Search results for " solution"
showing 10 items of 3084 documents
On the nature of macroradicals formed upon radiolysis of aqueous poly(N-vinylpyrrolidone) solutions
2020
In this work we have explored the nature of macroradicals formed upon radiolysis of aqueous poly(N-vinylpyrrolidone) (PVP) solutions using pulse radiolysis, density functional theory (DFT) and literature data. On the basis of literature data on site-specific kinetics of hydrogen abstraction from simple amides and spectra corresponding to specific radical sites on the same amides we have assessed the distribution of H-atom abstraction by `OH radicals from different positions on the pyrrolidone ring and the polymer backbone. Pulse radiolysis experiments performed at different doses per pulse and different PVP concentrations demonstrate that the H-abstracting radiolysis products are not quanti…
Hydrodynamics of the cocurrent downflow of a gas and a foaming liquid through a packed bed. Part I. Estimation of the transition boundary between the…
2004
Abstract In the study the results of investigations are presented aimed at determining such values of the operating parameters for which the change of the hydrodynamic regime occurs from the gas continuous flow (GCF) to the pulsing flow (PF). Nitrogen, helium and argon were used as the gas phase while the liquid phase was formed by the aqueous solutions of the alcohols C 1 –C 4 of the concentrations which ensured the foaming of the system. Thus a wide range of physicochemical properties of the system was covered in the experiments. The present study, as well as Part II, contain a wealth of experimental data which characterise the PF through the packing for the foam-forming systems. It is de…
Effect of cation disorder on the magnetic properties ofSr2Fe1−xGaxReO6(0<x<0.7)double perovskites
2007
The effect of diamagnetic dilution of the Fe sublattice on the structural and magnetic properties of the double perovskite Sr{sub 2}Fe{sub 1-x}Ga{sub x}ReO{sub 6} (0 =}0.4 is detected by x-ray structural analysis accompanied by the observation of a magnetically ordered and a paramagnetic phase in the corresponding Moessbauer spectra. Below 20% Ga content, Ga statistically dilutes the -Fe-O-Re-O-Fe- double-exchange pathways. Phase separation begins at 20% Ga substitution; between 20% and 40% ofmore » Ga content, the paramagnetic Ga-based phase does not contain any Fe. The Fe-containing, paramagnetic cubic phases which can be detected by Moessbauer spectroscopy first appear for x=0.4.« less
Efficacy and safety of preoperative with Lugol's iodine solution euthyroid patients with Graves' disease (LIGRADIS Trial): study protocol for a multi…
2021
"Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAM"
Singular integrals, analytic capacity and rectifiability
1997
In this survey we study some interplay between classical complex analysis (removable sets for bounded analytic functions), harmonic analysis (singular integrals), and geometric measure theory (rectifiability).
A note on the analytic solutions of the Camassa-Holm equation
2005
Abstract In this Note we are concerned with the well-posedness of the Camassa–Holm equation in analytic function spaces. Using the Abstract Cauchy–Kowalewski Theorem we prove that the Camassa–Holm equation admits, locally in time, a unique analytic solution. Moreover, if the initial data is real analytic, belongs to H s ( R ) with s > 3 / 2 , ‖ u 0 ‖ L 1 ∞ and u 0 − u 0 x x does not change sign, we prove that the solution stays analytic globally in time. To cite this article: M.C. Lombardo et al., C. R. Acad. Sci. Paris, Ser. I 341 (2005).
Walsh function analysis of 2-D generalized continuous systems
1990
The importance of the generalized or singular 2D continuous systems are demonstrated by showing their use in the solution of partial differential equations in two variables. A technique is presented for solving these systems in terms of Walsh functions. The method replaces the solution of a two-variable partial differential equation with the solution of a linear algebraic generalized 2D Sylvester equation. An efficient technique for the recursive solution of the latter equation is offered. All the results apply also in the usual Roesser 2D state-space case. >
Anisotropic potential of velocity fields in real fluids: Application to the MAST solution of shallow water equations
2013
In the present paper it is first shown that, due to their structure, the general governing equations of uncompressible real fluids can be regarded as an "anisotropic" potential flow problem and closed streamlines cannot occur at any time. For a discretized velocity field, a fast iterative procedure is proposed to order the computational elements at the beginning of each time level, allowing a sequential solution element by element of the advection problem. Some closed circuits could appear due to the discretization error and the elements involved in these circuits could not be ordered. We prove in the paper that the total flux of these not ordered elements goes to zero by refining the compu…
Numerical experiments with single mode gyrotron equations
2012
Gyrotrons are microwave sources whose operation is based on the stimulated cyclotron radiation of electrons oscillating in a static magnetic field. This process is described by the system of two complex differential equations: nonlinear first order ordinary differential equation with parameter (averaged equation of electron motion) and second order partial differential equation for high frequency field (RF field) in resonator (Schrödinger type equation for the wave amplitude). The stationary problem of the single mode gyrotron equation in short time interval with real initial conditions was numerically examined in our earlier work. In this paper we consider the stationary and nonstationary …
Regularity and polar sets for supersolutions of certain degenerate elliptic equations
1988
On considere l'equation ⊇•⊇ h F(x,⊇u(x))=0. Cette equation est non lineaire et degeneree avec des coefficients mesurables. On etudie la regularite des supersolutions