1,720,997 research outputs found
La bellezza di ciò che si desidera, si ama e si ricorda.
No full textIn Abrate M. Ed “Antinoo” La bellezza della diversità / la diversità nella bellezza.
Associazione Culturale Umanistica “All’ombra del Monviso”. Racconigi, 29 giugno 2013. ELLEDI – Arti grafiche Carmagnola
On the synthesis of Quantum Hall Array Resistance Standards
Full text linkQuantum Hall effect (QHE) is the basis of modern resistance metrology. In Quantum Hall Array Resistance Standards (QHARS), several individual QHE elements, each one having the same QHE resistance (typically half of the von Klitzing constant), are arranged in networks that realize resistance values close to decadic values (such as 1 kiloohm or 100 kiloohm), of direct interest for dissemination. The same decadic value can be approximated with different grades of precision, and even for the same approximation several networks of QHE elements can be conceived. The paper investigates the design of QHARS networks by giving methods to find a proper approximation of the resistance of interest, and to design the corresponding network with a small number of elements. Results for several decadic cases are given
Spiral tessellation of the sphere
Full text linkIn this paper we describe a tessellation of the unit sphere in the 3-dimensional space realized using a spiral joining the north and the south poles. This tiling yields to a one dimensional labeling of the tiles covering the whole sphere and to a 1-dimensional natural ordering on the set of tiles of the tessellation. The correspondence between a point on the sphere and the tile containing it is derived as an analytical function, allowing the direct computation of the tile. This tessellation exhibits some intrinsic features useful for general applications: absence of singular points and efficient tiles computation. Moreover, this tessellation can be parametrized to obtain additional features especially useful for spherical coordinate indexing: tiles with equal area and good shape uniformity of tiles. An application to spherical indexing of a database is presented, it shows an assessment of our spiral tiling for practical uses
Stability Analysis of Luenberger Observers for Speed Sensorless High Performance Spindle Drives
No full textImproved Luenberger Stator Flux Observer for High Speed Sensorless Induction Motor Drives
No full textWriting π as sum of arctangents with linear recurrent sequences, Golden mean and Lucas numbers
No full textIn this paper, we study the representation of π as sum of arctangents. In particular, we highlight the role of linear recurrent sequences obtaining new identities. Moreover, we provide a method in order to express π as sum of arctangents involving the Golden mean, the Lucas numbers, and more in general any quadratic irrationality. © World Scientific Publishing Company
Colored compositions, Invert operator and elegant compositions with the "black tie"
No full textThis paper shows how the study of colored compositions of integers reveals some unexpected and original connection with the Invert operator. The Invert operator becomes an important tool to solve the problem of directly counting the number of colored compositions for any coloration. The interesting consequences arising from this relationship also give an immediate and simple criterion to determine whether a sequence of integers counts the number of some colored compositions. Applications to Catalan and Fibonacci numbers naturally emerge, allowing to clearly answer to some open questions. Moreover, the definition of colored compositions with the "black tie" provides straightforward combinatorial proofs to a new identity involving multinomial coefficients and to a new closed formula for the Invert operator. Finally, colored compositions with the "black tie" give rise to a new combinatorial interpretation for the convolution operator, and to a new and easy method to count the number of parts of colored compositions. © 2014 Elsevier B.V. All rights reserved
Periodic representations for cubic irrationalities
No full textIn this paper we present some results related to the problem of finding periodic representations for algebraic numbers. In particular, we analyze the problem for cubic irrationalities. We show an interesting relationship between the convergents of bifurcating continued fractions related to a couple of cubic irrationalities, and a particular generalization of the Rédei polynomials. Moreover, we give a method to construct a periodic bifurcating continued fraction for any cubic root paired with another determined cubic root
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