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# Missael Hernandez

##### Last seen: 1 month ago
14 total contributions since 2020

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Question

How to find the stiffness matrix in modal analysis.
How do I find the stiffness matrix when I know mass matrix, natural frequencies and mode shapes? I want to find a way by using M...

1 month ago | 0 answers | 0

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Question

How to plot phase portrait given a system of equations
Suppose I have the system represented as How would I plot the phase portriats for A=0.5,1, and 3? I know how to do it if I w...

4 months ago | 1 answer | 0

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Question

How to integrate a function over whose integrand upper limit is defined as an array?
Suppose I have this equation. I am trying to graph vs. for . I have a table of at given values such as I tried integr...

6 months ago | 2 answers | 0

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Question

How to superimpose certain indices of matrices.
In FEA, after we have the Global Stiffness Matrix of a Plane Frame Member, we construct and assemble the Plane Frame Structure S...

7 months ago | 1 answer | 0

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Question

How to superimpose certain indices of two matrices.
Suppose I have matrices K^1 and K^2. I would like to construct a globla stiffness matrix such that wwe add certain indices to co...

7 months ago | 1 answer | 0

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Question

Getting a "When simulating the response to a specific input signal, the input data U must be a matrix with as many rows as samples in the time vector T, and as many columns as input channels" error
I have a state space representation of a dynamical system. It 1 input and 3 outputs. I get the following error when I run my cod...

8 months ago | 1 answer | 0

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Question

How to solve s system of coupled nonlinear ODES already given the state vector
I have a nonlinear dynamical system. I have forund the eqautions of motion, which results in the following state vector: The...

8 months ago | 1 answer | 0

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Question

Getting error: Second argument must be a variable or a nonnegative integer specifying the number of differentiations.
I am trying to symbolically obtain the Euler-Lagrange equations, but I keep getting the "Second argument must be a variable or a...

8 months ago | 1 answer | 0

### 1

Question

Solve first order nonlinear ODE
Hello I am tryin to solve this nonlinear ODE with the IC This is my code tspan = [0 5]; x0 = 3; [t,x] = ode45(@(t,x) (...

9 months ago | 2 answers | 0

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Question

How to formulate the initial state vector for a BVP
If I have the following BVP, I am trying to solve, via shooting method. How would I formulate the state initial conditions given...

1 year ago | 0 answers | 0

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Question

Using ODE45 to solve a system of 2nd order ODEs equation
I am trying to solve This is what I have written as my finction script. everytime I try to solve it once I type the initial ...

1 year ago | 1 answer | 0

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Question

How to design an LQR for a response hold given state-space representation?
Hello I have a state-space model. My task is to design a controller that performs a response hold ('h' in my SS) at 50. It perfo...

1 year ago | 0 answers | 0

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Question

Hello I would like to add annotations to my bode plot exactly like Here is my code to the systems TF1=tf(1,[1 1]); TF2=tf...

1 year ago | 0 answers | 0