# 4.6 Java1490-2d fourier transforms using java, part 1  (Page 3/15)

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## The space domain

In this module, we will extend the concept of the Fourier transform from the time domain into the space domain. In making this extension, we will encountersome significant additional complexity. For example, while time is one-dimensional, space is three-dimensional. While you can only move forward andbackwards in time, you can move up, down, forward, backward, and from side to side in space.

(In order to keep the complexity of this module in check, we will assume that space is only two-dimensional, allowing movement up, down, andfrom side to side only. This will serve us well later for such tasks as image processing. Three-dimensional Fourier transforms are beyond the scopeof this module.)

It is also possible and very common to combine time domain signal processing with space domain signal processing. However, that also is beyond the scope ofthis module.

## Time and space are analogous

We will consider the space domain to be analogous to the time domain, with the stipulation that the space domain has two dimensions. The unit of measure inthe time domain is usually seconds, or some derivative thereof. The unit of measure in space is usually meters, or some derivative thereof.

As with the time domain, we will assume that all space domain surfaces are purely real (as opposed to being complex) . This will allow us to simplify our computations when performing the 2D Fourier transform to transformour data from the space domain into the wavenumber domain.

(I will point out that from a practical viewpoint this assumption is much more limiting in the space domain than in the time domain. Complexspace domain functions are quite common in such areas as antenna array processing.)

## Frequency and wavenumber are analogous

We will consider the wavenumber domain to be analogous to the frequency domain. The unit of measure in the frequency domain is cycle per second, or somederivative thereof. The unit of measure in the wavenumber domain is cycles per meter or some derivative thereof.

## Period and wavelength are analogous

The reciprocal of the typical unit of measure in the frequency domain is seconds per cycle, commonly referred to as the period. The reciprocal of thetypical unit of measure in the wavenumber domain is meters per cycle, commonly referred to as the wavelength.

## Some real world examples

With all of this as background, I will begin by discussing some real world engineering problems for which the solution lies in an understanding of thewavenumber domain. I will use these examples to show some of the practical uses of 2D Fourier transforms.

Following that (in Part 2 of this series) , I will present and explain a class that you can copy and use to perform 2D Fourier transforms. Then I will presentand explain a program that exercises and tests the 2D Fourier transform class for some common 3D surfaces.

## A commercial radio station

Assume that you have just acquired an FCC license to build and operate a new commercial radio station in a small town in west Texas. As is frequently thecase in west Texas, your town is situated at the intersection of two highways. One highway runs northeast and southwest. The other highway runs northwest andsouthwest. The two highways are generally perpendicular to one another. Like many highways in west Texas, each of these highways is straight as an arrow withvery few curves.

#### Questions & Answers

where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
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