Parallel Definition and 1000 Threads

Parallel computing is a type of computation in which many calculations or processes are carried out simultaneously. Large problems can often be divided into smaller ones, which can then be solved at the same time. There are several different forms of parallel computing: bit-level, instruction-level, data, and task parallelism. Parallelism has long been employed in high-performance computing, but has gained broader interest due to the physical constraints preventing frequency scaling. As power consumption (and consequently heat generation) by computers has become a concern in recent years, parallel computing has become the dominant paradigm in computer architecture, mainly in the form of multi-core processors.Parallel computing is closely related to concurrent computing—they are frequently used together, and often conflated, though the two are distinct: it is possible to have parallelism without concurrency (such as bit-level parallelism), and concurrency without parallelism (such as multitasking by time-sharing on a single-core CPU). In parallel computing, a computational task is typically broken down into several, often many, very similar sub-tasks that can be processed independently and whose results are combined afterwards, upon completion. In contrast, in concurrent computing, the various processes often do not address related tasks; when they do, as is typical in distributed computing, the separate tasks may have a varied nature and often require some inter-process communication during execution.
Parallel computers can be roughly classified according to the level at which the hardware supports parallelism, with multi-core and multi-processor computers having multiple processing elements within a single machine, while clusters, MPPs, and grids use multiple computers to work on the same task. Specialized parallel computer architectures are sometimes used alongside traditional processors, for accelerating specific tasks.
In some cases parallelism is transparent to the programmer, such as in bit-level or instruction-level parallelism, but explicitly parallel algorithms, particularly those that use concurrency, are more difficult to write than sequential ones, because concurrency introduces several new classes of potential software bugs, of which race conditions are the most common. Communication and synchronization between the different subtasks are typically some of the greatest obstacles to getting optimal parallel program performance.
A theoretical upper bound on the speed-up of a single program as a result of parallelization is given by Amdahl's law.

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  1. binbagsss

    Parallel Axis Theorem derived from the Displaced Axes Theorem.

    I am trying to attain the parallel axis theorem from the displaced axes therom. I have the displaced axes thorem stated in this form: \hat{I}=\hat{I}com+M\hat{A} -Where Rc is the position of the centre of mass position- -Where \hat{}is the inertia tensor of a rigid body wrt to rotations...
  2. DarkGuardsman

    Several Voltage Source in Parallel

    About: I'm currently working on programming a basic circuit simulator for a game. One of the things i don't have a sure answer on is parallel voltage sources. I understand from what I've read so far that when two sources are in parallel the lower of the two gets overloaded. If they are the same...
  3. U

    Dielectric half-filled parallel plate capacitor

    Question taken from Griffiths Pg 185, Problem 4.19: For part (b): -Why are the electric fields the same whether in dielectric or in air? In part (a), they are clearly different! -Why is σ_{tot} = ε_{0}E = ε_{0}\frac{V}{d} -In calculation of capacitance, why is the total charge (\frac...
  4. L

    Parallel Axis Theorem problem help

    Homework Statement This is moreof a conceptual question regarding the parallel axis theorem and area. Lets say I have a solid rectangle with length L, and Width W. I cut out a circle of radius R at the center. When calculating the Total Area moment of inertia of the hollow region where the...
  5. kira506

    Forces acting on two parallel wires carrying current which producing B

    I want to know how to calculate the force , I know the formula and such but its just that I'm not sure about the Length part , I mean if Wire1 is longer than Wire2 ,then should I take the common length between them , or just substitue with the total length ? , should F1on2=B2I(delta)l or B2I1L1
  6. A

    Rectifier and parallel ac sources

    I am new to engineering so i might not understand the concept well , but i want an ac source to provide current only in one way , so i can connect them in parallel. I have 2 AC sources one with a 100 V output and one with a 120 V output , i need to connect them in parallel so i can get a 220 V...
  7. T

    Breakdown in parallel plate capacitor with dielectric

    Homework Statement Two related questions (from Electromagnetics by Notaros) The dielectric of a parallel-plate capacitor has two homogeneous parts, referred to as dielectric 1 and dielectric 2. The boundary surface between the parts is flat and parallel to the capacitor plates. The dielectric...
  8. T

    Energy of a parallel plate capacitor homework

    Hi all "A parallel plate capacitor in which plates of area A are separated by a distance d, has a capacitance C = \frac{Aε_{0}ε_{r}}{d} It is charged to a pd V. Neglecting edge effects, derive an equation for the electric field E in the capacitor, and show that the energy stored per unit volume...
  9. S

    What does Q-factor and Dynamic resistance of a parallel resonance

    Homework Statement What does Q-factor and Dynamic resistance of a parallel resonance circuits mean?Homework Equations The Attempt at a Solution In general, their performance is measured by a dimensionless parameter named quality factor Q, which characterizes the sharpness of the resonant peak...
  10. N

    True or False, Parallel Axis Theorum

    Homework Statement I am doing an assignment where I have this (easy) true/false question. The parallel axis theorem can be used to find moments of inertia of an object about arbitrary axes, provided the moment of inertia about a perpendicular axis through the centroid of the object is...
  11. mrspeedybob

    Multiple parallel plate capacitor question.

    Consider a capacitor with 4 parallel plates and 3 dielectric insulators arranged like this...+I-I+I- The insulator in the center has an equal amount of + and - charge on each side of it so shouldn't the electric field across this insulator be almost zero? If I constructed this capacitor with...
  12. F

    Understanding Planewaves Bouncing Parallel Plates (Waveguide)

    Hi, I'm rather confused as to how this diagram in my book. I know that in order for a mode to propagate, a standing wave must be formed in the waveguide, and this happens above some cutoff frequency that one designs for. What I don't understand is, below cutoff, what happens? I don't...
  13. AakashPandita

    Proof of parallel axis theorem.

    Everybody says that the distance ,between the two axis, used in the formula, is perpendicular. But in the proof it was a hypotenuse. It was not perpendicular.
  14. F

    Parallel Plate Waveguide Loss Dependence On Mode

    Hi, The attenuation resulting from puting a signal into a parallel plate waveguide is dependent on the excited mode. Why does the TM mode have greater attenuation than the TE mode? I can see in the maths it 'works out' to be that, but what would be a more conceptual/physical reason? Is the...
  15. S

    Path of a block suspended by two parallel cords

    I have an argument with classmates about the trajectory that the block will have (circle, ellipse, something else...). The configuration is similar to this image. http://minireference.com/_media/physics/momentum-bullet-speed-block.jpg?w=400 Initially, the block will move horizontally...
  16. A

    Energy radiated by a parallel plate capacitor

    Homework Statement A parallel-plate capacitor C , with plate separation d , is given an initial charge ±Q_{0}. It is then connected to a resistor R, and discharges, Q(t)=Q_{0} e^{-t/RC} 2 (a) What fraction of its energy Q_{0}^{2}/2C does it radiate away? Homework Equations The equations for...
  17. U

    Component of vector parallel to boundary while calculating divergence

    So when we calculate divergence (especially referring to the gauss divergence theorem), why aren't the components of the vector field parallel to the boundary considered? I mean even of, say fluid, is traveling parallel to the boundary when it comes out, fluid is exiting, or diverging out...
  18. F

    Parallel Plate Waveguide Basic Functionality Issue

    Hi, I think I'm missing something with how a parallel plate waveguide works. In the picture I've shown below, there intensity of the E-field change depending on how far across the waveguide it is. While I know that this has to happen in order for anything to propagate, I don't quite...
  19. L

    Geometric phase of a parallel transport over the surface of a sphere

    I have this question on the calculation of the geometric phase (Berry phase) of a parallel transporting vector over the surface of a sphere, illustrated by Prof. Berry for example in the attached file starting on page 2. The vector performing parallel transport is defined as ψ=(e+ie')/√2...
  20. PhizKid

    Total charge in a circuit/determining parallel or series

    In this image, C1 is 1 microfarad and C2 is 3 microfarads and both capacitors are charged with a potential difference of V = 100V. S1 and S1 are closed. The solution says this is in parallel, but I don't see how it is. It looks like it's set up in series to me. But even if it is in...
  21. W

    Moment of Inertia Using Parallel Axis Theorem

    Homework Statement Q is the edge length of the cube. The moment of inertia of the cube about an axis passing through its center and the center of two opposing faces is (1/6)mQ^2 (PCM in the diagram). Use the parallel axis theorem to find the moment of inertia if the axis is along one face of...
  22. V

    Using parallel propagator to derive Riemann tensor in Sean Carroll's

    Hello all, In Carroll's there is a brief mention of how to get an idea about the curvature tensor using two infinitesimal vectors. Exercise 7 in Chapter 3 asks to compute the components of Riemann tensor by using the series expression for the parallel propagator. Can anyone please provide a...
  23. O

    Final Velocity in parallel plate capicator?

    1. The plates of a parallel plate capacitor are separated by a distance (4cm). A point charge of magnitude (q=2e) (3.2*10^-19 C) is fired horizontally through a small hole in the positive plate of the capacitor. The charge is fired with speed (8.5 *10^5 m/s) and, upon reaching point M (located @...
  24. E

    LaTeX Parallel Lines between Two Blocks (Latex)

    Hello all, I have two blocks, and I want to draw multiple parallel lines between them. This is the Latex code I have \documentclass{article} \usepackage{tikz} \usetikzlibrary{shapes,arrows,fadings, shadows} \usepackage{amsmath,bm,times} \begin{document} \pagestyle{empty}...
  25. pellman

    How do we parallel transport a vector?

    Given a curve c(τ) with tangent vector V, a vector field X is parallel transported along c if \nabla_V X=0 at each point along c. Let x^\mu(\tau) denote the coordinates of the curve c. In components the parallel transport condition is \frac{dx^\mu}{d\tau}\left(\partial_\mu X^\alpha +...
  26. bibo_dvd

    A Question about Voltage Sources in Parallel

    Hello Guys ! My Question : in this photo i found That Total Resistance will be = 7 ohm . and I2 = 12 / 7= 1.71 A and I1 = 0.5 * I2= 0.5 * 1.71= 0.85 A I can't understand why I1= 0.5 I2 ?? and why it isn't the same of I2 ?? here is the photo Thank you Guys ! :))
  27. H

    Green's Function and Parallel Plate Waveguide

    Homework Statement A parallel plate waveguide has perfectly conducting plates at y = 0 and y = b for 0 ≤ x < ∞ and -∞ < z < ∞. Inside that bound, the waveguide is filled with a dielectric with k as a propagation constant. The Green's function to be satisfied is \nabla^2G + k^2G =...
  28. bibo_dvd

    A Question about Parallel Resistances

    Hello Guys ! My question is : why in these photos the ohmmeter reads the total resistance ?? I mean why in (a) the ohmmeter can't read the 8 ohms resistance ? and Why in (b) the ohmmeter can't read the (2||10 ) resistance ? Thank you Guys ! :))
  29. W

    How can compensation values be effectively combined in parallel Kahan summation?

    Hi PF, I am working on a parallel reduction code to sum up approximately 1 million 32-bit floating point numbers. The serial part running on each processor uses Kahan summation, no problems there. My problem is that this produces several sum/compensation pairs that now need to be added...
  30. K

    Understanding why R_E is in parallel with g_m in a BJT

    Homework Statement Why is R_E in parallel with 1/g_m1? I drew the small signal model but it does not make sense to me Homework Equations The Attempt at a Solution
  31. V

    Capacitance of two parallel plate capacitors

    Homework Statement Two square metal plates with sides of length 0.1 m are separated in vacuum by 10-3 m. Find their capacitance. Homework Equations C = Q/V For a parallel plate capacitor: C = E0A/L The Attempt at a Solution If A is supposed to be the length of the metal...
  32. A

    Detecting if resistances are parallel or series in complex circuits

    I know how to detect when resistors are arranged in parallel or series arrangement and I can also find their equivalent resistance in simple circuits or when resistances are connected in form of triangle but what happens when the arrangement is complex like this : Which resistors are...
  33. D

    Circuit with 2 components. Series or Parallel?

    Homework Statement Say I have a circuit with only 2 components, a battery and a capacitor. Is this circuit considered series or parallel? What about a charged capacitor and an uncharged one? Does the fact I have an oscilloscope connected to the capacitor to read the voltage across it affect...
  34. A

    Identifiying Parallel And Series Connections

    Homework Statement I'm having a bit of a problem identifying series and parallel connections of resistors in some new circuits I've been exposed to, like the ones posted below. I'd be very grateful if anyone could give me some pointers or tips, or perhaps link me to some videos/explanations...
  35. J

    Capacitor charge in series and parallel circuit

    Homework Statement Three capacitors, with capacitances C1 = 4.0 μF, C2 = 3.0 μF, and C3 = 2.0 μF, are connected to a 12 -V voltage source, as shown in the figure. What is the charge on capacitor C2 ?Homework Equations Q=VC Q = charge V = voltage C = capacitance Ceq = equivalent...
  36. U

    Finding impedance of rlc parallel ckt

    in most of the books i have seen that while finding an impedance for an parallel RLC circuit first they find the individual admittance of each of the element the after summation of these they take reciprocal to find the impedance why is it done like that can't we find the impedance in a normal...
  37. W

    Surface intersected by line parallel to x-axis

    Problem: Consider ## I=\int_S \vec{v} \cdot d \vec{S}=\int_S \vec{v} \cdot \hat{n} dS##, where S is a surface that is intersected once by an line parallel to the x-axis. Show that dS=\frac{|\nabla f|}{\partial f/ \partial x}dy \ dx, and that therefore, I=\int_S \vec{v} \cdot \frac{\nabla...
  38. D

    Definition of Parallel Vectors in Vector Spaces

    I was discussing with a friend of mine whether the zero vector is parallel to all other vectors. We came to the conclusion that it probably is but we do not know the formal definition of parallel. What is the formal definition of parallel? Wolfram says that two vectors are parallel iff their...
  39. Y

    Coulomb's Law And Electric Field between 2 Parallel Plates

    Homework Statement A uniform electric field exists in the region between two oppositely charged plane parallel plates. A proton is released from rest at the surface of the positively charged plate and strikes the surface of the opposite plate, 1.59cm distant from the first, in a time...
  40. B

    V of 2 parallel lines makes cylinders

    Homework Statement Expanded from Griffith's (3rd ed) #2.47 Infinitely long wires parallel to x-axis carrying ±λ charge densities intersect the y-axis at ±a. A) Calculate V(x,y,z) if V(0,0,0)=0 B)Show that the equipotential surfaces are circular cylinders. Locate the axis and calculate...
  41. P

    Find vectors that are perpendicular & parallel

    Homework Statement 1)Give a unit vector a) in the same direction as v=2i +3j b)Perpendicular to v 2) a) Find a vector perpendicular to the plane z=2+3x-y b)Find a vector parallel to the plane Homework Equations The Attempt at a Solution 1) a) Method 1: u=v/||v|| so i...
  42. E

    Solving for Current in Parallel Batteries with Different Voltages

    I want to know how we can find out the net voltage of a circuit where two batteries with different voltages are connected in parallel... Let's consider the problem stated below... If I have a circuit where there are 2 batteries in parallel(5V & 15V)... And it is connected in series with...
  43. A

    Engineering Series and parallel R-L-C turned circuits

    Homework Statement A coil of inductance 0.20 H, resistance 60 ohms is connected in parallel with a 20 μF capacitor across a 20 V, variable frequency supply. Determine: 1. the resonant frequency 2. the dynamic resistance 3. current resonance 4. Q- factor at resonance Is anyone there...
  44. P

    For what values of a are teh vectors parallel

    For what values of "a" are teh vectors parallel Homework Statement v = 5a i -3 j w = a^2 i -6 j Homework Equations The Attempt at a Solution My first thought was too get the unit vectors of both and set them equal to each other and solve for a, but that got messy. (5a i-...
  45. adjacent

    Why does bulbs glow bright in parallel?

    I have searched google and got no satisfying answer.Someone said that the overall resistance is less so as the voltage is same,the current increases.I don't think this is correct because the current for a single bulb is reduced.Can you give a satisfying answer?:confused:
  46. B

    How to Calculate Equivalent Resistance with Kirchhoff's Laws?

    okay i have this somekind of a paradox in the circuit below voltage around R0 and R2 is supposed to be equal now if it is equal , wouldn't that mean that the current will not pass through the middle vertical wire ? and if it doesn't then this means that the resistors are now connected in...
  47. B

    Simple circuit - parallel resistors

    Simple circuit -- parallel resistors Homework Statement i am asked to find two or more resistors having the same voltage across their terminals , the answer is R2 and R0 , but i want to know why , note that there are no known values(they might or might not be equal i have no idea ) for R nor...
  48. M

    Oppositely Charged Parallel Plates

    Homework Statement Two oppositely-charged parallel plates are separated by a distance of 0.03m. a. What is the strength of the electric field between the two plates if it takes 2.4x10^-19 J of energy to move an electron from one plate to the other. b. What is the acceleration of that...
  49. C

    Parallel and perpendicular part of a vector

    Homework Statement Resolve the force F into a) a part perpendicular to AB and b) a part parallel to BC Homework Equations a dot b = ab*cos(θ) The Attempt at a Solution I attached my attempt in the .pdf file. For some reason it is wrong. I don't understand how my reasoning is...
  50. andyrk

    Understanding Parallel Springs & the Equal Extension Assumption"

    When springs in parallel are replaced by a new spring of a new effective spring constant, for the proof of this, i.e keff=k1+k2 Why do we assume the extension in the springs to be equal?
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