shm Definition and Topics - 63 Discussions

The MIT Shared Memory Extension or MIT-SHM or XShm is an X Window System extension for exchange of image data between client and server using shared memory (/dev/shm). The mechanism only works when both pieces are on the same computer.
The basic capability provided is that of shared memory XImages. This is essentially a version of the ximage interface where the actual image data is stored in a SysV shared memory segment, and thus need not be transferred across the socket to the X server. For large images, use of this facility can result in some real performance increases.
Additionally, some implementations provide shared memory pixmaps. These are two-dimensional arrays of pixels in a format specified by the X server, where the image data is stored in the shared memory segment. Through use of shared memory pixmaps, it is possible to change the contents of these pixmaps without using any Xlib routines at all. Shared memory pixmaps can only be supported when the X server can use regular virtual memory for pixmap data; if the pixmaps are stored in the on-board memory of graphics hardware, an application will not be able to share them with the server.
In the 1.15 release of the X.org server the MIT-SHM extension gains two additional requests: 'X_ShmAttachFd' and 'X_ShmCreateSegment', to be able to pass shared memory through file descriptors from client to server and from server to client, reducing the number of copy operations further.

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  1. P

    Getting the equations of motion for this SHM problem

    Summary:: I have come across a situation where I seem to get different equations of motion for an oscillating system. Please do help me find out where I went wrong. *I am not asking how to solve the problem* I am going to consider 4 parts of the cylinder's motion, as listed below. (There is...
  2. Hamiltonian299792458

    Real life example of the composition of two SHMs with same angular frequency

    Under the topic of simple harmonic motion comes the composition of two SHM's with the same angular frequency, different phase constants, and amplitudes in the same directions and in perpendicular directions. composition of SHM's in same direction: say a particle undergoes two SHM's described by...
  3. Prabs3257

    Momentum conservation in SHM

    I first got the velocity of the combined mass with conservation of momentum and as it was in the mean position the velocity can be written as v = wA ( w= angular frequency , A = amplitude ) as we have to take it back to natural lenght i put A as the initial extension but i am getting a wrong ans...
  4. nuclearfireball_42

    Can I determine the phase angle of this equation by using the sin function?

    I've got the answer for (a). It's k = 0.78 N/m. I'm having problems with (b). I know that the equation of displacement in this case should either be : x(t) = Asin(ωt + φ) or x(t) = Acos(ωt - φ) where A = amplitude From what I understand, both the equation above should give the same result...
  5. Beelzedad

    How to know whether motion is simple harmonic motion or not?

    I am reading "Coulomb and the evolution of physics and engineering in eighteenth-century France". There it is said in page 152 para 1 that "Coulomb found that within a very wide range, the torsion device oscillated in SHM". My questions are: (1) By just looking at the time period of the...
  6. Prabs3257

    Change in the time period of a pendulum

    I tried taking log and then diffrentiate the standard equation for time period of a pendulum but i am not getting the correct answer
  7. warhammer

    B Shifting of a Cosine Curve with negative phase angle values

    Continuing on from the summary, the chapter has given a graphed example. We are shown a regular cosine wave with phase angle 0 and another with phase angle (-Pi/4) in order to illustrate that the second curve is shifted rightward to the regular cosine curve because of the negative value. Now, my...
  8. Shivang kohlii

    Equation of shm for different positions

    Homework Statement Write the equation for a particle in simple harmonic motion with amplitude a and angular frequency w considering all distances from one extreme position and time when it is at other extreme end. Homework Equations X = A sin (wt + ∆) ∆ = phase difference The Attempt at a...
  9. Celso

    Simple harmonic motion interpretation problem

    I'm in trouble trying to understand the expression ##t= \frac{1}{\omega} cos^{-1}(x/A)## that comes from ##x = Acos(\omega t)##, in which ##A## is the amplitude, ##t## is time and ##x## is displacement. When ##x = 0##, ##t = \frac{\pi}{2\omega} ##, shouldn't it be 0 since there was no movement?
  10. R

    Why is my thinking incorrect? -- Block and spring driven by a motor

    Homework Statement An oscillator consists of a block attached to a spring (k=400n/m). At some time t, the position (from equilibrium), velocity, and acceleration of the block are x= .100m, v= -13.6m/s, a= -123m/s^2. What is the frequency? mass of block? amplitude. Homework Equations position...
  11. Shivang kohlii

    Amplitude of a mass joined to a spring in the presence of an E-field

    Homework Statement A block of mass m having charge q placed on smooth horizontal table and is connected to a wall thorough an unstretched spring of constant k . A horizontal electric field E parallel to spring is switched on. Find the ampliture of the shm by the block. Homework Equations kx=...
  12. velvetmist

    I Why is x=e^(rt) in SHM?

    This may be a fool question, but i can't figure where does this come from. I would really appreciate if someone can help me. Thanks.
  13. thebosonbreaker

    Simple Harmonic Motion: why sin(wt) instead of sin(t)?

    Hello, I have recently been introduced to the topic of simple harmonic motion for the first time (I'm currently an A-level physics student). I feel that I have understood the fundamental ideas behind SHM very well. However, I have one question which has been bugging me and I can't seem to find a...
  14. G

    The phase of a simple harmonic motion

    Homework Statement How can I calculate the initial phase in a simple harmonic motion if I only have the amplitude, frequency and angular velocity as data? Homework Equations The formula of the position, in fact they ask me to do the formula that allows to know the elongation depending on the...
  15. Ari

    How to find period of a SHM concerning a cube and spring?

    1. Homework Statement The 4.00 kg cube in the figure has edge lengths d = 8.00 cm and is mounted on an axle through its center. A spring ( k = 1400 N/m ) connects the cube's upper corner to a rigid wall. Initially the spring is at its rest length. If the cube is rotated 4.00° and released, what...
  16. J

    Finding Tension force in a SHM Pendulum

    Homework Statement A 110 kg panda is riding on a 3.0 m long swing whose mass can be considered negligible. The highest point of its arc occurs when the swing makes a 20° angle with the vertical. What the magnitude of the total tension in the ropes of the swing at that point? m (mass of panda)...
  17. S

    Period of a mass spring system with 2 spring of same K(vert)

    A mass attached to a spring is oscillating in Simple Harmonic Motion. If an other spring of same sprinc constant is attached parrallel to the other spring, what is the period of this new system (as a function of the initial period). Here's what I did and have no idea if this is right: For the...
  18. V

    A mass is dropped on a plate that's suspended from a spring

    Homework Statement a load of mass m falls a height h onto a pan hung from a spring. if the spring constant is k and the pan is massless and m does not bounce, the amplitude of oscillation is Homework Equations F = - kx U = 1/2kx^2 The Attempt at a Solution mgh = 1/2kx^2, x =...
  19. V

    Amplitude of SHM of a spring hung from a ceiling

    Homework Statement A point mass of m = 20 kg is suspended by a massless of constant 2000N/m. The point mass is released when the elongation is 15cm.Find equation of shm Homework Equations F= - kx The Attempt at a Solution [/B] I'm not sure what this question is trying to say honestly...
  20. Z

    Mass of a vibrating string

    Homework Statement A second harmonic standing wave has the known quantities of Amplitude (max y at antinode) A, maximum velocity (y=0 at antinode) v, string length L, tension in the string T. Given that we know that it is second harmonic, we can assume that λ = L How can one determine the...
  21. A

    I Difference between transient and steady state solution

    In driven SHM, we ignore an entire section of the solution to the differential equation claiming that it disappears once the system reaches a steady state. Can someone elaborate on this?
  22. A

    I Solving the differential equations involving SHM

    What is the most satisfactory explanation for guessing certain solutions to the differential equations encountered in damped & driven SHM?
  23. N

    Simple Harmonic Motion: conceptual idea of angular frequency

    One of the conditions to distinguish Simple Harmonic Motion from other harmonic motions is by the relation that a∝x where x is the displacement from the point that acceleration is directed towards But what confuses me is the constant of proportionality introduced to this relation: ω2 ω is...
  24. J

    Simple Harmonic Motion

    Homework Statement Consider a Simple Harmonic Motion (SHM) for which, at time t = 1 s, the displacement is s=1 cm, the velocity is 2 cm s−1, and the acceleration is −3 cm s−2. Find the angular frequency, 4. amplitude, and phase constant for this motion. Homework Equations f=1/T...
  25. L

    Vmax of Block (SHM)

    Homework Statement A block with mass m=200g is attached to a spring with a elastic constant of k=5.0 N/m. The block is pushed at a distance x=5.00cm of its equilibrium position, in a surface with no friction. Then its dropped of that position. Assume for t=0s that the block is at rest. What is...
  26. F

    Differential equation for a pendulum

    Homework Statement A simple pendulum is formed by a light string of length ##l## and with a small bob ##B## of mass ##m## at one end. The strings hang from a fixed point at another end. The string makes an angle ##\theta## with the vertical at time ##t##. Write down an equation of motion of...
  27. R

    Determine the angular frequency of the system in SHM

    Homework Statement Determine the angular frequency of the system in the image. The cable is ideal but the pulley is not. I will present the same solution but with different coordinate axes. For some reason they arent the same and neither of them are correct. Given data: R is the radius of...
  28. F

    Simple Harmonic motion

    Homework Statement The question is uploaded. The Attempt at a Solution I have completed the whole question, however, stuck on the last part. How to find the value about which ## \rm \small \theta## now oscillates? A source stated that ## \rm \small \alpha## is the value about which ## \rm...
  29. S

    Block on Spring SHM, Finding angular frequency

    Homework Statement An "ideal" spring with spring constant 0.45 N/m is attached to a block with mass 0.9 kg on one end and a vertical wall on the other. The floor has negligible friction, and you give the block a push and then let go. You observe that the block undergoes simple harmonic motion...
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