Electrical Circuit Elements Research Articles

A generalized model of the equivalent circuits in the electrochemical impedance spectroscopy

The electrochemical impedance spectroscopy (EIS) is widely used in electrochemical research in spite of some ambiguous issues concerning the data evaluation and interpretation. The quantitative evaluation of EIS data takes place via the application of equivalent electrical circuits (EECs), which describe the transfer function of the electrochemical process in terms of electrical circuit elements: resistance, capacitance and other, more specific elements, e.g. the Warburg impedance and the Constant Phase Element (CPE). There is a general agreement among electrochemists that the CPE is inherently related to the dispersion of the parameters (time constants) of the EEC. The measured impedance data contains the effects of the EEC, determined by the kinetics of the electrochemical reaction and by the structure of the electrode surface and, superimposed to it, the effect of the parameter dispersion (“distributed elements”), which spreads the characteristic shapes of the ideal EEC elements. One of the main difficulties in evaluation of EIS data is to differentiate between the effects of the EECs and the distributed elements (CPE). Instead of separation, this paper proposes a model incorporating both the EEC and the CPE in the same mathematical formulation, also proposing a method to identify the time constants of complex EECs combined with the dispersion of time constants. The final equations are linear, in contrast to the general trends in impedance data analysis, therefore the advantages of the linear transformations of originally nonlinear problems is also discussed. The theory is checked on the quinhydrone redox system and also on simulated impedance data.

Little Red Riding Hood: An Analogy to Teach Simple Electric Circuits

In this study, an analogy has been developed to teach students electric circuits in a more concrete way. A connection between the elements of electric circuits and the characters in the Little Red Riding Hood story has been established to teach how simple electric circuits work. In addition to the similarities in the story, we have indicated where the analogy between the analogue concept (Little Red Riding Hood) and the target concept (simple electric circuits) breaks down, and suggested several ways to address any misconceptions that might arise during the implementation.

Understanding the Improved Vapor Sensor Device Performance of Dual Surface Engineered WO3 Nanospheres Using Semi-Quantitative Energy Band Model

Fast responding room temperature ethanol sensor device, having high detection range, was developed employing dual surface engineered (using palladium (Pd) and Reduced Graphene oxide (RGO)) WO3 nanospheres as the sensing layer. Three different types of vapor sensor devices, viz. i) Pd/WO3 (Sensor 1), ii) RGO/WO3 (Sensor 2) and iii) Pd/RGO/WO3 (Sensor 3) were fabricated to study the influence of each of the elements and to account for its exact contribution in improving the gas sensor device performance towards alcohol vapors. Dual surface engineered device (Sensor 3) was found to offer remarkably superior sensing performance in terms of response magnitude, response time and recovery time with a very high detection range (1-700 ppm) at room temperature (~ 27 °C), compared to any of its single surface modified device counterpart (Sensor 1 or Sensor 2). A comprehensive discussion elucidating the individual role of RGO and Pd on WO3 has also been presented employing a semi-quantitative energy band model in correlation with the corresponding electrical equivalent circuit elements.

Мобильное приложение для демонстрации основных понятий радиоэлектроники

In the process of studying the basics of the theory of signal transmission and acquaintance with the elements of electrical circuits it is important to demonstrate the mechanism of their work. For this, as a rule, a special laboratory workshop is required, inaccessible during lectures. The developed mobile application “SAoS” works in an interactive mode and does not require special programming skills. It allows the simulation of signals and operations on them using generators, adders, multipliers and various filters included in the structural diagram. The received signal is displayed in the form of an oscillogram and an amplitude spectrum.

Microtubules as Sub-Cellular Memristors

Memristors represent the fourth electrical circuit element complementing resistors, capacitors and inductors. Hallmarks of memristive behavior include pinched and frequency-dependent I–V hysteresis loops and most importantly a functional dependence of the magnetic flux passing through an ideal memristor on its electrical charge. Microtubules (MTs), cylindrical protein polymers composed of tubulin dimers are key components of the cytoskeleton. They have been shown to increase solution’s ionic conductance and re-orient in the presence of electric fields. It has been hypothesized that MTs also possess intrinsic capacitive and inductive properties, leading to transistor-like behavior. Here, we show a theoretical basis and experimental support for the assertion that MTs under specific circumstances behave consistently with the definition of a memristor. Their biophysical properties lead to pinched hysteretic current–voltage dependence as well a classic dependence of magnetic flux on electric charge. Based on the information about the structure of MTs we provide an estimate of their memristance. We discuss its significance for biology, especially neuroscience, and potential for nanotechnology applications.

Realization of Weyl semimetal phases in topoelectrical circuits

In this work, we demonstrate a simple and effective method to design and realize various Weyl semimetal (WSM) states in a three-dimensional periodic circuit lattice composed of passive electric circuit elements such as inductors and capacitors (LC). The experimental accessibility of such LC circuits offers a ready platform for the realization of not only various WSM phases but also for exploring transport properties in topological systems. The characteristics of such LC circuits are described by the circuit admittance matrices, which are mathematically related to the Hamiltonian of the quantum tight-binding model. The system can be switched between the Type-I and Type-II WSM phases simply by an appropriate choice of inductive or capacitive coupling between certain nodes. A peculiar phase with a flat admittance band emerges at the transition between the Type-I and Type-II Weyl phases. Impedance resonances occur in the LC circuits at certain frequencies associated with vanishing eigenvalues of the admittance matrix. The impedance readout can be used to classify the Type-I and Type-II WSM states. A Type-I WSM shows impedance peaks only at the Weyl points (WPs) whereas a Type-II WSM exhibits multiple secondary peaks near the WPs. This impedance behaviour reflects the vanishing and non-vanishing density of states at the Weyl nodes in the Type-I and Type-II WSM phases, respectively.

Memristive properties of solar cells based on perovskite and polymer composite

Organic-inorganic halide perovskites recently have emerged as a perspective material for using in solar cells. This material has many perspective properties, one of them is the ion migration. Modern ionic memristors, electric circuit elements that can change its resistance depending on the current flowing through it, is based on this phenomenon. In this paper, we present the experimentally obtained memristic properties in the perovskite solar cell, which contains composite of perovskite and polymer as absorbing layer instead of pure perovskite.

Fuzzy-multiple estimates of the parameter uncertainty influence in the computing devices elements calculating theory

A method for obtaining estimates for the scatter errors of endogenous characteristics in models for calculating the parameters of communication lines for elements of modern high-speed computing devices in the form of multilayer printed circuit boards is presented. The described methodology for taking into account the uncertainty of exogenous parameters of models in ratios for determining the cross-sectional area and spacing of conductors, delay parameters in short and long communication lines, allows to obtain a forecast of providing of signal integrity, providing of optimized matching of electric circuit elements, and observing of technological requirements for physical, mechanical and geometrical parameters of multilayer printed circuit boards. This technique is based on the theory of fuzzy sets and consists in using a modified form of the heuristic principle of generalization in the transition to fuzzy-sets arguments in the analytical calculation relationships for a number of the most important characteristics of communication lines. A number of examples of the application of the described technique is presented.

The application of mathematical simulation for solution of linear algebraic and ordinary differential equations in electrical engineering

The application of mathematical simulation for the solution of linear algebraic and ordinary differential equations regarding to complex electrical circuits, systems of automatic control and regulation is discussed in the paper. MatLab software package of mathematical simulation and one of its built-in environments - Simulink were chosen to be used in the experiment. MatLab is the most commonly used application in engineering practice in comparison with the other similar programs and it has proved to be reliable for technical calculations. The calculation methods of complex electrical circuits by the solution of linear algebraic and differential equation systems were developed and tested. The equations of electric equilibrium were written for each element of an electric circuit on the basis of Ohm’s and Kirchhoff’s laws. The example of the calculation of branches currents and nodal potentials of electric circuit by the matrix method in MatLab was presented. The approximated polynomial function was calculated and its graph was plotted applying the developed technique. Thus, the coincidence with the original data was proved. The calculation of differential equations of successively connected inductive and resistive elements of electric circuit was made in Simulink environment. Finally, the dependences of voltage and current on time were found using the direct Laplace transformation. The graphs were plotted due to the application of the oscilloscope built into the program. It has been concluded that the application of mathematical simulation for engineering calculations in order to solve the problems of automatic control and power engineering is the most suitable and universal technique.

An investigation of the electromechanical coupling and broadband shunt damping in composite plates with integrated piezo-patches

The popularity of laminated composite plate-like structures is increasing in various engineering applications. Piezoelectric patches with electrical circuit elements can be integrated into these structures for shunt damping applications. For analyzing the shunt damping performance of these systems, precise modeling tools are required, which consider the two-way electromechanical coupling between the piezo-patches and the host plate. This study aims to identify the system parameters which affect the electromechanical coupling coefficient, a metric for measuring the effectiveness of mechanical-to-electrical energy conversion. For that purpose, a thorough investigation is performed to determine the critical system parameters and their combined effects on the electromechanical coupling coefficient of laminated composite plates with surface-bonded piezo-patches. First, the first four natural frequencies of the electromechanical system are obtained using the Rayleigh–Ritz method for various patch sizes. Then, the electromechanical coupling coefficient variations for a different set of system parameters are presented. Later, to demonstrate the applicability of the developed methodology for a broader frequency range, four independently shunted piezo-pairs are attached to the plate. The contours of electromechanical coupling coefficient values with respect to ply angle and patch-pair size are presented for the first four modes. Finally, the vibration amplitudes are successfully reduced for these modes using the optimal system parameters.

Quantized Single-Ion-Channel Hodgkin-Huxley Model for Quantum Neurons

The Hodgkin-Huxley model describes the behavior of the cell membrane in neurons, treating each part of it as an electric circuit element, namely capacitors, memristors, and voltage sources. We focus on the activation channel of potassium ions, due to its simplicity, while keeping most of the features displayed by the original model. This reduced version is essentially a classical memristor, a resistor whose resistance depends on the history of electric signals that have crossed it, coupled to a voltage source and a capacitor. Here, we will consider a quantized Hodgkin-Huxley model based on a quantum memristor formalism. We compare the behavior of the membrane voltage and the potassium channel conductance, when the circuit is subjected to AC sources, in both classical and quantum realms. Numerical simulations show an expected adaptation of the considered channel conductance depending on the signal history in all regimes. Remarkably, the computation of higher moments of the voltage manifest purely quantum features related to the circuit zero-point energy. Finally, we study the implementation of the Hodgkin-Huxley quantum memristor as an asymmetric rf SQUID in superconducting circuits. This study may allow the construction of quantum neuron networks inspired in the brain function, as well as the design of neuromorphic quantum architectures for quantum machine learning.

Performance evaluation of a low flow rate Annular Linear Induction Pump

This paper presents the constructional features and performance analysis of a low flow rate Annular Linear Induction Pump (ALIP) which is used for pumping liquid sodium. The performance of the pump is evaluated by means of both electrical equivalent circuit and 2-dimensional finite element method (FEM) based models. The predictions of the models are compared with experimental results. The details of the experimental set-up are also presented. Predictions are made with regard to differential pressure, input line current and input power. The effect of temperature on pump performance is also discussed. The prediction of differential pressure made by FEM model and prediction of input power by equivalent circuit based model agree fairly well with the experimental data.

Band structure engineering and reconstruction in electric circuit networks

We develop an approach to design, engineer, and measure band structures in a synthetic crystal composed of electric circuit elements. Starting from the nodal analysis of a circuit lattice in terms of currents and voltages, our Laplacian formalism for synthetic matter allows us to investigate arbitrary tight-binding models in terms of wave number resolved Laplacian eigenmodes, yielding an admittance band structure of the circuit. For illustration, we model and measure a honeycomb circuit featuring a Dirac cone admittance bulk dispersion as well as flat band admittance edge modes at its bearded and zigzag terminations. We further employ our circuit band analysis to measure a topological phase transition in the topolectrical Su-Schrieffer-Heeger circuit.

Research of the induction-dynamic mechanism operation characteristics

The design of the linear-drive induction-dynamic mechanism used in high-speed breakers is presented. The research mechanism consists of a coil with leads and a moving disk. The coil of the mechanism is wound with copper tape, the disk is made of copper bus and mounted on the rod, which passes through the hole of the coil. A circuit diagram of a laboratory test bench for the study of the induction-dynamic mechanism has been developed and the principle of operation of the circuit has been considered. A description of the electrical circuit elements is given. A prototype model of the induction-dynamic mechanism was manufactured and a mobile laboratory stand was assembled with the necessary devices mounted on a DIN-rail and ancillary accessories. The high speed of the induction-dynamic mechanism is ensured by the presence of a storage capacitor, which discharges the stored energy to the mechanism coil in a relatively short time. Auxiliary parts for mounting the elements of the stand are made using a modern 3D printer FLASHFORGE CREATOR PRO. Oscillograms of transients are obtained when an induction-dynamic mechanism is triggered, namely: oscillograms of current in the mechanism winding and of voltage on a storage capacitor as well as oscillogram of moving disk displacement. The laboratory stand is used in the educational process as a component of the laboratory workshop on the discipline "Electrical Apparatus"

The dynamics of geomagnetic substorms with the WINDMI model

The global dynamics of substorms are controlled by several key magnetospheric parameters. In this work we obtain quantitative measures of these parameters from a low-order nonlinear model of the nightside magnetosphere called WINDMI. The model uses solar wind and IMF measurements from the ACE spacecraft as input into a system of 8 nonlinear ordinary differential equations. The state variables of the differential equations represent the energy stored in the geomagnetic tail, central plasma sheet, ring current and field-aligned currents. The output from the model is the geomagnetic westward auroral electrojet (AL) index and the Dst index. Intermediate variables of the model are the plasma sheet pressure, geotail current, cross-tail electric field, parallel ion velocity and the pressure gradient current. The values of these variables are controlled by physical parameters of the model, consisting of spatially averaged quantities that are analogous to electric circuit elements. We tune the model to re-produce substorm events, comparing model capability against observations of auroral brightening and the auroral electrojet indices AL from WDC Kyoto and SML from SuperMAG. The model is capable of capturing events within a 10–12-min interval of occurrence, with level of activity comparable to the measured indices.

Hydrogen Evolution on Catalytically Active Electrodeposited Ni–Re Alloy: Electrochemical Impedance Study

Hydrogen evolution reaction on the catalytically active Ni–Re alloy is studied by the method of electrochemical impedance. The alloy was fabricated by the electrodeposition from the ammonium—citrate solutions. The experiments were performed in the 0.1 M sodium hydroxide solution. Based on the analysis of equivalent circuits, it is found that the absorption of hydrogen atoms on the Ni–Re cathode is controlled by diffusion. The parameters of structural elements of equivalent electric circuits are calculated, and the effect of cathodic overpotential on these parameters is analyzed.

Preparation of polyvinylpyrrolidone-based polymer electrolytes and their application by in-situ gelation in dye-sensitized solar cells

Polyvinylpyrrolidone (PVP), as a nitrogen-containing heterocyclic polymer, is a promising candidate for preparation of high performance iodide-based polymer electrolytes for dye-sensitized solar cells (DSSCs). In the present investigation, PVP electrolytes composed of different wt% loadings of potassium iodide and iodine were prepared, thoroughly characterized, and applied to DSSCs. The TiO2 electrode of the solid state DSSCs was optimized (film thickness, dye loading, TiCl4 treatment), to achieve high energy conversion efficiency. Differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, electrochemical impedance spectroscopy, linear sweep voltammetry, and ultraviolet–visible spectroscopy were used to characterize the PVP electrolytes. One-diode model equivalent circuit analysis was applied to DSSCs characteristic curve, in order to calculate the key electrical circuit elements values, determining solar cells efficiency. The maximum energy conversion efficiency attained by the solid state DSSCs under real test conditions was 3.74%, at about 1000 W/m2 irradiation intensity. By in-situ gelation of the PVP electrolytes onto TiO2, an optimal electrode film thickness on the order of 15 μm was achieved, which is very close to the corresponding value usually attained to liquid state DSSCs. The results are satisfactory compared to DSSCs employing liquid state factory available electrolytes, while simultaneously the PVP electrolytes preparation is simple and of low-cost, having great prospects for further optimization.

Evaluation of the limiting factors affecting large-sized, flexible, platinum-free dye-sensitized solar cells performance: a combined experimental and equivalent circuit analysis

Reducing further the cost, increasing the application range, and scaling up of dye-sensitized solar cells (DSSCs) are important issues for their wide commercialization. The present paper constitutes a comprehensive analysis of the limiting factors affecting large-sized, flexible, platinum-free DSSCs performance. The results are interpreted using a series of materials characterization techniques, including scanning electron microscopy, atomic force microscopy, X-ray diffraction, Brunauer–Emmett–Teller analysis, ultraviolet–visible spectroscopy, diffuse reflectance spectroscopy, photoluminescence analysis, and cyclic voltammetry. Equivalent circuit analysis of DSSCs was applied, in all cases, to derive the key electrical circuit elements values, determining solar cells performance. Α satisfactory energy conversion efficiency was achieved by the implementation of the novel fabricated carbon-based counter electrodes to DSSCs, equal to the corresponding obtained by the photo-electrochemical cells employing commercially available platinum-based counter electrodes. The flexible, platinum-free DSSCs demonstrated a decreased photo-generated current and electron transport kinetics, while the charge recombination rate at TiO2/electrolyte and conductive substrate/electrolyte interfaces was increased, compared to the rigid ones. The scaling up effect was intense in the flexible devices, while the area-specific total series parasitic resistance increased, at high rates, by the solar cell active area. Equivalent circuit model successfully reproduced all experimental current–voltage characteristic curves of DSSCs, revealing that it is a powerful tool for routine analysis when designing novel photo-electrochemical cells.

An efficient and reliable small signal intrinsic parameters extraction for HEMT GaN devices

AbstractTo efficiently design GaN HEMT devices, a robust extraction of their intrinsic electrical equivalent circuit element values is critical. Aiming to accurately determine all intrinsic element values, a new elements‐based small‐signal equivalent circuit technique is introduced in this paper. Compared to the conventional GaAs‐based HEMT small‐signal model composed of 16 elements, the proposed equivalent circuit consists of two parasitic distributed interelectrode extrinsic capacitances and two additional feedback intrinsic resistances. The circuit element values were obtained starting from measured S‐parameters and using Y‐matrix transformations. The efficiency of the proposed methodology was demonstrated through excellent agreement between simulated and measured data up to 60 GHz.

Electrical model of cold atmospheric plasma gun

We present an analytical model of cold atmospheric plasma formed by a dielectric barrier discharge (DBD), which is based on the lumped and distributed elements of an equivalent electric circuit of this plasma. This model is applicable for a wide range of frequencies and amplitudes of the applied voltage pulses, no matter whether or not the generated plasma plume interacts with a target. The model allows quantitative estimation of the plasma plume length and the energy delivered to the plasma. Also, the results of this model can be used for the design of DBD guns which efficiently generate cold atmospheric plasma. A comparison of the results of the model with those obtained in experiments shows a fairly good agreement.