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51.
Chris Monico 《代数通讯》2013,41(1):218-227
We cryptanalyze a recently proposed matrix-based MOR cryptosystem. The security of the system depends on the difficulty of solving the following discrete logarithm problem: given an inner automorphism φ of SL(d, 𝔽 q ) and φ a (each given in terms of their images on generators of SL(d, 𝔽 q )), find a. We show that this problem can be reduced to a small number of similar problems in quotients of polynomial rings and solved in subexponential-time. 相似文献
52.
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54.
Periodic review inventory models are widely used in practice, especially for inventory systems in which many different items are purchased from the same supplier. However, most of periodic review models have assumed a fixed length of the review periods. In practice, it is possible that the review periods are of a random (stochastic) length. This paper presents an inventory control model in the case of random review intervals and special sale offer from the supplier. The replenishment interval is assumed to obey from two different distributions, namely, exponential and uniform distributions. Also, shortages are allowed in the term of partial backordering. For this model, its convexity condition is discussed and closed form solutions are proposed. 相似文献
55.
Let K be a field of characteristic p > 0, let L be a restricted Lie algebra and let R be an associative K-algebra. It is shown that the various constructions in the literature of crossed product of R with u(L) are equivalent. We calculate explicit formulae relating the parameters involved and obtain a formula which hints at a noncommutative version of the Bell polynomials. 相似文献
56.
Saeid Azam 《代数通讯》2013,41(1):465-488
In 1985 K. Saito [Sal] introduced the concept of an extended affine Weyl group (EAWG), the Weyl group of an extended affine root system (EARS). In [A2, Section 5J, we gave a presentation called “a presentation by conjugation” for the class of EAWGs of index zero, a subclass of EAWGs. In this paper we will give a presentation wh.ich we call a “generalized present.ation by conjugation” for the class of reduced EAWGs. If the extended affine Weyl group is of index zero this presentation reduces to “a presentation by conjugation”. Our main result states that when the nullity of the EARS is 2, these two presentations coincide that is, EAWGs of nullity 2 have “a presentation by conjugation”. In [ST] another presentation for EAWGs of nullity 2 is given. 相似文献
57.
B.A. Mamedov 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(7):1277-1280
New analytical results are presented performing to cylindrical exponential integral (CEI) functions for integer and noninteger values of parameter n. These integrals are often employed of two-dimensional radiative transfer in an absorbing-emitting medium and determination of the radiative flux in cylindrical media. The simple and efficient algorithm for the calculation of these functions is developed. The series expansion relations established in this work are accurate enough in the whole range of parameters. 相似文献
58.
Anatoli Andrei Vankov 《Foundations of Physics》2008,38(6):523-545
In relativistic theories, the assumption of proper mass constancy generally holds. We study gravitational relativistic mechanics
of point particle in the novel approach of proper mass varying under Minkowski force action. The motivation and objective
of this work are twofold: first, to show how the gravitational force can be included in the Special Relativity Mechanics framework,
and, second, to investigate possible consequences of the revision of conventional proper mass concept (in particular, to clarify
a proper mass role in the divergence problem). It is shown that photon motion in the gravitational field can be treated in
terms of massless refracting medium, what makes the gravity phenomenon compatible with SR Mechanics framework in the variable
proper mass approach.
Specifically, the problem of point particle in the spherical symmetric stationary gravitational field is studied in SR-based
Mechanics, and equations of motion in the Lorentz covariant form are obtained in the relativistic Lagrangean problem formulation.
The dependence of proper mass on potential field strength is derived from the Euler-Lagrange equations as well. One of new
results is the elimination of conventional 1/r divergence, which is known to be not removable in Schwarzschild gravitomechanics. Predictions of particle and photon gravitational
properties are in agreement with GR classical tests under weak-field conditions; however, deviations rise with potential field
strength. The conclusion is made that the approach of field-dependent proper mass is perspective for development of SR gravitational
mechanics and further studies of gravitational problems. 相似文献
59.
Alexandre A. Martins Mario J. Pinheiro 《International Journal of Theoretical Physics》2008,47(10):2706-2715
We address the problem of inertial property of matter through analysis of the motion of an extended charged particle. Our
approach is based on the continuity equation for momentum (Newton’s second law) taking due account of the vector potential
and its convective derivative. We obtain a development in terms of retarded potentials allowing an intuitive physical interpretation
of its main terms. The inertial property of matter is then discussed in terms of a kind of induction law related to the extended
charged particle’s own vector potential. Moreover, it is obtained a force term that represents a drag force acting on the
charged particle when in motion relatively to its own vector potential field lines. The time rate of variation of the particle’s
vector potential leads to the acceleration inertia reaction force, equivalent to the Schott term responsible for the source
of the radiation field. We also show that the velocity dependent term of the particle’s vector potential is connected with
the relativistic increase of mass with velocity and generates a longitudinal stress force that is the source of electric field
lines deformation. In the framework of classical electrodynamics, we have shown that the electron mass has possibly a complete
electromagnetic origin and the obtained covariant equation solves the “4/3 mass paradox” for a spherical charge distribution. 相似文献
60.
H. Fakhri 《International Journal of Theoretical Physics》2008,47(10):2625-2634
The hierarchy of supersymmetric partner Schrödinger equations for the superpotentials Acot?θ and Btanh?y with A and B as half-integer and negative integer numbers are solved. The number of bound states for given trigonometric and hyperbolic potentials are infinite and finite, respectively. In addition to the spectrum-generating corresponding to the standard supersymmetry which is based on shifting potential parameter, there exist three other different methods for generating the spectrum. The first method is based on supersymmetrizing two given models via infinite and finite number of their bound states. This is realized by the ladder operators which shift only quantum numbers. The second and third methods are based on supersymmetrizing any of the models via all bound states corresponding to hierarchy of their partner potentials. They are respectively realized via simultaneous increasing or decreasing of quantum number and the potential parameter, and also, increasing one of them while decreasing the other. Any of the second and third methods leads to introducing two different classes of the algebraic solutions for both models. 相似文献