1,720,987 research outputs found
On k-symmetries of hyperbolic spaces
No full textWe determine all the possible pointwise k-symmetric spaces of negative constant curvature. In general, such spaces are not k-symmetric.In fact we show that, for all n ≥ 3, k ≠ 2, H n is not k-symmetric, i.e., for any set of selected k-symmetries, one for each point of H n, the regularity condition does not hold
Dilatation Spaces
No full textRepresentation of dilatation spaces by means of two-sided incidence quasigroups. Dilatation spaces embedded into projective spaces and kinematic spaces
Finite loops arising from projective 3-space
No full textBy means of the method of transversals and sections we build up (left) loops (L, ∗) contained in the group G where G= PGL 2(q) or G= PSL 2(q) , q> 3 odd. Since such groups can be embedded in PG (3 , q) , the subgroups we considered for the construction of (L, ∗) are geometrically relevant (lines or planes of PG (3 , q)) or algebraically relevant (maximal subgroups)
Collineations of Geometric Structures Derived from Quaternion Algebras
No full textDetermination of the automorphisms of a kinematic space derived from a general quaternion algebr
Hyperstructures and Linear Spaces with Parallelism
No full textWe define a new class of hyperstructures called 'double hypergroupoids' suitable to describe incidence spaces with parallelism and relate geometrical configurations to algebraic properties. © 1992 Kluwer Academic Publishers
On k-symmetries of hyperbolic spaces
No full textWe determine all the possible pointwise k-symmetric spaces of negative constant curvature.
In general, such spaces are not k-symmetric.
In fact we show that, for all n>= 3, k not 2, H^n is not k-symmetric, i.e., for any set of selected k-symmetries, one for each point of H^n, the regularity condition does not hold
Output‐Only Modal Identification of Ancient L'Aquila City Hall and Civic Tower
No full textThe ancient masonry city hall in L'Aquila, Italy (Margherita Palace) that was severely damaged during the L'Aquila earthquake in April 2009 has been subjected to ambient vibration tests to determine its dynamic characteristics such as the natural frequencies, mode shapes, and damping ratios. The processing of ambient vibration responses is performed with three output-only identification approaches: (1) the frequency-domain decomposition, (2) random decrement (RD) technique combined with the eigensystem realization algorithm (ERA), and (3) the natural excitation technique (NExT) combined with ERA. Measurements were made in the palace and in the civic tower using 15 sensors in three different configurations, and the ambient vibration tests involved the simultaneous measurements of longitudinal and lateral vibrations. Lateral vibration modes for the civic tower were identified clearly; a total of five modal shapes and frequencies were identified in the frequency range 0 to 7 Hz. The modal identification in the palace was more difficult because of the severe damage; however, the two bending modes in the perpendicular directions were identified. The comparison of the three experimental techniques shows good agreement, confirming the reliability of the three identification methods. The results of the modal identification have been used to update the finite-element model of the palac
A class of fibered loops related to general hyperbolic planes
No full textIn this paper we introduce a class of left conjugacy closed loops which are also fibered in subsemigroups. We inspect the possibility to extend the semigroups of the fibration to commutative subgroups. Then we construct an example of such loops arising from a suitable selected subset of the set of all limit rotations of the hyperbolic plane over an euclidean field
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