Help


[permalink] [id link]
+
Page "X-ray crystallography" ¶ 181
from Wikipedia
Edit
Promote Demote Fragment Fix

Some Related Sentences

Picturebook and .
According to the Children's Picturebook Price Guide, 2006-2007 edition, The first edition Cat In The Hat has an estimated market value of $ 4000.
* Zielinski, Linda & Stan ; " Children's Picturebook Price Guide ", Chap.
* Virology. net Picturebook: Monkeypox
* Dr. Michael Flach, Corina Haase, MADAGASIKARA-Insel meiner Traeume, Exclusivefotografy, 11 / 2007, 208 pages, Picturebook, ISBN 978-3-935971-40-9, Madagaskar in pictures-Exclusivefotografy

Fourier and Transforms
* Many other forms of spectroscopy also rely upon Fourier Transforms to determine the three-dimensional structure and / or identity of the sample being analyzed, including Infrared and Nuclear Magnetic Resonance spectroscopies.
* Perl script to decode a wav file in KCS format to a text file using Fast Fourier Transforms
Filterbank strategies use Fast Fourier Transforms to divide the signal into different frequency bands.
One can show that if is infinitely differentiable, then the numerical algorithm using Fast Fourier Transforms will converge faster than any polynomial in the grid size h. That is, for any n > 0, there is a < math > C <
* Encyclopedia of Applied Physics Fourier and Other Mathematical Transforms 1997
* HP-71B — Handheld model natively programmable in an extended BASIC language including a RAM-based filesystem, recursion, multiline user-defined functions and subprogram calling with parameter passing, but also capable of accepting plug-in ROM modules to provide such functionalities as full I / O capabilities to any type of device ( printers, mass storage, measurement instruments ), programmability in other languages ( Forth, Assembler ), advanced math capabilities ( such as matrix operations, support for complex numbers, multidimensional numerical integration and root finding, Fast Fourier Transforms, etc.
In 1971, they published their research in a paper (“ Three dimensional reconstructions from radiographs and electron micrographs: Application of convolution instead of Fourier Transforms ,” Proc.
These surveys required intensive use of inverse Fourier Transforms, and were made possible by development of a new generation of computers such as the Titan.
One of Titan's most intensive uses was to compute the inverse Fourier Transforms of data from the One-Mile Radio Telescope.
Fast Fourier Transforms are used throughout the CASTEP code, as is the Ewald summation method for Coulombic energies.

Fourier and illustrating
In the figure above, illustrating the Fourier transforming property of lenses, the lens is in the near field of the object plane transparency, therefore the object plane field at the lens may be regarded as a superposition of plane waves, each one of which propagates at some angle with respect to the z-axis.

Fourier and relationship
# compute the instantaneous frequency / amplitude relationship of the signal using the STFT, which is the discrete Fourier transform of a short, overlapping and smoothly windowed block of samples ;
The Fourier inversion theorem details this relationship.
It is more convenient in a linear system to take the Fourier transform and write this relationship as a function of frequency.
* Coherent sampling, a relationship used in Fast Fourier transforms
This plane wave spectrum representation of the electromagnetic field is the basic foundation of Fourier Optics ( this point cannot be emphasized strongly enough ), because when z = 0, the equation above simply becomes a Fourier transform ( FT ) relationship between the field and its plane wave content ( hence the name, " Fourier optics ").
In this case, P is a convolution of the impulse response susceptibility χ and the electric field E. Such a convolution takes on a simpler form in the frequency domain — by Fourier transforming the relationship and applying the convolution theorem, one obtains the following relation for a linear time-invariant medium:

Fourier and between
Relationship between the ( continuous ) Fourier transform and the discrete Fourier transform.
Fourier series can be conveniently studied in the context of Hilbert spaces, which provides a connection between harmonic analysis and functional analysis.
Mathematically, the uncertainty relation between position and momentum arises because the expressions of the wavefunction in the two corresponding bases are Fourier transforms of one another ( i. e., position and momentum are conjugate variables ).
A similar tradeoff between the variances of Fourier conjugates arises wherever Fourier analysis is needed, for example in sound waves.
There is an intimate connection between power series and Fourier series.
There is a close connection between the definition of Fourier series and the Fourier transform for functions ƒ which are zero outside of an interval.
Additionally, the phase correlation uses the fast Fourier transform to compute the cross-correlation between the two images, generally resulting in large performance gains.
There is a direct correspondence between the filter's frequency function and its impulse response: the former is the Fourier transform of the latter.
In addition to his writings on anarchism and Temporary Autonomous Zones, Bey has written essays on such diverse topics as Tong traditions, the utopian Charles Fourier, the fascist Gabriele D ' Annunzio, alleged connections between Sufism and ancient Celtic culture, technology and Luddism, Amanita muscaria use in ancient Ireland, and sacred pederasty in the Sufi tradition.
Another significant related point is that the Langlands approach stands apart from the whole development triggered by monstrous moonshine ( connections between elliptic modular functions as Fourier series, and the group representations of the Monster group and other sporadic groups ).
Typically one finds simple relations describing the antenna far field patterns, often involving trigonometric functions or at worst Fourier or Hankel transform relationships between the antenna current distributions and the observed far field patterns.
In 1898 J. Willard Gibbs published a short note in which he considered what today would be called a sawtooth wave and pointed out the important distinction between the limit of the graphs of the partial sums of the Fourier series, and the graph of the function that is the limit of those partial sums.
In homogeneous systems it is often desirable to transform between real space an the momentum representations, hence, the quantum fields operators in Fourier basis yields:
The Poisson summation formula similarly provides a connection between Fourier analysis on Euclidean spaces and on the tori of the corresponding dimensions.
For Fourier transform purposes, sampling is modeled as a product between s ( t ) and a Dirac comb function.
For complexcoefficients, there is no difference between such a function and a finite Fourier series.
Fourier transform switches between functions on a vector space and its dual:
In physics, the canonical commutation relation is the relation between canonical conjugate quantities ( quantities which are related by definition such that one is the Fourier transform of another ), for example:

Fourier and crystal
The advantages of electron diffraction over X-ray crystallography are that the specimen need not be a single crystal or even a polycrystalline powder, and also that the Fourier transform reconstruction of the object's magnified structure occurs physically and thus avoids the need for solving the phase problem faced by the X-ray crystallographers after obtaining their X-ray diffraction patterns of a single crystal or polycrystalline powder.
The two-dimensional images taken at different rotations are converted into a three-dimensional model of the density of electrons within the crystal using the mathematical method of Fourier transforms, combined with chemical data known for the sample.
As derived below, the electron density within the crystal and the diffraction patterns are related by a simple mathematical method, the Fourier transform, which allows the density to be calculated relatively easily from the patterns.
One image of spots is insufficient to reconstruct the whole crystal ; it represents only a small slice of the full Fourier transform.
The recorded series of two-dimensional diffraction patterns, each corresponding to a different crystal orientation, is converted into a three-dimensional model of the electron density ; the conversion uses the mathematical technique of Fourier transforms, which is explained below.
This symmetry allows one to measure the full Fourier transform from only half the reciprocal space, e. g., by rotating the crystal slightly more than 180 ° instead of a full 360 ° revolution.
Therefore, to obtain a full set of Fourier transform data, it is necessary to rotate the crystal through slightly more than 180 °, or sometimes less if sufficient symmetry is present.

0.914 seconds.