What is Reduction: Definition and 469 Discussions

Noise reduction is the process of removing noise from a signal. Noise reduction techniques exist for audio and images. Noise reduction algorithms may distort the signal to some degree.
All signal processing devices, both analog and digital, have traits that make them susceptible to noise. Noise can be random or white noise with an even frequency distribution, or frequency-dependent noise introduced by a device's mechanism or signal processing algorithms.
In electronic recording devices, a major type of noise is hiss created by random electron motion due to thermal agitation at all temperatures above absolute zero. These agitated electrons rapidly add and subtract from the voltage of the output signal and thus create detectable noise.
In the case of photographic film and magnetic tape, noise (both visible and audible) is introduced due to the grain structure of the medium. In photographic film, the size of the grains in the film determines the film's sensitivity, more sensitive film having larger sized grains. In magnetic tape, the larger the grains of the magnetic particles (usually ferric oxide or magnetite), the more prone the medium is to noise. To compensate for this, larger areas of film or magnetic tape may be used to lower the noise to an acceptable level.

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  1. T

    Electrolytic reduction of iron ore - Stoichiometry

    Homework Statement Calculate the maximum mass of aluminum that can be made from 408 tonnes of alumina, assuming that aluminum is produced by electrolysis. Homework Equations At the cathode: Al^{3+} (l) + 3e^{-} \Rightarrow Al (l). At the anode: O^{2-} (l) \Rightarrow O_2 (g) + 4e^{-}. Is...
  2. A

    Prove Reduction Formula for Integral: x(1-x^3)^n dx

    Homework Statement In= (the integral) x(1-x^3)^ndx Prove that (3n +2)In = 3nIn-1 + x^2(1 - x)^n Hence find In in terms of n The Attempt at a Solution I tried integration by parts (by letting u be (1-x^3)^n and got stuck after this: In = 1/2x^2(1-x^3)^n + (the...
  3. Y

    Oxidation reduction reactions

    balance the following oxidation reduction reactions. which is the oxidizing agent? reducing agent? ()my answer as balance a) P4 + Cl2 =(4)PCl5 reducing agent P, o agent Cl b) Sn2+ + Cu2+ = Sn4+ + Cu+ reducing agent...
  4. J

    Integral Calculus - reduction formula/formulae

    Hi everyone - first a thanks to all who helped me through differential calculus and limits etc - think I'm getting the hang of it... Anyway as you can probably guess the next topic is integration. I'm kinda stuck on the 'concept' of reduction formula. I've done the usual integration...
  5. haushofer

    What is the significance of the LSZ reduction formula in Srednicki's QFT book?

    Hi, a small question about the LSZ reduction formula, as treated in Srednicki's QFT book (chapter 5). He argues that in a QFT in a scalar theory with interactions you would like that <0|\phi(x)|0> = <0|\phi(0)|0> = 0 and <p|\phi(0)|0> = 1 For the first he argues that were...
  6. marcus

    Steve Carlip: Dimensional Reduction at Small Scale

    http://www.ift.uni.wroc.pl/~planckscale/lectures/1-Monday/1-Carlip.pdf Steve Carlip gave the first talk of a weeklong conference on Planck Scale physics that just ended July 4 (yesterday). The pdf of his slides is online. We here at PF have been discussing since 2005 from time to time the odd...
  7. A

    Calculating reduction in static temperature and pressure

    When air is induced into a gas turbine inlet, the increase in velocity of the air will lead to an associated reduction in static temperatue and static pressure. How do you calculate these, that is, reduced static temp and pressures, given only Mach number, gamma, and perhaps total pressure ...
  8. D

    Reduction of differential equations then numerical methods

    Homework Statement I have a function that attempts to imitate the internal forces of the cord used for bungee jumping. I have been told to resolve it using Runge-Kutta 1st order numerical aproximation, therefore i have to reduce it to a system of equations. The preffered Runge-Kutta method...
  9. X

    Organic Synthesis: Reduction of ketone to alcohol

    Hi. I was to plan and conduct the reduction of 4-t-butylcyclohexanone into 4-t-butylcyclohexanol using NaBH4 as reducing agent, MeOH as solvent, and NH4Cl. My question is about the use of NH4Cl. How does it act as a quenching agent? I've figured out that it acts as a quenching agent by removing...
  10. F

    Designing Double Reduction Gear Drive: Input RPM 730, Output RPM 85.7

    i have to design a double reduction gear drive using a spur gear pair.Input RPM is 730 and output RPM is 85.7. s The pinion teeth are 18 and the module is 3. The problem is that the input torque is 144Nm due to which i am getting a very high tangential velocity (Ft) which results in a higher...
  11. P

    Schrodinger equation reduction using substitution

    SOLVED: Schrodinger equation reduction using substitution Homework Statement Given \frac{d^2 \psi}{dx^2} - Ax\psi + B\psi = 0 make a substitution using w= A^{1/3} (x - \frac{B}{A}) to get \frac{d^2 \psi}{dw^2} - w\psi = 0 Homework Equations The Attempt at a Solution...
  12. M

    Finding Pivots in Row Reduction: Does a Zero on Top Matter?

    Homework Statement When row reducing and trying to find the pivots, does it matter if there is a zero on top? i.e.: 1 2 3 4 0 8 0 5 0 0 4 6 i know that the 1st and 2nd columns are pivots but is the 3rd column a pivot also?
  13. K

    Analog finter design for harmonics reduction

    Hi, I have build an 12VDC- 12VAC inverter using a square wave gate signal for my power MOSFETs. My output is perfect square wave and now i want to clear the harmonics except the fundamental. I am not sure how can i design the analog filter that can filter the harmonics except the...
  14. 5

    Guassian Elimination (Row reduction) of 3 simultaneous eqn.

    Homework Statement I have been given the 3 following simultaneous equations and the question is: "(a) Solve the equations using Gaussian elimination, showing all your working." fairly simple topic i know, but i can't get the answer :/ The Attempt at a Solution Had a few attempts...
  15. B

    Reduction of Order Method - Differential Equation Help

    1. Problem Statement Okay so I know these appear to be simple but for some reason I am having trouble finding the methods by which to solve them. Problem 1: This problem must be solved by reduction of order method and cannot use the y2 formula. (1 - x^2)y'' + 2xy' = 0; y1 = 1...
  16. N

    Really simple matrix reduction

    Homework Statement I don't know why I keep getting this wrong...some help would be greatly appreciated. A = [ 0 -6 ] [-2 -3 ] (1) Write A as a product of 4 elementary matrices: Wouldn't that just mean to Reduce Row echelon it, and show it in 4 steps? (2) Write A^-1 as a...
  17. T

    Row Reduction Question: Independent w1 or w2? Answer Revealed!

    which one of w1 or w2 linear independent of the v groupr?? i got to the situation that each one of them could be independant and the other not ?? the answer in the book is that w2 is independent and the other is not v_1=\begin{bmatrix} 1\\ 1\\ -2\\ 1 \end{bmatrix}...
  18. mheslep

    Sunlight reduction in large volcanic events

    Last night I watched the fun, if not reliable, history channel piece on volcanic eruptions large enough to significantly reduce sunlight. I'm curious. What's a rough order of magnitude of sunlight reduction expected from the various size of events? Some quick googling gives me: Small...
  19. A

    Thanks.Boolean Algebra Reduction - Is There an Algorithm for It?

    Hi Everybody, I have a general question: Is there any Algorithm that can do Boolean Algebric Reduction ? Appreciate your help
  20. B

    Torque to speed reduction ratio

    hi,I was wondering if anybody would know the following: If I have a 200hp motor that has 600ft/lbs of torque at 1750 rpm and reduce the speed to 190 rpm with pulleys 9.2:1 does that give me 600ft/lbs x 9.2 = 5520 ft/lbs torque @ 190 rpms? thanks
  21. J

    Reduction of PDE to an ODE by means of linear change of variables

    Homework Statement So it's been a really long time since I've done any ode/linear algebra and would like some help with this problem. Derive the general solution of the given equation by using an appropriate change of variables 2\deltau/\deltat + 3\deltau/\deltax = 0 The thing that...
  22. L

    [Electrochemisry] How to find the Cathode and Anode, and oxidation and reduction

    Homework Statement This is from a lab question, but i think i did it right, i would just like some confirmation. I had to make an electochmical cell for a lab, (actually mutiple ones) but it asks me to find the anode, cathode, and which chemical underwent oxidation and reduction. If you have...
  23. T

    Reduce QED to QM: A Restatement Based on Creation/Annihilation Operators

    I've been spending some time to think about a really conceptually and mathematically clean way of showing how QED reduces to ordinary QM in low energy limit. More specifically, I would like to consider a restatement of multi-particle QM (of electrons) based on creation and annihilation...
  24. C

    Number of gear teeth in two-stage reduction gears

    In a two stage reduction gearbox is it possible to have more teeth on the gear pair (helical-parallel axis) of the 2nd stage? I ran through a specification for gear sizes and I am wondering if this is ok.
  25. R

    Help to prove a reduction formula?

    Homework Statement Let In = \int^{1}_{-1} (1-x^{2})^{n} dx. Use integration by parts to show that In = (\frac{2n}{2n+1}) In-1 for n \geq1. (The integral above is supposed to be between the limits -1 and 1... sorry I couldn't figure out how to make the limits appear...
  26. J

    Bridging Step of Krebs Cycle oxidatiion or reduction?

    Bridging Step of Krebs Cycle...oxidatiion or reduction? I am told that the following reaction is a oxidative decarboxylation: pyruvate +CoA + NAD+ ---> acetyl CoA + CO2 + NADH but NAD+ is reduced to form NADH... Do we call it an oxidation because we are interested in what...
  27. R

    Reduction of order differential eq'n

    Homework Statement Solve : y''+(2/x)y'+y=0 given that y=sinx/x is a solution Homework Equations The Attempt at a Solution y=vsinx/x is the other solution I worked out y'=\frac{vxcosx-vsinx+v'xsinx}{x^3} to work out y'' got extremely confusing for me,so I used an online...
  28. S

    Matrix word and elementary row reduction rules

    Homework Statement a house plan has 3 different floor plans: Plan A- 3 three-bedroom units, 7 two-bedroom units, and 8 one-bedroom units Plan B- 4 three- bedroom units, 4 two-bedroom units, and 8 one-bedroom units Plan C- 5 three-bedroom units, 3 two-bedroom units, and 9 one bedroom units...
  29. R

    Find Condition for Unique Solution to Row Reduction Homework Problem

    Homework Statement Find the condition of k such that the set of equations x+y-z=1, x+2y+kz=-1, x+ky-z=1, has a unique soltuion,infinite sol'n or no solution. Homework Equations The Attempt at a Solution In the augemented matrix form [1 1 -1 1] [1 2 k -1] [1 k -1 -1]...
  30. J

    Reduction formula, integration problem

    Homework Statement Part of an example of using reduction formula, I won't post the whole question as I get most of it, just at the very end, magical things happen with the working and things disappear, as they usually do with integration: The definite integral goes from 0 to pi/4...
  31. E

    2nd order differential equation using reduction of order

    Homework Statement Use the method of reduction of order to find a second solution of the given differential equation t2y'' - 4ty' + 6y, t>0; y1(t) = t2 The Attempt at a Solution Here's what I have so far: y = vt2 y' = 2tv + t2v' y'' = 2v + 4tv' + t2v'' so t2 (2v + 4tv'...
  32. I

    Further noise reduction techniques ontop of Savitzky-Golay FIR filter

    Hi PF Designers, Wasn't too sure if this would belong in the Electrical engineering forum but here goes. I'm designing a prototype for my thesis that will read in sensory data wirelessly to a MATLAB script. This sensory data is riddled with noise, however important data is contained in...
  33. K

    Oxidation or Reduction: NO3- to NO

    Homework Statement Is this oxidation or reduction: (NO3)- ---> NO (this is a half reaction I took from the full equation) Homework Equations Not necessary The Attempt at a Solution At first, I got the oxidation states of each of the atoms For (NO3)- N has an oxidation...
  34. K

    Diff EQ reduction of Order problem

    Homework Statement One solution y1(t) of the differential equation is given a) Use the method of reductions of order to obtain a second solution y2(t) b) Compute the wronskian formed by y1(t) and y2(t) Homework Equations (t + 1)^2y'' - 4(t+1)y' + 6y = 0 y1(t) = (t+1)^2 The...
  35. B

    Reducing Order: Is it Valid to Say G(x) = 0?

    I'm making an assumption while trying to solve DEs by reduction of order. I've got a short form equation that I can use to reduce it if and only if I can place the DE into standard form. The standard form with generic notation would be y"+ P(x)y' +G(x)y = 0 where P(x) and G(x) are continuous and...
  36. F

    Rainbow table reduction function

    I recently did some personal research into the aforementioned functions. I created a few simple functions based in part on sine (and cosine). Anyway, the basic idea was to get a seed from the sine of some number, since -1 =< sin N =< 1. However, I think that sine is not an ideal function to...
  37. E

    Dimentional reduction: branworld or Yau-calibi manifolds?

    string theorists, there are two approaches to reducing 11 dimensions to 4, they are large and we are stuck on one, or they are compactified, too small to see. Which approach makes the most contact with physics? Is it possible to have 1-2 large dimensions and a 4-folded Yau-Calbi space...
  38. H

    Reduction of velocity in an isentropic process?

    Hi all. We are to compare the effect of a shock wave, that is the irreversibilities associated. We have comptued that the upstream and downstream velocities of a shock wave are 1029 m/s and 266.8 m/s respectively. The upstream pressure and temperature is 105kPa and 290K. What question...
  39. H

    Shock waev? Isentropic reduction of velocity?

    Hi all. We are to compare the effect of a shock wave, that is the irreversibilities associated. We have comptued that the upstream and downstream velocities of a shock wave are 1029 m/s and 266.8 m/s respectively. The upstream pressure and temperature is 105kPa and 290K. What question...
  40. J

    Using reduction of order for Non-Homogenous DE

    I need help solving a higher order differential equation by reduction of order. It will be greatly appreciated if all steps are posted as well! y(Double Prime)-3y(Prime)+2y=5e^3x where y sub one =e^x. Ive tried to get the answer but end up with 3 constants.
  41. S

    How can the reduction formula be used to find the integral of tan^4 x?

    Homework Statement a)Prove the reduction formula: \int\ tan^n\ x\ dx\ =\ \frac{1}{n-1}tan^{n-1}\ x\ -\int\ tan^{n-2}\ x\ dx Hint: first write tan^n x as tan^{n-2} \ x\ tan^2\ x and the rewrite using tan^2\ x+1=sec^2\ x. b) Use the formula twice to find \int\ tan^4\ dx The Attempt...
  42. Peeter

    Reduction of a blade pseudovector quotient?

    For two blades: A \in {\bigwedge}^r B \in {\bigwedge}^{k-r} and a corresponding pseudovector for the wedge product of the two: I \in {\bigwedge}^k intuition tells me that the following scalar quotient: \frac{A \wedge B}{I} can be reduced to A \cdot...
  43. L

    How Much Sodium Borohydride Solution Is Needed for Compound B Reduction?

    please help fast! NaBH4 reduction... Homework Statement Compound B [structure shown below] was reduced with sodium borohydride. The student used 1.1015g of Compound B. She prepared the sodium borohydride solution by dissolving 1.0085g of sodium borohydride in sufficient solvent to...
  44. E

    Half-cell / reduction potential?

    Could anyone give me some pointers regarding this problem? Half-cell Xn+/X is connected with half-cell Yn+/Y and the potential difference is found to be 0.12V with Y being the positive electrode. Yn+/Y is connected with Cu2+ and the potential difference is found to be 0.13V with Cu being the...
  45. S

    Reduction Formula and Integration by Parts

    I was sick and missed class:uhh: ∫ sin^2x dx = x/2 – sin2x/4 + C (I see that there is a trig identity in the answer as sin2x = 2sinxcosx) What I tried (copying the example in the book) u = sinx du = sinxcosx dx (why is du not cosx?) v = -cos x dv = sinx dx (why is this not...
  46. S

    Plasma Drag Reduction & Hypersonic Travel

    I'd heard this was a relatively newer discovery -- that a blunt-body object traveling through a gas experiences a reduction in drag if that same gas is turned into plasma. I'm haven't read exactly why this occurs, but I'd presume that a gaseous fluid medium becomes easier to pass through if...
  47. Saladsamurai

    Another reduction to Wrench

    This one is really discouraging me. It looks sooooo easy since the forces are each in one direction The way I have usually handled these as a procedure is: Find F_r and then find M_r about some point and then decompose M_r into components that run parellel and perpendicular to F_r. Then I...
  48. Saladsamurai

    How Do You Convert Forces into a Wrench in Vector Mechanics?

    [SOLVED] Reduction to a Wrench So far I have moved the forces to point O where \sum F=F_r=-10.0\hat{j} I have also re-written each force in Cartesian-vector form where F_1=10[\frac{6i-6j}{\sqrt{72}}=7.071i-7.071j F_2=-10j and F_3=-F_1=-7.071i+7.071j. I am told to decompose each...
  49. Saladsamurai

    Reduction of resultant Moment/Force

    [SOLVED] Reduction of resultant Moment/Force So I have calculated the resultant force correctly but my solution for distance is incorrect. I keep getting 6.08 ft but the correct solution is 6.57 feet from B. I found F_r=798.499 which is correct. Then I used, \sum...
  50. W

    Is there a connection between row reduction and linear maps?

    Hi, everyone: I was wondering about the relation of a matrix , seen as a linear map, and its row-reduced form, seen the same way. More specifically: take a matrix M , seen as a linear map L. What is the relation between this map L given by M, and the linear map L' given by...
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