Equivalent Parallel Resistance Research Articles

Development of planar pressure sensors based on SWCNTs and Poly(aniline)

Planar flexible pressure sensors were produced with single-walled carbon nanotubes (SWCNTs) and poly(aniline) (PANI) composite. Both materials have been processed as films from liquid suspension onto poly(ethylene) terephthalate (PET) substrate, using indium tin oxide electrodes as lateral electrodes. In this device geometry, the pressure can be applied uniformly to the sensing material, reducing its cross-sectional area, and thus increasing the electrical resistance. After pressure removal, the resistance recovers the initial value, a reversible process that can be used in cycles to monitor pressure variations in larger areas and ranges. This device presents a more linear response when compared with layered pressure sensors, where the sensitivity is commonly limited by the mechanical failure of the bottom/top electrodes. Therefore, this approach can be adapted to produce low-cost pressure sensors that allow the monitoring of larger pressure values (up to ∼ 2.2 MPa). The sensor also responds to lower pressure values being applied in punctual regions, in this case, the electrical resistance drops because the sensor responds as an equivalent parallel resistance.

Mathematical expressions for simulation of supercapacitor voltammetry curves and capacitance dependence on scan rate

A straightforward RC series circuit model was proposed to fit the cyclic voltammetry experimental data of various symmetrical electrochemical supercapacitors. The model simulated the experimental behavior for exponential dependence of capacitance on the scan rate. In this model, the zero-scan rate capacitance was considered as a constant, and the equivalent serial resistance depended on the scan rate. Neither the equivalent parallel resistance nor a possible intrinsic dependence of capacitance on applied voltage was considered in the modelling.

Non-destructive quality assessment method for Korla fragrant pears based on electrical properties and adaptive neural-fuzzy inference system

This study aimed to achieve the rapid and non-destructive quality assessment of Korla fragrant pears, thereby maximising the value of damaged pears and improving the market supply–demand balance. The electrical characteristics of damaged Korla fragrant pears were measured using a fruit electrical property detector and the trends in the quality of the fragrant pears within their shelf life were analysed. The quality of damaged Korla fragrant pears was predicted by using an adaptive neural-fuzzy inference system (ANFIS). Electrical properties were used as inputs to the system and quality was the output of the system. A total of eight functional models with different degrees of membership were constructed and the optimal one was selected. The results demonstrated that the equivalent parallel capacitance (Cp) of the damaged Korla fragrant pears increased gradually throughout their shelf life, while equivalent parallel resistance (Rp) and complex impedance (Z) decreased. Additionally, the green–red difference (a*) increased gradually, while hardness and soluble solid content (SSC) decreased continuously. Based on the combination of electrical properties and the ANFIS, gbellmf was the optimal model to determine the SSC of the damaged Korla fragrant pears (R2 = 0.9123) and gaussmf was the optimal model to determine the hardness and a* of the damaged Korla fragrant pears (R2 = 0.9112 and 0.8853, respectively). It was concluded that the combined use of electrical properties and the ANFIS method enabled the successful quality assessment of fragrant pears. This approach was conducive to facilitating the optimisation and updating of non-destructive quality assessment technologies for fragrant pears, promoting quality and efficiency improvement in the fragrant pear industry.

Global sensitivity analysis of photovoltaic cell parameters based on credibility variance

Photovoltaic cells can directly convert solar energy into electrical energy, which is environmentally friendly and has a wide range of applications. In practical engineering, the uncertainty of photovoltaic cell parameters has an important impact on cell performance. In order to study the influence of parameter uncertainty on the output performance of photovoltaic cells, a photovoltaic cell model is established and five parameters are selected: irradiation intensity, photovoltaic cell surface temperature, temperature coefficient, equivalent series resistance and equivalent parallel resistance. The influence of these parameters on the output power and conversion efficiency of photovoltaic cells is studied by using the global sensitivity analysis method based on fuzzy theory. The principal and total global sensitivity indexes describing the influence of each parameter on the output performance were therefore calculated and ranked. The key parameters influencing the performance of photovoltaic cells were determined to be related to cell surface temperature and equivalent parallel resistance. In actual production and life, the output performance of photovoltaic cells can be improved by controlling these two factors. The results of this study can help to guide the performance analysis and parameter optimization of photovoltaic cells, accelerating the development and improving the adoption of photovoltaic systems.

Modeling and Simulations in Symmetrical Supercapacitors Using Time Domain Mathematical Expressions

This study presents the deduction of time domain mathematical equations to simulate the curve of the charging process of a symmetrical electrochemical supercapacitor with activated carbon electrodes fed by a source of constant electric potential in time ε and the curve of the discharge process through two fixed resistors. The first resistor RCo is a control that aims to prevent sudden variations in the intensity of the electric current i1(t) present at the terminals of the electrochemical supercapacitor at the beginning of the charging process. The second resistor is the internal resistance RA of the ammeter used in the calculation of the intensity of the electric current i1(t) over time in the charging and discharging processes. The mathematical equations generated were based on a 2R(C + kUC(t)) electrical circuit model and allowed to simulate the effects of the potential-dependent capacitance (kUC(t)) on the charge and discharge curves and hence on the calculated values of the fixed capacitance C, the equivalent series resistance (ESR), the equivalent parallel resistance (EPR) and the electrical potential dependent capacitance index k.

A 16-Times Frequency Multiplier for 5G Synthesizer

This article presents 16-times frequency multiplier composing of two four-times frequency multipliers (quadrupler) in cascade connection. The proposed topology is new structure of tuned-frequency multiplier (TFM) for better harmonic rejection ratio (HRR) with wide frequency range and low power consumption. For accomplishing reliable output frequency band of 16–28 GHz, the whole band is divided into 64 subsidiary frequency bands by applying 6-bits digitally controlled capacitor-bank of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -tuned tank. The proposed quadrupler is consisted of a harmonic generator (HG) and a cascode <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -tuned buffer. The proposed HG topology is based on double balanced mixer (DBM). Unlike typical mixer bias, the bottom differential pair devices of the proposed HG are C-class biased to generate more desired the fourth order harmonic. In addition, to reduce power consumption and frequency conversion gain variations for the whole target frequency band, negative- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$g_{m}$ </tex-math></inline-formula> differential pair is added in parallel to enhance the equivalent parasitic parallel resistance of the HG <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -tank while keep it from oscillation. Great efforts have been contributed to minimize process variation effects by simple but relatively accurate capacitance calibration. Furthermore, each <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -tuned tank output amplitude is regulated by a loop to maintain same output swing for the best optimization of specifications such as power consumption and HRR. The proposed 16-times multiplier is fabricated on 65-nm complementary metal–oxide–semiconductor (CMOS) process and successfully tested. Chip die size 0.7 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> excluding input/output (I/O) pads and average power consumption is only 6 mW for 16–28 GHz frequency band. Also, negligible phase noise degradation is achieved.

Self-Healing Processes of Metallized Film Capacitors in Overload Modes—Part II: Theoretical and Computer Modeling

In this article, we present the theoretical models on self-healing (SH) processes in metallized film capacitors (MFCs) in overload modes. Based on the proposed dynamic model of capacitor's SH resistance, the current and voltage of MFC in SH process and the value of dissipated energy, W <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SH</sub> , can be calculated. Theoretical model of MFC degradation due to SH processes approves that in the vicinity of the breakdown places of polymer dielectric, a high SH energy leads to their carbonization. The numerous SH events result in the decreasing of the equivalent parallel resistance (EPR). An analysis of MFC electrothermal state shows that at critical values of applied voltage at 4-5 of nominal values, the dangerous local heating of the polymer dielectric can occur. Computer simulation describes the behavior of the EPR of the polymer film capacitor, which is determined by the number and intensity of SH acts. Finally, the numerical model for evaluation of the thermal state of the capacitor is offered. Numerous SH acts (especially of high SH energy level) cause the local heating of MFC section. The surface temperature of the capacitor may seem normal, though the local heating reaches the level dangerous for polymer. The analytic estimations and simulation results are in quite good agreement with experimental data.

Self-Healing Processes of Metallized Film Capacitors in Overload Modes—Part 1: Experimental Observations

Metallized film capacitors (MFCs) are used in many applications requiring high volumetric energy characteristics. Along with an increase in the dielectric permittivity of the polymer film, operating in overload mode is a simple way to dramatically increase the energy density of capacitors for relatively short periods. The unique feature of MFC, a self-healing (SH) ability, makes this possible. However, the task is complicated by the lack of information on the energy characteristics of SH in real capacitors, especially when they are voltage overstressed. Part 1 of this article contains the results of experimental investigations of SH processes in overload modes under the soft-training test. At the level of voltage up to 8 of nominal values, three types of SH were discovered: single, repetitive, and multiple. The energy characteristics of SH processes obtained in real MFCs varied widely from those in the literature data. The cumulative SH energy characteristic was introduced and proposed for diagnostic purposes. The reasons for repetitive SH were investigated and analyzed. Equivalent parallel resistance as a sensitive diagnostic parameter of the overloaded MFC was chosen and applied.

Modeling and Increasing the High-Frequency Impedance of Single-Layer Mn-Zn Ferrite Toroidal Inductors With Electromagnetic Analysis

This article first investigates the equivalent parallel capacitance (EPC) and equivalent parallel resistance (EPR) due to the electromagnetic field inside the Mn-Zn ferrite toroidal cores of the inductors with a single-layer winding based on electromagnetic theory. From the investigation, the effects of core's cross-sectional shape and number of winding turns on the EPC and EPR are explored. A stacked core structure was studied to increase the inductor's high-frequency (HF) impedance for electromagnetic interference suppression. The article further investigated the EPC due to the electric field energy in the space between winding turns, and between the winding turns and the core. The effect of the number of winding turns on total EPC was also explored. The technique to achieve high HF impedance was proposed with an optimal number of winding turns. Both simulations and experiments were conducted to validate the developed theory and techniques.

The Effect of Vacuum Annealing and HDDR Processing on the Electrochemical Characteristics of Activated Carbon and Graphene Oxide for the Production of Supercapacitors Electrodes

Electric double-layer capacitors prepared using activated carbons have been subjected to vacuum heat treatments at low and high temperatures (200, 400, 600, 800 and 1000°C). The electrodes have been tested at a potential of 1.1 V employing a KOH electrolyte (1.0and 6.0 mol.L-1). The effect of or HDDR upon the electrical properties has been investigated by cyclic voltammetry. It has been shown that the specific capacitance at 5 msV-1 increases from 50 Fg-1 to 130 Fg-1 after a heat treatment at 400°C for 1 hour under back pump vacuum. At 400°C the diminution in the specific capacitance with higher scanning rate (10 msV-1) was much less pronounced (from 130 Fg-1 to 100 Fg-1). Equivalent series resistance (ESR) and equivalent parallel resistance of supercapacitors electrodes have also been investigated. Internal resistances of the supercapacitors were calculated using the galvanostatic curves at current densities (100 mAg-1).A compositional and morphological evaluation of these electrodes showed no significant change on the activated carbon structure.

A nondestructive testing method for soluble solid content in Korla fragrant pears based on electrical properties and artificial neural network.

The detection of soluble solid content in Korla fragrant pear is a destructive and time‐consuming endeavor. In effort to remedy this, a nondestructive testing method based on electrical properties and artificial neural network was established in this study. Specifically, variations of electrical properties (e.g., equivalent parallel capacitance, quality factor, loss factor, equivalent parallel resistance, complex impedance, and equivalent parallel inductance) of Korla fragrant pears with accumulated temperature were tested using a workbench developed by ourselves. After that the characteristic variables of electrical properties were constructed by principal component analysis (PCA). In addition, three models were constructed to predict SSC in Korla fragrant pears based on the characteristic variables: general regression neural network (GRNN), back‐propagation neural network (BPNN), and adaptive network fuzzy inference system (ANFIS). The results indicated that the GRNN model has the best prediction effects of SSC (R 2 = 0.9743, RMSE = 0.2584), superior to that of the BPNN and ANFIS models. Results facilitate a successful, alternative application for rapid assessment of SSC of the maturation stage Korla fragrant pear.

Structure, electric and dielectric properties of PbFe1/3Ti1/3W1/3O3 single perovskite compound

A conventional solid-state method was used to prepare Pb(Fe1/3Ti1/3W1/3)O3 single perovskite material. The sample sintered at 900?C was studied by XRD and after Rietveld refinement the orthorhombic structure with Pbam space group was confirmed. The FTIR frequency bands corresponding to Pb-O, Ti-O, O-lattice, W- O-W and Fe-O stretching vibrations together with the XRD data also confirmed that Fe2+ and W6+ ions are incorporated in the structure and most probably substituted Ti4+ ions at the B site of the perovskite ABO3 structure. The average grain size of the perovskite ceramics, estimated from SEM micrograph, was 1 to 2 ?m. Variation of dielectric properties and AC conductivity with frequency and temperature revealed that the material had semiconducting nature and negative temperature coefficient of resistance (NTCR). The Nyquist plots were modelled with an equivalent circuit consisted of parallel capacitance, resistance and constant phase element corresponding to the grains (bulk) and grain boundaries. It was observed that grain resistance (Rb) of the sample decreases with the rise of temperature, which supports the NTCR behaviour. The semi-circular arcs of the Nyquist and Cole-Cole plots confirm the semiconducting nature of the sample.

Characteristics of Output Filters Providing Electromagnetic Compatibility of the Frequency Converter of an Electric Drive with Asynchronous Motors

An analysis of the characteristics of the output filters of electromagnetic compatibility of a frequency converter, including their logarithmic amplitude-frequency characteristics, is carried out by mathematical modeling. The filters with the different parameters, are considered in the steady operation mode at the carrier frequency of pulse-duration modulation of 2.5 kHz and basic frequency of supply voltage of the asynchronous motor of 50 Hz, including with the different connection diagrams of the damping resistors—with parallel connection of inductance in the longitudinal filter branch and series connection of the capacity in the transverse filter branch. In addition, the filter is studied, not including the damping resistors. The losses in the filters are considered. A conclusion is drawn that it is necessary to consider the parasitic parameters of the capacitors: equivalent series inductance, equivalent series resistance, equivalent parallel resistance considering the leakage current through the capacitor, and voltage regulator diode simulating the behavior of the capacitor under the overvoltages.

MWCNT–Epoxy Nanocomposite Sensors for Structural Health Monitoring

We address multi-walled carbon nanotubes (MWCNTs) for structural health monitoring in adhesive bonds, such as in building structures. MWCNT-loaded composites are employed to sense strain changes under tension load using an AC impedance measurement setup. Different weight percentages of 1, 1.5, 2 and 3 wt % MWCNTs are added to the base epoxy resin using different dispersion times, i.e., 5, 10, and 15 min. The equivalent parallel resistance of the specimens is first measured by applying an alternating voltage at different frequencies. To determine the mechanical as well as sensory properties, the specimens are then subjected to a tensile test with concurrent impedance measurement at a fixed pre-chosen frequency. Using alternating voltage, a higher sensitivity of the impedance reading can be achieved. Employing these sensors in buildings and combining the readings of a network of such devices can significantly improve the buildings’ safety. Additionally, networks of such sensors can be used to identify necessary maintenance actions and locations.

On the power handling of a high power combiner for industrial, scientific, and medical applications

In this paper a 2-way broadband power combiner that can handle up to 1 kW output power is designed and fabricated. The combiner covers the frequency range of 30 to 500 MHz, which is intended for industrial, scientific, and medical (ISM) applications. The power handling of the power combiner depends on the power handling of the components that constitute the combiner. The combiner is composed of some coaxial transmission lines and a transmission line transformer. The ferrite cores, which are used to suppress the common mode current, are one of the major limiting factors, regarding the power handling of the combiner. The power combiner is implemented with some binuclear and some stacked toroids of material 61, which is extensively used for common mode current suppression in this frequency range. As real ferrites have complex permeability, some of the input power dissipates as heat in the ferrite cores. The power dissipation due to the equivalent parallel resistance of each ferrite core is calculated. The proper operation of the high power combiner is verified by simulation of the temperature rise in the ferrite cores due to heat dissipation.

Still More on the &lt;inline-formula&gt; &lt;tex-math notation="LaTeX"&gt;$1/f^{2}$&lt;/tex-math&gt; &lt;/inline-formula&gt; Phase Noise Performance of Harmonic Oscillators

Modeling tank losses in a harmonic oscillator by means of an equivalent parallel resistance may lead to an optimistic estimate of phase noise, as recently experienced in a class-D CMOS oscillator. The discrepancy is significant if two conditions are fulfilled: The single-ended portion of the tank capacitance displays a non-negligible loss, and the loop gain of the oscillator is very large; in the latter case, a phase noise boost is likely to occur. In this brief, we derive phase noise equations that capture such behavior in a class-B oscillator, which is easier to approach than a class-D oscillator. The results, however, are (qualitatively) valid in general. Furthermore, the phase noise caused by the oscillator active core is always proportional to the phase noise caused by the tank losses independently of the amount of phase noise boost. The agreement between theoretical and simulation results is excellent.

Rapid on-line non-destructive detection of the moisture content of corn ear by bioelectrical impedance spectroscopy

Moisture content of corn directly affects its quality and storage time, and the rapid on-line detection of the moisture content of corn ears not threshed or in vivo in the fields is required. Because of the special shape of corn ear, the rapid, low cost and non-destructive bioelectrical impedance measurement is more suitable for its moisture content detection. Using the four-electrode method with the Agilent E4980A precision LCR meter, the electrical impedance spectroscopies of the sweet corn ears and waxy corn ears at different moisture contents were acquired. The frequency range of the detection was from 20 Hz to 2 MHz and to enhance the contact, the attached-type electrodes were wrapped in cotton soaked with 0.1% NaCl solution. The impedance data over the frequency range from 300 Hz to 5 kHz were used to obtain the parameters of the bio-impedance Cole-Cole model. The results showed a good linear correlation (coefficient of determination R2=0.960) between the equivalent parallel resistance R∞ of sweet corn ear and the moisture content value determined by standard chemical method. The research proved that the bioelectrical impedance spectroscopy can be used for detecting the moisture content of corn ear. Keywords: moisture content, non-destructive detection, bioelectrical impedance spectroscopy, corn ear DOI: 10.3965/j.ijabe.20150806.1238 Citation: Zhao P F, Zhang H L, Zhao D J, Wang Z J, Fan L F, Huang L, et al. Rapid on-line non-destructive detection of the moisture content of corn ear by bioelectrical impedance spectroscopy. Int J Agric & Biol Eng, 2015; 8(6): 37－45.

Study of Multilevel High-Resistance States in HfO&lt;sub&gt;&lt;italic&gt;x&lt;/italic&gt;&lt;/sub&gt;-Based Resistive Switching Random Access Memory by Impedance Spectroscopy

Multilevel high-resistance states are achieved in TiN/HfO x /Pt resistive switching random access memory device by controlling the reset stop voltage. Impedance spectroscopy is used to study the multilevel high-resistance states. It is shown that the high-resistance states can be described with an equivalent circuit consisting of the major components $R_{s}$ , $R$ , and $C$ corresponding to the series resistance of the TiON interfacial layer, the equivalent parallel resistance, and capacitance of the leakage gap between the TiON layer and the residual conductive filament, respectively. These components show a strong dependence on the stop voltage, which can be explained in the framework of oxygen vacancy model and conductive filament concept. On the other hand, $R$ is observed to decrease with dc bias, which can be attributed to the barrier lowering effect of the Coulombic trap well in the Poole–Frenkel emission model.

Analysis and Design of ITER 1 MV Core Snubber

The core snubber, as a passive protection device, can suppress arc current and absorb stored energy in stray capacitance during the electrical breakdown in accelerating electrodes of ITER NBI. In order to design the core snubber of ITER, the control parameters of the arc peak current have been firstly analyzed by the Fink-Baker-Owren (FBO) method, which are used for designing the DIIID 100 kV snubber. The B-H curve can be derived from the measured voltage and current waveforms, and the hysteresis loss of the core snubber can be derived using the revised parallelogram method. The core snubber can be a simplified representation as an equivalent parallel resistance and inductance, which has been neglected by the FBO method. A simulation code including the parallel equivalent resistance and inductance has been set up. The simulation and experiments result in dramatically large arc shorting currents due to the parallel inductance effect. The case shows that the core snubber utilizing the FBO method gives more compact design.

Optoelectronic properties of RNA–polyaniline–dendritic gold nanobiocomposite

The in situ reduction of Au+++ by aniline in the presence of RNA produces dendritic Au nanoparticles (AuNP) with the concomitant formation of doped polyaniline (PANI). FT-IR spectra indicate that the dendritic AuNPs are stabilized from the complexation of nitrogen atoms of quinonoid structure of PANI with the adsorbed Au+++ on it. CD spectrum indicates a small distortion of RNA ‘A’ helix toward ‘B’ helix. RNA–PANI–Au nanocomposite shows emission peak at 408nm with an additional peak at 579nm for the Forster resonance energy transfer (FRET) of PANI excitons to surface plasmon band of Au nanocrystals. The dendritic RNA–PANI–Au nanocomposite has three orders higher dc-conductivity compared to the spherical PANI–Au composite. Impedance data suggest that the system behaves as an equivalent parallel resistance–capacitance (R–C) circuit. The frequency dependency of ac-conductivity indicates three regions of conduction: at low frequency predominantly intrachain conduction by polarons of doped PANI, at medium frequency hopping of polarons through RNA and AuNP along with the intra-chain conduction and at very high frequency the conductivity is predominantly interchain due to localized hopping.