Carrier Definition and 139 Threads

The escort carrier or escort aircraft carrier (U.S. hull classification symbol CVE), also called a "jeep carrier" or "baby flattop" in the United States Navy (USN) or "Woolworth Carrier" by the Royal Navy, was a small and slow type of aircraft carrier used by the Royal Navy, the United States Navy, the Imperial Japanese Navy and Imperial Japanese Army Air Force in World War II. They were typically half the length and a third the displacement of larger fleet carriers, slower, carried fewer planes, and more-lightly armed and armored. Escort carriers were most often built upon a commercial ship hull, so they were cheaper and could be built quickly. This was their principal advantage as they could be completed in greater numbers as a stop-gap when fleet carriers were scarce. However, the lack of protection made escort carriers particularly vulnerable, and several were sunk with great loss of life. The light carrier (U.S. hull classification symbol CVL) was a similar concept to the escort carrier in most respects, but was fast enough to operate alongside fleet carriers.
Escort carriers were too slow to keep up with the main forces consisting of fleet carriers, battleships, and cruisers. Instead, they were used to escort convoys, defending them from enemy threats such as submarines and planes. In the invasions of mainland Europe and Pacific islands, escort carriers provided air support to ground forces during amphibious operations. Escort carriers also served as backup aircraft transports for fleet carriers, and ferried aircraft of all military services to points of delivery.
In the Battle of the Atlantic, escort carriers were used to protect convoys against U-boats. Initially escort carriers accompanied the merchant ships and helped to fend off attacks from aircraft and submarines. As numbers increased later in the war, escort carriers also formed part of hunter-killer groups that sought out submarines instead of being attached to a particular convoy.
In the Pacific theater, CVEs provided air support of ground troops in the Battle of Leyte Gulf. They lacked the speed and weapons to counter enemy fleets, relying on the protection of a Fast Carrier Task Force. However, at the Battle off Samar, one U.S. task force of escort carriers and destroyers managed to successfully defend itself against a much larger Japanese force of battleships and cruisers. The Japanese met a furious defense of carrier aircraft, screening destroyers, and destroyer escorts.
Of the 151 aircraft carriers built in the U.S. during World War II, 122 were escort carriers, though no examples survive. The Casablanca class was the most numerous class of aircraft carrier, with 50 launched. Second was the Bogue class, with 45 launched.

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  1. K

    I Wavefunction of a free particle has carrier and envelope parts

    If ##\psi(x, t)=\left(\frac{1}{2 \pi \alpha^{2}}\right)^{1 / 4} \frac{1}{\sqrt{\gamma}} e^{i p_{0}\left(x-p_{0} t / 2 m\right) / \hbar} e^{-\left(x-p_{0} t / m\right)^{2} / 4 \alpha^{2} \gamma}##where * ##\gamma=1+\frac{i t} {\tau}##( a complex number) * ##\tau=\frac{m h}{2...
  2. A

    A The main charge carrier in the ionic crystal is polaron or conduction?

    Suppose I have a perfect crystal(e.g.TiO2-Rutile, band gap=3ev), under UV light, there should photoconductivity, according to the condensed matter theory, some of these excited conduction band electrons would form small polarons, I am wondering how many percent of the free conduction band...
  3. Lord Doppler

    Engineering Voltage Carrier Signal and Voltage Modulating Signal (AM)

    Hello everyone, I'm trying to find the Voltage Carrier Signal and Voltage Modulating Signal from the power spectrum of a AM signal 1) I change the scale dBW to W and I have this: From this I have that Pc (Power of the Carrier signal) is 50 W and I don't know how to continue with the...
  4. berkeman

    Is this an antenna array on the new Chinese aircraft carrier?

    I saw this photo at CNN.com today, and I'm trying to figure out what the function could be for what looks like a linear antenna array lining both sides of the aircraft ski-jump launching ramp. They look to be an array of about 10m verticals along each side of the bow, but with the base of some...
  5. M

    Frequency Shift Key Modulation: how are the carrier frequencies chosen

    Question: For frequency shift key modulation in the binary case, how are the two carrier frequencies chosen? From online reading, I have seen that the carriers are chosen to be different but also with the goal of minimising bandwidth and without any overlaps of the spectra, etc. However, I...
  6. halleff

    Diffusion current and carrier concentration equilibrium (unbiased)

    Suppose you have a non-uniformly doped piece of semiconductor (without an applied bias) such that the acceptor dopant concentration Na(x) decreases from left to right (as x increases). In this case, the equilibrium hole distribution p(x) will not be uniform since then there would be a net drift...
  7. K

    News Brett Crozier, Captain of aircraft carrier fired

    I was reading this news https://www.thedailybeast.com/navy-to-fire-captain-brett-crozier-of-virus-stricken-uss-theodore-roosevelt-who-begged-for-coronavirus-help As I'm far from good when it comes to understand english terms... what do they mean by fired? Does it mean just that he is no longer...
  8. R

    How Does Amplitude Modulation Work in Radio Transmission?

    Is the carrier wave modulated or in other words "modified" with the information signal? If so how exactly is this done? I can't find or maybe I am looking at the wrong things but I don't understand how this is done. I know that AM is modulated with the amplitude and FM is modulated by the...
  9. B

    How to calculate Carrier Concentration vs. Depth from a CV measurement?

    I'm trying to obtain the free carrier concentration vs depth profile from the CV (capacitance-voltage) measurements of a normally-on HEMT with the expressions used for a Schottky barrier, but I´'m confused about how to extract the values for depth. I found in textbooks and articles that the...
  10. Z

    A What Happens When Semiconductor Intrinsic Carrier Density Exceeds 10^15 cm^-3?

    Is there a rule of thumb that once a semiconductor's intrinsic carrier density reaches 10^15 cm^-3, that the semiconductor cannot effectively be used to perform useful operations?
  11. hagopbul

    About the heat carrier in a nuclear reactor

    Hello: I have small question , as I read about the ATF research in the news ,a question present it self , why no one does any research on heat carrier in nuclear reactor that can absorb nuclear radiation and change it to infra red radiation ? Best H
  12. Y

    What formula would i use this for this HW problem? (Aircraft carrier jet launch)

    *This is an introductory physics class for non-math majors. A typical jet fighter launched from an aircraft carrier reaches a take-off speed of 175mph over a distance of 310 ft. assuming the acceleration is constant, what is the jet's acceleration in (meters per second)? 2) how long does i...
  13. O

    Frequency of Modulated Signal: Carrier vs Message

    If a carrier signal is 1000 Hz, and my message signal has a bandwidth of 100 Hz. Is there any change in frequency of the modulated signal? Why is it said that the message signal is now operating between 1000hz +/- 100Hz? I thought the original message signal frequency remains unchanged...
  14. fluidistic

    I Charge carrier density: Hall experiment vs Fermi-Dirac statistics

    Many times, the charge carrier density of a material is determined from a Hall effect experiment, from ##R_H=1/(ne)## (SI units). Where ##R_H## is determined from a measured voltage and other controllable parameters. As far as I know, this simple formula comes from the obsolete Drude's model...
  15. B

    Calc Electron & Hole Concen in Silicon at 300K

    Homework Statement For silicon at T=300K with donor density ND=2×109cm−3, acceptor density NA=0 and ni=8.2×109cm−3, calculate the equilibrium electron and hole concentration Homework Equations n_0=\frac{N_D-N_A}{2}+\sqrt{\frac{N_D-N_A}{2}^2+n_i^2} p_o=\frac{n_i^2}{n_0} The Attempt at a...
  16. K

    B Carrier wave double slit experiment

    If you created the following double slit experiment would you still see interference? 1) Modify the slits so that the path from photon source through one of the slits to the detector is much shorter than the path through the other slit. 2) put a shutter in front of the photon source so that you...
  17. ADDA

    Carrier Signals and demodulation of audio waveforms

    Is the failure to remove the carrier frequencies the problem with the audio output in the following videos?
  18. Marcin H

    Semiconductors - Carrier Recombination

    Homework Statement A sample of Si at room temperature is doped with acceptors at a concentration of 3E16 cm^-3. An excess electron hole pair density of 1E14 cm^-3 is generated at some time t = 0. At t = 13.9 μs the excess EHP density is measured and found to be 5E13 cm^-3.(A). Does the initial...
  19. D

    Question - Mechanical (two-piece carrier)

    <<<Moved from another forum. No template. >>> I have to solve this mechanical Problem... I solved it, but I get fpór By=0,448F (see at my calculation!) and the right answer is 0,3F...what did I wrong? I should solve A B C! B is a two-piece carrier. F and a is given!
  20. N

    Carrier spacing related to period to go in phase

    Hi, I start at 100 MHz have 10 carrier frequencies all starting in phase at t=0 and the carrier frequencies have 25 kHz spacing. So my frequency range is 100-100.25 MHz, with 10 single frequencies equally spaced in this range. They are therefore all different frequencies, spaced 25khz apart...
  21. Kara386

    Intrinsic carrier concentration where did I go wrong?

    Homework Statement I've looked up the intrinsic carrier concentration of silicon, and what I've got isn't close. The question says given there are ##2\times 10^{22}## electrons per cubic cm in silicon, and the bandgap is ##1.1##eV, what is the free electron concentration at room temperature...
  22. Grands

    Physics What kind of jobs can a physicist do outside of academia and research?

    Hi guys. I want to make a question about what kind of job can a physicist do. Excluding the academic carrier and the research, which kind of job can a physicist do? It is true that there are physicist that work at Wall Street? If yes, what kind of job they do there? A technical job? I don't...
  23. I

    How to center the bandwidth for carrier frequency?

    I have a baseband signal in IQ form. I have a method to calculate the carrier offset and estimate the carrier bin. I want to center the carrier to the middle of the bandwidth. How do I do so? Do I simply multiply the IQ data by the exponential with the carrier offset, but doesn't that shift the...
  24. R

    Radio Carrier Signal Trouble Understanding

    I seem to have a lot of trouble understanding radio carrier signals I have read a bunch of stuff online and seen videos trying to explain it but I just can't understand it! Could some of you who understand try and give me some analogies or anything that might help me out? Thanks alot!
  25. Spinnor

    Stratolaunch carrier plane, active vibration reduction?

    Interesting new jet plane has rolled out of its hanger. https://img.purch.com/h/1400/aHR0cDovL3d3dy5zcGFjZS5jb20vaW1hZ2VzL2kvMDAwLzA2Ni80NjMvb3JpZ2luYWwvZHJvbmUxX3dlYnNpdGUuanBnPzE0OTYyNjgyNTY= It looks like there are vibration modes of the plane that during normal operation would shake the...
  26. I

    Intrinsic semiconductor, carrier concentration

    Homework Statement An intrinsic semiconductor with a direct gap have valance band ##\epsilon_k = E_v-b|k|^2## and conduction band ##\epsilon_k = =E_c+a|k|^2##, with ##E_v=6.0##eV, ##E_c = 5.5eV##, ##a=5.0eV\cdot Å^2##, and ##b=3.0eV\cdot Å^2##. Calculate the chemical potential ##\mu## and the...
  27. H

    I Does carrier pulse width vary with diffusion coefficient?

    Hello Physics Forums I’m doing some numerical studies on diffusion. I began with monte carlo simulations on gas diffusion, and more recently I’ve started to dabble in carrier diffusion inside semiconductors. It looks like diffusion in semiconductors is a lot more amenable to experimental study...
  28. Kara386

    Hall effect -- calculate carrier mobility and density

    Homework Statement A metallic film has length L=10mm, width W=1mm and thickness t=1##\mu m##. The current is parallel to the long edge and has magnitude ##I=0.7A##. Longitudinal voltage is ##V=1V## and it doesn't change with magnetic field. The Hall (transverse) voltage ##V_H## increases at...
  29. R

    Charge carrier drift velocity of wire

    Homework Statement Homework EquationsThe Attempt at a Solution Current is I = nqvA so drift velocity V is: V = I/nqA Drift velocity for x is: Vx = I/nqA Drift velocity for y is: Vy = 2I/nqA So the ratio of Vx : Vy should be 2:1 since Vy is equal to 2 lots of Vx?? (but correct answer is B)
  30. A

    Clarification "Force Carrier" and "Radiation" Gravity and EM

    I need clarification on the difference between a “force carrier” and “radiation.” Imagine two electric charges separated by a distance “d” but not moving. They exchange “force carrier” photons which tell the electric charges to attract/repel. But you can’t see these “force carrier” photons...
  31. D

    A Carrier concentration temperature dependence; semiconductors

    Hi all, I'm reviewing device physics and I would like to understand how majority and minority carrier concentrations for both N- and P-type substrates change with temperature. My reference, Pierret's Semiconductor Device Fundamentals, has this figure: and I want to generate curves for all...
  32. A

    A Minority carrier lifetime determination

    I would like to know if it is possible to measure minority carrier lifetime in 300um silicon detectors that have already been cut from the wafers that were fabricated using a set of photo-masks with layers including phosphorus and boron diffusion, metalization of both sides and passivation...
  33. M

    Amplitude modulation of signals with [suppressed] carrier

    Hello everybody, I'm a little bit confused about two types of amplitude modulation. We distinguish here: Case I : Amplitude Modulation with suppressed carrier (https://en.wikipedia.org/wiki/Double-sideband_suppressed-carrier_transmission): Case II : Amplitude modulation with carrier: Now...
  34. F

    I Carrier Concentration in a Semiconductor

    Suppose I have an n-doped semiconductor and want to measure the electron concentration in the conduction band as a function of temperature. How would I go about doing this by measuring the Hall coefficient as a function of temperature, given that I don't know the electron and hole mobilities...
  35. O

    Measuring minority carrier density and mobility

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  36. K

    Steady state excess carrier - Semiconductor

    Please check the following questions. Steady state of semiconductor w.r.t excess carrier. 1. If we shine photons on semiconductor and then turn the light off, semiconductor is not under the steady state condition. (it is under transient state since excess carrier concentration is decreasing)...
  37. onion3000

    Help with understanding modulation in AM, FM and PM radio

    I have a few questions about AM, FM and PM. 1. If FM (or PM) radio modifies the frequency of the signal, how is the signal picked up without having to change the frequency constantly? 2. If PM modulates phase, which modulates frequency, what is the difference between PM and FM? 3. Why is AM...
  38. O

    Carrier concentration in a semiconductor

    Homework Statement The question is in the picture attached. When Na=0, that means the acceptor concentration(i.e. open holes?) is zero? Homework Equations (Nd-Na)/2 + sqrt((Nd-Na/2)^2+ni^2) (Na-Nd)/2 + sqrt((Na-Nd/2)^2+ni^2) The Attempt at a Solution Solving for Nd=10^8: majority carrier =...
  39. A

    Tension in landing cable on an aircraft carrier

    Homework Statement [/B] Keep in mind this is a Top Gun-themed homework assignment. Cougar comes in for a shaky landing. His 20422 kg airplane traveling at 85 m/s strikes the deck at 3.5 degrees below the horizontal. Cougar's plane snags the landing cable stretched across the deck. The landing...
  40. M

    Derivation of Carrier Concentration (ni)

    < Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > I am following a lecture on carrier concentration and I got to the point where the instructor said that for homework, derive the carrier concentration equation ni, which...
  41. Dark_Capacitor

    Why AM wave is multiplication of carrier and message signal?

    Let A= (sin(x) * sin(100x)) + sin(100x).; modulation index is 1; Let B= (sin(x) + sin (100x)); Both of these waves have same frequency and both are amplitude modulated. When passed through an envelope detector, both will give message signal. And B have an advantage of not having any sideband...
  42. R

    Refractive Index change with Wavelength & Carrier Concentration

    I need to calculate the refractive index of a semiconductor material over a wavelength range (1×10-5m - 1×10-9m) and with different values of electron and hole carrier concentrations (i.e. n/p doped). I found this equation that relates those parameters: n+ik = √ [ (εm -...
  43. BiGyElLoWhAt

    Carrier particles and E-Field Propagation

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  44. B

    Is it possible that Higgs is a force carrier?

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  45. R

    Carrier flow in BJT when saturated

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  46. vead

    Boltzmann equation for carrier transport

    I am little bit confused about derivation for Boltzmann equation for electron look at this link http://relativity.livingreviews.org/Articles/lrr-2008-10/articlesu25.html which is final boltazmann equation ?
  47. S

    Maths of carrier densities in p-n junction w/ bias.

    Hi, I'm trying to recreate some formulae of my professor's but I'm hitting a dead end. Starting with the following equation for the electron carrier density in the conduction band of a semiconductor: n = N_c exp(\frac{-(E_c - E_f)}{kt}) N_c is just a constant, E_f is the electron...
  48. S

    Typical carrier frequency for amplitude modulation

    What is a typical carrier frequency for amplitude modulation? In particular, for amplitude modulation in spectroscopy.
  49. C

    Localized absorption of photons and carrier generation

    Perturbation theory predicts rates of transitions between eigenstates of the unperturbed Hamiltonian, which in the independent electron model for a crystal are nonlocal Bloch wave functions or linear combinations of them that extend throughout the crystal. However, photon absorption is...
  50. C

    How to find torque on planet carrier

    I have the following data in an epicyclic gear train: Angular speed on ring = 1500 rpm, teeth on ring = 30 Angular speed on sun = 3200 rpm, teeth on sun = 10 Angular speed on carrier = 1925 rpm, teeth on planets = 10 (The ratios of teeth are for simple calculation assumed 3: 1: 1 among...
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