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(By now, you may be suspecting that I have a particular affinity for a data length of 400 samples. If so, you are correct. This is not a technicalaffinity. Rather, it is a visual one. These figures are formatted such that the plotted data occupies an area of the screen containing approximately 400pixels. By matching the plotted points to the positions of the pixels, it is possible to avoid, or at least minimize, the distortion that can occur whenattempting to map from sample points to pixel locations when there is a mismatch between the two.

To see the result of such mapping problems, repeat the experiment shown in Figure 2 and use your mouse to stretch the Frame horizontally by a very small amount. Depending on how much you stretch the Frame, you should seevertical lines disappear, vertical lines that are too close together, or a combination of the two. This is another manifestation of the impact ofsampling that I don't have the time to get into at this point.)

The length of the pulse

As you can see in Figure 4 , the length of the pulse for this experiment was 11 samples, all but one of which had a value of zero.

(In this case, I could have made the pulse length 1 but for simplicity, I will keep it at 11 for several different experiments.)

Defining the origin of time

As you may have discovered by playing video games, we can do things with a computer that we can't do in the real world. For example, the Fourier transformprogram allows me to specify which sample I regard as representing zero time. Samples to the left of that sample represent negative time (history) and samples to the right of that one represent positive time (the future) .

In this case, I specified that the first sample (sample number 0) represents zero time. As you will see later, this has a significant impact on thedistribution of energy between the real and imaginary parts of the transform results, and as such, has a significant impact on the phase angle.

Computational frequency range

Because I am using a DFT algorithm (instead of an FFT algorithm) I can compute the Fourier transform across a range of frequencies of my choosing. Asshown in Figure 4 , I chose to compute the transform across the range of frequencies from zero to one-half the sampling frequency, known as the Nyquistfolding frequency. Thus, the spectral analysis was performed at 400 individual frequencies between these two limits.

The values that make up the pulse

The computational frequency range is followed in Figure 4 by the values of the samples that make up the pulse. Note that the first sample has a value of 180 while the other ten samplesall have a value of 0.

Results of spectral analysis on an impulse

I used the program named Graph03 to plot the output from this program, and the results are shown in Figure 5 .

(Note that rather than plotting each sample value as a vertical bar, Graph03 plots each sample as a dot and connects the dots with straight line segments.)

Figure 5. Spectral analysis of an impulse at zero time.
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Questions & Answers

what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
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
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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