scholarly journals Supercritical behavior of thermodynamic systems

2019 ◽  
Vol 27 (1) ◽  
pp. 19-26
Author(s):  
A. N. Galdina
Keyword(s):  
Phase Transitions ◽  
Phase Equilibrium ◽  
Limit Point ◽  
Thermodynamic System ◽  
Continuous Phase ◽  
Stability Conditions ◽  
Equilibrium Curve ◽  
Limit Case ◽  
Phase Equilibrium Curve ◽  
Thermodynamic Forces

It is known that basic stability characteristics of a system are inversely proportional to fluctuations of external parameters. Above the critical point there is a region remaining homogeneous macroscopically, but becoming microheterogeneous within an interval of thermodynamic forces. Within this interval thermodynamic coefficients of stability pass finite non-zero minima. This corresponds to the considerable growth of fluctuations and indicates the occurrence of supercritical transition of continuous kind. The limit case of such continuous phase transitions is the critical state, which is also the limit point of some first-kind transitions (the limit point of phase equilibrium curve).In this paper we consider the relation between thermodynamic stability conditions and fluctuations of external parameters of the system. We study the behavior of a simple one-component thermodynamic system (liquid, magnet, and ferroelectric) in the supercritical region and derive the equation of the line of supercritical transition for this system.

scholarly journals Empirical evidence reveals the phase diagram of patch patterns in Mediterranean drylands

2017 ◽  
Author(s):  
Fernando Meloni ◽  
Cristiano R. F. Granzotti ◽  
Alexandre S. Martinez
Keyword(s):  
Phase Diagram ◽  
Phase Transitions ◽  
Satellite Images ◽  
A Priori ◽  
Continuous Phase ◽  
Adequate Description ◽  
Scaling Exponents ◽  
Open Issue ◽  
The Subject ◽  
Ecological Functioning

AbstractDrylands are ecosystems with limited water resources, often subjected to desertification. Conservation and restoration efforts towards these ecosystems depend on the interplay between ecological functioning and spatial patterns formed by local vegetation. Despite recent advances on the subject, an adequate description of phase transitions between the various vegetated phases remains an open issue. Here, we gather vegetation data of drylands from Southern Spain using satellite images. Our findings support three vegetated phases, separated by two distinct phase transitions, including a continuous phase transition, with new relations between scaling exponents of ecological variables. The phase diagram is obtained without a priori assumption about underlying ecological dynamics. We apply our analysis to a different dryland system in the Western United States and verify a compatible critical behavior, in agreement with the universality hypothesis.

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