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. L

    Parallel Equipment Grounding Conductors, Short Circuit

    I am seeking direction, information, resources and thoughts on the following subject. The common interpretation of the National Electrical Code does not allow you to use multiple smaller equipment grounding conductors in place of one larger one (except in a few cases such as a cable assembly...
  2. B

    I Parallel plate particle acceleraton questions

    Suppose there exists a pair of parallel plates with a voltage between them. These plates have a certain amount of energy stored in the electric field between them (E=1/2*C*V^2). Now we fire a fast (~5,000,000 m/s) beam of protons through the plates (parallel to the electric field) such that the...
  3. DaynaClarke

    Resistors in Parallel or Series?

    Given that they're all on the same branch, I had assumed that they were in series with one another. But with the middle resistor having being on the middle of three branches, it looks parallel. Like I said, I have a feeling it's in series (making the answer 3R). This question is from a past...
  4. Harperchisari

    The energy conservation issue with parallel charged plates with a hole.

    A while back I thought of an issue with parallel charged plates. Imagine this: a set of opposite charged resistive plates with holes in the center. In theory, there is a finite amount of energy required to push a positive charged particle through the hole in the positive plate (in theory it...
  5. M

    Coil and resistor in parallel -- How to calculate the phase angle?

    Hello. So I have a coil and a resistor in parallel connection. It is powered by alternating current. I have to calculate angle between voltage and current, what is the formula? I know the reactive resistance in coil, I know resistance of resistor, voltage across both of them and amps flowing...
  6. davidfur

    MPI parallel code speed-up sucks

    Hey guys, I parallelized my code, written in C++, with the MPI library. Unfortunately, the speed-up I get saturates at x6, with increasing number of cores. Whereas, in theory, the speed-up should really be nearly linear. To understand where the bottlenecks come from, I drilled down the code to...
  7. S

    Temperature profile between two parallel plates

    Homework Statement Imagine two parallel plates at distance ##L##. One of them at constant temperature ##T_H## and the other one at ##T_C##. Media between the plates is air. Find ##T## as function of distance from the plate with ##T_H## in steady state. Homework Equations Navier - Stokes Heat...
  8. Rakesh Kumar Jaiswal

    Charge induced on parallel plates if a charge between plates

    Two infinite conducting plates 1 and 2 are separated by a distance l. A point charge q is located between the plates at a distance x from plate 1. Find the charges induced on each plate. Many of the places this problem has been solved by considering an infinitely large plate in place of the...
  9. mohammed othman

    Force due rotation about axis parallel to centroidal axis

    in the case of a disc rotating about the centroidal axis and having an unbalanced mass we used the formula F(force)=m x r x w^2, where r is the distance from the center to the center, m mass of the unbalanced, w rotational speed in the case of a disc rotating about axis parallel to the...
  10. A

    I Parallel transport of tangent vector....(geodesic)

    https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.damtp.cam.ac.uk/user/hsr1000/part3_gr_lectures_2017.pdf&ved=2ahUKEwi468HjtNbgAhWEeisKHRj9DNEQFjAEegQIARAB&usg=AOvVaw3UvOQyTwkcG7c7yKkYbjSp&cshid=1551081845109 Here in page 55 it is written that geodesic is a curve whose tangent...
  11. PainterGuy

    Electric field outside a parallel plate capacitor

    Hi! Could you please help me with the queries below? Thanks a lot. Question 1: My question is about the field outside the plates of parallel plate capacitor. It is said that the field(s) between positively and negatively charged plates gets added up but the field(s) outside the plates gets...
  12. Shivang kohlii

    Time constant for parallel RC circuit

    Homework Statement Question 6. Homework Equations Time constant = RC The Attempt at a Solution I think answer should be 1/2 RC as Rnet = 1/2R and to convert it to single resistance form we should first find Rnet But the answer is coming out to be RC . How? << Corrected Image added by...
  13. Jason-Li

    Parallel Capacitance - Power Factor Question

    Homework Statement A 50 kW load operates from a 60 Hz 10 kV rms line with a power factor of 60% lagging. Determine the capacitance that must be placed in parallel with the load to achieve a 90% lagging power factor. The Attempt at a Solution For Z at 0.6pf S=P/pf = 50000/0.6 = 83333.33VA I =...
  14. P

    Transistor and an LED in parallel

    Hi! I'm new to EE and was wondering if this: https://imgur.com/a/lSgNl52 would cause the LED to light up, or would the transistor short the circuit? (I forgot to add the arrow on the diode and I'm too lazy to fix it. And I just realized that the resistor is wrongly placed.)
  15. F

    Reconciling an apparent contradiction about Parallel Circuits

    I'm fairly sure that everything I wrote in the diagram in the attached photograph is consistent and accurate, but I don't understand how this can be. The rules involved seem to contradict each other. I hope you people can reconcile this for me. It's my understanding that in the diagram in the...
  16. Shivang kohlii

    Current through source in AC circuit with R & LC in parallel

    Homework Statement In the circuit diagram shown , Xc = 100 ohm , XL = 200 ohm , R = 100 ohm , the effective current through the source is ? Homework Equations Z= √( R^2 + ( XL - Xc)^2) Vrms = Irms/ ZThe Attempt at a Solution I tried to draw the phaser diagram and calculate the relation...
  17. C

    B Parallel Spacetimes: Matter & Antimatter Separated?

    Is it possible for two plains of parallel spacetime to exist separated by some sort of void? One being antimatter and one being matter with the void bringing neutral territory. Like a piece of paper between two big magnets.
  18. Krushnaraj Pandya

    Current through capacitors in parallel

    Homework Statement In the given circuit at t=0 S is closed then at time t, i1/i2 a) is constant b) increases c) decreases d) first increases then decreases Homework Equations V=IR, Q=CV The Attempt at a Solution At t=0, capacitors act like closed switches, so I2=2I1, where I2 and I1 are the...
  19. archaic

    Equivalent Resistance of Parallel Resistors

    I did this for fun, if you want to do it in an unconventional way, this would be useful in programming. For ##n## resistors in parallel: $$R_{total}=\frac{\prod_{i=0}^{n-1} R_{i}}{\sum_{i=0}^{n-1}(\prod_{j=0}^{n-2} R_{i+j \mod n})}$$
  20. G

    Two voltmeters in parallel measure these different voltages

    Homework Statement I'm currently studying induction law and circuits with inductors. I came however with the following circuit: [1]: https://i.stack.imgur.com/ghaiE.png Homework Equations 3. The Attempt at a Solution [/B] Now my text says the following: "Unlike what your intuition might...
  21. Celso

    Nullifying Lorentz Force on Proton Moving in Parallel Direction

    Homework Statement A proton moves with a speed ##v = 3 \cdot 10^5 \frac{m}{s}## in the parallel direction to ##i+k##. A magnetic field of ##1T##, in the ##i+j+k## acts over it. Which electric field must we apply in this region so that the Lorentz force over the proton is null? Homework...
  22. cookiemnstr510510

    Potential of parallel plate capacitor

    Homework Statement I have attached a problem from within the chapter of my book. I have a question regarding my highlighted part. My question: Is the reason they are saying E= -Q/(ε0A) because they defined the positive "s" axis to the right? and since E is pointing from right to left we say...
  23. Brett Anthony

    Batteries in Parallel, One Reverses Polarity

    So, some time after getting a new car the batteries on my FOB died. So I went in and replaced them, two CR2016's was all that was needed (on top of each other in parallel). No more than a month later I noticed the battery felt like it was dying already (light not as strong, delay on the actions...
  24. ItsTheSebbe

    Finding the bandwidth of a parallel RLC circuit (+MATLAB)

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  25. C

    Parallel Universes: Multiverse vs Many Worlds - Splits?

    Hi, sorry - forgive me for posting (I am not much of a science guy but I am still interested). I am just watching a documentary (I know not a great source for scientific information - but it got me thinking). In the documentary it talks about the many worlds theory (which I believe is different...
  26. Shivam2112

    I want to fit 2 radiators in parallel....

    What are the downside for it ,also can i fix 2 bike radiators (cross flow) by rotating them by 90 like top to down flow
  27. Curiosity 1

    Engineering Three-phase circuit: Why Z_Ye is parallel with Z_Δ?

    Homework Statement This problem is taken from Fundamentals of Electric Circuits (chapter 12, problem 15). Homework Equations As shown in the first blue box, I have trouble seeing why after the conversion, Z_Ye will be parallel with Z_Y. I think it's because the voltages 'emitting' from the...
  28. R

    Potential difference between charged parallel plates

    So we know that the E-field between two parallel plates is constant and that the potential difference between the plates is just the E-field times the distance between the plates. Let's say we're moving a positive charge from a negatively charged plate to a positively charge plate ( or near)...
  29. V

    Find Angular Velocity for Moving Particle Parallel to x-Axis

    Homework Statement A particle is moving parallel to x-axis in the positive direction with velocity v such that at all the instants the y -axis component of its position vector is constant and is equal to 'b'. Find angular velocity about origin. Homework EquationsThe Attempt at a Solution I...
  30. E

    Python Convert a FOR loop to parallel processes

    Hi, I know that Python supports parallel programming. I think it can be used in my case but not sure how. Basically I have this for loop out = [] for value in vec: out.append(func(value)) where func is some function that takes value as an argument. The different values in vec are...
  31. S

    I Difference between parallel and antiparallel spins?

    What is the difference between parallel and antiparallel spins for a pair of nucleons? My understanding is that nucleons have a strong tendency to pair - proton with proton, neutron with neutron, proton with neutron. When they pair their spins either: cancel (spins pair antiparallel) pairing...
  32. E

    B In parallel universes, everything that can happen happens, but why?

    Hello, on quantum theory of parallel universes. It seems quite ridiculous to me, in quantum mechanics everything, that's not forbiden by rules happes. Are there some theories why it may be ? Or is it to early to even speculate about that. Elon musk said, that there is chance bilion to one, that...
  33. M

    Fan Performance and Pressure Distribution in Parallel Centrifugal Fans

    I have two different capacity centrifugal Induced Draft fans.I attach them in parallel.They both pull air through the same duct and deliver the exhaust to the same stack. Is the pressure at the inlet and outlet of both fans same? What is the fan curve for such a combination?
  34. Z

    I Why Am I Getting a Reading of 0.3 Amps When Connecting AA Batteries in Parallel?

    Hey, so I tried to get a lot of Amps and primarly my tool are batteries, so I have 3 batteries that I have connected together in parallel (+ with the + and then - with the -) they are 1.6V Kirkland batteries that are all brand new. So when I took a machine I have to calculate the voltage and...
  35. D

    Engineering Combination circuit with Series & Parallel light bulbs

    Homework Statement One 18 watt lamp and two 60-watt light bulb are plugged into a 120V circuit. For either DC or AC, the two bulbs are connected each other in parallel and in series with the lamp in the same circuit. Calculate; i. the current flow through each light ii. the total...
  36. A

    Is the source in parallel or series with the resistor?

    Thank you for your time and effort. It is much appreciated. 1. Homework Statement I have attached the problem with the solution to this thread. Basically, the problem asks to construct the circuit model for a generic device by using the data of terminal current and voltage measurements. From...
  37. J

    Two parallel diodes in a circuit

    Homework Statement Homework EquationsThe Attempt at a Solution I am not quite sure how to deal with the two diodes in parallel . How do we know what is the potential applied across the two diodes so as to decide which one is conducting ?
  38. B

    Maximizing Vacuum Power: Understanding the Effects of Parallel Vacuum Sources

    I have two vacuum sources each pulling 1 inHG. If I connect the vacuum sources to a Y-connector, with identical sized hoses, so that each pulls on one tip of the Y, will I get 2 inHG vacuum on the remaining hose, or will I get 1 inHG with more cfm? Thank you, B
  39. P

    Will the maximum discharge current double for two parallel batteries?

    Hello. Say I have a high powered device that draws continuous 18A. 3.7v And I have one 3.7v 3500mah 18650 with a maximum continuous discharge of 10A, I know the battery will overheat and will most likely get damaged or shorten its life, or even catch fire. But If I have another battery (same...
  40. A

    Finding the Optimal Combination of Resistors for a Desired Total Resistance

    Homework Statement I'm asked to find a combination of resistors (parallel and/or series) that uses resistors of 25 Ω, 100 Ω, 50 Ω, and 50 Ω. They should add up to give a total resistance of 62.5 Ω. Homework Equations Req for parallel = 1/R1 + 1/R2 + ... Req for series = R1 + R2 + ... The...
  41. D

    Batteries in series, parallel, and internal resistance

    Homework Statement Three identical batteries are first connected in parallel to a resistor. The power dissipated by the resistor is measured to be P. After that, the batteries are connected to the same resistor in series and the dissipated power is measured to be 4P (four times larger than for...
  42. Z

    Current through parallel cells with unequal EMFs

    1 Two cells are connected in parallel by joining the terminals together so that they both face in the same direction. One of the cells has emf 6.0 V and internal resistance 3.0 Ω, and the other cell has emf 4.0 V and internal resistance 2.0 Ω. An 8.0 Ω resistor is connected between the...
  43. S

    Calculating induced voltage in two parallel conductors

    Say I have two parallel conductors that are both L long and d distance apart (center to center). I run AC power of frequency f and RMS voltage V through one conductor. That current will create a fluctuating magnetic field which will pass through the the other conductor and generate a voltage...
  44. T

    I Beltrami flows have zero parallel gradients?

    In the following wiki article for Beltrami flows, it is stated that the nonlinear terms are identically zero. I can easily prove the terms are equivalent and thus cancel one another, to yield the linear equation. But after a bit of algebra, I don't see why the terms are zero themselves? Why...
  45. C

    RC Circuit with parallel resistor

    Homework Statement A circuit contains a capacitor of capacitance C, a power supply of emf E, two resistors of resistances R1 and R2 , and a switch S2 . Resistor R1 is in series with the power supply and R2 is in parallel with the capacitor and the power supply. S2 switches the branch that...
  46. GoodPost

    Short-circuited Resistance in Parallel with Reactance

    Dears, Please help me out with this. The attached figure is an equivalent circuit of an induction machine. I'm trying to find the current (Is). It's assumed that the core losses are neglected and hence Rc =0. If this is the case, then Rc (short-circuited) is in parallel with jXm. What's the...
  47. wolfsloth

    Parallel Circuits - Joining 2 branches together

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  48. M

    Charge distributions of two infinite parallel plates

    Homework Statement Two infinitely large conducting plates with excess charge 2Q and 3Q are placed parallel to one another, and at a small distance from one another. How are the charges 2Q and 3Q distributed? You may assume that infinitely large sheets of charge produce electric fields that are...
  49. Ignitia

    Magnetic Force with Parallel currents

    Homework Statement A circuit with current I has two long parallel wire sections that carry current in opposite directions. Find magneticfieldatapointPnearthesewiresthatisadistance a from one wire and b from the other wire as shown in the figure. Homework Equations B=μo*I / 2πR The Attempt...
  50. J

    AC voltage across a parallel branch

    Homework Statement Homework EquationsThe Attempt at a Solution I am assuming that the given value of voltage applied is an RMS value . Same voltage is applied across both the branches . In the upper branch the net resistance is the sum of capacitive reactance of the capacitor and...
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