Semiempirical models for image electrostatics. I. Bare external charge

2001 ◽  
Vol 114 (5) ◽  
pp. 2062-2066 ◽  
Author(s):  
Vitaly A. Rassolov ◽  
Mark A. Ratner ◽  
John A. Pople
Keyword(s):  
Semiempirical Models ◽  
External Charge

Assessment of Certainty of Ventilation Processes Mathematical Modeling

2015 ◽  
Vol 725-726 ◽  
pp. 1255-1260
Author(s):  
Tamara Daciuk ◽  
Vera Ulyasheva
Keyword(s):  
Mathematical Modeling ◽  
Turbulent Flows ◽  
Turbulence Models ◽  
Field Measurements ◽  
Heat Emission ◽  
Emission Sources ◽  
Wide Range ◽  
Calculation Results ◽  
Definition Of ◽  
Semiempirical Models

Numerical experiment has been successfully used during recent 10-15 years to solve a wide range of thermal and hydrogasodynamic tasks. Application of mathematical modeling used to design the ventilation systems for production premises characterized by heat emission may be considered to be an effective method to obtain reasonable solutions. Results of calculation performed with numerical solution of ventilation tasks depend on turbulence model selection. Currently a large number of different turbulence models used to calculate turbulent flows are known. Testing and definition of applicability limits for semiempirical models of turbulence should be considered to be a preliminary stage of calculation. This article presents results of test calculations pertaining to thermal air process modeling in premises characterized by presence of heat emission sources performed with employment of different models of turbulence. Besides, analysis of calculation results and comparison with field measurements data are presented.

Solubility of the Ketoconazole (an Antifungal Drug) in Supercritical Carbon Dioxide and Menthol as a Cosolvent (Ternary System): Experimental Data and Empirical Correlations

2021 ◽  
Author(s):  
Gholamhossein Sodeifian ◽  
Seyed Ali Sajadian ◽  
Fariba Razmimanesh ◽  
Seyed Mojtaba Hazaveie
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Binary System ◽  
Supercritical Carbon Dioxide ◽  
Ternary System ◽  
Drug Solubility ◽  
Analysis Method ◽  
Empirical Correlations ◽  
Semiempirical Models ◽  
Supercritical Carbon

Abstract One of the main steps in choosing the drug nanoparticle production processes by supercritical carbon dioxide (SC-CO2) is determining the solubility of the solid solute. For this purpose, the solubility of Ketoconazole (KTZ) in the SC-CO2, binary system, as well as in the SC-CO2-menthol (cosolvent), ternary system, was measured at 308–338 K and 12–30 MPa using the static analysis method. The KTZ solubility in the SC-CO2 ranged between 1.70×10− 6 and 8.02×10− 4, while drug solubility in the SC-CO2 with cosolvent varied from 2.7×10− 5 to 1.96×10− 4. This difference indicated the significant effect of menthol cosolvent on KTZ solubility in the SC-CO2. Moreover, KTZ solubilities in the two systems were correlated by several empirical and semiempirical models. Among them, Sodeifian et al., Bian et al., MST, and Bartle et al. models can more accurately correlate experimental data for the binary system than other used models. Also, the Sodeifian and Sajadian model well fitted the solubility data of the ternary system with AARD,%= 6.45, Radj= 0.995.

scholarly journals Soil Moisture Estimate Uncertainties from the Effect of Soil Texture on Dielectric Semiempirical Models

2020 ◽  
Vol 12 (14) ◽  
pp. 2343
Author(s):  
Jing Liu ◽  
Qinhuo Liu
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Texture ◽  
Dielectric Behavior ◽  
Volumetric Water Content ◽  
Frequency Range ◽  
Dielectric Model ◽  
Texture Effect ◽  
Semi Empirical ◽  
Semiempirical Models

Soil texture has been shown to affect the dielectric behavior of soil over the entire frequency range. Three universally employed dielectric semiempirical models (SEMs), the Dobson model, the Wang–Schmugge model and the Mironov model, as well as a new improved SEM known as the soil semi-empirical mineralogy-related-to-water dielectric model (SSMDM), incorporate a significant soil texture effect in different ways. In this paper, soil moisture estimate uncertainties from the effect of soil texture on these four SEMs are systematically and widely investigated over all soil texture cases at different frequencies between 1.4 and 18 GHz for volumetric water content levels between 0.0 and 0.4 m3/m3 from the perspective of two aspects: soil dielectric model discordance and soil texture discordance. Firstly, the effect of soil texture on these four dielectric SEMs is analyzed. Then, soil moisture estimate uncertainties due to the effect of soil texture are carefully investigated. Finally, the applicability of these SEMs is discussed, which can supply references for their choice. The results show that soil moisture estimate uncertainties are small and satisfy the 4% volumetric water content retrieval requirement in some cases. However, in other cases, it may contribute relatively significant uncertainties to soil moisture estimates and correspond to a difference that exceeds the 4% volumetric water content requirement, with potential for the largest deviations to exceed 0.22 m3/m3.

scholarly journals Zonation of Positively Buoyant Jets Interacting with the Water-Free Surface Quantified by Physical and Numerical Modelling

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1324
Author(s):  
Javier García-Alba ◽  
Javier Bárcena ◽  
Andrés García
Keyword(s):  
Free Surface ◽  
Physical Model ◽  
Numerical Models ◽  
Longitudinal Axis ◽  
Laser Induce Fluorescence ◽  
Buoyant Jets ◽  
Physical Tests ◽  
Manipulation Model ◽  
Semiempirical Models ◽  
The Impact

The evolution of positively buoyant jets was studied with non-intrusive techniques—Particle Image Velocimetry (PIV) and Laser Induce Fluorescence (LIF)—by analyzing four physical tests in their four characteristic zones: momentum dominant zone (jet-like), momentum to buoyancy transition zone (jet to plume), buoyancy dominant zone (plume-like), and lateral dispersion dominant zone. Four configurations were tested modifying the momentum and the buoyancy of the effluent through variations of flow discharge and the thermal gradient with the receiving water body, respectively. The physical model results were used to evaluate the performance of numerical models to describe such flows. Furthermore, a new method to delimitate the four characteristic zones of positively buoyant jets interacting with the water-free surface was proposed using the angle (α) shaped by the tangent of the centerline trajectory and the longitudinal axis. Physical model results showed that the dispersion of mass (concentrations) was always greater than the dispersion of energy (velocity) during the evolution of positively buoyant jets. The semiempirical models (CORJET and VISJET) underestimated the trajectory and overestimated the dilution of positively buoyant jets close to the impact zone with the water-free surface. The computational fluid dynamics (CFD) model (Open Field Operation And Manipulation model (OpenFOAM)) is able to reproduce the behavior of positively buoyant jets for all the proposed zones according to the physical results.

Semiempirical models of chromospheric flare regions

1980 ◽  
Vol 242 ◽  
pp. 336 ◽  
Author(s):  
M. E. Machado ◽  
E. H. Avrett ◽  
J. E. Vernazza ◽  
R. W. Noyes
Keyword(s):  
Semiempirical Models ◽  
Chromospheric Flare
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