3,341 research outputs found

    A new ADMM algorithm for the Euclidean median and its application to robust patch regression

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    The Euclidean Median (EM) of a set of points Ω\Omega in an Euclidean space is the point x minimizing the (weighted) sum of the Euclidean distances of x to the points in Ω\Omega. While there exits no closed-form expression for the EM, it can nevertheless be computed using iterative methods such as the Wieszfeld algorithm. The EM has classically been used as a robust estimator of centrality for multivariate data. It was recently demonstrated that the EM can be used to perform robust patch-based denoising of images by generalizing the popular Non-Local Means algorithm. In this paper, we propose a novel algorithm for computing the EM (and its box-constrained counterpart) using variable splitting and the method of augmented Lagrangian. The attractive feature of this approach is that the subproblems involved in the ADMM-based optimization of the augmented Lagrangian can be resolved using simple closed-form projections. The proposed ADMM solver is used for robust patch-based image denoising and is shown to exhibit faster convergence compared to an existing solver.Comment: 5 pages, 3 figures, 1 table. To appear in Proc. IEEE International Conference on Acoustics, Speech, and Signal Processing, April 19-24, 201

    A computer program to predict rotor rotational noise of a stationary rotor from blade loading coefficient

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    The programing language used is FORTRAN IV. A description of all main and subprograms is provided so that any user possessing a FORTRAN compiler and random access capability can adapt the program to his facility. Rotor blade surface-pressure spectra can be used by the program to calculate: (1) blade station loading spectra, (2) chordwise and/or spanwise integrated blade-loading spectra, and (3) far-field rotational noise spectra. Any of five standard inline functions describing the chordwise distribution of the blade loading can be chosen in order to study parametrically the acoustic predictions. The program output consists of both printed and graphic descriptions of the blade-loading coefficient spectra and far-field acoustic spectrum. The results may also be written on binary file for future processing. Examples of the application of the program along with a description of the rotational noise prediction theory on which the program is based are also provided

    Zero Temperature Insulator-Metal Transition in Doped Manganites

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    We study the transition at T=0 from a ferromagnetic insulating to a ferromagnetic metallic phase in manganites as a function of hole doping using an effective low-energy model Hamiltonian proposed by us recently. The model incorporates the quantum nature of the dynamic Jahn-Teller(JT) phonons strongly coupled to orbitally degenerate electrons as well as strong Coulomb correlation effects and leads naturally to the coexistence of localized (JT polaronic) and band-like electronic states. We study the insulator-metal transition as a function of doping as well as of the correlation strength U and JT gain in energy E_{JT}, and find, for realistic values of parameters, a ground state phase diagram in agreement with experiments. We also discuss how several other features of manganites as well as differences in behaviour among manganites can be understood in terms of our model.Comment: To be published in Europhysics Letter

    New age data on the geological evolution of Southern India

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    The Peninsular Gneisses of Southern India developed over a period of several hundred Ma in the middle-to-late Archaean. Gneisses in the Gorur-Hassan area of southern Karnataka are the oldest recognized constituents: Beckinsale et al. reported a preliminary Rb-Sr whole-rock isochron age of 33558 + or - 66 Ma, but further Rb-Sr and Pb/Pb whole-rock isochron determinations indicate a slightly younger, though more precise age of ca 3305 Ma (R. D. Beckinsale, Pers. Comm.). It is well established that the Peninsular Gneisses constitute basement on which the Dharwar schist belts were deposited. Well-documented exposures of unconformities, with basal quartz pebble conglomerates of the Dharwar Supergroup overlying Peninsular Gneisses, have been reported from the Chikmagalur and Chitradurga areas, and basement gneisses in these two areas have been dated by Rb-Sr and Pb/Pb whole-rock isochron methods at ca 3150 Ma and ca 3000 Ma respectively. Dharwar supracrustal rocks of the Chitradurga schist belt are intruded by the Chitradurga Granite, dated by a Pb/Pb whole-rock isochron at 2605 + or - 18 Ma. These results indicate that the Dharwar Supergroup in the Chitradurga belt was deposited between 3000 Ma and 2600 Ma

    Regeneration of Indian maize genotypes (Zea mays L.) from immature embryo culture through callus induction

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    Callus induction and regeneration ability of five maize genotypes UMI 757, UMI 615, UMI 112, UMI 285 and CO 1 and one promising maize hybrids COH(M) 5 were investigated using 14 days old immature embryos as explants. Callus induction depends on genotype, explants (age and size of explants), medium, type of auxin and their concentration. Explants grown on Murashige and Skoog (MS) medium supplemented with 1.5 mg/l 2, 4 - D (2,4 – dichloro phenoxy acetic acid), 0.3 mg/l kinetin with 30 g/l maltose showed the highest percentage of embryogenic callus induction. Among the six genotypes tested, COH(M) 5 maize hybrids have highest percentage of embryogenic calli. The embryogenic calli incubated on MS medium supplemented with 1.5 mg/l BAP (Benzyl Amino Purine), 0.2 mg/lNAA (Naphthalene Acetic Acid) with 1.0 mg/l kinetin was found to give the highest organogenesis response and regeneration of plantlets

    Coulomb Interactions and Nanoscale Electronic Inhomogeneities in Manganites

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    We address the issue of endemic electronic inhomogeneities in manganites using extensive simulations on a new model with Coulomb interactions amongst two electronic fluids, one localized (polaronic), the other extended (band-like), and dopant ions. The long range Coulomb interactions frustrate phase separation induced by the strong on site repulsion between the fluids. A single quantum phase ensues which is intrinsically and strongly inhomogeneous at a nano-scale, but homogeneous on meso-scales, with many characteristics (including colossal responses)that agree with experiments. This, we argue, is the origin of nanoscale inhomogeneities in manganites, rather than phase competition and disorder related effects as often proposed.Comment: 4 pages, 3 figure

    Effect of harmones on callus induction in Maize (Zea mays L.)

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    Callus induction from explants is a critical process in regeneration, micropropagation and transformation of maize (Zea mays L.) plants. Formation of callus from plant tissues on culture is affected by several factors. This study revealed to establish the effect of genotype, source of explants and auxin concentration on callus induction from five genotypes UMI 757 (G1), UMI 615 (G2), UMI 112 (G3), UMI 285 (G4) and CO 1 (G5) and one hybrid CO H (M) 5 (G6). Callus induction of the six maize varieties was investigated using immature embryos (E1), leaf bits (E2), root tips (E3), hypocotyls (E4) and seeds (E5) as explants with different concentrations of hormones. In this study, immature embryo was taken from 10 to 12 days after pollination (DAP) to get maximum response. The highest percentage of callus induction was observed (99.10) in immature embryo culture and seed culture gave the highest percentage of rhizogenic callus formation when compare to immature embryo. Among the genotypes tested, CO H (M) 5 recorded the highest callus induction percentage on (2D2K2) medium composition

    Theory of Insulator Metal Transition and Colossal Magnetoresistance in Doped Manganites

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    The persistent proximity of insulating and metallic phases, a puzzling characterestic of manganites, is argued to arise from the self organization of the twofold degenerate e_g orbitals of Mn into localized Jahn-Teller(JT) polaronic levels and broad band states due to the large electron - JT phonon coupling present in them. We describe a new two band model with strong correlations and a dynamical mean-field theory calculation of equilibrium and transport properties. These explain the insulator metal transition and colossal magnetoresistance quantitatively, as well as other consequences of two state coexistence
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