# 4.7 Java1491-2d fourier transforms using java, part 2  (Page 15/21)

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## A different plotting color scheme

Note that the plotting color scheme that I used for Figure 7 is different from any of the plots previously shown in this module. This color scheme is whatI refer to as the Color Contour scheme in the module titled Plotting 3D Surfaces using Java .

This scheme quantizes the range from the lowest to the highest elevation into 23 levels, coloring the lowest elevation black, the highest elevation white, andassigning very specific colors to the 21 levels in between. The colors and the levels that they represent are shown in the calibration scales under the plotsin Figure 7 . The lowest elevation is on the left end of the calibration scale. The highest elevation is on the right end of the calibration scale.

## The amplitude spectrum

As before, the wavenumber amplitude spectrum with the origin in the top-left corner is shown in the top-right image in Figure 7 . The amplitude spectrum with the origin shifted to the center is shown in the lower right image in Figure 7 .

If you were to use the calibration scale to convert the colors along the horizontal and vertical axes in the lower right image into numeric values, youwould find that they approximate a rectified sin(x)/x shape as expected.

## The output surface

The output surface produced by performing an inverse Fourier transform on the complex wavenumber spectrum is shown in the lower-left image in Figure 7 . This surface appears to match the input surface shown in the top-left image in Figure 7 .

## The overall results

The numeric output for this case isn't very useful because none of the samples for which numeric data is provided fall within the square. However,because the real and imaginary parts exhibit the correct symmetry , , the shape of the amplitude spectrum is generally what we expect, and the output from the inverse Fouriertransform appears to match the original input causes us to conclude that the program is working properly in this case.

## Case 3

This case places a raised box at the top near the origin in the space domain, but the box is not on the diagonal as it was in Case 2.

(See the top-left image in Figure 8 for the new location of the box.)

Figure 8. Graphic output for Case 3.

## Amplitude spectrum should not change

As long as the size and the orientation of the box doesn't change, the wavenumber amplitude spectrum should be the same as Case 2 regardless of thelocation of the box in space. Since the size and orientation of this box is the same as in Case 2, the amplitude spectrum for this case should be the same asfor Case 2.

## The real and imaginary parts of the spectrum may change

However, the real and imaginary parts (or the phase) change as the location of the box changes relative to the origin in space.

## A hypothetical example

The purpose of this case is to illustrate a hypothetical example. If two different photographic images contain a picture of the same object in the samesize and the same orientation in space, that object will contribute the same values to the amplitude spectrum of both images regardless of where the objectis located in the different images.

anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
how did you get the value of 2000N.What calculations are needed to arrive at it
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