Direct current perturbation

Linear polarization resistance (intrusive). The linear polarization resistance (LPR) technique is an electrochemical method that uses either three or two sensor electrodes. In this technique, a small potential perturbation (typically of the order of 20 mV) is applied to the sensor electrode of interest, and the resulting direct current is measured. The ratio of the potential to current perturbations, known as the polarization resistance, is inversely proportional to the uniform corrosion rate. The accuracy of the technique can be improved by measuring the solution resistance independently and subtracting it from the apparent polarization resistance value. The technique is well known (its theoretical basis had already been developed in the 1950s), and it is widely used under full immersion aqueous conditions. 

Electrochemical impedance spectroscopy (EIS) is also commonly employed for analysis of enzymatic electrode systems [11], EIS is performed by overlaying a range of alternating current (AC) perturbation signals to an electrode that is under direct current (DC) bias. A Nyquist plot is then generated, and variations of the frequency response can then be used to interpret limiting mechanisms associated with charge transfer. 

If we now solve the same problem by regarding the /th mode on the perturbed fiber as an induced current within the unperturbed fiber, we replace E, by 6,(0), exp(i, z) in Eq. (22-6) and deduce that the x-directed current has magnitude... 

In this paper, the main features of the two-step method are presented and PNC calculations are discussed, both those without accounting for correlation effects (PbF and HgF) and those in which electron correlations are taken into account by a combined method of the second-order perturbation theory (PT2) and configuration interaction (Cl), or PT2/CI [100] (for BaF and YbF), by the relativistic coupled cluster (RCC) method [101, 102] (for TIF, PbO, and HI+), and by the spin-orbit direct-CI method [103, 104, 105] (for PbO). In the ab initio calculations discussed here, the best accuracy of any current method has been attained for the hyperfine constants and P,T-odd parameters regarding the molecules containing heavy atoms. 

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