Peak Value Of Current Research Articles

NUMERICAL SIMULATION OF REPRODUCTION OF THE DEVELOPMENT CONDITIONS OF THE NEXT TRICHEL PULSE IN NEGATIVE CORONA

Numerical simulations of the negative corona at a constant applied voltage in the Trichel pulse mode are carried out for different contents of an electronegative gas component. The dependences of the total current peak value and the time interval between pulses on the values of the applied voltage and the content of electronegative components are obtained. The results are somewhat explained using simplified models.

A sensitive voltammetric and density functional theory calculations analysis for the direct interaction of sulfide ion with the multiwalled carbon nanotube

A sensitive and simple cyclic voltametric method was investigated for the direct electrochemical determination of sulfide using multiwalled carbon nanotube paste electrode (MWCNTPE). The sulfide exhibited a distinct and remarkable direct oxidation peak at about 0.56 V in a solution containing sodium chloride as a suitable supporting electrolyte. The effect of voltametric behavior of sulfide was also studied in various supporting electrolyte. Among this sodium chloride containing solution showed a well-defined oxidation peak current as compared to the other supporting electrolyte. The direct oxidation behavior of sulfide in sodium chloride solution was mainly attributed to the less hindrance effect of the electrolyte anions on the surface of electrode. Under optimized condition the oxidation peak current values were found to increase in a linear way with increasing sulfide concentration in the range from 1 × 10−7 to 3 × 10−5 M (R2 = 0.9985). The detection limit (DL) was calculated to be 4 × 10−8 M for the sulfide concentrations. The developed method showed excellent selectivity towards the voltametric determination of sulfide as compared to other competing ions like Br−, NO3−, F−, PO43−, NO2−, I−, CH3COO− present in the solution. Moreover, the method demonstrated good and reproducible results with relative standard deviation (RSD) of 3.8% after 40 successive measurements. The method was successfully applied for determination of sulfide in local tap water samples without any matrix effect. Meanwhile to support the voltametric behavior of sulfide, density functional theory (DFT) calculations were performed at ωB97XD/6-31G(d,p) level of theory to get deep insight into the electronic properties of MWCNT and adsorbed analytes (sulfide) using Gaussian 09 package. The highest interaction energy and the decrease in energy gap of multiwall carbon nanotube with sulfide (MWCNT-S2-) complex are consistent with the highest sensing behavior of MWCNT towards sulfide ion in experimental results.

Experimental Study on the Initial Current Characteristics of Laser-Triggered Vacuum Switch During Trigger Process

The trigger characteristics of the laser-triggered vacuum switch (LTVS) are significantly affected by the parameters of the laser-produced initial current. In this paper, a low operating voltage is applied across LTVS, and the trigger experiments are carried out under different laser energy and operating voltage. The initial current is obtained by measuring the voltage drop across a 25 Ω resistor. The influence of laser energy and operating voltage on the trigger characteristics can be characterized by the parameters of the initial current, such as the current peak value, the number of charges released, the rate of rise, and the delay time. The experimental results show that an increase in laser energy can increase the current peak value, the number of charges released, and the rate of rise, and can decrease the delay time. These results show that an increase in laser energy helps the LTVS trigger process. The external electric field is much smaller than the laser electric field. Hence, only the current peak value is affected by the operating voltage, and the impact on the other current parameters is weak.

Initial Rotor Position Estimation of SynRM Based on Pulsating Voltage Injection Combined With Finite Position Set Algorithm

Initial rotor position estimation is the basis of stable starting without reverse rotation; also initial position estimation directly affects the maximum starting torque. DC pulse voltage injection is one of the common methods for estimating the initial rotor position, which has low implementation complexity. However, the conventional DC voltage pulse injection methods, which works through injecting three DC voltage pulses, has low accuracy and slow response in estimating initial position. A rotor initial position estimation method based on pulsating voltage injection combined with an iteration algorithm is proposed in this paper. This method works by injecting only one DC voltage pulse to the motor and measuring the peak values of currents and fluxes of the motor; afterwards these values should be applied to an iterative algorithm. The iteration algorithm in the proposed method leads to increment of the accuracy of initial position estimation, and reduction of the number of injected dc pulses in comparison with the conventional methods. The performance of the proposed method is verified experimentally on a synchronous reluctance motor (SynRM). Also, a comparison between the two conventional methods and the proposed method is provided by this SynRM drive experimental setup.

Nano‐Nickel Doped Carbon Xerogel: Synthesis, Characterization and Catalytic Performance towards Ethanol Fuel Electro‐oxidation

AbstractIn this work, the synergism between the nano nickel particles and its carbon xerogel support, CX, together with their graphite substrate, G, leads to an efficient Nickel/CX/G electrode for electrocatalysis of ethanol oxidation reaction, EOR. The preparation conditions are optimized. The optimum electrode is made of 6 % weight of Ni doped in CX matrix and drop‐casted on a graphite surface, Ni‐6/CX/G. The catalyst structure and morphology are investigated using XRD, SEM, TEM and FTIR techniques. The electrochemical activity towards EOR is tested in 1 M NaOH+1 M Ethanol solutions by cyclic voltammetry combined with a rotating ring disk electrode. The optimum electrode shows an oxidation peak current density value of 5925 and considerable stability. This electrode may serve as a good candidate for the anode in the Direct Alkaline Ethanol Fuel Cell, DAEFC.

Fast Current Control Based on Indirect Current Sensing of The Full-Bridge Converter Associated with An Electromagnetic Micro-Actuator

This paper deals with the fast current control of the full-bridge converter loaded with a digital electromagnetic micro-actuator. Input current sensing method is proposed for the initial full-wave control of output current. Input current analysis takes parasitic parameters into account and shows that input current approximately equals output current during the full-wave state. The peak value of input current during steady state is twice the output current. A multi-scale closed-loop control is then implemented, which ensures stable fast current control. In the micro-actuator application, converters are tightly integrated with micro-actuator at output side. Input shunt sensor is easier to implement and has lower power dissipation compared with output shunt sensor. This solution has been validated with an experimental test bench. FPGA board is used to implement the proposed control strategy. Experimental results show that the start-up duration is greatly reduced, thereby realizing the fast current response.

Bioelectricity generation through Microbial Fuel Cells using Serratia fonticola bacteria and Rhodotorula glutinis yeast

Nowadays, there is great interest in microbial fuel cells because of the different substrates that can be used in them for electric energy generation. In order to find an alternative and contribute with eco-friendly technologies, this research used the Serratia fonticola bacteria and Rhotula glutinis yeast as a fuel source through laboratory scale microbial fuel cells. A single chamber microbial fuel cell with air cathode was fabricated with a copper foil and a graphite plate as anode and cathode electrode respectively. For the characterization of the cells, physicochemical parameters such as voltage, electric current, pH and electrical conductivity were measured for 30 days and at room temperature (18 ± 2.2 °C). It was possible to generate peak voltage and current values of 0.53 ± 0.01 V and 0.55 ± 0.02 V and current values of 1.76 ± 0.16 mA and 1.52 ± 0.02 mA, for MFCs with bacteria and yeast respectively. In addition, acidic operating pH was observed, and its conductivity peak values around 242 mS/cm. Finally, this work demonstrates the great potential that microorganisms have for the generation of electric current, giving a new and promising way to generate electricity

Optimizing Sustainable Energy Generation in Ethanol Fuel Cells: An Exploration of Carrageenan with TiO2 Nanoparticles and Ni/CeO2 Composites.

Based on the search for new biodegradable materials that are low cost and easy to synthesize by environmentally friendly methods, we report the use of carrageenan membranes (mixture of κ and λ carrageenans) with different concentrations of titanium dioxide nanoparticles (TiO2 NPs) and Ni/CeO2 (10 wt % Ni) for the fabrication of a novel fuel cell electrode for the oxidation of ethanol. Each membrane was characterized to determine its physicochemical properties using X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. Using impedance spectroscopy (IS), a maximum value of 2.08 × 10-4 S/cm in ionic conductivity was found for the carrageenan nanocomposite with a concentration of 5 wt % TiO2 NPs (CR5%). Due to its high conductivity values, the CR5% membrane was mixed with Ni/CeO2 to prepare the working electrode for cyclic voltammetry measurements. Using a solution of 1 M ethanol and 1 M KOH, the oxidation of ethanol over CR5% + Ni/CeO2 resulted in peak current density values at forward and reverse scan voltages of 9.52 and 12.22 mA/cm2, respectively. From our results, the CR5% + Ni/CeO2 membrane proves to be more efficient in the oxidation of ethanol compared with commercially available Nafion membranes containing Ni/CeO2.

Study on discharge characteristics of pulsed power module under the condition of discharge short circuit fault

Efficiency and safety are key factors that must be emphasized in pulsed power applications. The discharge characteristics of pulsed power supply directly determine the performance of the railgun. This paper conducts a research on short-circuit faults in transmission coaxial cables of pulsed power supply. In order to study the effect of short-circuit fault on the discharge characteristics of pulsed power supply and system efficiency,a pulse-forming network with cable short-circuit failure and dynamic railgun model are established in the paper. The effect of short-circuit fault on peak current is discussed by simulation. The results show that the short-circuit fault currents are all higher than the currents under normal conditions, and the closer the short-circuit location is to the power supply side, the higher the peak value of current is. In some extreme case, the peak fault current exceeds 1.5 times the normal, which requires consideration of short-circuit fault protection measures, such as the addition of a DC circuit breakers.

Metal-free DNA sensor based on 10-phenylphenothiazine photo-ATRP signal amplification

The development of ultrasensitive deoxyribonucleic acid (DNA) sensors related to the disease is of great significance for early diagnosis and prevention of the disease. Here, an ultrasensitive DNA sensor based on the photocatalytic atom transfer radical polymerization (photo-ATRP) strategy was prepared. In this strategy, the target DNA was specifically recognized by sulfhydryl-modified peptide nucleic acid (PNA), and α-bromophenylacetic acid (BPAA) was grafted onto the DNA via phosphate-Zr(IV)-carboxylate. In the presence of photocatalyst 10-phenylphenothiazine (PTH), α-Br was reduced under 365 nm UV light to generate active radicals, and the polymer chain containing electrochemical signaling molecule (ferrocene) was introduced to the electrode surface by mediated ATRP. Finally, the peak current value was measured by square wave voltammetry (SWV) and the concentration of DNA was evaluated. The biosensor was constructed based on a green strategy for ATRP reaction without using a heavy metal catalyst (metal-free), thus reducing the pollution of the environment. Moreover, under optimal conditions, the relationship between the DNA sensor and the target was linear in the concentration range of 0.1 fM ∼ 10 pM, and the limit of detection was 79 aM. The sensor has the advantages of high sensitivity, interference-free and good stability, which indicates that it has great practical application potential in the field of life science and medical research.

Wireless Battery Chargers Operating at Multiple Switching Frequencies with Improved Performance

The operation of wireless battery chargers at multiple switching frequencies may lead to a noticeable suppression of conducted and radiated electromagnetic interference (EMI) at the cost of decreased efficiency (mainly at lower load resistances) and increased peak and root mean square values of currents of power components of the wireless battery charger. Moreover, the reduction in conducted EMI is only moderate (<8.3 dB). Therefore, a novel approach based on modified resonant circuits and a modified control technique to obtain better reduction in the conducted and radiated EMI without significantly compromising other performance characteristics of the wireless battery charger is proposed and validated by using simulations and experiments. It is shown in this paper that the wireless charger operating at multiple switching frequencies with the proposed approach for the performance improvement has a more effective implementation of the four-switching frequency spread-spectrum technique with better conducted and radiated EMI reduction at all load resistances, lower values of peak and RMS currents at all load resistances, and higher efficiency in constant current mode and in the beginning of constant voltage mode (at lower values of the load resistances) than that of the conventional wireless charger operating at multiple switching frequencies.

Novel deliberately sensitive and selective penciclovir voltammetric sensors depending on iron oxide nanoparticles carbon paste electrodes

The present study described the construction and electroanalytical characterization of a novel penciclovir (PCV) voltammetric carbon paste sensor fortified with iron oxide nanoparticles (FeONPs/CPEs). Integration of the electrode matrix with iron oxide nanoparticles obviously enhanced the PCV oxidation peak based on its electrocatalytic activity towards the electrooxidation of PCV molecule at the electrode surface. At the optimized pH value, PCV exhibited an irreversible oxidation peak at about 1.03 V following a diffusion–reaction mechanism. Differential pulse voltammograms (DPVs) registered peak current values correlated linearly to the corresponding PCV within the concentration range from 0.09 to 4.656 µg mL−1 PCV with LOD value 0.025 µg mL−1. Based on the electrochemical behavior of PCV at various pH and the scan rate values, and with the aid of molecular orbital calculations, the electrooxidation reaction of PCV molecule undergoes through oxidation of the terminal amino group of the guanine moiety with the participation of one electron and two protons. Based on the reported selectivity and sensitivity of the FeONPs/CPE, PCV can be assayed in pharmaceutical formulations, biological fluids and surface water samples with average recoveries agreeable with the official HPLC-UV method.

The influence of ultrasonic processing on the structure and electrophysical properties of fruit in combined drying

The intensification of ultrasonic vibrations for the processing of agricultural products is becoming increasingly important in the food industry, as it can reduce energy consumption for the dehydration of raw materials. The research aims to study the effect of sonication on the change of electrophysical parameters and structure of apple raw materials in the process of combined drying using direct electric heating. Using scanning electron microscopy, images of the surface structure of dried apple samples were obtained at different combinations of sonication duration and methods of heat supply to the raw material during the drying process. Based on the experimental studies, the dependences of the current flowing through the sample in the process of combined drying using direct electric heating on the duration of raw material processing in an ultrasonic bath were obtained. The influence of preliminary sonication on the maximum values of the current strength during direct electric heating was determined. The dependences of changes in the resistivity of apple samples during dehydration at different pretreatment durations were investigated. The effect of ultrasound on the initial resistivity of apples, the duration of electro-plasmolysis, and the resistivity values at which the maximum values of the direct electric heating current are observed were determined. The results of the experiments show that the pretreatment of raw materials in an ultrasonic bath can reduce the peak current values by up to 27%. The initial values of the resistivity of the raw material after sonication are reduced by 7.8-13.8% compared to the control samples. The obtained images of the dried fruit surfaces showed an increase in the porosity and roughness of the samples. The obtained results of experimental studies can become a prerequisite for the development of an energy-efficient technical means of ultrasonic processing of fruit and vegetable raw materials before drying and the selection of optimal operating modes

Transformer-Less Soft-Switching High-Gain PWM Boost Converter With Reduced Components and Increased Effective Duty Cycle

A transformer-less soft-switching high-gain pulsewidth-modulation (PWM) converter is proposed in this article. The proposed converter is derived from a single-switch dual-inductor transformer-less boost converter by replacing the complementary diode connected to the switch with a synchronous rectifier switch. Moreover, the peak value of the reverse current of the rear-end inductor in continuous bidirectional conduction mode (CBCM) is regulated to exceed the input inductor valley current. Based on these two measures, the zero-voltage switching (ZVS) for all switches and the natural turn-off for the output diode are realized, and the effective duty cycle is enhanced. Besides, the proposed ZVS converter has the merits of fewer power components count, reduced voltage stress, and lower cost. Furthermore, the ringing issue in the original topology under light load or high input voltage conditions is eliminated. The operation principle, steady-state characteristics, dynamic model, soft-switching operation, and realization conditions are analyzed in detail, and subsequently, the parameter design method is elaborated. The proposed topology demonstrates an enhanced efficiency performance over wide operating operations with a maximum efficiency of 97.1%.

Mathematical characterization of performance and durability for the WO3 – Nb2O5 electrochromic thin films using finite experimental data

A comparison is made among the peak current density values of 1000 cycles of experimental chronoamperometry for WO3-Nb2O5 films with the simulated values. Quadratic and linear regression models are developed by using MATLAB standard function ‘fitlm’ to get least MSE and ‘predict’ method to extrapolate the current density values. Initial 400, 500, and 600 experimental cycles are used as starting references for predictions. Predicted model having −0.09 percent change with the experimental curve is followed to predict 10,000 cyclic values with −4.73 % difference. Binding energy values for W6+ (35.9, 38.05 eV), W5+ (36.8, 34.65 eV) and Nb5+ (210.35, 207.55 eV) are measured.

Electrochemical detection of boric acid using gallacetophenonato-(β-diketonato) ruthenium complex in water.

A simple and practical method for boron detection in water is desired in various fields such as seawater desalination, water conservation, and plant production. To develop a method for detecting boron as boric acid in water, we synthesized [Ru(acac)2(H2thap)] (acac = acetylacetonat ion, thap = 2',3',4'-trihydroxyacetophenonate (gallacetophenonate) ion) possessing a cis-diol moiety that interacts with boric acid. A comparison of UV-visible (UV-vis) absorption spectra measured in the presence and absence of boric acid at various pH values revealed that [Ru(acac)2(H2thap)] shows the highest response to boric acid at pH 8.5. Cyclic voltammograms (CVs) and differential pulse voltammograms (DPVs) of [Ru(acac)2(H2thap)] aqueous solution at pH 8.5 with varying boric acid concentrations showed a decrease in the peak current value at 0.032V (vs. Ag|AgClaq.) and an increase in the peak current value at 0.444V with increasing boric acid concentration. On the basis of the relationship between the ratio of current values (at 0.032V and 0.444V) and boric acid concentrations, the binding constant (assuming a 1:1 binding model) for the interaction between [Ru(acac)2(H2thap)] and boric acid was estimated to be 135.1 ± 9.1mol-1 dm3, and the Limit of Detection (LOD) was calculated to be 1.03mg B L-1.

A graphene-assisted electrochemical sensor for detection of alpha-fetoprotein in serum

Alpha fetoprotein (AFP) is a specific tumor marker for the diagnosis of primary liver cancer. In this work, a molecularly imprinted (MIP) electrochemical sensor for AFP was prepared by surface imprinting method. The MIP electrochemical biosensor uses polysulfide cordial and graphene-gold composite as electrode modified nanomaterials to effectively enhance the detection of electrical signals. Dopamine (DA) is the functional monomer and the PDA-AFP complex is obtained by electropolymerization. The eluent elutes the functional monomer and the specific cavity formed can adsorb the target molecule. Under optimal experimental conditions, differential pulse voltammetry (DPV) was used for detection. The current of the prepared biosensor decreases with increasing AFP concentration. The peak current value of DPV assay showed good linearity with the logarithm of AFP concentration in the range of 0.01 ng/mL-1000 ng/mL. The detection limit can reach 3.7 pg/mL.

Fixed Switching Frequency Hybrid Modulation With ZVS for Single-Phase Inverter

Soft switching technology is an effective way to reduce the switching loss of the single-phase inverter to improve efficiency. Because of the ease of implementing soft switching, inverter works in boundary conduction mode (BCM) is widely used. On the contrary, BCM causes wide variation in switching frequency and large inductor current ripple. In this article, a fixed switching frequency hybrid modulation method for the inverter is proposed, which can achieve zero-voltage switching without changing the switching frequency and reduce the peak value of inductor current. The modulation achieves good tracking of the output current with different loads by switching mode between the triangular mode and the trapezoidal mode accurately. For implementing modulation, the operation states of the inverter with different conditions are analyzed in detail, the number of operation states is deduced and the state machine about mode switching is summarized. In addition, a single-phase inverter prototype is designed to verify the feasibility and effectiveness of the proposed modulation. Compared with BCM, the efficiency of the inverter at both light load and full load is increased.

Study on the Heterogeneous Nucleation Mechanism of SiCp/AZ91 Magnesium Matrix Composites under Pulse Current

SiCp/AZ91D magnesium matrix composites with 30% SiCp were successfully prepared by pulsed current melting in this work. Then, the influences of the pulse current on the microstructure, phase composition, and heterogeneous nucleation of the experimental materials were analyzed in detail. The results show that the grain size of both the solidification matrix structure and SiC reinforcement are refined by pulse current treatment, and the refining effect is gradually more obvious with an increase in the pulse current peak value. Moreover, the pulse current reduces the chemical potential of the reaction between SiCp and Mg matrix, thus promoting the reaction between SiCp and the alloy melt and stimulating the formation of Al4C3 along the grain boundaries. Furthermore, Al4C3 and MgO, as heterogeneous nucleation substrates, can induce heterogeneous nucleation and refine the solidification matrix structure. Finally, when increasing the peak value of the pulse current, the repulsive force between the particles increases while the agglomeration phenomenon is suppressed, which results in the dispersed distribution of SiC reinforcements.

Characteristics of Resonant Tunneling in Nanostructures with Spacer Layers

The effect of spacer layers on electron transport through two-barrier nanostructures was studied using the numerical solution of the time-dependent Schrodinger–Poisson equations with exact discrete open boundary conditions. The formulation of the problem took into account both the active region consisting of a quantum well and barriers, as well as the presence of highly doped contact layers and spacer layers. The use of the time formulation of the problem avoids the divergence of the numerical solution, which is usually observed when solving a stationary system of the Schrodinger–Poisson equations at small sizes of spacer layers. It is shown that an increase in the thickness of the emitter spacer leads to a decrease in the peak current through the resonant tunneling nanostructures. This is due to the charge accumulation effects, which, in particular, lead to a change in the potential in an additional quantum well formed in the emitter spacer region when a constant electric field is applied. The valley current also decreases as the thickness of the emitter spacer increases. The peak current and valley current are weakly dependent on the thickness of the collector spacer. The collector spacer thickness has a strong effect on the applied peak and valley voltages. The above features are valid for all three different resonant tunneling nanostructures considered in this study. For the RTD structures based on Al0.3Ga0.7As/GaAs, the optimized peak current value Ipmax = 5.6 × 109 A/m2 and the corresponding applied voltage Vp = 0.44 V. For the RTD structures based on AlAs/In0.8Ga0.2As, Ipmax = 14.5 × 109 A/m2 (Vp = 0.54 V); for RTD structures based on AlAs/In0.53Ga0.47As, Ipmax = 45.5 × 109 A/m2 (Vp = 1.75 V).