X-Nico

unusual facts about discrete-time Fourier transform



Alan Pritsker

During the early 1970s, he and his students formulated the basic principles of combined discrete-continuous simulation and implemented those principles in the GASP IV, SAINT, and SMOOTH simulation languages.

Bilinear transformation

Bilinear transform (Signal Processing), used to transform continuous time signal to discrete time

Binomial QMF

The binomial QMF bank with perfect reconstruction (PR) was designed by Ali Akansu, et al. published in 1990, using the family of binomial polynomials for subband decomposition of discrete-time signals.

Bruno Putzeys

Current activities include designing high-performance discrete AD/DA converters and analogue signal processing circuits, DSP algorithms, class D power amplifiers and switch-mode power supplies.

Bucket-brigade device

Despite being analog in their representation of individual signal voltage samples, these devices are discrete in the time domain and thus are limited by the Nyquist–Shannon sampling theorem; both the input and output signals are generally low-pass filtered.

Countertop

The "unfitted" kitchen design style exemplified by Johnny Grey may also include detached and/or varied countertop surfaces mounted on discrete base support structures.

Cylindrical harmonics

It can be seen that the Z(k,z) functions are the kernels of the Fourier transform or Laplace transform of the Z(z) function and so k may be a discrete variable for periodic boundary conditions, or it may be a continuous variable for non-periodic boundary conditions.

Danubian endemic familial nephropathy

It was first identified in the 1920s among several small, discrete communities along the Danube River and its major tributaries, in the modern countries of Croatia, Bosnia and Herzegovina, Serbia, Romania and Bulgaria.

DHT

Discrete Hartley transform, a Fourier-related transform of discrete, periodic data similar to the discrete Fourier transform

DIMACS

The Center for Discrete Mathematics and Theoretical Computer Science (DIMACS) is a collaboration between Rutgers University, Princeton University, and the research firms AT&T, Bell Labs, Applied Communication Sciences, and NEC.

Discrete logarithm records

On 18 Jun 2005, Antoine Joux and Reynald Lercier announced the computation of a discrete logarithm modulo a 130-digit (431-bit) strong prime in three weeks, using a 1.15 GHz 16-processor HP AlphaServer GS1280 computer and a number field sieve algorithm.

Discrete measure

The simplest example of a discrete measure on the real line is the Dirac delta function \delta.

Discrete transform

For example, the discrete-time Fourier transform and the Z-transform, from discrete time to continuous frequency, and the Fourier series, from continuous time to discrete frequency, are outside the class of discrete transforms.

Downsampling

The abscissa of the top pair of graphs represents the discrete-time Fourier transform (DTFT), which is a Fourier series representation of a periodic summation of X(f):

Electric potential energy

Using Coulomb's law, it is known that the electrostatic force F and the electric field E created by a discrete point charge Q are radially directed from Q.

FM broadcasting

In 1969 Louis Dorren invented the Quadraplex system of single station, discrete, compatible four-channel FM broadcasting.

Fractional Fourier transform

The discrete fractional Fourier transform is defined by Zeev Zalevsky in

Frank Ruskey

His research involves algorithms for exhaustively listing discrete structures, combinatorial Gray codes, Venn and Euler diagrams, combinatorics on words, and enumerative combinatorics.

Functional group

The International Union of Crystallography in its Crystallographic Information File dictionary defines "moiety" to represent discrete non-bonded components.

George Mostow

Roger Howe, editor, Discrete groups in geometry and analysis.

Gerald Teschl

with Fritz Gesztesy, Helge Holden and Johanna Michor: Soliton Equations and their Algebro-Geometric Solutions, Volume 2 (1+1 dimensional discrete models), Cambridge Studies in Advanced Mathematics Bd.114, Cambridge University Press 2008, ISBN 978-0-521-75308-1

H.264/MPEG-4 AVC

This design is conceptually similar to that of the well-known discrete cosine transform (DCT), introduced in 1974 by N. Ahmed, T.Natarajan and K.R.Rao, which is Citation 1 in Discrete cosine transform.

Hann function

The Hann function, named after the Austrian meteorologist Julius von Hann, is a discrete window function given by

Hawaii Ocean Time-series

These strategies include high resolution conductivity-temperature-depth (CTD) profiles, biogeochemical analyses of discrete water samples, in situ vertically profiling bio-optical instrumentation, free-drifting arrays for determinations of primary production and particle fluxes, deep ocean sediment traps, and oblique plankton net tows.

Hexagonal sampling

Russell M. Mersereau developed hexagonal discrete Fourier transform (DFT) and hexagonal finite extent impulse response filters.

Hybrid computer

Signals pass across the synapses from one nerve cell to the next as discrete (digital) packets of chemicals, which are then summed within the nerve cell in an analog fashion by building an electro-chemical potential until its threshold is reached, whereupon it discharges and sends out a series of digital packets to the next nerve cell.

Hyperkinesia

Chorea is a continuous, random-appearing sequence of one or more discrete involuntary movements or movement fragments.

Kell factor

The Kell factor, named after RCA engineer Raymond D. Kell, is a parameter used to limit the bandwidth of a sampled image signal to avoid the appearance of beat frequency patterns when displaying the image in a discrete display devices, usually taken to be 0.7.

Kon Tum

Among the town's landmarks, there is a Roman Catholic wooden church on discrete stilts and a large French-built seminary which hosts a small museum on local hill tribes.

Logistic model

Logistic map – a discrete version, which exhibits chaotic behavior

Loop-erased random walk

The number of domino tilings of a graph can be calculated using the determinant of special matrices, which allow to connect it to the discrete Green function which is approximately conformally invariant.

Mass function

Probability mass function, a function that gives the probability that a discrete random variable is exactly equal to some value

McGill University School of Computer Science

David Avis - discrete optimization and computational geometry

Mobile PCI Express Module

Most Acer Core 2 Duo era notebooks with discrete graphics cards support MXM.

Multitaper

These are given by the Slepian sequences, after David Slepian (also known in literature as discrete prolate spheroidal sequences or DPSS for short) with parameter W and orders k = 0 to K − 1.

Nandalal Bose

Like Raphael Nandalal was a great synthesizer, his originality lay in his ability to marshal discrete ideas drawn from Abanindranath Tagore, Rabindranath Tagore, E. B. Havell, Ananda Coomaraswamy, Okakura Kakuzo and Mahatma Gandhi into a unique and unified programme for the creation of a new art movement in India.

Natura non facit saltus

However, as the basic structure of DNA is discrete, nature is now widely understood to make jumps at the biological level, if only on a very small scale.

Networked narrative

A networked narrative, also known as a network narrative or distributed narrative, is a narrative partitioned across a network of interconnected authors, access points, and/or discrete threads.

Oriented matroid

Richter-Gebert, J. and G. Ziegler, Oriented Matroids, In Handbook of Discrete and Computational Geometry, J. Goodman and J.O'Rourke, (eds.), CRC Press, Boca Raton, 1997, p.

Regina Tyshkevich

An international conference "Discrete Mathematics, Algebra, and their Applications", sponsored by the Central European Initiative, was held in Minsk, Belarus, October 2009 in honor of her 80th birthday.

Scientific calculator

The HP-9100 series was built entirely from discrete transistor logic with no integrated circuits, and was one of the first uses of the CORDIC algorithm for trigonometric computation in a personal computing device, as well as the first calculator based on Reverse Polish Notation (RPN) entry.

Sol-gel

The volume change at the transition point is either discrete (as in a first-order Ehrenfest transition) or continuous (second order Ehrenfest analogy), depending on the degree of ionization of the gel and on the solvent composition.

Specimen Days

The novel is divided into what are essentially three discrete short stories, unified by common threads such as character names and types, story location (New York City), story themes (such as shared humanity), and the presence of Walt Whitman (whether through actual physical presence, quotation of his works via narrator or character, or the spirit of his ideas expressed through narrator or character).

Stéphane Mallat

Specifically, he collaborated with Yves Meyer to develop the Multiresolution Analysis (MRA) construction for compactly supported wavelets, which made the implementation of wavelets practical for engineering applications by demonstrating the equivalence of wavelet bases and conjugate mirror filters used in discrete, multirate filter banks in signal processing.

Topological defect

Domain walls, two-dimensional membranes that form when a discrete symmetry is broken at a phase transition.

Universal Turing machine

Davis makes a persuasive argument that Turing's conception of what is now known as "the stored-program computer", of placing the "action table"—the instructions for the machine—in the same "memory" as the input data, strongly influenced John von Neumann's conception of the first American discrete-symbol (as opposed to analog) computer—the EDVAC.

Václav Chvátal

he studied a weighted version of the set cover problem, and proved that a greedy algorithm provides good approximations to the optimal solution, generalizing previous unweighted results by David S. Johnson (J. Comp. Sys. Sci. 1974) and László Lovász (Discrete Math. 1975).

Veech surface

In mathematics, a Veech surface is a translation surface (X,ω) (a Riemann surface X with a holomorphic 1-form ω) whose group SL(X,ω) of affine diffeomorphisms is a lattice in SL2(R) (a discrete subgroup of cofinite volume).

Vincent Lafforgue

Lafforgue was awarded the 2000 EMS Prize for his contribution to the K-theory of operator algebras: the proof of the Baum–Connes conjecture for discrete co-compact subgroups of SL(3,\mathbb{R}),SL(3,\mathbb{C}), SL(3,\mathbb{Q} p) and some other locally compact group (and of more general objects).


see also