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21.
Jessica F. Burkhart Neil J. Calkin Shuhong Gao Justine C. Hyde-Volpe Kevin James Hiren Maharaj Shelly Manber Jared Ruiz Ethan Smith 《Designs, Codes and Cryptography》2009,51(3):301-314
In this paper, we recursively construct explicit elements of provably high order in finite fields. We do this using the recursive
formulas developed by Elkies to describe explicit modular towers. In particular, we give two explicit constructions based
on two examples of his formulas and demonstrate that the resulting elements have high order. Between the two constructions,
we are able to generate high order elements in every characteristic. Despite the use of the modular recursions of Elkies,
our methods are quite elementary and require no knowledge of modular curves. We compare our results to a recent result of
Voloch. In order to do this, we state and prove a slightly more refined version of a special case of his result.
相似文献
22.
The rate constant kir for quenching diaryl ketone triplet states by electron poor olefins in CCl4 at room temperature decreases with decreasing reduction potential of the olefin. Unlike in previous cases, our data here fit the Weller equation, which predicts that en kir ≈ 1/RT. 相似文献
23.
We study shear-free spherically symmetric relativistic models with heat flow. Our analysis is based on Lie’s theory of extended
groups applied to the governing field equations. In particular, we generate a five-parameter family of transformations which
enables us to map existing solutions to new solutions. All known solutions of Einstein equations with heat flow can therefore
produce infinite families of new solutions. In addition, we provide two new classes of solutions utilising the Lie infinitesimal
generators. These solutions generate an infinite class of solutions given any one of the two unknown metric functions. 相似文献
25.
Pierpaolo D'Urso Livia De Giovanni Elizabeth Ann Maharaj Riccardo Massari 《Journal of Chemometrics》2014,28(1):28-51
Following a nonparametric approach, we suggest a time‐series clustering method. Our clustering approach combines the benefits connected to the interpretative power of the nonparametric representation of the time series, and the clustering and vector quantization informational gain produced by the adopted unsupervised neural networks technique, enhanced with the self‐organizing maps ordering and topological preservation abilities. The proposed clustering method takes into account a composite wavelet‐based information of the multivariate time series by adding to the information connected to the wavelet variance, namely the influence of variability of individual univariate components of the multivariate time series across scales, the information associated to wavelet correlation, represented by the interaction between pairs of univariate components of the multivariate time series at each scale, and then suitably tuning the combination of these pieces of information. In order to assess the effectiveness of the proposed clustering approach, a simulation study and an empirical application are shown. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
26.
We give the general solution of Liouville's equation in Robertson-Walker space-times, and use this to find exact inhomogeneous Einstein-Liouville solutions, using the covariant harmonic method of Ellis, Matravers and Treciokas [1]. The average four-velocity of the gas is tilted, and the gas has nonzero acceleration, shear, energy flux, and anisotropic stress. 相似文献
27.
In this paper, the temperature distribution at the surface of an infinite yawed wedge, when temperature of the main-stream is constant, is studied under two cases; one when temperature gradient of the wall is steady and the velocity of the main-stream is unsteady, and the other when temperature gradient of the wall is unsteady and the velocity of the main-stream is steady. It is found that the heat transfer depends on the wedge angle, the angle parameter and the yaw of the wedge. The behaviour with these parameters are studied and are illustrated graphically. 相似文献
28.
A. M. Msomi K. S. Govinder S. D. Maharaj 《International Journal of Theoretical Physics》2012,51(4):1290-1299
We consider a radiating shear-free spherically symmetric metric in higher dimensions. Several new solutions to the Einstein’s
equations are found systematically using the method of Lie analysis of differential equations. Using the five Lie point symmetries
of the fundamental field equation, we obtain either an implicit solution or we can reduce the governing equations to a Riccati
equation. We show that known solutions of the Einstein equations can produce infinite families of new solutions. Earlier results
in four dimensions are shown to be special cases of our generalised results. 相似文献
29.
The equation is the charged generalization of the Emden-Fowler equation that is crucial in the study of spherically symmetric shear-free spacetimes. This version arises from the Einstein–Maxwell system for a charged shear-free matter distribution. We integrate this equation and find a new first integral. For this solution to exist, two integral equations arise as integrability conditions. The integrability conditions can be transformed to nonlinear differential equations, which give explicit forms for and in terms of elementary and special functions. The explicit forms and arise as repeated roots of a fourth order polynomial. This is a new solution to the Einstein-Maxwell equations. Our result complements earlier work in neutral and charged matter showing that the complexity of a charged self-gravitating fluid is connected to the existence of a first integral. 相似文献
30.
An ansatz is developed to obtain interior solutions of the Einstein field equations for anisotropic spheres. This procedure necessitates a choice for the energy-density and the radial pressure. A class of solutions for a uniform energy-density source is presented. These anisotropic spheres match smoothly to the Schwarzschild exterior and are well-behaved in the interior of the sphere. 相似文献