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Topic: Thermodynamic reversibility

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	Reversible process (thermodynamics) Summary
		In thermodynamics, a reversible process (or reversible cycle if the process is cyclic) is a process that can be "reversed" by means of infinitesimal changes in some property of the system.
		A reversible process changes the state of a system in such a way that the net change in the combined entropy of the system and its surroundings is zero.
		Reversible processes define the boundaries of how efficient heat engines can be in thermodynamics and engineering: a reversible process is one where no heat is lost from the system as "waste", and the machine is thus as efficient as it can possibly be (see Carnot cycle).
	www.bookrags.com /Reversible_process_(thermodynamics) (1105 words)

	Reversible process - Wikipedia, the free encyclopedia
		In thermodynamics, a reversible process (or reversible cycle if the process is cyclic) is a process that can be "reversed" by means of infinitesimal changes in some property of the system (Sears and Salinger, 1986).
		A reversible process changes the state of a system in such a way that the net change in the combined entropy of the system and its surroundings is zero.
		Reversible processes define the boundaries of how efficient heat engines can be in thermodynamics and engineering: a reversible process is one where no heat is lost from the system as "waste", and the machine is thus as efficient as it can possibly be (see Carnot cycle).
	en.wikipedia.org /wiki/Thermodynamic_reversibility (350 words)

	Sample Chapter for Haddad, W.M., Chellaboina, V., Nersesov, S.G.: Thermodynamics: A Dynamical Systems Approach. (Site not responding. Last check: 2007-11-05)
		Thermodynamics is a physical branch of science that deals with laws governing energy flow from one body to another and energy transformations from one form to another.
		Thermodynamics based on statistical mechanics is known as statistical thermodynamics and involves the mechanics of an ensemble of many particles (atoms or molecules) wherein the detailed description of the system state loses importance and only average properties of large numbers of particles are considered.
		Thermodynamics was spawned from the desire to design and build effcient heat engines, and it quickly spread to speculations about the universe upon the discovery of entropy as a fundamental physical property of matter.
	press.princeton.edu /chapters/s8122.html (5157 words)

	Irreversibility and Equilibrium in Biological Systems (Site not responding. Last check: 2007-11-05)
		This is the meaning of death, and it obeys to the law of thermodynamics that says that all systems in the universe have a tendency to the equilibrium (entropy).
		When a thermodynamic system delays, not stops nor reverts, the increase in its local entropy, it makes that the entropy of the environment, and soon the global entropy, increases by the same magnitude in which it would increase in that thermodynamic system.
		What Gibbs did not take into account is that some thermodynamic systems can delay the dispersion or diffusion of their energy towards more available microstates, that is, by limiting the number of available final microstates towards which the free energy or internal energy of the thermodynamic systems can be diffused or dispersed.
	www.biocab.org /Irreversibility.html (5557 words)

	Logical reversibility
		Reversibility, when one is referring to a computing device, is essentially the carrying out of a computation so that, at each step, it is possible to choose whether to execute that step or “undo” it, thus forcing the device and its environment to return to the conditions prior to execution.
		Reversibility and conservativity are two independent properties: However, although conservativity is a property satisfied by many physical systems, we do not consider it here, since it does not seem to pertain to the present work.
		A physically reversible device is a system whose behavior is governed by the reversible law of physics: for example a quantum computer [17] or the billiard-ball computer [5].
	www.research.ibm.com /journal/rd/456/zuliani.html (4790 words)

	THEORY OF RADIATION - LoveToKnow Article on THEORY OF RADIATION (Site not responding. Last check: 2007-11-05)
		so far reversible; but when it has arrived there, the molecules of the source will have changed their positions, and it cannot be wholly reabsorbed in the same manner as it was emitted.
		The thermodynamic compensation in such cases lies in the reduction of the effective temperature of the portion of the radiation not thus used up.
		On the other hand, the general reversing gaseous layer which originates the dark Fraunhofer lines is at a lower temperature than the radiating layer; it is only when the light from the lower layers is eclipsed that its own.
	www.1911encyclopedia.org /R/RA/RADIATION_THEORY_OF.htm (7134 words)

	THEORY OF RADIATION - Online Information article about THEORY OF RADIATION
		angle c, the tangential electric force is annulled at the reflector; hence the amplitude of the electric vibration is conserved on reflexion, though its phase is reversed.
		The thermodynamic compensation in such and Kurlbaum soon afterwards widely extended the test of the cases lies in the reduction of the effective temperature of the portion of the radiation not thus used up.
		By an argument based on the theory of dimensions, Lorentz has been led to the conclusion that consistency between temperatures, as measured molecularly, and as measured by the laws of radiation, requires that the ultimate indivisible electric charges or electrons must be the same in all kinds of matter.
	encyclopedia.jrank.org /PYR_RAY/RADIATION_THEORY_OF.html (9227 words)

	Alexander Kalina Steam Cycle --- Part 2 --- 15 patents
		It is absolutely clear, from a thermodynamic point of view, that unless the temperature of the heat acquisition by the working fluid is increased drastically, the efficiency of the process of conversion of thermal energy into power, i.e., the efficiency of the thermodynamic cycle, cannot be increased.
		Unlike a conventional thermodynamic cycle, the cycle of the present invention withdraws part of the gaseous working stream, after it has been partially expanded, to provide heat for a composite stream comprising that withdrawn part of the gaseous working stream together with a lower temperature lean stream.
		In the above described thermodynamic cycles of the present invention, all of the heating and evaporating of the liquid working stream may be provided in a recuperative way, i.e., the returning composite and spent streams transfer heat to the liquid working stream as these two streams cool.
	www.rexresearch.com /kalina/kalina2.htm (17031 words)

	Thermodynamics
		Thermodynamics and combustion chemistry (chemical reaction kinetics and equilibrium) combine to provide the theory required to calculate performance behavior of engine designs and to analyze rocket test data.
		Thermodynamics is the branch of physics involving heat and its conversion to other forms of energy and to work.
		The area under the reversible curve for an irreversible process does not represent heat or work because, depending on the extent of irreversibility, heat or work varies from the reversible value (the area under the curve) to zero for a completely irreversible process.
	www.innovatia.com /Design_Center/rktprop1.htm (2606 words)

	[No title]
		By the 1870s, it was already becoming clear that thermodynamic phenomena were a manifestation of the mechanical behavior of the microscopic constituents of matter.
		The idea of reversal of motions also occurred to Boltzmann's Viennese colleague, Franz Loschmidt, and it is by this route that the so-called "reversibility paradox" came to Boltzmann's attention.
		From this reversed perspective, in other words, the real work of explaining why entropy shows a universal tendency to decrease is done by an account of why it is low at a certain point in the future, together with the remark that the past is not similarly in need of explanation.
	www.usyd.edu.au /time/price/preprints/ISST.html (3508 words)

	20th WCP: Arrow of Time: Towards a New Epistemology of Science
		The reversible events are those which occur regularly and repeatedly, the cycles of seasons, harvesting, pendulum swinging in a frictionless medium, the motion of earth and the moon, are some of the examples.
		A process is said to be reversible if and only if the system which undergoes that process together with all parts of its environment which are affected, can be restored reproducibly to their original states.
		A world in which events occurred in the reverse order can be imagined, but a reversal to our sense of before -and- after would imply a state of mind in which we began with maximum information of the occurrence of events and ended with minimum, and this is selfcontradictory.
	www.bu.edu /wcp/Papers/TKno/TKnoAlte.htm (2973 words)

	ipedia.com: Thermodynamic reversibility Article (Site not responding. Last check: 2007-11-05)
		In thermodynamics a reversible process is a process in which the energy accumulated in the surroundings is exactly the same as the energy expended by the process with no losses due to friction or othe...
		In thermodynamics a reversible process is a process in which the energy accumulated in the surroundings is exactly the same as the energy expended by the process with no losses due to friction or other effects.
		A reversible process can be reversed at any point in the process by making a series of infinitesimal changes in the opposite direction of the original process.
	www.ipedia.com /thermodynamic_reversibility.html (307 words)

	Chemical reaction -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-11-05)
		This is referred to as ΔH, where Δ (Delta) means difference, and H stands for ((thermodynamics) a thermodynamic quantity equal to the internal energy of a system plus the product of its volume and pressure) enthalpy, a measure of energy which is equal to the heat transferred at constant pressure.
		The (A magnitude or frequency relative to a time unit) rate of a chemical reaction is a measure of how (The strength of a solution; number of molecules of a substance in a given volume (expressed as moles/cubic meter)) concentration of the involved substances changes with time.
		Analysis of reaction rates is important for several appliations, such as in (The activity of applying chemistry to the solution of practical problems) chemical engineering or in (A chemical reaction and its reverse proceed at equal rates) chemical equilibrium study.
	www.absoluteastronomy.com /encyclopedia/c/ch/chemical_reaction.htm (1430 words)

	Energy of Seawater Desalination
		Thermodynamic principles state that any method of water desalination will be most efficient, if it involves a reversible thermodynamic process.
		The same energy is invested in any reversible desalination process, and it is independent of the detailed technology employed, exact mechanism, or number of process stages.
		The process is reversible since the direction of the partition movement, and therefore, also of the water flow through the membrane, can be reversed at any given moment.
	urila.tripod.com /desalination.htm (723 words)

	Notes on the History of Reversible = Computation (Site not responding. Last check: 2007-11-05)
		For example, I wrote a reversible = program that=20 used repeated subtraction to test whether one integer is divisible by = another.=20 Such experiments revealed a common pattern: The computation consisted of = two=20 halves, the second of which almost exactly undid the work of the first.
		A proof of the thermodynamic reversibility of computation requires = not only=20 showing that logically irreversible operations can be avoided, but also = showing=20 that, once the computation has been rendered into the logically = reversible=20 format, some actual hardware.
		Such reversible nondemolition measurement schemes in = general exist=20 for classical systems, and for quantum systems in which the goal of the=20 measurement is to distinguish among orthogonal states of the system, = since these=20 states may in principle be made eigenstates of an appropriate = observable.
	www.cs.princeton.edu /courses/archive/fall04/cos576/papers/bennett88.mht (4695 words)

	Environmental Systems Research Program - Interfacial Processes Controlling Fate and Mobility of Actinides, Fission ...
		While the assumption of thermodynamic equilibrium may be valid for many reactions in relatively quiescent and chemically static systems, there is no guarantee that it is true in fast flow systems or in systems characterized by strong chemical gradients.
		Even in "simple" aquifer systems reaction reversibility is a relative unknown, yet this parameter will have a direct impact on source terms for aquifer contamination.
		The correlation of speciation with equilibria and reversibility will enable mobility results and causes at the bench scale to be directly compared with larger scale observations.
	www.inel.gov /esra/02portfolio/actinides.shtml (427 words)

	ESF Network for Philosophical and Foundational Problems of Modern Physics
		We present a thermodynamical analogy in entanglement theory, where mixed state entanglement is related to heat, and distillation of entanglement to drawing work by a heat engine.
		We argue that in any reversible theory this monotonicity is the only limitation for the asymptotic conversion rate from one state to another.
		The essence of the second law of classical thermodynamics is the ‘entropy principle’ which asserts the existence of an additive and extensive entropy function, S, that is defined for all equilibrium states of a thermodynamic system and whose increase characterizes the possible state changes under adiabatic conditions.
	www.philphys.nl /conferencesutrecht.html (3210 words)

	Basic Engineering Thermodynamics, 5th edition
		Engineering thermodynamics is the study of and practical application of the successful conversion of heat energy into work energy, a transformation fundamental to the existence of our modern industrial society.
		The thermodynamic conversion process lies behind the operation of the internal combustion engine and the generation of power.
		Basic Engineering Thermodynamics, first published in 1960, provides a comprehensive introduction to the principles and application of the subject.
	transatlanticpub.com /cat/tech/basi6291.htm (193 words)

	Helical logic
		The authors emphasize that other proposals for single electron thermodynamically reversible logic devices will certainly be advanced, so the present proposal must be viewed as the first in a class rather than "the" one and only design for a single electron thermodynamically reversible logic device.
		The reverse of this operation, in which three incoming helical paths produce two outgoing helical paths, is similar but "run backwards" in time.
		Note that in reverse operation it is essential that the presence or absence of a charge carrier on the data path be correctly correlated with the path (left or right) along which the switched charge is entering the switch gate.
	nano.xerox.com /nanotech/helical/deleteMe/back2 (11068 words)

	Protein Folding
		of the heteropolymer is thermodynamically stable and, accordingly, the global minimum of the free energy landscape.
		The observation of thermodynamic reversibility implied that proteins seek out the global minimum along a path directed as much by thermal fluctuations as by the local gradient.
		The essential impediment to accepting the thermodynamic view is the exponential size of the conformational landscape which the protein must explore.
	www.tcm.phy.cam.ac.uk /~tmf20/PHYSICS/thesis/node12.html (602 words)

	New Journal of Chemistry Articles (Site not responding. Last check: 2007-11-05)
		A variety of porphyrin-stoppered rotaxanes has been assembled under conditions of thermodynamic reversibility by judicious choice of components and temperatures.
		An admixture of a thread unit comprising a central naphthodiimide with terminal pyridines (2a), a ring unit dinaphtho-38-crown-10 (1) and either Zn 3a), Ru 3b) or Rh 3c) as stoppers was shown to form an equilibrating mixture of pseudorotaxanes and the porphyrin-stoppered rotaxanes.
		Nevertheless, although the thermodynamic stability of the overall rotaxane is expected to be comparable to that of the pseudorotaxane, there is clearly an enhanced kinetic barrier for formation of the metalloporphyrin-stoppered rotaxanes, but not for the more labile zinc analogue.
	www.rsc.org /Publishing/Journals/NJ/article.asp?DOI=b006911f (324 words)

	Articles - Nicolas LÃ©onard Sadi Carnot (Site not responding. Last check: 2007-11-05)
		Perhaps the most important contribution Carnot made to thermodynamics was the process of abstraction of the essential features of the steam engine as it was known in his day into a more general, idealized heat engine.
		In his ideal model, the head of caloric converted into work could be reinstated by reversing the motion of the cycle, a concept subsequently known as thermodynamic reversibility.
		It has been remarked, in fact, that "the development of thermodynamics owes more to the steam engine, than the development of the steam engine owes to thermodynamics." The practical developments, as is so often the case in science, led the way.
	www.refice.com /articles/Nicolas_L%c3%a9onard_Sadi_Carnot (1139 words)

	Reversible Electronic Logic Using Switches
		In a reversible system of the type described here the voltage V would be the error in the voltage of the power supply, rather than the voltage of the power supply itself.
		Thus, by using reversible instead of irreversible logic, we have effectively reduced the value of V. With a power supply accurate to 5%, the energy losses from charging and discharging the load capacitances associated with the electrical connections would be decreased by a factor of 20^2 or 400.
		A reversible method of refreshing a packet would be to use the old packet to charge a bucket in a reversible fashion (as discussed in the first method), and then to "unwrite" or discharge the bucket holding the old packet by using the new packet as the source of information.
	www.zyvex.com /nanotech/electroTextOnly.html (15594 words)

	Helical logic
		The authors emphasize that other proposals for single electron thermodynamically reversible logic devices will certainly be advanced, so the present proposal must be viewed as the first in a class rather than "the" one and only design for a single electron thermodynamically reversible logic device.
		The reverse of this operation, in which three incoming helical paths produce two outgoing helical paths, is similar but "run backwards" in time.
		Note that in reverse operation it is essential that the presence or absence of a charge carrier on the data path be correctly correlated with the path (left or right) along which the switched charge is entering the switch gate.
	www.zyvex.com /nanotech/helical/helical.html (10978 words)

	BioMed Central \| Full text \| Systematic assignment of thermodynamic constraints in metabolic network models
		A thermodynamically infeasible operation of a subnetwork is, for example, given by a cyclic operation of a reaction set that in total results in no net conversion of metabolites.
		On the contrary, the reverse operation of this reaction cycle is thermodynamically infeasible as the "motor" would then operate in opposite direction and would become a "generator": The cycle would produce energy (e.g.
		After having exploited all available thermodynamic data to define irreversible reactions, we drew on network topology and thermodynamic heuristics to assign further reaction directions: Energy producing cycles were extracted from the reaction network and thermodynamically infeasible reaction steps that produce high-energy from low-energy co-substrates were disabled.
	www.biomedcentral.com /1471-2105/7/512 (6694 words)

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