impedance

Запропоновано структуру математичного моделювання корозії на межі «метал- електроліт». Визначено ємність і ефективну товщину подвійного електричного шару без урахування розподілу зарядів у електроліті.

The structure of mathematical modelling of corrosive processes on a interface ‘metal- electrolyte’ is offered. Capacity and effective thickness of double electric layer without the account of distributing of charges in an electrolyte is determine.

The problem of the elastic SH-wave diffraction from the semi-infinite interface defect in the rigid junction of the elastic layer and the half-space is solved. The defect is modeled by the impedance surface. The solution is obtained by the Wiener- Hopf method. The dependences of the scattered field on the structure parameters are presented in analytical form. Verifica¬tion of the obtained solution is presented.

The dependence of the active and reactive impedance components of a three-element electrical circuit of substitution of a biological object on the change of the parameters of the electrode impedance is investigated.

The freshness of the meat is one of the indexes of its quality. However, it is often frozen to be transported and stored. After unfreezing, it is offered to a consumer as a fresh one. Quality of that meat is worse, but the price is, mainly, identical to the cost of meat that wasn’t frozen. 

Influence of near-electrode impedance of capacitive sensor on result of measuring the active and reactive components of the admittance of electrolytic objects is considered. Near-electrode impedance is formed by capacity of the double layer and the Warburg impedance. Reactive and active components of admittance are the informative parameters of object’s electro physical parameters, in particular dielectric permittivity and specific conductivity.

Impedance spectroscopy is widely used to study biological, physical and chemical objects, for example in biomedical measurements, in study of the materials properties, particularly on micro- and nanoscale, for corrosion monitoring and diagnostics, for control of batteries, fuel cells. Often research is carried out on a objects under non-laboratory conditions. A good example of such research is the use of impedance spectroscopy for testing of corrosion-resistant coatings on various steel structures such as bridges, pipelines and other.

Development of specialized portable measurement tools for impedance spectroscopy is quite challenging and up-to-date technical task. Portable impedance analyzers are required to satisfy certain criteria among which the most important are the following: stability of metrological characteristics of measurement channel over a wide frequency range, high dynamics, fast frequency sweep and the probe signal with appropriate step as well as high resolution of impedance/admittance measurement results. Autobalancing circuits are widely used in impedance analyzers design.

The applications of magnetoresistive structures based on semiconductor crystals of InSe for high precision measurement of the magnetic field are outlined in this article. Possibilities of using magnetic field sensors based on InSe structures for revealing the armour military vehicles are discussed. The impact of metal impurities on the layered structure of the semiconductor material as referred to the strong covalent bond within the layers as well as the weak van-der-Waals bond in the interlayer space is studied.

It was established that natural and Ca modified zeolite inhibit steel corrosion in the medium of low acid rain. The Ca-containing zeolite inhibit the steel corrosion in the most effective way. The protective effectiveness of the alkyd coatings filled with zeolites can be placed in the following order:  unmodified < with natural zeolite < with Ca-containing zeolite.  Встановлено, що природний та модифікований кальцієм цеоліти інгібують корозію сталі в середовищі слабкокислих дощових опадів. Найефективніше інгібує корозію сталі Ca-вмісний цеоліт.

The model of impedance subdiffusion based on the Cattaneo equation in fractional derivatives in applications to multilayer nanostructures is considered. Nyquist diagrams with changes of the parameter $\tau$ (time for which the flow is delayed with respect to the concentration gradient) and the subdiffusion coefficient $D_{\alpha }$ are calculated.