Distribution Definition and 1000 Threads

  1. D

    A Normalization of Radial Distribution Function

    Hello all, I have a Radial Distribution Function in which the y-axis ie., g(r) value goes up to 40. But the other atoms values for g(r) are, say within 5. So when i plot these two it is difficult to see the smaller graph. So how do i normalize these value..?? I have attached an image. Any...
  2. Frankenstein19

    Equilibrium distribution of a solvent in two immiscible solvents

    Homework Statement I need to find the distribution coefficients for acetic acid of various concentrations in a ether/water system, but I'm not too sure of my calculations Homework Equations To get the concentrations of acetic acid in the aqueous phase I took the ([average concentration of...
  3. iamvksaini

    Flow Quality Impact on airfoil pressure distribution

    I have collected velocity data for a 3-D grid of test section of a low speed wind tunnel.I have tested airfoils for pressure distribution in the same test section for similar free stream conditions. How do I calculate the impact of flow quality in the test section on the test results of pressure...
  4. D

    A Estimation error from estimation quantile of normal distribution

    Hi guys, For my (master) project I am trying to find the probability that a random variable, which is normally distributed, exceeds a quantile that is estimated by a limited number of observations. See attached for my attempt. - Is it correct? - How to incorporate the fact that the mean and...
  5. Abhimessi10

    Charge distribution on concentric spheres

    Homework Statement Two thin conducting spherical shells have radii R1 and R2.Outer shell is charged to q and inner shell earthed.Find charge appearing on both the shells. Homework Equations The Attempt at a Solution Isnt the charge on inner shell 0 and charge on outer shell remains Q as it...
  6. Vital

    I Understanding part of the multinomial formula

    Hello. I am trying to decipher the formula, making sure I understand what exactly is going on in each part of the expression. I will be grateful for your guidance, corrections and help. Below I show the formula and the example for only 3 possible outcomes (in general it would be k) \(p =...
  7. T

    Expected bounds of a continuous bi-variate distribution

    Homework Statement [/B] ##-1\leq\alpha\leq 1## ##f(y_1,y_2)=[1-\alpha\{(1-2e^{-y_1})(1-2e^{-y_2})\}]e^{-y_1-y_2}, 0\leq y_1, 0\leq y_2## and ##0## otherwise. Find ##V(Y_1-Y_2)##. Within what limits would you expect ##Y_1-Y_2## to fall? Homework Equations N/A The Attempt at a Solution...
  8. S

    Radial Distribution Function (RDF) versus Radial component

    Homework Statement For the RDF, we take the square of the radial component multiplied by 4pi r2 (the surface area of a sphere) and this gives us the probability density of finding an electron r distance away. Whats the point in multiplying it by r2? Homework Equations RDF= r2[R(r)]2 The...
  9. Kairos

    Misinterpretation of the Maxwell velocity distribution?

    I suddenly have a problem with the famous Maxwell velocity distribution. The maximum of this bell-shaped curve is commonly interpreted as the most probable velocity for a particle (see for instance https://en.wikipedia.org/wiki/Maxwell%E2%80%93Boltzmann_distribution: "The most probable speed...
  10. A

    Electric field distribution in the brain

    I have a PhD in Molecular Neuroscience but am working on something that requires knowledge of electric field distribution in the brain. I understand that electric field intensity (V/cm) is E=(V1-V2)/d in a theoretical model (between 2 infinite plates, that are parallel and equidistant through a...
  11. A

    What is the Role of Electric Field Distribution in the Brain?

    Hi, I have a PhD in Molecular Neuroscience but am currently working on something that requires a deeper understanding of electric field distribution in the brain. I joined the forum hoping to be able to discuss this topic with a fellow scientist who specializes in this field.
  12. R

    I Rayleigh distribution and the probability of a point

    Okay, so I just found out about the Rayleigh distribution being the radial distribution of a point composed of normal distributed cartesian components. And this is because of the area element, right? But how then can the joint density of the cartesian component's distributions equal that of the...
  13. Aleoa

    I Maxwell and The distribution of velocities in a gas

    In the first volume of his lectures (cap 6-4) Feynman presents Maxwell's distribution of velocities of the molecules in a gas. And, referring to the PDF graph he says: "If we consider the molecules in a typical container (with a volume of, say, one liter), then there are a very large number N...
  14. S

    I Distribution of nucleons in the nuclei

    What does this diagram tell us about the distribution of nucleons in the nuclei? - The diagram is from Krane Introductory Nuclear Physics I know that nucleons don't congregate around a central part of a nucleus, but instead have a constant distribution throughout. i.e. The number of nucleons...
  15. T

    MHB Question about Bayesian Inference, Posterior Distribution

    I have a posterior probability of p_i which is based on a Beta prior and some data from a binomial distribution: I have another procedure: $P(E)=\prod_{i \in I} p_i^{k_i}(1-p_i)^{1-k_i}$ which gives me the probability of a specific event of successes and failures for the set of $I$ in a...
  16. malawi_glenn

    I Probability distribution of random events

    Hi Imagine we have a lottery, with chance of winning 1 in 1000 (1/1000). I have made computer simulations in order to find confidence levels for winning. At 1000 bought lottery tickets, the confidence of winning is 64.1% and 2000 bought lottery tickets the confidence of winning is 87.1% By...
  17. José Ricardo

    How does the Radial Distribution Function compare for 1s and 2s orbitals?

    Homework Statement Use a (simplified) graph to compare the maximum probability (electron density) of the Radial Distribution Function for the 1s and 2s orbitals. Homework Equations xxx The Attempt at a Solution The rest I don't how to solve.[/B]
  18. N

    A Two Bernoulli distribution- test hypothesis for biased coins

    I'm simplifying a research question that I have at work. Assuming I have 2 coins each with a different probability of head, let's call heads a success (p). Those are biased coins each with a different p, and I do not know the probability of success of each coin, but I do got a sample: Coin 1 -...
  19. W

    I Distribution of ratio std Normal and sqrt chi squared

    Hi all, I am trying to understand two things from a paper The ratio of a standard normal by the square root of a a chi squared divided by its df ( degrees of freedom) is a t distribution. So 1) What is the dist of square root of Chi squared? I know a normal squared is a chi squared, but a chi...
  20. Vital

    I T-distribution, standard error - how to interpret

    Hello. Math is not my strongest part, yet, so I will be very grateful for your help and for giving the answer in sort of "plain" English, meaning that it will be great if you don't go too deep into the rabbit hole using difficult terminology, as these distribution issues are truly difficult for...
  21. uzi kiko

    A 2 samples T test in case of non-normal distribution

    Hi All I made an experiment where I measured the change of the impedance of a coil when I changed a environment parameter X times. For each change I collected ~20 samples. So I have a table with X lines that represent the number the change of the parameter and 20 columns that represent the...
  22. SchroedingersLion

    A Correlation functions - radial distribution function

    Greetings, I am about to start my master thesis in computational physics and I need to make myself familiar with correlation functions, in particular with the radial distribution function of a system of N identical particles. At Wiki, there is a short explanation of the definition of the...
  23. WeiShan Ng

    I Distribution of Position in classical & quantum case

    I am confused about the difference between the two In Griffith's 2.3 The Harmonic Oscillator, he superimposes the quantum distribution and classical distribution and says What I understand for quantum case is that ##|\Psi_{100} (x)|^2## gives the probability we will measure the particle...
  24. G

    Powerline cable count and engineering question (HV power distribution lines)

    I have seen that typically most 110Kv and 330Kv lines around my place have not 4 wires on them (3 phases and one neutral) but rather 7 wires on them, which I suppose is 3 phases x2 which probably means two cables for each phase and a common neutral wire at the top of each post. Now is my...
  25. J

    Questions about deriving the Maxwell-Boltzmann Distribution

    Hello, I was watching a video on the derivation of the Maxwell-Boltzmann distribution function which would eventually lead to: $$\frac{e^{-\beta \cdot \epsilon_i}}{\sum_{i=0}^n e^{-\beta \cdot \epsilon_i}}$$ To do this, initially, the number of possible permutations ##\Omega## of a total of...
  26. renec112

    Probability distribution momentum for particle

    Homework Statement A particle with mass m is moving on the x-axis and is described by ## \psi_b = \sqrt{b} \cdot e^{-b |x|}## Find the probability distribution for the particles momentum Homework Equations ## \Phi (p)= \frac{1}{\sqrt{2 \pi}} \int_{-\infty}^\infty \Psi(x,0) \cdot e^{-ipx} dx##...
  27. joyxx

    Why are transformers important to electric power distribution

    Homework Statement Give two reasons why transformers are an important part of the power distribution grid My lessons don't have any information regarding this topic. I have read everything in my lesson and can't find anything to answer this question. please help. thank you
  28. K

    Hydrostatic pressure distribution despite fluid motion

    Hello, in some exam questions I've looked at it is stated that the pressure distribution is hydrostatic, even though there is fluid motion. (In these cases the velocity has been constant over the section where the pressure is said to be hydrostatic). Is it really possible to assume that the...
  29. M

    MHB Which is the distribution of (X,Y) ?

    Hey! :o We have that $X$ and $Y$ follow the normal distribution $N(0,1)$ and are independent. Which is the distribution of $(X,Y)$ ? Which is the covariance table of $(X,Y)$ ? Is $(X,Y)$ related to the linear combination of $X$ and $Y$ ? (Wondering)
  30. L

    A Family of curves tangent to a smooth distribution of lines

    Hi, Given a smooth distribution of lines in R2, could we assert that there is a unique distribution of curves such that: - the family of curves "fill in" R2 completely - every curve is tangent at every point to one of the smooth distribution of lines
  31. B

    Find maximum number of ind. r.v. that follows distribution F

    Sorry for the abbreviation in the name, the title has a length limit. Homework Statement Let X be a r.v. with cumulative distribution function F(x) and density f(x) = F'(x). Find the probability density function of a) the maximum of n independent random variables all with cumulative...
  32. BWV

    I How does the distribution of elements change over time?

    Been reading basic stuff about the astrophysics behind the prevalence of various elements, curious at what rate this changes over time. The Milky Way is something like 14 billion years old. At first it was all H and He then heavier elements were created and distributed through supernovae...
  33. R

    I Deriving the Boltzmann distribution

    I was reading the derivation of Boltzmann distribution using the reservoir model. lets call the reservoir by index R and the tiny system by index A. In the derivation they proposed that the probability for being at energy e (for A) is proportional to the number of states in reservoir. I didn't...
  34. Telemachus

    I Fermi-Dirac distribution, when does it break?

    Well, the question is if the well known occupation distribution of the energy levels for fermions does break, which means when it is not valid anymore. The Fermi-Dirac distribution reads: ##\displaystyle f_{FD}(E)=\frac{1}{exp\left({\frac{E-\mu}{k_B T}}\right)+1}## And gives the occupation...
  35. S

    I Boltzmann Distribution: Feynman's treatment of p-n junction

    In Vol III, 14-4 and 14-5 of the Feynman Lectures (http://www.feynmanlectures.caltech.edu/III_14.html), Feynman gives a discussion of the p-n junction, in which he derives the diode characteristic equation via a nice, simple and convincing application of the Boltzmann distribution to the...
  36. A

    B Angular distribution to energy distribution

    Hi! I wonder, in the case of elastic reactions with nuclear potential, how go from an angular distribution to an energy distribution? I have relationships on differential angular cross sections for neutron and proton elastic nuclear reations and I would like to transform them into differential...
  37. K

    Unbiased estimate of a parameter in the Rice distribution

    I am trying to estimate the amplitude of a real signal with a particular frequency and unknown phase. The signal is sampled at a frequency much higher than the Nyquist frequency for the signal. For simplicity, I take an FFT period which is a multiple of the signal period (which conveniently is a...
  38. J

    I Interpretation of the Fourier Transform of a Cauchy Distribution

    Hi, I'm struggling with a conceptual problem involving the Fourier transform of distributions. This could possibly have gone in Physics but I suspect what I'm not understanding is mathematical. The inverse Fourier transform of a Cauchy distribution, or Lorentian function, is an exponentially...
  39. A

    I Sampling from a multivariate Gaussian distribution

    I was watching a lecture on youtube about linear regression and there's a section where it had the statement below (written in purple). Does multiplying by sigma rotate the distribution to make it look like x - N(mew, sigma^2)? Mew in this case is 0 so it doesn't shift the distribution.
  40. A

    MHB Tail Behaviour of WIdom-Tracy distribution.

    I want to show that for $F_2(t):=\exp\bigg(-\int_t^\infty (x-t)q(x)^2dx\bigg)$, where $q(t)$ satisfies the ODE and the asymptotic relation respectively: $q''=tq+2q^3$ $q(t)\sim Ai(t)$ as $t\to \infty$; and $Ai(x)$ is Airy function such that for $x>0$...
  41. K

    Am I justified in using the binomial distribution?

    Homework Statement 12 non-distinguishable attacks from President Snow land in Panem’s 12 districts in a particular week. Assume the attacks are located randomly, with each configuration of attacks equally likely. What is the probability that some district had more than 1 attack? Homework...
  42. D

    Deriving Fermi-Dirac Distribution misunderstanding

    Homework Statement The actual question was deriving Bose-Einstein, but I got confused on the F-D example. I'm basically following the method given here. Homework Equations [All taken directly from the above link] Taylor series: The Attempt at a Solution So after that third equation...
  43. chwala

    Statistics: probability distribution problem

    Homework Statement two indepedent observations ##X_1## and ##X_2## are made up of the continuous random variable having the probability density function ## f(x)= 1/k##, and ## 0≤x≤k## find a. the cumulative distribution of ##X## b. Find the probability distribution of M, the...
  44. O

    Thermal neutron flux distribution in reflected core

    Hi, The figure given below was taken from "Nuclear Systems" by TODREAS and KAZIMI. it shows the effect of neutron reflector on the thermal neutron flux radial distribution. Is this correct? Because it does not show the extrapolated distance. It seems to me that the reflector, somehow...
  45. H

    Sampling Distribution Question

    I've added a screenshot (https://imgur.com/a/isQXZ) and the text below for your convenience. Please show steps if possible to help my understanding. Thank you. Consider a random variable that is Normally distributed, with population mean mu = E [X] and population variance sigma^2 = var [X]...
  46. quasarLie

    B Exploring Quasar Spectral Energy Distribution

    Hello, What do you think about this article? https://arxiv.org/abs/1502.05850 Why and how do we mesure the Spectral Energy Distribution for quasars? Thanks
  47. R

    Bayesian Probability Distributions

    Hi, I was having some trouble doing some bayesian probability problems and was wondering if I could get any help. I think I was able to get the first two but am confused on the last. If someone could please check my work to make sure I am correct and help me on the last question that would be...
  48. J

    Force Distribution: Understanding Points A, B, C & D - Joseph

    Could someone please help me understand how force is distributed across a plane as shown in the attached picture (I don't think I have the vocabulary to clearly describe the problem)? If 100 pounds/kg, for example, were placed point 1, what would the force be at points A, B, C and D? Would the...
  49. M

    Distribution of ions in a cylindrical container

    Homework Statement In a cylindrical container of radius ## R ## and height ## h \ll R ##, with long axis ## \hat{z} ##, in the presence of gravity acceleration ## \vec{g} = - g \vec{z} ## is contained a neutral ionized gas, whose ions can be described as material points with electric charge ##...
  50. W

    Electrostatics: Energy from a charge distribution

    Homework Statement [/B] For a straight wire of length 2L carrying a uniform charge density ##\lambda##, find 1) potential a distance z above the centre 2) electric field E at that point, 3) energy of this charge distribution Homework EquationsThe Attempt at a Solution 1) and 2) I can do...
Back
Top