Capacitive Components Research Articles

Physical Properties of a Low-Power Helicon Source Operating on a High-Frequency Discharge with a Capacitive Component

The results of an experimental study of a low-power RF plasma source placed in a longitudinal magnetic field (helicon thruster), when it operates on a capacitive RF discharge and inductive RF discharges with a capacitive component, are presented. A significant dependence of the characteristics of the ion and electron fluxes of the source on the induction of a constant magnetic field is shown. The fundamental applicability of capacitive RF discharge as a working process in the studied plasma source is demonstrated. It is shown that the increase in the average energy of ions in the flow at the outlet of the source with the appearance of the capacitive component of the discharge is slight.

Physical Properties of a Low-Power Helicon Source Operating on a High-Frequency Discharge with a Capacitive Component

Physical Properties of a Low-Power Helicon Source Operating on a High-Frequency Discharge with a Capacitive Component

Equivalent circuit model of GaN high electron mobility transistor with consideration of non-ideal effects using genetic algorithm

This work proposes a semi-physical equivalent circuit model for GaN-based high electron mobility transistors (GaN HEMTs), taking into account the non-ideal effects of both the current source and resistance–capacitance components. The current source model is built based on both device operation and multiple model interfaces setup for important non-ideal effects, such as self-heating effects, channel length modulation, short channel effects, and so on. Moreover, according to the improved Meyer capacitance model with fringe capacitances, the non-linear capacitances of the GaN HEMT are modeled with a dependence on the bias voltages and gate geometry. The extraction of the model parameters is implemented accurately and efficiently in MATLAB through a genetic algorithm. Moreover, the capacitance model is established to be mathematically simple and Simulation Program with Integrated Circuit Emphasis (SPICE)-compatible for the design of GaN-based integrated circuits (ICs). The static and dynamic characteristics of GaN ICs were simulated and found to be in excellent agreement with the experimental results, validating that the established and well-packaged equivalent circuit model can be of great help to GaN HEMT development and IC design.

An innovative method and a medical screening device for cancer detection in real-time

Histopathology is the main technique to assess the presence of cancer cells in biopsy material and for the evaluation of positive resection margins, but it is not real-time. Older methods to assess resection margin intraoperatively are either time-consuming or exhibit a low accuracy. More recent imaging techniques have various drawbacks, like the need for exogenous contrast agents or excessive time to assess the entire resection surface or a low diagnostic performance in detecting certain types of cancer. The purpose of the current research work is the development of a medical screening device for cancer cells detection with very high accuracy and selectivity, based on a newly developed method in order to experimentally measure in real-time the excitation response of the charged elements of the biological tissue under study to the applied alternative electrical field, over a wide range of frequency spectra. The aim of this study is to present an innovative method and results from a prototype medical screening device, which allows the selective and “real-time” detection of cancer cells of any type among normal cells in any tissue type. The innovation of the proposed method lies in the view of the cell membrane emulation as an electrical circuit and also in the ability to experimentally measure in real-time the excitation response of the charged elements of the biological tissue under studies like ions, interfaces or dipoles to the applied alternative electrical field, over a wide range of frequency spectra according to the dielectric spectroscopy method. The ions can very easily follow the variations of the applied alternating electric field moving along the dynamic lines of the field. In contrast, the incapability of the abnormal neoplastic cellular formations to follow the frequency changes causes them to perform dipole oscillation instead of moving along the dynamic lines of the field. This experimentally appears as a significant increase of the capacitive component contribution to the total impedance of the tissue, relative to the purely electrical resistance contribution of the ions. A model, backed by the relevant mathematical equations, has been developed to integrate the unknown impedance of both the tissue under assessment and the interdigital micro-sensor with the known complex impedance of the data acquisition system. The ability to selectively detect cancer cells has an obvious interest and various applications in cancer diagnosis and therapy.

Impedance responses and size-dependent resonances in topolectrical circuits via the method of images

Resonances in an electric circuit occur when capacitive and inductive components are present together. Such resonances appear in admittance measurements depending on the circuit's parameters and the driving AC frequency. In this study, we analyze the impedance characteristics of nontrivial topolectrical circuits such as one- and two-dimensional Su-Schrieffer-Heeger circuits and reveal that size-dependent anomalous impedance resonances inevitably arise in finite $LC$ circuits. Through the method of images, we study how resonance modes in a multidimensional circuit array can be nontrivially modified by the reflection and interference of current from the structure and boundaries of the lattice. We derive analytic expressions for the impedance across two corner nodes of various lattice networks with homogeneous and heterogeneous circuit elements. We also derive the irregular dependency of the impedance resonance on the lattice size, and provide integral and dimensionally reduced expressions for the impedance in three dimensions and above.

Synthesis and electrical characterizations of (Sn0.8Ti0.2)O2 electronic material

ABSTRACT The ceramic composite electronic material of (Sn0.8Ti0.2)O2 has been synthesized through a cost-effective solid-state ceramic approach. The crystallographic tetragonal structure from the XRD spectrum, hydrophilic porous structure from SEM micrograph, dielectric, conductivity, and electrical modulus in addition to impedance spectroscopy over an extensive range of temperature and frequency have been elucidated. Hydrophilicity, superior dielectric response with significantly low dielectric loss, and enhanced capacitive behaviour draw the major attraction of this ceramic-based material system. The temperature-dependent conductivity spectrum evinces Arrhenius’s behaviour. The grain and grain boundary effects in the synthesized sample has been displayed through the Nyquist spectrum. The non-Debye type of relaxation mechanism has been established through an electric modulus study. The extensive study sketched out this composite as a potential capacitive electronic component for humidity sensor device applications. The investigated electrical parameters associated with the ceramic composite may enlighten the development of functional electronic devices.

Alignment-free twisted-split-ring metasurface on single substrate with 2π phase range for linearly polarized sub-terahertz wave.

To achieve high-speed, large-capacity communication, next-generation mobile communication systems will require manipulation of the propagation of sub-terahertz waves in the propagation channel. In this paper, we propose the use of a novel split-ring resonator (SRR) structure as a metasurface unit cell for manipulating the linearly polarized incident and transmission waves used in mobile communication systems. In this SRR structure, the gap is twisted by 90° to efficiently use cross-polarized scattered waves. By changing the twist direction and gap size of the unit cell, 2π phase designability can be achieved, which enables linear polarization conversion efficiencies of -2 dB with a backside polarizer and -0.2 dB with two polarizers. In addition, a complementary pattern of the unit cell was fabricated, and a measured conversion efficiency of more than -1 dB at the peak with only the backside polarizer on a single substrate was verified. In the proposed structure, the 2π phase designability and efficiency gain are obtained independently by the unit cell and polarizer, respectively, thus enabling alignment-free characteristics, which are highly advantageous from an industrial viewpoint. Metasurface lenses with binary phase profiles of 0 and π were fabricated using the proposed structure with a backside polarizer on a single substrate. The lenses' focusing, deflection, and collimation operations were experimentally verified with a lens gain of 20.8 dB, which agreed well with our calculated results. Our metasurface lens has the great advantages of easy fabrication and implementation, and it has the potential to enable dynamic control by combining it with active devices because of the simple design methodology, which entails only changing the twist direction and the gap's capacitance component.

Synthesis of Wideband Cross-Coupled Resonator Filter for Direct Circuit Implementation Using Lumped Elements

A synthesis method of wideband cross-coupled resonator filter with inductive and capacitive coupling components is presented using similarity transformation. The synthesized admittance matrix can fully represent the frequency-dependent characteristics of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$J$</tex-math> </inline-formula> -inverters that are used to implement the coupling components. All negative inductive-coupling elements obtained from the conventional wideband filter synthesis method can be transformed to positive capacitive coupling elements by solving the equation derived from similarity transformation, so that the resulted admittance matrix can be directly implemented using lumped elements. All values of the lumped elements can be calculated without any optimization. A third-order triplet with fractional bandwidth (FBW) of 50% and one transmission zero (TZ) in the lower stopband and a fourth-order quadruplet with FBW of 50% and two symmetric TZs are synthesized to demonstrate the proposed method.

Effect of Space Charge on Stationary and Transient Electric Field Distribution of HVDC Cable Joint

The conversion of AC XLPE cable lines into direct-current (DC) operation has been proven to be an effective means to improve the transmission capacity of the system. Prefabricated joints are the weakest points of a cable line because of the complex structures, and composite interfaces contained. Therefore, it is of great theoretical and engineering significance to study the field strength distribution of XLPE AC cable prefabricated joints under DC voltage, effectively evaluate their DC tolerance characteristics, and provide a basis for the construction and transformation of XLPE cable DC distribution network system. This paper takes the silicone rubber (SIR), and ethylene-propylene-diene monomer (EPDM) prefabricated joints of 10kV XLPE cables as an example, the cable joint temperature field, and electric field coupling simulation model is established by the finite element analysis software COMSOL Multiphysics. The steady and transient electric field simulation of the joints under different DC voltages and load conditions are carried out considering the influence of space charge. The results show that with the increase of applied voltages and load level, the space charge injection increases, and the maximum steady state field strength in the joint is concentrated at the root of the stress cone, showing an increasing trend. Compared with the SIR joint, the field strength in the EPDM joint is higher. The capacitive component of the field strength in the joint is proportional to the peak value of the impulse voltage under the DC superimposed impulse voltage. In other words, the transient electric field equation meets the superposition principle applied.

Elucidating d-[formula omitted] conjugated two-dimensional 2,3,6,7,10,11-hexahydroxytriphenylene based conductive metal-organic framework for hybrid supercapacitors

Electrochemical energy technology demands highly proficient and stable systems which ultimately rely upon the discovery and development of promising electrode materials. Here, we report a two-dimensional conductive nickel- metal organic framework (Ni-MOF) for energy storage application. A novel Ni- based MOF was synthesized by utilizing a distinctive ligand 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP termed as Ni3(HHTP)2. The highly conductive, porous and stable two dimensional π-conjugated structure of HHTP makes Ni3(HHTP)2 an auspicious contender for energy storage applications. We characterize the Ni3(HHTP)2 developed through hydrothermal route for its structural properties and then explore its energy storage profile by fabricating the hybrid energy storage device. The Ni3(HHTP)2 based asymmetric device exhibits the capacity of 194 C/g providing the energy (Es) and power density (Ps) of 43 Wh/kg and 2400 W/kg, respectively. We then scrutinize its capacitive and diffusive components by calculating regression parameters k1 and k2 using Dunn’s model to bring further insight into the electrochemical characteristics of the electrode material. Ni3(HHTP)2 is an appealing member of 2D conductive MOFs to utilize for energy storage applications.

Modelling the lumped parameter network of a power transformer using sweep frequency response analysis

ABSTRACT Accurate modelling of power transformers is beneficial for fault diagnosis and the health condition assessment of the power transformers. However, measuring the internal parameters of power transformers while they are in operation is not feasible due to the costs involved in interrupting the power supply and dismantling the components. To address this issue, this paper proposes a new method that uses artificial neural networks and genetic algorithms to synthesise the power transformer lumped parameter network based on the frequency response. The proposed methodology can be utilised to model power transformers and obtain lumped parameter values with minimal cost and time. A physically realisable transfer function derived using the sweep frequency response test data of a power transformer is the input of the proposed model. The combined approach of an artificial neural network and genetic algorithms generates the output as resistive, inductive, and capacitive components of the lumped parameter circuit of power transformers. Furthermore, the entire approach is explained using a case study and validated by means of error analysis. The proposed method is an easy-to-implement process to develop in a computer program that can be used effectively for accurate fault identification in power transformers and health assessments.

Design and analysis for the SPICE parameters of waveform-selective metasurfaces varying with the incident pulse width at a constant oscillation frequency

In this study, we numerically demonstrate how the response of recently reported circuit-based metasurfaces is characterized by their circuit parameters. These metasurfaces, which include a set of four diodes as a full wave rectifier, are capable of sensing different waves even at the same frequency in response to the incident waveform, or more specifically the pulse width. This study reveals the relationship between the electromagnetic response of such waveform-selective metasurfaces and the SPICE parameters of the diodes used. In particular, we draw conclusions about how the SPICE parameters are related to (1) the high-frequency operation, (2) input power requirement and (3) dynamic range of waveform-selective metasurfaces with supporting simulation results. First, we show that reducing a parasitic capacitive component of the diodes is important for realization of the waveform-selective metasurfaces in a higher frequency regime. Second, we report that the operating power level is closely related to the saturation current and the breakdown voltage of the diodes. Moreover, the operating power range is found to be broadened by introducing an additional resistor into the inside of the diode bridge. Our study is expected to provide design guidelines for circuit-based waveform-selective metasurfaces to select/fabricate optimal diodes and enhance the waveform-selective performance at the target frequency and power level. Our results are usefully exploited to ensure the selectivity based on the pulse duration of the incident wave in a range of potential applications including electromagnetic interference, wireless power transfer, antenna design, wireless communications, and sensing.

DC fault detection in hybrid MTDC systems using transient average of DC reactor voltage

The existence of various types of converters makes the fault characteristics of the hybrid multi-terminal DC (MTDC) system more complicated than the voltage source converter-based (VSC-based) MTDC system. A reduced line commutated converter (LCC) model for DC fault analysis is first proposed in this paper, where the LCC-based rectifier with control effects is regarded as an equivalent RLC circuit. By neglecting the resistive and capacitive components in the high-frequency domain, the original network analysis is significantly simplified to derive concise time-domain expressions of the initial DC fault current. On top of this, a single-terminal DC fault detection scheme using the transient average of DC reactor voltage is designed for the hybrid MTDC system. The thresholds for detecting faults on the LCC-connected and VSC-connected lines are calculated based on the derived fault current expressions, respectively. Simulation studies based on PSCAD/EMTDC have validated the proposed fault analysis model is accurate within the initial period after fault, while the proposed fault detection scheme for hybrid MTDC systems is fast, sensitive, and tolerant to high fault resistances.

변형된 접지면 구조를 이용한 대역폭 확장 특성을 갖는 보우-타이형 준-야기 안테나

In this paper, a bow-tie quasi-Yagi antenna with a modified ground plane structure is proposed for wideband characteristics. The ground plane structure of the proposed antenna improved the impedance-matching characteristics by inserting a parallel plate ground with a width equal to the parallel-coupled feed line width. This simply modified ground plane structure can lead to an improvement in impedance matching by additional inductance, capacitance, mutual inductance, and mutual capacitance components. The proposed antenna has a −10-dB reflection coefficient fractional bandwidth of 30 % and a realized gain of 7.7 dBi at the center frequency.

Seeing beyond the spikes: reconstructing the complete spatiotemporal membrane potential distribution from paired intra- and extracellular recordings.

Although electrophysiologists have been recording intracellular neural activity routinely ever since the ground-breaking work of Hodgkin and Huxley, and extracellular multichannel electrodes have also been used frequently and extensively, a practical experimental method to track changes in membrane potential along a complete single neuron is still lacking. Instead of obtaining multiple intracellular measurements on the same neuron, we propose an alternative method by combining single-channel somatic patch-clamp and multichannel extracellular potential recordings. In this work, we show that it is possible to reconstruct the complete spatiotemporal distribution of the membrane potential of a single neuron with the spatial resolution of an extracellular probe during action potential generation. Moreover, the reconstruction of the membrane potential allows us to distinguish between the two major but previously hidden components of the current source density (CSD) distribution: the resistive and the capacitive currents. This distinction provides a clue to the clear interpretation of the CSD analysis, because the resistive component corresponds to transmembrane ionic currents (all the synaptic, voltage-sensitive and passive currents), whereas capacitive currents are considered to be the main contributors of counter-currents. We validate our model-based reconstruction approach on simulations and demonstrate its application to experimental data obtained in vitro via paired extracellular and intracellular recordings from a single pyramidal cell of the rat hippocampus. In perspective, the estimation of the spatial distribution of resistive membrane currents makes it possible to distiguish between active and passive sinks and sources of the CSD map and the localization of the synaptic input currents, which make the neuron fire. KEY POINTS: A new computational method is introduced to calculate the unbiased current source density distribution on a single neuron with known morphology. The relationship between extracellular and intracellular electric potential is determined via mathematical formalism, and a new reconstruction method is applied to reveal the full spatiotemporal distribution of the membrane potential and the resistive and capacitive current components. The new reconstruction method was validated on simulations. Simultaneous and colocalized whole-cell patch-clamp and multichannel silicon probe recordings were performed from the same pyramidal neuron in the rat hippocampal CA1 region, in vitro. The method was applied in experimental measurements and returned precise and distinctive characteristics of various intracellular phenomena, such as action potential generation, signal back-propagation and the initial dendritic depolarization preceding the somatic action potential.

Frequency Response Analysis for Three-Phase Star and Delta Induction Motors: Pattern Recognition and Fault Analysis Using Statistical Indicators

This paper presents a new investigation to detect various faults within the three-phase star and delta induction motors (IMs) using a frequency response analysis (FRA). In this regard, experimental measurements using FRA are performed on three IMs of ratings 1 HP, 3 HP and 5.5 HP in normal conditions, short-circuit fault (SC) and open-circuit fault (OC) conditions. The SC and OC faults are applied artificially between the turns (Turn-to-Turn), between the coils (Coil-to-Coil) and between the phases (Phase-to-Phase). The obtained measurements show that the star and delta IMs result in dissimilar FRA signatures for the normal and faulty windings. Various statistical indicators are used to quantify the deviations between the normal and faulty FRA signatures. The calculation is performed in three frequency ranges: low, middle and high ones, as the winding parameters including resistive, inductive and capacitive components dominate the frequency characteristics at different frequency ranges. Consequently, it is proposed that the boundaries for the used indicators facilitate fault identification and quantification.

Wireless batteryless soft sensors for ambulatory cardiovascular health monitoring

Seismocardiography (SCG) is the measure of local vibrations in the chest due to heartbeats. Typically, SCG signals are measured using rigid integrated circuit (IC) accelerometers and bulky electronics. However, as alternatives, recent studies of emerging flexible sensors show promise. Here, we introduce the development of wireless soft capacitive sensors that require no battery or rigid IC components for measuring SCG signals for cardiovascular health monitoring. Both the capacitive and inductive components of the circuit are patterned with laser micromachining of a polyimide-coated copper and are encapsulated with an elastomer. The wearable soft sensor can detect small strain changes on the skin, which is wirelessly measured by examining the power reflected from the antenna at a stimulating frequency. The performance of the device is verified by comparing the fiducial points to SCG measured by a commercial accelerometer and electromyograms from a commercial electrode. Overall, the human subject study demonstrates that the fiducial points are consistent with data from commercial devices, showing the potential of the ultrathin soft sensors for ambulatory cardiovascular monitoring without bulky electronics and rigid components.

Dual‐Mode Pressure Sensor Integrated with Deep Learning Algorithm for Joint State Monitoring in Tennis Motion

The precise capture and identification of movement features are important for numerous scientific endeavors. In this work, we present a novel multimodal sensor, called the resistance/capacitance dual‐mode (RCDM) sensor, which effectively differentiates between compression and stretchable strains during tennis motion; meanwhile, it can also accurately identify various joint movements. The proposed wearable device features a seamless design, comprising two separate components: a resistive part and a capacitive part. The resistive and capacitive components operate independently and utilize a resistance–capacitance mechanism to measure pressure and strain signals, respectively. The RCDM sensor demonstrates remarkable sensitivity to strains (GF = 7.84, 0%–140%) and exceptional linear sensitivity (S = 4.08 kPa−1) through capacitance. Utilizing machine learning algorithms, the sensor achieves a recognition rate of 97.21% in identifying various joint movement patterns. This advanced production method makes it feasible to manufacture the sensors on a large scale, offering tremendous potential for various applications, including tennis sports systems.

Small-Signal Stability of DC Current Flow Controller Integrated Meshed Multi-Terminal HVDC System

In this paper, the small-signal stability of a DC current flow controller (CFC) integrated meshed multi-terminal HVDC (MTDC) system is investigated with unique contributions: (1) The dynamics of a multi-line CFC, interconnected voltage- source converters (VSCs) and the DC transmission lines are considered in the small-signal modelling. (2) The switching effect of the capacitive components in the π-type DC transmission lines is identified. The comparative studies of modelling the DC transmission lines using π-type/T-type equivalent circuit are conducted. (3) The impact of the CFC on the AC side of the MTDC system is taken into account with analysis of the critical short-circuit ratio (CSCR) through root-locus analysis and participation factors. The relationship of the SCR with VSC outer-loop control and power transfer is analyzed. (4) The influence of the CFC control system/structural parameters on the small-signal stability of the entire system is investigated. The relationship of the CFC integration with the VSC outer-loop control is analyzed. The adjustment of single/multiple parameters for enhancing the system stability and a sequential parameter tuning approach for multiple parameters are explained. The effectiveness of the proposed method applied in different MTDC systems with CFC is verified. It would be useful for the configuration and parametric design of the CFC integrated meshed MTDC systems.

Floating Fin Shaped Stacked Nanosheet MOSFET for Low Power Logic Application

In this paper, floating fin structured vertically stacked nanosheet gate-all-around (GAA) metal oxide semiconductor field-effect transistor (FNS) is proposed for low power logic device applications. To verify the electrical performance of the proposed device, three-dimensional (3-D) technology computer-aided design (TCAD) device/circuit simulations are performed with calibrated device model parameters. As a result, it is found that gate propagation delay (tdelay) and dynamic power (Pdyn) are improved by 8% and 19%. respectively as compared to conventional vertically stacked lateral nanosheet (LNS). Through the rigorous analysis on the resistance and capacitance components of FNS and LNS, it is clearly revealed that the τdelay and Pdyn are improved at the same Pdyn (50 μW) and tdelay (187 GHz) by the reduced effective capacitance which results from the diminished gate-to-sorece/drain overlap area. Based on the TCAD simulation studies, it is expected that the FNS is suitable for next generation logic digital applications.