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Topic: Thermal radiation


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In the News (Wed 26 Jun 19)

  
  Night Vision, Objective Lens, Image Intensifier, Fibro Optic, Night Vision Photography, How Night Vision Works
Thermal images are normally fl and white in nature, where fl objects are cold and white objects are hot.
In this method, a device that is sensitive to invisible near infrared radiation is used in conjunction with an infrared illuminator.
Infrared radiation spans the wavelengths between approximately 750 nm (0.75 microns) and 1 mm (1000 microns).
www.hownightvisionworks.com   (0 words)

  
  CRR 285/2000 Thermal radiation criteria for vulnerable popu...
CRR 285/2000 Thermal radiation criteria for vulnerable popu...
The many factors that affect human response are considered, and the differences between the response of children and the elderly to those of an 'average' population are identified.
Concludes that existing dangerous dose criterion for thermal radiation for vulnerable populations is reasonable.
www.hse.gov.uk /research/crr_htm/2000/crr00285.htm   (97 words)

  
  Thermal Radiation & Planck's Spectral Radiancy
The spectrum of the thermal radiation from a hot solid body is continuous; that is, it emits electromagnetic radiation in a continuous range of wavelengths (or frequencies), over a rather large band of allowed wavelengths.
Likewise, in considering ``the radiation problem,'' it is useful to introduce the concept of ``an ideal radiator." For such an object we assume that the spectrum of the emitted thermal radiation depends only on the temperature of the radiator and not on the material or the nature of the surface.
The radiation is emitted by the interior walls of the cavity, and becomes quite mixed before it manages to find the small hole to escape; as a result of this it depends very little on the actual material of the body, or its surface.
panda.unm.edu /courses/finley/p262/ThermalRad/ThermalRad.html   (2241 words)

  
  Thermal Radiation
Thermal radiation is the radiant energy (heat and light) that is emitted by the fireball.
Thermal radiation travels at the speed of light and persists as long as the fireball is luminous.
The emission rate of thermal radiation from a highyield weapon is slower than that from a low-yield weapon.
www.tpub.com /dc32/102.htm   (597 words)

  
 Thermal radiation - RecipeFacts   (Site not responding. Last check: )
Thermal radiation is electromagnetic radiation from the surface of an object which is due to the object's temperature.
Infrared radiation from a common household radiator or electric heater is an example of thermal radiation, as is the light emitted by a glowing incandescent light bulb.
Thermal radiation is generated when heat from the movement of charged particles within atoms is converted to electromagnetic radiation.
www.recipeland.com /facts/Thermal_radiation   (759 words)

  
 2.3 Thermal Radiation   (Site not responding. Last check: )
Thermal infrared remote sensing shares the advantage of all remote sensing in that information can be obtained at a distance and non-intrusively.
Usually, a wide-band thermal infrared signal detected from objects is dominated by the object's thermal emission, which in turn is determined largely by the object's temperature.
Accordingly, the primary uses of thermal infrared imaging are associated with the temperature of objects, ranging from bacteria to human skin to planet atmospheres.
www.uni-kiel.de /castle/ch2/s2l2p055.htm   (503 words)

  
 High resolution ground & airborne thermal imaging surveys from DHR Consultancy Services Ltd
When considering thermal imaging equipment, the anticipated temperature of the object under examination should be used to give an indication of the most suitable band to use.
The most common type of thermal detector uses the pyro-electric effect in which the temperature change of the element causes a change in the charge present on the device electrodes.
A typical thermal imaging facility will clean and dry the air during the charging of bottles and the air will also be passed via a filter assembly when being subsequently fed to the detector.
www.thermal-survey.co.uk /t_tech.htm   (3404 words)

  
 The Astrophysics Spectator: LTE Radiation   (Site not responding. Last check: )
An atmosphere is said to be in local thermal equilibrium, often abbreviated as LTE in the astronomy literature, when at each point the electrons and ions are described by a thermal energy distribution, but the temperature of that distribution varies from point to point.
Radiation that passes through such an atmosphere attempts to come into thermal equilibrium with the plasma as it flows through the photosphere into space.
For a hot radiation field passing through a cooler atmosphere, which characterizes most of the emission through the atmosphere of a star, this interaction produces absorption lines, which are dips in the continuum spectrum.
www.astrophysicsspectator.com /topics/radiation/LTE.html   (958 words)

  
 Experiment 1
Thermal radiation is the energy emitted by a body as result of its finite temperature.In contrast to heat transfer through convection and conduction, radiation heat transfer does not require a medium and can occur in a vacuum.
Whether thermal radiation is visible, and at what color, is a function of the portion of the radiation that falls within the visible spectrum.
Not only is the total amount of thermal radiation emitted by a surface - described by the Stefan-Botzmann’s law - a direct function of temperature, how this energy is distributed over the thermal spectrum as a function of wavelength, is also a related to the surface temperature.
www.eng.fsu.edu /~alvi/EML4304L/webpage/experiment_1.htm   (1785 words)

  
 Atmospheric Radiation
Thermal motion of the charged particles in matter causes electromagnetic radiation, called thermal radiation from its cause, though it is no different from other electromagnetic radiation.
For solar radiation at 5750 K, the maxima are at 505 nm and 887 nm, respectively.
If you start with a uniform radiation spectrum, first the centres of the lines are absorbed and removed from the beam, then the wings of the lines, and in a complex way that depends on the details of the spectrum (which for a long time were not accurately known).
www.du.edu /~etuttle/weather/atmrad.htm   (2457 words)

  
 About Thermal Imaging (Infrared Thermography)
Thermal imagers with temperature measurement capability, called sometimes "Radiametric Imagers" and Quantitative Thermal Imagers" are used also in many Non-destructive testing situations and some of the professional societies for non-destructive testing around the world, such as the American Society for Non-destructive Testing (ASNT) in the USA, have adopted Infrared Testing as a sanctioned testing method.
Thermal imaging devices provide the observer with instruments that can collect (just like a video or still camera) and convert the thermal infrared radiation emitted (and also reflected) by objects into images that can be seen on a view screen or computer display.
Thermal Imaging practiced in the context of medical dignostics is also growing, but there it is known as "Thermology" to perhaps distinguish it from the practices not involving a person's health.
www.temperatures.com /thermalimaging.html   (1641 words)

  
 Laws of thermal transfer – radiation   (Site not responding. Last check: )
The energy, radiated from a body in certain direction is established by Lambert’s law according to which the flow radiated from an absolutely fl body is proportionate to the flow radiated in direction of the normal toward the surface and the cosinus of the angle between them.
The radiation is the principal thermal transfer between the heater and the heated body in the chamber of the electro-resistance furnace which determines the key role of its correct description.
When a thermal screen between two bodies with different temperatures is available, the radial flow between them changes depending on the number of the screen, the coefficient of radial emission, the materials of the bodies and the area of the surfaces.
www.geocities.com /bdimitrov_project/myproject/Laws/radiation.htm   (1698 words)

  
 Thermal Radiation - Search Results - MSN Encarta   (Site not responding. Last check: )
Thermal Radiation, radiation of heat and light in the form of rays or waves.
At the same time that Bohr and Rutherford were developing the nuclear model of the atom, other experiments indicated similar failures of classical...
Radiometer, instrument for detecting and measuring the intensity of radiant thermal energy, particularly infrared radiation.
encarta.msn.com /Thermal_Radiation.html   (93 words)

  
 Thermal Radiation Calorimeter
If a specimen is heated only by thermal radiation and the input power is evaluated properly, the thermophysical properties such as specific heat and thermal conductivity of the materials can be determined.
The radiation calorimeter is consisted of the system in which a heater and a disk-shaped specimen are mounted in a vacuum chamber.
The specimen is heated and cooled slowly by radiation from the heater for the heat capacity measurement.
www.nda.ac.jp /~hisano/Rad-Lab.htm   (895 words)

  
 Nanoscale Thermal Radiation Labo
Near-field radiation may play a significant role in the heat transfer process between the SPM cantilever tip and the surface over which it scans, due to photon tunneling through evanescent modes and surface-waves (such as plasmon or phonon polaritons).
The purpose of this research is to investigate the nanoscale thermal radiation both theoretically and experimentally.
To better understand micro/nanoscale thermal radiation, a theoretical study on the direction of the energy flow was performed by examining the group velocity upon refraction [1].
www.me.gatech.edu /~zzhang/Research_KH.htm   (1007 words)

  
 Lecture 3 - Thermal Radiation, Brightness & Intensity (1/19/99)
The spectrum of this "thermal" radiation depends on the thermal distribution of velocities and thus kinetic energies of the atoms in the material.
Thermal radiation is also called flbody radiation because it is most easily calculated for a "fl" substance that absorbs all light that falls on it (and also emits back the same light but in thermal equilibrium, and thus possibly at a different wavelength as we will see).
The thermal spectrum of photons is continuous, a smooth function of wavelength, in contrast to the spiky line emission at the discrete energy levels of atoms.
www.aoc.nrao.edu /~smyers/courses/astro12/L3.html   (1168 words)

  
 Radiation Theory in Heat Transfer
Radiation heat transfer is concerned with the exchange of thermal radiation energy between two or more bodies.
Thermal radiation is defined as electromagnetic radiation in the wavelength range of 0.1 to 100 microns (which encompasses the visible light regime), and arises as a result of a temperature difference between 2 bodies.
The heat transferred into or out of an object by thermal radiation is a function of several components.
www.efunda.com /formulae/heat_transfer/radiation/overview_rad.cfm   (264 words)

  
 Radiation
As a consequence, thermal energy transfer may occur within the fluid by emission and absorption of EMR, a process called "internal radiation." Because of thermal expansion and buoyancy effects, internal radiation may couple to the motion of the fluid.
is employed to obtain conditions (at high pressure) where the radiation pressure gradient may be strong enough to influence the flow, and thus enable a comparison of flows with and without significant radiation pressure effects.
The thermal properties will be used to verify the 1-d transport equations, to quantify spatial and temporal deviations from steady and/or 1-d profiles and to quantify the amplitude and temporal spectrum of the disturbances.
www-scf.usc.edu /~davidcla/rift2.htm   (2754 words)

  
 Nuclear Weapon Thermal Effects
Large amounts of electromagnetic radiation in the visible, infrared, and ultraviolet regions of the electromagnetic spectrum are emitted from the surface of the fireball within the first minute or less after detonation.
In addition to the high temperature of the nuclear fireball, the flbody radiation is emitted in a characteristic two-peaked pulse with the first peak being due to the radiating surface of the outrunning shock.
Both theory and experiment indicate that the dominant thermal pulse can be adequately represented by a flbody at a temperature between 6,000° and 7,000° K, which places the peak of the spectrum near the boundary between the ultraviolet and the visible regions of the spectrum.
www.fas.org /nuke/intro/nuke/thermal.htm   (1103 words)

  
 National Terror Alert Response Center » Nuclear
Another penetrating form of radiation is gamma rays, which are energetic photons.
In addition to being intensely bright, this radiation is intensely hot (hence the name “thermal”).
One of the effects of nuclear weapons detonated on or near the earth’s surface is the resulting radioactive fallout.
www.nationalterroralert.com /nuclear   (1361 words)

  
 Radiation Laws
Generally, flbody conditions apply when the radiator has very weak interaction with the surrounding environment and can be considered to be in a state of equilibrium.
The primary law governing flbody radiation is the Planck Radiation Law, which governs the intensity of radiation emitted by unit surface area into a fixed direction (solid angle) from the flbody as a function of wavelength for a fixed temperature.
The behavior of flbody radiation is described by the Planck Law, but we can derive from the Planck Law two other radiation laws that are very useful.
csep10.phys.utk.edu /astr162/lect/light/radiation.html   (0 words)

  
 Thermal Radiation Overview   (Site not responding. Last check: )
is the wavelength of the radiation in nm.
The MCVP uses a CCD that is sensitive to visible radiation, thus the intensity in the visible spectrum is expanded in the Fig 2.
There is a large difference between the intensity radiated within the visible wavelengths as the temperature changes.
alfven.princeton.edu /projects/ThermalRad.htm   (144 words)

  
 Thermalphysics.org - The Little Heat Engine - Essay   (Site not responding. Last check: )
Thermal conduction is the process whereby heat energy is transferred within an object without the absolute displacement of atoms or molecules.
Thermal conduction is that process which tries to bring the internal structure of the solid to thermal equilibrium.
Thermal conduction and radiative emission remain tied to the energy associated with the vibrational degrees of freedom, while convection becomes associated with the energy within the translational and rotational degrees of freedom.
www.thermalphysics.org /heat/heatenginepict.html   (4414 words)

  
 Thermal Radiation   (Site not responding. Last check: )
Radiation emitted by any object with a temperature greater than absolute zero.
A thermal spectrum occurs because some of the heat energy of the object is converted into photons.
In general, a thermal spectrum depends not only upon the temperature, but also upon the composition of the object, its shape, its heat capacity, and so forth.
www.astro.virginia.edu /class/hawley/glossary/thermalrad.htm   (67 words)

  
 Radiation
Heat radiation (as opposed to particle radiation) is the transfer of internal energy in the form of electromagnetic waves.
She was exposed to a monstrous dose of electromagnetic radiation from a nuclear blast.
GWPs are calculated as the ratio of the radiative forcing that would result from the emissions of one kilogram of a greenhouse gas to that from emission of one kilogram of carbon dioxide over a period of time (usually 100 years).
hypertextbook.com /physics/thermal/radiation   (1440 words)

  
 THERMAL FACILITIES - Επιτοίχια Θέρμανση Μαρμάρου
Thermal radiation is an infrared radiation which, when in contact with a solid body (i.e.
The surfaces of both the ground and the sea reflect as well, through atmosphere, an infrared radiation, which depends mainly on their temperature that is the heat, which they have previously accumulated under the influence of the sun's radiation.
The principle of climatic conditioning of a space with thermal radiation (Tepidarium) is traced from the 5 century BC.
www.thermal.com.gr /en_marmaro.htm   (2004 words)

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