Search results for "CONSTANT"
showing 10 items of 1718 documents
Hybrid Methods for Robust Irradiance Analysis and 3-D Shape Reconstruction from Images
1994
The analysis of the differential structure of images is an interesting task in machine vision, among other reasons because it can provide relevant featural representation of images, suited for higher level information processing task like geometry reconstruction and object recognition. The importance of invariants of the field of isophotae on lambertian surfaces in shape perception by means of chiaroscuro is discussed in (Koenderink and Van Doom, 1980). In their approach to shape from shading, (Breton et al, 1992) represent the shading of the image by means of its shading flow field, i.e. by the first order differential structure of the image expressed as the isoluminance direction and grad…
Fracture and Fatigue of Travelling Plates
2013
In this chapter, problems of fracture and stability of a moving plate, travelling in a system of rollers at a constant velocity, are studied. It is known that in the manufacturing process, there may occur many kinds of defects in the paper web, such as edge cracks and blister and fiber cuts. Our aim is to tackle this problem and analyse theoretically how the defects change the behaviour. We will use the model of a thin elastic plate made of brittle material. A plate with initial cracks is studied, subjected to constant tension and cyclic tension. As a result, we will show how to find safe parameter ranges of transport velocities and in-plane tensions when fracture, stability and constraints…
Zinc-blende AlN and GaN under pressure: structural, electronic, elastic and piezoelectric properties
2004
In this paper we report a theoretical study of the structural, elastic, electronic and piezoelectric properties of zinc-blende AlN and GaN under the pressure effect. The study is focused on the first-principles all electron full-potential augmented plane wave plus local orbitals calculations within the density-functional theory. The results of bulk properties, including lattice constants, bulk modulus and derivatives and band structures are obtained and compared using both the local density approximation (LDA) and the generalized gradient approximation (GGA) for the exchange-correlation functional. We find that the GGA does not give a significant improvement over LDA. We also report calcula…
Empirical molecular dynamics study of structural, elastic and thermodynamic properties of zinc-blende-like SiGe compound
2004
Abstract A three-body potential coupled with a molecular-dynamics method is used to calculate structural and thermodynamic properties of the hypothetical IV–IV compound SiGe in zinc-blende phase. A good agreement between the calculated and theoretical values of the lattice constant, the bulk modulus and its derivative, and the cohesive energy is obtained. We also compute the elastic constants, Debye temperature, lattice thermal expansion, and the specific heat. We investigate also, the structural properties of SiGe when rock-salt phase appears.
Enthalpies of solution and dilution of butanol and pentanol in dodecyltrimethylammonium bromide micellar solutions
1987
The enthalpies of solution and of dilution of 1-butanol and 1-pentanol were measured in micellar solutions of dodecyltrimethylammonium bromide by systematically changing the concentration of alcohols and surfactant. The enthalpies of solution at infinite dilution of alcohols at each surfactant concentration were evaluated from a linear plot. This quantity increases with surfactant concentration (up to 0.8m) with a curvature which depends on the alcohol alkyl chain length. The difficulties arising for a quantitative treatment of both the enthalpies of dilution and of solution at finite alcohol concentrations are discussed. The dependence on the surfactant concentration of the standard enthal…
Measurement of the lifetime of tau-lepton
1996
The tau lepton lifetime is measured with the L3 detector at LEP using the complete data taken at centre-of-mass energies around the Z pole resulting in tau_tau = 293.2 +/- 2.0 (stat) +/- 1.5 (syst) fs. The comparison of this result with the muon lifetime supports lepton universality of the weak charged current at the level of six per mille. Assuming lepton universality, the value of the strong coupling constant, alpha_s is found to be alpha_s(m_tau^2) = 0.319 +/- 0.015(exp.) +/- 0.014 (theory). The tau lepton lifetime is measured with the L3 detector at LEP using the complete data taken at centre-of-mass energies around the Z pole resulting in τ τ =293.2 ± 2.0 (stat) ± 1.5 (syst) fs . The c…
The one loop gluon emission light cone wave function
2017
Light cone perturbation theory has become an essential tool to calculate cross sections for various small-$x$ dilute-dense processes such as deep inelastic scattering and forward proton-proton and proton-nucleus collisions. Here we set out to do one loop calculations in an explicit helicity basis in the four dimensional helicity scheme. As a first process we calculate light cone wave function for one gluon emission to one-loop order in Hamiltonian perturbation theory on the light front. We regulate ultraviolet divergences with transverse dimensional regularization and soft divergences with using a cut-off on longitudinal momentum. We show that when all the renormalization constants are comb…
Thermal entanglement of a spin-1/2 Ising–Heisenberg model on a symmetrical diamond chain
2011
International audience; The entanglement quantum properties of a spin-1/2 Ising-Heisenberg model on a symmetrical diamond chain were analyzed. Due to the separable nature of the Ising-type exchange interactions between neighboring Heisenberg dimers, calculation of the entanglement can be performed exactly for each individual dimer. Pairwise thermal entanglement was studied in terms of the isotropic Ising-Heisenberg model and analytical expressions for the concurrence (as a measure of bipartite entanglement) were obtained. The effects of external magnetic field H and next-nearest neighbor interaction J(m) between nodal Ising sites were considered. The ground state structure and entanglement …
Interactions of Dioxouranium(VI) with Amines in Aqueous Solution
2010
The interaction of the dioxouranium(VI) ion with five low molecular weight polyamines (ethylenediamine, putrescine, cadaverine, spermidine, and spermine) and with poly(allyl)amine (15 kDa) was studied potentiometrically (ISE-H + glass electrode) at T ) 298.15 K. Investigations were carried out in NaNO3 ionic medium, at I ) 0.1 mol · L -1 (and 0.5 mol · L -1 for poly(allyl)amine only), in the pH range 3.5 to 5.5, before the formation of uranyl insoluble species. The results gave evidence for the formation of two species, namely, UO2L 2+ and UO2L(OH) + for the diamine systems (ethylenediamine, putrescine, cadaverine), UO2L 2+ and UO2LH 3+ for spermidine, and UO2LH 3+ and UO2LH2 4+ for spermin…
Formation and Stability of Cadmium(II)/Phytate Complexes by Different Electrochemical Techniques. Critical Analysis of Results
2010
In the present work the stability constants of various cadmium(II)/phytate (Phy) species were determined at T = 298.15 K in NaNO3(aq) at I = 0.1 mol·L−1 by DP-ASV (Differential Pulse Anodic Stripping Voltammetry) and by potentiometric titrations using an ISE-Cd2+. Cyclic voltammograms were also recorded to check the electrochemical behavior of cadmium in the presence of phytate. The results were analyzed together with previous data determined by ISE-H+ measurements. Data obtained were used to provide an exhaustive speciation scheme for the phytate/cadmium(II) system at different conditions, as well as a comprehensive representation of the binding ability of phytate toward cadmium(II). Diffe…