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Topic: Joule heating


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In the News (Wed 22 Oct 14)

  
 Metastability and Dynamic Phase Transitions of a Vortex Lattice in Pure 2H-NbSe2
The effect of Joule heating is detected by comparing the response of the vortex lattice to fixed amplitude current steps of short (10ms) and long (4s) duration, where the Joule heating is negligible and saturates respectively.
While this heating can be accompanied by interesting physical phenomena such as the hotspot effects [1-4], it also causes difficulties in analyzing transport experiments and in determining the physical properties related to the vortex motion, especially at high dissipation levels [5-13].
Joule heating can be reduced significantly by using short pulsed currents [5-7,14] or by applying the current at high ramping rates [8,12].
www.physics.rutgers.edu /~eandrei/PRB-01ab.htm   (2678 words)

  
 Joule heating - Wikipedia, the free encyclopedia
In electronics, and in physics more broadly, Joule heating or ohmic heating refers to the increase in temperature of a conductor as a result of resistance to an electrical current flowing through it.
At an atomic level, Joule heating is the result of moving electrons colliding with atoms in a conductor, whereupon momentum is transferred to the atom, increasing its kinetic energy (see heat).
Joule heating is named for James Prescott Joule, the first to articulate what is now Joule's law, relating the amount of heat released from an electrical resistor to its resistance and the charge passed through it.
en.wikipedia.org /wiki/Joule_heating   (186 words)

  
 FDA/CFSAN: Kinetics of Microbial Inactivation for Alternative Food Processing Technologies -- Ohmic and Inductive ...
Ohmic heating (sometimes also referred to as Joule heating, electrical resistance heating, direct electrical resistance heating, electroheating, and electroconductive heating) is defined as a process wherein (primarily alternating) electric currents are passed through foods or other materials with the primary purpose of heating them.
Ohmic heating is distinguished from other electrical heating methods either by the presence of electrodes contacting the food (as opposed to microwave and inductive heating, where electrodes are absent), frequency (unrestricted, except for the specially assigned radio or microwave frequency range), and waveform (also unrestricted, although typically sinusoidal).
Inductive heating may be distinguished from microwave heating by the frequency (specifically assigned in the case of microwaves), and the nature of the source (the need for coils and magnets for generation of the field, in the case of inductive heating, and a magnetron for microwave heating).
vm.cfsan.fda.gov /~comm/ift-ohm.html   (4298 words)

  
 Joule and the Conservation of Energy
James Joule was born in 1818, the second son of a prosperous brewer in Manchester, England.
Joule also calculated that the water just beyond the bottom of a waterfall will be one degree Fahrenheit warmer than the water at the top for every 800 feet of drop, approximately, the kinetic energy turning to heat as the water crashed into rocks at the bottom.
Joule’s work was so impressive that his provincial origins were forgiven, and by the late 1840’s he was regularly presenting papers to the British Association and the Royal Society.
galileo.phys.virginia.edu /classes/152.mf1i.spring02/Joule.htm   (1250 words)

  
 Development Focus: New Models for Microfluidics   (Site not responding. Last check: 2007-10-16)
Joule heating is caused by electric currents in the buffer solution.
Heat generation makes it difficult to maintain the uniform and controlled buffer temperatures that are important for minimizing dispersion during temperature sensitive chemical reactions such as DNA hybridization.
Generally, the ability to dissipate the heat generated by electric, current is what limits the strength of the applied electric field and thus the maximum achievable flow rate.
www.flow3d.com /newsletters/04/summer04nmf.htm   (231 words)

  
 Joule's law - Wikipedia, the free encyclopedia
Joule's law (also known as Joule effect) is a physical law expressing the relationship between the heat generated by the current flowing through a conductor.
Where Q is the heat generated by a constant current I flowing through a conductor of electrical resistance R, for a time t.
The heating effect of conductors carrying currents is known as Joule heating.
en.wikipedia.org /wiki/Joule's_law   (145 words)

  
 Behavioral Modeling   (Site not responding. Last check: 2007-10-16)
Joule heating leads to cross-sectional non-uniformities in the buffer temperature and electrophoretic mobility, which contributes to broadening (dispersion) of the species band.
Joule heating can be significant in the presence of high electric fields, which are desired for improving electrophoretic separation speed and resolving power.
There can also be appreciable Joule heating in microchannels of relatively large cross-sectional dimensions, which are at times used to allow longer detection cells, higher detectability, reduced adsorption of analytes to channel walls, and less stringent requirements on sample injection schemes.
www.andrew.cmu.edu /user/yiw/Behavioral_model.html   (1686 words)

  
 joule - Hutchinson encyclopedia article about joule   (Site not responding. Last check: 2007-10-16)
One joule is approximately the amount of energy used to pick up an apple from the floor and place it on a table 1 m/3 ft high.
A joule is also the work done in one second by a current of one ampere at a potential difference of one volt.
The joule replaces the calorie (one calorie equals 4.2 joules).
encyclopedia.farlex.com /joule   (186 words)

  
 Joule   (Site not responding. Last check: 2007-10-16)
Joule was not as joule silly joule as joule it is not only a traditional unit widely used in astronomy.
Joule table of contents of any page joule in joule the cellar of joule his research was proportional to exactly joule grams.
Joule his conclusion was divided joule into joule a wealthy manchester brewing.
joule.leadingbo.com   (151 words)

  
 Steady-state thermal characteristics of AMR read/write heads used in tape storage drives
Because current passes through the sensor, it is subject to joule heating, dependent on both the geometry of the sensor and the thermal conductivities of its material.
Heat flow away from the head substrate was found to be significantly higher when the tape is moving than when it is stationary, and a simple model is developed to describe the heat dissipation of the substrate as a function of tape velocity.
The flow of heat from the substrate to the tape can be understood with a heat-flow analysis in which heat flows from the head substrate to the moving magnetic iron-oxide particulates on the tape surface.
www.research.ibm.com /journal/rd/474/lee.html   (6614 words)

  
 Joule Heating Lab - 2002
Joule is given credit for determining the mechanical equivalent of heat.
The temperature of the liquid was measured as work was done on the system, and Joule discovered that the temperature increase was the same as if the same amount of heat had been added to the system.
Rather than repeat Joule's effort by converting mechanical energy into heat, we will test whether the energy of a flowing electrical current causes a similar response.
physics.ham.muohio.edu /p184s04/joulheat02.htm   (915 words)

  
 Thermal Analysis: Joule Heating
Joule heating occurs when an electrical current is passed through a material and the material's resistivity causes heat generation.
Joule heating effects are common in electronic devices where the heat generated by a current may be an important influence.
Joule heating effects can be simulated by linking the results of an electrostatic analysis to a steady-state or transient heat transfer analysis.
www.algor.com /products/analysis_types/thermal/joule_heating.asp   (168 words)

  
 ChemTeam: Joule on Mechanical Equiv. of Heat
After reducing the result to the capacity for heat of a pound of water, it appeared that for each degree of heat evolved by the friction of water a mechanical power equal to that which can raise a weight of 890 lb.
I may therefore conclude that the existence of an equivalent relation between heat and the ordinary froms of mechanical power is proved; and assume 817 lb., the mean of the results of three distinct classes of experiments, as the equivalent, until more accurate experiments shall have been made.
Admitting the correctness of the equivalent I have named, it is obvious that the vis viva of the particles of a pound water at (say) 51° is equal to the vis viva possessed by a pound of water at 50° plus the vis viva which would be acquired by a weight of 817 lb.
dbhs.wvusd.k12.ca.us /webdocs/Chem-History/Joule-Heat-1845.html   (941 words)

  
 The Response and the Time Lags in the Neutral Thermosphere from Magnetospheric Forcing during the November 1993 Storm
Therefore the SH Joule heating compared to the NH in the TIEGCM with winds is 8% lower in general and 13% lower on Nov 4 as seen in Figure 1g.
The TIEGCM Joule heating was then multiplied by a correction fac- tor to account for variability in the E field that is largest in winter and increases the temperature, but does not affect the momentum transfer.
The westward shift of the zonal winds is the consequence of high latitude heating during magnetic storms, and is associated with the disturbance dynamo.
www-ssc.igpp.ucla.edu /gem/poster/emery   (2345 words)

  
 How to Couple Electrostatic and Heat Transfer Analyses for Joule Heating
The ability to predict how electrical current will affect temperature distribution is useful when analyzing spot welding, circuit breakers or other systems involving Joule heating, where materials heat up due to their resistance to a current passed through them.
For the spot welding model, a steady-state heat transfer analysis was specified with internal heat generation, convection and 100°C fixed nodal temperatures on the ends of the electrodes for loading.
The plates are heated until they begin to melt and flow together, forming a weld "nugget" at the intersection of the two plates.
www.algor.com /service_support/hints_tips/joule_heating.asp   (705 words)

  
 Joule Heating and the Conductivity Ellipsoid
Joule Heating: A greater Planck's constant will enable the universe to look further forward or back in time (the two are the same in this sense).
Joule Heating: The crux of it is that we will all mutate into stars.
Joule Heating: And as for me, I'll continue to be an expositor and leafleteer.
www.goatchurch.org.uk /fiction/Ellipsoid.html   (4601 words)

  
 Sowa. Results. Results of the simulations
A Chemistry Climate model is used to evaluate of the possible influence of Joule heating induced by the solar wind and interplanetary magnetic field (IMF) elements on the ozone concentration and dynamics of the Earth atmosphere.
The Joule heating rates in the stratosphere are parameterized on the base of the time series of the solar wind and IMF parameters taken from the NASA  database  (King,1999) for 1996.
The additional Joule heating leads to the significant increase of the temperature (about 1-2 K) in the SH stratosphere during the austral winter.
www.pmodwrc.ch /eugene1560/sowa/simul.phtml   (3877 words)

  
 Characterization of Joule heating in structured electric field environments
Since Joule heating is often regarded as an important mechanism contributing to energization of outflowing heavy ions observed by higher-altitude auroral satellites, this work has particular relevance to space physics issues, and, to our knowledge, has not been investigated systematically in a controlled environment.
Since transverse (to B) ionospheric electric fields are often spatially and temporally structured, with scale lengths often as small as an ion gyroradius, the ability to systematically vary the spatial extent and magnitude of an electric field region and to observe the effect on ion energy is important.
In addition, we show that measured heating is consistent with predictions of Joule heating as a function of ion-neutral collisions.
www.agu.org /pubs/crossref/2001/2000JA000181.shtml   (459 words)

  
 Frictional heating [Oulu]
Frictional heating is also very typical near auroral arcs that are related to electric field structures of their own.
Although the heating rates for neutrals and ions are very comparable, any increase in Tn should be far smaller than the corresponding increase in Ti due to the greater heat capacity of the neutral gas.
Different kind of frictional heating (and anisotropic ion temperatures) can be produced due to ion-ion collisions as the minor ion species with mass less than the mean ion mass are accelerated through the ion gas (Kelley, 1989, p.316).
www.oulu.fi /~spaceweb/textbook/friction.html   (955 words)

  
 HVAC Airconditioning and Heating - HVAC heating and Air Conditioning
The most commonly used setup is the central heating system where the heating is concentrated in one area—central—and is then circulated for various heating processes and applications.  Heat values of fuels are based on BTU to cubic foot measurement for HVAC.
A heat pump is very effective especially for very cold air since it has the ability to heat it at the shortest period.
In hydronic heating, heat produced is commonly transferred to fins found along pipes in baseboard HVAC registers.
www.hvachome.net /hvac/15/hvac-heating-and-air-conditioning   (738 words)

  
 Thermal Analysis of a Substrate with Power Dissipation in the Vias -- from Mathematica Information Center
This current flow results in Joule heating in the package, which must be included in any sizing of the package cooling requirements.
In this paper, we present an analysis of the temperature field resulting from the Joule heating in a metal wire surrounded by nonheat generating (electrically insulating) material.
Asymptotic solutions are given for arbitrarily temperature-dependent heat generation, when the insulating material thermal conductivity is much less than the thermal conductivity of the wire.
library.wolfram.com /infocenter/Articles/1683   (219 words)

  
 Resistivity : Resistance in toaster element   (Site not responding. Last check: 2007-10-16)
Resistance is the reason that the element heats up when the toaster is plugged in to an electric power supply.
The heating element in a toaster is typically a wire made of a mixture of metals (an alloy) such as nickel and chromium, which has a higher electrical resistance than a copper wire.
From the Joule heating equation, you can see that the heat (P) will be high when electrical resistance (R) is high.
www.seed.slb.com /qa2/FAQView.cfm?ID=972   (220 words)

  
 ANGEO - Abstracts
We investigate the Northern Hemisphere Joule heating from several observational and computational sources with the purpose of calibrating a previously identified functional dependence between solar wind parameters and ionospheric total energy consumption computed from a global magnetohydrodynamic (MHD) simulation (Grand Unified Magnetosphere Ionosphere Coupling Simulation, GUMICS-4).
Joule heating during a substorm is estimated from global observations, including electric fields provided by Super Dual Auroral Network (SuperDARN) and Pedersen conductances given by the ultraviolet (UV) and X-ray imagers on board the Polar satellite.
Furthermore, Joule heating is assessed from several activity index proxies, large statistical surveys, assimilative data methods (AMIE), and the global MHD simulation GUMICS-4.
www.copernicus.org /EGU/annales/23/6/2051.htm   (288 words)

  
 joule - a definition from Whatis.com   (Site not responding. Last check: 2007-10-16)
One joule is defined as the amount of energy exerted when a force of one newton is applied over a displacement of one meter.
One joule is the equivalent of one watt of power radiated or dissipated for one second.
One Btu is equivalent to approximately 1055 joules.
searchstorage.techtarget.com /definition/0,,sid5_gci213565,00.html   (146 words)

  
 US PATENT SUBCLASS 65 / 40-- .~.~ Dielectric or joule effect heating of work   (Site not responding. Last check: 2007-10-16)
The electrical energy must act directly on the work and not, for example, by convection or conduction of heat from an element not constituting a part of the work.
272+, for processes of adhesive bonding including heating by dielectric loss or by passing current through work which is capable of conducting an electrical current therethrough, and see the reference to other classes under "Search Class" in subclass 272 of Class 156 for related fields of search.
600+, for inductive heating, subclasses 678+ for microwave heating, and subclasses 764+ for capacitive dielectric heating.
www.patentec.com /data/class/defs/65/40.html   (169 words)

  
 2005_August_TechData   (Site not responding. Last check: 2007-10-16)
Maximum Joule heating is required for heaters, and their resistance is a good measure for the average temperature.
For minimal Joule heating ρ and L should be minimal and r maximal.
The second case concerns a lab experiment in which we want to limit the heat losses, for which the wire thermal resistance should be maximized and Joule heating minimized.
www.electronics-cooling.com /html/2005_august_techdata.html   (459 words)

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