scholarly journals Analytical Determination of the Nucleation-Prone, Low-Density Fraction of Subcooled Water

Entropy ◽  
2020 ◽  
Vol 22 (9) ◽  
pp. 933
Author(s):  
Olaf Hellmuth ◽  
Rainer Feistel
Keyword(s):  
Equation Of State ◽  
Accurate Determination ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Analytical Determination ◽  
Thermodynamic Quantities ◽  
Low Density ◽  
Water Fraction ◽  
Subcooled Water

Subcooled water is the primordial matrix for ice embryo formation by homogeneous and heterogeneous nucleation. The knowledge of the specific Gibbs free energy and other thermodynamic quantities of subcooled water is one of the basic prerequisites of the theoretical analysis of ice crystallization in terms of classical nucleation theory. The most advanced equation of state of subcooled water is the IAPWS G12-15 formulation. The determination of the thermodynamic quantities of subcooled water on the basis of this equation of state requires the iterative determination of the fraction of low-density water in the two-state mixture of low-density and high-density subcooled water from a transcendental equation. For applications such as microscopic nucleation simulation models requiring highly frequent calls of the IAPWS G12-15 calculus, a new two-step predictor-corrector method for the approximative determination of the low-density water fraction has been developed. The new solution method allows a sufficiently accurate determination of the specific Gibbs energy and of all other thermodynamic quantities of subcooled water at given pressure and temperature, such as specific volume and mass density, specific entropy, isothermal compressibility, thermal expansion coefficient, specific isobaric and isochoric heat capacities, and speed of sound. The misfit of this new approximate analytical solution against the exact numerical solution was demonstrated to be smaller than or equal to the misprediction of the original IAPWS G12-15 formulation with respect to experimental values.

scholarly journals Recent progress on the accurate determination of the equation of state of neutron and nuclear matter

2011 ◽  
Vol 336 ◽  
pp. 012014 ◽  
Author(s):  
Paolo Armani ◽  
Alexey Yu Illarionov ◽  
Diego Lonardoni ◽  
Francesco Pederiva ◽  
Stefano Gandolfi ◽  
...  
Keyword(s):  
Equation Of State ◽  
Nuclear Matter ◽  
Recent Progress ◽  
Accurate Determination

scholarly journals Equation of State of Warm Condensed Matter

1997 ◽  
Vol 499 ◽  
Author(s):  
T. W. Barbee ◽  
D. A. Young ◽  
F. J. Rogers
Keyword(s):  
Equation Of State ◽  
Finite Temperature ◽  
Condensed Matter ◽  
Accurate Determination ◽  
Temperature Limit ◽  
High Temperature Limit ◽  
Condensed Matter Theory ◽  
Matter Theory ◽  
Properties Of Materials

ABSTRACTRecent advances in computational condensed matter theory have yielded accurate calculations of properties of materials. These calculations have, for the most part, focused on the low temperature (T=0) limit. An accurate determination of the equation of state (EOS) at finite temperature also requires knowledge of the behavior of the electron and ion thermal pressure as a function of T. Current approaches often interpolate between calculated T=0 results and approximations valid in the high T limit. Plasma physics-based approaches are accurate in the high temperature limit, but lose accuracy below T∼Tfermi. We seek to “connect up” these two regimes by using ab initio finite temperature methods (including linear-response[l] based phonon calculations) to derive an equation of state of condensed matter for T<Tfermi.We will present theoretical results for the principal Hugoniot of shocked materials, including carbon and aluminum, up to pressures P>100 GPa and temperatures T> 104K, and compare our results with available experimental data.

scholarly journals CONCERNING THE EQUATION OF STATE FOR A PARTIALLY IONIZED SYSTEM

2009 ◽  
Vol 23 (20n21) ◽  
pp. 3968-3978
Author(s):  
GEORGE A. BAKER
Keyword(s):  
Equation Of State ◽  
Ideal Gas ◽  
Thermodynamic Quantities ◽  
Low Density ◽  
Cellular Model ◽  
Density Region ◽  
Cellular Models ◽  
Maxwell Construction ◽  
Actual Region ◽  
The Ideal

I will discuss the expansion of various thermodynamic quantities about the ideal gas in powers of the electric charge, and I will discuss some cellular models. The first type of cellular model is appropriate for hydrogen. The second type is for Z > 1. It has the independent electron approximation within the atoms. These models are cross compared and minimal regions of validity are determined. The actual region of validity is expected to be larger. In the cellular models, the phase boundaries for liquid-gas transitions are found. For the second type of cellular model, in the part of the low-temperature, low-density region where there is not much expectation of validity of these methods, a non-thermodynamic region is found. I have devised a construction, similar in spirit to the Maxwell construction, to bridge this region so as to leave a thermodynamically valid equation of state. The non-thermodynamic region does not occur in hydrogen and it seems to be due to the inadequacy of the aforementioned approximation in that region.

scholarly journals Analytical Determination of the Slot and the End-Winding Portion of the Winding-to-Rotor Capacitance for the Prediction of Shaft Voltage in Electrical Machines

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 174
Author(s):  
Jan Ole Stockbrügger ◽  
Bernd Ponick
Keyword(s):  
Accurate Determination ◽  
Dielectric Strength ◽  
Simulation Method ◽  
Capacitive Coupling ◽  
Analytical Determination ◽  
Single Digit ◽  
Common Mode ◽  
Lubrication Film ◽  
Common Mode Voltage

Common-mode voltage, caused by a 2-level inverter, is a source of discharge currents in motor bearings. Due to the capacitive coupling, between the stator winding and the rotor, an image of the common-mode voltage is produced on the shaft—which can exceed the dielectric strength of the lubrication film of motor bearings. Accurate determination of the winding-to-rotor capacitance is necessary to predict the shaft voltage. This article proposes a novel analytical determination of the slot and the end-winding portion of the winding-to-rotor capacitance. The calculation rules, which are based on the method of image charges and the charge simulation method, take into account the continuity and the boundary conditions of the field areas. Results are validated by means of finite element method simulations. Notably, deviations are in the single-digit percentage range. Furthermore, the presented methods are simple to implement.

scholarly journals A Friendly Complexing Agent for Spectrophotometric Determination of Total Iron

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3071
Author(s):  
Valeria M. Nurchi ◽  
Rosita Cappai ◽  
Nadia Spano ◽  
Gavino Sanna
Keyword(s):  
Accurate Determination ◽  
Iron Concentration ◽  
Total Iron ◽  
Analytical Determination ◽  
Complexing Agent ◽  
Industrial Chemistry ◽  
Spectrophotometric Methods ◽  
Desferrioxamine B ◽  
Control Serum

Iron, one of the most common metals in the environment, plays a fundamental role in many biological as well as biogeochemical processes, which determine its availability in different oxidation states. Its relevance in environmental and industrial chemistry, human physiology, and many other fields has made it necessary to develop and optimize analysis techniques for accurate determination. Spectrophotometric methods are the most frequently applied in the analytical determination of iron in real samples. Taking advantage of the fact that desferrioxamine B, a trihydroxamic acid used since the 1970s in chelation therapy for iron overload treatment, forms a single stable 1:1 complex with iron in whichever oxidation state it can be found, a smart spectrophotometric method for the analytical determination of iron concentration was developed. In particular, the full compliance with the Lambert-Beer law, the range of iron concentration, the influence of pH, and the interference of other metal ions have been taken into account. The proposed method was validated in terms of LoD, LoQ, linearity, precision, and trueness, and has been applied for total iron determination in natural water certified material and in biological reference materials such as control human urine and control serum.

Effect of plasma triglyceride concentrations on the accuracy of immunoturbidimetric assays of apolipoprotein B

1991 ◽  
Vol 37 (5) ◽  
pp. 748-753 ◽  
Author(s):  
T A Walmsley ◽  
S Grant ◽  
P M George
Keyword(s):  
Apolipoprotein B ◽  
Accurate Determination ◽  
Low Density Lipoproteins ◽  
Plasma Triglyceride ◽  
Relative Reactivity ◽  
Tween 20 ◽  
Low Density ◽  
Very Low Density Lipoproteins ◽  
Normal Triglyceride

Abstract We have studied the influence of triglyceride-rich particles on the analytical bias of apolipoprotein B measurements by various immunoturbidimetric methods. Three commercially available methods grossly overestimate apolipoprotein B in samples with even moderately above-normal triglyceride concentrations. This effect is due to the increased relative reactivity of very-low-density lipoproteins in these reagent systems, and can be eliminated by including Tween 20 (2 g/L) in the reagent buffer. We have developed, and describe, an automated immunoturbidimetric method that allows the accurate determination of apolipoprotein B in the plasma of patients with hypertriglyceridemia.

scholarly journals Roles of crust and core in the tidal deformability of neutron stars

2019 ◽  
Vol 28 (09) ◽  
pp. 1950081 ◽  
Author(s):  
A. M. Kalaitzis ◽  
T. F. Motta ◽  
A. W. Thomas
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Dense Matter ◽  
Moment Of Inertia ◽  
Recent Measurement ◽  
Low Density ◽  
Important Constraint ◽  
The Moment

With the recent measurement of GW170817 providing constraints on the tidal deformability (TD) of a neutron star, it is very important to understand what features of the equation of state (EoS) have the biggest effect on it. We therefore study the contribution of the crust to the TD and the moment of inertia (MoI) of a neutron star for a variety of well-known EoS. It is found that the contributions to these quantities from the low-density crust are typically quite small and as a result the determination of the TD provides an important constraint on the EoS of dense matter.

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