What is Circulation: Definition and 82 Discussions

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. C

    Exploring the Physical Meaning of Circulation in Vector Fields

    Meaning of "circulation" Is there a physical meaning to circulation: \Gamma=\oint_{C}\mathbf{V}\cdot\mathbf{dl} For example, if the vector field represents a force field, the path integral denotes the work done on a particle moving along said path. Here, its is velocity. What meaning...
  2. R

    Circulation Motion - Airplane Loop

    Homework Statement A woman flying an airplane executes a loop in the air. Determine the value of the centripetal force acting on the woman flying the airplane when at the top of the loop? R = 380m V = 65 m/s M = 55kg Homework Equations Fc = mv^2/r The Attempt at a Solution I...
  3. C

    Using stoke's theorem to calculate circulation

    Homework Statement Use the surface integral in stoke's theorem to calculate the circulation of the filed F around the curve C in the indicated direction: F= x2y3i + j+ zk C; the intersection of the cylinder x2+y2=4 and the hemisphere x2+y2+z2=16, z>=0, counterclockwise when viewed from above...
  4. M

    Circulation of a stream function

    Homework Statement The stream function of a 2D incompressible flow is given by: \Psi=(\Gamma/2pi)*ln(r) Show that the circulation about a closed path about the origin is \Gamma and is independent of r. Homework Equations \Gamma=-\ointV dot ds The Attempt at a Solution So far I know that...
  5. D

    Possible title: Why Aren't NPSH Curves Published for Smaller Pool Pumps?

    Hey. At the moment, for my fluid mechanics course, i am working on an assignment where i have been instructed to design a basic fluid system which involves the use of an operating centrifugal pump. The system i have chosen is a pool circulation and filtration system. I have finished with...
  6. N

    Can a Circulation Integral Be Calculated Using a Scalar Field?

    Hello. I'm new to vector calculus and I had a question about the following integral: \int_{C} x dy please note that this is a circulation (I didn't know the tex-code for the little circle sign on the integral) They calculated this integral (for a specific curve) with the use of a line...
  7. M

    Circulation of a flow field around circle (x-1)^2+(y-6)^2=4

    Homework Statement A flow field on the xy-plane has the velocity components u=3x+y v=2x-3y Show that the circulation around the circle (x-1)^2+(y-6)^2=4 equals 4\pi Homework Equations The circulation \Gamma around a closed contour is: \Gamma=\int_C\vec{u}\cdot d\vec{s}The Attempt at a...
  8. L

    Understanding Circulation and Directionality in Vector Fields

    The circulation of a vector field is the closed line integral of the dot product between the vector and the infinitesimal displacement vectors along the curve. Therefore, the sign of circulation depends on which way around the curve you take the integral. This is all very well, but this...
  9. E

    Question about Thermohaline Circulation

    Hey guys, I have an assignment to do on Glaciation for university but I'm a bit lost with an aspect of the question and was wondering could anyone help. The aspect is how the Thermohaline Circulation is linked to the Quaternary Glaciation. I can't find any published articles about it from...
  10. W

    Computing Circulation in Pipe Flow using Velocity & Angular Direction

    I need to find the circulation for a flow in a pipe. I'm using the velocity in the angular direction (cylindrical coordinate system). Am I right in thinking that an ideal vortex is one where there is no vorticity? That would mean there is no circulation. It's strange, because the velocity is...
  11. A

    How Do You Calculate Blood Flow and Power in the Circulatory System?

    Homework Statement The blood transports substances required by the body and the waste products of metabolism. The blood contains many different constituents including red blood cells, white blood cells, platelets and protein. However, for calculation purposes, it is sufficient to treat blood...
  12. F

    Physical interpretation of circulation

    Can the circulation about some closed (rigid) path in a force field be interpreted as the work done by the force field on the path over an infinitesimal time?
  13. E

    Calculating Circulation of Vector G with Green's Theorem

    Homework Statement Use Green's Theorem to calculate the circulation of \vec{G} around the curve, oriented counterclockwise. \vec{G} = 3y\vec{i} + xy\vec{j} around the circle of radius 2 centered at the origin. Homework Equations The Attempt at a Solution...
  14. M

    Find the circulation using equation of motion

    Homework Statement v = ui + v j u = cos(x)sin(y) v = -sin(x)cos(y) Find the circulation around randa to the square defined by: x = y = [-0.5*pi,0.5*pi] Homework Equations Is there a rule that says which sides on the square that get i and whics gets -i when you draw the square?
  15. K

    CERN's Large Hadron Collider Makes Its First Beam Circulation

    So they didn't seem to collide any particles yet? I'm not too knowledgeable about this topic, but it must be something "landmark" as Google altered their logo to inform people about this. Anyways, there's a link to the article here...
  16. D

    Stoke's theorem to calculate circulation

    Homework Statement Use the surface integral in Stoke's Theorem to calculate the circulation of the Field F around the curve C in the indicated direction. F = (x^2)i + (2x)j + (z^2)k C: The ellipse 4x^2 + y^2 = 4 in the xy-plane, counterclockwise when viewed from above. Homework...
  17. T

    Do I need this circulation pump?

    The schematic shows a central heating system. I'm wondering if I can drop the twin pump? If each of the single pumps are powerfull enough to bring the water around through the heat exchanger then why do I need the twin pump?
  18. V

    Aircraft wings - Kelvins Circulation Theorem and the conservation of vorticity

    This is what I understand about Kelvin's Circulation Theorem 1)for inviscid (where the viscous forces are much LESS than inertial forces) AND uniform density flow, the circulation is conserved. 2)This implies (by some arduos vector calculus manipulations) that the vorticity of each fluid...
  19. U

    Medical Air bubble in blood circulation

    i remember once seeing on tv (fiction) how a man threatened another with a syringe and said he would inject the other with air and that 2 ccm would be enough to kill, if i remember correctly what happens if air gets into your circulatory system ? i imagine it would be ok until it is pumped...
  20. J

    Observations About Global Circulation Models

    I want to post some interesting quotes about global circulation models. Well, I believe they have potential I believe that the application of the theory is often misapplied. http://www.climateaudit.org/?p=483#comment-208656 http://www.climateaudit.org/?p=483#comment-209256...
  21. E

    Global Warming Impacts on Earth's Sea Level, Ocean Circulation, Oxygen Isotopes

    how would the Earth be affected by global warming in terms of the sea level , global ocean circulation, and oxygen isotopes?
  22. C

    Air Change Rate with Low Air Circulation

    I figured an example is the easiest way to explain my question. A 500-sq.ft laboratory with 9-ft ceiling includes an HVAC system delivering enough air volume for an air change (AC) rate of 10 AC/hr. However, both the air intake and exhaust are located in the ceiling, 18-ft apart. In this closed...
  23. F

    Plants, cell communication, digestion, and circulation

    Homework Statement I would like to have some of my homework problems checked. I looked in the book, and answered these the best I could. My answers are in bold. Thanks in advance for the help! Homework Equations N/A. The Attempt at a Solution 1. Which functional plant cells lack a...
  24. S

    Atmospheric Circulation and Seasonal Variation

    How does the summer solstice affect the position of Hadley cells? I know that the solar equator is 23.5 degrees North, which differs from the 0 degrees (as a solar equator) for the equinox. For the equinox in the N. hemisphere, there are three Hadley cells, or cells of circulation. The range of...
  25. H

    Exploring the Relationship Between Circulation and Lift in Potential Flow

    Hi all. I am revisiting things about potential flows. So, I believe the assumptions of potential flows shall be the irrotationality and the ignorance of viscosity. And I am studying the flow past a cylinder with and without circulation. Without circulation, there is no lift force but when...
  26. tandoorichicken

    Consequences of Debris in Circulation from Medical Devices

    At a high shear rate, red blood cells become elongated and oriented in one direction, facilitating smooth blood flow. However, at a high enough shear rate, the cells will become so strained that a part of the cell membrane pinches off. This often occurs in poorly designed medical devices that...
  27. T

    Design of hot water circulation system

    Here I've seen different solutions. Some people simply add a T to the hot water pipe from the heater and run the circulation pipe alongside the hot water pipe connecting the two near the end. They then connect a pump to this. I don't really see how this has any effect. Wouldn't the hot water...
  28. T

    Meridional Overturning Circulation vs. Thermohaline Circulation?

    What is the difference between Meridional Overturning Circulation and Thermohaline Circulation? Is it correct to say: THC is a principle - basically just the fact that colder and/or saltier water sinks because it's denser than warmer or less salty water. And that if some other factor such...
  29. Mk

    History of thermohaline circulation

    How could we possibly chart its history? The Greenpeace website cites ice core data as backing them up (what? no references? :smile:), but then we would have to have some gas isotope ratio that is used to pin down some quality.
  30. S

    Hypothetical Air Circulation on Earth: Balancing Radiation and Its Impact

    hypothetically, if incoming and outgoing radiation balanced at every point on earth, would there still be air circulation? What do you think?
  31. E

    Arabian Scientist Ebn Alnafees & Blood Circulation Discovery

    that ebn alnafees (who is an arabian scientist) was the first to discover the blood circulation
  32. K

    Does Accelerated Thermohaline Circulation Increase Tropical Water Vapor?

    When the flow of deep cold water in the atlantic speeds up what causes the amount of water vapour in the tropics to increase too.Could magma in the Earth be heating the sea water or hydrothermal vents - presumably sea currents would have to move to a hot spot or somehow encourage vents to...
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