes data on party affiliation; average age and length of service; occupation; religious affiliation; female and minority Members; foreign-born Members; and military service

    Identification of Nonlinear Systems Using Radial Basis Function Neural Network

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    This paper uses the radial basis function neural network (RBFNN) for system identification of nonlinear systems. Five nonlinear systems are used to examine the activity of RBFNN in system modeling of nonlinear systems; the five nonlinear systems are dual tank system, single tank system, DC motor system, and two academic models. The feed forward method is considered in this work for modelling the non-linear dynamic models, where the KMeans clustering algorithm used in this paper to select the centers of radial basis function network, because it is reliable, offers fast convergence and can handle large data sets. The least mean square method is used to adjust the weights to the output layer, and Euclidean distance method used to measure the width of the Gaussian function

    Del Pezzo Surfaces and Affine 7-brane Backgrounds

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    A map between string junctions in the affine 7-brane backgrounds and vector bundles on del Pezzo surfaces is constructed using mirror symmetry. It is shown that the lattice of string junctions with support on an affine 7-brane configuration is isomorphic to the K-theory group of the corresponding del Pezzo surface. This isomorphism allows us to construct a map between the states of the N=2, D=4 theories with E_N global symmetry realized in two different ways in Type IIB and Type IIA string theory. A subgroup of the SL(2,Z) symmetry of the \hat{E}_9 7-brane background appears as the Fourier-Mukai transform acting on the D-brane configurations realizing vector bundles on elliptically fibered B_9.Comment: 19 pages, LaTeX, 2 eps figures. v2: minor changes, version to appear in JHE
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