Conductivity variation

Many subcontractors supply product or services to several vehicle manufacturers. Therefore by harmonizing the standards by which subcontractor development will be conducted, variations in the approach to subcontractors will be minimal. 

On the basis of the experimental data given here one can maintain that kinetics of chemosorbtion and kinetics of conductivity variation caused by the chemosorbtion are described by the same function. 

Fig. 3.7. Relationship between the stationary values of conductivity aha and the values of initial conductivity variation rates (.da/dOt-o = v for various temperatures of hot filament (i. e., various concentrations of H-atoms in the vessel volume). 1 - 300 C 2 - 380°C.

Above reasoning can be confirmed by a number of experimental results which showed that although with some peculiarities irrelevant to the properties of semiconductor sensors the correlation between the amount of the atoms in the flux incident on the target, or their surface concentration, and the variation (increase, if we are dealing with semiconductor of n-type) of the target conductivity takes place [28]. Based on the relations cited in Chapter 1, one can estimate concentrations (i. e., flow intensities) of these particles in vacuum or in gaseous medium if these values are quite small, using the values of conductivity variation of the semiconductor film. 

Applicability of the above equation for description of the effect of radical adsorption on conductivity of ZnO film is displayed by the example of CHs-radical (see Fig. 3.19). The figure shows a fairly linear dependence of the experimental curve 1 plotted in the cobrdinates a/a - t over a wide range of time and conductivity variation [41]. 

Since all glasses have comparable values for (Tq, isothermal conductivity variations represented in Fig. 4.2 are related to AHf/2 and AH variations... 

So from electrical data, it is possible to get information on partial thermodynamic functions of the salt and then develop thermodynamic models for quantitative interpretation of the conductivity variation with composition. These models are not very different from those already developed for molten salt mixtures or metallic alloys. 

Although two peaks of comparable amplitude are presented (see Fig. 2.1), only the first, denoted as Mi, is actually related to the carriers release from trap, the second, denoted as M2, is connected with dark conductivity variation with temperature (DC conductivity-determined relaxation peak related to the movement of equilibrium carriers). 

Substantial insight has been achieved Into the suitability of BLM matrices as the basis for development of a transducer where control of analytical signals is determined by transmembrane ionic conduction variations. The embedding of molecular receptors or complexing agents into BLM has led to the development of selective transducers for organic species, 13-61 whereby such organics would complex with the receptor to alter membrane character and therefore ion current across the membrane. 

The conductivity variation curve shows a maximum, the position of which depends on the type of dopant. This maximum is located at 15 and 9mol% of dopant for Zr02-CaO and Zr02-Y203 systems, respectively (see Fig. 6) [13]. 

Thin films, to attain enough sensitivity and response time, of oxide materials normally deposited on a substrate are typically used as gas sensors, owing to their surface conductivity variation following surface chemisorption [183,184], Surface adsorption on a Sn02 film deposited on alumina produces a sensitive and selective H2S gas sensor [185]. In addition, a number of perovskite-type compounds are being used as gas sensor materials because of their thermal and chemical stabilities. BaTi03, for example, is used as sensor for C02 [183],... 

There is a striking similarity between the experimentally observed and the theoretically calculated profiles, and all four characteristic features occur in both. The calculated location of the minimum, which mainly depends on the vacancy mobility, is close to the location observed in the experiment. The computed temperature dependence of the depth of the minimum corresponds with the results of the measurement. Obviously, the stoichiometry polarization model of resistance degradation correctly predicts the conductivity variations. In particular the almost quantitative agreement of the very characteristic shape of the conductivity distribution proves the validity of the existing model described above. It should be noted that in the calculations only the hole mobility is chosen such that the theoretically and the experimentally observed depth of the minimum is similar, but all other parameters used in the simulation are taken from literature [77, 336, 338],... 

Fig. 5.9. Electrical conductivity variation versus weight fraction of SWNTs in the blend (filled circles). The percolation threshold is found to be 11%. The solid line is the fit of the percolation model [132].

Answer 4.12 The changes over the measured period were small (only 1.5 °C, from 120 to 1671/min, and from 523 to 578ps/cm. The question whether these temperature, discharge, and conductivity variations are significant is answered by comparison of the changes to the accuracy of the measurements. In the discussed case measurements were done to + 0.2 °C, + 5 1/min, and + 15 ps/cm. Thus the observed changes were of significance. 

Figure 29. a) Conductivity variation in the system /J-Agl-AgCl (volume fraction) for different temperatures."8 b) Conductivity variation in CaFi-BaF heterolayers as a function of temperature for different periods (spacings)."9 (Reprinted from N. Sata, K. Eberman, K. Eberl and J. Maier, Mesoscopic fast ion conduction in nanometre-scale planar heterostructures. Nature. 408, 946-949. Copyright 2000 with permission from Macmillan Magazines Ltd.)... 

Note that the differential sensitivities are vector functions, because they characterize the sensitivity of the vector electric and magnetic fields to the conductivity variation. From the last formulae we see that Green s electromagnetic tensors provide the sensitivity estimation of the electromagnetic field to the model conductivity. 

The argument in the expressions for the Prechet differentials, FE,H b,Aa), consists of two parts. The first part, at, is the background conductivity distribution, for which we calculate the forward modeling operator variation the second part, Aa, is the anomalous conductivity, which plays the role of the background conductivity variation. We will use below the following simplified notations for the Fr6chet differentials... 

The term (o — o,c) represents the potential drop through the electrolyte. As defined here, the numerical evaluation of the potential drop requires accounting for the variation in electrolyte conductivity within the diffusion layer. An alternative approach is to define the Ohmic potential drop as being that calculated using Laplace s equation with a uniform solution conductivity. In this case, an additional term is required to accotmt for the influence of the conductivity variation within the diffusion layer on the measured potential. This is incorporated into a concentration overpotential, discussed in Section 5.7.3. 

Makurat, A., Barton, N. and Rad, N.S. 1990. Fracture conductivity variation due to normal and shear deformation. In Proe. Int. Symp. on Rock Fractures, Loen, Norway, pp. 535-540. 

Kuhlmann U, Goldau R, Samadi N, Graf T, Gross M, Orlandmi G, et al. Accuracy and safety of online clearance monitoring based on conductivity variation. Nephrol Dial Transplant 2001 16 1053-8. 

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