calculating maximum acceleration that occured 3 time

Question

farid pr 2021-5-11

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/827630-calculating-maximum-acceleration-that-occured-3-time

评论： Walter Roberson 2021-5-16

采纳的回答： farid pr

Ax.txt

I need to find maximum acceleration that occured 3 times.I know that i need to use a loop for this problem like this :

false example code :

clc
clear all
A = [ 1 2 3 1 1 6 3 4 2 2 1 1 1 ];
N = 1
   while N <= 3
       N = numel(max(A)) + 1;
       find(hist(A,unique(A))= 3)
       r = A;
       disp(max(r));
       for N = 3
           disp(A)
       end
   end
cycle = A

this is my code :

clc
clear
close all
%Read acceleration txt file%
acc = textread('Ax.txt'); %g
size(acc);
PGA = max(abs(acc)) %g
T = (0:0.01:53.71);
size(T);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
acceleration = [acc]; %g
dt = 0.01;                       % change in time (seconds)
dtVel = acceleration * dt * 981; %(cm/s) = (acc * g * 100) * (s)
vel = cumtrapz([dtVel]);   %cm/s
PGV = max(abs(vel))      %cm/s
timev = dt * (0:length(acceleration)-1); 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
velocity = [vel]; %cm/s
dt = 0.01;                       % change in time (seconds)
dtDis = velocity * dt; 
dis = cumtrapz([dtDis]);   %cm
PGD = max(abs(dis))      %cm
timed = dt * (0:length(velocity)-1); 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%Plot%
x = T;
% 1st subplot
ax1 = subplot(3,1,1);
y1 = acc;
plot(ax1,x,y1)
grid on 
ylabel(ax1,'Acceleration(g)')
xlabel('time(s)')
% 2nd subplot
ax2 = subplot(3,1,2);
y2 = vel;
plot(ax2,x,y2)
grid on
ylabel(ax2,'Velocity(cm/s)')
xlabel('time(s)')
%3rd subplot%
ax3 = subplot(3,1,3);
y3 = dis;
plot(ax3,x,y3)
grid on
ylabel(ax3,'Displacement(cm)')
xlabel('time(s)')

7 个评论
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Adam Danz 2021-5-11

编辑：Adam Danz 2021-5-11

I'm confused by the disconnect between the image and what you're describing, "I need to find a max acceleration that occures 3 times(one acceleration at 3 points on time-line)." I think the word "max" is throwing me off. If the y-axis is acceleration, the red dots show the first n coordinates that intersect with a y-value. Those coordinates are not the max acceleration except for the one on the purple line.

If the y-axis in your image is "Max acceleration" where all points are a maximum acceleration of something, then the description matches the image a bit better, though still cryptic.

"If I had only one hour to save the world, I would spend fifty-five minutes defining the problem, and only five minutes finding the solution." -Albert Einstein

Adam Danz 2021-5-12

Moving my answer here because it no longer seems to apply to the evolving question.

Use findpeaks along with maxk to locate the 3 tallest peaks.

acc = readmatrix('https://www.mathworks.com/matlabcentral/answers/uploaded_files/614985/Ax.txt');

[yPeak, xPeak] = findpeaks(acc);

[maxPeaks, maxPkIdx] = maxk(yPeak, 3);

figure()

plot(acc)

hold on

plot(xPeak(maxPkIdx), maxPeaks, 'ro')

xlim([0 1500]) % zoom into relevant section

% Draw threshold line at the shortest of the 3 peaks.

shortestMax = min(maxPeaks);

yline(shortestMax, 'm-', sprintf('%.4f',shortestMax))

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Answer 1

farid pr 2021-5-16

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/827630-calculating-maximum-acceleration-that-occured-3-time#answer_701248

Hello again, Many thanks for your attention

I found a definition for my purpose(From Nuttli 1997) :

this parameter gives the sustained maximum acceleration/velocity during three cycles,and is defined as the third highest absolute value of acceleration/velocity in the time-history (note: in order for an absolute value to be considered as a "maximum",it must be larger than values 20 steps before and 20 steps after).