Potentiostatic study of ferrous–ferric kinetics at bright gold and platinum electrodes

1969 ◽  
Vol 47 (10) ◽  
pp. 1661-1666 ◽  
Author(s):  
Sidney Barnartt
Keyword(s):  
Activity Coefficient ◽  
Reaction Kinetics ◽  
Current Density ◽  
Sulfate Solution ◽  
Platinum Electrodes ◽  
Ionic Activity ◽  
Potential Control ◽  
Sulfate Solutions ◽  
Order Of Magnitude ◽  
The Mean

Ferrous–ferric reaction kinetics on gold in chloride and sulfate solutions, and on platinum in a sulfate solution, were studied potentiostatically. The data illustrate the importance of precise potential control and of automatic ohmic compensation. The standard exchange current density is 0.38/f A cm−2 (where f is the mean ionic activity coefficient) on platinum; it is an order of magnitude larger on gold.

Degrees of Dissociation and Hydration Numbers of Twenty Six Strong Electrolytes in Aqueous Solutions at 25 °C

1992 ◽  
Vol 57 (11) ◽  
pp. 2209-2214 ◽  
Author(s):  
Rajalakshmi Heyrovská
Keyword(s):  
Activity Coefficient ◽  
Aqueous Solutions ◽  
Osmotic Coefficients ◽  
Hydration Numbers ◽  
Ionic Activity ◽  
Strong Electrolytes ◽  
The Mean ◽  
First Time ◽  
Degrees Of Dissociation

This paper brings further results on the degrees of dissociation (α) and hydration numbers (nh) of strong electrolytes in aqueous solutions at 25 °C, evaluated for the first time from osmotic coefficients (ϕ). Presented here are also the equations for the non-ideality parameters, ϕ and γ± (the mean molal ionic activity coefficient), in terms of α and nh.

scholarly journals Relaxation Times in Strictly Disk Systems

1971 ◽  
Vol 10 ◽  
pp. 15-19
Author(s):  
George B. Rybicki
Keyword(s):  
Numerical Experiments ◽  
Relaxation Times ◽  
Galactic Structure ◽  
Large Numbers ◽  
Order Of Magnitude ◽  
Vlasov Limit ◽  
The Mean ◽  
Gravitating Systems

AbstractIt is shown that the time of relaxation by particle encounters of self-gravitating systems in the plane interacting by 1/r2 forces is of the same order of magnitude as the mean orbit time. Therefore such a system does not have a Vlasov limit for large numbers of particles, unless appeal is made to some non-zero thickness of the disk. The relevance of this result to numerical experiments on galactic structure is discussed.

scholarly journals Using the SWEPT Methodology for a Preliminary Wind Potential Estimation

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Jean-Luc Menet
Keyword(s):  
Wind Turbine ◽  
Characteristic Curve ◽  
Rayleigh Distribution ◽  
Mean Velocity ◽  
Technical Data ◽  
Wind Potential ◽  
Order Of Magnitude ◽  
General Data ◽  
The Mean ◽  
A Site

The implantation of wind turbines generally follows a wind potential study which is made using specific numerical tools; the generated expenses are only acceptable for great projects. The purpose of the present paper is to propose a simplified methodology for the evaluation of the wind potential, following three successive steps for the determination of (i) the mean velocity, either directly or by the use of the most occurrence velocity (MOV); (ii) the velocity distribution coming from the single knowledge of the mean velocity by the use of a Rayleigh distribution and a Davenport-Harris law; (iii) an appropriate approximation of the characteristic curve of the turbine, coming from only two technical data. These last two steps allow calculating directly the electric delivered energy for the considered wind turbine. This methodology, called the SWEPT approach, can be easily implemented in a single worksheet. The results returned by the SWEPT tool are of the same order of magnitude than those given by the classical commercial tools. Moreover, everybody, even a “neophyte,” can use this methodology to obtain a first estimation of the wind potential of a site considering a given wind turbine, on the basis of very few general data.

Infrared spectra, rotational correlation functions, and intermolecular mean squared torques in compressed gaseous methane

1968 ◽  
Vol 46 (11) ◽  
pp. 1331-1340 ◽  
Author(s):  
R. L. Armstrong ◽  
S. M. Blumenfeld ◽  
C. G. Gray
Keyword(s):  
Correlation Functions ◽  
Theoretical Calculations ◽  
Dominant Contribution ◽  
Dispersion Interactions ◽  
Fundamental Vibration ◽  
Order Of Magnitude ◽  
The Mean ◽  
Vibration Rotation ◽  
Experimental Values ◽  
Rotational Correlation

Extensive measurements of the methane ν3 and ν4 fundamental vibration–rotation bands in CH4–He mixtures and the ν3 band in CH4–He, CH4–N2, and CD4–He mixtures have been carried out in infrared absorption at 295 °K to pressures of 3000 atm. Some profiles of the ν3 band in CH4–Ar mixtures and in pure CH4 have also been obtained. Rotational correlation functions, band moments, and intermolecular mean squared torques have been determined from the ν3 band profiles. Theoretical calculations of the mean squared torque due to anisotropic multipolar, induction and dispersion interactions have been carried out. The theoretical and experimental torques are in order-of-magnitude agreement for the CH4–N2 and CH4–CH4 systems; for CH4–He, CD4–He, and CH4–Ar the theoretical values are two to three orders of magnitude too small to account for the experimental values, indicating that in these cases the dominant contribution to the torques is given by the anisotropic overlap forces.

Simulations on Expansive Strain of Concrete Caused by Ettringite Growth under Sulfate Attack

2011 ◽  
Vol 250-253 ◽  
pp. 1906-1911 ◽  
Author(s):  
Xiao Bao Zuo ◽  
Wei Sun
Keyword(s):  
Sulfate Solution ◽  
Sulfate Attack ◽  
Diffusion Time ◽  
Diffusion Reaction ◽  
Sulfate Ion ◽  
Reaction Equation ◽  
Ettringite Formation ◽  
Sulfate Solutions ◽  
Calcium Aluminates ◽  
Strain Responses

In order to assess theoretically the expansive strain of concrete caused by the ettringite formation and growth under the sulfate attack, some models are proposed to investigate the strain responses of concrete exposed to the sulfate solutions. Firstly, an 1-D nonlinear and nonsteady diffusion-reaction equation of sulfate ion in concrete is proposed; Secondly, based on chemical reactions between sulfate and aluminates in concrete, the expansive strain is obtained due to the ettringite growth resulting in concrete expansion. Thirdly, numerical simulations are carried out to analyze the formation process of the concrete expansive strain under the sulfate solution, and results show that the models can be used to predict the concrete responses with the diffusion time, such as the distribution concentration of sulfate ion, dissipated concentration of the calcium aluminates, expansion strain of concrete due to the formation and growth of ettringite.

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