Parameters Definition and 489 Threads

Homework Statement Solve for general solution with variation of parameter y'''(x) - y'(x) = x The Attempt at a Solution I initially looked at y'''(x) - y'(x) = x only and I foudn my answer to be y(x) = C_1e^{x} + C_2e^{-x} + 1 - x Now i looked through my book and it says it works for...

Hi all, I have a question regarding least-squares, and I'm certain I can't be the first one to encounter it, but I've had no luck searching the literature for a solution. Here it is: Say we have a non-linear least-squares optimisation problem. We have data points y_i and a model y(x_i;{\bf...

Hi guys, i can't seem to find the answer . A satellite in Earth orbit has a perigee velocity of 8 km=s and period of 2 hours. From this information, determine all the orbit parameters that you can. From those parameters, determine its altitude at perigee...

Does anyone know any sources (i.e. car manufacturers) that provide the exhaust air flow parameters for the some specific car engines? I need stats on various otto & diesel cycle engines (small compact car engines, large semi truck engines, etc.). When I say exhaust air flow parameters, I need to...

Homework Statement Several velocities, time, and length scales are useful in understanding what goes on inside engines. Make estimates of the following quantities for a 1.6-liter displacement four-cylinder spark-ignition engine, operating at wide-open throttle at 2500 rev/min. a. The mean...

Homework Statement The brake fuel conversion efficiency of an egine is 0.3. The mechanical efficiency is 0.8. The combustion efficiency is 0.94. The heat losses to the coolant and oil are 60 kW. The fuel chemical energy entering the engine per unit time, (m_f * Q_HV), is 190 kW. What...

Given t^2 y'' -t(t+2)y' = (t+2)y= 2t^3 and y1= t, y2= te^t Find the particular solution- I ve worked the problem to [ -2t^2 -2t] by: -t * Integral [ 2t* te^t/ t^2e^t] + te^t * Integral [ 2t^2/ t^2e^t] whereas the book states that it is simply -2t^2. Can you guys tell me where I made...

Murnaghan equation for lattice parameters? Hi everybody... I'm trying to determine lattice constant (a) for BN by calculating the total energy for different values of a using ABINIT, then chose the one which correspond the minimum value of energy, Is this convenient way to determine a ...

Question basically asks to find the parameters of a transformer via an open circuit and closed circuit test. We were taught that for OCT, V = (I * cos(theta)) * R V = (I * sin(theta)) * X To find the core losses. This makes sense, since we are only using the component of the current that...

Homework Statement In feedback problems of amplifiers we often use H feedback in the voltage controlled voltage sources... The good thing about that is that they are connected in series parallel form and they are then to find the net h parameters we simply add the h parameters of the...

E/M waves can be polarized, presumably, by filtering either their electric or magnetic transverse vectors. What about matter waves? Can they be electrically or magnetically polarized? Can they be polarized with respect to spin, parity, or any other parameter? That's a lot of...

Hi there! I'm working on analyzing some data from an experiment, and you can see a graph of some of the results in the attached .jpg image. I've done both a linear and a quadratic fit on the data points, weighted to error bars (the red lines are the fits). I use percents in the graph, but I'd...

Homework Statement \mathbb{x'}= \begin{bmatrix} 1 & 1 \\ 4 & 1 \end{bmatrix} \mathbf{x} \ + \ \begin{bmatrix} 2e^{t} \\ -e^{t} \end{bmatrix} Find the general solution. Homework Equations The Attempt at a Solution Well i found the eigenvalues of the matrix That i'll call...

For example, mass spectrum can't vary because energy is conserved (locally). What's about other parameters? Could CKM angles be different in earlier époque? It could save the Sakharov’s mechanism, if CP violation was more intense during bareogenesis.

HI, I want to reproduce results from the article (attached). I need to get parameters of interaction between atoms of H2 and C6H6 for Morse equation. I easily got results of interation between MOLECULES H2 and C6H6, shown in Table S2 'The first-principles and Morse force field (eq.1)...'...

Hi there, first, I apologize for my poor English. I made a simulation model and get results from HFSS Model has a equivalent circuit like that.(1) I run that model and get pair of solutions 'frequency vs response' like S parameter for each frequency. So, with these results, is it possible to...

Greetings, Maybe I'm getting a little bit confused, but I'm looking for resources which explain how to update parameters of a Bayesian network as a result of observations. There are various inference methods, but unless I'm missing something here, these methods produce a posterior...

which parameters affect about friction? and why?

Homework Statement Hi I'm looking for an algorithm that can perform a fitting procedure on many curves simultaneously. Let's say, for example, that I have 3 exponential decay curves with 3 different decay times but they all share the same initial amplitude. So I have to find a fit for 4...

Homework Statement in a genetics situation, we have two variables, x1 and x2, such that both x1 and x2 >0, and x1+x2<1. we have: p1 = x12 p2 = x22 p3 = (1-x1-x2)2 p4 = 2x1x2 p5 = 2x1(1-x1-x2) p6 = 2x2(1-x1-x2) find the mles for x1 and x2. Homework Equations the answer (from the...

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...

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...

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...

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...

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...

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) +...

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...

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...

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...

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.

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...

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...

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...

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...

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...

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...

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...

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

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!

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

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?

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...

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...

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...

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...

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...

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...

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 =...

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...

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...