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Exergy

Exergy, often referred to as "available energy" or "useful work potential", is a fundamental concept in the field of thermodynamics and engineering. It plays a crucial role in understanding and quantifying the quality of energy within a system and its potential to perform useful work. Exergy analysis has widespread applications in various fields, including energy engineering, environmental science, and industrial processes.

From a scientific and engineering perspective, second-law-based exergy analysis is valuable because it provides a number of benefits over energy analysis alone. These benefits include the basis for determining energy quality (or exergy content  ), enhancing the understanding of fundamental physical phenomena, and improving design, performance evaluation and optimization efforts. In thermodynamics, the exergy of a system is the maximum useful work that can be produced as the system is brought into equilibrium with its environment by an ideal process. The specification of an "ideal process" allows the determination of "maximum work" production. From a conceptual perspective, exergy is the "ideal" potential of a system to do work or cause a change as it achieves equilibrium with its environment. Exergy is also known as "availability". Exergy is non-zero when there is dis-equilibrium between the system and its environment, and exergy is zero when equilibrium is established (the state of maximum entropy for the system plus its environment).

Determining exergy was one of the original goals of thermodynamics. The term "exergy" was coined in 1956 by Zoran Rant (1904–1972) by using the Greek ex and ergon, meaning "from work", but the concept had been earlier developed by J. Willard Gibbs (the namesake of Gibbs free energy) in 1873.

Energy is neither created nor destroyed, but is simply converted from one form to another (see First law of thermodynamics). In contrast to energy, exergy is always destroyed when a process is non-ideal or irreversible (see Second law of thermodynamics). To illustrate, when someone states that "I used a lot of energy running up that hill", the statement contradicts the first law. Although the energy is not consumed, intuitively we perceive that something is. The key point is that energy has quality or measures of usefulness, and this energy quality (or exergy content) is what is consumed or destroyed. This occurs because everything, all real processes, produce entropy and the destruction of exergy or the rate of "irreversibility" is proportional to this entropy production (Gouy–Stodola theorem). Where entropy production may be calculated as the net increase in entropy of the system together with its surroundings. Entropy production is due to things such as friction, heat transfer across a finite temperature difference and mixing. In distinction from "exergy destruction", "exergy loss" is the transfer of exergy across the boundaries of a system, such as with mass or heat loss, where the exergy flow or transfer is potentially recoverable. The energy quality or exergy content of these mass and energy losses are low in many situations or applications, where exergy content is defined as the ratio of exergy to energy on a percentage basis. For example, while the exergy content of electrical work produced by a thermal power plant is 100%, the exergy content of low-grade heat rejected by the power plant, at say, 41 degrees Celsius, relative to an environment temperature of 25 degrees Celsius, is only 5%.

Definitions
Exergy is a combination property of a system and its environment because it depends on the state of both and is a consequence of dis-equilibrium between them. Exergy is neither a thermodynamic property of matter nor a thermodynamic potential of a system. Exergy and energy always have the same units, and the joule (symbol: J) is the unit of energy in the International System of Units (SI). The internal energy of a system is always measured from a fixed reference state and is therefore always a state function. Some authors define the exergy of the system to be changed when the environment changes, in which case it is not a state function. Other writers prefer a slightly alternate definition of the available energy or exergy of a system where the environment is firmly defined, as an unchangeable absolute reference state, and in this alternate definition, exergy becomes a property of the state of the system alone.

However, from a theoretical point of view, exergy may be defined without reference to any environment. If the intensive properties of different finitely extended elements of a system differ, there is always the possibility to extract mechanical work from the system. Yet, with such an approach one has to abandon the requirement that the environment is large enough relative to the "system" such that its intensive properties, such as temperature, are unchanged due to its interaction with the system. So that exergy is defined in an absolute sense, it will be assumed in this article that, unless otherwise stated, that the environment's intensive properties are unchanged by its interaction with the system.

For a heat engine, the exergy can be simply defined in an absolute sense, as the energy input times the Carnot efficiency, assuming the low-temperature heat reservoir is at the temperature of the environment. Since many systems can be modeled as a heat engine, this definition can be useful for many applications.

Terminology
The term exergy is also used, by analogy with its physical definition, in information theory related to reversible computing. Exergy is also synonymous with available energy, exergic energy, essergy (considered archaic), utilizable energy, available useful work, maximum (or minimum) work, maximum (or minimum) work content, reversible work, ideal work, availability or available work.

Implications
The exergy destruction of a cycle is the sum of the exergy destruction of the processes that compose that cycle. The exergy destruction of a cycle can also be determined without tracing the individual processes by considering the entire cycle as a single process and using one of the exergy destruction equations.

Examples
For two thermal reservoirs at temperatures TH and TC < TH, as considered by Carnot, the exergy is the work W that can be done by a reversible engine. Specifically, with QH the heat provided by the hot reservoir, Carnot's analysis gives W/QH = (TH − TC)/TH. Although, exergy or maximum work is determined by conceptually utilizing an ideal process, it is the property of a system in a given environment. Exergy analysis is not merely for reversible cycles, but for all cycles (including non-cyclic or non-ideal), and indeed for all thermodynamic processes.

As an example, consider the non-cyclic process of expansion of an ideal gas. For free expansion in an isolated system, the energy and temperature do not change, so by energy conservation no work is done. On the other hand, for expansion done against a moveable wall that always matched the (varying) pressure of the expanding gas (so the wall develops negligible kinetic energy), with no heat transfer (adiabatic wall), the maximum work would be done. This corresponds to the exergy. Thus, in terms of exergy, Carnot considered the exergy for a cyclic process with two thermal reservoirs (fixed temperatures). Just as the work done depends on the process, so the exergy depends on the process, reducing to Carnot's result for Carnot's case.

W. Thomson (from 1892, Lord Kelvin), as early as 1849 was exercised by what he called “lost energy”, which appears to be the same as “destroyed energy” and what has been called “anergy”. In 1874 he wrote that “lost energy” is the same as the energy dissipated by, e.g., friction, electrical conduction (electric field-driven charge diffusion), heat conduction (temperature-driven thermal diffusion), viscous processes (transverse momentum diffusion) and particle diffusion (ink in water). On the other hand, Kelvin did not indicate how to compute the “lost energy”. This awaited the 1931 and 1932 works of Onsager on irreversible processes.

An application of the second law of thermodynamics
Exergy uses system boundaries in a way that is unfamiliar to many. We imagine the presence of a Carnot engine between the system and its reference environment even though this engine does not exist in the real world. Its only purpose is to measure the results of a "what-if" scenario to represent the most efficient work interaction possible between the system and its surroundings.

If a real-world reference environment is chosen that behaves like an unlimited reservoir that remains unaltered by the system, then Carnot's speculation about the consequences of a system heading towards equilibrium with time is addressed by two equivalent mathematical statements. Let B, the exergy or available work, decrease with time, and Stotal, the entropy of the system and its reference environment enclosed together in a larger isolated system, increase with time:

For macroscopic systems (above the thermodynamic limit), these statements are both expressions of the second law of thermodynamics if the following expression is used for exergy:

where the extensive quantities for the system are: U = Internal energy, V = Volume, and Ni = Moles of component i. The intensive quantities for the surroundings are: PR = Pressure, TR = temperature, μ i, R = Chemical potential of component i. Indeed the total entropy of the universe reads:

the second term $$ - U/T_R - P_R V /T_R + \sum_i \mu_{i,R} N_i /T_R $$ being the entropy of the surroundings to within a constant.

Individual terms also often have names attached to them: $$P_R V$$ is called "available PV work", $$T_R S$$ is called "entropic loss" or "heat loss" and the final term is called "available chemical energy."

Other thermodynamic potentials may be used to replace internal energy so long as proper care is taken in recognizing which natural variables correspond to which potential. For the recommended nomenclature of these potentials, see (Alberty, 2001). Equation ($$) is useful for processes where system volume, entropy, and the number of moles of various components change because internal energy is also a function of these variables and no others.

An alternative definition of internal energy does not separate available chemical potential from U. This expression is useful (when substituted into equation ($$)) for processes where system volume and entropy change, but no chemical reaction occurs:

In this case, a given set of chemicals at a given entropy and volume will have a single numerical value for this thermodynamic potential. A multi-state system may complicate or simplify the problem because the Gibbs phase rule predicts that intensive quantities will no longer be completely independent from each other.

A historical and cultural tangent
In 1848, William Thomson, 1st Baron Kelvin, asked (and immediately answered) the question

 * Is there any principle on which an absolute thermometric scale can be founded? It appears to me that Carnot's theory of the motive power of heat enables us to give an affirmative answer.

With the benefit of the hindsight contained in equation ($$), we are able to understand the historical impact of Kelvin's idea on physics. Kelvin suggested that the best temperature scale would describe a constant ability for a unit of temperature in the surroundings to alter the available work from Carnot's engine. From equation ($$):

Rudolf Clausius recognized the presence of a proportionality constant in Kelvin's analysis and gave it the name entropy in 1865 from the Greek for "transformation" because it quantifies the amount of energy lost during the conversion from heat to work. The available work from a Carnot engine is at its maximum when the surroundings are at a temperature of absolute zero.

Physicists then, as now, often look at a property with the word "available" or "utilizable" in its name with a certain unease. The idea of what is available raises the question of "available to what?" and raises a concern about whether such a property is anthropocentric. Laws derived using such a property may not describe the universe but instead, describe what people wish to see.

The field of statistical mechanics (beginning with the work of Ludwig Boltzmann in developing the Boltzmann equation) relieved many physicists of this concern. From this discipline, we now know that macroscopic properties may all be determined from properties on a microscopic scale where entropy is more "real" than temperature itself (see Thermodynamic temperature). Microscopic kinetic fluctuations among particles cause entropic loss, and this energy is unavailable for work because these fluctuations occur randomly in all directions. The anthropocentric act is taken, in the eyes of some physicists and engineers today, when someone draws a hypothetical boundary, in fact, he says: "This is my system. What occurs beyond it is surroundings." In this context, exergy is sometimes described as an anthropocentric property, both by some who use it and by some who don't. However, exergy is based on the dis-equilibrium between a system and its environment, so its very real and necessary to define the system distinctly from its environment. It can be agreed that entropy is generally viewed as a more fundamental property of matter than exergy.

A potential for every thermodynamic situation
In addition to $$U $$ and $ U[\boldsymbol{\mu}]$, the other thermodynamic potentials are frequently used to determine exergy. For a given set of chemicals at a given entropy and pressure, enthalpy H is used in the expression:

For a given set of chemicals at a given temperature and volume, Helmholtz free energy A is used in the expression:

For a given set of chemicals at a given temperature and pressure, Gibbs free energy G is used in the expression:

where $$G$$ is evaluated at the isothermal system temperature ($$T$$), and $$B$$ is defined with respect to the isothermal temperature of the system's environment ($$T_R$$). The exergy $$B$$ is the energy $$H$$ reduced by the product of the entropy times the environment temperature $$T_R$$, which is the slope or partial derivative of the internal energy with respect to entropy in the environment. That is, higher entropy reduces the exergy or free energy available relative to the energy level $$H$$.

Work can be produced from this energy, such as in an isothermal process, but any entropy generation during the process will cause the destruction of exergy (irreversibility) and the reduction of these thermodynamic potentials. Further, exergy losses can occur if mass and energy is transferred out of the system at non-ambient or elevated temperature, pressure or chemical potential. Exergy losses are potentially recoverable though because the exergy has not been destroyed, such as what occurs in waste heat recovery systems (although the energy quality or exergy content is typically low). As a special case, an isothermal process operating at ambient temperature will have no thermally related exergy losses.

Exergy Analysis involving Radiative Heat Transfer
All matter emits radiation continuously as a result of its non-zero (absolute) temperature. This emitted energy flow is proportional to the material’s temperature raised to the fourth power. As a result, any radiation conversion device that seeks to absorb and convert radiation (while reflecting a fraction of the incoming source radiation) inherently emits its own radiation. Also, given that reflected and emitted radiation can occupy the same direction or solid angle, the entropy flows, and as a result, the exergy flows, are generally not independent. The entropy and exergy balance equations for a control volume (CV), re-stated to correctly apply to situations involving radiative transfer, are expressed as,

$$ \frac {dS_{CV}}{dt} = \int_{CV boundary} (\frac{q_{cc}}{T_b} + J_{NetRad})dA+\sum_{i}^m({\dot{m}_i}s_i)-\sum_{o}^n({\dot{m}_o}s_o)+\dot{S}_{gen}$$ where $${S}_{gen}$$ or $Π$ denotes entropy production within the control volume, and,

$$ \frac {{dX}_{CV}}{dt} = \int_{CV boundary}[{q_{cc}}(1-\frac{T_o}{T_b}) + M_{NetRad}]dA-({\dot{W}_{CV}}-P_o(\frac{dV_{CV}}{dt}))+\sum_{i}^r({\dot{m}_i}(h_i-{T_o}{s_i}))-\dot{I}_{CV}$$

This rate equation for the exergy within an open system X ($Ξ or B$) takes into account the exergy transfer rates across the system boundary by heat transfer ($q$ for conduction & convection, and $M$ by radiative fluxes), by mechanical or electrical work transfer ($W$), and by mass transfer ($m$), as well as taking into account the exergy destruction ($I$) that occurs within the system due to irreversibility’s or non-ideal processes. Note that chemical exergy, kinetic energy, and gravitational potential energy have been excluded for simplicity.

The exergy irradiance or flux M, and the exergy radiance N (where M = πN for isotropic radiation), depend on the spectral and directional distribution of the radiation (for example, see the next section on ‘Exergy Flux of Radiation with an Arbitrary Spectrum’). Sunlight can be crudely approximated as blackbody, or more accurately, as graybody radiation. Noting that, although a graybody spectrum looks similar to a blackbody spectrum, the entropy and exergy are very different. Petela determined that the exergy of isotropic blackbody radiation was given by the expression,

$$M_{BR} = \frac{cX}{4V} = \sigma T^4 (1-\frac{4}{3}x+\frac{1}{3}x^4)$$

where the exergy within the enclosed system is X ($Ξ or B$), c is the speed of light, V is the volume occupied by the enclosed radiation system or void, T is the material emission temperature, To is the environmental temperature, and x is the dimensionless temperature ratio To/T.

However, for decades this result was contested in terms of its relevance to the conversion of radiation fluxes, and in particular, solar radiation. For example, Bejan stated that “Petela’s efficiency is no more than a convenient, albeit artificial way, of non-dimensionalizing the calculated work output” and that Petela’s efficiency “is not a ‘conversion efficiency.’ ” However, it has been shown that Petela’s result represents the exergy of blackbody radiation. This was done by resolving a number of issues, including that of inherent irreversibility, defining the environment in terms of radiation, the effect of inherent emission by the conversion device and the effect of concentrating source radiation.

Exergy Flux of Radiation with an Arbitrary Spectrum (including Sunlight)
In general, terrestrial solar radiation has an arbitrary non-blackbody spectrum. Ground level spectrums can vary greatly due to reflection, scattering and absorption in the atmosphere. While the emission spectrums of thermal radiation in engineering systems can vary widely as well.

In determining the exergy of radiation with an arbitrary spectrum, it must be considered whether reversible or ideal conversion (zero entropy production) is possible. It has been shown that reversible conversion of blackbody radiation fluxes across an infinitesimal temperature difference is theoretically possible ]. However, this reversible conversion can only be theoretically achieved because equilibrium can exist between blackbody radiation and matter. However, non-blackbody radiation cannot even exist in equilibrium with itself, nor with its own emitting material.

Unlike blackbody radiation, non-blackbody radiation cannot exist in equilibrium with matter, so it appears likely that the interaction of non-blackbody radiation with matter is always an inherently irreversible process. For example, an enclosed non-blackbody radiation system (such as a void inside a solid mass) is unstable and will spontaneously equilibriate to blackbody radiation unless the enclosure is perfectly reflecting (i.e., unless there is no thermal interaction of the radiation with its enclosure – which is not possible in actual, or real, non-ideal systems). Consequently, a cavity initially devoid of thermal radiation inside a non-blackbody material will spontaneously and rapidly (due to the high velocity of the radiation), through a series of absorption and emission interactions, become filled with blackbody radiation rather than non-blackbody radiation.

The approaches by Petela and Karlsson both assume that reversible conversion of non-blackbody radiation is theoretically possible, that is, without addressing or considering the issue. Exergy is not a property of the system alone, it’s a property of both the system and its environment. Thus, it is of key importance non-blackbody radiation cannot exist in equilibrium with matter, indicating that the interaction of non-blackbody radiation with matter is an inherently irreversible process.

The flux (irradiance) of radiation with an arbitrary spectrum, based on the inherent irreversibility of non-blackbody radiation conversion, is given by the expression,

$$M=H-T_o(\frac{4}{3}\sigma^{0.25} H^{0.75})+\frac{\sigma}{3}T_o^4)$$

The exergy flux $$M$$ is expressed as a function of only the energy flux or irradiance $$H$$ and the environment temperature $$T_o$$. For graybody radiation, the exergy flux is given by the expression,

$$M_{GR}=\sigma T^4 (\epsilon-\frac{4}{3}x\epsilon^{0.75}+\frac{1}{3}x^4)$$

As one would expect, the exergy flux of non-blackbody radiation reduces to the result for blackbody radiation when emissivity is equal to one.

Note that the exergy flux of graybody radiation can be a small fraction of the energy flux. For example, the ratio of exergy flux to energy flux $$(M/H)$$ for graybody radiation with emissivity $$\epsilon = 0.50$$ is equal to 40.0%, for $$T = 500^oC$$ and $$ T_o = 27^oC  (x = 0.388)$$. That is, a maximum of only 40% of the graybody energy flux can be converted to work in this case (already only 50% of that of the blackbody energy flux with the same emission temperature). Graybody radiation has a spectrum that looks similar to the blackbody spectrum, but the entropy and exergy flux cannot be accurately approximated as that of blackbody radiation with the same emission temperature. However, it can be reasonably approximated by the entropy flux of blackbody radiation with the same energy flux (lower emission temperature).

Blackbody radiation has the highest entropy-to-energy ratio of all radiation with the same energy flux, but the lowest entropy-to-energy ratio, and the highest exergy content, of all radiation with the same emission temperature. For example, the exergy content of graybody radiation is lower than that of blackbody radiation with the same emission temperature and decreases as emissivity decreases. For the example above with $$x = 0.388$$ the exergy flux of the blackbody radiation source flux is 52.5% of the energy flux compared to 40.0% for graybody radiation with $$\epsilon = 0.50$$, or compared to 15.5% for graybody radiation with $$\epsilon = 0.10$$.

The Exergy Flux of Sunlight
In addition to the production of power directly from sunlight, solar radiation provides most of the exergy for processes on Earth, including processes that sustain living systems directly, as well as all fuels and energy sources that are used for transportation and electric power production (directly or indirectly). This is primarily with the exception of nuclear fission power plants and geothermal energy (due to natural fission decay). Solar energy is, for the most part, thermal radiation from the Sun with an emission temperature near 5762 Kelvin, but it also includes small amounts of higher energy radiation from the fusion reaction or higher thermal emission temperatures within the Sun. The source of most energy on Earth is nuclear in origin.

The figure below depicts typical solar radiation spectrums under clear sky conditions for AM0 (extraterrestrial solar radiation), AM1 (terrestrial solar radiation with solar zenith angle of 0 degrees) and AM4 (terrestrial solar radiation with solar zenith angle of 75.5 degrees). The solar spectrum at sea level (terrestrial solar spectrum) depends on a number of factors including the position of the Sun in the sky, atmospheric turbidity, the level of local atmospheric pollution, and the amount and type of cloud cover. These spectrums are for relatively clear air (α = 1.3, β = 0.04) assuming a U.S. standard atmosphere with 20 mm of precipitable water vapor and 3.4 mm of ozone. The Figure shows the spectral energy irradiance (W/m2μm) which does not provide information regarding the directional distribution of the solar radiation. The exergy content of the solar radiation, assuming that it is subtended by the solid angle of the ball of the Sun (no circumsolar), is 93.1%, 92.3% and 90.8%, respectively, for the AM0, AM1 and the AM4 spectrums.

The exergy content of terrestrial solar radiation is also reduced because of the diffuse component caused by the complex interaction of solar radiation, originally in a very small solid angle beam, with material in the Earth’s atmosphere. The characteristics and magnitude of diffuse terrestrial solar radiation depends on a number of factors, as mentioned, including the position of the Sun in the sky, atmospheric turbidity, the level of local atmospheric pollution, and the amount and type of cloud cover. Solar radiation under clear sky conditions exhibits a maximum intensity towards the Sun (circumsolar radiation) but also exhibits an increase in intensity towards the horizon (horizon brightening). In contrast for opaque overcast skies the solar radiation can be completely diffuse with a maximum intensity in the direction of the zenith and monotonically decreasing towards the horizon. The magnitude of the diffuse component generally varies with frequency, being highest in the ultraviolet region.

The dependence of the exergy content on directional distribution can be illustrated by considering, for example, the AM1 and AM4 terrestrial spectrums depicted in the figure, with the following simplified cases of directional distribution:

•	For AM1: 80% of the solar radiation is contained in the solid angle subtended by the Sun, 10% is contained and isotropic in a solid angle 0.008 sr (this field of view includes circumsolar radiation), while the remaining 10% of the solar radiation is diffuse and isotropic in the solid angle 2π sr.

•	For AM4: 65% of the solar radiation is contained in the solid angle subtended by the Sun, 20% of the solar radiation is contained and isotropic in a solid angle 0.008 sr, while the remaining 15% of the solar radiation is diffuse and isotropic in the solid angle 2π sr. Note that when the Sun is low in the sky the diffuse component can be the dominant part of the incident solar radiation.

For these cases of directional distribution, the exergy content of the terrestrial solar radiation for the AM1 and AM4 spectrum depicted are 80.8% and 74.0%, respectively. From these sample calculations it is evideνnt that the exergy content of terrestrial solar radiation is strongly dependent on the directional distribution of the radiation. This result is interesting because one might expect that the performance of a conversion device would depend on the incoming rate of photons and their spectral distribution but not on the directional distribution of the incoming photons. However, for a given incoming flux of photons with a certain spectral distribution, the entropy (level of disorder) is higher the more diffuse the directional distribution. From the second law of thermodynamics, the incoming entropy of the solar radiation cannot be destroyed and consequently reduces the maximum work output that can be obtained by a conversion device.

Chemical exergy
Similar to thermomechanical exergy, chemical exergy depends on the temperature and pressure of a system as well as on the composition. The key difference in evaluating chemical exergy versus thermomechanical exergy is that thermomechanical exergy does not take into account the difference in a system and the environment's chemical composition. If the temperature, pressure or composition of a system differs from the environment's state, then the overall system will have exergy.

The definition of chemical exergy resembles the standard definition of thermomechanical exergy, but with a few differences. Chemical exergy is defined as the maximum work that can be obtained when the considered system is brought into reaction with reference substances present in the environment. Defining the exergy reference environment is one of the most vital parts of analyzing chemical exergy. In general, the environment is defined as the composition of air at 25 °C and 1 atm of pressure. At these properties air consists of N2=75.67%, O2=20.35%, H2O(g)=3.12%, CO2=0.03% and other gases=0.83%. These molar fractions will become of use when applying Equation 8 below.

CaHbOc is the substance that is entering a system that one wants to find the maximum theoretical work of. By using the following equations, one can calculate the chemical exergy of the substance in a given system. Below, Equation 9 uses the Gibbs function of the applicable element or compound to calculate the chemical exergy. Equation 10 is similar but uses standard molar chemical exergy, which scientists have determined based on several criteria, including the ambient temperature and pressure that a system is being analyzed and the concentration of the most common components. These values can be found in thermodynamic books or in online tables.

Important equations
where:
 * $$\bar{g}_{x}$$ is the Gibbs function of the specific substance in the system at $$\left( T_{0}, p_{0} \right)$$. ($$\bar{g}_{F}$$ refers to the substance that is entering the system)

 * $$\bar{R}$$ is the Universal gas constant (8.314462 J/mol•K)
 * $$T_{0}$$ is the temperature that the system is being evaluated at in absolute temperature
 * $$y_{x}^{e}$$ is the molar fraction of the given substance in the environment, i.e. air

where $$\bar{e}_{x}^{ch}$$ is the standard molar chemical exergy taken from a table for the specific conditions that the system is being evaluated.

Equation 10 is more commonly used due to the simplicity of only having to look up the standard chemical exergy for given substances. Using a standard table works well for most cases, even if the environmental conditions vary slightly, the difference is most likely negligible.

Total exergy
After finding the chemical exergy in a given system, one can find the total exergy by adding it to the thermomechanical exergy. Depending on the situation, the amount of chemical exergy added can be very small. If the system being evaluated involves combustion, the amount of chemical exergy is very large and necessary to find the total exergy of the system.

Irreversibility
Irreversibility accounts for the amount of exergy destroyed in a closed system, or in other words, the wasted work potential. This is also called dissipated energy. For highly efficient systems, the value of $I$, is low, and vice versa. The equation to calculate the irreversibility of a closed system, as it relates to the exergy of that system, is as follows:

where $$ S_\text{gen} $$, also denoted by $Π$, is the entropy generated by processes within the system. If $$I > 0$$ then there are irreversibilities present in the system. If $$I = 0$$ then there are no irreversibilities present in the system. The value of $I$, the irreversibility, can not be negative, as this implies entropy destruction, a direct violation of the second law of thermodynamics.

Exergy analysis also relates the actual work of a work producing device to the maximal work, that could be obtained in the reversible or ideal process:

That is, the irreversibility is the ideal maximum work output minus the actual work production. Whereas, for a work consuming device such as refrigeration or heat pump, irreversibility is the actual work input minus the ideal minimum work input.

The first term at the right part is related to the difference in exergy at inlet and outlet of the system:

where $B$ is also denoted by $Ξ or X$.

For an isolated system there are no heat or work interactions or transfers of exergy between the system and its surroundings. The exergy of an isolated system can therefore only decrease, by a magnitude equal to the irreversibility of that system or process,

Applications
Applying equation ($$) to a subsystem yields:

This expression applies equally well for theoretical ideals in a wide variety of applications: electrolysis (decrease in G), galvanic cells and fuel cells (increase in G), explosives (increase in A), heating and refrigeration (exchange of H), motors (decrease in U) and generators (increase in U).

Utilization of the exergy concept often requires careful consideration of the choice of reference environment because, as Carnot knew, unlimited reservoirs do not exist in the real world. A system may be maintained at a constant temperature to simulate an unlimited reservoir in the lab or in a factory, but those systems cannot then be isolated from a larger surrounding environment. However, with a proper choice of system boundaries, a reasonable constant reservoir can be imagined. A process sometimes must be compared to "the most realistic impossibility," and this invariably involves a certain amount of guesswork.

Engineering applications
One goal of energy and exergy methods in engineering is to compute what comes into and out of several possible designs before a design is built. Energy input and output will always balance according to the First Law of Thermodynamics or the energy conservation principle. Exergy output will not equal the exergy input for real processes since a part of the exergy input is always destroyed according to the Second Law of Thermodynamics for real processes. After the input and output are calculated, an engineer will often want to select the most efficient process. An energy efficiency or first law efficiency will determine the most efficient process based on wasting as little energy as possible relative to energy inputs. An exergy efficiency or second-law efficiency will determine the most efficient process based on wasting and destroying as little available work as possible from a given input of available work, per unit of whatever the desired output is.

Exergy has been applied in a number of design applications in order to optimize systems or identify components or subsystems with the greatest potential for improvement. For instance, an exergy analysis of environmental control systems on the international space station revealed the oxygen generation assembly as the subsystem which destroyed the most exergy.

Exergy is particularly useful for broad engineering analyses with many systems of varied nature, since it can account for mechanical, electrical, nuclear, chemical, or thermal systems. For this reason, Exergy analysis has also been used to optimize the performance of rocket vehicles. Exergy analysis affords additional insight, relative to energy analysis alone, because it incorporates the second law, and considers both the system and its relationship with its environment. For example, exergy analysis has been used to compare possible power generation and storage systems on the moon, since exergy analysis is conducted in reference to the unique environmental operating conditions of a specific application, such as on the surface of the moon.

Application of exergy to unit operations in chemical plants was partially responsible for the huge growth of the chemical industry during the 20th century.

As a simple example of exergy, air at atmospheric conditions of temperature, pressure, and composition contains energy but no exergy when it is chosen as the thermodynamic reference state known as ambient. Individual processes on Earth such as combustion in a power plant often eventually result in products that are incorporated into the atmosphere, so defining this reference state for exergy is useful even though the atmosphere itself is not at equilibrium and is full of long and short term variations.

If standard ambient conditions are used for calculations during chemical plant operation when the actual weather is very cold or hot, then certain parts of a chemical plant might seem to have an exergy efficiency of greater than 100%. Without taking into account the non-standard atmospheric temperature variation, these calculations can give an impression of being a perpetual motion machine. Using actual conditions will give actual values, but standard ambient conditions are useful for initial design calculations.

Applications in natural resource utilization
In recent decades, utilization of exergy has spread outside of physics and engineering to the fields of industrial ecology, ecological economics, systems ecology, and energetics. Defining where one field ends and the next begins is a matter of semantics, but applications of exergy can be placed into rigid categories. After the milestone work of Jan Szargut who emphasized the relation between exergy and availability, it is necessary to remember "Exergy Ecology and Democracy". by Goran Wall, a short essay, which evidences the strict relation that relates exergy disruption with environmental and social disruption. From this activity it has derived a fundamental research activity in ecological economics and environmental accounting perform exergy-cost analyses in order to evaluate the impact of human activity on the current and future natural environment. As with ambient air, this often requires the unrealistic substitution of properties from a natural environment in place of the reference state environment of Carnot. For example, ecologists and others have developed reference conditions for the ocean and for the Earth's crust. Exergy values for human activity using this information can be useful for comparing policy alternatives based on the efficiency of utilizing natural resources to perform work. Typical questions that may be answered are:

 * Does the human production of one unit of an economic good by method A utilize more of a resource's exergy than by method B?

 * Does the human production of economic good A utilize more of a resource's exergy than the production of good B?

 * Does the human production of economic good A utilize a resource's exergy more efficiently than the production of good B?

There has been some progress in standardizing and applying these methods.

Measuring exergy requires the evaluation of a system's reference state environment. With respect to the applications of exergy on natural resource utilization, the process of quantifying a system requires the assignment of value (both utilized and potential) to resources that are not always easily dissected into typical cost-benefit terms. However, to fully realize the potential of a system to do work, it is becoming increasingly imperative to understand exergetic potential of natural resources, and how human interference alters this potential.

Referencing the inherent qualities of a system in place of a reference state environment is the most direct way that ecologists determine the exergy of a natural resource. Specifically, it is easiest to examine the thermodynamic properties of a system, and the reference substances that are acceptable within the reference environment. This determination allows for the assumption of qualities in a natural state: deviation from these levels may indicate a change in the environment caused by outside sources. There are three kinds of reference substances that are acceptable, due to their proliferation on the planet: gases within the atmosphere, solids within the Earth's crust, and molecules or ions in seawater. By understanding these basic models, it's possible to determine the exergy of multiple earth systems interacting, like the effects of solar radiation on plant life. These basic categories are utilized as the main components of a reference environment when examining how exergy can be defined through natural resources.

Other qualities within a reference state environment include temperature, pressure, and any number of combinations of substances within a defined area. Again, the exergy of a system is determined by the potential of that system to do work, so it is necessary to determine the baseline qualities of a system before it is possible to understand the potential of that system. The thermodynamic value of a resource can be found by multiplying the exergy of the resource by the cost of obtaining the resource and processing it.

Today, it is becoming increasingly popular to analyze the environmental impacts of natural resource utilization, especially for energy usage. To understand the ramifications of these practices, exergy is utilized as a tool for determining the impact potential of emissions, fuels, and other sources of energy. Combustion of fossil fuels, for example, is examined with respect to assessing the environmental impacts of burning coal, oil, and natural gas. The current methods for analyzing the emissions from these three products can be compared to the process of determining the exergy of the systems affected; specifically, it is useful to examine these with regard to the reference state environment of gases within the atmosphere. In this way, it is easier to determine how human action is affecting the natural environment.

Applications in sustainability
In systems ecology, researchers sometimes consider the exergy of the current formation of natural resources from a small number of exergy inputs (usually solar radiation, tidal forces, and geothermal heat). This application not only requires assumptions about reference states, but it also requires assumptions about the real environments of the past that might have been close to those reference states. Can we decide which is the most "realistic impossibility" over such a long period of time when we are only speculating about the reality?

For instance, comparing oil exergy to coal exergy using a common reference state would require geothermal exergy inputs to describe the transition from biological material to fossil fuels during millions of years in the Earth's crust, and solar radiation exergy inputs to describe the material's history before then when it was part of the biosphere. This would need to be carried out mathematically backwards through time, to a presumed era when the oil and coal could be assumed to be receiving the same exergy inputs from these sources. A speculation about a past environment is different from assigning a reference state with respect to known environments today. Reasonable guesses about real ancient environments may be made, but they are untestable guesses, and so some regard this application as pseudoscience or pseudo-engineering.

The field describes this accumulated exergy in a natural resource over time as embodied energy with units of the "embodied joule" or "emjoule".

The important application of this research is to address sustainability issues in a quantitative fashion through a sustainability measurement:

 * Does the human production of an economic good deplete the exergy of Earth's natural resources more quickly than those resources are able to receive exergy?

 * If so, how does this compare to the depletion caused by producing the same good (or a different one) using a different set of natural resources?

Exergy and environmental policy
Today environmental policies does not consider exergy as an instrument for a more equitable and effective environmental policy. Recently, exergy analysis allowed to obtain an important fault in today governmental GHGs emission balances, which often do not consider international transport related emissions, therefore the impacts of import/export are not accounted,

Therefore, some preliminary cases of the impacts of import export transportation and of technology had provided evidencing the opportunity of introducing an effective exergy based taxation which can reduce the fiscal impact on citizens. In addition Exergy can be a precious instrument for an effective estimation of the path toward UN sustainable development goals (SDG).

Assigning one thermodynamically obtained value to an economic good
A technique proposed by systems ecologists is to consolidate the three exergy inputs described in the last section into the single exergy input of solar radiation, and to express the total input of exergy into an economic good as a solar embodied joule or sej. (See Emergy) Exergy inputs from solar, tidal, and geothermal forces all at one time had their origins at the beginning of the solar system under conditions which could be chosen as an initial reference state, and other speculative reference states could in theory be traced back to that time. With this tool we would be able to answer:

 * What fraction of the total human depletion of the Earth's exergy is caused by the production of a particular economic good?

 * What fraction of the total human and non-human depletion of the Earth's exergy is caused by the production of a particular economic good?

No additional thermodynamic laws are required for this idea, and the principles of energetics may confuse many issues for those outside the field. The combination of untestable hypotheses, unfamiliar jargon that contradicts accepted jargon, intense advocacy among its supporters, and some degree of isolation from other disciplines have contributed to this protoscience being regarded by many as a pseudoscience. However, its basic tenets are only a further utilization of the exergy concept.

Implications in the development of complex physical systems
A common hypothesis in systems ecology is that the design engineer's observation that a greater capital investment is needed to create a process with increased exergy efficiency is actually the economic result of a fundamental law of nature. By this view, exergy is the analogue of economic currency in the natural world. The analogy to capital investment is the accumulation of exergy into a system over long periods of time resulting in embodied energy. The analogy of capital investment resulting in a factory with high exergy efficiency is an increase in natural organizational structures with high exergy efficiency. (See Maximum power). Researchers in these fields describe biological evolution in terms of increases in organism complexity due to the requirement for increased exergy efficiency because of competition for limited sources of exergy.

Some biologists have a similar hypothesis. A biological system (or a chemical plant) with a number of intermediate compartments and intermediate reactions is more efficient because the process is divided up into many small substeps, and this is closer to the reversible ideal of an infinite number of infinitesimal substeps. Of course, an excessively large number of intermediate compartments comes at a capital cost that may be too high.

Testing this idea in living organisms or ecosystems is impossible for all practical purposes because of the large time scales and small exergy inputs involved for changes to take place. However, if this idea is correct, it would not be a new fundamental law of nature. It would simply be living systems and ecosystems maximizing their exergy efficiency by utilizing laws of thermodynamics developed in the 19th century.

Philosophical and cosmological implications
Some proponents of utilizing exergy concepts describe them as a biocentric or ecocentric alternative for terms like quality and value. The "deep ecology" movement views economic usage of these terms as an anthropocentric philosophy which should be discarded. A possible universal thermodynamic concept of value or utility appeals to those with an interest in monism.

For some, the result of this line of thinking about tracking exergy into the deep past is a restatement of the cosmological argument that the universe was once at equilibrium and an input of exergy from some First Cause created a universe full of available work. Current science is unable to describe the first 10−43 seconds of the universe (See Timeline of the Big Bang). An external reference state is not able to be defined for such an event, and (regardless of its merits), such an argument may be better expressed in terms of entropy.

Quality of energy types
The ratio of exergy to energy in a substance can be considered a measure of energy quality. Forms of energy such as macroscopic kinetic energy, electrical energy, and chemical Gibbs free energy are 100% recoverable as work, and therefore have exergy equal to their energy. However, forms of energy such as radiation and thermal energy can not be converted completely to work, and have exergy content less than their energy content. The exact proportion of exergy in a substance depends on the amount of entropy relative to the surrounding environment as determined by the Second Law of Thermodynamics.

Exergy is useful when measuring the efficiency of an energy conversion process. The exergetic, or 2nd Law, efficiency is a ratio of the exergy output divided by the exergy input. This formulation takes into account the quality of the energy, often offering a more accurate and useful analysis than efficiency estimates only using the First Law of Thermodynamics.

Work can be extracted also from bodies colder than the surroundings. When the flow of energy is coming into the body, work is performed by this energy obtained from the large reservoir, the surrounding. A quantitative treatment of the notion of energy quality rests on the definition of energy. According to the standard definition, Energy is a measure of the ability to do work. Work can involve the movement of a mass by a force that results from a transformation of energy. If there is an energy transformation, the second principle of energy flow transformations says that this process must involve the dissipation of some energy as heat. Measuring the amount of heat released is one way of quantifying the energy, or ability to do work and apply a force over a distance.

Exergy of heat available at a temperature
Maximal possible conversion of heat to work, or exergy content of heat, depends on the temperature at which heat is available and the temperature level at which the reject heat can be disposed, that is the temperature of the surrounding. The upper limit for conversion is known as Carnot efficiency and was discovered by Nicolas Léonard Sadi Carnot in 1824. See also Carnot heat engine.

Carnot efficiency is

where TH is the higher temperature and TC is the lower temperature, both as absolute temperature. From Equation 15 it is clear that in order to maximize efficiency one should maximize TH and minimize TC.

Exergy exchanged is then:

where Tsource is the temperature of the heat source, and To is the temperature of the surrounding.

Connection with economic value
Exergy in a sense can be understood as a measure of the value of energy. Since high-exergy energy carriers can be used for more versatile purposes, due to their ability to do more work, they can be postulated to hold more economic value. This can be seen in the prices of energy carriers, i.e. high-exergy energy carriers such as electricity tend to be more valuable than low-exergy ones such as various fuels or heat. This has led to the substitution of more valuable high-exergy energy carriers with low-exergy energy carriers, when possible. An example is heating systems, where higher investment to heating systems allows using low-exergy energy sources. Thus high-exergy content is being substituted with capital investments.

Exergy based Life Cycle Assessment (LCA)
Exergy of a system is the maximum useful work possible during a process that brings the system into equilibrium with a heat reservoir. Wall clearly states the relation between exergy analysis and resource accounting. This intuition confirmed by Dewulf Sciubba lead to exergo-economic accounting and to methods specifically dedicated to LCA such as exergetic material input per unit of service (EMIPS). The concept of material input per unit of service (MIPS) is quantified in terms of the second law of thermodynamics, allowing the calculation of both resource input and service output in exergy terms. This exergetic material input per unit of service (EMIPS) has been elaborated for transport technology. The service not only takes into account the total mass to be transported and the total distance, but also the mass per single transport and the delivery time. The applicability of the EMIPS methodology relates specifically to the transport system and allows an effective coupling with life cycle assessment. The exergy analysis according to EMIPS allowed the definition of a precise strategy for reducing environmental impacts of transport toward more sustainable transport. Such a strategy requires the reduction of the weight of vehicles, sustainable styles of driving, reducing the friction of tires, encouraging electric and hybrid vehicles, improving the walking and cycling environment in cities, and by enhancing the role of public transport, especially electric rail.

Carnot
In 1824, Sadi Carnot studied the improvements developed for steam engines by James Watt and others. Carnot utilized a purely theoretical perspective for these engines and developed new ideas. He wrote: "The question has often been raised whether the motive power of heat is unbounded, whether the possible improvements in steam engines have an assignable limit—a limit by which the nature of things will not allow to be passed by any means whatever... In order to consider in the most general way the principle of the production of motion by heat, it must be considered independently of any mechanism or any particular agent. It is necessary to establish principles applicable not only to steam-engines but to all imaginable heat-engines... The production of motion in steam-engines is always accompanied by a circumstance on which we should fix our attention. This circumstance is the re-establishing of equilibrium... Imagine two bodies A and B, kept each at a constant temperature, that of A being higher than that of B. These two bodies, to which we can give or from which we can remove the heat without causing their temperatures to vary, exercise the functions of two unlimited reservoirs..."

Carnot next described what is now called the Carnot engine, and proved by a thought experiment that any heat engine performing better than this engine would be a perpetual motion machine. Even in the 1820s, there was a long history of science forbidding such devices. According to Carnot, "Such a creation is entirely contrary to ideas now accepted, to the laws of mechanics and of sound physics. It is inadmissible."

This description of an upper bound to the work that may be done by an engine was the earliest modern formulation of the second law of thermodynamics. Because it involves no mathematics, it still often serves as the entry point for a modern understanding of both the second law and entropy. Carnot's focus on heat engines, equilibrium, and heat reservoirs is also the best entry point for understanding the closely related concept of exergy.

Carnot believed in the incorrect caloric theory of heat that was popular during his time, but his thought experiment nevertheless described a fundamental limit of nature. As kinetic theory replaced caloric theory through the early and mid-19th century (see Timeline of thermodynamics), several scientists added mathematical precision to the first and second laws of thermodynamics and developed the concept of entropy. Carnot's focus on processes at the human scale (above the thermodynamic limit) led to the most universally applicable concepts in physics. Entropy and the second-law are applied today in fields ranging from quantum mechanics to physical cosmology.

Gibbs
In the 1870s, Josiah Willard Gibbs unified a large quantity of 19th century thermochemistry into one compact theory. Gibbs's theory incorporated the new concept of a chemical potential to cause change when distant from a chemical equilibrium into the older work begun by Carnot in describing thermal and mechanical equilibrium and their potentials for change. Gibbs's unifying theory resulted in the thermodynamic potential state functions describing differences from thermodynamic equilibrium.

In 1873, Gibbs derived the mathematics of "available energy of the body and medium" into the form it has today. (See the equations above). The physics describing exergy has changed little since that time.

Helmholtz
In the 1880s, German scientist Hermann von Helmholtz derived the equation for the maximum work which can be reversibly obtained from a closed system.

Rant
In 1956, Yugoslav scholar Zoran Rant proposed the concept of Exergy, extending Gibbs and Helmholtz' work. Since then, continuous development in exergy analysis has seen many applications in thermodynamics, and exergy has been accepted as the maximum theoretical useful work which can be obtained from a system with respect to its environment.

title: Exergy


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Zlatoust

Zlatoust (Златоуст; ) is a city in Chelyabinsk Oblast, Russia, located on the Ay River (in the Kama basin), 160 km west of Chelyabinsk. Population:   181,000 (1971); 161,000 (1959); 99,000 (1939); 48,000 (1926); 21,000 (1910).

Etymology
Apparently, the city's name is derived from the Russian translation of "Chrysostom", literally "golden-mouthed" in the original Greek, for the eloquent Saint John Chrysostom, because the city was founded near a church dedicated to that saint. In other languages the city is sometimes called Ызлататыс (Izlataltıs) or Зылатаус (Zılataus) in Tatar and Залатауыс in Bashkir.

History

Zlatoust was founded in 1754 due to the construction of the ironworks. In 1774–76, the workers of the plant took part in the insurrection led by Yemelyan Pugachev. In the early 19th century, Pavel Anosov made the first Russian bulat steel blades in Zlatoust. It was granted town status in 1865. From 1865 to 1919 Zlatoust was part of Ufa Governorate. The town is also known for the first cannons made of Russian steel. In 1903, the Tsarist authorities brutally suppressed a strike, organized by the workers of Zlatoust.

In 1815, an arms factory was built here, which began to produce sabres and swords. To establish production, more than a hundred experts were invited from renowned arms centers in Europe, including Solingen and Klingenthal (Germany). In summer 1816, the first batch of Zlatoust blades was sent to Saint-Petersburg, both combat weapons and decorated samples. Famous artists Ivan Bushuyev and Ivan Boyarshinov authored unique patterns of cold-steel decorated with engravings. Bushuyev's and Boyarshinov's swords are very rare; under 2 dozen are believed to exist today, all in Russian state museums and wealthy Russians' collections (rare published example). The flying winged horse was a favorite element of many of Bushuyev's engravings, so he was given a nickname Ivan the Wingy (Ivanko Krylatko). Since then, a pegasus has been an emblem of the town. In the 1840s the engraving was shifted onto decorative metal plates. This idea was suggested by Zlatoust factory's director - Pavel Petrovich Anosov, who was taking care of facory's profit and decided to expand the product range. Since then Zlatoust engraving on household items and tableware became popular. The Soviets gained control over Zlatoust in March 1918. The town was occupied by the Whites between June 1918 and July 1919. On 13 July 1919, Zlatoust was seized by the Red Army.

During the Soviet period, Zlatoust became an industrial city, which specialized in metallurgy, mechanical engineering, tool-making, food production, and other industries. Zlatoust is one of the centers of artistic engraving on metal in Russia. Traditionally, such engravings were done on weapons, such as knives, swords and tableware. Zlatoust engraving on metal received an impulse to a new development, when in the 1960s young graduates of art Zlatoust schools started to work at the factory and reveal their talents.

Administrative and municipal status
Within the framework of administrative divisions, it is, together with nine rural localities, incorporated as the City of Zlatoust—an administrative unit with the status equal to that of the districts. As a municipal division, the City of Zlatoust is incorporated as Zlatoustovsky Urban Okrug.

Notable people

 * Boris Shaposhnikov, Marshal of the Soviet Union
 * Lidiya Skoblikova, Olympic and World Championship winning speed-skater
 * Anatoly Karpov, former world chess champion
 * Svetlana Ishmouratova, 2006 Olympic Gold Medalist biathlete
 * Alexander Mordukhovich, composer
 * Yuri Mikhailovich Vyshinsky, filmmaker and screenwriter
 * Alyona Shvets, pop singer

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Zlatoust


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User:Kate/membership opt-out

Membership of the Wikimedia Foundation:
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Therefore:
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The ideal implementation of this is:
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title: User:Kate/membership opt-out


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Gyaincain Norbu

Chökyi Gyalpo, also referred to by his secular name Gyaincain Norbu or Gyaltsen Norbu (born 13 February 1990), is considered the 11th Panchen Lama by the government of the People's Republic of China (PRC). He is also the vice president of the Buddhist Association of China. Gyalpo is considered by critics to be a proxy of the Chinese government.

Gyalpo's position as Panchen Lama is disputed by the earlier recognition of Gedhun Choekyi Nyima, by the 14th Dalai Lama. Gedhun Choekyi Nyima, along with his family and Chadrel Rinpoche, the then-incumbent Khenpo of Tashi Lhunpo Monastery, were kidnapped and/or arrested then detained in one or more unknown locations by the Chinese government in the days following the Dalai Lama's official recognition of Gedhun Choekyi Nyima. The Tibetan administration in exile (Central Tibetan Administration) does not recognize the Chinese government's selection using the Golden Urn, but some monks in Chinese-controlled Tibetan monasteries do refer to the Chinese government's selection as the Panchen Lama.

Names
Gyaincain Norbu's full religious name is Jêzün Lobsang Qamba Lhünzhub Qögyi'gyäbo Bäsangbo, although he is generally called Qoigyijabu. Meaning "Dharma king", this name can also be written Qögyi'gyäbo, Qögyi Gyäbo, Qoigyi'gyaibo, Qoigyi Gyaibo, Chökyi Gyalpo, Choekyi Gyalpo, or, in Wylie transliteration, Chos-kyi Rgyal-po. The Chinese equivalent is Quèjí Jiébù (确吉杰布).

The secular name, Gyaincain Norbu, can also be written Gyaencaen Norbu, Gyancain Norbu, or Gyaltsen Norbu.

Biography
Gyaincain Norbu was born on 13 February 1990 in Lhari County in northern Tibet Autonomous Region. He had been living in Beijing during his early childhood to be educated in a Chinese way, and travelled to Tashilhunpo Monastery for his enthronement in November/December 1995, in Shigatse, the official seat of the Panchen Lamas. Since his selection by the Chinese government as the Panchen Lama he has studied Tibetan Buddhism; to his studies he added Tibetan language, sutra, and logic at ten, and he is bilingual in both Tibetan and Chinese. He spent most of his later childhood studying Buddhism in Beijing. In a rare appearance for his adolescent age, Norbu delivered a speech in Tibetan for the opening ceremony of the 2006 World Buddhist Forum about Buddhism and national unity. One Western press outlet reported a cold reception among delegates, with fellow Buddhists making no attempt to greet Gyaltsen Norbu during greeting ceremonies ahead of the conference on Wednesday. Tenzin Gyatso, the 14th Dalai Lama had not been invited, because he is viewed by China as "a long-time stubborn secessionist who has tried to split his Chinese motherland and break the unity among different ethnic groups."

Two years later, in 2008, he denounced anti-Han riots in Lhasa, saying "We resolutely oppose all activities to split the country and undermine ethnic unity". China sees him as "the public face of Tibetan Buddhism".

On 3 February 2010, Norbu was elected vice president of the Buddhist Association of China. Later that month, at 20 years old, Norbu became the youngest member of the advisory body National Committee of the Chinese People's Political Consultative Conference (CPPCC). Vice chairman of the Tibet Autonomous Region Hao Peng praised his appointment, in particular for Norbu's "demonstrating the role of the living Buddhas in Tibetan Buddhism and encouraging more believers to participate in state affairs". He was not, however, made vice chairman of the CPPCC, as Choekyi Gyaltsen, 10th Panchen Lama was and was widely expected of Norbu. Still, the Tibetan government in exile expressed concern that his appointment could prejudice his position on the next Dalai Lama, who normally requires approval from the Panchen Lama.

In May 2010, he reported to the ethnically Tibetan earthquake zone of the 2010 Yushu earthquake and held prayer services for victims. In June, he gave speeches at Tibet University and Tibet University of Traditional Tibetan Medicine in Lhasa promoting the value of education. In response to the 2010 Gansu mudslide, in which Zhugqu County, a third of which is populated by Tibetans, was hit, he donated ¥50,000 to relief efforts and prayed for the victims. He pays visits to the Tashilhunpo Monastery, the traditional seat of the Panchen Lama, although he does not live there. The Asia Times describes him as "A slight man who wears thick glasses and traditional crimson robes".

In Hong Kong on 26 April 2012 Gyaincain gave his first appearance outside of mainland China to address over a thousand monks at the Third World Buddhist Forum on the topic of Dharma.

Selection
Following the death of the Choekyi Gyaltsen, 10th Panchen Lama in 1989, both the Tibetan government in exile and the Chinese government started parallel processes in the six-year-long search for the 11th Panchen Lama.

The head of the Chinese government's Panchen Lama search committee at the time, Chadrel Rinpoche, was able to secretly communicate with the Dalai Lama. He planned to submit the Dalai Lama's favored choice to the government. When the government learned of this, they arrested Chadrel in May 1995. The Dalai Lama moved to pre-empt China's choice, and proclaimed his own preferred candidate, Gedhun Choekyi Nyima, as the 11th incarnation of the Panchen Lama. Four days later, Chinese security forces escorted him from his home in Lhari County, stating that he "was at risk of being kidnapped by Tibetan separatists". China rejects Nyima as being "arbitrarily" chosen, while the Tibetan government in exile similarly insists on its candidate's legitimacy.

Chadrel was replaced on the search committee by Sengchen Lobsang Gyaltsen. The new committee decided to choose the Panchen Lama from a list of finalists by drawing lots from a Golden Urn. The Chinese custom of using the Golden Urn had been introduced in the year 1792 by the Qianlong Emperor and used to select the 10th, 11th, and 12th Dalai Lamas. Four days before his death, the China Tibet Information Center reports, the 10th Panchen Lama requested that the Golden Urn process be used to select his successor. According to Arjia Rinpoche, an important lama who attended the ceremony, Ye Xiaowen, the central government official in charge of the Panchen Lama issue, stated privately that the selection had been rigged in favor of Gyaincain Norbu.

Six-year-old Gyaincain Norbu was selected on 8 December 1995 with the religious name Qoigyijabu. Exiled Tibetan abbot Arjia Rinpoche, alleges that an official told him that the ceremony, which he attended, was rigged in favor of Norbu. Gyaincain Norbu was enthroned at Tashilhunpo Monastery and has since assumed the full functions of Panchen Lama. In attendance at the enthronement was the 8th Arjia Rinpoche, who in his book says, "We had to prostrate to the so-called Panchen Lama...we had neither the respect for nor faith in this chosen child... I felt soiled by this gesture."

Diplomatic meetings
On 14 September 2010, the foreign minister of Singapore, George Yeo, became the first foreign member of government to meet officially with Gyaincain Norbu, at the Xihuang Monastery in Beijing.

title: Gyaincain Norbu


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Bouncing Off the Satellites

Bouncing off the Satellites is the fourth studio album by American new wave band the B-52's, released on September 8, 1986, by Warner Bros. Records. It was recorded in July 1985 and was produced by Tony Mansfield. Founding member and guitarist Ricky Wilson died of AIDS after most of the work on the album was completed, but a year prior to its release. The B-52's had gone on hiatus by the time Bouncing Off the Satellites was released, and it took three years for the band to recover from Wilson's death and release their next studio album, Cosmic Thing.

Recording
Bouncing off the Satellites was recorded in July 1985.

According to Kate Pierson, "Wig" was written and recorded after the band's label, Warner Bros., asked them to write a hit song for the album. The band had the title in mind for years and devised the song via a jam session.

A backwards message was deliberately inserted into the song "Detour Thru Your Mind": in the last 30 seconds of the track, Fred Schneider says, "I buried my parakeet in the backyard. Oh no, you're playing the record backwards. Watch out, you might ruin your needle."

Death of Ricky Wilson
During the recording, guitarist Ricky Wilson was suffering from AIDS. Keith Strickland was the only bandmate who was informed of Wilson's illness. Strickland later stated that Wilson "was very protective, particularly of Cindy and his family", due to the public's misconceptions about AIDS.

On October 12, 1985, Wilson finally succumbed to the illness, at the age of 32. Pierson has stated that Wilson worked on the album in its entirety prior to his death, and that it was completed. Strickland later recalled, "After Ricky Wilson died, we felt that the band was finished. We couldn't imagine continuing without him. So, we each went our separate ways." The band took a hiatus from their musical careers until they reformed in 1988 for the recording of their next studio album, Cosmic Thing.

Release and promotion
The album was finally released on September 8, 1986. Devastated at Wilson's death, the band did not tour and were involved in minimal promotion for the album. However, the band did produce a music video for "Girl from Ipanema Goes to Greenland", which Schneider has stated was both "bittersweet" and the best video they ever made.

Pierson later stated, "Warner Bros. figured since we weren't touring after Ricky died that they would just not promote the record. We all went through so many changes—especially without touring, and the record just dropped like a stone—and we all dealt with our grief." Pierson also theorized that the label did not promote the album because the band stated they had no intention of hiring a new guitar player to replace Wilson, thus the label assumed the band would not continue on without him. However, on August 5, 1987, the band appeared on the British ITV show Hold Tight!, miming to the song "Wig", with Strickland now on guitar and Ralph Carney credited on-screen for drums. Carney had previously played saxophone on the B-52's' Mesopotamia (1982) and Whammy! (1983) releases, and had subsequently toured with the band.

Commercial
Despite the relative lack of promotion, "Summer of Love" was released as the lead single and initially received a considerable amount of airplay from some radio stations, managing to peak at No. 3 on the Billboard Dance Club Songs chart. Pierson later recalled that Warner Bros. employee Steve Baker had tried to get the label to promote the album in light of the single's success, to no avail. Subsequently, the album only reached No. 85 on the Billboard 200 chart.

Critical
Robert Christgau of The Village Voice felt Wilson's and Pierson's contributions to the album were "watercolors posing as Kenny Scharfs—not only don't 'Summer of Love' and 'She Brakes for Rainbows' redeem anybody's '60s retro, they don't even take off on it", adding that "Fred's abrasive camp saves the day". Trouser Press opined, "The first side is entirely delightful, filled with such classic B-52 silliness as 'Wig,' 'Detour Thru Your Mind' and 'Girl from Ipanema Goes to Greenland,' but the flip is overly smooth, limp and uninspired."

In a retrospective review for AllMusic, Stephen Thomas Erlewine stated, "Considering their loss, it's not surprising that the B-52's don't sound entirely focused throughout the record", adding that "There are so many musicians on the record that it winds up sounding too carefully considered -- the polar opposite of the loose, inspired fun of their early work." Similarly, in The New Rolling Stone Album Guide (2004), J.D. Considine felt the album "flops miserably" and sounded "hollow and contrived", due to the addition of session players. Rich Wilhelm of PopMatters called the album "wistful" and "subdued", concluding that it was "the most subtle of the B-52s' albums, with the loss of Ricky Wilson adding to the album's poignancy." The Spectator felt the album was darker and more melancholy than the band's previous work.

Personnel
The B-52's
 * Cindy Wilson – vocals (1–2, 4–7, 9–10)
 * Kate Pierson – vocals (1, 3–6, 9), organ (3)
 * Fred Schneider – vocals (4–6, 8–9)
 * Ricky Wilson – guitars (1–2, 7, 9), bass (4–6), vocals (6), backing vocals (7)
 * Keith Strickland – bass (1, 2, 9, 10), keyboards (2, 4, 6–7, 9–10), guitars (3–7), percussion (3), sitar (5), vocals (6), harmonica (7), backing vocals (7, 10)

Additional musicians
 * Tony Mansfield – Fairlight CMI
 * Mark Mazur – guitars (3), bass (3)
 * Tim Rollins – guitars (3)
 * John Coté – all other instruments (8), backing vocals (8)
 * Tom Beckerman – lead guitar (8)

Technical
 * Tony Mansfield – producer
 * Shep Pettibone – additional production (1, 2), remixing (1)
 * Michael Hutchinson – engineer (1)
 * Steve Peck – engineer (2)
 * Tony Phillips – engineer (3-10)
 * Fernando Kral – assistant engineer
 * Don Peterkofsky – assistant engineer
 * Phil Brown – mastering at K Disc Mastering (Hollywood, California)
 * Andrea Starr – coordinator
 * Matthew Murphy – coordinator
 * Pat Sabatino – coordinator
 * Keith Strickland – back cover photography
 * Kenny Scharf – front cover painting
 * Keith Bennett/Kav Deluxe – art direction

title: Bouncing Off the Satellites


text:
Talk:Bouncing Off the Satellites

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No one's credited for drums
Had Strickland completely stopped by this point or is that an oversight? - Immigrant laborer (talk) 01:51, 12 October 2017 (UTC)

title: Talk:Bouncing Off the Satellites


text: Category:Iranian generals

title: Category:Iranian generals


text:
Cluster decomposition

In physics, the cluster decomposition property states that experiments carried out far from each other cannot influence each other. Usually applied to quantum field theory, it requires that vacuum expectation values of operators localized in bounded regions factorize whenever these regions becomes sufficiently distant from each other. First formulated by Eyvind Wichmann and James H. Crichton in 1963 in the context of the S-matrix, it was conjectured by Steven Weinberg that in the low energy limit the cluster decomposition property, together with Lorentz invariance and quantum mechanics, inevitably lead to quantum field theory. String theory satisfies all three of the conditions and so provides a counter-example against this being true at all energy scales.

Formulation
The S-matrix $$S_{\beta \alpha}$$ describes the amplitude for a process with an initial state $$\alpha$$ evolving into a final state $$\beta$$. If the initial and final states consist of two clusters, with $$\alpha_1$$ and $$\beta_1$$ close to each other but far from the pair $$\alpha_2$$ and $$\beta_2$$, then the cluster decomposition property requires the S-matrix to factorize

S_{\beta \alpha} \rightarrow S_{\beta_1 \alpha_1}S_{\beta_2\alpha_2} $$

as the distance between the two clusters increases. The physical interpretation of this is that any two spatially well separated experiments $$\alpha_1 \rightarrow \beta_1$$ and $$\alpha_2 \rightarrow \beta_2$$ cannot influence each other. This condition is fundamental to the ability to doing physics without having to know the state of the entire universe. By expanding the S-matrix into a sum of a product of connected S-matrix elements $$S_{\beta \alpha}^c$$, which at the perturbative level are equivalent to connected Feynman diagrams, the cluster decomposition property can be restated as demanding that connected S-matrix elements must vanish whenever some of its clusters of particles are far apart from each other.

This position space formulation can also be reformulated in terms of the momentum space S-matrix $$\tilde S^c_{\beta \alpha}$$. Since its Fourier transformation gives the position space connected S-matrix, this only depends on position through the exponential terms. Therefore, performing a uniform translation in a direction $$\boldsymbol a$$ on a subset of particles will effectively change the momentum space S-matrix as

\tilde S_{\beta \alpha}^c \xrightarrow{\boldsymbol x_i \rightarrow \boldsymbol x_i+\boldsymbol a} e^{i\boldsymbol a\cdot (\sum_i \boldsymbol p_i)} \tilde S_{\beta \alpha}^c. $$

By translational invariance, a translation of all particles cannot change the S-matrix, therefore $$\tilde S_{\beta \alpha}$$ must be proportional to a momentum conserving delta function $$\delta (\Sigma \boldsymbol p)$$ to ensure that the translation exponential factor vanishes. If there is an additional delta function of only a subset of momenta corresponding to some cluster of particles, then this cluster can be moved arbitrarily far through a translation without changing the S-matrix, which would violate cluster decomposition. This means that in momentum space the property requires that the S-matrix only has a single delta function.

Cluster decomposition can also be formulated in terms of correlation functions, where for any two operators $$\mathcal O_1(x)$$ and $$\mathcal O_2(x)$$ localized to some region, the vacuum expectation values factorize as the two operators become distantly separated

\lim_{|\boldsymbol x|\rightarrow \infty}\langle \mathcal O_1(\boldsymbol x)\mathcal O_2(0)\rangle \rightarrow \langle \mathcal O_1\rangle \langle \mathcal O_2 \rangle. $$

This formulation allows for the property to be applied to theories that lack an S-matrix such as conformal field theories. It is in terms of these Wightman functions that the property is usually formulated in axiomatic quantum field theory. In some formulations, such as Euclidean constructive field theory, it is explicitly introduced as an axiom.

Properties
If a theory is constructed from creation and annihilation operators, then the cluster decomposition property automatically holds. This can be seen by expanding out the S-matrix as a sum of Feynman diagrams which allows for the identification of connected S-matrix elements with connected Feynman diagrams. Vertices arise whenever creation and annihilation operators commute past each other leaving behind a single momentum delta function. In any connected diagram with V vertices, I internal lines and L loops, I-L of the delta functions go into fixing internal momenta, leaving V-(I-L) delta functions unfixed. A form of Euler's formula states that any graph with C disjoint connected components satisfies C = V-I+L. Since the connected S-matrix elements correspond to C=1 diagrams, these only have a single delta function and thus the cluster decomposition property, as formulated above in momentum space in terms of delta functions, holds.

Microcausality, the locality condition requiring commutation relations of local operators to vanish for spacelike separations, is a sufficient condition for the S-matrix to satisfy cluster decomposition. In this sense cluster decomposition serves a similar purpose for the S-matrix as microcausality does for fields, preventing causal influence from propagating between regions that are distantly separated. However, cluster decomposition is weaker than having no superluminal causation since it can be formulated for classical theories as well.

One key requirement for cluster decomposition is that it requires a unique vacuum state, with it failing if the vacuum state is a mixed state. The rate at which the correlation functions factorize depends on the spectrum of the theory, where if it has mass gap of mass $$m$$ then there is an exponential falloff $$\langle \phi(x) \phi(0)\rangle \sim e^{-m|x|}$$ while if there are massless particles present then it can be as slow as $$1/|x|^2$$.

title: Cluster decomposition


text:
George Gordon McCrae

George Gordon McCrae (29 May 1833 – 15 August 1927) was an Australian poet.

Early life
McCrae was born in Leith, Scotland; his father was Andrew Murison McCrae, a writer; his mother was Georgiana McCrae, a painter. George attended a preparatory school in London, and later received lessons from his mother. Georgiana and her four sons emigrated to Melbourne in 1841 following her husband who emigrated in 1839.

Career
After a few years as a surveyor, McCrae joined the Victorian Government service, eventually becoming Deputy Registrar-General, and also a prominent figure in literary circles. Most of his leisure time was spent in writing. His first published work was Two Old Men's Tales of Love and War (London, 1865).

His son Hugh McCrae, also a poet, produced a volume of memoirs (My Father and My Father's Friends) about George and his association with such literary figures as Henry Kendall, Adam Lindsay Gordon, Richard Henry Horne and Marcus Clarke.

George McCrae wrote novels, stories, poetry, and travel sketches, and illustrated books. After his retirement, unpublished manuscripts entitled 'Reminiscences—Experiences not Exploits' contain detailed descriptions of events from his youth and present a record of the early European part of Melbourne country-side.

Late life
McCrae died 15 August 1927 at Hawthorn in Melbourne, survived by four of his six children, including Dorothy Frances Perry, also an author.

title: George Gordon McCrae


text:
Talk:Whammy!

Lead needs rewrite
The lead looks like an article in it's own right! Most of its information needs to be consolidated or moved into the body. The lead should then just be a summary of the article.

-- J. Wong (talk) 18:25, 22 November 2011 (UTC)

 * And the lead contains many statements that are not supported by any references or further in the article body. -- J. Wong (talk) 15:15, 23 November 2011 (UTC)

title: Talk:Whammy!


text:
Talk:Wild Planet

Removed opinions.
I removed the following statement and clause from the article, which are opinions that need cites to a specific professional source (i.e., a reviewer) if they are to be included without giving WP:UNDUE to any one review. Feel free to find sources and re-add them with cites!

"The album has a slightly more psychedelic and even paranoid sound than their first."

"... with the tracks having a more slick feeling"

-- J. Wong (talk) 17:30, 22 November 2011 (UTC)

title: Talk:Wild Planet


text:
Talk:Cosmic Thing

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text:
Discreet Music

Discreet Music is the fourth studio album by Brian Eno, and the first released under his full name (as opposed to simply "Eno"). The album is a minimalist work, with the titular A-side consisting of one 30-minute piece featuring synthesizer and tape delay. The B-side features three variations on Canon in D Major by Johann Pachelbel, performed by the Cockpit Ensemble and conducted by Gavin Bryars.

While his earlier collaborations with Robert Fripp and several selections from Another Green World (1975) feature similar ideas, Discreet Music marked a clear step toward the ambient aesthetic Eno would later codify with 1978's Ambient 1: Music for Airports.

Background
Brian Eno's concept of ambient music builds upon a concept composer Erik Satie called "furniture music". This means music that is intended to blend into the ambient atmosphere of the room rather than be directly focused upon. Like Satie's notion of music that could "mingle with the sound of the knives and forks at dinner", Discreet Music was created to play in, and blend with, the subtle background audio of various, or any given, situation.

The inspiration for this album began when Eno was left bed-ridden by an automobile accident and was given an album of eighteenth-century harp music by a visiting friend, Judy Nylon. After she left, according to the Discreet Music liner notes, Eno inadvertently played the harp album almost inaudibly, which "presented what was for me a new way of hearing music — as part of the ambience of the environment". Nylon recalled the event differently: "I put the harp music on and balanced it as best as I could from where I stood; [Eno] caught on immediately to what I was doing and helped me balance the softness of the rain patter with the faint string sound for where he lay in the room. There was no 'ambience by mistake'." Eno related another version in a 2011 interview: "[Nylon] put a record on and then left. The record was much too quiet but I couldn't reach to turn it up and it was raining outside ... I suddenly thought of this idea of making music that didn't impose itself on your space ... but created a sort of landscape you could belong to".

This album is also an experiment in generative composition. His intention was to explore multiple ways to create music with limited planning or intervention. Nicole V. Gagné described the album as "a minimalist work using tape-delay and synthesizer" that would lead to Eno's further experiments in ambient music.

In a 1979 interview with Lester Bangs, Eno called Discreet Music the most successful of his recordings, explaining that it "was done very, very easily, very quickly, very cheaply, with no pain or anguish over anything, and I still like it."

Recording
The A-side of the album is a thirty-minute piece originally intended as a background drone for guitarist Robert Fripp to play over in a series of concerts. Eno set up a synthesizer with built-in memory along with a tape delay system, but was immediately interrupted: "people started knocking on the door, and I was answering the phone and adjusting all this stuff as it ran. I almost made that without listening to it. It was really automatic music." The liner notes contain a diagram of how this piece was created. It begins with two melodic phrases of different lengths played back from a synthesizer's digital recall system. The equipment used in this case was an EMS Synthi AKS, which had a then-exotic, built-in digital sequencer. This signal is then run through a graphic equaliser to occasionally change its timbre. It is then run through an echo unit before being recorded onto a tape machine. The tape runs to the take-up reel of a second machine, and the output of that machine is fed back into the first tape machine which records the overlapped signals. The next day, Fripp visited and Eno accidentally played the piece back at half-speed, thinking that "it was probably one of the best things I’d ever done and I didn’t even realize I was doing it at the time." The second half of the album consists of three related pieces, collectively titled "Three Variations on the Canon in D Major by Johann Pachelbel", performed by the Cockpit Ensemble, and conducted and co-arranged by Gavin Bryars. Bryars later wrote that "the Cockpit Ensemble" was a "catchall name" for the hired studio musicians, as many did not wish to be credited. Eno described the music as the result of a self-generating, self-regulating system, with the input to the system taking the form of two- or four-measure fragments of Pachelbel's canon, and the system being the performers with a set of instructions. Each variation involves a different way of manipulating and overlaying the musical fragments. In the first piece, "Fullness of Wind", the players' tempos are decreased, with the rate of decrease being related to the relative pitch of the instruments, so that lower instruments are slowest. In the second piece, "French Catalogues", groups of notes are associated with time-related directions from different parts of the score. The third piece, "Brutal Ardour", presents the players with sequences of notes that are related but of different lengths. The titles of these pieces were derived from inaccurate French-to-English translations of the liner notes of a version of Pachelbel's Canon performed by the orchestra of Jean-Francois Paillard.

Release
Discreet Music was the third (of four) simultaneous releases on Eno's new Obscure Records label.

This album was re-released on the Virgin label in 2004. On CD reissues, a full minute of silence separates Discreet Music title track from the Pachelbel piece.

Reception and legacy
Reviewing for The Village Voice in June 1977, Robert Christgau stated that the album "encourages a meditative but secular mood (good for hard bits of writing) more effectively than any of the other rock-identified avant-garde music that's come our way". In 1979, Lester Bangs described it as "either the definitive unobtrusively lustrous statement on ambient musics or a wispy treacly bore that defies you to actually pay attention to it [...] depending on your point of view."

Trouser Press described the album as "striking and haunting, filled with beauty and apprehension, paralleling the minimalist music being made by Steve Reich and Philip Glass." AllMusic's Sean Westergaard said it is Eno's "first full foray into what has become known as ambient music," and added that "[the album's] reputation as a groundbreaking and influential work is surpassed only by its placid beauty."

This album was a favourite of David Bowie's, and led to his collaboration with Eno on Bowie's late 1970s Berlin Trilogy.

The "operational diagram" printed on the rear sleeve of Discreet Music would serve as inspiration for other musicians to experiment with tape delay, such as Thomas Leer and Robert Rental on their 1979 album The Bridge.

For the 40th anniversary (2015) of the release of the album, the Canadian music ensemble Contact recorded "Discreet Music" with classical instruments as a seven-part one hour work.

Track listing

 * Side A

 * 1) "Discreet Music" (Eno) – 30:35

 * Side B

Three Variations on the Canon in D Major by Johann Pachelbel (Eno)
 * 1) "Fullness of Wind" – 9:57
 * 2) "French Catalogues" – 5:18
 * 3) "Brutal Ardour" – 8:17

Personnel

 * Brian Eno – synthesizer, keyboards
 * Gavin Bryars – co-arranger and conductor on Side B
 * The Cockpit Ensemble – performer on Side B
 * Technical
 * Brian Eno – producer, photography
 * Peter Kelsey – engineer
 * Simon Heyworth – mastering
 * John Bonis – cover design
 * Andrew Day – redesign

title: Discreet Music


text: Category:Universities and colleges in Pakistan