scholarly journals The diffusion of radon gas mixtures

1939 ◽  
Vol 169 (939) ◽  
pp. 573-586 ◽  
Keyword(s):  
Thermal Diffusion ◽  
Special Theory ◽  
Gas Mixtures ◽  
Repulsive Force ◽  
Wide Range ◽  
Experimental Values ◽  
Coefficient Of Viscosity ◽  
The Given ◽  
Helium Neon ◽  
Coefficient Of Diffusion

The repulsive force, F 12 , between dissimilar molecules may be represented by the equation F 12 = μ 12 d - 8 12, where d is the distance between the dissimilar molecules which are regarded as point centres of repulsive force, while 8 12 represents the repulsive force index, and μ 12 the repulsive force constant between these molecules. Chapman (1929) has given a special theory of thermal diffusion in mixtures of two gases in which one component is rare and heavy. He has shown that F 12 may be determined provided that thermal diffusion measurements for the given gas mixture have been made, and the coefficient of viscosity of the lighter gas at various temperatures together with the coefficient of diffusion of the two gases is known. Thermal diffusion measurements for radon-hydrogen and radon-helium gas mixtures have already been made by one of us (Harrison 1937), radon being the rare and heavy constituent of these mixtures. The variation of the viscosity of hydrogen and helium over a wide range of temperature was known, but no experimental value of the coefficient of diffusion of radon into hydrogen or helium was available. In the previous investigation, approximate values of the latter were therefore calculated from a formula given by Chapman (1917). Owing to uncertainty in the accuracy of these calculated values, 8 12 was evaluated approximately for radon-hydrogen and radon-helium molecules, but μ 12 was not calculated, since the latter is much more sensitive to an error in the coefficient of diffusion than the former. The purpose of the present investigation was to obtain experimental values of the coefficient of diffusion of radon into hydrogen, helium, neon and argon, so that the repulsive force between radon-hydrogen and radonhelium molecules can be derived from existing experimental evidence, and that for radon-neon and radon-argon can be obtained when the thermal diffusion measurements for these two mixtures are completed. Information concerning the very massive, monatomic radon molecule obtained from diffusion experiments is of special interest, particularly as the molecular field cannot be obtained from viscosity measurements or the equation of state owing to the extremely small quantity of gas available.

scholarly journals The thermal diffusion of radon gas mixtures

1937 ◽  
Vol 161 (904) ◽  
pp. 80-94 ◽  
Keyword(s):  
Thermal Diffusion ◽  
Simple Form ◽  
Large Change ◽  
Gas Mixtures ◽  
Repulsive Force ◽  
Theoretical Treatment ◽  
Radon Gas ◽  
Coefficient Of Viscosity ◽  
The Relationship

A special theoretical treatment of thermal diffusion in mixtures of two gases, in which one component is rare, has been given by Chapman (1929). An interesting result which emerges from this theory is that this phenomenon may produce a large change in the quantity of the rare constituent on the cold and hot sides. Let M 1 be the mass of the molecules of the rare and heavy constituent, M 2 that of the light constituent, and r the ratio of the proportion by volume of the rare constituent on the cold to that on the hot side, after thermal diffusion. When M 2 / M 1 is small, the formulae expressing the relationship between r and s 12 , the repulsive force index between unlike molecules, can be expressed in a simple form. In this case, the experimental value of the ratio, r , together with the coefficient of ordinary diffusion of the two gases and the coefficient of viscosity of the lighter gas, suffices to determine s 12 .

scholarly journals The thermal diffusion of radon gas mixtures

1942 ◽  
Vol 181 (984) ◽  
pp. 93-100 ◽  
Keyword(s):  
Force Field ◽  
Thermal Diffusion ◽  
Special Theory ◽  
Mean Value ◽  
Repulsive Force ◽  
Inert Gases ◽  
Inert Gas ◽  
Cold Side ◽  
The Mean ◽  
Gas Molecules

In continuation of earlier experiments (Harrison 1937) in which the thermal diffusion in radon-hydrogen and radon-helium mixtures was measured, the thermal diffusion of mixtures of radon-neon and radon-argon has now been studied. The mean value obtained for the ratio of the proportion by volume of radon on the cold side at 0° C to that on the hot side at 100° C, after thermal diffusion, was 1·074 for radon-neon mixtures, and 1·008 for radon-argon mixtures. In order to calculate the repulsive force field, F 12 , between these two pairs of molecules, the present results were combined with measurements of ordinary diffiisirm of radon into neon and radon into argon (Hirst & Harrison 1939), and viscosity determinations at various temperatures of neon and argon (Trautz & Binkele 1930). The special theory, due to Chapman (1929), of thermal diffusion of a rare constituent in a binary mixture was used to derive Flt. The values obtained for the repulsive force field between the dissimilar molecules at collision were: F 12 (radon-neon) = 1·9 x 10 -51 d -6·1 = ( d / d 0 ) -6·1 , d 0 = 4·8 x 10 -9 , F 12 (radon-argon) = 2·1 x 10 -43 d -5·1 = ( d 0 )-5·1 , d 0 = 4·3 x 10 -9 , d being the distance between the point centres of repulsive force and d 0 the value of d at which F 12 is 1 dyne. A comparison of the values obtained for the repulsive force index for radon-neon and radon-argon molecules with those obtained by Atkins, Bastick & Ibbs (1939) for binary mixtures of the first five inert gases shows that radon is the4 softest ’ of the inert gas molecules. Radon-argon molecules are the closest approach to the Maxwellian case yet studied experimentally.

The thermal diffusion factor and temperature

1954 ◽  
Vol 224 (1159) ◽  
pp. 513-526 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Thermal Diffusion ◽  
Gas Mixtures ◽  
Diffusion Factor ◽  
Thermal Diffusion Factor ◽  
Lennard Jones ◽  
Hydrogen Deuterium ◽  
Experimental Values

The thermal diffusion factor has been measured for several gas mixtures in a range of temperature which included that at which the reversal of sign, predicted theoretically when a Lennard-Jones type of interaction is assumed, might be observed. A reversal was found with hydrogen-deuterium, nitrogen-argon, oxygen-argon and nitrogen-carbon dioxide mixtures; with neon-argon, argon-krypton and krypton-xenon mixtures no reversal was observed, the thermal diffusion factor having a small positive value at the lowest tempera­tures at which measurements could be made. A comparison of the experimental values of the thermal diffusion factor with values calculated for the Lennard-Jones (13, 7) model shows that this model is not quantitatively satisfactory.

scholarly journals Measurement of Electron Impact Ionisation and Attachment Coefficients in NO2/He Gas Mixtures and Estimated Electron Collision Cross Sections for NO2

1995 ◽  
Vol 48 (3) ◽  
pp. 419 ◽  
Author(s):  
Y Sakai ◽  
T Okumura ◽  
H Tagashira
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Gas Mixtures ◽  
Electron Collision ◽  
Boltzmann Equation Analysis ◽  
Equation Analysis ◽  
Wide Range ◽  
Impact Ionisation ◽  
The Cross ◽  
Experimental Values

The electron impact ionisation a/po and attachment coefficients r]/po in N02/He gas mixtures, where po is the gas pressure at O�C, are measured by a steady-state Townsend method over a wide range of compositions and E/po values. Based on the experimental values of a/po and r]/ po, a preliminary set of the cross sections for N02 is estimated by a Boltzmann equation analysis and values of the cross sections are discussed.

scholarly journals DFT calculation and assignment of vibrational spectra of aryl and alkyl chlorophosphates

2014 ◽  
Vol 12 (2) ◽  
pp. 153-163
Author(s):  
Viktor Anishchenko ◽  
Vladimir Rybachenko ◽  
Konstantin Chotiy ◽  
Andrey Redko
Keyword(s):  
Vibrational Spectra ◽  
Basis Sets ◽  
Heavy Atoms ◽  
Wide Range ◽  
Complete Assignment ◽  
Key Factor ◽  
Polarization Functions ◽  
Experimental Values ◽  
Semi Empirical ◽  
Good Agreement

AbstractDFT calculations of vibrational spectra of chlorophosphates using wide range of basis sets and hybrid functionals were performed. Good agreement between calculated and experimental vibrational spectra was reached by the combination of non-empirical functional PBE0 with both middle and large basis sets. The frequencies of the stretching vibrations of the phosphate group calculated using semi-empirical functional B3LYP for all basis sets deviate significantly from the experimental values. The number of polarization functions on heavy atoms was shown to be a key factor for the calculation of vibrational frequencies of organophosphates. The importance of consideration of all the stable rotamers for a complete assignment of fundamental modes was shown.

scholarly journals Optimising the AR Engraved Structure on Light-Guide Facets for a Wide Range of Wavelengths

Optics ◽  
2020 ◽  
Vol 2 (1) ◽  
pp. 25-42
Author(s):  
Ioseph Gurwich ◽  
Yakov Greenberg ◽  
Kobi Harush ◽  
Yarden Tzabari
Keyword(s):  
Theoretical Analysis ◽  
Light Guide ◽  
Spectral Band ◽  
Angular Range ◽  
The Past ◽  
Input And Output ◽  
Wide Range ◽  
The Given ◽  
Theoretical Results ◽  
Shape And Size

The present study is aimed at designing anti-reflective (AR) engraving on the input–output surfaces of a rectangular light-guide. We estimate AR efficiency, by the transmittance level in the angular range, determined by the light-guide. Using nano-engraving, we achieve a uniform high transmission over a wide range of wavelengths. In the past, we used smoothed conical pins or indentations on the faces of light-guide crystal as the engraved structure. Here, we widen the class of pins under consideration, following the physical model developed in the previous paper. We analyze the smoothed pyramidal pins with different base shapes. The possible effect of randomization of the pins parameters is also examined. The results obtained demonstrate optimized engraved structure with parameters depending on the required spectral range and facet format. The predicted level of transmittance is close to 99%, and its flatness (estimated by the standard deviation) in the required wavelengths range is 0.2%. The theoretical analysis and numerical calculations indicate that the obtained results demonstrate the best transmission (reflection) we can expect for a facet with the given shape and size for the required spectral band. The approach is equally useful for any other form and of the facet. We also discuss a simple way of comparing experimental and theoretical results for a light-guide with the designed input and output features. In this study, as well as in our previous work, we restrict ourselves to rectangular facets. We also consider the limitations on maximal transmission produced by the size and shape of the light-guide facets. The theoretical analysis is performed for an infinite structure and serves as an upper bound on the transmittance for smaller-size apertures.

scholarly journals Towards an accurate description of perovskite ferroelectrics: exchange and correlation effects

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Simuck F. Yuk ◽  
Krishna Chaitanya Pitike ◽  
Serge M. Nakhmanson ◽  
Markus Eisenbach ◽  
Ying Wai Li ◽  
...  
Keyword(s):  
Density Functional ◽  
General Purpose ◽  
Correlation Effects ◽  
Lattice Constants ◽  
Bulk Solids ◽  
Wide Range ◽  
Exchange Enhancement ◽  
Experimental Values ◽  
Similar Accuracy ◽  
Ferroelectric Oxides

Abstract Using the van der Waals density functional with C09 exchange (vdW-DF-C09), which has been applied to describing a wide range of dispersion-bound systems, we explore the physical properties of prototypical ABO 3 bulk ferroelectric oxides. Surprisingly, vdW-DF-C09 provides a superior description of experimental values for lattice constants, polarization and bulk moduli, exhibiting similar accuracy to the modified Perdew-Burke-Erzenhoff functional which was designed specifically for bulk solids (PBEsol). The relative performance of vdW-DF-C09 is strongly linked to the form of the exchange enhancement factor which, like PBEsol, tends to behave like the gradient expansion approximation for small reduced gradients. These results suggest the general-purpose nature of the class of vdW-DF functionals, with particular consequences for predicting material functionality across dense and sparse matter regimes.

Study of Temperature Effect on Servovalve-Controlled Fuel Metering Unit

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Bin Wang ◽  
Haocen Zhao ◽  
Ling Yu ◽  
Zhifeng Ye
Keyword(s):  
Steady State ◽  
Temperature Variation ◽  
Dynamic Characteristics ◽  
Numerical Study ◽  
Step Response ◽  
Fuel Temperature ◽  
Wide Range ◽  
Fuel Rate ◽  
Testing Condition ◽  
The Given

It is usual that fuel system of an aero-engine operates within a wide range of temperatures. As a result, this can have effect on both the characteristics and precision of fuel metering unit (FMU), even on the performance and safety of the whole engine. This paper provides theoretical analysis of the effect that fluctuation of fuel temperature has on the controllability of FMU and clarifies the drawbacks of the pure mathematical models considering fuel temperature variation for FMU. Taking the electrohydraulic servovalve-controlled FMU as the numerical study, simulation in AMESim is carried out by thermal hydraulic model under the temperatures ranged from −10 to 60 °C to confirm the effectiveness and precision of the model on the basis of steady-state and dynamic characteristics of FMU. Meanwhile, the FMU testing workbench with temperature adjustment device employing the fuel cooler and heater is established to conduct an experiment of the fuel temperature characteristics. Results show that the experiment matches well with the simulation with a relative error no more than 5% and that 0–50 °C fuel temperature variation produces up to 5.2% decrease in fuel rate. In addition, step response increases with the fuel temperature. Fuel temperature has no virtual impact on the steady-state and dynamic characteristics of FMU under the testing condition in this paper, implying that FMU can operate normally in the given temperature range.

scholarly journals Thermal Conductivities of Choline Chloride-Based Deep Eutectic Solvents and Their Mixtures with Water: Measurement and Estimation

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3816
Author(s):  
Taleb H. Ibrahim ◽  
Muhammad A. Sabri ◽  
Nabil Abdel Jabbar ◽  
Paul Nancarrow ◽  
Farouq S. Mjalli ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Choline Chloride ◽  
Deep Eutectic Solvents ◽  
Standard Uncertainty ◽  
Heat Transfer Fluids ◽  
Wide Range ◽  
Different Temperatures ◽  
Experimental Values ◽  
Water Measurement ◽  
Thermal Conductivities

The thermal conductivities of selected deep eutectic solvents (DESs) were determined using the modified transient plane source (MTPS) method over the temperature range from 295 K to 363 K at atmospheric pressure. The results were found to range from 0.198 W·m−1·K−1 to 0.250 W·m−1·K−1. Various empirical and thermodynamic correlations present in literature, including the group contribution method and mixing correlations, were used to model the thermal conductivities of these DES at different temperatures. The predictions of these correlations were compared and consolidated with the reported experimental values. In addition, the thermal conductivities of DES mixtures with water over a wide range of compositions at 298 K and atmospheric pressure were measured. The standard uncertainty in thermal conductivity was estimated to be less than ± 0.001 W·m−1·K−1 and ± 0.05 K in temperature. The results indicated that DES have significant potential for use as heat transfer fluids.

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