6,244 research outputs found

    Economical Valuation of Hypothetically Constructed Washland around a Wetland

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    Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

    Relaxed 2-D Principal Component Analysis by LpL_p Norm for Face Recognition

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    A relaxed two dimensional principal component analysis (R2DPCA) approach is proposed for face recognition. Different to the 2DPCA, 2DPCA-L1L_1 and G2DPCA, the R2DPCA utilizes the label information (if known) of training samples to calculate a relaxation vector and presents a weight to each subset of training data. A new relaxed scatter matrix is defined and the computed projection axes are able to increase the accuracy of face recognition. The optimal LpL_p-norms are selected in a reasonable range. Numerical experiments on practical face databased indicate that the R2DPCA has high generalization ability and can achieve a higher recognition rate than state-of-the-art methods.Comment: 19 pages, 11 figure

    Monte Carlo Simulation of Sinusoidally Modulated Superlattice Growth

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    The fabrication of ZnSe/ZnTe superlattices grown by the process of rotating the substrate in the presence of an inhomogeneous flux distribution instead of successively closing and opening of source shutters is studied via Monte Carlo simulations. It is found that the concentration of each compound is sinusoidally modulated along the growth direction, caused by the uneven arrival of Se and Te atoms at a given point of the sample, and by the variation of the Te/Se ratio at that point due to the rotation of the substrate. In this way we obtain a ZnSe1x_{1-x}Tex_x alloy in which the composition xx varies sinusoidally along the growth direction. The period of the modulation is directly controlled by the rate of the substrate rotation. The amplitude of the compositional modulation is monotonous for small angular velocities of the substrate rotation, but is itself modulated for large angular velocities. The average amplitude of the modulation pattern decreases as the angular velocity of substrate rotation increases and the measurement position approaches the center of rotation. The simulation results are in good agreement with previously published experimental measurements on superlattices fabricated in this manner

    Spatiotemporal correlations of handset-based service usages

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    We study spatiotemporal correlations and temporal diversities of handset-based service usages by analyzing a dataset that includes detailed information about locations and service usages of 124 users over 16 months. By constructing the spatiotemporal trajectories of the users we detect several meaningful places or contexts for each one of them and show how the context affects the service usage patterns. We find that temporal patterns of service usages are bound to the typical weekly cycles of humans, yet they show maximal activities at different times. We first discuss their temporal correlations and then investigate the time-ordering behavior of communication services like calls being followed by the non-communication services like applications. We also find that the behavioral overlap network based on the clustering of temporal patterns is comparable to the communication network of users. Our approach provides a useful framework for handset-based data analysis and helps us to understand the complexities of information and communications technology enabled human behavior.Comment: 11 pages, 15 figure

    Spin entropy as the likely source of enhanced thermopower in $\rm\bf Na_xCo_2O_4

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    In an electric field, the flow of electrons in a solid produces an entropy current in addition to the familiar charge current. This Peltier effect underlies all thermoelectric refrigerators. The upsurge in thermoelectric cooling applications has led to a search for more efficient Peltier materials and to renewed theoretical interest in how electron-electron interaction may enhance the thermopower QQ of materials such as the transition-metal oxides \cite{Mahan,Beni,Kotliar,Chaikin}. An important factor in this enhancement is the electronic spin entropy, which is predicted \cite{Chaikin,Kwak,KwakChaikin} to dominate the entropy current. Here we report evidence for such suppression in the layered oxide NaxCo2O4\rm Na_xCo_2O_4, and present evidence that it is a strong-correlation effect.Comment: 5 pages, 5 figures, already publishe

    Effects of Promoter on the Formation of Gas Hydrate from Blast furnace Gas

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    DNA-decorated carbon nanotube-based FETs as ultrasensitive chemical sensors: Discrimination of homologues, structural isomers, and optical isomers

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    We have explored the abilities of all-electronic DNA-carbon nanotube (DNA-NT) vapor sensors to discriminate very similar classes ofmolecules.We screened hundreds ofDNA-NT devices against a panel of compounds chosen because of their similarities. We demonstrated that DNA-NT vapor sensors readily discriminate between series of chemical homologues that differ by single methyl groups. DNA-NT devices also discriminate among structural isomers and optical isomers, a trait common in biological olfactory systems, but only recently demonstrated for electronic FET based chemical sensors

    Analytical study of quality-biased competition dynamics for memes in social media

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    The spreading of news, memes and other pieces of information occurring via online social platforms has a strong and growing impact on our modern societies, with enormous consequences, that may be beneficial but also catastrophic. In this work we consider a recently introduced model for information diffusion in social media taking explicitly into account the competition of a large number of items of diverse quality. We map the meme dynamics onto a one-dimensional diffusion process that we solve analytically, deriving the lifetime and popularity distributions of individual memes. We also present a mean-field type of approach that reproduces the average stationary properties of the dynamics. In this way we understand and control the role of the different ingredients of the model, opening the path for the inclusion of additional, more realistic, features.Comment: 6 pages + 9 pages of Supplementary Materia

    Spin-density-wave transition of (TMTSF)2_2PF6_6 at high magnetic fields

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    The transverse magnetoresistance of the Bechgaard salt (TMTSF)2_2PF6_6 has been measured for various pressures, with the field up to 24 T parallel to the lowest conductivity direction c^{\ast}. A quadratic behavior is observed in the magnetic field dependence of the spin-density-wave (SDW) transition temperature TSDWT_{\rm {SDW}}. With increasing pressure, TSDWT_{\rm {SDW}} decreases and the coefficient of the quadratic term increases. These results are consistent with the prediction of the mean-field theory based on the nesting of the quasi one-dimensional Fermi surface. Using a mean field theory, TSDWT_{\rm {SDW}} for the perfect nesting case is estimated as about 16 K. This means that even at ambient pressure where TSDWT_{\rm {SDW}} is 12 K, the SDW phase of (TMTSF)2_2PF6_6 is substantially suppressed by the two-dimensionality of the system.Comment: 11pages,6figures(EPS), accepted for publication in PR
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