Abstract: AC impedance experiments have been performed on three-electrode plastic LiCoO 2 /graphite batteries using a thin reference electrode. Various shapes, positions, and types of reference electrodes have been tested to select the most reliable and accurate configuration, Once biphasic lithium insertion materials, such as Li 4 Ti 5 O 12 , were identified as the optimum material for the reference electrode, the evolution of the Nyquist plots for each electrode of the battery was followed as a function of the cycle number or storage time. An analysis of the impedance diagrams for each electrode allowed us to determine the interface responsible for the capacity loss during cycling or storage in plastic Li-ion cells.

Abstract: The corrosion of a mild steel was examined in two aerated neutral aqueous solutions, defined as reference solution (0.2 g L−1NaCl) and as Σ-solution (1.3 g L−1NaCl + 0.63 g L−1NaHCO3 + 0.27 g L−1Na2SO4). Their composition was chosen on the basis of the physical and chemical properties of certain natural waters. The solutions simulated the least (reference solution) and the most (Σ-solution) aggressive waters of the Sebou river in Morocco, as determined after a four-year examination (1991–94), at 13 pump stations located along the river. Various experimental methods were used to determine the corrosion mechanism. Cathodic range voltammetry using a rotating disc allowed the kinetics of oxygen reduction process to be determined. Since the conductivity of the solutions were low, the potential was corrected for ohmic drop estimated through the high frequency limit in the Nyquist diagrams (electrochemical impedance spectroscopy) as well as the current interrupter method. After correction, the polarization curves revealed a diffusion plateau attributed to dissolved oxygen reduction. At the plateau, a two-step mechanism was derived involving oxygen diffusion through the hydrodynamic layer and through a porous inner layer formed by the corrosion products. This inner layer could not be observed by SEM, but both EIS and EHD (electrohydrodynamic impedance) confirmed the presence of a thin porous dielectric layer. At the open circuit potential, the corrosion rate was determined by the diffusion rate of dissolved oxygen in the Σ-solution, and by charge transfer in the reference solution. This shows that the corrosion mechanism strongly depends on the electrolyte and its conductivity.

Abstract: A method relying on the time response includes acquiring the time response waveforms of all the acceleration sensors obtained when a table for vibration isolating is excited by a pseudo impulse (step S 802 ), making the frequency analysis for the time response waveforms (step S 803 ), calculating a mode matrix φ (step S 804 ), and implementing the mode matrix φ in a non-interacting control system for each vibration mode (step S 805 ). A method relying on the frequency response includes acquiring the frequency responses to all the acceleration sensors, displaying the acquired frequency responses in a Nyquist diagram, obtaining a parameter (φ) fitted to each Nyquist circle, and implementing the obtained parameter φ in a non-interacting control system for each vibration mode.

Abstract: This chapter considers linearly parametrized plants whose parameters are normally distributed and addresses the problem of analyzing the image in the Nyquist plane of a set of these plants defined by a confidence ellipsoid in the parameter space. The image in the Nyquist plane of such set of plants is made up of ellipses at each frequency. However, the connection between different frequencies makes the mapping nontrivial. We show that the probability level linked to this image in the Nyquist plane is larger than that of the confidence region in the parameter space. This is due to the fact that the mapping between the parametric and frequency domain spaces is not bijective.

Abstract: Tio2 treated in hydrogen atmosphere showed enhanced photocatalytic activity in degrading the sulfosalicylic acid (ssal),the results of the electrochemical impedance spectroscopy (eis) investigation showed that the diameters of the capacitive arcs for the h-tio2 were much smaller than those of bare tio2 and thermally treated tio2 in air, indicating that the charge transfer of the h-tio2 occurs more rapidly, thus inviting a higher photocatalytic activity. when an external bias was applied on the h-tio2, the arc of the eis nyquist plot decreased obviously than without the bias, suggesting more efficient separation of the photo-generated carriers.

Abstract: This paper introduces new and fast ways of systematically calculating the limiting values of the parameters of PID-action controllers for systems that are open-loop stable, or unstable, minimum phase, or non-minimum phase, and can contain explicit time-delay terms. The technique presented, which is based on the axis-crossing form of Nyquist's stability theorem, can be readily used for the design of PID controllers to meet certain closed-loop stability and performance requirements. A summary of the background development is given and it is then shown how, by using a simple feature available in most symbolic algebra environments, a much faster version of the proposed method, which avoids the need to calculate any Nyquist diagrams, can be obtained for systems with no explicit time-delay term. A recent complete analytical solution to the PID compensator that results in a very significant reduction in the computing time, yielding almost real-time results, is also introduced. The methods proposed can be extended to develop robust controllers for systems with uncertainties, and present a visual characterization of all PID controllers meeting the desired performance criteria for such systems. Other time-domain performance requirements such as the Integral of Time and Absolute Error criterion can also be employed to select an optimal operating point from the allowable set of controller parameters. An application of these tools to the fan-speed control of the Pegasus aircraft gas-turbine engine, used in the Harrier jump-jet, will be presented.

Abstract: Different plot formats of electrochemical impedance spectroscopy including Nyquist, Admittance, Bode, capacitance plane plot and Warburg plot are induced The characteristics of different plot formats for ideal polarized electrode, kinetic controlled electrode, both kinetic and mass transfer controlled electrode and their applications are also analyzed

Abstract: The dependence of the impedance of the electrode double layer of mercury electrode on frequency around the potentials of the tensammetric peaks of single-stranded and double-helical polynucleotides and DNA was studied From the frequency dependence of the impedance of the electrode double layer represented in a complex impedance plot (the imaginary component Z'' is plotted against the real component Z', Cole-Cole or Nyquist plot) the electric equivalent circuit of the electrode covered with adsorbed DNA layer was determined It was concluded the desorption of denatured ssDNA is accompanied by higher dielectric losses than the desorption of native dsDNA This can be explained by the higher flexibility of ssDNA compared to the dsDNA The capacitance peak of single stranded poly A observed at pH 8 around -13 V splits at low frequencies in two peaks

Abstract: We examine fluctuations in cluster evaporation and growth and express these, using the Nyquist and Kubo relations [1,2], in terms of the resistance to single-cluster motion along the coordinate of cluster size. If successful in future development, the methods introduced here will have application to the abstraction of nucleation rates from computer simulations of individual-cluster evaporation/growth events.