Electrical conductivity calculation

The values of measured molar conductivities can also be employed for checking the results of the chemical analysis of waters with pH ranging from 6 to 9 (concentration of ions H" and 0H is very low, therefore, the determination cannot be influenced by their mobility). The concentrations of ions determined by analysis are multiplied by the values of mole conductivities at the given temperature and dilution. If electric conductivity calculated in this way lies within 2% of the experimentally determined one, the results of the analysis are considered to be in good agreement. 

These parameters can be used for the approximate electric conductivity calculation of various ionic forms and various concentrations of equihbrium solution. 

FIGURE 5.14. Threshold voltage (sohd Hues) and the critical thickness Dcx (broken line) for the cut-off of the conductance regime of the electrohydrodynamic instabihty against electrical conductivity. Calculation is performed for = 4.7, D = 10 cm s . ... 

Room-Temperature and Elevated-Temperature Electrical Conductivity Calculations for Extrinsic Silicon... 

Electrical conductivity. Calculation of electrical conductivity of a two-component material (solid, fluid) as function of porosity. The following equations are used Voigt model (parallel, upper bound), Reuss model (series, lower bound), arithmetic mean, geometric mean, Krischer and Esdorn model with parameter a, generalized Lichtenecker-Rother model with parameter a. 

Flow and Performance Calculations. Electro dynamic equations are usehil when local gas conditions (, a, B) are known. In order to describe the behavior of the dow as a whole, however, it is necessary to combine these equations with the appropriate dow conservation and state equations. These last are the mass, momentum, and energy conservation equations, an equation of state for the working duid, an expression for the electrical conductivity, and the generalized Ohm s law. 

To calculate electron production must be balanced against electron depletion. Free electrons in the gas can become attached to any of a number of species in a combustion gas which have reasonably large electron affinities and which can readily capture electrons to form negative ions. In a combustion gas, such species include OH (1.83 eV), O (1.46 eV), NO2 (3.68 eV), NO (0.09 eV), and others. Because of its relatively high concentration, its abUity to capture electrons, and thus its abUity to reduce the electrical conductivity of the gas, the most important negative ion is usuaUyOH . 

This computation is also referred to as calculating the zinc equivalent of the alloy. The increase in strength in this alloy series is caused by increased amounts of beta phase in the stmcture. The silicon brasses show similar hardening effects accompanying a second phase. Typical mechanical properties and electrical conductivity for various cast alloys are shown in Table 2. 

Conduction takes place at a solid, liquid, or vapor boundary through the collisions of molecules, without mass transfer taking place. The process of heat conduction is analogous to that of electrical conduction, and similar concepts and calculation methods apply. The thermal conductivity of matter is a physical property and is its ability to conduct heat. Thermal conduction is a function of both the temperature and the properties of the material. The system is often considered as being homogeneous, and the thermal conductivity is considered constant. Thermal conductivity, A, W m, is defined using Fourier s law. 

The determination of the degree of dissociation of cotarnine ° and the good agreement with the values derived from measurements of electrical conductivity with those from the spectrophotometric methods is indirect evidence that no significant part of the undissociated cotarnine is in the amino-aldehyde form. In the conductance calculation, the undissociated part was neglected. If this included a significant amount of amino-aldehyde (i.e., a secondary base), there would be a noticeable discrepancy in the degree of dissociation obtained by the two methods. 

Following the general trend of looldng for a molecular description of the properties of matter, self-diffusion in liquids has become a key quantity for interpretation and modeling of transport in liquids [5]. Self-diffusion coefficients can be combined with other data, such as viscosities, electrical conductivities, densities, etc., in order to evaluate and improve solvodynamic models such as the Stokes-Einstein type [6-9]. From temperature-dependent measurements, activation energies can be calculated by the Arrhenius or the Vogel-Tamman-Fulcher equation (VTF), in order to evaluate models that treat the diffusion process similarly to diffusion in the solid state with jump or hole models [1, 2, 7]. 

Here, we will shortly summarize these results again. After this, we will focus on our recent results for the electrical conductivity. This quantity we calculated using the Kubo-Greenwood formula [8]. 

To interpret the strong dependence of the conductivity from composition, we also evaluated the electronic density-of-states and analyzed its specific atomic contributions. For this discussion and for comparison we also calculated the electrical conductivities and the electronic densitity-of-states using a simplified density-functional (DFT)- based LCAO scheme [12]. 

Furthermore, the electrical conductivities of liquid Na-Sn alloys for the five compositions are determined with the Kubo-Greenwood scheme, using the trajectories from our ab initio MD simulations. The calculated values reproduce the measured strong variation of the conductivity with the Na (or Sn) concentration very well. The small (semimetallic) conductivity of the alloys with nearly equimolar composition can be explained by the position of the Fermi energy between the occupied sp-band of tin and the sp-band of sodium. 

Most minerals in water exist as ions - electrically charged particles that give them an electrical conductivity. The different systems of units that measure their concentration can cause much confusion. For any calculation involving adding different ions to one another it is vital to use one of two systems of equivalents. 

This equation is identical to the Maxwell [236,237] solution originally derived for electrical conductivity in a dilute suspension of spheres. Hashin and Shtrikman [149] using variational theory showed that Maxwell s equation is in fact an upper bound for the relative diffusion coefficients in isotropic medium for any concentration of suspended spheres and even for cases where the solid portions of the medium are not spheres. However, they also noted that a reduced upper bound may be obtained if one includes additional statistical descriptions of the medium other than the void fraction. Weissberg [419] demonstrated that this was indeed true when additional geometrical parameters are included in the calculations. Batchelor and O Brien [34] further extended the Maxwell approach. 

Danek and his group have independently proposed a quite similar model, which they call the dissociation modeV - For this model Olteanu and Pavel have presented a versatile numerical method and its computing program. However, they calculated only the electrical conductivity or the molar conductivity of the mixtures, and the deviation of the internal mobilities of the constituting cations from the experimental data is consequently vague. 

The efficient electric conductivity of such specially-inhomogeneous medium can be calculated in various limiting cases differing by tiie ratio between the local electric conductivity and its average value using methods developed in papers [70-72]. Namely, if the local electric conductivity o(r) slightly differs from the average one [Pg.127]

The fair agreement of expressions (2.67) and (2.71) with experimental data as well as agreement of independently obtained experimental data concerning kinetics of the change of a with the data on equilibrium enabled the author of paper [89] to conclude that the proposed mechanism of effect of hydrogen on electric conductivity of semiconductors can be one of active mechanisms. The heat of total reaction (2.63) calculated from the values found was about 4.6 kcal. 

It follows from calculations, that intensity of flux of zinc atoms incident upon the sensor film in these experiments amounted to 10 - 10 atom/cm, on the average. It is seen from Fig. 4.11, that all experimental points depicting in arbitrary units the rates of increase (sensor) or decrease (evaporating film) of electric conductivity can be well approximated by the linear dependence in a (In d - - ) plot. 

Figure 4.23 shows the results of measuring the electric conductivity of the semiconductor sensor obtained by remote control means from board of the rocket MR-12, along with the data obtained in our experiments and the data of model calculations by other authors. Also shown are the experimental results of similar measurements obtained by other... 

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