Parameters Definition and 534 Threads

A parameter (from the Ancient Greek παρά, para: "beside", "subsidiary"; and μέτρον, metron: "measure"), generally, is any characteristic that can help in defining or classifying a particular system (meaning an event, project, object, situation, etc.). That is, a parameter is an element of a system that is useful, or critical, when identifying the system, or when evaluating its performance, status, condition, etc.
Parameter has more specific meanings within various disciplines, including mathematics, computer programming, engineering, statistics, logic, linguistics, electronic musical composition.
In addition to its technical uses, there are also extended uses, especially in non-scientific contexts, where it is used to mean defining characteristics or boundaries, as in the phrases 'test parameters' or 'game play parameters'.

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  1. V

    How Do You Solve the Homogeneous Equation for ty''-(t+1)y'+y=0?

    ty''-(t+1)y'+y=t^2 I know I have to use variation of parameters to solve this. But I am stuck and cannot figure out how to get the homologous equation! y''-(1+\frac{1}{t})y'+\frac{1}{t}*y=t I don't know how to solve this homologous equation in this format. Is it R^2+(1+1/t)R+1/t = 0 ? How...
  2. A

    Mathematica FindRoot with 2 variables plus parameters (Mathematica)

    Hi all, I have a hard time finding roots to the following system of equations in 2 unknowns (p,q): eq1 = Pu == f(q, alfa, beta) eq2 = Ql == g(p, alfa, beta) If the 2 parameters (alfa, beta) are given numerical values beforehand, no issue. But I would like to retain the parameters in...
  3. C

    Question on variation of parameters - ODE

    I am working on a problem requiring variation of parameters. When I calculated the wronskian, I got an answer, which differed from the book only by a "-" (mine was -, the book's was +). So I switched my functions for y1 and y2 and got the answer the book had. Is there a standard for which...
  4. R

    Variation of parameters and the constraint

    I have already read one thread on Lagrange's method of variation of parameters and it was very useful, but I am still confused about the use of the constraint. If the solution to the homogeneous second order equation contains two functions, with arbitrary constants: y= Ay1 + By2...
  5. R

    How Can I Use Variation of Parameters to Solve Differential Equations?

    I am trying to solve a problem along the lines of y'' + 2y' + y = e^(-x) (2 + 1/x^2).. The actual one I am trying to solve differs slightly. I was trying to solve it using the method of variation of parameters.. However it is new to me and was too confusing. So first I get: y comlpiment...
  6. P

    Variation of Parameters problem

    Homework Statement Find a particular solution by method of variation of parameters: t2y'' - 2y = 3t2 - 1 given: y1 = t2 y2 = t-1 Homework Equations The Attempt at a Solution I get Y(t) = t^2ln(t) - \frac{1}{3}t^2 + \frac{1}{2} The book gives Y(t) = t^2ln(t) +...
  7. N

    Engineering Thevenin equivalent circuit parameters

    Homework Statement https://www.physicsforums.com/attachment.php?attachmentid=32837&stc=1&d=1299373667 Determine the Thevenin equivalent circuit parameters, VTh and RTh, referred to terminals A and B of the circuit shown below? Homework Equations The Attempt at a Solution My...
  8. R

    Flight Mach number in terms of fuel flow rate and other parameters

    I've posted on here in relation to an aerospace analysis project I'm doing. I'm stuck on one part of the project where I need to develop the performance envelope of the turbojet engine. 3 of the 9 plots that are required are Thrust vs. Mach number. On each of those plots I'll about 7 different...
  9. X

    Solution to a DE using variation of parameters

    I was looking through my DE book and a problem intrigued me. I eventually figured it out but I do not understand the logic. I was wondering if anyone here could help me out. The question says: Use the method of variation of parameters to show that...
  10. R

    Understanding SMPS Parameters: Burst Duty, Frequency & More

    Hi, I am doing an application regarding SMPS. In the project i encounter the terms "Burst duty, burst frequency, Timing/phase shift and timing/ dead time". Can anyone explaine me about those parameters and how they are important in SMPS working.
  11. Z

    IR divergences by analytic continuation of parameters

    i had a discussion with a physicist i proposed that in order to avoid the IR divergence \int_{0}^{\infty}dx(x-a)^{-3}x^{2} we could propose as regularized value the value of F(-a) , where F is the integral \int_{0}^{\infty}dx(x+b)^{-3}x^{2} so if we could regularize this simply...
  12. R

    Scaling parameters in central difference solution

    Hi, I developed Matlab code to solve the diffusion equation using the central difference equation, with an added term at the end. The equation is the following: dS/dt=Ds*d^2S/dx^2-(Vmax*S/Km+S) In my code, the length of the space domain is very small, 1E-6. I would like to scale...
  13. R

    Density Parameters using Mathematica

    Homework Statement hello, I have to solve a couple of equations on Mathematica for a project, and since they are not really working out, I wondered if you could help me out a bit. I need to solve equation (1) (you can find the equations in the .doc attached) and plot the solution for a...
  14. brainpushups

    Uncertainty in the parameters A and B for a linear regression

    I'm working through John Taylor's An Introduction to Error Analysis and so far this is the only problem I haven't been able to solve. I was hoping someone could lend me some insight. The problem asks you to use error propagation to verify that the uncertainties in A and B for a line of the...
  15. U

    Equation for Ellipse from a chord - no other parameters

    Equation for Ellipse from a chord -- no other parameters! Homework Statement Known conditions are: End points of the chord intersect the major and minor axis. Proximity to nearest parallel tangent. Known (hypothetical) values are: The length of the chord is 10. The chord is 1.25 from...
  16. H

    Relationship of diffrent parameters of Gas turbine

    Hi friends; I have Saturn 1100 and centaur 4500 two shaft gas turbines from solar INc. I want to know that what relationship of following parameters 1. Compressor discharge pressure and fuel flow 2. How i calculate the SFC? 3. What effect of LHV on SFC? 4. How i calculate the Heat rate? If...
  17. B

    Use of FFT to recover parameters of waves

    Hi, everyone: As I am sure will be clear from my post, I am not--nor have I ever been-- an EE :). (For the sake of giving some context to help taylor the answer, I am a mathematician-in-training. I only know the most basic ideas of signal-processing but I do know...
  18. G

    Find an example for 2 planes with parameters

    I have to find two planes z=f_1(x,y)=a1*x+b1*y+c1 z=f_2(x,y)=a2*x+b2*y+c2 That satisfy: 1. both planes go through (-5,9,8) 2. the intersection line between the planes is located outside of the Cylinder x^2+y^2=4 3. the surface area of x^2+y^2=4 that is bounded between f1 and f2 is...
  19. A

    Finding STO3G Parameters for H,He,C,N,O

    Dear all, I need the parameters for the STO3G basis set H,He,C,N,O. Where can I get them? Thanks, Eric.
  20. O

    Suitable op-amps/ parameters for subtractor circuits

    Hi all, I would like to know which op-amps are more suitable for an analog voltage subtractor circuit? Are there any parameters of the op-amp that I should take special note of, which has a more crucial effect on the subtractor circuit? Thanks for your help in advance!
  21. M

    Calculating Flow Rate of a Fan Using Parameters

    I wonder if there is a mathematical formula to calculate the flow rate of a fan if following parameter are known Fan effective diameters Blade Angle ( Pitch ) Number of Blades Speed ( RPM ) Power Consumption Pressure at inlet of the fan Regards
  22. B

    Variation of Parameters Nonhomogeneous Differential Equation

    Homework Statement 4y'' + y = cosx Solve using variation of parameters Homework Equations The Attempt at a Solution from a) -> yc(x) = c1cos(x/2) + c2sin(x/2) let y1 = cos(x/2) , y2 = sin(x/2) y1y2' - y2y1' = 1/2cosx/2 + 1/2sinx/2 = 1/2 u1' = ? How do I find this?
  23. M

    Improper integrals with parameters

    Homework Statement Let f be continuous on the interval [0,inf] with abs(f(x)) < M, set F(u) = \int \frac{u*f(x)}{u^2 + x^2} integral from 0 to inf (bad with latex) prove that lim F(u) as u --> 0 = f(0)Homework Equations noneThe Attempt at a Solution I split the integral into the intervals...
  24. K

    Calculating Work to Fill a Spherical Tank of Water with Given Parameters

    Hello, Can someone please give some hints on how to start this problem? I tried a few things but nothing is working! A spherical tank of water has a radius of 14 ft, with the center of the tank 50 ft above the ground. How much work will it take to fill the tank by pumping water up from...
  25. R

    Deriving Variation of Parameters for Systems

    1.Homework Statement We know the derivation of the method of variation of parameters for second order scalar differential. The task is to derive the method of variation of parameters for scalar equations using this approach: first convert the scalar equation into the first order system and...
  26. S

    System identification: suspension parameters

    I need to estimate the suspension parameters (i.e. spring stiffness, damping coefficient and so on). So I have measured the acceleration at the top and at the base of the suspension during ground excitation. I have used a random excitation. The matter is the problem is nonlinear due to air...
  27. ¡

    Calculating Decoupling Capacitor When Datasheets Don't Specify Parameters

    To calculate the value for a decoupling capacitor (Vdd pin to Vss), I use the formula I=\frac{C \cdot dv}{dt} But what do I do if I don't know the load capacitance? For example, I have a push/pull comparator whose output is connected directly to an input of a PIC mcu. The capacitance of...
  28. R

    Extension of Variation of Parameters to First Order Non-Linear ODE?

    The equation of motion of a rocket with mass depletion during ascent and subject to drag forces can be written as M(t) dV/dt = A - M(t)g - BV^2 (Eq. 1) with initial condition V(t=0) = 0 (V is velocity and t is time) Let us assume a linear mass depletion according to...
  29. S

    Approaching a Step Function Problem with Variation of Parameters

    Homework Statement Hello, i have a small problem regarding this questions, If the function vs(t) is a function for t>=0, i can solve thus no problem (we are required to solve using variation of parameters). now i have a small problem, its not about how to solve it ,but how to approach...
  30. C

    Easily modifying BJT parameters in LTSpice?

    I've created a multistage amplifier in LTSpice IV and want to use actual measured hfe (Beta) values for each of the transistors, though I can't find an easy way to modify them. I could modify their library values in notepad, but I am using the same transistor model for a few of the stages and...
  31. A

    Estimating Parameters for Logistic Equation

    Homework Statement logistic equation: dN/dt = rN(1-N/K) Find estimates for the unknown parameters r and K. The Attempt at a Solution I have solved the logistic model to get N(t) and I have a table of data which lists time and corresponding N values. I tried to just choose 2 times...
  32. H

    Parameters for Root Locus Method using Lead Compensator

    Hi everyone, I would please like some suggestions regarding where my error is, designing a lead compensator with the root locus method for a unity feedback control system where G = [12.5] / [2.5 1 2500]. I want to set the overshoot zeta = 0.5 for an overshoot of 16%, and settling time Ts =...
  33. A

    Differential equations - variation of parameters

    Homework Statement Find a particular solution using variation of parameters. y'' + 3y' + 2y = 4e^x Homework Equations yp = -y1 * INT (y2f(x)/W[y1,y2]) dx + y2 * INT (y1f(x)/W[y1,y2]) dx The Attempt at a Solution So, first I find the homogeneous solution, correct? r2 + 3r + 2 = 0, so...
  34. C

    Quick Question on Variation of Parameters Differential Equations

    Homework Statement What do you do if one of the roots to the characteristic equation of a differential equation is zero when using variation of parameters? Homework Equations The Attempt at a Solution The problem I encountered this in is y" - y' = 4t Characteristic equation r2 - r = 0 so...
  35. J

    Practical control parameters for UAV?

    Hi, Anyone has had experience with UAV control/signal design can tell me what is the typical flight speed (surveillance UAV), control range, link speed and control delay like? (Sorry, I am not a very good engineering student, furthermore control and signal not my discipline... I can only...
  36. M

    Can't read parameters from file

    Homework Statement I'm trying to read parameters from a text file (format below) but actually my function didn't receive any parameters from read file function. Number_of_points 80 Distance 10.0 Time_step 0.05 Velocity 5.0 Diff_coeff 50.0 Homework Equations The Attempt at a...
  37. N

    Determining parameters of a function from its outputs

    Suppose that I have a function f(a,b,c,d) = g, where {a,b,c,d} are four independent variables and g is the dependent variable. Now let's say that I evaluate the function four times, each time using different inputs, and the function produces four different outputs: f(a_1,b_1,c_1,d_1) = g_1...
  38. Telemachus

    Finding Force on Rope: Trigonometry & Parameters

    Homework Statement Hi there. Where, I got this exercise. I have a ball attached to an ideal rope with longitude L, moving on a circle with speed V on a circular trajectory with radius R over an horizontal plane. So it asks me to express the subjected force over the rope as a function of the...
  39. T

    Optimizing Transformer Parameters for Efficient Substation Performance | Tims

    Hi All, I am required to assume some parameters for my research, For a new transformer worth $100 million for a substation, what likely could be sensible for these parameters? Nominal Capacity? (Example 10^5 KW) Average Repair Cost? ($1 million ?) Unsupplied energy cost? ($3 kWh ?)...
  40. Saladsamurai

    Variation of Parameters on a 1st Order DE

    Homework Statement Solve xy' - y = x3 (1) by using variation of parameters. The Attempt at a Solution Solving the homogeneous version of (1) gives yh = c1x Now we are to seek yp = A(x)*x (2) from (2) y'2 = A'*x +A plugging into (1) we have: x[A'*x + A] - Ax = x3...
  41. W

    Plot of Ginzburg-Landau parameters

    A while back, I saw a plot that compared the Ginzburg-Landau parameters of different superconductors. The x-axis was the GL parameter and the y-axis was magnetization or field or something of that nature. I would like to find this figure again to use in a presentation. Can anybody point me to...
  42. Y

    Mathematica Optimizing parameters without specifying them (Mathematica)

    I use NMinimize to optimize a likelihood function. The number of parameters included depends on the dimensions of a vector I pass. I would like to have Mathematica check the dimensions of the vector, declare the correct number of parameters for me, and then solve for them. Right now, I have...
  43. J

    Mathematica and Variation of Parameters

    Hi, I was solving the following second order ODE: http://www.texify.com/img/%5CLARGE%5C%21x%5E2%20y%5E%27%27-5xy%5E%27%2B5y%3Dx%5E6%20sinx.gif I used variation of parameters and found this solution...
  44. A

    Acoustic Parameters for Passive Noise Control

    1. Homework Statement Actually I am doing a research project about Noise Isolation. I took my college cafeteria as an example and I was provided with a Noise Simulation software( Soundplan). There I can work mainly with the SPL and the absortion coefficients. I found another software ( EASE)...
  45. R

    Plate deflection theory vs FEA: same problem, same parameters, different results

    Hello. I'm trying to simulate a plate deflection using finite element analysis software ALGOR. Previously I made analytical calculations and I got the maximum deflection like this: (My plate is simply supported on all edges, so I used Navier's Method. Got the theory from Szilard's Theories and...
  46. B

    Statistics, Parameters, and the Central Limit Theorem

    Hi, everyone: I am teaching an intro. stats course, and I want to find a convincing explanation of how we can "reasonably" estimate a population parameter by taking random samples. Given that the course is introductory, I cannot do a proof of the CLT. Specifically, what has seemed...
  47. A

    Calculating Curvature of 3D Hyperboloid - Parameters & Extrinsic Curvature

    How can I calculate the curvature of a 3D hyperboloid? I mean, what parameters do I need to calculate the intrinsic curvature? I guess to calculate the extrinsic curvature as seen from a 4D space I would just need a curvature radius, right? Thanks
  48. Rasalhague

    Curves & Parameters on a Manifold M

    These definitions seem to suggest that the same subset of M could be the range/image/arc of many different curves, each having a different parameter. Is that right, or should I think of a curve as an equivalence class of such maps?
  49. S

    Parameters to design a breaking system

    wat are all the parameters should i consider in adopting a breaking system for a 796cc single seat formula car and can u suggest some cars breaking system
  50. E

    Determining parameters for trapped air in contact with water.

    Hi everyone, I need to evaluate parameters (heat capacity, density and thermal conductivity) for some very humid air. I know the parameters for both dry air and water vapor. So I suppose the parameters I need will just be a linear combination of the other parameters, with a coefficient...
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