Need help with simulink

I am completely new to simulink and don't know where to start. I would like to create an object with certain intrinsic properties (proton density, T1 and T2 relaxation times, location within a magnetic field). This object would be susceptible to excitation with RF pulses that can resonate with the object's intrinsic frequencies. After excitation the object would release electromagnetic signals over time that are detected as voltages by a receiver/receivers.

Where do I start?

I can't figure this thing out for the life of me...

[Eric Diaz]

I'm not sure that this will ever get answered, but if someone with experience in simulink wants to help on a project, I can help direct what needs to get put into the simulation, as well as equations etc.

This is a personal project, not for any assignment, just fyi.

Once the project is finished, I foresee it being a contribution to the Matlab community and world.

Answer 1

[Azzi Abdelmalek]

What you need is to find the mathematical model representing your system. After you can simulate your model with Simulink

[Eric Diaz]

So, say for example, I have the model for the object and it is characterized by a first order differential equation, dependent on initial condition, intrinsic properties, time and location. How do I put that mathematical model into Simulink?

[Azzi Abdelmalek]

Give the mathematical model of such system

[Eric Diaz]

I'm sorry but I don't understand what you mean by that.

[Azzi Abdelmalek]

What do you want to simulate? your equations or transfer function, or maybe your state space representation

Look at this video

http://www.mathworks.com/videos/getting-started-with-simulink-69027.html

[Eric Diaz]

Basically wanted to create an MRI simulator with simulink. The models for describing the behaviors of protons are well described in the literature. The simulator would have a volume with various intrinsic properties. The volume would be excited with various RF pulse sequences. The volume would relax and behave according to models given by Bloch, McConnell and Torrey. This relaxation would give off signal detected by coils receivers. The signals could then be visualized and sampled, if desired, for further analysis. Simulink seems like a great environment for doing this sort of thing and I'm sort of surprised that no one has ever tried.

I watched several of the videos and fiddled around with various blocks and connections, but I can't figure it out. I had trouble just connecting a sinusoid block to the scope and visualizing it. I've forgotten most of my linear circuits and equivalent representations for differential equations. So, other than putting in an equation, I wouldn't know how to build the "model" using simulink blocks. Well, anyway, like I said, I would love to collaborate on the project with someone, if anyone is interested in making a contribution.

[Azzi Abdelmalek]

It's easy to use simulink, just provide your equations, I don't know what are your equations. To learn how to connect two block, just look at the video I showed you.

[Eric Diaz]

Haha...that's easy to say for someone who has been using it before. For someone who has never used it, it is very foreign. I'm sure that the learning curve is very steep, meaning easy to learn in a short time but difficult to get started. If I could have a basic setup for an object, located in 3D space, with ability to change intrinsic properties of that object. I would also need basic ability to excite and magnetize the object through main magnetic field and radiofrequency pulses. The behavior of the object would be governed by the Bloch-Torrey equations (https://en.wikipedia.org/wiki/Bloch_equations or https://en.wikipedia.org/wiki/Bloch%E2%80%93Torrey_equation#Bloch.E2.80.93Torrey_equation).

Ideally, at the end, the simulation setup would look similar to this setup ... https://www.youtube.com/watch?v=ThIqNvjPYd0

[Azzi Abdelmalek]

If you have never used Simulink before, then learn how to use it, begin with simple models. After you will have an idea how to use Simulink with your project. There are many getting started video in youtube. You can also read the Matlab documentation. Your question is not precise, then you can't get a precise answer. you didn't provide the mathematical model of your system, which has nothing to do with simulink. Once we have your mathematical model, we can speak about Simulink.

[Eric Diaz]

I'm not sure what you mean that I didn't provide the mathematical model of my system. As I mentioned before, the behavior is described by the Bloch equations. How is that not providing a mathematical model?

Answer 2

[Travis Adkins]

I need help with this problem for my matlab, i have no idea how to do it.