Representation of Vector Fields in Two and Three Dimensions Using Low-Degree Polynomials

Author(s):  
Giorgio Figliolini ◽  
Jorge Angeles

The subject of this paper is the formulation of a specific algorithm for the kinematic analysis of spherical four-bar linkages via the inflection spherical cubic and spherical Thales ellipse by devoting particular attention to the crossed four-bar linkage (anti-parallelogram). Moreover, both the inflection and the elliptic cones, which represent the equivalent of the Bresse cylinders of the planar case in three-dimensions, are obtained by showing the particular properties of the spherical motion in terms of the curvature of a coupler curve and both the velocity and acceleration vector fields. Of special interest are also the cases in which the three acceleration poles coincide at one unique point or in two plus one, which depends on the intersections of two spherical curves of third and second degree.


1999 ◽  
Vol 14 (09) ◽  
pp. 1345-1356 ◽  
Author(s):  
ALFREDO HERRERA-AGUILAR ◽  
OLEG KECHKIN

We present a simple algorithm to obtain solutions that generalize the Israel–Wilson–Perjés class for the low energy limit of heterotic string theory toroidally compactified from D=d+3 to three dimensions. A remarkable map existing between the Einstein–Maxwell (EM) theory and the theory under consideration allows us to solve directly the equations of motion making use of the matrix Ernst potentials connected with the coset matrix of heterotic string theory.1 For the particular case d=1 (if we put n=6, the resulting theory can be considered as the bosonic part of the action of D=4, N=4 supergravity) we obtain explicitly a dyonic solution in terms of one real 2×2-matrix harmonic function and 2n real constants (n being the number of Abelian vector fields). By studying the asymptotic behavior of the field configurations we define the charges of the system. They satisfy the Bogomol'nyi–Prasad–Sommerfield (BPS) bound.


2021 ◽  
Vol 29 (3) ◽  
pp. 75-89
Author(s):  
C. Brown ◽  
S. Pumplün

Abstract Let S be a domain and R = S[t; σ, δ] a skew polynomial ring, where σ is an injective endomorphism of S and δ a left σ -derivation. We give criteria for skew polynomials f ∈ R of degree less or equal to four to be irreducible. We apply them to low degree polynomials in quantized Weyl algebras and the quantum planes. We also consider f(t) = tm − a ∈ R.


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