Parameters Definition and 535 Threads

I came across the following statements about renormalisation in the context of Compton scattering ##(\gamma q \rightarrow \gamma q##) and its QCD corrections: 1) 'The bare and renormalised couplings are equal at ##\mathcal O(\alpha_s^0)##, thus the renormalisation of the strong coupling in a...

Hi guys! I need your help! 1. Homework Statement Use the function of Lennard-Jones V (R) = ε [(σ / R)12 - (σ / R)6] as model for the adiabatic potential energy in function of the separation between the 11B boron and nitrogen nuclei 14N. You determine the parameters ε and σ to reproduce the...

I'm trying to plot the density parameters against redshift in Python, so I suppose this is kind of a cross over of programming and physics. I've been given the following two equations in order to do so $$r(z) = \lambda_H \int_{0}^{z} \frac{dz'}{E(z')}$$ $$E(z) = \frac{H(z)}{H_0} = \sqrt...

Homework Statement Use the method of variation of parameters to find a particular solution Homework Equations https://flic.kr/p/NqhtyQ The Attempt at a Solution https://flic.kr/p/NicCbN [/B] Can some find my mistake? The answer is just suplosed to be - 2/3te^-t[/B]

HI, I am looking to find a table of galaxies, their masses, types, black hole mass and dark matter content. Does anyone know if such a place exists anywhere on the internet? I'm trained in physics but is not a physicist - more a hobbyist. Any suggestion that you might have will be greatly...

Homework Statement Find for what real parameters the line ##r## is parallel to the plane ##\pi##. ##r: \begin{cases} x - 3y + 3 = 0 \\ 2y + z - 5 = 0 \end{cases}## ##\pi : 6x - (a - 1)y + 3az - 11 = 0## Homework EquationsThe Attempt at a Solution So, the only method I know is to put the three...

The voltage waveform of the PLL circuit VCOin is shown(The PLL can lock).I need to get the stable voltage.If I change C18 from 0.1uF to 10uF, PLL cann't lock phase,the VCOin is always 5V,How to select C18/R5/R6 of the filter.How to calculate?

Homework Statement 1. a) Contrast the relative performance of each op-amp in terms of these parameters and state how they compare to that of the ideal op-amp. b) TABLE B gives two descriptions of operational amplifiers. State, with justifications, which description most closely matches the...

One way that I often write recursive functions in my work is by having an optional parameter that is used for all calls after the first. For example, here's how I might implement the classic "Find the largest palindrome in a given string" interview-type problem: using System; public static...

Hello! I am yet very weak in statistics, but I am learning some basic finance, and this requires to create regression. Please, take a look at attached files - one excel that contains the results of regression and one screen shot of the window of StatPlus that I have to fill in. Before using my...

Kreyszig Advanced Engineering Mathematics shows the variation of parameter method for a system of first order ODE: \underline{y}' = \underline{A}(x)\underline{y} + \underline{g}(x) The particular solution is: \underline{y}_p = \underline{Y}(x)\underline{u}(x) where \underline{Y}(x) is the...

Homework Statement Compute the following parameters of the final image formed by the lens system shown in the figure below a) position b) size c) nature (Real, Virtual, Upright, Inverted, Etc.) Homework EquationsThe Attempt at a Solution i am kind of lost at where to begin...

Let ##\mu: \mathbb{R}\to \mathbb{R}##, ##f: \mathbb{R}\to \mathbb{R}##, and ##r: \mathbb{R}\to [1, \infty)## be bounded measurable functions (which may be discontinuous). I'm interested in the function ##v:\mathbb{R}\to\mathbb{R}## given by ##v(x) = \mathbb E \left[ \int_0^\infty e^{-\int_0^t...

Hi, I've defined engine power requirements based on driving dynamics, but am not sure how to extend this to engine parameters. From design requirements, I've fixed my gear ratios, and hence can determine how much power and torque is required from the engine at a particular speed. I want to then...

Good day every one! Based on my research as you increased the temperature, the grain size become bigger and the thickness decreased, but in some paper, thickness increased. The effects of annealing temperature is almost the same to the temperature. But if you will considering doping for...

Hey guys, recently I have do some self-study on the ground response parameters on cohesive and cohesionless soil.. I made some deduction but I cannot confirm if it is correct or not, thus needing the help from the PF community. The deduction is as follows; I need explanation for the occurrence...

I am trying to develop a Ventury https://www.physicsforums.com/javascript: Pump using Compressed Air a d Motive Fluid and Suction Fluid is Water from Shallow Well. Compressed Air parameter is 6CFM Air at 7 bar using 2hp Motor & Compressor set, and required Suction Lift is about 5m. Discharge...

So using the property U†U=1 I was able to get ∑uikujk*=δij where the sum is over k=1,...,n and u is a complex number. from this you get n equations when i=j. If i≠j I get n(n-1) equations but in the notes I'm reading from it...

I was going to try and do an animation of stars orbiting Sagittarius A* but can't seem to find any useful data for it. The Wikipedia page has some data https://en.m.wikipedia.org/wiki/Sagittarius_A* and was trying to reconcile this with https://en.m.wikipedia.org/wiki/Orbital_elements since I...

Hello All, I only have a vary basic understanding of physical concepts so please bear with me. I'm an object with mass greater than 0, a maximum speed, a maximum rate of acceleration and deceleration. Suppose I want to travel from point A to point B. The path is chosen for me and it leads...

i was trying to get a particular solution of a 3rd order ODE using the variation of parameters method the homogeneous solution is yh = c1 e-x + c2 ex + c3 e2x the particular solution is yp=y1u1+y2u2+y3u3 as u1=∫ (w1 g(x) /w) dx , u2=∫ (w2 g(x) /w) dx , u3=∫ (w3 g(x) /w) dx w =...

Hi, I'm doing a project on galaxy clustering and in a lot of papers where they list the cosmological parameters they've used, they list σ8 and ns. Can anyone quickly tell me what these parameters are referring to? Thanks

Hi I'm looking to design a 4 bar compound linkage. I know how torque, force, power and angular velocity are transferred on four bar mechanisms. Could someone help me with compound four bar calculations? http://i66.tinypic.com/2jg6z9t.jpg The lower arrow shoes the input torque. I need to design...

Use the variation of parameters method to find a general solution of $x^{2}y''+xy'-9y=48x^{5}$ $m^{2}-9=0$ $(m+3)(m-3)=0$ $m=3,-3$ $y_{h}=c_{1}x^{-3}+c_{2}x^{3}$ $W=6/x$ Don't really know how to do wronskian with latex so i didnt include the steps. But i need help with the rest of this. i...

Homework Statement Homework EquationsThe Attempt at a Solution Stator Line voltage 220 164 112 88 42 Stator Line Current 6.8 5.4 3.9 3.8 3.7 Stator power 470 360 278 244 232 By plotting a suitable graph from these results, determine the total of windage and friction...

How to write a code can determine optimum over relaxation parameters? Also, is there a code for getting to solve matrix with successive over relaxation method?

Hi All, I am struggling with minimization(maximization) problems which needs to be solved graphically but they have unknown parameter in objective function: For example: f = 2x_1 + \lambda x_2(min) for conditions: -x_1 + x_2 \leq 3 x_1 + 2x_2 \leq 12 3x_1 -x_2 \leq 15 x_i \geq 0 More than...

Hi, So we're doing this Lab on Transient reactance of a synch generator and I'm reading Sarma's classic: Electric Machines Steady-state theory and Dynamic performance p. 474-479 But I can't see how to get the actual exponential time constants for the sub-transient and transient reactances? Thanks

This is not only a question strictly about mathematics, but in science or any other quantitative field in which there is an integration - or a summation that is like a discrete integration. [ A ] the parameter that is considered the input variable for the integration/summati - i.e., the x of dx...

Homework Statement y'' + y = tan2x The Attempt at a Solution yh = c1sinx + c2cosx yp = -y1 ∫ (y2r/W) dx + y2 ∫ (y1r/W) dx r = tan2x y1 = sinx y2 = cosx W = 1 I'm using integration by parts, but I've realized that the trig functions repeat (trivial). Is there another way to solve this...

Homework Statement Find the general solution of the following equation: u(t): u' = u/t + 2t Homework Equations y' + p(x)y = Q(x)....(1) yeI = ∫ dx eIQ(x) + constant.....(2) The Attempt at a Solution I rearranged the equation to give: u' - u/t = 2t Then I considered the following...

Given a ODE like this: y''(t) - (a + b) y'(t) + (a b) y(t) = x(t) The general solution is: y(t) = A exp(a t) + B exp(b t) + u(t) exp(a t) + v(t) exp(b t) So, for determine u(t) and v(t), is used the method of variation of parameters: \begin{bmatrix} u'(t)\\ v'(t)\\ \end{bmatrix} =...

In the EveryCircuit, the element diode has all these parameters: And I don't know what each parameters means... The program don't inform anything, so, what these parameters means? I searched for a manual in the google and don't exist too... And now? Exist so much elements whose with so much...

Hi, 1. Homework Statement C : ℝ→ℝ3 given by C(t)= ( 1/2 [ (1+k)/(1-k) cos((1-k)t) - (1-k)/(1+k) cos((1+k)t) ] ; 1/2 [ (1+k)/(1-k) sin((1-k)t) - (1-k)/(1+k) sin((1+k)t) ] ) with 0<|k|<1 Show that C(t) is an epitrocoid and find R, r and d according to k Homework Equations Parametrization of...

I am not sure that I understand the following: http://www.cplusplus.com/doc/tutorial/pointers/ Why would someone pass an input to a function that he/she doesn't want to modify? And suppose that I want to do that, for example a function that runs a loop over N events determined within the main...

A man with one watch knows what time it is. A man with two watches is never sure. I've seen several combinations of 'standard' λCDM parameters. The NED search site has the three year WMAP as the default and you can select the 5 year as an option. I've seen several papers on the Plank study...

This question is mostly about group theory but I would like to understand it in the context of qubits rotating in a Bloch Sphere. What my understanding of things are right now: In the rotation Lie Group ##SO(3)##, we have three free parameters (##\frac{n(n-1)}{2}##), and this is also why we end...

Hello, I have data for optimization that contains different values of 4 different parameters, and the respective function value based on them. I want to find the maximum of this function, while making sure it's a "stable" maximum, i.e., for nearby parameters, the value of the function shouldn't...

Given a generic second order ODE, normalized that equals to g(x) I saw in a video that, when writing the Wronskian, W1 and W2, for writing W1 you had to "delete" the first column if the Determinant and replace it with zeroes until you reach the end, where you replace it with g(x) Is this always...

Hello I have a question about design oscillator with linear small S parameters.If you assume I use a Common emitter configuration and put my resonator at input port (Base/Emitter). After I select a Gama(G) in unstable region in input smith chart plane(for example Gama(G)=A<B (for example A=1))...

I was wondering if anyone has any knowledge of any work that has been done, to use machine learning methods to try to learn parameters good for a physics simulation. Or if anyone has any insight about how this can be done.

Hello I want to know it we have common Emitter s parameters how can we extract s parameters of common base configuration?if there is no problem give me some examples in converting Thank you

Hello everybody, Sorry to ask you something that may be easy for you but I'm stuck. For example I have 2 images (size 2056x2056). One image of reference and the other is the same rotated from -90degrees. Using a program with keypoints, it gives me a transform matrix : a=2.056884522e+03...

Homework Statement Hello i am trying to write the Stokes parameters as the amplitude of the averaged EM-wave We know the stokes parameters are {I,M,C,S} or {S0,S1,S2,S3} thus a column vector. And S0 is defined as S0=<E2x0>T+<E2y0>T S0 i understand how it was derived since Filter 0 is an...

Hallo math helpers , i am trying to understand how one could solve the following integrall: $$\int_a^b \mathcal{N}(f(x_1,...,x_n,t),g(x_1,...,x_n,t)) dt$$, where $$\mathcal{N}$$ is the normal distribution, and $$f(x_1,...,x_n,t): \mathbb{R}^{n+1} \rightarrow \mathbb{R}$$, $$g(x_1,...,x_n,t)...

Homework Statement In a course I am studying, I have been asked to calculate the distributed parameters of a line whose Pi model has been provided. I simply quote the question here for clarity of my question: Homework Equations C = \frac{{2\pi \varepsilon }}{{\ln \frac{b}{a}}} R =...

Hi, I am asked to determine the Line Regulation and Load Regulation based on the attached datasheet, using the test circuit parameters listed there. Homework Statement Homework EquationsThe Attempt at a Solution Line Regulation is defined as ΔVo/ΔVI whereas Load Regulation is defined thus...

Can someone verify that my answer is correct ? Thanks in advance. Use Variation of Parameters to find a particular solution to $y'' - y = e^t$ Solution: $y_p = \frac{1}{2}te^t - \frac{1}{4} e^t$

Hi. There is one thing I don't understand: Why do stoke's parameters and all the Jones calculus business apply only to incoherent light? I don't understand how it can work on incoherent light, while fail to work on e.g. monochromatic light. Or am I just confused? All answers appreciated.

Hey, PF: If I have a function ##f(x)## where ##x## is itself a function of another variable (say time), is the following then true? $$f(x)=f(x(t))=f(t)$$ I ask this because if I have the following system of differential equations $$\frac{dA}{dt}=-Bb$$ $$\frac{dB}{dt}=-Aa$$ where litte ##a##...