# 4.6 Java1490-2d fourier transforms using java, part 1  (Page 14/15)

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Because of the shorter wavelengths involved, typical radar sensors are usually small enough that they can be physically turned and tilted. Thus, it isnot unusual to see radar sensors turning around and tilting up and down. Although I'm not personally aware of any applications that use arrays of radarsensors, my suspicion is that there probably are some being used in fixed air surveillance operations.

## Petroleum exploration

A large percentage of petroleum exploration involves the insertion of a powerful surge of acoustic energy into the ground (or into the ocean) and listening for and recording the echo signals returned by the various layers ofthe earth. By moving across the earth and repeating this process, a profile of the earth's layering can be produced. An experienced exploration geophysicist can examine the profiles and reach conclusions as to the likelihoodthat a particular stratum contains petroleum.

Exploration geophysicists have been using arrays of sensors for this purpose for at least the past 55 years according to my personal knowledge, and probablyfor many years before that.

## Image processing in the wavenumber domain

While the examples described above are interesting, they are beyond the scope of anything that I can demonstrate online. However, there are severalinteresting applications using 2D Fourier transforms that I can demonstrate online. One of those applications is image processing.

Future modules will show how to use 2D Fourier transforms for such purposes as softening images, sharpening images, doing edge detection on images, etc. Forthis application, it is satisfactory to use a 2D Fourier transform program that assumes that the space domain data is purely real. Therefore, the program that Iwill present and explain in Part 2 of this module will make that assumption.

## Image processing in the space domain

The 2D Fourier transform will be used in future modules to help explain how and why 2D image convolution behaves the way it does. A preview of that materialis shown in Figure 6 .

Figure 6. Image processing in the space domain.

## Convolution versus multiplication

Convolution in the space domain is equivalent to multiplication in the wavenumber domain, and vice versa.

## A simple space function and its wavenumber spectrum

The top left image in Figure 6 shows a simple 3D surface in space consisting of a raised square. The wavenumber spectrum of that surface is shown in thelower left image in Figure 6 . Note that the spectrum has a peak at a wavenumber value of zero with low values at the higher wave numbers near the edges. Thepeak in the center is relatively narrow with respect to the folding wave number at the edges.

## A 2D convolution operator and its spectral response

The image in the upper center of Figure 6 shows a typical 2D convolution operator consisting of a value of +8 in the center surrounded by eightcoefficients each having a value of -1.

The wavenumber spectral response of that convolution operator is shown in the lower center. Note that it has peaks at the folding wavenumbers on all foursides with a low value in the center.

how do they get the third part x = (32)5/4
can someone help me with some logarithmic and exponential equations.
20/(×-6^2)
Salomon
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
Salomon
I'm not sure why it wrote it the other way
Salomon
I got X =-6
Salomon
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
Commplementary angles
hello
Sherica
im all ears I need to learn
Sherica
right! what he said ⤴⤴⤴
Tamia
hii
Uday
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
a perfect square v²+2v+_
kkk nice
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
or infinite solutions?
Kim
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Al
y=10×
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
rolling four fair dice and getting an even number an all four dice
Kristine 2*2*2=8
Differences Between Laspeyres and Paasche Indices
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
is it 3×y ?
J, combine like terms 7x-4y
how do you translate this in Algebraic Expressions
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
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.
what is nano technology
what is system testing?
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
what is system testing
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
how did you get the value of 2000N.What calculations are needed to arrive at it
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