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A delicate superlattice structure of Cr 2 Te 3 / Bi 2 / Bi 2 Te 3 has been constructed based on the chemical reduction at the interface. The growth was conducted by the molecular beam epitaxy, and the structural characterizations have provided solid evidence of the designed structure. The interfaces between Cr 2 Te 3 , Bi 2 and Bi 2 Te 3 are sharp. The ferromagnetism has been introduced in this system as revealed by the negative magnetoresistance curve and the anomalous Hall effect. [ABSTRACT FROM AUTHOR]

The optimal performance of an engine operating between a finite high-temperature source and an infinite low-temperature reservoir is studied. It is assumed that there exists only the irreversibility of heat conduction in the cycle and heat transfer obeys another linear law [i.e., the heat-flux q∝Δ(1/T)] instead of Newton’s law. It is shown that the optimal configuration of the cycle is composed of two adiabatic processes and two isoheat-flux processes in which the difference of the reciprocal temperature of the working fluid and reservoirs must be maintained constant. Moreover, the relation between the optimal power output and the efficiency of such a cycle is derived, and some new results are deduced from it. The results are compared with the optimal performance of a generalized Carnot cycle for Newton’s heat transfer law. Consequently, the common character and the main difference of a generalized Carnot cycle for the two different heat transfer laws are expounded. [ABSTRACT FROM AUTHOR]

In this paper, the equivalent combined systems of three-heat-source heat pumps are studied. It is pointed out that there may be three combined ways for us to conceive a reversible three-heat-source heat pump as a combined system having a reversible Carnot heat pump driven by a reversible Carnot engine. Whereas for an endoreversible three-heat-source heat pump affected by the heat resistances, there is only one combined way for us to conceive it as a combined system having an endoreversible Carnot heat pump driven by an endoreversible Carnot engine. Then, the fundamental optimum formula of a three-heat-source heat pump is derived simply and directly by using those of two-heat-source cycles. The optimal peformance of an endoreversible three-heat-source heat pump is thus discussed. The inherent relation between the two- and the three-heat-source cycles as well as the fundamental distinction between the reversible and the endoreversible three-heat-source cycles is also revealed. These results may enrich the theory of finite time thermodynamics, and provide some new theoretical bases for the exploitation and application of three-heat-source apparatus such as chemical heat pumps, absorption heat pumps, and so on. [ABSTRACT FROM AUTHOR]

In this paper it is shown that the optimal two-heat-source endoreversible cycle is the endoreversible Carnot cycle for a class of heat-transfer laws. The relation between optimal efficiency and power output of the cycle is derived. By use of this relation, we discuss the optimal performance of an endoreversible Carnot cycle for three common heat-transfer laws, and reveal the dependence of performance on the heat-transfer law and the heat-transfer coefficient. A number of new universal results are derived, and some major conclusions derived in several references are also deduced. [ABSTRACT FROM AUTHOR]

Investigates the effects of the irreversibilities caused by the thermal resistances and regenerative losses on the performance of a magnetic Ericsson refrigeration cycle. Information on fundamental optimum relations and general performance characteristics of the cycle; Calculation of the maximum cooling rate and some important performance parameters; How the optimal operating regions of the cycle were determined.

Provides information on a study that investigated the influence of Thomson heat on the maximum efficiency of a thermoelectric generator by means of nonequilibrium thermodynamics. Equations of heat conduction; Expressions for power output and efficiency; Results and discussion on the study.

Presents a study which examined the maximum performance of the solar-driven heat pump system consisting of a solar collector and a three-heat-source heat pump. Overall coefficient of performance of the system; Optimum operating temperature of the solar collector; Conclusion.

Presents a study which investigated the characteristics of a magnetic Brayton refrigeration cycle on the basis of the general equation of state of a simple paramagnetic salt. Thermodynamic properties of paramagnetic salt; Coefficient of performance of the magnetic Brayton refrigeration cycle; Discussion and conclusion.

Presents a study that examined the characteristics of a magnetic Ericsson refrigeration cycle on the basis of the thermodynamic properties of the ferromagnetic material. Effects of field-dependent heat capacity on regeneration; Discussion on the coefficients of performance of the Ericsson magnetic refrigeration cycle; Use of homogeneous magnetic material.

Offers information on a study which introduced the concepts of generalized polytropic processes and polytropic refrigeration cycles that consist of isothermal processes and generalized polytropic processes of paramagnetic salt. Theoretical background; Computational approach; Results and its implications.

Focuses on a study which investigated the performance of a class of endoreversible-combined refrigeration cycles operating between low-temperature heat reservoir and high-temperature heat reservoir. Model of endoreversible-combined refrigeration cycle; Optimal configuration of endoreversible-combined refrigeration cycles; Relation between optimal coefficient of performance and rate of refrigeration.

On the basis of the probability distribution of the various values of the fluctuation and the fundamental equation of thermodynamics of any given system, a simple and useful method of calculating the fluctuations is presented. By using the method, the fluctuations of thermodynamic quantities can be directly determined from the fundamental equation of thermodynamics. Finally, some examples are given to illustrate the use of the method. [ABSTRACT FROM AUTHOR]

Presents a study that pointed out that the condition ΔC[subH]=0 can be taken as the criterion of perfect regeneration for a magnetic Ericsson cycle. Regenerative performance of the magnetic Ericsson cycle; Characteristics of the cycle; Comparison between the Ericsson cycle and Carnot coefficient.

Presents a study that focused on the effect of field-dependent heat capacity on refrigeration in magnetic Ericsson cycles. Limitation of the cycle; Comparison of the Ericsson refrigeration cycle with a magnetic Stirling refrigeration cycle; Description of the magnetic Ericsson refrigeration cycle.

It is pointed out that one cannot regard the function E=P-T[sub 2]σ as the best ecological function. The proof of the best ecological function in a recent article is of no significance. Moreover, it is emphasized that the genuine loss power should be considered in the definition of the ecological function. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a study that analyzed the magnetic Ericsson refrigeration cycle of paramagnetic salts. Advantage of magnetic refrigerators; Assessment of the isomagnetic processes used in the study; Comparison between the Ericsson and Stirling refrigeration cycles.

Comments on the ecological optimization criterion for finite-time heat engines. Concept of loss power; Definition of the ecological function E.