scholarly journals Possibilities of measuring the local density of seawater in probe instruments

2021 ◽  
pp. 61-67
Author(s):  
V.A. Gaisky ◽  
◽  
P.V. Gaisky ◽  
Keyword(s):  
Equation Of State ◽  
Technological Progress ◽  
Local Density ◽  
Temperature Correction ◽  
Laboratory Measurements ◽  
Rectangular Coordinate System ◽  
Hydrostatic Method ◽  
Direct Measurements ◽  
Technical Solutions ◽  
Account Temperature

In modern expeditionary research carried out on research vessels, the local density of seawater is not measured, but calculated using the TEOS-10 thermodynamic equation of state based on cumulative measurements of pressure, temperature and electrical conductivity or speed of sound. The equation of state with satisfactory accuracy is valid only for oceanological waters, and is used with corrections for the waters of the marginal and inland seas. These corrections are permanently refined and will be refined in the future. It is desirable to have direct measurements of the local density of any waters directly in the environment with sufficient accuracy, which is now 4·10-6. Laboratory measurements made by various methods and with different devices, not always automated, give accuracy ~ . Attempts to automate these measurements and introduce them into sounding devices have been made several times. Experimental samples of vibration, refractometric and hydrostatic devices have been created and tested, none of which have been introduced into the practice of expeditionary work for various reasons. However, scientific and technological progress makes possible technical solutions previously difficult to implement. This also applies to modifications of the hydrostatic method for measuring the local density, which have recently attracted the interest of developers. The paper analyzes the possibilities of implementing the hydrostatic method using multi-element resistor distributed pressure and temperature sensors, resistance profilers of these sensors and determining the spatial pressure drop on a given base by measuring and subtracting sensor resistances, taking into account temperature correction. The use of three such sensors, mounted on three rods, oriented downward along the axes of a rectangular coordinate system, provides the possibility of measuring the local density with an arbitrary orientation of the probe relative to the vertical. The analysis shows the possibility of measuring the local density of seawater by the hydrostatic method with the required accuracy in probe instruments.

Stability of generalized polytropic models

2019 ◽  
Vol 16 (04) ◽  
pp. 1950056
Author(s):  
I. Nazir ◽  
M. Azam
Keyword(s):  
Equation Of State ◽  
Local Density ◽  
Hydrostatic Equilibrium ◽  
Physical Parameters ◽  
Spherically Symmetric ◽  
Anisotropic Matter ◽  
Polytropic Equation ◽  
Density Perturbations ◽  
Radial Forces ◽  
The Stability

In this paper, we have investigated the stability of a spherically symmetric object with charged anisotropic matter by using the concept of cracking. The cracking is a very intuitive technique to check the stability which is based on the analysis of the radial forces that appear on the system due to perturbations taking it out of its equilibrium state. For this, we have applied and studied the effect of local density perturbations to the hydrostatic equilibrium equation and on all the physical parameters with generalized polytropic equation of state. It is found that some of the generalized polytropic models exhibit cracking.

Thermodynamics of Mixing of n-Alkanes with Polyisobutylene

1969 ◽  
Vol 42 (5) ◽  
pp. 1397-1408
Author(s):  
P. J. Flory ◽  
J. L. Ellenson ◽  
B. E. Eichinger
Keyword(s):  
Equation Of State ◽  
Chain Length ◽  
Chemical Potential ◽  
Volume Changes ◽  
Direct Measurements ◽  
Yield Values ◽  
Statistical Mechanical ◽  
Thermodynamics Of Mixing ◽  
Alkane Chain ◽  
Nonpolar Molecules

Abstract The volume changes on mixing polyisobutylene (PIB) with n-pentane, n-hexane, n-heptane, n-octane, n-decane, and n-hexadecane have been determined by direct measurements at 45°, and for n-heptane at 0 and 50° as well. They are negative in every case; the magnitude of the excess volume decreases with chain length, and increases with temperature. These results on volume changes, which are beyond the scope of conventional theories of polymer solutions, are rationally taken into account by the recent statistical mechanical theory of solutions which relates properties of the mixture to characteristics of the pure liquids manifested in their equation-of-state parameters. The negative enthalpies of mixing found by Delmas, Patterson, and Somcynsky for all of these systems with the exception of PIB-n-hexadecane are similarly shown to arise from negative equation-of-state contributions to the enthalpy which reflect differences between the liquid characteristics of n-alkane and PIB. The energy contributed by interchange of neighbor species in contact is shown to be small but positive, as should be expected for the nonpolar molecules involved. It diminishes with chain length of the alkane, becoming little greater than zero in the limit of an infinite alkane chain (polymethylene). Osmotic pressures of concentrated solutions (∼ 15–50%) of PIB in n-octane at 25° yield values of the residual chemical potential, expressed in terms of the conventional parameter χ, which are well reproduced by the theory without arbitrary parameters. The partial molar enthalpy and entropy of dilution are dominated by equation-of-state contributions rendering both of them negative, despite the large positive combinatory entropy. The appearance of critical miscibility at higher temperatures is thus predicted by the theory without resort to special explanations.

scholarly journals Non-equilibrium Equation of State in the Approximation of the Local Density Functional and Its Application to the Emission of High-Energy Particles in Collisions of Heavy Ions

2021 ◽  
Author(s):  
A.T. D’yachenko ◽  
I.A. Mitropolsky
Keyword(s):  
Equation Of State ◽  
Equilibrium Equation ◽  
Heavy Ions ◽  
Density Functional ◽  
Local Density ◽  
Hot Spot ◽  
Ion Collisions ◽  
Hydrodynamic Approach ◽  
Expansion Stage ◽  
Non Equilibrium

The non-equilibrium equation of state is found in the approximation of the functional on the local density, and its application to the description of the emission of protons and pions in heavy ion collisions is considered. The non-equilibrium equation of state is studied in the context of the hydrodynamic approach. The compression stage, the expansion stage, and the freeze-out stage of the hot spot formed during the collisions of heavy ions are considered. The energy spectra of protons and subthreshold pions produced in collisions of heavy ions are calculated with inclusion of the nuclear viscosity effects and compared with experimental data for various combinations of colliding nuclei with energies of several tens of MeV per nucleon.

scholarly journals Mechanical Calculation of Flexible Wires of Spans with Different Tensioning Insulator Strings

2020 ◽  
Vol 63 (1) ◽  
pp. 55-65 ◽  
Author(s):  
Yu. V. Bladyko
Keyword(s):  
Equation Of State ◽  
Horizontal Wind ◽  
Load Factor ◽  
Inclined Plane ◽  
Load Factors ◽  
Design Activities ◽  
Ice Loads ◽  
The Wire ◽  
The Difference ◽  
Technical Solutions

In design activities, technical solutions are practiced, which provide for the use of different tension strings of insulators in a single span. The present paper considers the calculation of the sag and load factors for a span with two different tensioning insulator strings that are of identical suspension heights. The system of “the first tension insulators string – the wire – the second tension insulators string” was described by the equations of a parabola. A relationship has been established between the sag increase factor and the coefficients that take into account the presence of tensioning insulators strings. The resulting compact formula for sag increase is generally suitable for any combination of strings in a span. The coincidence of the calculation is shown for particular cases known from the literature. The formula for calculating the load factor for the equation of state was derived, taking into account the presence of different strings in the span. The reliability of the formula has been proved by the coincidence of results for particular cases of the arrangement of strings. The obtained expressions can be used both for vertical (weight and ice) loads and for horizontal (wind) ones. In the case of loads in two planes, the equation of state must take into account all the components when calculating the resulting reduced load on the wire along the inclined plane. Calculations were performed for different lengths of spans of switchgear with different wires and strings of insulators. A span with one and two tensioning strings of insulators, with the same suspension heights, in the absence of wind and ice is considered. The curves of the sagging wires to different strings have been plotted. It is demonstrated that when calculating sags and tensions, the difference between strings must not be neglected.

scholarly journals COMBINATION OF THE ISOCHORIC METHOD AND THE EXPANSION METHOD TO DETERMINE DENSITIES OF HYDROGEN AT TEMPERATURES UP TO 500°C

SINERGI ◽  
2018 ◽  
Vol 22 (2) ◽  
pp. 107
Author(s):  
Supriatno Supriatno
Keyword(s):  
Equation Of State ◽  
Measurement Method ◽  
Expansion Method ◽  
Maximum Deviation ◽  
Low Density ◽  
Pvt Properties ◽  
Present Measurement ◽  
Direct Measurements ◽  
Temperature And Pressure ◽  
Gas Volume

Utilization of hydrogen as an alternative fuel is promising because it is environmentally friendly. Hydrogen system design requires accurate hydrogen densities. The density of hydrogen is determined based on experimental data. For gases that have a low density such as hydrogen, the effective measurement method is required. An apparatus has been designed to measure PVT properties of hydrogen at pressures up to 1 MPa and temperatures up to 500ºC. The apparatus uses a combination of isochoric and expansion methods. The method doesn’t need a measurement of pressures and temperatures along the isochoric line as required usually in the isochoric conventional method. Moreover, it doesn't need direct measurements of gas mass and gas volume. The volume was determined by measuring nitrogen at a pressure of 0.5 MPa and at temperatures up to 500ºC and by using Span’s equation of state. Measurements of hydrogen have been performed at a pressure up to 0.7 MPa and temperatures up to 498.217ºC. Densities of hydrogen obtained from the present measurement are compared with that obtained from calculation of Leachman's equation of state. Maximum deviation is 1.42% at a temperature of 498.217ºC and at a pressure of 0.2947 MPa and minimum deviation is 0.11% at temperature and pressure of 399.461ºC and 0.6981 MPa respectively.

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