# Search results

1. ### Control Systems Engineering - Block Reduction Help

Homework Statement Hello, I'm trying to reduce the following block diagram Homework Equations The Attempt at a Solution I appear to be having some issues in doing this. The first thing that I did to reduce this block diagram was to take the forward path that has 2/(s+4) with negative...
2. ### Autocorrelation Function of a Signal

I actually didn't know this E[F(f(t))F(g(t))] = E[F(t)F(g(t) -f(t))] = R_{FF}(g(t) - f(t))? If I were to try and find the power spectral density of X(t) I would make use of S_{XX}(f) = F[R_{XX}(\tau)]. Were F[] is the Fourier Transform. S_{XX}(f) = F[2*delta(\tau) - delta(\tau - 1) -...
3. ### Autocorrelation Function of a Signal

Hey MathematicalPhysicist, Thanks for the reply. I didn't realize this was so simple. My new attempt at a solution I know that . But I don't understand how this equation is true . It reminds of the simple fact that if LHS = RHS LHS + 1 = RHS +1 But that doesn't seem to be the case here...
4. ### Digital Communication Systems - Autocorrelation

sorry I didn't mean to post
5. ### Autocorrelation Function of a Signal

Homework Statement I'm posting this question here at this point. I am having difficulty understanding autocorrelation in terms of solving the problem below. I don't seem to understand the math behind this. A white noise process W(t) with unity (N_0/2 = 1) power spectral density is input to a...
6. ### Engineering Simple Circuit Problem (Clarification of doubts)

The value for I_x doesn't seem to be correct. I'm not exactly sure how you got the value that you did. The node to the left of the 5 ohm resistor there's only three paths for current to flow through. It looks like your summing the currents at node A when you solve for Ix? If this is the case...
7. ### Engineering Simple Circuit Problem (Clarification of doubts)

Oh ok let me look through this again.
8. ### Engineering Simple Circuit (RL circuit)

What about the voltage across the inductor?
9. ### Engineering Simple Circuit Problem (Clarification of doubts)

When you did your conversion, point B shouldn't be connected to ground, it wasn't in the original problem before the conversion.
10. ### Engineering Simple Circuit (RL circuit)

I would recommend not memorizing such equations. It really makes things complicated when presented with problems that don't fit them. There are several ways you could solve the problem. Do you know the equation for KVL for after the switch is opened?
11. ### Digital Communication Systems - Autocorrelation

Homework Statement A white noise process W(t) with unity (N_0/2 = 1) power spectral density is input to a linear system. The output of the linear system is X(t), where X(t) = W(t) - W(t - 1) Determine the autocorrelation of X(t) and sketch it. Homework Equations Let τ denote a time...
12. ### Article that Explains IGBT well

Hi, I'm an undergraduate EE major and am having trouble understanding IGBT. I understand the basic principle, a PNP transistor in ? (forgot the name) configuration with a MOSFET with a parasitic NPN transistor. I understand that it's a 4 layered device. I however think I would struggle trying...
13. ### Electrical Engineering - Control Systems - Design Via Frequency Respon

My text says that we can find the frequency, ω_{max} at which the maximum phase angle, Θ_{max}, occurs ω_{max} = \frac{1}{T\sqrt{β}} But this doesn't really seem to help since I don't know the frequency ω_{max}, unless it's the bandwidth frequency ω_{BW}, which I don't think it is. My text...
14. ### Electrical Engineering - Control Systems - Design Via Frequency Respon

For a lead network G_{c}(s) = \frac{1}{β}\frac{s + \frac{1}{T}}{s + \frac{1}{βT}} I'm still unsure where \frac{1}{\sqrt{2}} came from though. There's a standard representation for the compensator C(s)? Edit 1: From the characteristic equation 1 + kG(s)C(s) = 0 kG(s)C(s) = -1 kG(s) = -...
15. ### Electrical Engineering - Control Systems - Design Via Frequency Respon

done editing Homework Statement I'm given the following transfer function that represents a physical apparatus G(s) = \frac{X(s)}{F(s)} = \frac{3.333*10^{4}}{s^{2}} I'm asked to design a lead compensator to achieve closed-loop stability. The requirements are that it must have a transient...
16. ### Combined Translational & Rotational System Transfer Function

Thanks for your response. Should this go in the advanced physics forum? This question is actually from a control systems class, but I posted it in the physics forums because I'm having a hard time understanding the physics behind this problem, especially the free body diagram. I was able to...
17. ### Combined Translational & Rotational System Transfer Function

Homework Statement I'm given the following diagram And asked to find the transfer function G(s) = \frac{X(s)}{T(s)} and seem to be having some difficulty doing so. Homework Equations The Attempt at a Solution Apparently this is free body diagram I seem to be having difficulty...
18. ### Electrical Engineering - Control Systems - 2cnd Order System

Homework Statement Given a electrical circuit as one below One can find the transfer function For second order systems this can be written as I know that the damping coefficient can be found using the following formula In the over damped case ζ>1 can easily occur depending on the...
19. ### Control Systems Engineering - Signal Flow Graphs

Hi, I seem to be having some issues going from state space representation of a system to signal flow graph representation. My troubles seem to be, if I have something like this \frac{d}{dt}x_{1}(t) = v_{1}(t) In state space representation I list functions to which the derivatives are as...
20. ### Digital Logic - Tri State Buffers

Homework Statement I'm trying to implement the function F = A'BC+ABD+AB'D' using 3 tri-state buffers. Apparently I'm supposed to connect the buffers together and use C, D, and D' as inputs to buffers. I'm supposed to pass A and B through logic to get the input signals. I'm supposed to...
21. ### Buck dc-dc Converter w/Control System Analysis

Well you've stumped me to stay the least, and I'm a bit concerned by suggesting that the problem can't be solved I did not realize that I could think of the transistor and the diode as a switch. This may lead me in the right direction. I'm not exactly sure why it could be considered a switch...
22. ### Buck dc-dc Converter w/Control System Analysis

Homework Statement I'm given the following circuit http://imageshack.com/a/img850/8576/b3ny.png [Broken] and given L, V_{in}, D, P_{o}, f_{s} and q(t). How do I go about finding T_{s}, V_{a}, i_{L}, i_{L} ripple, and I_{o}. Homework Equations The Attempt at a Solution I'm honestly not...
23. ### Control Systems Engineering - Masons Rule Help

So if I wanted positive Vload/Idist it would just be the opposite magnitude, -1/(CFS)?
24. ### Simulink Help Drawing ODE

Homework Statement Hi, I was wondering if someone could help me create a basic differential equation in Simulink. I'm trying to create the following equations http://imageshack.com/a/img197/1379/cic.PNG [Broken] I tried using this as an example...
25. ### Inverse Laplace Transform Help

So if you have no idea what one of the functions in the frequency domain is and you get something like inverse Laplace transform( F(s)G(s) ) and you know what G(s) of is but F(s) is not given then you have no way to evaluate the expression?
26. ### Transfer Function to State Space Calculator Program

Hi, Does anyone know a program that I can put on my TI-84 calculator that will allow me to input any transfer function and get the state space representation of the system or the other way around. For example G(s) = \frac{\sum(K_{i}s^{i})}{\sum(P_{i}s^{i})} The calculator prompts you...
27. ### Control Systems Engineering - Masons Rule Help

Is it really just -\frac{C_{f}s}{1 - C_{f}s}?
28. ### Control Systems Engineering - Masons Rule Help

Homework Statement I'm trying to find \frac{V_{Load}(s)}{I_{Dist}(s)} using Mason's rule. I was able to solve for \frac{V_{Load}}{I_{Cf}(S)} using Mason's rule but am not sure how to solve for \frac{V_{Load}(s)}{I_{Dist}(s)}. http://imageshack.com/a/img31/4299/zr5.PNG [Broken] Homework...
29. ### Inverse Laplace Transform Help

Homework Statement Is there a way to evaluate L^{-1}(\frac{F(s)}{s + a})? I'm sure if it can be evaluate. Homework Equations The Attempt at a Solution
30. ### Engineering Transfer Function and State Space Analysis of Op-Amp circuit

Homework Statement http://imagizer.imageshack.us/v2/800x600q90/690/0tab.png [Broken] [Broken] I'm asked to find the transfer function and then find the state space representation and seem to be stuck. Homework Equations The Attempt at a Solution My textbook states that for a...
31. ### Electrical Engineering - State Space - Matlab

Homework Statement \dot{} I'm given the following circuit http://imagizer.imageshack.us/v2/800x600q90/43/bwka.png [Broken] Homework Equations The Attempt at a Solution I come up with the transfer function to be G(s) = \frac{s}{2+\frac{1}{s}}. The question asks me to...
32. ### Differential Equation, Solve for function

How would you recommend solving this problem then, if there's a much easier way to solve this than I would like to know how that can be done. Resolving that into partial fractions is very difficult to do.
33. ### Laplace Transform Within a Domain

Thanks, I was able to figure it out
34. ### Laplace Transform Within a Domain

So this problem becomes L(t*u(t) - t*u(t-T)) = \frac{1}{s^{2}} - L(t*u(t-T)) = \frac{1}{s^{2}} - \int^{∞}_{0^{-1}}e^{-st}t*u(t-T)dt = \frac{1}{s^{2}} - \int^{∞}_{0^{-}}e^{-st}tdt Now I do u substitution to evaluate the integral. u(t) =t, \frac{du}{dt} = 1. \int dv = \int e^{-st}dt =...
35. ### Differential Equation, Solve for function

Homework Statement Given \frac{dx}{dt} + ax = Asin(ωt), x(0) = b Solve for x(t) Homework Equations The Attempt at a Solution I take the Laplace transform of both sides and get sX(s) - x(0) + aX(s) = \frac{Aω}{s^{2} + ω^{2}} X(s) = \frac{b}{s + a} + \frac{Aω}{(s^{2} + ω^{2})(s+1)} The...
36. ### Laplace Transform Within a Domain

Homework Statement Find the Laplace transform of f(t) = t \forall 0≤t≤T, 0 otherwise Homework Equations The Attempt at a Solution I write the function as tu(t)-t*u(t-T) That is turn on the function t at t=0 and turn the function t off at t=T. It seems to be right to me...
37. ### Engineering Control Systems Engineering - Circuits

Homework Statement Find the transfer function, G(s) = \frac{V_{0}(s)}{V_{i}(s)} for each network shown in figure P2.3. [Section 2.4] http://imagizer.imageshack.us/v2/800x600q90/20/1ocq.png [Broken] Homework Equations The Attempt at a Solution When I try and solve this problem...
38. ### Interference of Light - Thin Film

Thanks for all of the help guys. It make since to me now. I clicked on all of the links, but was shocked by the link in #6 that went to a AP Physics B class website. I took that class four years ago and learned this material then, apparently I have forgotten all about it in such a small amount...
39. ### Interference of Light - Thin Film

This is interesting no one has ever explained this to me. How do I know when they invert and how do I know when they don't? Δ = Δ_{p} + Δ_{r} The inverted wave travels 2t as far since it travels through the thickness twice, so then why do we use 2nt as apposed to just 2t for thin film...
40. ### Interference of Light - Thin Film

My book doesn't mention this until Michelson interferometer. It doesn't explain why your supposed to use lambda/2. It appeared in my lecture in thin film interference. I can't seem to find though any explanation as to where it comes from. I also have searched the internet for some sort of...
41. ### Interference of Light - Thin Film

Homework Statement Plan plates of glass are in contact along one side and held apart by a wire 0.05 mm in diameter, parallel to the edge in contact and 20 cm distant. Using filtered green mercury light (λ = 546 nm), directed normally on the air film between plates, interference fringes are...
42. ### Doppler Effect of a laser

Wait hold on. What allows us to simply replace the wavelengths with the frequencies and just interchange them? I thought that the equation applied to wavelengths. Oh ok I know why lol.
43. ### Doppler Effect of a laser

Ya. I just read underneath that part and it says that when v << c Eq. (4-44) (the equation I posted in the first post for the Doppler Effect) is approximated by \frac{λ^{'}}{λ} = 1 - \frac{v}{c} Which I didn't realize. I remember reading it earlier but it left my mind because I would...
44. ### Doppler Effect of a laser

Homework Statement A laser emits a monchromic beam of wavelength λ, which is reflected normally from a plane mirror, receding at a speed v. What is the beat frequency between the incident and reflected light? Homework Equations The Attempt at a Solution The solutions starts off...
45. ### Laser Operation - Gain Media

I have just read the caption of the figure and now realize that v_{p}≈\frac{E_{3} - E_{0}}{h}. The only problem now is that I don't know E_{3} or E_{0}. Looks like I might be able to solve this. I was able to solve the problem. My only concern is that I didn't use the given wavelengths in the...
46. ### Laser Operation - Gain Media

I'm not sure if this question should be posted in the introductory physics section or the advanced physics section. Consider an amplifying medium, composed of homogeneous broadening four-level atoms as show in figure 26.5, page 557 of textbook. http://img689.imageshack.us/img689/6108/lt2f.png...
47. ### Superposition of Waves - Standing Waves

Oh wow. I can't believe I didn't see that thanks.
48. ### Superposition of Waves - Standing Waves

Homework Statement Consider a situation in which a wave is traveling in the negative x-direction encounters a barrier and is reflected. Assume an ideal situation in which none of the energy is lost on reflection nor absorbed by the transmitting medium. This permits us to write both waves with...

never mind
50. ### Dispersive power of glass

Homework Statement The dispersive power of glass is defined as the ratio \frac{n_{F} - n_{C}}{n_{D} - 1}, where C, D, and F refer to the Fraunhofer wavelengths, λ_{C} = 6563 \stackrel{o}{A}, λ_{D} = 5890 \stackrel{o}{A}, and λ_{F} = 4861 \stackrel{o}{A}. Find the approximate group velocity...