What is Transient: Definition and 200 Discussions

ECHELON, originally a secret government code name, is a surveillance program (signals intelligence/SIGINT collection and analysis network) operated by the United States with the aid of four other signatory states to the UKUSA Security Agreement: Australia, Canada, New Zealand, and the United Kingdom, also known as the Five Eyes.Created in the late 1960s to monitor the military and diplomatic communications of the Soviet Union and its Eastern Bloc allies during the Cold War, the ECHELON project became formally established in 1971.By the end of the 20th century, the system referred to as "ECHELON" had evolved beyond its military and diplomatic origins into "a global system for the interception of private and commercial communications" (mass surveillance and industrial espionage).

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  1. H

    What Causes the Transient Nature of Diodes in Semiconductor Junctions?

    A pn junction diode is driven by a voltage +E to -E volts preodically when voltage is +E its forward biases and vice versa. when in forward biased a current I flows through it, now if voltage is reversed to -E, current is still I (in reverse direction). This then stay constant for a time...
  2. M

    Derivation for Time to Max Radioactivity Transient Equilibrium

    Hi, I'm having a bit of difficulty deriving the time to max activity for the case of transient equilibrium for a parent-daughter. This is where I want to get to , tm = (1 / (λ1-λ2)) * 1n(λ1/λ2) I believe there is an alternative equation for tm as well expressed in terms of half-life...
  3. C

    Synchronous Generator transient response problem

    Hi , Hope someone could offer me a solution to this piece of code, the code below shows a period in time of a synchronous generator transient response, My scaling is the problem as I am not getting 50 Hz 230 volts, your help would be appreciated.. My efforts so far are % Transient...
  4. N

    Transient heat conduction in 1D solid

    1D solid, 0<x<L, with the following boundary conditions: The whole solid is at T = T1 at t=0. x = 0 is held constant at initial temperature T1 for all t. There is a constant flow of heat, dQ/dt out of the solid at x = L. T(0,t) = T1, T(L,0) = T1, How do we go about solving the heat equation...
  5. D

    Engineering Multisim Transient Analysis for LC parallell circuit

    Homework Statement The main problem is that I need help using Multisim for transient analysis of a simple LC parallell circuit. I am doing something wrong. C= 3*10^-5 F L= 3*10^-3 H The Capacitor is charged to 10V What happens to the energy of the capacitor when we connect it in...
  6. F

    R-L Transient Circuit: Find Time Constant & Energy Stored in Inductor

    Homework Statement A series R-L transient circuit is connected to a voltage source of E= 40V through a switch as shown. Suppose the switch is closed at time t=0μs and it was observed that the current iL flowing through the inductor rises to 4mA at time t=20μs and remains at 4mA after t=20μs.(i)...
  7. J

    How do you indicate transient terms when y just equals 1 ?

    how do you "indicate transient terms" when y just equals 1 ? t is the dependent variable in this problem and I'm told to "indicate transient terms". Well, t=1 so is this a trick question or did I do something wrong?
  8. Chronos

    Exploring Transient Radio Signals: Could They Be ET?

    This paper 'Provocative radio transients and base rate bias: a Bayesian argument for conservatism', http://arxiv.org/abs/1211.7338, discusses transient radio signals as possible signs of extraterrestrial intelligence. I knew of the 'WOW' signal, but, was unaware of other similar detection events.
  9. M

    Help calculating heat loss through transient conduction

    Homework Statement I have a stove, basically a metal drum which is the fuel chamber. Think of a hobo stove, just a metal drum with a fire in it. This stove creates convection heat via exhaust, and conductive heat to the metal drum itself which "slowly" releases the heat from there...now, I...
  10. L

    Heat transfer - Transient state involving a solid and a surface

    Homework Statement A thermometer for medical applications to determine the time required for the tip to reach a temperature of 37.95 C when in contact with the skin temperature of 38 C, starting from an initial value of 25 ° C. Admit that the tip of the thermometer is completely metallic...
  11. R

    Understanding Capacitor Transients: Solving for Initial Conditions

    Homework Statement Ok so I have attached the question I am working on. Basically when I have the circuit before or after switching in steady state I believe the current will equal zero. However if this is the case, how do I determine what happens immediately after switching? Homework...
  12. R

    Determining Steady State Current in an Inductor Transient

    1. The problem statement See attached question - So I have this inductor transient question and can't seem to get the right answer. Basically I don't know how to determine the current in steady state after switch operation.Homework Equations tau = L/C iL = a+be-t/tau V=IR The Attempt at a...
  13. S

    Engineering First-Order Circuit Transient Response Question that i with

    The switch in the diagram below has been open for a long time prior to t = 0; then it closes at t = 0 and opens again at t = 105 µs. Find: 1. Ix(75 µs), 2. Vx(75 µs), 3. Ix(190 µs), 4. Vx(190 µs). Attached is the diagram of the circuit and its answers. so i understand how to get...
  14. O

    Engineering Op-amp circuit peak current and swtiched circuit transient

    Homework Statement I have uploaded the questions in the attachment. I am having trouble with 2. e,f and 3.c untitled.png is the parts that I am having trouble with. untitled1.png and untitled2.png is the entire question. Homework Equations y(t)= steady state+transientThe Attempt at a Solution...
  15. P

    Engineering Capacitor transient charging equation of an RC series circuit

    Homework Statement I would like to derive the equation Vc=Vss+(Vi-Vss)*e^(-t/RC) Vss is the steady state voltage Vi is the initial capacitor voltage Vc is the capacitor voltage The Attempt at a Solution I tried to find solution using laplace transform. E=iR+1/c∫idt. Taking laplace...
  16. E

    Oscillations in transient response

    Why oscillations occur in transient response of a system ? Suppose transfer function of a system is 1/(s+1). Then its impulse response will be c(t)=e^{}-t . So why just we don't show only an exponential curve to graphically represent the impulse response, why we also show the oscillations ?
  17. I

    Engineering Determining current in a transient RC circuit

    Homework Statement For the below circuit, the switch was open for a long time. Find the current Ia(t) for t>0. All capacitors are initially uncharged.Homework Equations Complete response of a capacitor: v(t) = Voc + (v(0) - Voc)e^(-t/τ) Combining parallel capacitors: summation Current through a...
  18. M

    First-Order Nonlinear ODE from transient heat transfer

    A problem from a heat transfer book with conduction and radiation led me to a differential equation like this: T'(t) = a - b*T(t) - c*T(t)^4 Although my professor said that there wouldn't be an analytical solution for this one and to get the answer by an iterative method I got curious and...
  19. Z

    CR Transient Problem: Calculate VC at 3 Times

    Homework Statement The circuit shown in Figure 5 contains two emfs of opposite polarity E1 = 40 V, and E2 = -20 V. The circuit also contains a switch, resistors R1 and R2, and a capacitor C.The capacitor is initially discharged. The switch is connected to position ‘a’ for a period of 8...
  20. D

    Transient (unsteady) heat transfer over a sphere

    I AM DOING A PROBLEM ABOUT TRANSIENT HEAT TRANSFER AND IT SAYS: "A solid sphere of steel has 1 cm of diameter and a initial temperature of T0 =15 ºC. It is placed into a flow of Tinf = 60 ºC where the convection heat coefficient is h = 2000 W/(m^2K): (Density of steel rho = 7832 Kg/m^3 ...
  21. H

    Solving a 1D Transient Problem with Heat Equations and Lumped Capacitance

    Say you have a furnace wall at a temperature at 400 degrees C and you have oven gas at 200 degrees C and you place an copper rod into the furnace. The copper rod has an initial temperature of 25 degrees C and a length of 1 meter and a diameter of 2cm. You want to find what find the time it takes...
  22. M

    2D Transient Heat Transfer

    Im trying to write a MATLAB code for 2d transient heat transfer. The problem is a titanium block in the shape of a rectangle is staring at a specified temperature and is being exposed to a much hotter surrounding temperature. The dimensions, coefficients of heat transfer, and temperatures are...
  23. N

    More details on transient response

    Hi guys I just stepped into the electronic fields, I have some problems confusing me a lot I read my lecture notes but I was confused by a term transient response modes From my lecture notes, it describe this term in linear/first order and second order system But I'm still confused Like...
  24. I

    Transient heat conduction in a slab

    Homework Statement Consider unsteady state heat conduction through an infinitely wide slab of solid material of thickness 2L. There is no internal heat generation and the thermal properties of the material are independent of temperature and position. Starting from an energy balance, show...
  25. T

    Solving Transient Analysis RC: Find Capacitance for 200V, 20V, 2V

    1. The problem statement: What is the value of capacitance needed in Fig. 1 so that the voltage across the capacitor never exceeds (a) 200 V, (b) 20 V, and (c) 2 V ? This is the Circuit Homework Equations Vc(0-) = 0V Vc(0+) = 150V ic = c v' vc(t) = final + [initial -...
  26. S

    Engineering How Do I Start Designing a Transient Circuit with a 1 ms Time Constant?

    Hey, I know you have a rule requiring an attempt at the problem before posting here. The trouble is, I have a department required simulation project due this Wednesday and my professor is very behind in her lectures and has yet to even mention transient circuits. I don't expect this...
  27. B

    3 ways of transient processes, in LRC circuits

    Hello! For those that were with me at signals, I passed the exam, but barley. 10,5 points out 20. Going to cancel that exam and do it again when I have the chance. But anyway, back to the topic. I am trying to get the intuition for transient processes in RLC circuits. I was taught...
  28. B

    Software for transient states of circuits

    Hello, So is there any software, that generates the differential equation for the input circuit? I am trying to solve a problem and I want to check if my equation is right. Thanks.
  29. B

    How many boundary conditions should I have for a 2-D transient pde?

    Hello all: I'm a newbie, trying to write/use code for solving a 2D advection-diffusion problem. I'm not sure how many boundary conditions I should have for the property that is being transported. In my problem, I have diffusion switched off (advection only). The property being...
  30. D

    Engineering RC Circuit Transient Response Analysis

    Homework Statement In the circuit shown below the switch has been opened for a very long time and closes at t = 0. Calculate the output voltage VO at: 1: t = 0−; 2: t = 0+; 3: t = t1 = 24 µs; 4: t → ∞. In the circuit shown below the switch has been closed for a very long time and...
  31. G

    Time scale for the rapid transient

    Homework Statement Time scale for the rapid transient (overdamped bead on a rotating hoop). The governing equation m*r*φ'' = -b*φ' - m*g*sinφ + m*r*(ω^2)*sinφ*cosφ, can be reduced to ε(d^2φ/dτ^2) + dφ/dτ = f(φ). Using phase plane analysis it can be shown that the equation ε(d^2φ/dτ^2)...
  32. J

    Trying to decipher transient flow results

    Please Help! Trying to decipher transient flow results Hey guys, I'm currently studying a Bachelor of Aerospace Engineering and doing my honours level research project in a field called Active Flow Control. A brief intro to what the project involves: The motivation of the project is to...
  33. R

    Transient Heat Transfer in Radial Direction

    My geometry is bit complex. I want to make a heat transfer model based on FDM in the radial direction. But it has become very difficult to discretize the domain because of multiple materials. As the segments are symmetric, I want to model the heat transfer in one segment. My schematic is given...
  34. X

    Show all other states are transient in Markov chain

    Let X be a Markov chain with a state s that is absorbing, i.e. pss(1) = 1. All other states communicate with s i.e. i → s for all states i ∈ S. Show that all states in S except s are transient. I understand this intuitively, but I'm not really sure how to start the proof.
  35. G

    Transient Thermal Analysis in Ansys (APDL)

    Hi, I have to model a transient thermal problem in Ansys. I just need an outline of how I should proceed. The Problem: I am trying to model the cooling of a solar collector reciever tube from 150 degree celsius to ambient. My attempts have involved the following: 1. Initial condition...
  36. S

    Transient analysis in heat transfer

    Hi All, I'd be grateful if helped in this understanding; I'm following the attached pages to solve a numerical problem by Forward difference, backward difference and central difference- in fact to be precise, deriving the transient solution approach to a heat transfer problem--- In the...
  37. R

    Heat transfer electrical annalogy (transient)

    Hallo, I have been trying to find some bibliography about this issue, but all what I found it is very simple and always discarding the effect of the Thermic Capacity of the elements. I have to work with matherials which operate in transient conditions and which have parts which accumulate...
  38. K

    Transient heat transfer 2-D cylindrical

    Hi All I'm embarking on a model of a large physical system. I have a reasonable concept of the model but need advice on which simulators or programming languages to use. I've developed a (simple) explicit finite difference algorithm in excel for 'a few metres' and 'a few timesteps'. I have...
  39. A

    Analytical Solutions for 1D Transient Heat Conduction in Cylindrical Coordinates

    Hi, I have written a numerical code to solve the 1D heat equation in cyclindrical coordinates: \frac{\partial T}{\partial t}=\kappa\left(\frac{\partial^{2}T}{\partial r^{2}}+\frac{1}{r}\frac{\partial T}{\partial r}\right) The problem I'm considering is a hollow cylinder in an infinite...
  40. L

    Capacitor transient response, what happens in the dielectric?

    I'm trying to marry the concepts from my EM course with what I've been doing in my lab course. Correct me if I'm wrong, in a plain RC circuit, when closed with a DC source, the capacitor initially acts as a short (voltage is zero across the terminals, while I is max), until after a few...
  41. Pythagorean

    Transient electric nanotubes connect non-neuronal cells

    :bugeye: http://www.pnas.org/content/107/40/17194
  42. T

    Transient Stability Analysis for Solar-Integrated Electrical Grid

    Hello Guys, I am planning to design electrical grid connected with solar distribution generation system using ETAP. I tried to run trasinet stability analysis of this system with fault at each and every line/branch of the system, to get corresponding critical clearing times. I realized that...
  43. S

    Switching losses ESR and transient response

    I need someone to tell me if what I am saying is true or BS? Switching Frequency: Is simply defined as the frequency (amount of times) the same operation occurs, in our case the amount of times per second each phase is switched on. Duty Cycle: is thought of as the time the object is on...
  44. D

    Transient Thermal Analysis- Ansys APDL Help

    Hello All, I have to do a transient analysis of thin composite film. Following are the requirements: 1. Time t=0 to t=0.01, Initial condition of Temperature=300 K. 2. Time t=0.01 to t=0.05, Temperature=505 K. 3. Run the analysis from t=0.05 until a stable solution is obtained. I tried...
  45. P

    Transient conduction problem

    1. A large block of steel [k=45 W/m°C, alpha=1.4x10^-5 m2/s] is initially at a uniform temperature of 35 C. The surface is suddenly exposed to a constant heat flux of 3.2x10^5 W/m2 Find the temperature at a depth of 2.5 cm after 30 seconds has elapsed.
  46. Isaacsname

    Unexplained transient weight gains after death

    Ok, my apologies if this has been dissected on PF before, I did do a few searches and didn't stumble into anything, there doesn't seem to be much info online. Is it woo-woo or legitimate ? ----- Unexplained Weight Gain Transients at the Moment of Death Journal of Scientific Exploration...
  47. J

    RLC DC Transient over-damped response

    Hello All, I have a bit of a problem with a series RLC circuit with no supply voltage. In the process of actually solving the second order differential equation for the voltage across the capacitor I have lost a handle on what it actually represents in terms of the circuit. I have attached...
  48. G

    General Solution and Transient Terms

    Homework Statement Find the general solution of the given differential equation. Give the largest interval over which the general solution is defined. Determine whether there are any transient terms in the general solution. Homework Equations x(dy/dx) + 2y = 3 The Attempt at a...
  49. S

    Transient response of a system (control)

    Homework Statement Find T,K value such that the system's percent overshoot is .254 and peak time is 3 http://img560.imageshack.us/img560/6139/problemz.png Homework Equations [PLAIN]http://img46.imageshack.us/img46/51/releq.png The Attempt at a Solution...
  50. A

    Transient and subtransient reactance of alternators

    please explain the transient and subtransient reactance of synchronous machines
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