# Java1478-fun with java, how and why spectral analysis works  (Page 4/9)

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(The curve in Figure 4 can also be considered to consist of the sum of two parts. However, in Figure 4 , the bias value is zero.)

## The net area

The net area contributed by the periodic part of the curve in Figure 5 continues to be zero. In effect, the non-zero net area under the curve in Figure 5 is the amount of the positive bias multiplied by the number of points. In other words, because I captured an even number of cycles of the periodic portionof the curve in my calculation of net area, only the bias contributes a non-zero value to the net area under the total curve.

## Part of a cycle

Had I failed to capture an even number of cycles of the periodic portion of the curve, then the positive lobes might not completely cancel the negativelobes, and the net area under the curve would be influenced by the periodic portion of the curve in addition to the bias.

## Why is this important?

These concepts are extremely important in this module as we learn how to do frequency spectral analysis.

As you will see in this module, in doing frequency spectral analysis, we will form a product between a target time series and a sinusoid. The purpose is tomeasure the power contained in the time series at the frequency of the sinusoid.

The product of the target time series and the sinusoid will produce the sum of a potentially infinite number of periodic functions, some of which may beriding on a positive or negative bias. We will measure the amount of bias by computing the average value of the product time series. The amount of bias willbe our estimate of the power contained in the target time series at the frequency of the sinusoid.

## The Fourier transform

There is a mathematical process, known as the Fourier transform, which can be used to linearly transform information back and forth between two differentdomains. The information can be represented by sets of complex numbers in either or both domains.

The domains can represent a variety of different things. In DSP, the domains are often referred to as the time domain and the frequency domain , but that is not a requirement. For example, one of the domains could representthe samples that make up the pixels in a photograph and the other domain could represent something having to do with the manipulation of photographs.

Usually when dealing with the time domain and the frequency domain, the values that make up the samples in the time domain are purely real while thevalues that make up the samples in the frequency domain are complex containing both real and imaginary parts.

## Time domain and frequency domain

For some purposes, it is preferable to have your information in the time domain. For other purposes, it is preferable to have your information in thefrequency domain. The Fourier transform allows you to transform your information back and forth between these two domains at will.

For example, it is possible to transform information from the time domain into the frequency domain, modify that information in the frequency domain, andthen transform the modified information back into the time domain. This is one way to accomplish frequency filtering.

what is variations in raman spectra for nanomaterials
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
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
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
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
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 did you get the value of 2000N.What calculations are needed to arrive at it
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