Fourier Sine Transform (FST)
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Introduction to Fourier Sine Transform
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Today, we are going to discuss the Fourier Sine Transform, commonly referred to as FST. Can anyone tell me what a transform is in mathematical terms?
Isn't it a method to change a function into a different domain, like frequency?
Exactly! Transforms allow us to move between function domains, helping us analyze and solve complex equations. The FST specifically uses sine functions. Can anyone recall the mathematical expression for the FST?
It’s the integral of f(x) times sine, right? From zero to infinity?
Correct! The FST is defined as F_S(ω) = ∫₀^∞ f(x) sin(ωx) dx. Great job! Let’s discuss why we might need this transform in engineering.
Applications of Fourier Sine Transform
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FST is used particularly for solving PDEs in semi-infinite domains. Does anyone know what type of problems these could be?
Maybe heat conduction problems or beam deflection?
Sine functions can represent odd functions, and they fit problems that start at zero, right?
Right again! The sine functions effectively represent starting conditions at zero. Keep remembering this relationship as we go further.
Inverse Fourier Sine Transform
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Now that we have the FST, let’s delve into how we can retrieve our original function. Does anyone know what the inverse of the Fourier Sine Transform is?
Isn't it something like f(x) = (2/π) times the integral of F_S(ω) sin(ωx) dω?
Spot on! The inverse transform allows us to get back to f(x) by integrating F_S(ω). Why do you think this step is essential in applications?
Because we need to get back our original function to analyze the physical problems accurately!
Exactly! The inverse transform is crucial for practical applications in engineering. Let’s summarize what we’ve learned.
Introduction & Overview
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Quick Overview
Standard
The Fourier Sine Transform (FST) facilitates the analysis of non-periodic functions, defined as integrals of the form involving sine functions. Its applications are particularly valuable in solving partial differential equations (PDEs) that arise in engineering contexts such as civil engineering.
Detailed
Fourier Sine Transform (FST)
The Fourier Sine Transform (FST) is defined mathematically as:
$$
F_S(ω) = \int_0^\infty f(x) \sin(ωx) dx
$$
where $f(x)$ is a piecewise continuous function on the interval from $0$ to $\infty$. The inverse transform is given by:
$$
f(x) = \frac{2}{\pi} \int_0^\infty F_S(ω) \sin(ωx) dω
$$
This transform is particularly useful in the analysis of partial differential equations (PDEs) with boundary conditions defined over a semi-infinite domain, commonly encountered in civil engineering applications such as beam dynamics and heat transfer. Understanding the FST allows for effective modeling and solving of various engineering problems through the manipulation of sine integrals.
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Definition of Fourier Sine Transform
Chapter 1 of 2
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Chapter Content
Z ∞
F (ω)= f(x)sin(ωx)dx
s
0
Inverse:
2 Z ∞
f(x)= F (ω)sin(ωx)dω
π s
0
Detailed Explanation
The Fourier Sine Transform (FST) is a mathematical operation that transforms a function f(x), which is defined over the interval from 0 to infinity, into a new function F(ω) in the frequency domain. The forward transform is represented as an integral of the function multiplied by the sine of ωx. In this formula, ω represents the frequency, and the integral ranges from 0 to infinity. The inverse transform allows us to recover the original function f(x) from the transformed function F(ω). It is also defined using an integral involving the sine function, which allows us to go back from frequency space to the time domain. This process of transforming and inverse-transforming functions is crucial in many applications, particularly in solving differential equations.
Examples & Analogies
Think of the Fourier Sine Transform like taking a photo of a sound wave. The original sound wave is like our function f(x), and the Fourier Sine Transform gives us a picture of how much of each frequency is present in that sound, represented as F(ω). If you want to recreate the original sound, you can use the inverse transform, much like using the photo to remaster or synthesize back the original sound.
Utility of Fourier Sine Transform
Chapter 2 of 2
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Chapter Content
These transforms are particularly useful for solving partial differential equations (PDEs) in semi-infinite domains.
Detailed Explanation
The Fourier Sine Transform is especially beneficial when dealing with partial differential equations (PDEs) that apply to semi-infinite domains. A semi-infinite domain refers to a physical system that extends infinitely in one direction but has a defined boundary in the other. For example, this could be a beam that is fixed at one end and free to oscillate at the other. By using the FST, engineers and mathematicians can simplify the complex equations that describe the behavior of such systems into forms that are more manageable to solve. This capability allows for analyzing the dynamic behavior of systems subjected to various loads or conditions over time.
Examples & Analogies
Imagine you are trying to predict how a long bridge will sway in the wind. The bridge’s behavior can be complicated and depends on various factors. By applying the Fourier Sine Transform, you can convert those complex behaviors into simpler mathematical forms, allowing you to calculate how much the bridge will move without needing to simulate every tiny detail. It's like turning a complex recipe into a simple list of ingredients that still produces the desired dish.
Key Concepts
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Definition of Fourier Sine Transform: A mathematical representation of a function using sine components.
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Significance in PDEs: The FST is crucial for solving partial differential equations in civil engineering applications.
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Inverse Transform: The means of retrieving the original function from its sine-transformed state.
Examples & Applications
An example of using the FST could be in modeling the vibrations of a simply supported beam, where you find the response due to a sine distribution of loads applied.
Heat conduction in a bar that starts at room temperature and then is subjected to a sudden change in temperature at one end can be analyzed using FST.
Memory Aids
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Rhymes
To find the wave, we take a dive; Sine rules apply, in math, we thrive!
Stories
Imagine a beam that bends in the breeze, we need the sine transform to calculate with ease!
Memory Tools
FST: Find Sine Transform; remember F, for Fourier, and S for Sine!
Acronyms
FST means Find Sine Transform to handle non-periodic signals in engineering solutions.
Flash Cards
Glossary
- Fourier Sine Transform (FST)
A mathematical transform that converts a function into sine wave components defined for non-negative values.
- Partial Differential Equations (PDEs)
Equations that involve multivariable functions and their partial derivatives, critical in engineering problem-solving.
- Inverse Transform
A procedure to recover the original function from its transformed form.
- SemiInfinite Domain
A domain that extends infinitely in one direction, often used in physics and engineering.
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