What is Channel: Definition and 186 Discussions

Channel 4 is a British free-to-air public-service television network with a remit to produce "high quality and distinctive programming". Its headquarters are in London, with a national headquarters in Leeds and creative hubs in Glasgow and Bristol.The channel was established to provide a fourth television service to the United Kingdom in addition to the licence-funded BBC One and BBC Two, and the single commercial broadcasting network ITV.
It began transmission on 2 November 1982, the day after Welsh language broadcaster S4C's launch. Although largely commercially self-funded, it is ultimately publicly owned; originally a subsidiary of the Independent Broadcasting Authority (IBA), the station is now owned and operated by Channel Four Television Corporation, a public corporation of the Department for Digital, Culture, Media and Sport, which was established in 1990 and came into operation in 1993. In 2010, Channel 4 extended service into Wales and became a UK-wide television channel.

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  1. P

    B Alternative Interpretation of Bell Test: 40 Nanoseconds & Photon Perspective

    When interpreting the results of the two channel Bell test, I believe there were roughly 40 nanoseconds between when the particles were created and when they hit the polarized lens. It is believed that sometime during this time information passes between the entangled photons so that they match...
  2. P

    Fluid flow acceleration in a channel

    MODERATOR NOTE: THIS HOMEWORK WAS SUBMITTED TO A NON-HOMEWORK FORUM SO THERE IS NO TEMPLATE Hi everyone, I'm stuck on a fluid mechanics problem and maybe you could help me. As shown in figure, there is a two-dimensional converging channel, in which cross-section area varies linearly with x...
  3. S

    What is the flow through pipe in an open channel?

    I know this is easy but i need to know the flow velocity through a pipe reducing in diameter inside a canal. the water velocity is 3m/s water depth is 1.5 m the pipe is at the bottom inlet diameter 0.9m small reduced diameter 0.6m outlet diameter = 0.8m note: this is an open canal with...
  4. Syed Alam

    Enthelpy rise hot channel factor and Radial form factor

    I am currently designing a whole-core for small PWR. I am calculating core life (years) vs. FdH and RFF. What is the difference between "Enthalpy rise hot channel factor (FdH)" and "Radial form factor (RFF)"? I have calculated "CHANNEL FDH" which is same as "RFF". Do I have to try "CHANNEL...
  5. L

    Convective heat transfer coefficient in channel

    Hi, I need to measure heat transfer coefficient in the block channel. However, the block is not general block. Inside block, there is trapezoid object. So, water flow rate in the first is low speed because big square. Then the square size will decrease then the speed is high. Do you know how...
  6. M

    Science/academic radio channel ?

    Hello, I was wondering if there exists a decent radio channel which main focus would be science/technology and academia ? I'm listening radio pretty much all the time while working, all I could find were "sensational" tech talk show about UFOs, zombies and time travel, nothing serious. The...
  7. Syed Alam

    Hot Channel Analysis of Small PWR core

    I am currently working on thermal-hydraulics of a small PWR. The configurations are: Thermal power (MWth) 333 Core height is 1.8 m Pressure (MPa) 15.5 Total rod diameter (mm) 9.50 pin pitch (mm) 12.65 Pitch/diameter ratio 1.33 Flow Area (m2) 8.92E-05 Intlet mass flow/area (kg/m2/s)...
  8. T

    Pressure and velocity calculation for microchannel. pls help

    Me and my friends have been trying (b) for soooo long! we have gone to PhD students and some fluid dynamic doctors for held and they cannot figure this out. 1. Homework Statement 2) This question concerns the design of a ‘micro-chemostat’ device. E. coli exhibiting chemotaxis can swim up to...
  9. A

    Static Pressure along bounded channel

    Homework Statement [/B] Note: There is NO z variation, everything is horizontal (imagine looking down at streamlines)Homework Equations Bernoulli's Equation along streamline: P + 1/2*ρ*V2 + ρ*g*h = Constant ... (1) Bernoulli's Equation normal to streamline: P + ρ*V2*(1/R) + ρ*g*h =...
  10. terryds

    Best physics video channel for Olympiad students?

    Hi.. I take a high school physics Olympiad. Could you please tell me what the best physics video channel on YouTube or other sites ? I'm looking for videos that gives an overview to an advanced problem (It can be IPhO level) and guide to the solution step by step..
  11. TheDemx27

    Golang Concurrency: Ignoring request from channel

    I'm going back to basics again in an attempt to add golang to my list of "pretty well learned" languages. What I need to do should have a pretty simple solution: I want to ignore a request to get a result from a channel in golang, if you need to know the particular situation I have a link to my...
  12. B

    Is There a Simple Way to Route 9 Channels with Multiple Connectors on a PCB?

    Hi, I am designing a PCB with multiple 2-pos DF13 connectors in it (Like 50+). at the end of the board there is a 10 pos. cable. My intent is that the user (me) connects up to 9 channels in any position I like (I have 50 possible choices). However, this board is connected to another PCB that...
  13. D

    MOSFET Channel length modulation

    In Sedra&Smith's microelectronic circuits they have the following expression for the drain current in a MOSFET in saturation iD = 1/2µpCox(W/L)Vov2(1+VDS/VA)But I don't see how this can be correct. Wikipedia also has another expression, see...
  14. B

    Action Potential Through Ion Channel, Total Number of Ions Through

    Homework Statement Nerve signals in the body occur when a small voltage, called an action potential, is applied across the membrane of a cell. When this action potential is applied across a region of the cell membrane called an ion channel, current in the form of moving potassium ions will be...
  15. Undulator

    2D PIC simulation for untapered plasma channel

    Hello everyone, I would like to get ~200 MeV quasi-monoenergetic electron beam by doing 2D Particle-In-Cell simulation in bubble regime. The moving window dimension is 50x50 μm for x and y, the simulation mesh size is set 0.04x0.4 μm, each mesh includes 10 particles, laser wavelength is 800 nm...
  16. B

    Allowable Uniform load on steel channel

    I am attempting to determine the allowable uniform load on a 8ft long C3x5 steel channel A36 steel. i got an answer of about 2,455lbs but idk if that's right. if there is an easy equation to follow or if you know of a table online somewhere that can help that would be awesome! thanks in...
  17. jedishrfu

    History Channel Show on Star Trek and Physics

    Interesting Hist Channel show on Star Trek and Physics: https://www.youtube.com/watch?v=vNiDoT7blX8 Of particular interest is the number of scientists who were influenced by Star Trek in their youth.
  18. N

    Idea for a name for a physics youtube channel?

    So my friends and I want to start a youtube channel doing stuff with math and physics and such, but we can't come up with a clever name, any suggestions? Thanks!
  19. R

    L (Angle) & C (Channel) beam sections versus an I section

    In terms of unit material spent my impression is that an I beam uses it most efficiently at least for non-torsional loads? i.e. putting most material far from the axis into the flanges giving higher moments. If so, what are situations when an angle or channel cross sections are preferred in...
  20. B

    Two Channel Microphone: Right & Left Channels Explained

    if you have a two Channel Microphone, what does that mean ? do you have to separate the right and left channels before you send it to a FFT? if so why?
  21. I

    MHB New YouTube Channel for Stats Help

    Hello Everyone, As a long-time University Teaching Assistant in Statistics, I have recently launched a YouTube Channel with the idea of providing help for students who are taking courses in introductory statistics and probability. The videos it contains are the online equivalents of the Review...
  22. C

    What is Channel Number? (In gamma spectroscopy)

    Really quick question. In a graph like this: http://en.wikipedia.org/wiki/File:Cs137_Spectrum.PNG Source What does the Channel Number represent? Also, just to make sure, am I right in saying the count rate is \frac{\delta m}{\delta t} ? where m is the cumulative number of scintillations and...
  23. Z

    What's the physical interpretation of ρ for dipole forbidden channel?

    Consider we have a \Lambda type three level system, the one upper level is denoted by 3, and the two lower levels are denoted by 1 and 2. Assuming that the transitions between 1\leftrightarrow3 and 2\leftrightarrow3 are dipole alowed, while the transition between two lower states 1 and 2 is...
  24. S

    Onset of fully developed flow in a channel

    Suppose we have a case of laminar flow in a channel. For a case of constant flow rate, at some point downstream of the channel inlet, the hydrodynamic and thermal boundary layers will merge and simultaneously developing flow will transition to full-developed flow (not necessarily at the same...
  25. A

    YouTube channel Life on Enceladus

    Hi, I'm new. :biggrin: I'm currently studying A-levels, and I'm going to study astrophysics at uni, so I may be on this website quite often asking questions in the future! Secondly, I have a question. Why is there LIQUID water under Enceladus' surface? Is it similar to Europa around Jupiter...
  26. L

    Documentaries on Discovery Channel

    Hi everybody! I would like to ask you two things. Some months ago i watched some documentaries on Discovery Channel but i don't remember the title! I can only remember that they was talking about p-brame theory and that some physicists wasn't able to describe it! And in anther they were talking...
  27. D

    Laplace equation in rectengualar channel (Fluid mechanics)

    Homework Statement Estimate the speed a potential flow in gravity field would have in direction y in rectangle channel with depth h [/iteh] and length l . The fluid is incompressible and on the surface z = 0 we have boundary condition \dfrac{\partial^2 \phi}{t^2} + g\dfrac{\partial...
  28. R

    Measuring Voltage with an Oscilloscope: Channel A RMS Voltage

    1. An oscilloscope is used to measure the voltage across two components using Channel A and Channel B. Deduce the RMS voltage of the signal measured by Channel A I just want to know what they mean by "deduce the RMS voltage" Do i need to calculate the Vrms?
  29. U

    How can I find 4 channel oscilloscope in multisim 11

    Hi, how can I find 4 channel oscilloscope in multisim 11.0? or how can I add 4 channel oscilloscope to multisim?
  30. D

    Determine depth of a channel

    Homework Statement A rectangular channel has a width of 2 meters, and an slope of 1:80. The Manning's number for the entire channel is n = 0,014. In this situation the depth is y= 1,50m. The flow of water is normal. Further down the slope decreases to 1:150 and the width increases to b=3...
  31. iVenky

    Capacity of a discrete channel

    Well I was reading this " A Mathematical Theory of Communication" paper by Claude Shannon. He says that the capacity of a discrete channel is given by [ tex ] C= \ \lim_{T \to +\infty} \ \frac{\log ( N(T) )} {T} [ \tex ] Here N(T) is the number of possible sequences in a duration of T...
  32. S

    D/A Communications - Minimum bandwidth of a channel

    Homework Statement Homework Equations The given channel transfer function and PSDs. Note that the capital Pi symbol in the PSD of the message symbolizes the rectangle function so Sm(f) = 8rect(f/8000) The Attempt at a Solution From my understanding, channel noise is not filtered at this...
  33. B

    Help in a channel coding question

    Homework Statement Consider a particular channel coder that has a generator matrix G =[1 1 1 1 1] 1 -Generate all the allowable codewords for c . What do you think this code is called? 2- What is the minimum distance for this codeword? Describe how it might work to correct errors. Homework...
  34. M

    Theory of BiQuad Antenna Design (now a digital TV channel question)

    Hi everyone, I'm Designing a BiQuad antenna for WiFi applications. The design and optimization are relatively simple but i need some references of the theory behind this antenna. I'm reading some theory of Bi-Conic Antennas but it's a bit difficult to extrapolate the idea between both...
  35. S

    Open channel flow, mannings equation and specific energy

    Homework Statement A 4m wide channel has a bed slope of 1 in 1500 and a Manning's roughness coef n=0.01. A broad crested measuring weir in the form of a streamlined hump 0.4m high spans across the full width of the channel. the discharge is 10.5m^3/s. Determine i)the uniform depth of flow...
  36. P

    Single Channel Blind Source Seperation

    Homework Statement I am trying to figure out how to do independent component analysis on a single stream of time series data. The ica algorithm comes as part of the it++ package however it is necessary to perform some preprocessing on the time series data as ica works on the premise that the...
  37. Z

    Waveforms compatible with transmitting channel?

    why waveforms should be compatible with transmitting channel? What if i send a random wave without having much information about it?
  38. A

    Laminar air flow in a 2D channel - how to ensure that a flow is fully developed?

    Hello everyone, I am studying laminar airflow in a channel (2D) and trying to simulate it with FLUENT software but I need to know about the entrance length, and I want to know how I can be sure that a flow is fully developed? is it just by looking at the velocity profile? or looking at the...
  39. D

    How many potassium ions pass through if the ion channel opens for 1.0 {\rm ms}?

    Homework Statement The biochemistry that takes place inside cells depends on various elements, such as sodium, potassium, and calcium, that are dissolved in water as ions. These ions enter cells through narrow pores in the cell membrane known as ion channels. Each ion channel, which is formed...
  40. dexterdev

    Why do we consider zero mean for gaussian noise in a communication channel?

    Hi all, I got an idea why noise is having a gaussian pdf but didnot understood why it should be having zero mean. Why can't noise contain a dc content. -Devanand T
  41. T

    MOS Cascode Amp: Find the early voltage and channel length

    Problem: In a MOS cascade amplifier, the cascade transistor is required to raise the output resistance by a factor of 40. If the transistor is operated at VOV = 0.2 V, what must its VA be? If the process technology specifies V'A = 5 V/μm, what channel length must the transistor have? Given...
  42. E

    Top channel and electroweak breaking

    A paper I am reading says My question is, "What does this mean?" The paper deals with WIMP annihilations into a photon and a Higgs which I suspect occurs via a fermion loop. I seem to recall that such triangle diagrams yield amplitudes proportional to the mass of the fermion in the loop (which...
  43. T

    Water flow down a porous channel (Navier-Stokes/Fluid dynamics)

    Homework Statement Water flows down a channel whose floor is porous, so that water seeps out of the bottom of the channel at a speed v, where v is constant and much less than the flow speed, U, along the surface of the channel. The seepage rate is slow so that H may be regarded as constant...
  44. B

    National Geographic Channel Blows It Again

    I've just seen a program(me) on the National Geographic Channel entitled: "Confederate Flying Machine", which started out as an attempt to concept-test a design for a "Artis Avis" ("Artificial Bird", or aeroplane) by Confederate inventor R.O. Davidson, but soon became a concept test of the...
  45. M

    Fluid mechanics, open water channel velocity - bernoulli & conservation of flow

    Homework Statement If in an open water channel, the approach speed of an incompressible ideal fluid, of constant depth h1, is not too large, a small bump in height H (H<< h1) in the base of the channel will cause a dip Δh (Δh << H) in the water level directly above it, such that h1 = Δh + H...
  46. H

    Fluid Mechanics Open Channel Problem

    The problem: A canal cut in rock (n= 0.030) is a trapezoidal in section with a bottom width of 6.10m and the side slopes of 1 on 1. The allowable average velocity is 0.76 m/s. What slope will produce 5.66 m^3/s? The books answer is 0.000675 from the mannings equation V=(1.486/n)R^2/3 x...
  47. C

    U Channel Deflection and adding ribs for strength

    Hi everyone, I am trying to find out what the deflection would be for some steel U channel cold worked from sheet. U channel would be 2.250 in. (depth) x 1.0 in. (wide) x .040 (web thickness). Case (1) Supported at both ends. Length 50 in. Load 72 lbs. evenly distributed. Case (2) Same as...
  48. S

    Queueing Model where inflow has to wait for outflow because of a shared channel

    Hi I am look for a mathematical queuing model that can help with/solve the following scenario. I believe this scenario can me modeled in a dynamic simulation, but I am in need of a solution for a static model. Scenario: You are at a port. There is a steady, equally distributed arrival...
  49. R

    Is the Holevo Quantity Preserved under Channel Applications?

    I'm trying to prove that the Holevo quantity does not increase when a channel is applied to the ensemble of states. So, if \Phi(ε) = { (p(a), \Phi(ρa)) : a\in\Gamma}, then I want to prove that \chi(\Phi(ε)) ≤ \chi(ε) where \chi refers to the Holevo quantity. I'm trying an...
  50. S

    Investigating the effects of changing the length and width of transistor channel

    Hello, I posted this here because it is for a bit of course work, but I am just looking to confirm if I am using the right equation. I hope this is ok! If not, sorry! I just didn't think since I was asking a specific assignment question, I would post here. I need to investiage how changing...
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