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. A

    Hurricane reduction through ocean surface cooling

    Old article: http://edition.cnn.com/2009/TECH/science/08/28/hurricanes.gates.gray/ What do you guys think? Where do you see this project going? The official word is that it's not being publicly funded. But if there was even a 10% chance it would work, I see governments lining up at the...
  2. A

    LSZ reduction formula derivation following Peskin's book.

    Question: In page number 225 of Introduction to quantum field theory of peskin and schroeder, looking at the equation that follows to Eq. (7.41), I cannot understand how the general state $|\lambda_K>$ (one eigenstate of the full Hamiltonian Lorentz shifted so its momentum be K) is annihilated...
  3. Stephanus

    Percentage of hydrocarbons in living organism

    Dear PF Forum, I'm interested in how much energy our organic waste contain. I have read this article https://en.wikipedia.org/wiki/Composition_of_the_human_body Elements composition of plants The elements composition of human body (and animal?) and plants resemble. Bacteria has slightly...
  4. T

    2 ways to calculate net standard reduction potential

    On chemwiki, they gave 2 equations to find the standard reduction potential of a cell: Eocell = Eocathode + Eoanode Eocell = Eocathode - Eoanode Why are there 2 equations and when do you use each one? Thanks
  5. B

    Simplifying a fraction (block reduction, control)

    Homework Statement 2*3*4*5/4+3*4*4*6 Homework Equations 2*3*4*5/4+3*4*4*6 The Attempt at a Solution 2*3*5/1+3*4*6 Knowledge gap 1 - I do not understand why if top and bottom are divided through by 4 there should be a 4 left in the denominator and why the rest of the numerators and...
  6. Dema

    Equivalence of formulas for time reduction factors in GR

    Hello, I’d have a question regarding two apparently different formulas for the time reduction factors for observers in orbit around a rotating black hole, as reported in this nice thread: Equation for time dilation of body in orbit around Kerr black hole? The first one is: $$A=\sqrt{g_{tt} +...
  7. M

    Block Diagram Reduction - Control Systems Engineering

    Homework Statement Determine the closed loop transfer functions of the systems shown below: Homework Equations Standard block diagram algebra. The Attempt at a Solution I've moved the take off point such that the diagram now looks like: I am having difficulty determining G1(s). The...
  8. G

    Reduction of endomorphisms

    Hello, I am studying reduction of endomorphisms and I came across a theorem that I can't understand completely. It states that: Theorem: Let ##E## be a finite dimensional ##K## vector space, ##K## sub-field of ##\mathbb{C}##, and ##f## be an endomorphism of ##E##. Then, ##f## is diagonalizable...
  9. Martin V.

    Understanding the Role of Matrix Multiplication in Solving Equations

    Hello hope you can help me. Can anybody tell me what goes on from equation 3 to 4. especially how gets in?
  10. B

    Rotational force of motor + potential gear reduction

    I'm trying to determine how powerful of a stepper motor I need for a project. I am attempting to take a display that weighs 15lbs and transition it from laying flat to inclined (approximately 45 degrees) using a stepper motor. I had considered a linear actuator since it would have been an easier...
  11. O

    Using a hot gas to drive a piston: entropy reduction?

    Suppose we have an insulated cylindrical container with a piston inserted from one end. Suppose the volume confined by the piston is full of a hot gas. Now let the gas drive the piston so that the volume is increased. Did the entropy of the system decrease because some of the energy of the...
  12. chad kimsey

    Strong reduction of organic acid group

    I've been thumbing back through my organic synthesis book to try and remember how to reduce a carboxylic functional group. I know how to do partial reduction to primary alcohols, or create aldehydes and or acyl halides. But isn't there a way to completely reduce it all the way to a hydrocarbon...
  13. E

    Compression due to temperature rise vs volume reduction

    If I have 2 sealed tanks A and B of 1 cu ft volume that contain air at atmospheric pressure and are at 300 deg K. temp absolute. For tank A I raise the temperature from 300K to 600K and I suppose the pressure will double due to this and would be 14.7 * 2 = 29.4psi absolute For tank B I use a...
  14. P

    Solve Reduction Problem for (1+x)^1/3 in Mathcad

    I have a function : (1+x)^1/3 and I need to do reduction in mathcad. I wrote this : But the problem is that : it does not work with negative numbers. How to fix it?
  15. D

    MHB Reduction of linear or non linear equation to first order.problem

    2xy'=3y' first how do i find it's solution
  16. A

    Reduction of 2nd order PDE to a first order equations system

    I want to convert this linear second order general form PDE to two equations: ##ϕ_{xx}+bϕ_{xy}+cϕ_{yy}+dϕ_x+eϕ_y+fϕ=g(x,y)## Converted equations: ##a_1 u_x+b_1 u_y+c_1 v_x+d_1 v_y=f_1## ##a_2 u_x+b_2 u_y+c_2 v_x+d_2 v_y=f_2## I want to find parametric values of ##a_1 ...f_2## How can I do...
  17. E

    Reduction or area deformation meaning?

    Hey there! While reading my mechanical design book, I had hard time to understand a particular paragraph if anyone could help. Attached to this post are two figures. 2-6 a and b. The first one is pretty simple to understand; the engineering normal stress strain curve...
  18. V

    Solving Force Reduction in Sheet Metal Shearing

    1.How to find the force required in shearing sheet metal out by a cutter that does not cut at ninety degrees, but the end is inclined slightly at 90 + x degrees? The usual form is shearing stress× plate thickness× cutting length. In the new case, the tool impinges progressively from a single...
  19. M

    MHB Is this a correct application of the reduction method?

    Hey! :o Is the following formulation of the reduction correct? Undecidability of an (positive) existential theory $T$ is proved often by reduction, i.e., by interpreting another (positive) existential theory $T'$, known to be undecidable, in $T$. Each formula $\phi'$ of the language of $T'$...
  20. sheenamd1

    Waterborne Paint Viscosity Reduction Equation?

    Hello! I am not sure if this is the right forum to post this in, but I am trying to come up with an equation to predict the viscosity of a waterborne paint after it has been reduced 10% with DI water. The following viscosities were measured at 20*C on a Ford #4 cup, units are in seconds. The...
  21. PhiowPhi

    Effects of Magnetic field span reduction?

    Given the following diagram: The conductor(C) of known volume(##V##) and resistance(##R##), passes a uniform magnetic field(##B##)at a constant velocity(##v##), via the following formula: ## \epsilon = -vBL## the induced EMF can be calculated. This conductor acts as a power source to a certain...
  22. M

    MHB Algorithm to answer existential questions - Reduction

    Hey! :o Lemma 1. For any $x$ in the ring $F[t,t^{-1}]$ ($F[t,t^{-1}]$: the polynomials in $t$ and $t^{-1}$ with coefficients in the field $F$), $x$ is a power of $t$ if and only if $x$ divides $1$ and $t-1$ divides $x-1$ (the divisibilities are meant, of course, in $F[t, t^{-1}]$). Lemma 2...
  23. G

    Mathematica Kaluza-Klein Reduction Via Mathematica

    Does any know how to perform Kaluza-Klein reduction via mathematica? The task becomes very tedious if the job is done manually when successive reductions are done.
  24. K

    MHB Dimensional reduction of system of ODEs

    Given a nonlinear system of eight autonomous differential equations with all variables and parameters living in the positive octant of real numbers: $$dX_1/dt = \ldots\\ dX_2/dt = \ldots \\ \ldots \\ dX_8/dt = \ldots$$ and given that $\lim\limits_{t \to \infty} K(t) \to 0$ for $K(t) = X_3(t)...
  25. Destroxia

    Troubleshooting Reduction of Order Equations: Where Did I Go Wrong?

    Homework Statement t^2*y^'' -t(t+2)y^' + (t+2)y=0 , t>0; ysub1(t) = t Homework Equations Reduction of order: A second solution is assumed to be of the form: ysub2(t) = v(t)*ysub1(t) The Attempt at a Solution So, the algebra in the first part of the process seemed to be correct...
  26. C

    Deflection in a Cantilever beam

    Hello, i was looking for ways i can reduce the deflection in the cantilever beam whose one end is fixed and load is applied at the free end. Few i thought of was, 1- Reducing the length of the beam 2- Increasing the modulus of elasticity of the beam 3- ?? 4- ?? 5...... Appreciate your help...
  27. N

    How do I calculate the cell potential?

    < Mentor Note -- thread moved to HH from the technical chemistryforum, so no HH Template is shown > I was given this problem: A voltaic sell uses the reaction 4Fe3+ + H2 --> 2Fe2+ +2H+. Find the cell potential when [Fe3+]=1.50 M, PH2=.50 atm, and [Fe2+]=.00100 M and the pH of both anode and...
  28. J

    How do I reduce the outer loop in the first question with 3 inputs?

    Homework Statement I have got 2 questions like this and I'm struggling any help would be much appreciated please. Thanks Homework EquationsThe Attempt at a Solution
  29. Safinaz

    Can Two Levi-Civita Symbols be Reduced to One with Indices?

    Hi there, Can two Levi-Civia symbols ## \epsilon^{ckl} \epsilon_{ibj} ## reduced to one with indices ## \epsilon_{kij} ## ? WHERE b and c run from 4 to 5, the other indices run from 1 to 3 and both symbols are multiplied by the following matrices: ## A_{ib}^c ~ B^{kl} ~ C_j ~\epsilon^{ckl}...
  30. aditya ver.2.0

    Dirac theory over gravitational constant reduction.

    Dirac had proposed that Gravitational constant would reduce with time.Why?
  31. M

    Simple Symplectic Reduction Example

    Homework Statement I'm struggling to perform a symplectic reduction and don't really understand the process in general. I have a fairly solid understanding of differential equations but am just starting to explore differential geometry. Hopefully somebody will be able to walk me through this...
  32. Elvis 123456789

    Is 3FeCl2 to 2FeCl3 and Fe(s) a Disproportionation Redox Reaction?

    Homework Statement Determine the oxidizing agent, reducing agent, element oxidized, element reduced, # of electrons lost per atom, and # of electrons gained per atom. State if the reaction is not redox. 3FeCl2(aq) ------> 2FeCl3(aq) + Fe(s) Homework EquationsThe Attempt at a Solution...
  33. Teemo

    Standard Reduction Potential Changes in Regards to Acidity

    Homework Statement The reduction of O2 to H2O in acidic solution has a standard reduction potential of +1.23 V. What is the effect on the half-cell potential at 25 °C when the pH of the solution is increased by one unit? O2(g) + 4H+(aq) + 4e- –> 2 H2O(l) (A) The half-cell potential...
  34. evinda

    MHB Is the Subgraph Isomorphism problem NP-complete?

    Hello! (Wave)Subgraph isomorphism We have the graphs $G_1=(V_1,E_1), G_2=(V_2,E_2)$. Question: Is the graph $G_1$ isomorphic to a subgraph of $G_2$ ? (i.e. is there a subset of vertices of $G_2, V \subseteq V_2$ and subset of the edges of $G_2, E \subseteq E_2$ such that $|V|=|V_1|$ and...
  35. P

    Testing the reduction of input to output ripple of MC7805

    Homework Statement How does the RC-link help with adding ripple to the signal? What would happen if the capacitor was removed (short-circuited)? Homework EquationsThe Attempt at a Solution I believe that the role of the capacitor is to pass on the AC voltage. Initially the capacitor is charged...
  36. G

    Control Systems Engineering - Block Reduction Help

    Homework Statement Hello, I'm trying to reduce the following block diagram Homework EquationsThe Attempt at a Solution I appear to be having some issues in doing this. The first thing that I did to reduce this block diagram was to take the forward path that has 2/(s+4) with negative...
  37. P

    Proof of reduction of order

    Homework Statement The method of reduction can be used to solve non-homogeneous equations with non-constant coefficients given by y''+py'+qy=g If Y1 is a known solution to the corresponding homogeneous differential equation, let y = vY1, w = v' Show that if w satisfies the linear first-order...
  38. Calpalned

    Reduction in the time range of a species

    6) REDUCTION OF DURATION? Why are the durations of species of hominids decreasing over time? The more modern the hominid, the shorter its existence. For example, according to wikipedia, Homo erectus lived from 1,900,000 BC to 70,000 BC. By comparison, the more recent neaderthals lived...
  39. AdityaDev

    Does the basicity of hydrides increase with larger atom size?

    I am confused with the statement given by a website (http://www.chem.ucalgary.ca/courses/351/Carey5th/useful/acidbase.html "Size. When comparing atoms within the same group of the periodic table, the larger the atom the weaker the H-X bond and the lower the electron density making it a weaker...
  40. Oxymoron

    Metrics and Group Structure Reduction

    I don't understand the geometry of what happens when you give a manifold a metric, in particular how the group structure reduces to the orthogonal group. I've read the wikipedia article http://en.wikipedia.org/wiki/Reduction_of_the_structure_group a dozen times but I get stuck when it says that...
  41. M

    Roger Penrose: Objective Reduction & Nonlocal Collapse

    Roger Penrose suggested that wf collapse is an objective phenomenon caused by gravity. Is there any actual model for this? For instance, how would the nonlocal collapse work with relativity?
  42. Hawk

    Methodology for weight reduction

    Hi all, as you know, aircrafts are highy dependant on their weight goals to be met or exceeded to ensure the performance perceived during the design studies can be realized. However, it is nonetheless often that the resulting design still becomes overweight in some way or place because you...
  43. PWiz

    Reduction of NADP in cyclic photophosphorylation

    I understand that an electron jumps to an excited state after absorbing a photon with the right energy (frequency) in photosystem 1 and exits the structure of the primary pigment, moves through different electron acceptors and returns to photosystem 1 (now at a lower energy state). What I don't...
  44. AdityaDev

    Reduction of quaternary ammonium salt

    I am confused with the reduction of quaternary ammonium salt. ##Ph-CH_2-CH_2-N^+Me_3## on reduction with Zn-Hg in HCl will not work. The -NMe3 is not disturbed(given in my text). But why? Also the text says On reduction with LiAlH4 or NaBH4, -NMe3 would be disturbed. what would be the product...
  45. R

    Control systems block diagram reduction

    Homework Statement Hi I am having trouble simplifying the attached diagram with respect to the return summing blockHomework EquationsThe Attempt at a Solution there shouldn't be any superposition since there is only one input signal, in the attached file I've simplified A to Be: G3/(G2-G2G3G4)...
  46. B

    Reduction of moisture content form propylene glycol

    Is it possible to reduce moisture content in Polyethylene glycol or propylene glycol by applying vacuum to around 15000 mTorr for 24 hours. If anyone has any idea please let me know
  47. ryanuser

    Can Gamma Ray Energy Be Reduced to Visible Light Through Material Interaction?

    Hi, my question is that would it be possible to reduce the energy and frequency of gamma rays to visible light then maintain it at that level?
  48. QuantumCurt

    Reduce Order | Find Second Solution for $$y''+4y=0$$

    Homework Statement Given - $$y_1(x)=sin(2x)$$, find a second linearly independent solution to $$y''+4y=0$$Homework Equations I'm using reduction of order to write a second solution as a multiple of the first solution. I think I've gotten to the right answer, my main question is in how I...
  49. C

    Validity of the Pauling Scale of Electronegativity?

    I propose the Pauling Scale is not valid in all circumstances, and other scales of electronegativity would do better to predict the behavior of electron density in molecules: Electronegativity seems to be poorly defined for such a widely used chemical property: a 'tendency' of an atom or...
  50. _N3WTON_

    D'Alembert's Reduction of Order Method

    Homework Statement Use the reduction of order metho to find a second linearly independent solution. What is the general solution of the differential equation? y'' - y = 0 y_1(x) = e^x Homework Equations Reduction of order formula The Attempt at a Solution First, I set: y = ve^x y' =...
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