857 research outputs found

    Modeling the Temporal Nature of Human Behavior for Demographics Prediction

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    Mobile phone metadata is increasingly used for humanitarian purposes in developing countries as traditional data is scarce. Basic demographic information is however often absent from mobile phone datasets, limiting the operational impact of the datasets. For these reasons, there has been a growing interest in predicting demographic information from mobile phone metadata. Previous work focused on creating increasingly advanced features to be modeled with standard machine learning algorithms. We here instead model the raw mobile phone metadata directly using deep learning, exploiting the temporal nature of the patterns in the data. From high-level assumptions we design a data representation and convolutional network architecture for modeling patterns within a week. We then examine three strategies for aggregating patterns across weeks and show that our method reaches state-of-the-art accuracy on both age and gender prediction using only the temporal modality in mobile metadata. We finally validate our method on low activity users and evaluate the modeling assumptions.Comment: Accepted at ECML 2017. A previous version of this paper was titled 'Using Deep Learning to Predict Demographics from Mobile Phone Metadata' and was accepted at the ICLR 2016 worksho

    Density-functional embedding using a plane-wave basis

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    The constrained electron density method of embedding a Kohn-Sham system in a substrate system (first described by P. Cortona, Phys. Rev. B {\bf 44}, 8454 (1991) and T.A. Wesolowski and A. Warshel, J. Phys. Chem {\bf 97}, 8050 (1993)) is applied with a plane-wave basis and both local and non-local pseudopotentials. This method divides the electron density of the system into substrate and embedded electron densities, the sum of which is the electron density of the system of interest. Coupling between the substrate and embedded systems is achieved via approximate kinetic energy functionals. Bulk aluminium is examined as a test case for which there is a strong interaction between the substrate and embedded systems. A number of approximations to the kinetic-energy functional, both semi-local and non-local, are investigated. It is found that Kohn-Sham results can be well reproduced using a non-local kinetic energy functional, with the total energy accurate to better than 0.1 eV per atom and good agreement between the electron densities.Comment: 11 pages, 4 figure

    Application of macro-fiber composite (MFC) as a piezoelectric actuator

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    The aim of the present work is to investigate the use of Macro Fiber Composite (MFC) actuator for modal analysis of composite plate. Efficiency of application of MFC as an actuator in comparison with the impact hammer, PZT actuator and modal shaker has been investigated. POLYTEC laser Vibrometer operating on the Doppler principle and measuring back-scattered light from a vibrating panel has been used to determine its vibration velocity and displacement. Modal analysis is subsequently applied to extract natural frequencies and mode shape

    Radiation Safety at FLUTE with Special Emphasis on Activation Issues

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    The accelerator FLUTE (name abbreviation derived from its German name: Ferninfrarot Linac- und TestExperiment) has been set up in cooperation with DESY and PSI [1]. The electron source and diagnostics has commenced operation. General safety issues of FLUTE are covered in this paper. The activation of the accelerator and vacuum parts were predicted previously [2]. The attention is given to the activation of aluminum and impurities in the electron absorber of the beam dump. Potential air activation in the experimental hall is also discussed

    The Energy Density in the Maxwell-Chern-Simons Theory

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    A two-dimensional nonrelativistic fermion system coupled to both electromagnetic gauge fields and Chern-Simons gauge fields is analysed. Polarization tensors relevant in the quantum Hall effect and anyon superconductivity are obtained as simple closed integrals and are evaluated numerically for all momenta and frequencies. The correction to the energy density is evaluated in the random phase approximation (RPA), by summing an infinite series of ring diagrams. It is found that the correction has significant dependence on the particle number density. In the context of anyon superconductivity, the energy density relative to the mean field value is minimized at a hole concentration per lattice plaquette (0.05 \sim 0.06) (p_c a/\hbar)^2 where p_c and a are the momentum cutoff and lattice constant, respectively. At the minimum the correction is about -5 % \sim -25 %, depending on the ratio (2m \omega_c)/(p_c^2) where \omega_c is the frequency cutoff. In the Jain-Fradkin-Lopez picture of the fractional quantum Hall effect the RPA correction to the energy density is very large. It diverges logarithmically as the cutoff is removed, implying that corrections beyond RPA become important at large momentum and frequency.Comment: 19 pages (plain Tex), 12 figures not included, UMN-TH-1246/9

    Detailed Analysis of Transverse Emittance of the FLUTE Electron Bunch

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    The com­pact and ver­sa­tile lin­ear ac­cel­er­a­tor-based test fa­cil­ity FLUTE (Fer­n­in­frarot Linac- Und Test-Ex­per­i­ment) is op­er­ated at KIT. Its pri­mary goal is to serve as a plat­form for a va­ri­ety of ac­cel­er­a­tor R\&D stud­ies like the gen­er­a­tion of strong ul­tra-short ter­a­hertz pulses. The am­pli­tude of the gen­er­ated co­her­ent THz pulses is pro­por­tional to the square num­ber of par­ti­cles in the bunch. With the trans­verse emit­tance a mea­sure for the trans­verse par­ti­cle den­sity can be de­ter­mined. It is there­fore a vital pa­ra­me­ter in the op­ti­miza­tion for op­er­a­tion. In a sys­tem­atic study, the trans­verse emit­tance of the elec­tron beam was mea­sured in the FLUTE in­jec­tor. A de­tailed analy­sis con­sid­ers dif­fer­ent in­flu­ences such as the bunch charge and com­pares this with par­ti­cle track­ing sim­u­la­tions car­ried out with ASTRA. In this con­tri­bu­tion, the key find­ings of this analy­sis are dis­cussed
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