Recent content by mapi

Thanks. I am reading it.

Hi, How to plot gray color for a set of bars and white color for another set of bars? And also, how to put legend on? Thanks, mapi

I have group mean, 95% uncertainty (not std) and degrees of freedom (not integral) for each group. How do I compare the means? It seems that anova1 is not applicable. Thanks.

It is nonlinear, but we may approximate it with a linear curve, though not very good. Thanks.

Skogsgurra, Yes, the tube is soft, not infinitely stiff. So the tube will expand as pressure increases.

Thank you a lot. I(t)=dq/dt=d[C*V]/dt, I think we should put C(v(t)) into the derivative sign. For non-linear capacitance (not LTI system), I didn't know we can't transform it and get the impedance. My problem is this impedance, maybe it is not correct to obtain it just like LTI system: in...

Thanks for you questions. Yes, it is a mechanical system and I try to use circuit to simply the problem. So capacitance for example is C(V)=a*exp(-b*V)--a and b are constants. So C depends on the magnitude actually. voltage V(t) is not purely sinusoidal, but is periodic and has complex shape...

Thanks. we may say that the impedance I calculated in my last post is the impedance for that specific input, the pressure V(t).

Thank you all for your help. I think we may do it as: Given a voltage V(t), we can calculate the current through C(V).dV(t)/dt=I(t), then get the Fourier transform (FT) of V(t) and I(t), respectively. Now we calculate the impedance as: Z(w)=V(w)/I(W). Please correct me if there is any. Thanks.

BobM3, I asked some people in EE, they didn't say time-dependent impedance was wrong. For my problem, it is just a simplification of a tube with pressure inside, and so the compliance (capacitance) depends on pressure (voltage). Mapi

Bronzeado, Could you please give me the paper information if you know? Now I am concerned with the definition of impedance: voltage(t)/current(t) in time domain. If we want the impedance in the frequency domain, two methods: 1) FFT of voltage and current, then impedance is V(w)/I(w); 2)...

Unfortunately I do need this non-linear circuit, and try to see if such nonlinear circuit is better than linear circuit.

It is an analog: simply my current situation under study with a circuit. Then I need to calculate the impedance from circuit and fit it to the experimental data.

If just substitute equation of C into Z(w)=1/jWC, then Z(w) will be time-dependent, which seems not correct? In my case, capacitance is indeed dependent of voltage. When calculating impedance, do we do that in time domain or frequency domain? Complex V(t)/I(t) or V(w)/I(w)?

For a simple circuit with only one capacitor C, when C is constant, the impedance is Z(w)=1/jWC. But when C is dependent of the voltage, C(V), then what is the impedance? Thanks, Mapi