1,218 research outputs found

    Compressible primitive equation: formal derivation and stability of weak solutions

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    We present a formal derivation of a simplified version of Compressible Primitive Equations (CPEs) for atmosphere modeling. They are obtained from 33-D compressible Navier-Stokes equations with an \emph{anisotropic viscous stress tensor} where viscosity depends on the density. We then study the stability of the weak solutions of this model by using an intermediate model, called model problem, which is more simple and practical, to achieve the main result

    Sensitivity analysis of 1-d steady forced scalar conservation laws

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    We analyze 1 - d forced steady state scalar conservation laws. We first show the existence and uniqueness of entropy solutions as limits as t→ ∞ of the corresponding solutions of the scalar evolutionary hyperbolic conservation law. We then linearize the steady state equation with respect to perturbations of the forcing term. This leads to a linear first order differential equation with, possibly, discontinuous coefficients. We show the existence and uniqueness of solutions in the context of duality solutions. We also show that this system corresponds to the steady state version of the linearized evolutionary hyperbolic conservation law. This analysis leads us to the study of the sensitivity of the shock location with respect to variations of the forcing term, an issue that is relevant in applications to optimal control and parameter identification problems

    A Model-Based Approach for Compression of Fingerprint Images

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    We propose a new fingerprint image compression scheme based on the hybrid model of an image. Our scheme uses the essential steps of a typical automated fingerprint identification system (AFIS) such as enhancement, binarization and thinning to encode fingerprint images. The decoding process is based on reconstructing a hybrid surface by using the gray values on ridges and valleys. In this compression scheme, the ridge skeleton is coded efficiently by using differential chain codes. The valley skeleton is derived from the ridge skeleton and the gray values along the ridge and valley skeletons are encoded using the discrete cosine transform. The error between the original and the replica is also encoded to increase the quality. One advantage of our approach is that original features such as end points and bifurcation points can be extracted directly from compressed image even for a very high compression ratio. Another advantage is that the proposed scheme can be integrated to a typical AFIS easily. The algorithm has been applied to various fingerprint images, and high compression ratios like 63:1 have been obtained. A comparison to wavelet/scalar quantization (WSQ) has been also made

    Interplay of nematic and magnetic orders in FeSe under pressure

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    We offer an explanation for the recently observed pressure-induced magnetic state in the iron-chalcogenide FeSe based on \textit{ab initio} estimates for the pressure evolution of the most important Coulomb interaction parameters. We find that an increase of pressure leads to an overall decrease mostly in the nearest-neighbor Coulomb repulsion, which in turn leads to a reduction of the nematic order and the generation of magnetic stripe order. We treat the concomitant effects of band renormalization and the induced interplay of nematic and magnetic order in a self-consistent way and determine the generic topology of the temperature-pressure phase diagram, and find qualitative agreement with the experimentally determined phase diagram.Comment: 13 pages, 6 fig

    Generalized Timelike Mannheim Curves in Minkowski space-time E14E_1^4

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    We give a definition of generalized timelike Mannheim curve in Minkowski space-time E14E_1^4. The necessary and sufficient conditions for the generalized timelike Mannheim curve obtain. We show some characterizations of generalized Mannheim curve

    Effects of humidity level and IBA dose application on the softwood top cuttings of white mulberry (Morus alba L.) and black mulberry (Morus nigra L.) types

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    In this research, the effects of 85-90% relative humidity and ındol-3-butyric acid (IBA) doses on softwood top cuttings of two black mulberry (Types 1 and 2) and one white mulberry (Type 3) types were studied. Cuttings were taken from early June (14 Haziran) and applied to the different IBA doses (0, 1000, 2000, 3000 and 4000 ppm). Cuttings were planted in pumice medium under misting system in the greenhouse for 48 days in order to root. The highest rooting percentage was determined from Type 1 (black mulberry) in 2000 and 3000 ppm IBA doses application (100%). The lowest one was control group from Type 2 (black mulberry) which was not rooted. Acording to increase liveliness of the cuttings, rooting percentage increased. Nearly all of the living cuttings were rooted. The highest ratio of cutting callus formation was found to be 2000 and 3000 ppm IBA doses (100%) from Type 1; the lowest one was determined control group of Types 2 and 3 (0.00%). The highest rooting area lenght was found from Type 3 (2.00 cm) and Type 1 (1.92 cm); the lowest one was control group of Type 2 (0.00 cm). With respect to root numbers, the highest value was found from Type 3 (21.73 number/cutting) and Type1 (16.42 number/cutting); the lowest one was control group of Type 2 (0.00 number/cutting). The longest root was determined from 3000 ppm IBA dose of Type 1 (11.23 cm); the highest root branching value was found from Type 3 in 3000 ppm IBA dose (16.20 number/cutting) application
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