Equivalent Circuit Resistance Research Articles

Mixed Electric Field of Multi-Shaft Ship Based on Oxygen Mass Transfer Process under Turbulent Conditions

The theoretical basis for a multi-physics coupling modeling involving a turbulence flow field and a ship’s electric field was analyzed using the principles of electrochemistry and hydrodynamics. Considering the mass transfer of oxygen in the cathode reaction of electrochemical corrosion, the boundary element method was adopted to construct a corrosion electric field model for a multi-shaft ship under navigation. After dissecting the equivalent circuit resistance of the mechanical structure of a ship’s shaft, the initial phase difference of the equivalent resistance between different shafting systems of a multi-shaft ship was analyzed to reveal the regularity of variation of the ship corrosion mixed electric field, when the contact positions of the shaft grounding device were different. A ship model experiment was conducted to verify the correctness of the simulation model. As shown in the results, when the initial phase difference of two-shaft ship shafting equivalent resistance increased from 0° to 45°, 90°, 135°, and 180°, the amplitude of the ship’s mixed electric field varied by less than 3.7%, which was practically negligible. However, the amplitude of the ship’s shaft-rate electric field decreased by 8.30%, 25.4%, 50.2%, and 88.0%, respectively. Moreover, the minimum value of the shaft-rate electric field accounted for 4.11% of the maximum value. This significantly increased the difficulty of marine target detection based on electric field sensors.

The Characterization of the Electric Double-Layer Capacitor (EDLC) Using Python/MATLAB/Simulink (PMS)-Hybrid Model

This paper investigates the characterization of an electric double-layer capacitor (EDLC). In this study, the 300 F and 400 F EDLC supercapacitors are connected in a circuit in a laboratory experiment to produce their charge/discharge profiles at a constant current. The acquired charge/discharge profiles were used to determine the mathematical parameters of the EDLCs using the “Faranda model”, or “two-branch model”, of the EDLC. The parameters extracted from the equivalent circuit model were then used as inputs to a designed Python/MATLAB/Simulink (PMS)-hybrid model of an EDLC. This was simulated to obtain charge/discharge profiles. The resulting experimental- and simulated-charge/discharge profiles of the EDLCs were compared with each other, by superimposing their profiles to determine the accuracy of the PMS model. The PMS model was found to be very accurate. The innovation of this work lies in modeling a supercapacitor, mostly in the Python programming language in combination with a MATLAB/Simulink model. The experimental-charge/discharge profiles obtained were used to calculate the equivalent circuit resistance (ESR) and the capacitance of the EDLCs, which were compared with the existing datasheet values of the EDLCs. The characterization of the EDLC supercapacitor was done to derive a flexible PMS model of the EDLC, which can be used in a microgrid hybrid energy-storage system (HESS) to show the potential of the EDLC in improving battery lifespan.

Characteristics of discharge and beyond extreme ultraviolet spectra of laser induced discharge gadolinium plasma

The gadolinium (Gd) plasma is a potential beyond-EUV (BEUV) source for the extension of extreme ultraviolet lithography at 13.5 nm. A laser induced discharge plasma (LDP) is an effective way to excite the target material into high temperature plasma. A pulsed CO2 laser ablates a Gd plate cathode and produces an initial plasma, triggers a discharge between a Gd plate cathode and a stainless-steel cone anode, the current produces high temperature discharge plasma and creates an environment for BEUV radiation. A RLC model is used to estimate the equivalent circuit resistance and inductance, the resistance is about 0.70–0.75 Ω and the inductance is about 2.3–2.4 μH. A grazing incident ultraviolet spectrometer is established to study the Gd plasma’s BEUV radiation. With the laser energy above 120 mJ and voltage above 6.7 kV, Gd plasma spectra near the 6.7 nm is obtained. It is found that the relative spectral intensity increases and the peak of emission moves to a shorter wavelength corresponding to a higher voltage and laser energy. An atomic code combined with a simplified collisional-radiative model is used to calculate the theoretical spectra and estimate the electron temperature and density range of the LDP plasma.

High Proton Conducting Polymer Blend Electrolytes Based on Chitosan:Dextran with Constant Specific Capacitance and Energy Density.

Polymer blend electrolytes based on chitosan: dextran (CS:Dext) incorporated with various amounts of ammonium fluoride (NH4F) with constant specific capacitance (12.4 F/g) and energy density over 100 cycles were prepared using a solution cast technique. The blend electrolyte samples exhibit broader amorphous humps in X-ray diffraction (XRD) spectra compared to pure CS:Dext film. The Fourier transform infrared (FTIR) study indicates the complex formation of the added ammonium salt with the polymer blend functional groups through the shifting and decrease in the intensity of FTIR bands. The impedance plots were used to determine the conductivity of the samples. The field emission scanning electron microscopy (FESEM) images support the conductivity behavior of the samples. The impedance plots were applied in the determination of the conductivity of the samples in which the relatively highest conductivity was gained to be 1 × 10−3 S/cm. The transference number measurement (TNM) of the conducting electrolyte was 0.88, which portrays the dominancy of ion in the conduction process. Linear sweep voltammetry (LSV) verified the chemical stability and showed it to be 1.7 V and an effective electrical double layer capacitor (EDLC) that is applicable in electrochemical devices. The performance of the EDLC cell was examined using both cyclic voltammetry and constant current charge–discharge techniques at ambient temperature. The semi-rectangular shape of the cyclic voltammetry (CV) plot and no redox peak was observed. The charge-discharge process of the fabricated EDLC is durable over 100 cycles with an equivalent circuit resistance and power density of 194.5 Ω and 428 W/kg, respectively. Two main outcomes, the specific capacitance and energy densities of 12.4 Farad/g and 1.4 Wh/kg, respectively, are almost constant over 100 cycles.

Electric Solid Propellant Ablation in an Arc Discharge

Electric solid propellants are advanced solid chemical rocket propellants that can be controlled (ignited, throttled, and extinguished) through the application and removal of an electric current. Electric solid propellants are also being considered for pulsed arc ablation electric thrusters, such as the pulsed plasma thruster. The focus of this work is the electrical and ablation characteristics of electric solid propellant within an arc discharge. Arc discharges of 5–20 J per pulse were created within a cylindrical cavity, and results for the electric solid propellant are compared with polytetrafluoroethylene (PTFE), which is a traditional propellant in ablative pulsed plasma thrusters. The data indicate that the electric solid propellant has higher specific ablation per pulse () relative to PTFE (), which quantitatively agrees with an ablation energy balance model. For both propellants, the equivalent circuit resistance and inductance of the plasma arc are 50 mΩ and 125 nH, respectively. Analyses are presented indicating that the physics of propellant ablation is similar for both propellants with the differences in the observed specific ablation owing to differences in the thermodynamic properties between propellants.

Reducing impedance to ionic flux in capacitive deionization with Bi-tortuous activated carbon electrodes coated with asymmetrically charged polyelectrolytes

Capacitive deionization (CDI) with electric double layers is an electrochemical desalination technology in which porous carbon electrodes are polarized to reversibly store ions. Planar composite CDI electrodes exhibit poor energetic performance due the resistance associated with salt depletion and tortuous diffusion in the macroporous structure. In this work, we investigate the impact of bi-tortuosity on desalination performance by etching macroporous patterns along the length of activated carbon porous electrodes in a flow-by CDI architecture. Capacitive electrodes were also coated with thin asymmetrically charged polyelectrolytes to improve ion-selectivity while maintaining the bitortuous macroporous channels. Under constant current operation, the equivalent circuit resistance in CDI cells operating with bi-tortuous electrodes was approximately 2.2 times less than a control cell with unpatterned electrodes, leading to significant increases in working capacitance (20–22 to 26.7–27.8 F g−1), round-trip efficiency (52–71 to 71–80%), and charge efficiency (33–59 to 35–67%). Improvements in these key performance indicators also translated to enhanced salt adsorption capacity, rate, and most importantly, the thermodynamic efficiency of salt separation (1.0–2.0 to 2.2–4.1%). These findings demonstrate that the use of bi-tortuous electrodes is a novel approach of reducing impedance to ionic flux in CDI.

Using acoustic wave sensors to follow milk coagulation and to separate the cheeses according to the milk origin

Optimum coagulation temperature and cutting time are usually empirically defined. The use of inexpensive acoustic wave sensors to monitor milk coagulation allows monitoring the process in real time, since its early stages. Besides, data are collected with minimum disturbance, which is an advantage over other methodologies, namely rheology.Coagulation of milk was followed by measuring both the frequency and equivalent circuit resistance of a piezoelectric quartz crystal. Three types of milk, ewe, goat and cow, were coagulated using different rennets at three different temperatures. Maximum observed coagulation rate, either with plant or animal rennet, increased with temperature both for ewe and goat milk. Maximum coagulation rate was higher with plant rennet than with animal rennet at 25°C and 32°C, while the opposite was found at 50°C. The time needed to attain maximum coagulation rate was always smaller with ewe's milk than with goat's milk, and maximum coagulation rate was higher with the former. Cow's milk was much more difficult to coagulate and needed twice the rennet quantity used for ewe and goat milk.Cheese obtained with the mentioned types of milk and different rennets shows different flavours, usually perceived by experts and connoisseurs, and that an electronic nose built in our laboratory was also able to distinguish. One sensor was enough to separate cheeses made from cow, ewe and goat milk. Besides, the addition of a second sensor allowed to separate the cheeses by rennet among the ones produced with the same milk.

A full voltage-controlled nanoelectrospray system and its steady characteristic analysed by empirically equivalent circuit method

Nanoelectrospray technique, or electrohydrodynamic spraying, has been utilised in wide applications including mass spectrometry, microcolloid thrusters and micro/nano-fabrication areas. In this article, a nanoelectrospray system was developed in a pure voltage-controlled fashion with low flow rates of nL/min. Electrospray occurs by applying a voltage to overcome surface tension of the liquid without auxiliary backpressure. Pronounced increase of current with applied voltage was revealed during the pressure-free spray. In the steady spray regime a linear correlation between current and voltage was clearly identified; this can be attributed directly to the unforced electrospray where the spray properties are uniquely dictated by the voltage. This behaviour may be captured by an equivalent circuit method based upon empirical results. The equivalent circuit resistance, derived from the best-fit model, represents an electrical equivalence of the gap between the nozzle and the collector; this resistance strongly depends on both the nozzle size and the spray distance. The suitability of an electrical equivalent is further confirmed by incorporating a series resistor. No obvious difference can be distinguished electrically between a resistor and the resistance of the gap, suggesting that unforced spray can be adjusted and stabilised externally by using the series resistor method.

Impedance properties of polypyrrolic sensors prepared by MAPLE technology

Thin sensitive layers of polypyrrole (PPY) are deposited onto alumina sensor substrates by matrix-assisted pulsed laser evaporation (MAPLE) technology. The depositions are carried out with the KrF excimer laser from dimethylsulfoxide (DMSO) matrix. After 1-month “ageing” period the complex impedance of prepared sensors is measured in the frequency range from 15 Hz to 10 MHz in following atmospheres: “pure” synthetic air and synthetic air with variable (23% or 90%) relative humidity. The general character of Nyquist diagrams, plots of complex admittance versus frequency, parameters of sensor equivalent circuit and phase-angle sensitivities are then evaluated from the obtained impedance data. While equivalent circuit capacity ( C) of PPY-based sensors remains from 1.7 to 2.0 pF in all the above-mentioned atmospheres, equivalent circuit resistance ( R) varies widely from 6 to 140 MΩ, mostly in dependence on surrounding atmosphere humidity. The differences in charge-transport mechanisms between PPY and tin dioxide sensitive layers and also influence of surrounding atmosphere to electric properties of PPY are discussed.

Quartz resonator signatures under Newtonian liquid loading for initial instrument check

The quartz crystal microbalance (QCM) has been increasingly utilized in the monitoring of the deposition of thin macromolecular films. Studies in the deposition of polymers, biomaterials, and interfacial reactions under electrochemical environment are some of the conditions for the study of these material and deposition properties at a lipid interface. Numerous studies have shown the difficulties in configuring an experimental setup for the QCM such that the recorded data reflect only the behavior of the quartz crystal and its load, and not some artifact. Such artifacts for use in liquids include mounting stress, surface properties such as hydrophobicity, surface roughness coupling to loading liquids, influence of compressional waves, and even problems with the electronic circuitry including the neglect of the quartz capacitance and the hysteretic effects of electronic components. It is thought useful to obtain a simple test by which the user could make a quick initial assessment of the instrument's performance. When a smooth quartz crystal resonator is immersed from air into a Newtonian liquid, the resonance and loss characteristics of the QCM are changed. A minimum of two experimental parameters is needed to characterize these changes. One of the changes is that of the resonant frequency. The second is characterized by either a change in the equivalent circuit resistance (Δ R) or a change in the resonance dissipation (Δ D). Two combinations of these observables, in terms of either Δ f and Δ R or Δ f and Δ D, which we define as Newtonian signatures of S 1 and S 2 , are calculated to have fixed values and to be independent of the harmonic and of the physical values of the Newtonian liquid. We have experimentally determined the values of S 1 and S 2 using three different QCM systems. These are the standard oscillator, the network analyzer, and the QCM dissipation instrument. To test the sensitivity of these signatures to surface roughness, which is potential experimental artifact, we determined the values of S 1 and S 2 for roughened crystals and found that these signatures do reflect that experimental condition. Moreover, these results were qualitatively in accord with the roughness scaling factor described by Martin.

Photoconductive CdS: how does it Affect CdTe/CdS Solar Cell Performance?

AbstractPhotoconductive CdS (PC-CdS) in CdS/CdTe solar cells from five different sources is investigated using spectral sensitization of apparent quantum efficiency (AQE) and J-V analysis. Red bias light significantly enhances the blue AQE, commonly leading to AQE>1 below 550 nm, and blue bias light enhances the red AQE, but to a much smaller extent. These enhancements are more pronounced with increasing forward bias, after stress and in devices with intentionally Cu-doped CdS. This behavior is observed to some degree in all devices with CdS, but is absent in cells without CdS. These effects are consistent with blue light, either ac monochromatic or dc bias, increasing the CdS conductivity. This causes an increase in the field and depletion width in the CdTe to maintain balanced space charge, leading to increased collection of carriers from the CdTe. The CdS conductivity modulation can also change the AQE due to a change in equivalent circuit resistance. Analysis of J-V data measured with white, blue, red or no light indicates little dependence of series resistance or diode quality factor on the illumination spectrum. Thus, the PC-CdS resistance has little effect on the solar cell J-V performance, but does influence AQE.

Fast Fourier transform admittance analysis method applied to thickness-shear-mode acoustic wave sensors

A fast Fourier transform admittance analysis (FFT-AA) method, applied to thickness-shear-mode (TSM) acoustic wave sensors, is first proposed and the corresponding theory is presented. Based on the FFT-AA, an oscillatory waveform with the feature of a damped free oscillation is obtained experimentally. It can illustrate dynamically and directly the vibratory characteristics of TSM sensors, which can be considered as an important advantage over an admittance spectrum obtained by admittance analysis. Compared with the motional resistance in equivalent circuit, the decay time, obtained by Levenberg-Marquardt algorithm through the fit of the oscillatory equation to oscillatory waveform, is more suitable for characterization of the electrical energy dissipated in the quartz crystal. The oscillatory features of TSM sensor are investigated by FFT-AA in different medium. The decay times are 0.1807, 0.0761 and 0.2300 μs with the media being air, water and dry coating film respectively. Finally, the proposed method has been successfully applied to monitor a curing process of coating polymer. It is therefore shown to be a useful technique to study oscillatory behavior of TSM acoustic wave sensors.

Determination of the state-of-charge of a lead-acid battery using impedance of the quartz crystal oscillator

Electrolyte density in a lead-acid battery may vary by up to 20% during the discharge-charge cycle and this property can be used as an indication of the amount of stored energy. We describe the application of impedance measurements on a 10 MHz AT cut quartz crystal immersed in solutions of 0–59 wt% sulphuric acid for the purpose of determining the state-of-charge during battery operation. Changes in impedance magnitude, phase angle and equivalent circuit resistance were followed, all of which showed strong dependency on viscosity and density. Good agreement with the theoretically predicted behaviour of the motional resistance of thickness shear mode oscillators immersed in liquids was observed. These passive measurements of the crystal properties gave reproducible values, in contrast to active measurements involving determination of the frequency of a resonating circuit incorporating the crystal, which we have previously found to suffer from instability. Combining computer data acquisition and processing with appropriate calibration curves enabled direct monitoring of the discharge of a leadacid battery.

The effect of conductivity losses on propagation through the helical slow-wave structure of a traveling-wave tube

A general theory has been developed to account for the material conductivity losses on the performance characteristics of a helical slow-wave structure (SWS) traveling-wave tube (TWT). The effects of helix/envelope conductivity have been studied on various propagation parameters, namely, the axial propagation constant, the interaction impedance, the attenuation constant, and the equivalent circuit resistance per unit length of the structure. While with the first two of these parameters, these effects are found to be only of the second order, they are quite significant for the remaining two. The functional dependence of the propagation parameters on the other structure parameters of importance namely, the relative permittivity of the helix supports, the envelope-to-helix separation, the helix pitch angle, and the thickness of the helix wire, has also been shown. The generalized theory developed here has been further tested by comparing the results with those obtained elsewhere for some special cases. >

Diode Mixer Coefficients for Spurious Response Prediction

The precise prediction of spurious response levels in a superheterodyne receiver would greatly aid the receiver designer besides being necessary for the representation of a radio frequency interference environment. The power series is used to represent the nonlinear receiver mixer in order to obtain an expression for the receiver spurious response sensitivity. This sensitivity expression contains the power series coefficients and shows that the coefficient magnitudes must be known before the spurious response levels can be computed. Therefore, a method is developed to provide a solution for the power series coefficients of a typical mixer circuit configuration. In the analysis to determine the coefficients, the input voltage-output current loop equation is written for a crystal mixer equivalent circuit. This expression is expanded in a power series and then the reversion of a series technique is implemented to obtain the desired output-input expression in series form. The effects of the nonlinear element (diode) and the total circuit resistance are included in the results. Coefficient expressions are determined up to the ninth order in the manner described above and the level of each expression is computed versus the product α( IR + Iß) RT where α and IR are diode parameters, RT is the equivalent circuit resistance, and Iß, is the dc bias current. Also, the effect of diode bias upon spurious response sensitivity is considered and the results are plotted. The results show the mixer dc operating conditions which must exist in order to reduce spurious response sensitivity.

Some Additions to the Theory of Radio-Frequency High-Voltage Supplies

The double-tuned overcoupled air transformer, commonly used in radio-frequency high-voltage supplies, is represented by an equivalent primary circuit. This circuit can be used very advantageously to develop the theory of operation of the oscillator, including the two possible operating frequencies, the necessary conditions for oscillation and maximum efficiency, and the variation of operating frequency and load resistance with primary tuning. It is shown that, at the operating frequency, the load impedance is purely resistive. The various resistances in the circuit representing the power losses and the load resistance are included in the equivalent circuit resistance, which appears as the plate load of the class-C oscillator tube. This greatly facilitates the design of a circuit to give any required power and voltage output. There are several ways in which this design problem can be approached, and the paper outlines the method which was used and found successful by the author.