What is Psd: Definition and 25 Discussions

The PSD Bankengruppe is a German cooperative banking group consisting of 14 autonomous and independent financial institutions. The business model of the PSD banks is a combination of regional direct and affiliated bank. It provides retail banking services via internet, telephone, e-mail, mail and fax or at local branches, it only provides services to retail clients and does not offer banking to self-employed and businesses.
The name PSD originated from the former name Post-Spar- und Darlehnsverein (post-, saving- and loan association). The Post-Spar- und Darlehnsverein banks originally provided financial services by postal clerks only and were assigned to the areas by the post office. They are particularly connected to their area and predominantly operate at a local level.
All PSD banks have a legal structure of a listed cooperative and are therefore cooperative banks. PSD banks are purely private customer banks. Today, with one exception, all 14 PSD banks are in the universal bank business. The PSD banks are part of the Verband der PSD Banken e. V. (union of PSD banks) which is located in Bonn. Besides other services the union acts as auditing association for the banks. All PSD banks are affiliated to the protection scheme of the Bundesverband der Deutschen Volksbanken und Raiffeisenbanken (National Association of German Cooperative Banks) (BVR).

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1. Why is this method valid to show function is PSD?

Hi, I was looking at the following example, and I cannot really understand the justification for why this function is positive semi-definite. Example Problem: We are looking at the function: ## f(x, y) = \frac{x^2}{y}, x \in \mathbb{R} , y > 0 ##. Is this function positive semi-definite...
2. I Linearity of power spectral density calculations

I have a question related to linearity of power spectral density calculation. Suppose I have a time series, divided into some epochs. If I compute PSD by Welch's method with a time window equal to the length of an epoch and without any overlap, I obtain this result: If I calculate the...
3. Units For a Power Spectral Density (PSD)

(Just as clarification on what I am doing, I am attempting to use MATLAB to create PSD plots of time series from pressure and accelerometer sensors. Wave gauge sensors might still be helpful for me. I did not discuss accelerometer sensors in the post but maybe I could figure it out if I get the...
4. Automotive Random Vibration and PSD spectrum profiles

I am starting work on structural durability area for after treatment systems and deal with Random Vibration and PSD profiles quite often. However there are few fundamental questions about PSD profiles that I could not get answer to after a lot of search on internet. So finally decided to write...
5. Peak-hold equivalent amplitude for transient vibration

I have a question regarding transient vibration data I received that was processed into a peak-hold equivalent amplitude (units = g). I have come across peak-hold before which is a type of "averaging" that retains the highest values from each estimate in random vibration overlap processing and...
6. Looking for tighter bound on symmetric PSD matrices products

Homework Statement Let K and L be symmetric PSD matrices of size N*N, with all entries in [0,1]. Let i be any number in 1...N and K’, L’ be two new symmetric PSD matrices, each with only row i and column i different from K and L. I would like to obtain an upper bound of the equation below...
7. Why Use PSD Curves in Random Vibration Analysis?

In the analysis of Random vibration, we use the PSD curves as the input, I am confused as to why we simply don't use acceleration versus time graph but instead convert it into g^2/Hz and Hz.
8. Power Spectral Density Confusion

Hi, I am working on a project and came across a conceptual roadblock. I am working with a PSD, let's say the units are V^2/Hz. I choose a dF based on how many sine tones I want in the time signal I am going to create. I sample the PSD curve at my frequency bin locations; so I have both my...
9. Implementing the PSD from its definition

I would be grateful for some direction on this. I wish to implement the following - Given a deterministic signal (the feedback signal of a closed-loop stable system) I would like to plot the power spectral density. The definition I am working with is this: Implementation (MATLAB): %...
10. Fatigue Vibration with Fe-Safe

Hello everybody , I am student in mechanical enginnering. I have to evaluate the solution Fe-Safe. i am working on two subjects: Harmonic and PSD Vibrations. The modal analysis are done in Abaqus. I would like to understand how Fe-Safe computes Life Fatigue in case of harmonic analysis. What...
11. Unraveling the Mystery of N_{0} in PSD of Noise

I know the power spectral density, PSD, of noise is: \frac{N_{0}}{2} from where do we get N_{0} ? Is that the RMS value of the noise? Is it related to noise power and noise temperature as in the following: N=kTB, where k = Boltzmann’s constant, T is noise temperature, and B is...
12. Determining PSD of 1uaternary (4-ary) line code

Homework Statement Ok So this is an example from my text. I am having trouble following a portion of it and was curious if anyone could shed some light on it. I've typed most of it and posted a screen shot of the second portion since there is a table involved. Determine the PSD of the...
13. ISO 8608: get the time history from PSD of road roughness?

Hi all, I have a vehicle multibody model and I want to excite it in different conditions. So I'm thinking to use the PSD or road roughness as reported in the ISO 8608. What I don't understand is, how can I get an equivalent time history of the vertical road displacement from the PSD? thanks
14. Confused about autocorrelation and PSD

I am confused a bit :confused:. I read in a paper that the following property holds, but can't find where it comes from. \mathsf{E}\left[X(\omega)X^*(\omega')\right]=2\pi\delta(\omega-\omega')S_{XX}(\omega) it says that the expected value of the Fourier transformed signal is proportional...
15. How to find a probability density function (psd)?

This might not be in the right place but here it goes: Homework Statement A given periodic function in time is given u(t). I must compute the probability density function that describes u. u(t) = A sin (2π / T t + ψ) A and ψ are constants. T is the period. t is time. Homework EquationsThe...
16. MHB More questions on psd and pd of matrices

First question: If A is pd, then A^-1 is pd. Outline of answer: If A is pd, then there exists a nonsingular matrix P st A=P'P Then A^-1 = (P'P)^-1 = (P^-1) * (P^-1)' = (P^-1)' * (P^-1) 3. If (P^-1)' * (P^-1), then there exists a A^-1 that is positive definite Second question: If...
17. MATLAB Matlab: How to get the PSD of a signal?

I'm trying to plot the PSD of a signal, I did it using the fft function but I was wondering if there is another direct method?
18. Measured PSD: why peaks are multiples of a frequency?

Hi all, I have a suspension system that is mounted in a vehicle and I must evaluate its behaviour. So I have measured the acceleration at the suspended mass and at the base. Since I haven't a bench I was obbliged to test it during vehicle driving. All signal are sampled at 500Hz. In the next...
19. Optical scattering: Converting BRDF to PSD

edit: the TeX is still being screwy, not putting the equations in the right places. stay tuned. editII: fixed, I think. Homework Statement I'm working on converting a BRDF to a PSD, S(fx,fy). Homework Equations In the book 'optical scatter: measurement and analysis', the BRDF is given as...
20. Can a PSD Matrix Be Expressed as a Sum of Structurally Similar Matrices?

Is it possible to express a n-by-n positive semi-definite matrix (A) in terms of a sum of n terms of something, i.e. A = B1+B2+...+Bn, where each Bi has similar structure? Thanks!
21. A question on PSD (positive semidefinite) completion

Please help me to solve this question: Let A=\left[\begin{array}{ccccccc} |a_0|^2 &a_0\bar{a}_1 &a_0\bar{a}_2 &0 &a_0\bar{a}_3 &0&0\\ \bar{a}_0a_1 &|a_1|^2 & c &0 &a_1\bar{a}_3 &0&0\\ \bar{a}_0a_2 &\bar{c} &|a_2|^2...
22. A condition on principle minors of a symmetric Positive semidefinite (PSD) matrix

Hi everyone, Let A=(a_{ij}) be a symmetric (i.e., over reals) PSD matrix. Then is the following correct? "If any principle minor ( \ne A ) be zero, then all principle minor contained in this minor should also be zero". I can not prove or disprove it..any help? By the way how...
23. Accelerometer Noise PSD to Velocity Random Walk

I have the intrinsic noise PSD spec for Honeywell's QA3000 accels, and I need to find the velocity random walk due to noise to show that I'm within my allowable. The PSD is given in units of g^2/Hz vs Hz. I'm given a velocity random walk due to noise spec of 15 (micro-m/s)/rt(s) that I must be...
24. 2 known signals, 1 PSD: extract components with same phase.

As stated in title: I have full knowledge of the 2 signals. They have the same Power Spectral Density. However, only certain components of the 2 signals have the same phase. Is there any way of extracting these components, or at least their PSD functions? Is this doable at all? The phase I...
25. Condition on minors to be Positive Semidefinite (PSD)

Hi everyone, I know that for a hermitian matrix to be PSD it is necessary that every principal minor [i.e, the minors obtained by deleting all the last i rows and columns for all i=(n-1)(-1)0]. I want to know if it is necessary that all minors of order>=2 be non-negative. Particularly, for...