Electrical Circuit Elements Research Articles

Analytical Electroacoustic Model of aPiezoelectric Composite Circular Plate

This paper presents an analytical two-port, lumped-element model of a piezoelectric composite circular plate. In particular, the individual components of a piezoelectric unimorph transducer are modeled as lumped elements of an equivalent electrical circuit using conjugate power variables. The transverse static deflection field as a function of pressure and voltage loading is determined to synthesize the two-port dynamic model. Classical laminated plate theory is used to derive the equations of equilibrium for clamped circular laminated plates containing one or more piezoelectric layers. A closed-form solution is obtained for a unimorph device in which the diameter of the piezoelectric layer is less than that of the shim. Methods to estimate the model parameters are discussed, and model verification via finite-element analyses and experiments is presented. The results indicate that the resulting lumped-element model provides a reasonable prediction (within 3%) of the measured response to voltage loading and the natural frequency, thus enabling design optimization of unimorph piezoelectric transducers.

Vibration attenuation using a piezoelectric shunt circuit based on finite element methodanalysis

A numerical model of a beam structure with a piezoelectric actuator bondedto the surface of the structure and an accelerometer placed on the tip can beobtained in the ANSYS Matlab platform. The validated numerical model and theexperimental data allow us to use the obtained finite element model of the completesystem (beam, piezoactuator and accelerometer) as a basis for the design andoptimization of the electrical shunted circuit elements. The obtained optimalelectrical elements of the circuit network have been used in an experimental test toconfirm the numerical result. The analysis has been extended to more complexstructures, such as the dominant mode of vibration of a chassis subframe of acar.

Power balancing for a new class of non-linear systems and stabilization of RLC circuits

In this paper the method of power shaping, as recently introduced for the stabilization of non-linear RLC circuits, is generalized to a larger class of systems showing similarities (and important differences) with the class of port-controlled Hamiltonian systems. Other than for port-controlled Hamiltonian systems, the stabilization of these new systems is not stymied by a ‘dissipation obstacle’ and, in fact, every power-shaping controller is power balancing as well. It is shown that the power-shaping controller can be realized as a port-controlled Hamiltonian system connected by means of a gyrator to the plant. The theoretical results are applied to the class of non-linear RLC circuits described by Brayton–Moser's equations, and a physical implementation of the controllers in terms of standard electrical circuit elements is given.

Neural Network Models for Finline Discontinuities

The radial basis network is used as the finline discontinuities electromagnetic artifical neural network(EM‐ANN) models. EM software analysis is employed to characterize finline discontinuities. EM‐ANN models are then trained using physical parameters and frequency as inputs and equivalent electric circuit element parameters of finline discontinuities as outputs. Once trained , the EM‐ANN models can simulate equivalent electric circuit element parameters of finline step, notch and strip very fast and efficiently.

Potentiodynamic electrochemical impedance spectroscopy: lead underpotential deposition on tellurium

Lead underpotential deposition (upd) on tellurium and the effect of halides (iodide, bromide and chloride) in the upd and the monolayer anodic oxidation have been investigated with potentiodynamic electrochemical impedance spectroscopy (PDEIS). PDEIS gives, with a virtual spectrometer, the ac and dc responses of the electrochemical interface along the trajectory of a potential scan. The built-in analyser decomposes the total response into the constituents related to the elements of the equivalent electric circuit and gives the dependences on the potential of the double layer capacitance C dl and the parameters of the Faraday impedance. No adsorption capacitance was found in the equivalent circuit of Pb upd on tellurium. Pb upd manifests itself in the increase of the double layer capacitance in the negative scan, additional C dl increase in the positive scan below the oxidation potential of Pb adatoms and the decrease in C dl observed during monolayer anodic stripping from the tellurium surface. The most significant halide effect has been found for iodide. Iodide stabilises the monolayer against the anodic oxidation.

Lumped Element Modeling of Piezoelectric-Driven Synthetic Jet Actuators

Abstract : This paper presents a lumped element model of a piezoelectric-driven synthetic jet actuator. A synthetic jet, also known as a zero net mass-flux device, uses a vibrating diaphragm to generate an oscillatory flow through a small orifice or slot. In lumped element modeling (LEM), the individual components of a synthetic jet are modeled as elements of an equivalent electrical circuit using conjugate power variables. The frequency response function of the circuit is derived to obtain an expression for Q(sub out)/V(sub AC), the volume flow rate per applied voltage. The circuit is analyzed to provide physical insight into the dependence of the device behavior on geometry and material properties. Methods to estimate the model parameters are discussed, and experimental verification is presented. In addition, the model is used to estimate the performance of two prototypical synthetic jets, and the results are compared with experiment.

An electrochemical impedance spectroscopy study of the corrosion behaviour of PVD coated steels in 0.5 N NaCl aqueous solution: Part I. Establishment of equivalent circuits for EIS data modelling

Electrochemical impedance spectroscopy (EIS) is a powerful analysis technique, which can provide a wealth of information on the corrosion reactions, the mass transport and the electrical charge transfer characteristics of physical vapour deposition (PVD) ceramic coated steels in an aqueous solution. Although a huge amount of potentially useful data can be generated using the EIS technique, these data need to be carefully interpreted. This is usually done using an ‘equivalent circuit’ which comprises an assembly of electrical circuit elements that model the physicoelectric characteristics of the electrode/solution interface. A systematic study of PVD ceramic (TiN and CrN) coated mild steel and AISI 316L stainless steel was carried out using the EIS technique as the coated systems were immersed in 0.5 N NaCl solution. The relevant equivalent circuits (ECs) are developed by non-linear least square curve fitting to the exponential data to build up a description of the influence of different coatings deposited on steels on the temporal evolution of corrosion in such systems. Constant phase elements describing the non-ideal (e.g. capacitive) characteristics of the electrochemical interface, designated as Q, are introduced to achieve a more accurate simulation of electrochemical corrosion. The mass transport behaviour is also dealt with, through the introduction of diffusion-related elements such as Warburg (designated as W) and cotangent–hyperbolic (designated as O) impedance. The use of these elements significantly improves the quality of fit of the simulation to the EIS data. Finally, the physical validity of the proposed models is discussed in terms of the current–frequency response of the coated steel electrode, during extended corrosion degradation over a period of immersion of up to one week.

Simulation of electrooptical effects and dynamics of ferroelectric liquid crystals

The behavior of ferroelectric liquid crystals in an external electric field is simulated numerically. The equations that describe the dynamics of the director of a liquid crystal are derived within the continuum theory of elasticity with due regard for compressibility of smectic layers, finite anchoring energy, and dielectric properties of orienting coatings and external elements of a real electric circuit. These equations make the basis for simulation of the electrooptics of ferroelectric liquid crystals. The specific features and mechanisms of the surface-stabilized bistability and hysteresis-free electrooptical switching (the V-shape effect) are discussed.

Electrochemical Impedance of Anodic Oxide Films on Zr-2.5 Nb

Electrochemical impedance spectra are presented for anodic oxide films grown on Zr-2.5Nb. The spectra are interpreted in terms of a model of parallel generalized Debye responses. The model parameters are linear analogue electric circuit elements (resistors and generalized constant-phase-element capacitors) that can be associated with macro (oxide thickness) and microscopic properties (surface fractal dimension, cracks, and fissures) of the oxide. © 2002 The Electrochemical Society. All rights reserved.

Studies of copper corrosion inhibition using electrochemical quartz crystal nanobalance and quartz crystal immittance techniques

Several copper corrosion inhibitors were tested including benzotriazole (BTA), thiourea, potassium ethyl xanthate (KEtX), octadecyl mercaptan, and Bricorr-288®. The corrosion breakdown potentials were evaluated using the electrochemical quartz crystal nanobalance (EQCN) technique, by recording linear potential scan voltammetric ( i– E) and piezogravimetric ( m– E) characteristics. Effects of single inhibitors and their mixtures on the value of the breakdown potential were investigated. Previously found synergistic effects for a mixture of BTA+KEtX and a mixture of TU+KEtX inhibitors were confirmed. The most effective among the copper corrosion inhibitors tested appeared to be Bricorr-288. The representative inhibitor films were subsequently tested using the quartz crystal immittance (QCI) technique. New equations based on experimental admittance data were derived to characterize the film acoustic resistance and the resonator parallel capacitance. On the basis of these equations, a new procedure to evaluate passive elements of the equivalent BVD electrical circuit, has been proposed. A decrease in the admittance maximum, appearing near the resonance frequency, was observed for octadecyl mercaptan and Bricorr-288 films on copper.

Error field amplification and rotation damping in tokamak plasmas.

Toroidal rotation is normally very weakly damped in plasmas that are magnetically confined in the nominally toroidally symmetric tokamak. However, a strong damping of toroidal rotation is observed as such plasmas approach marginal stability for perturbations that produce a kinklike distortion of the plasma. It is shown that the damping of toroidal rotation by very small departures of the magnetic field from toroidal symmetry is greatly enhanced as marginal stability is approached. The response of a plasma to perturbations is studied using a set of electrical circuit elements, which provide an equation for the rotational damping that requires minimal information about the plasma.

Modelling of the Thin Organic Film/Carbon Steel Interface

ABSTRACTThe electrochemical impedance spectroscopy (EIS) has been used for the modelling of the alkyd organic film/carbon steel interface in 3% NaCl solution. Both the dielectric properties of the organic film and the corrosion processes of the metallic substrate were investigated with this method. Analysis of the impedance spectra (Nyquist and Bode plots) and the interpretation with the fitting software developed by Boukamp, established the presence of two time constants in the first 250 immersion hours. One time constant concerning the organic layer describes the electrical and barrier properties of film. The second time constant concerning the substrate represents the corrosion reactions at the film/metal interface. For long immersion periods, after the formation of the conductive pathways in the film and the development of the diffusion processes, are necessary another two time constants concerning these phenomenons. The error magnitude between the measured and calculated data with these electric equivalent circuits is satisfactory. The physical properties obtained from the principal elements of the equivalent electric circuits are in concordance with those obtained from others testing methods.

Cement-based electronics

Cement-based electronics in the form of electrical circuit elements (conductor and diode in the form of a pn-junction), sensors of strain and damage, thermistor and thermoelectric device are reviewed. They enable a concrete structure to provide electronic functions.

Dielectric properties of ZnSexCdS1-x alloy films

Al-ZnSexCdS1-x-Al structures are formed by thermal vacuum evaporation at 470 K in the entire range of composition. The frequency and temperature response of these structures in the frequency and temperature ranges 1-100 KHz and 300-450 K respectively are studied. In the present study Cole-Cole (permittivity) and Grant's (conductivity) representations are used assuming that the present films obey Debye's dispersion relation. From the representative Argand diagrams the equivalent electrical circuit elements are obtained for all the samples studied. The relaxation times are in the range 10-22 μs. The spread parameter (α), a measure of width of energy barrier lies in the range 0.21-0.66.

Mechanics of blood supply to the heart: wave reflection effects in a right coronary artery.

Mechanics of blood flow in the coronary circulation have in the past been based largely on models in which the detailed architecture of the coronary network is not included because of lack of data: properties of individual vessels do not appear individually in the model but are represented collectively by the elements of a single electric circuit. Recent data from the human heart make it possible, for the first time, to examine the dynamics of flow in the coronary network based on detailed, measured vascular architecture. In particular, admittance values along the full course of the right coronary artery are computed based on actual lengths and diameters of the many thousands of branches which make up the distribution system of this vessel. The results indicate that effects of wave reflections on this flow are far more significant than those generally suspected to occur in coronary blood flow and that they are actually the reverse of the well known wave reflection effects in the aorta.

Artificial molecule realization of a magnetic wall

The design of magnetic materials can be achieved with artificial magnetic molecules formed by electrically small loop antennas loaded with passive electrical circuit elements. A time derivative Lorentz material response is achieved with a series resistor and capacitor load. It is shown that the parameters of this magnetic molecule can be selected to yield a time derivative Lorentz material that acts as a highly conducting magnetic wall.

Passive artificial molecule realizations of dielectric materials

The design of dielectric materials with artificial molecules formed by electrically small dipole antennas loaded with passive electrical circuit elements is considered. Variations in the antenna loads lead to known and generalizations of known dielectric material models. These artificial dielectrics are characterized in terms of their equivalent susceptibilities and polarization vectors both in the frequency and time domains. With suitable choices in the antenna loads one can design the loss and dispersion properties of the resultant materials.

Lineår modelling of oscillating water columns including viscous loss

Wave-energy converters of the oscillating-water-column (OWC) type with pneumatic power take-off may be modelled by the so-called ‘applied-pressure’ (or ‘pressuredistribution’) description. For wavelengths which are not too short, the alternative ‘rigid-pistoa’ description is also applicable. The paper presents a transformation between the two descriptions. A mechanical mass-spring equivalent model of the OWC is also presented together with analog electric circuit diagrams. Some account of viscous energy loss is taken into consideration by introducing a mechanical loss resistance into the rigid-body description, and corresponding analog electric circuit elements for both descriptions are included. Some methods are presented to determine experimentally the mechanical loss resistance for a two-dimensional OWC.

Reviews Of Acoustical Patents

Abstract

Precision Tests of a Quantum Hall Effect Device DC Equivalent Circuit Using Double-Series and Triple-Series Connections.

Precision tests verify the dc equivalent circuit used by Ricketts and Kemeny to describe a quantum Hall effect device in terms of electrical circuit elements. The tests employ the use of cryogenic current comparators and the double-series and triple-series connection techniques of Delahaye. Verification of the dc equivalent circuit in double-series and triple-series connections is a necessary step in developing the ac quantum Hall effect as an intrinsic standard of resistance.