Circulation Definition and 83 Threads

A newspaper's circulation is the number of copies it distributes on an average day. Circulation is one of the principal factors used to set advertising rates. Circulation is not always the same as copies sold, often called paid circulation, since some newspapers are distributed without cost to the reader. Readership figures are usually higher than circulation figures because of the assumption that a typical copy of the newspaper is read by more than one person.
In many countries, circulations are audited by independent bodies such as the Audit Bureau of Circulations to assure advertisers that a given newspaper does reach the number of people claimed by the publisher. There are international open access directories such as Mondo Times, but these generally rely on numbers reported by newspapers themselves.
In many developed countries, newspaper circulation is falling due to social and technological changes such as the availability of news on the internet. On the other hand, in some developing countries circulation is increasing as these factors are more than cancelled out by rising incomes, population, and literacy.

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  1. DaveC426913

    To circulate air, fan points in or fan points out?

    Got a friend with a boat he's storing over the winter. He wants to discoruage misture and mold build up by keeping air circulating. He puts a box fan in the companionway, (and presumably opens the fore hatch). All other things being equal, is it better to point the fan into the companionway...
  2. A

    Calculating the circulation of the Field F along the borders of this region

    Greetings The exercice consist of calulating the circuitation of the Field F along a the borders of the region omega my problem was how they found that y goes from 0 to h ( for 0 it´s clear but the mystery for me is h) Thank you!
  3. M

    Potential Flow Theory: Circulation and the Kutta-Jukowski Theorem

    Hi, I just had a quick question about conventions in potential flow theory: Question: What is the convention for ## \Gamma ## for the streamline ## \Psi = \frac{\Gamma}{2\pi} ln(\frac{r}{a} ) ## and how can we interpret the Kutta-Jukowski Theorem ## Lift = - \rho U \Gamma ##? Approach: For the...
  4. M

    Potential Flow Theory: Circulation and the Kutta-Jukowski Theorem

    Homework Statement:: What is the convention for ## \Gamma ## for the streamline ## \Psi = \frac{\Gamma}{2\pi} ln(\frac{r}{a} ) ## and how can we interpret the Kutta-Jukowski Theorem? Relevant Equations:: ## v_{\theta} = - \frac{\partial \Psi}{\partial \theta} ## [Mentor Note -- moved from the...
  5. R

    Circulation of water in a cylindrical reservoir

    Fig1: Fig2: We haven't covered this topic yet, but they expect us to solve it and I'm not 100% sure what I'm doing. a) ##C_r =\oint{\vec{v}*\vec{dl}} = \int{\omega*r*dl} = \omega*\int{r*r*d\phi} = \omega*r^2*2pi## b) Now here I begin to struggle. If v is constant, can I simply pull it out of...
  6. C

    Arbitrary Circulation Calculation with Fourier Series

    Homework Statement Homework Equations The Attempt at a Solution I am stuck trying to figure out why there are three different alphas and why in the equation we are supposed to use has a theta and what that means. If I can set up the Fourier series I can properley I know how to solve it for...
  7. A

    Is there a difference between work and circulation?

    These two things seem to be exactly the same (even down to the same formula), so I'm having difficulty understanding why they are two different terms. Is circulation just the work done as you go around a circle once?
  8. J

    Extension Projectile Motion and Circulation motion questions

    Hi, I was wondering if anyone has any links or documents of some challenging projectile motion and circular motion questions. Also, if you have any regarding 'Energy' and roller coasters and pendulums and Hooke's law they would be great too. I am in year 11 and am looking to do some extra study...
  9. T

    Find magnetic flux density B circulation in closed contour

    Homework Statement Find magnetic flux density B circulation in closed contour. The countour consists of square with a perimeter of 4b. It includes a square conductor with a perimeter of 4a. A homogenic current flows through a conductor with a current density of j. Homework Equations...
  10. Aafia

    Why white blood cells and red blood cells are destroyed?

    Why do white blood cells die and what cause them to destroy within a few (20-30) hours? I have an other question also that if red blood cells remain within capillaries, veins and arteries then how do they pass onto liver cells for the breakdown or they die within veins, capillaries and arteries?
  11. Carter Green

    I What Forces Affect Liquid Flow in a Circular Pipe?

    Hi I am trying to understand what forces are at work to slow a liquid flowing in a circular pipe As an example the above torus pipe fully filled with an incompressible low viscosity liquid. This is rotated until the fluid achieves solid body rotation and then the pipe is suddenly stopped...
  12. J

    Why do you get pressure drop in central circulation?

    What is the reason that the pressure drops in the central circulation?especially if you go from arteries to arterioles you get a huge pressure drop. If you look what is changing if you go from arteries to arterioles then it is that you get many many branches this leads to an increase of total...
  13. S

    Circulation of a Mag field around a wire, what is the angle?

    Circulation of a magnetic field = closed loop integral ∫c B ⋅dl = μ0I B is mag field strength, dl is small line element, I is current Im imagining both B and dl point in the same direction from the diagram. So the dot product here, I picture as cosθ = cos0 Is that correct way to...
  14. I

    Fluid circulation around a closed curve

    I know that the circulation is defined as the counter clock wise integral around the closed curve of the flow velocity component along the curve but what is its meaning in real life? I mean what does circulation actually refer to in real life? Also could someone explain the above image? What is...
  15. A

    Is Kelvin's Circulation Theorem Applicable to Vortex Tube Conservation?

    (Edited to make an answer more likely) So first let's quickly summarize what this is. If you have some closed curve c(t) around a set of fluid elements, Kelvin's circulation theorem says that the circulation around this curve is constant as the curve and its corresponding fluid elements move...
  16. Conservation

    Circulation of a triangular region

    Homework Statement Find the circulation (line integral) of y2dx+x2dy for the boundary of a triangular region contained within x+y=1, x=0, and y=0. Homework Equations Green's theorem The Attempt at a Solution I think I actually already got the solution; I used the Green's theorem to get the...
  17. R

    Height limitation for natural circulation thermosiphon

    Suppose I have an overhead tank that heats hot water by natural circulation via a thermosiphon (& a Heat Exchanger with some source of waste heat), is there a limitation on how tall this loop can be? e.g. Can there be an elevated tank at 30 feet with a heat exchanger at ground level that heats...
  18. P

    Circulation Around an Airfoil and Starting Vortex

    Homework Statement Using Kelvin’s circulation theorem, find the qualitative and quantitative relation between the circulation around an airfoil and the circulation of the starting vortex. Homework Equations Kelvin's circulation theorem: DΓ/Dt=0 The Attempt at a Solution I don't really know...
  19. V

    How to calculate the circulation flow in makeup water

    Actually i have to calculate the make up water capacity of cooling tower . M= E+B+W . but while calculating the particulars , i am needing the circulation flow rate . i searched it in internet also but it simply showing 18000 so getting confused . Is it 18000 a constant or anything there to...
  20. D

    Counterclockwise Circulation vs. Clockwise Circulation

    Homework Statement [/B] Consider F = (y - z)i + (z - x)j + (x + z)k Find circulation of F in the clockwise direction as seen from above, around the boundary of surface S defined by z = 4 - x2 - y2 0 ≤ z ≤ 4 Homework Equations ∫∫ ∇xF • k dA The Attempt at a Solution ∇xF = i - 2j - 2k...
  21. D

    This implies that the circulation around the ellipse ##C## is also zero.

    Homework Statement F = y2z3i + 2xyz3j +3xy2z2k Find the circulation of F in the clockwise direction as seen from above, around the ellipse C in which the plane 2x + 3y - z = 0 meets the cylinder x2 + y2 = 16 Homework Equations ∫ F (dot) dr = ∫∫ (∇xF) (dot) k dA The Attempt at a Solution z...
  22. H

    Why is there circulation around a wing?

    Homework Statement From my notes: "In an irrotational flow, Γ = 0 for any curve lying wholly within the fluid. But circulation around a wing (airflow) is possible! Why?" The Attempt at a Solution The obvious answer is that the air around the wing isn't irrotational. But that seems a bit too...
  23. marellasunny

    Is the condenser of a E-vehicle cooled by liquid circulation?

    I've noticed that a FEW of the electrical vehicles have no front grill. I am quite surprised that they do not have one, because the condenser of the AC unit needs to have heat taken away from it (in other words, the condenser needs a heat exchanger). So, in view of the fact that E-vehicles don't...
  24. J

    Another vector fields in terms of circulation and flux

    Other laws in terms of circulation and flux Why others vector fields no are studied like the magnetic and electric fields? In other words, why others vector fields, like the gravitational and the hydrodynamic, haven't "supreme laws" based in the circulation/flux or curl/divergence?
  25. J

    Is the current a kind of circulation?

    I know what is circulation by a mathematical point of view, but in the reality (in the physical world), what is circulation? I'm thinking that the electrical current through of a circuit, that the water current through of an pipe or of an river, that the water vortex formed over a drain or that...
  26. J

    Can Circulation be Computed in a System with an Open Path of Integration?

    Exist circulation in a system/circuit/vector field/anything where the path of circulation is open? Is possible to compute the circulation of a system/circuit/vector field/anything with an open path of integration?
  27. mudweez0009

    Natural Circulation and Decay Heat

    Homework Statement I am having issues with some problems relating to a plant theoretically shut down on natural circulation, and calculating the core ΔT and natural circulation flow rate.. Can anyone provide some equations or theory I could use to assist me? I'm not familiar with this...
  28. J

    Circulation Definition: Understanding Positive, Null, and Negative Circulation

    1st which is the math definition for circulation (##\Gamma = \int_s \vec{f}\cdot d\vec{s}##)? And 2nd, what means positive, null and negative circulation?
  29. A

    Vector circulation. Stokes, Gauss and maybe more?

    Hello. My first time posting here. So... My question is kinda hard to explain but I will try to. So we all know about the Kelvin-Stokes theorem (not talking about manifolds here) : And we also know about Ostrogradsky/Gauss Theorem ...
  30. T

    Air circulation question [Image attatched]

    Hello, My name is Tom and I had a theoretical question about general air pressure and circulation. i have attached an image to diagram the system I am describing. In this closed system loop there is one part of a loop filled with water and the other part filled with air at a higher...
  31. P

    Finding the circulation of a vector field

    Homework Statement Can someone guide me through solving a problem involving the circulation of a vector field? The question is as stated for the vector field E = (xy)X^ - (x^2 + 2y^2)Y^ , where the letters next to the parenthesis with the hat mean they x y vector component. I need to find...
  32. D

    Circulation & Flux: Confirmation Needed | Differentiate1

    Here's my work: http://i.imgur.com/9ik31P5.png I need confirmation that the vector fields I found for parts 1) and 2) are correct. I also need to figure out how to find the flux in part 2) when the problem doesn't give any boundaries to evaluate. For part 1), the answer can be found by...
  33. D

    Does the answer for part (c) really have to be 0?

    Here's my work typed in Microsoft Word: http://i.imgur.com/jWPqBDh.png I have trouble believing the answer is 0 for part c. All I did was use the curl of F from part a and dot it with dr which came out to be 0.
  34. P

    Compute circulation of vector around the contour

    Homework Statement Compute the circulation of the vector a = yi+x2j - zk around the contour L: {x2 +y2 = 4; z = 3}, a) directly and b) via the Stokes Theorem. Plot the contour and show its orientation. Homework Equations Stokes theorem is \ointF.dr = \int∇ X F . n dS The Attempt...
  35. skate_nerd

    How Do Perpendicular Vectors Around a Triangle Sum to Zero?

    Homework Statement So a, b, and c are points in the plane. Let nab, nbc, and nca be vectors perpendicular to ab(vector), bc(vector), and ca(vector) respectively, and point towards the exterior of the triangle abc. Also, |nab|=|ab(vector)|, |nbc|=|bc(vector)|, and |nca|=|ca(vector)|. Show...
  36. R

    How do you compute the circulation of this fluid (path integrals)

    Homework Statement A fluid as velocity field F(x, y, z) = (xy, yz, xz). Let C denote the unit circle in the xy-plane. Compute the circulation, and interpret your answer.Homework Equations The Attempt at a Solution Since the unit circle is a closed loop, I assumed that ∫ F * dr = 0 (the ∫ symbol...
  37. J

    Calculate the circulation of vector field

    Hello there, I've got a vector field which you can see here: Sketch of the vector field . It is: \vec{v} = \cos(x)\,\sin(y)\vec{i}-\sin(x)\,\cos(y)\vec{j} Say I want to find the circulation around the square formed by -\frac{\pi}{2} \, \leq x \leq \, \frac{\pi}{2} and -\frac{\pi}{2} \...
  38. J

    Thin vortex filament with constant circulation; find velocity components

    Homework Statement In a xyz cartesian coordinate system, a thin vortex filament with constant circulation Gamma, forms a square (in the xy plane), with each side of the square having length L. You are told that an infinitesimal segment del (vector) of this filament induces an infinitesimal...
  39. H

    Problem understanding the differential form of the circulation law

    I've encountered a problem in learning about the curl of a vector field. (My learning material is the "Div, Grad, Curl and all that" from H.M. Shey.) Introduction to problem: The curl of a field F is defined as: ∇×F = i (∂Fz/∂y - ∂Fy/∂z) + j(∂Fx/∂z - ∂Fx/∂x) + k(∂Fy/∂x - ∂Fx/∂y)...
  40. M

    Zero curl but nonzero circulation

    The vector field \vec{F} = <\frac{-y}{x^2 + y^2},\frac{x}{x^2 + y^2},0> has a zero curl, which means its circulation is zero. However \int \vec{F}.d\vec{s} around a unit circle on the xy plane is equal to (+/-)2\pi and not zero Is it because F is undefined at (0,0)? No, because Stoke's...
  41. C

    Circulation of a 3d vector field

    Homework Statement consider the vector field v(x,y,z)=(-h(z)y,h(z)x,g(z)) wherer h:R->R and g:R—>R are differentiable .Let C be a closed curve in the horizontal plane z=z0.show that the circulation of v around C depends only on the area of the reion enclosed by C in the given plane and h(Z0)...
  42. I

    Calculating Rotational Speed on a Giant Wheel

    Homework Statement A giant wheel, 40m in diameter, is fitted with a cage and platform on which a man can stand. The wheel rotates at such a speed that when the cage is at X (as shown) the force exerted by the man on the platform is equal to his weight. The speed of the man is: X is located...
  43. U

    MHB Compute the circulation of F along C

    Hi, This is my first post. So if I made any mistakes that is the way I asked the questions, kindly let me know. The work done so far Circulation: C {0,0,1} to {1, pi,1} C eq: {y=pi*x, z=1} dr={dx, pi*dx, 0} F={cos(y/z), -x/z*sin(y/z),xy/z^2*sin(y/z)} F.dr = -dx [dot product and...
  44. H

    Cold shutdown that doesn't require coolant circulation?

    "cold shutdown" that doesn't require coolant circulation? I was wondering what is preventing a plant being built that can be truly shut down and not require coolant circulation. Is it that efficiency would be reduced to unacceptable levels?
  45. 6

    Flux & Circulation Homework: Find Values & Prove Non-Zero Flux

    Homework Statement Let F(x,y) = ( P(x,y), Q(x,y)) be a vector field that is continuously differentiable along the closed smooth curve C : x2+y2 = 1. Moreover let -F(x,y) = F( -x, -y)≠ 0 and P(x,y) = -P(-x,y) and Q(x,y) = Q(-x,y). Determine all the possible values of the circulation...
  46. C

    Medical Understanding Air Embolus and Blood Circulation

    I have never really thought why an air embolus can restrict the passage of blood, until now, and I don't really understand. Why can't the circulation pressure just push the air embolus forward until it is eventually expelled in the lungs? Or why can't it dissolve the embolus? In a plant is...
  47. H

    CLIMATE physics-general atmospheric circulation

    Homework Statement I'm trying to find sketches that demonstrate ,the general circulation patterns of the atmosphere and the cells in atmosphere of a planet.3 cases must be considered:a slow rotating ,a fast rotating and a non rotating planet. Homework Equations The Attempt at a...
  48. B

    Circulation around a plane wing.

    After looking into the lift force i hve been able to calculate most of the things i know. I have however been told that i need to use circulation and vorticity to show that the air flows faster over the wing than below it. I need to show this mathematically by derviving an equation but i am...
  49. S

    Circulation over a triangle in R^3

    I have attached a file with all needed information including the function and path of integration. My work seems right to me, but the correct answer is a^2. Will someone please take a look and show me where my misstep is.
  50. M

    Fluid momentum and Natural circulation in Nuke reactors

    How is the net driving pressure difference within a PWR a function of T and H delta P = delta T(Core) * g * partial Rho(T, P(RCS))/partial T * delta H I get how this correlates to the pressure differential and is found with bernoulli's equation but how does the temperature dependence get...
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