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Topic: Phase change

	Phase (waves) - Wikipedia, the free encyclopedia
		The phase of a wave relates the position of a feature, typically a peak or a trough of the waveform, to that same feature in another part of the waveform (or, which amounts to the same, on a second waveform).
		The phase may be measured as a time, distance, a fraction of the wavelength, or as an angle.
		It is common to speak of inverting the polarity of a wave as "flipping the phase" or "shifting the phase by 180 degrees".
	en.wikipedia.org /wiki/Phase_(waves) (639 words)

	Phase transition - Wikipedia, the free encyclopedia
		The distinguishing characteristic of a phase transition is an abrupt sudden change in one or more physical properties, in particular the heat capacity, with a small change in a thermodynamic variable such as the temperature.
		The Ehrenfest scheme is an inaccurate method of classifying phase transitions, for it is based on the mean field theory of phases (to be described in a later section.) Mean field theory is inaccurate in the vicinity of phase transitions, as it neglects the role of thermodynamic fluctuations.
		Universality is a prediction of the renormalization group theory of phase transitions, which states that the thermodynamic properties of a system near a phase transition depend only on a small number of features, such as dimensionality and symmetry, and is insensitive to the underlying microscopic properties of the system.
	en.wikipedia.org /wiki/Phase_change (2039 words)

	Plasmon News - Phase Change Recording in 12-inch TrueWORM Technology & Trade
		The unrecorded phase change layer of a WORM disk is in the amorphous state.
		Phase Change alloys similar to those used for WORM media can also be used to produce a rewritable version; however, the unrecorded Phase Change layers of re-writable CD or DVD disks are transformed to the crystalline state during manufacture.
		Most phase change media, on the other hand, show remarkable resistance to corrosion with accelerated life tests, indicating that it will be hundreds of years before degradation of the recorded data is seen.
	www.plasmon.com /news/phase.html (1777 words)

	Phase Changes
		The data for the vaporization phase change presumes that the pressure is one standard atmosphere.
		In discussing the energy of the phase changes in water, we found that the potential energy is treated as a negative quantity.
		The change in the heat of vaporization can be roughly calculated using what we know from the specific heat of water, 1 calorie/gm °C. It takes 37 calories to heat a gram of water from 0°C to 37°C, but the change in the kinetic energy is much less than that:
	hyperphysics.phy-astr.gsu.edu /hbase/thermo/phase.html (747 words)

	Forcing a phase sequence change (Site not responding. Last check: 2007-10-21)
		2.9), if a change in phase sequence is requested during the final control cycle of a phase clock tick, the requested change in phase sequence is not recognized until the end of the following phase clock tick.
		So, the algorithm requesting a change in phase sequence should be written to handle the case that the control cycle within which a phase sequence change is requested will not necessarily be the last control cycle before the phase sequence change is actually made.
		If a control algorithm forces a change in phase sequence in order to recover from a problem with the discharge, it is possible that the problem will be resolved so that the algorithm will want to return control to the phase sequence that was in use just before the most recent phase sequence change.
	fusion.gat.com /pcs/master/node92.html (911 words)

	Phase Change (Site not responding. Last check: 2007-10-21)
		During a phase change, the kinetic energy (temperature) remains constant, while the potential energy increases or decreases.
		At moderate temperatures and high pressure, (liquid) water is the stable phase, and at high temperature and low pressure, (gas) vapor is the stable phase.
		Phase change for CO has some common features with that of water: sublimation curve, vaporization curve, triple point, critical temperature and pressure.
	www.tenafly.k12.nj.us /~shilfstein/links8.htm (911 words)

	untitled
		The term 'change of phase' means the same thing as the term 'change of state'.
		When a substance changes from one state, or phase, of matter to another we say that it has undergone a change of state, or we say that it has undergone a change of phase.
		In none of these changes of state is heat input used to speed up the molecules, nor is heat output ever occurring as a result of the molecules slowing down.
	id.mind.net /~zona/mstm/physics/mechanics/energy/heatAndTemperature/changesOfPhase/changeOfState.html (619 words)

	Temperature and Heat -- Change of Phase (Site not responding. Last check: 2007-10-21)
		However, there is an exception when the system is undergoing a change in phase -- for example, when ice melts into liquid water or liquid water turns into vapor.
		The molecules in a liquid are only slightly farther apart than they are in the solid phase, but this is enough to decrease the number of molecules that are stuck together; energy must be added to make this happen.
		Phase transitions going in the other direction (going from vapor to liquid or liquid to solid) result in a release of energy.
	www.pa.uky.edu /~straley/oldheat/heat/phase4.htm (499 words)

	Background on Optical Data (Site not responding. Last check: 2007-10-21)
		Phase change optical media uses the reflected light from amorphous and crystalline regions as information signals.
		Erasing the amorphous phase or creating a crystalline phase is done by heating the amorphous phase material above the glass transition temperature, but holding it below the melting point for enough time to allow the material to change into a crystalline state.
		The laser used for phase change optical media can be simple, because the polarization of light does not need to be preserved as does for magneto-optic media.
	engr.sjsu.edu /eallen/MATE152/CaseStudies/OpticalStorage/writing.htm (643 words)

	Genetic regulation of phase change in Arabidopsis.
		The transition from juvenile vegetative to adult vegetative development, a process known as phase change or shoot maturation, is marked by changes in morphology, anatomy, and physiology of the vegetative structures produced by the shoot.
		The duration of each phase directly impacts the morphology of plants because organs produced at different times are located at different positions along the shoot.
		Trichome distribution has a phase specific pattern in that leaves produced early in shoot development have trichomes only on their adaxial surface, while leaves produced later have trichomes on both the adaxial and abaxial surfaces.
	repository.upenn.edu /dissertations/AAI3003599 (360 words)

	Introduction to Phase Change Thermal Interface Materials (Site not responding. Last check: 2007-10-21)
		Phase change thermal interface materials can be handled as solid sheets at ambient temperature, but when the device heats up and the material temperature rises, the PCM changes from the solid sheet to a flowable compound.
		The phase change of the PCM from solid to a grease-like consistency allows the interface material to flow and fill in voids on the substrate surface.
		After the phase change, a PCM should behave essentially the same as a grease in minimizing interfacial resistance.
	www.coolingzone.com /Guest/News/NL_JUN_2003/Dow/Dow_Jun_2003.html (1081 words)

	Halfbakery: Phase Change Fever Blankets
		Lately, technology has offered up a solution: a paraffin-wax-like substance known as phase change material encapsulated in microscopic balls of heat-resistant plastic similar to that used in dishwasher-safe dinnerware.
		Phase change materials work because they are designed to maintain the midpoint of a narrow temperature range.
		One phase change material used in fleece jackets, for example, stays between about 27 °C and 38 °C when worn—or around 32 °C, which feels comfortable next to the skin.
	www.halfbakery.com /idea/Phase_20Change_20Fever_20Blankets (413 words)

	Phase Changes: Phase Diagram: Part 1 (Site not responding. Last check: 2007-10-21)
		A phase diagram is common way to represent the various phases of a substance and the conditions under which each phase exists.
		A phase diagram is a plot of pressure (P) vs temperature (T) in which lines on the diagram divide the plot into different regions.
		Although a substance has only one liquid and one gas phase, it is possible to have multiple solid phases corresponding with different arrangements and orientations of molecules in the crystal.
	www.chm.davidson.edu /ChemistryApplets/PhaseChanges/PhaseDiagram1.html (217 words)

	Phase Change Materials - Details (Site not responding. Last check: 2007-10-21)
		Phase change materials (PCMs), currently under research and development, can smooth daily fluctuations in room temperature by lowering the peak temperatures resulting from extreme external daily temperature changes.
		The resulting PCM, changes phases from solid to liquid at 82Â°F (28Â°C), at that point absorbing heat from a hot attic during the day, before it can penetrate into the home.
		A fundamental problem in the development of phase change storage is that some materials have a very narrow temperature range to change phases, or there is an ideal temperature that limits the material's use in climates where both heating and cooling are important.
	www.toolbase.org /docs/MainNav/Energy/2080_horizab1.html (556 words)

	Phase II change said to be working well
		Seniors who have not fulfilled Phase II by the spring term receive a letter from the Registrar stating that their names will not be placed on the degree list for graduation in June, he noted.
		Phase II is designed to demonstrate a student's competence in professional discourse within his or her own field.
		"[Phase II] is very, very important because it's one of the things students absolutely have to do to graduate," she said.
	www-tech.mit.edu /V109/N60/write.60n.html (676 words)

	zhaohui's research (Site not responding. Last check: 2007-10-21)
		Phase change recording materials are often called as Chalcogenide (compounds of elements in group VI, such as O, S, Se and Te).
		The parameters of crystallization kinetics are important for the simulation of phase change optical recording and also for the design of optical recording system.
		The storage mechanism is similar to the phase change optical recording, but here electric current is used to heat up the phase change material.
	www.contrib.andrew.cmu.edu /~zfan/research.html (679 words)

	Phase Change on Reflection (Site not responding. Last check: 2007-10-21)
		The net effect of the phase change is that the reflected ray ``jumps ahead" by half a wave length.
		If an even number of phase changes occur then the original, unmodified formulas must be used.
		The phase change does not happen when light is reflected off a less dense medium, i.e.
	theoryx5.uwinnipeg.ca /physics/light/node10.html (113 words)

	Phase Change Ink Jet
		Solid ink, consisting mainly of a transparent mixture of synthetic waxes, is used in phase change printers.
		One of the problems associated with phase change prints is that the image might be more susceptible to abrasion than a liquid ink print, but with a final step of cold pressure fusing the bond between the ink and the medium is greatly improved and the spherical droplet form is flattened out.
		In general, a continuous tone effect is not achieved with phase change printing.
	aic.stanford.edu /sg/emg/juergens/ID46.htm (382 words)

	Linux - Optical Disk HOWTO : Phase Change Optical Technology (Site not responding. Last check: 2007-10-21)
		Optical Phase Change technology is used to create "In Phase" or "Out of Phase" bits on a special media for phase change writing.
		What makes the phase change optical disk special is that it the disk is formatted with concentric cylinders or tracks with each track being sectored much like a magnetic disk or read/write optical disk.
		This means that it is not advisable to install a live operating system such as Linux on the phase change optical drive.
	sunsite.utk.edu /LDP/HOWTO/Optical-Disk-HOWTO-7.html (1465 words)

	Philips announce breakthrough in phase-change memory
		Phase-change materials, which change their physical properties depending on whether they are in their amorphous or crystalline phase, are widely used in optical storage media such as DVD Recordable and Rewritable discs.
		In these discs it is the reflectivity of the material that changes, with a laser being used both to heat the material to the required temperature in order to switch it between its amorphous and crystalline phases and to detect the resultant change in its reflectivity.
		In addition the phase changes occur extremely quickly, typically within 30 nanoseconds in Philips' prototype devices, with the added advantage that symmetrical programming pulses can be used.
	www.simmtester.com /page/news/shownews.asp?num=7888 (607 words)

	Changes of State (Site not responding. Last check: 2007-10-21)
		Once the water is in a liquid phase, increasing the amount of heat input raises the temperature of the liquid water
		In the region of the curve where we are not undergoing a phase transition, we are simply changing the temperature of one particular phase of water (either solid, liquid or gas) as a function of heat input
		In the regions of the curve where we are undergoing a phase transition, the heat energy input is not raising the temperature of the sample, rather it is being used to disrupt the intermolecular forces
	wine1.sb.fsu.edu /chm1045/notes/Forces/State/Forces04.htm (803 words)

	Preview
		Currently phase-change materials, which change their physical properties depending on whether they are in their amorphous or crystalline phase, are widely used in optical storage media such as DVD-Rewritable discs.
		While previous memory cells based on phase-change materials used a relatively high voltage to generate the heat needed to bring about the change from the amorphous phase to the crystalline phase, it is not practical to use such high voltages with silicon chips produced in advanced CMOS process technologies.
		According to Philips, the phase changes occurred within 30 ns in its prototype devices, which is 100 to 200 times faster than the time required to program a Flash memory cell, making its line-cell phase-change memory a viable replacement of DRAM in certain applications.
	www.techtree.com /techtree/jsp/showstory.jsp?storyid=66540 (724 words)

	Xtreme Resources Forum - TEC or Phase Change (Site not responding. Last check: 2007-10-21)
		Should i go with a TEC setup on a watercooled system, or a phase change like the vapo chill or prometeia stand alones.
		Phase change is more expensive, and TBH I don't think Vapos are very good, especially the cheaper ones.
		A TEC will (226W is really the only type you can compare to phase change) start off with nice low temps but they can't maintain the temps like a prom can.
	www.xtremeresources.com /forums/printthread.php?t=7919 (303 words)

	Phase Change (Site not responding. Last check: 2007-10-21)
		of a pure substance in the vapor phase appear as light green or purple balls.
		Select the relative magnitude (weak or strong) of the intermolecular forces of attraction in the liquid phase and temperature (T1,T2, or T3).
		The average numbers of molecules in the vapor and liquid phases, the vapor pressure, and the temperature are displayed above the reaction container.
	www.chm.davidson.edu /ronutt/che115/Phase/Phase.htm (247 words)

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