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  1. n.karthick

    Field Oriented Control Clarification

    Hi, The controller is normally designed in such a way that it acts like a mirror image of the physical system it is going to control. In this case, the physical system i.e, the motor takes voltage as input and its response is measured as current. We know the mathematical model of the motor...
  2. n.karthick

    DC Drive rating to run DC Shunt Generator

    You may need to consider the losses in the motor (its efficiency) while calculating the required motor rating for your generator.
  3. n.karthick

    Simulink help for getting a frequency I can use as an input

    Hi, You can use PLL block in Simulink to find the frequency of the signal. Both single and three-phase PLLs are available in Simulink.
  4. n.karthick

    Three phase supply

    The phase means the angular difference between the sinusoidal voltage on one wire to another. For three phase, the angular difference would be 360/3 = 120 deg. Instead of having three independent single phase transmission system which require (phase + neutral wire for each phase) 2*3 = 6 wires...
  5. n.karthick

    Three phase circuits

    The arrow denotes the sign of voltage induced in the winding when current flows in that direction. For example if current flows from terminal n to R, the voltage across the winding denoted by VnR is positive.
  6. n.karthick

    How not to get stuck up with one approach?

    Hi, I am used to do things independently in my life and rarely takes the advice of others. The one important problem I often face is, whenever I try a method i always stick to it even if it doesn't work. I try to fight with the same approach to find solution to the problem in hand. Though I am...
  7. n.karthick

    Horoscope and its effects on marriage

    Hi I am from India, a Hindu by birth (Hinduism is a religion). Here horoscope match is considered essential for marriage. My horoscope was found to be bad since it contains" [Broken] (Mars danger) and naga dosha (snake danger). It is believed that if a...
  8. n.karthick

    Engineering How will having a master's degree in engineering change your career path ?

    I dont know about the status in your country. But I can say my experience in India. After completing my bachelor's degree in electrical engineering, I was able to get job as an electrical engineer. But the job profile was operation and maintenance of electrical machines in an aerospace...
  9. n.karthick

    Is it correct to give top priority for survival in academics?

    Yes, I discussed with my Prof. and requested him for making a simplified version of my big problem so that I can finish within in a month or so. But at this moment I don't have time to complete my original problem as such. But my inner consciousness always says that I am doing wrong. I am...
  10. n.karthick

    Is it correct to give top priority for survival in academics?

    Hi, I am a postgraduate student doing Master of Science(by research) in a reputed Institute in India. I registered for my course on January 2008 and I have not yet completed my course. The requirement for completion of this course is to get a research paper published in reputed journal...
  11. n.karthick

    Controllability Problem

    The variables A and B need not be symbolic variables. Just declare A and B as double floats and use ctrb function. It worked for me.
  12. n.karthick

    Drawing electric charge from the earth

    Why it will draw charge from earth? already the the capacitor and resistor are at zero potential. There is no closed path in the circuit and hence the capacitor cannot get charged. The law of conservation of energy has to be kept in mind. Work has to be done to charge a capacitor. Where does...
  13. n.karthick

    How to evaluate this indefinite integral?

    why cant u take x^3 inside square root. Then it will be simplified to sqrt(1-x^2)/x which is easier to integrate
  14. n.karthick

    Matlab: How to get the PSD of a signal?

    Which version of matlab you are using? i am using matlab 7.8 R2009a. In my version I have a function called 'dspdata.psd' in signal processing toolbox to find psd of input data.
  15. n.karthick

    Units of FFT in matlab

    The units of FFT will be in volts only as you mentioned but i dont know the procedure to get it in terms of other units.
  16. n.karthick

    MATLAB Hi everyone. im a beginner to matlab, i want to calculate the fourier

    you can use the fft function in matlab to find the frequency spectrum of the discrete signal. type 'help fft' in command prompt for more information
  17. n.karthick

    How to get amplitude and phase

    There are many methods available. Short time Fourier transform, Wavelet transform, least squares method, auto regressive methods etc.
  18. n.karthick

    What is the largest number less than 1?

    What about in the set of rational numbers Q which is countable
  19. n.karthick

    LaTeX Looking for TeX\LaTeX editor

    There are many LaTeX editors freely available. You can choose one based on the operating system you use and your personal favor. LyX is somewhat user friendly and good for beginners. TeXworks, TeXmaker are also good editors. I use TeXNiC center in Windows environment.
  20. n.karthick

    Matlab question; ezsurf

    Is 'e' in your equation is the exponential? if it is so then you have to use the Matlab function exp()
  21. n.karthick

    Is math physically real?

    In my view nature and math can be viewed as two intersecting circles A and B where A \cap B relates to the part of nature which has mathematical description as we know today. Still many things in nature remain to be mathematically described, which is A - B . Same way we have math for some...
  22. n.karthick

    Understanding concept of Zener Diodes for voltage

    The Vout will be negative (as Vin is negative and you are using non-inverting amplifier). This Vout is clipped by Z2 to -5.7 V
  23. n.karthick

    MATLAB Solve equtaion with sinh en coth in matlab

    Hi, declare Bi and t also as syms variables, it worked for me
  24. n.karthick

    Step up transformers - confusion

    It is not like that. Power loss in a cable is given by Ploss =I^2 R The voltage drop V in the cable depends on current I passing through the cable. This V is not the applied voltage Vs. Instead Vs= V+Vl where Vl is the load voltage (because resistance of cable is in series with load) So your...
  25. n.karthick

    Switching from parallel to series and keeping restistance the same.

    Oh I didn't notice that it is the current through X which is same, sorry. Equating voltage across X in both cases and solving that should give Y.
  26. n.karthick

    Switching from parallel to series and keeping restistance the same.

    I can give u a hint. Because the current is same (i) when Y is connected and (ii) Y disconnected and 50 ohm connected in circuit it means that total resistance in the circuit is same for both the cases. So you can equal the total resistance in 2 cases and solve for Y.
  27. n.karthick

    Newton's laws of motions

    I think both. How much A is pushed back and its acceleration after collision is given by II law, and III law says A is affected by its pushing against B.
  28. n.karthick

    The Energy Expended by a turning wheel

    I don't know math completely for finding energy to turn a wheel, but simply I can say that kinetic energy stored in a rotating wheel E=1/2*J*w^2 where, J is moment of inertia of wheel, w is the angular velocity. This is the energy,perhaps you have to impart to a standstill wheel to make it...
  29. n.karthick

    Passive Sign Convention

    The fact is current never enters the negative terminal of a resistor (in the sense you mentioned) and the power will never be negative.
  30. n.karthick

    Passive Sign Convention

    This is wrong example. A resistor can only dissipate power and it can't never supply power.