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Comparison between the performances of a linear isolator and an isolator with a geometrically nonlinear damper /Carranza López, José Camilo. January 2013 (has links)
Orientador: Michael John Brennan / Banca: Gilberto Pechoto de Melo / Banca: Paulo Jose Paupitz Gonçalves / Resumo: Nesta dissertação investiga-se o comportamento de um sistema de isolamento de vibrações de um grau de liberdade com amortecimento não linear. As transmissibilidades das forças e de movimento deste sistema são comparadas com as de um sistema de isolamento de vibrações linear. O sistema não linear é composto por uma mola e um amortecedor viscoso, ambos lineares, que estão acoplados a uma massa de modo tal que o amortecedor é perpendicular à mola. O sistema é excitado harmonicamente por um deslocamento da base ou por uma força na direção da mola. Quando o sistema é excitado por uma forca harmônica, as forças transmitidas através da mola e do amortecedor são analisadas separadamente, decompondo-as em termos dos seus harmônicos; permitindo assim determinar a contribuição individual de cada elemento no comportamento não linear do sistema como um todo. A transmissibilidade do sistema de isolamento não linear é calculada por meio de expressões analíticas validas para excitações com pequenas amplitudes, já para excitações com amplitudes grandes, calcula-se por meio de simulações numéricas. / Abstract: In this work the behaviour of a single degree of freedom (SDOF) passive vibration isolation system with a geometrically nonlinear damper is investigated, and its displacement and force transmissibilities are compared with that of a linear system. The nonlinear system is composed of a linear spring and a linear viscous damper which are connected to a mass so that the damper is perpendicular to the spring. The system is excited with either a harmonic force or an imposed displacement of the base in the direction of the spring. When excited with a harmonic force, the forces transmitted through the spring and the damper are analysed separately by decomposing the forces in terms of their harmonics. This enables the effects of these elements to be studied and to determine how they contribute individually to the nonlinear behaviour of the system as a whole. The transmissibilities of the nonlinear isolation system are calculated using analytical expressions for small amplitudes of excitation and by using numerical simulations for high amplitudes of excitation. / Mestre
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An Introduction to the Winograd Discrete Fourier TransformAgnello, Janice S. 01 April 1979 (has links) (PDF)
This paper illustrates Winograd's approach to computing the Discrete Fourier Transform (DFT). This new approach changes the DFT into a cyclic convolution of 2 sequences, and illustrates shortcuts for computing this cyclic convolution. This method is known to reduce the number of multiplies required to about 20% less than the number of multiplies used by the techniques of the Fast Fourier Transform. Three approaches are discussed, one for prime numbers, one for products of primes, and lastly one for powers of odd primes. For powers of 2 Winograd's algorithm is, in general, inefficient and best if it is not used. A computer simulation is illustrated for the 35 point transform and its execution time is compared with that of the Fast Fourier Transform algorithm for 32 points.
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A problem in depleted fourier seriesGreer, Edison. January 1938 (has links)
Call number: LD2668 .T4 1938 G71
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Fundamental concepts on Fourier Analysis (with exercises and applications)Dixit, Akriti January 1900 (has links)
Master of Science / Department of Mathematics / Diego M. Maldonado / In this work we present the main concepts of Fourier Analysis (such as Fourier series,
Fourier transforms, Parseval and Plancherel identities, correlation, and convolution) and
illustrate them by means of examples and applications. Most of the concepts presented
here can be found in the book "A First Course in Fourier Analysis" by David W.Kammler.
Similarly, the examples correspond to over 15 problems posed in the same book which have
been completely worked out in this report. As applications, we include Fourier's original
approach to the heat flow using Fourier series and an application to filtering one-dimensional
signals.
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Colour object recognition using a complex colour representation and the frequency domainThornton, A. L. January 1998 (has links)
No description available.
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Model-based feature extraction and classification for automatic face recognitionBenn, David E. January 2000 (has links)
No description available.
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Combined Fourier techniquesAlston, D. January 1988 (has links)
No description available.
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High speed output interface for a multifrequency quaternary phase shift keying signal generated on an industry standard computerChilds, Robert Daniel. 12 1900 (has links)
Approved for public release; distribution is unlimited / A multiple frequency quaternary phase shift keyed signal
is generated using a complex Fast Fourier Transform on an
industry standard personal computer and is output using direct
memory access through a digital to analog converter. The
output is permitted at rates of up to the maximum direct
memory access rate of the computer. An assembly language
program loop, direct hardware output, and high level language
output are compared as alternate solutions to the problem of
outputting a data stream contained in the computer primary
memory. / http://archive.org/details/highspeedoutputi00chil / Lieutenant, United States Navy
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The Gibbs’ phenomenon for Fourier–Bessel seriesFay, TH, Kloppers, PH 01 January 2003 (has links)
Summary
The paper investigates the Gibbs’ phenomenon at a jump discontinuity for
Fourier–Bessel series expansions. The unexpected thing is that the Gibbs’
constant for Fourier–Bessel series appears to be the same as that for Fourier
series expansions. In order to compute the coefficients for Fourier–Bessel
functionsefficiently, several integral formulasare derived and the Struve
functions and their asymptotic expansions discussed, all of which significantly
ease the computations. Three numerical examples are investigated. Findings
suggest further investigations suitable for undergraduate research projects or
small student group investigations.
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Classroom notes: Summing sequences having mixed signsFay, TH, Walls, GL 11 June 2003 (has links)
Summary
A result is discussed which permits the summing of series whose terms have
more complicated sign patterns than simply alternating plus and minus. The
Alternating Series Test, commonly taught in beginning calculus courses, is a corollary. This result, which is not difficult to prove, widens the series summable
by beginning students and paves the way for understanding more advanced
questions such as convergence of Fourier series. An elementary exposition is
given of Dirichlet’s Test for the convergence of a series and an elementary
example suitable for a beginning calculus class and a more advanced example
involving a Fourier series which is appropriate for an advanced calculus class
are provided. Finally, two examples are discussed for which Dirichlet’s Test
does not apply and a general procedure is given for deciding the convergence or
divergence of these and similar examples.
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