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# David Harra

Last seen: 13 days ago Active since 2021

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Question

How to tell if random points are in the same feature or not
I have a vornoi diagram populated with random points of 2 arrays. From each of the points I can calculate the distance between...

3 months ago | 1 answer | 1

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Question

Create line of pixels on an image
I am trying to achieve the Two Point Correlation function for a distribution of grain sizes. As a practice example, I have gen...

3 months ago | 1 answer | 0

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Can not envelope my data
I was looking to envelope my data so I can get the peaks and do some FFT on the data but when I go to envelope my signal I get a...

3 months ago | 1 answer | 0

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Question

Using Data to reconstruct an image
I have 2 images of grains, one that contains smaller and one that contains significanlty larger. Each material is achieved via a...

4 months ago | 1 answer | 0

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How to plot 3D plot from polar plot
I am looking at plotting the the slowness profiles of Titinium (Inverser of velocity) by solving the christoffell equation. I h...

4 months ago | 1 answer | 1

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How to get centre frequency of a pulse
I have an A-scan coollected from a simulation. I am trying to obtaon the the centre frequency from the initial pulse and I am un...

6 months ago | 1 answer | 1

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Question

Create Header with write matrix function
I have exported some data into a CSV file in from Matlab (144 x 4 matrix) At the top of each column I would like to add a titl...

6 months ago | 1 answer | 0

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Question

Grain Model how to remove smaller grains
I have a grain model which consists of lots of tiny grains and clusters of of larger grains. I am wondering how it is possible t...

6 months ago | 3 answers | 0

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Question

Fitting line to a curve
I have a plot of attenuation V frequency and I am wondering if there is a way I can fit a straight line the follows the upper tr...

8 months ago | 1 answer | 0

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Question

Attenuation as a Function of Frequency
I am wondering if anyone has any experience moddelling how attenuation of a material. I have made an attempt but my attenuation ...

8 months ago | 2 answers | 0

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Question

Pre Selecting Figures to plot
When I run my script I have 10+ figures plotting. Rather than commenting them out, I was wondering if there is a way to set up a...

8 months ago | 2 answers | 0

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Question

Zero Pad My FFT Signal and Window
Hi Everyone I want to know how I can zero pad my FFT signal to make it longer so that I can get better frequency resolution. In...

8 months ago | 2 answers | 1

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Question

Hanning window on Imported data
Hi everyone I am trying to add a hanning window to my time signal before I FFT it. I am not sure exactly what do. Looking at...

9 months ago | 1 answer | 0

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Question

FFT when rescaling data
Hi everyone I have been trying to use an FFT on my imported data. My Time step from my data wasn't equidistant so I tried to ...

9 months ago | 1 answer | 0

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Question

Frequency plot not working properly when using IFFT
I have impoted an ultrasound signal to matlab and I was to look at this signal in the frequency spectrum, but I am not sure if ...

9 months ago | 1 answer | 0

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Question

Normalising and rescaling my ultrasonic signal
I am exciting ultrasound in wateter which then gooes through the material. I want to notrmalise my signal in such a way that it ...

9 months ago | 1 answer | 0

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Question

Legend isn't including all entries
Hi everyone I am getting another error when creating my legend as one of my entries aren't showing figure(03) plot(Time...

9 months ago | 1 answer | 0

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Question

Error when creating legend
Hi everyone I am trying to print my legend on one of my figures as follows legend('Signal', sprintf('Amplitude = %0.04d', 9....

9 months ago | 3 answers | 0

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Question

changing values in an array
I have a 1000x1 array that ranges from 1 to 179. Any values above 90 in this array I need to do 180 minus any of those values ...

1 year ago | 1 answer | 0

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Question

Magnitude of a matrix
I have a 1000 x 3 matrix where each column is associated the the x,y and z-direction. For each row I want to find the magnitud...

1 year ago | 1 answer | 0

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Question

Error in Matlab code
I have attached a picture of my code with error message. It was working yesterday and now it is giving me an error and I don't ...

2 years ago | 1 answer | 0