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This paper proposes a new optimization method and its platform for automatically adjusting the control parameters of a digital active gate driver using a PWM inverter. The proposed optimization method applies the searching parameters for only any duration in an ac current cycle and fixed parameters for the other duration. This enables us to find the optimal operating points of power devices so as to reduce the surge voltage and switching loss with the consideration of their dependency on the load current. Additionally, the proposed optimization method also can find the operating points while the inverter performs a continuous switching operation. For this reason, the proposed optimization method can be applied to a continuous running test of PWM inverters, for example, in a manufacturing process. The validity of the proposed method and platform was evaluated by using a 10-kW three-phase PWM inverter with digital gate drives. The experimental results confirmed that the proposed optimization method makes it possible to find the optimal operating points for reducing the surge voltage and/or the power loss.

Superconducting coils may suffer from electromagnetic vibration due to changing electromagnetic fields under AC conditions. In the long term, this vibration may cause performance degradation of superconducting tapes. In order to study the influence of electromagnetic vibration between superconducting tapes on their performance, the study can be started from the simplest form of electromagnetic vibration, that is, the electromagnetic vibration between two superconducting tapes. The degree of electromagnetic vibration under different AC currents were analyzed by simulation, and the variation of critical current ( I c) and the n-value of Y-Ba-Cu-O (YBCO) tapes after undergoing long-term electromagnetic vibration through experiments were measured. The results show that two YBCO tapes does not show obvious performance degradation under tens of hours the electromagnetic vibration caused by the AC current amplitude of 1.2 to 1.4 times Ic .

The aim of this work is to optimize EPD variables (voltage, time, and focus) using alternating current through the Taguchi Design of Experiment (DOE). Coating Nano hydroxyapatite (Nano-HA) on a Ti6Al4V substrate depends on thickness and roughness, then characterization of a coating layer to determine the optimum state. Hydroxyapatite (HAp) powder was deposited on a Ti-6Al-4V alloy substrate by electro-deposition with ethanol as a solvent under AC current, to improve the alloy surface quality based on coating thickness and maximum coating mass meeting the requirements of a biological orthopedics application. Ethanol was used as a solvent to precipitate ketazone and HAp on the base alloy. Taguchi's approach was used in order to determine the optimal conditions for EPD and subsequently to apply various criteria for depositing the biochemical coating. The surface and cross-section composition of the paint is described by characterization. Numerous tests and inspections; Zeta, XRD and SEM stability test, water contact angle and optical microscopes were used to describe the surface morphology of the HAp layer. The value of the optimum conditions for deposition of the HAp layer which is a simultaneous thickness and maximum coating mass, was predicted at a sedimentation voltage of 40 V, 2 min sedimentation time and 1 g / L for the concentration of the suspended solution at room temperature. The validity of the model resulting from the response surface methodology was assessed by comparing the expected results with the experimental results. In addition, close agreement was observed between the experimental results and the expected results. For the solution at room temperature, the results obtained with the highest value of the coating thickness of 41at the surface roughness of 0.94 and the contact angle of the alloy before coating is 67.489º reduced to. 38.132º after plating, which indicates an increase in the harmony of the metal implant and biocompatibility.

Currently, the world's energi needs are still dominated by depleting fossil fuels, where the largest consumption produced from these fossils is electrical energi. For tropical country conditions, on average, every house and in city buildings use split AC as a tool to condition the room so that it feels comfortable for its residents. Where about 60% utilize electrical energi. In this study, split AC uses solar power as an alternative to electrical energi by using a solar photovoltage (PV) system as a medium for absorbing solar radiation to be converted into electrical energi in split AC. The goal is that the use of solar radiation is able to reduce the use of electricity from PLN, which so far requires a large amount of money. The research method begins by making a model of a device that is modified by an electric panel on a split AC connected to an inverter to convert DC to AC current from the PV cell. From the use of solar cells as electrical energi then the test results are compared with conventional split AC. The results obtained from the conventional split AC test can be seen that the efficiency is 85% while the solar-powered split AC has an efficiency of 73%, but for the use of electrical power that operates for 2 hours on a solar-powered split AC, it is more efficient with a power of 376 Wh per day.

Article is dedicated to organization and conduct of the calibration results of reciprocal interlaboratory comparisons for the multifunctional calibrator of electric quantities: DC voltage, AC voltage, DC current and AC current. The interlaboratory comparisons of electric quantities measurement instruments calibration results are represented. Evaluation of the laboratory calibration results bias is provided using the modified criterion. Analysis and conclusions concerning participating laboratory competence are provided.

Litz wire has been widely utilized in power transformers and inductors as a wire with low copper loss at high-frequency operation. The Litz wire is commonly made of many thin isolated strands twisted in multiple levels. Due to its complicated structure, the copper loss prediction of the Litz wire has been difficult, hindering the design optimization of the Litz wire structure. To overcome this difficulty, preceding studies have investigated the analytical copper loss models of the constituting elements of the Litz wire, i.e., the strands and the bundles of strands. The purpose of this article is to propose an analytical copper loss model of the Litz wire by utilizing these preceding knowledge. The proposed model is formulated only with parameters that can be measured by basic testing instruments. Besides, the proposed model considers the bundle structure of the Litz wire, which affects the local ac current distribution, and the twisting pitch, which causes the inclination of the Litz wire strands. The proposed model was tested by comparing the analytical prediction and experimental measurements of the ac resistance of commercially available Litz wires. As a result, the predicted ac resistance showed good agreement with the measured ac resistance, suggesting the appropriateness of the proposed model.

The Electro-Magnetic (EM) MEMS switches are playing an important role in our everyday life due to their high efficiency and system integrity. The design, modelling and testing of MEMS EM switch is presented in this research work. This chip-based MEMS switch is fabricated using 0.35 µm Complementary Metal Oxide Semiconductor (CMOS) three metals-two poly technology, released i.e., post micromachining and packaged in Dual Inline package (DIP). The electromagnetic actuation-based CMOS-MEMS switch consists of two central coils joined to each other and two supporting beams. The two coils actuate in torsional mode by passing DC as well as AC current through coils. Switch is tested in static and dynamic modes. Actuation voltages of 68 V are measured in the static mode, while in dynamic mode, voltages are 68 mV. Finally, compared theoretical and experimental measurements.

In this study, the magnetoimpedance (MI) and stress impedance (SI) effect properties of Fe77.5Si7.5B15 wires have been investigated. Wires were annealed at 460 oC for different times. The largest change in the MI was observed at 1MHz ac current frequency value. At this frequency value, the change in MI was about 40% in the wire that as-received, while the change in the wire heat treated at 460 oC for 10 minutes was found to be 169%. It has been determined that low time annealed leads to increase in magnetic softness., Bu çalışmada Fe77.5Si7.5B15 tellerin manyetoempedans (MI) ve stresempedans (SI) etki özellikleri incelenmiştir. Teller 460C de farklı sürelerde ısıtılmıştır. MI değerinde en büyük değişim 1MHz ac akım frekans değerinde gözlenmiştir. Bu frekans değerinde, ısıl işlem görmemiş telde MI değişimi yaklaşık %40 iken 460 C de 10 dakika ısıl işlem görmüş teldeki değişim %169 olarak bulunmuştur. Tellere uygulanan düşük süreli ısıl işlemlerin manyetik yumuşaklıkta artışa yol açtığı belirlenmiştir.

Electrokinetic-assisted phytoextraction (EKPH) involves the use of electric current to improve the mobilization of metals in soils and, therefore, their removal efficiency. It emerges as an interesting sustainable technology for the rehabilitation of abandoned mining areas. The goal of this research was to conduct a comprehensive study of this technique applied to real mine tailings from an abandoned Pb/Zn mine by using ryegrass as plant species and two types of electric current: direct with polarity reversal (DC-PR) and alternate (AC). The EKPH tests were conducted in specially designed plastic containers that allowed recording the main parameters of the electrokinetic process and sampling the different matrices studied, i.e. water, soil and plants. This intensive sampling program allowed detailed monitoring of the metal mobilization processes for the different treatments applied. The changes caused in metal mobility and physicochemical parameters of the tailings due to the application of electric current were reflected to a greater extent in the water samples than in solid ones. Accumulation of Pb, Zn, Cd and Cu in ryegrass tissues increased significantly by 41%, 17%, 34% and 32% when applying 1 V cm−1 of AC current, with respect to the results of phytoextraction without electric current. The application of DC-PR current did not lead, in general, to statistically significant increases in the plant metal uptake. These findings were adequately correlated with the changes found in the metal concentrations of soil pore water and, to a lesser extent, with those observed from the BCR sequential extraction applied to tailings samples., La fitoextracción electrocinética asistida (EKPH) implica el uso de corriente eléctrica para mejorar la movilización de metales en suelos y, por tanto, su eficiencia de eliminación. Surge como una interesante tecnología sostenible para la rehabilitación de zonas mineras abandonadas. El objetivo de esta investigación fue realizar un estudio exhaustivo de esta técnica aplicada a estériles mineros reales procedentes de una mina abandonada de Pb/Zn utilizando ryegrass como especie vegetal y dos tipos de corriente eléctrica: continua con inversión de polaridad (DC-PR) y alterna (AC). Los ensayos EKPH se realizaron en recipientes de plástico especialmente diseñados que permitieron registrar los principales parámetros del proceso electrocinético y muestrear las distintas matrices estudiadas, es decir, el agua, el suelo y las plantas. Este programa intensivo de muestreo permitió un seguimiento detallado de los procesos de movilización de metales para los diferentes tratamientos aplicados. Los cambios provocados en la movilidad de los metales y en los parámetros fisicoquímicos de los estériles debido a la aplicación de corriente eléctrica se reflejaron en mayor medida en las muestras de agua que en las sólidas. La acumulación de Pb, Zn, Cd y Cu en los tejidos de ryegrass aumentó significativamente en un 41%, 17%, 34% y 32% al aplicar 1 V cm-1 de corriente AC, respecto a los resultados de la fitoextracción sin corriente eléctrica. La aplicación de corriente DC-PR no condujo, en general, a incrementos estadísticamente significativos en la captación de metales por la planta. Estos resultados se correlacionaron adecuadamente con los cambios encontrados en las concentraciones metálicas del agua de poro del suelo y, en menor medida, con los observados a partir de la extracción secuencial BCR aplicada a muestras de estériles.

espanolEl Instituto Nacional de Metrologia de Colombia (INM) cuenta con calibradores de alta exactitud (como los Fluke 5720A/5730A) como patrones de referencia de intensidad de corriente alterna (AC). En este articulo describimos la implementacion en el INM de un patron de transferencia de corriente AC-DC basado en convertidores termicos de union simple (SJTC) para mejorar la exactitud de las mediciones de AC y dar trazabilidad al Sistema Internacional de Unidades (SI) dentro del pais. Realizamos una descripcion del modelo de medicion, presentacion del presupuesto de incertidumbre de acuerdo con la Guia para la Expresion de la Incertidumbre de Medida (GUM) y un analisis de los efectos termicos y electrostaticos en las mediciones. Se obtuvieron incertidumbres entre 68 μA/A y 2.6 mA/A para la calibracion de calibradores de alta exactitud y amplificadores de transconductancia, para intensidades de corriente desde 5 mA hasta 20 A (40 Hz a 5 kHz). Los resultados de medicion obtenidos son compatibles con los resultados de calibracion de Institutos Nacionales de Metrologia como el Centro Nacional de Metrologia de Mexico (CENAM) y de Laboratorios Internacionales Acreditados como Flu EnglishThe National Metrology Institute of Colombia (INM) uses high accuracy calibrators (such as Fluke 5720A/5730A) as AC current reference standards. We describe the implementation at INM of AC-DC current transfer standards by single junction thermal converters (SJTC) to improve the accuracy of AC measurements and give traceability to the International System of Units (SI) within the country. We describe the measurement model, present the uncertainty budget estimation accordingly to the Guide to the Expression of Uncertainty in Measurement (GUM) and analyze the effect of temperature and electrostatic on measurements. Expanded uncertainties between 68 μA/A and 2.6 mA/A were obtained for the calibration of high accuracy calibrators and transconductance amplifiers for currents from 5 mA to 20 A (40 Hz to 5 kHz). The obtained measurement results are compatible with calibration results from the National Metrology Institutes like Centro Nacional de Metrologia from Mexico (CENAM) and Accredited International Laboratories like Fluke

This Good Practice Guide is intended for both National and Industrial Metrology Laboratories who wish to invest in the development of a quantum standard for alternating voltage based on the Josephson effect. Dynamic electrical measurements are critical in many applications where the RMS (root mean square) value of an electrical signal does not provide the required information and the signal needs to be sampled and processed. At present, NMIs and calibration laboratories provide traceability with high accuracy using thermal converters, but this is limited to AC magnitudes deduced from RMS values. Therefore, the most accurate commercial calibration equipment is also limited to RMS values. Several research projects have developed AC quantum standards to provide traceability for dynamic measurements within some European NMIs. It is now necessary to establish the traceability chain for dynamic electrical measurements to a wider group of NMIs and calibration laboratories. The text in the Guide is supported by a comprehensive list of references to material already published in scientific literature., Deliverable D8 of project 17RPT03 DIG-AC A digital traceability chain for AC voltage and current

Backpacks are often used by school children as a container or a place to carry their school materials and equipment, so these types of backpacks are very popular with school children. The large number of students wearing backpacks to school can be proven from the results of a survey conducted at SD N Bumisari, Natar District, South Lampung. Of the total number of subjects, 456 elementary school students carried 404 students (88.6%), and 52 students (11.4%) carried sling bags. But they rarely pay attention to the weight of the burden on the bag he carries everyday which turns out to cause injury to back pain.The tool is made in the form of a wearable device where the tool is in the form of a backpack that can be carried anywhere without having to require AC current as input voltage to the tool, because the power uses DC current with a voltage of 5V, the device is made using a microcontroller supported by a 10 kg loadcell sensor, modules HX711, keypad, plus an indicator component in the form of a buzzer. If the bag load exceeds the safe limit, the buzzer indicator will sound.

Spontaneous fluctuations in electrodermal responses are known as nonspecific electrodermal responses (NS.EDRs). The use of NS.EDRs as a tool in applied psychophysiological research has resulted in a variety of publications. NS.EDRs are examined separately as associated with the (as a biomarker of) levels of anxiety. The aim of this study was to compare changes (in terms of amplitude, frequency and time components) in NS.EDRs at two different (pre and post of an external stimulus) resting phases. NS.EDRs (nonspecific skin conductance responses (NS.SCRs), nonspecific skin potential responses (NS.SPRs), and nonspecific skin susceptance responses (NS.SSRs)) were recorded from 50 apparently healthy volunteers simultaneously at the same skin area. They were scored as NS.SCRs and NS.SSRs for changes greater than 0.02 μS and NS.SPRs greater than 0.02 mV. It was found that NS.EDRs, in particular NS.SCRs and NS.SPRs, were significantly changed in the second resting period, following the specific stimulus. More specifically, the amplitude of NS.EDRs were significantly decreased for NS.SCRs (p

[EN] The computer numerical control (CNC) machine has recently taken a fundamental role in the manufacturing industry, which is primordial for the economic development of many countries. Current high quality production standards, along with the requirement for maximum economic benefits demand the use of tool condition monitoring (TCM) systems able to monitor and diagnose cutting tool wearing. Current TCM methodologies mainly rely on vibration signals, cutting force signals, acoustic emission (AE) signals, which have the common drawback of requiring the in-stallation of sensors near the working area, a factor that limits their application under practical terms. Moreover, as machining processes require the optimal tuning of cutting parameters, novel methodologies must be able to perform the diagnosis under a variation of cutting parameters. This paper proposes a novel non-invasive method capable to automatically diagnose cutting tool wearing in CNC machines under the variation of cutting speed, and feed rate cutting parameters. The proposal relies on the sensor information fusion of spindle-motor stray flux and current signals by means of statistical and non-statistical time-domain parameters, which are then reduced by means of a linear discriminant analysis (LDA), and then a feed-forward neural network is used to automatically classify the level of wear on the cutting tool. The proposal is validated with a Fanuc Oi mate Computer Numeric Control (CNC) turning machine for three different cutting tool wearing levels and different cutting speed, and feed rate values., This work was supported by the Spanish 'Ministerio de Ciencia Innovacion y Universidades' and FEDER program in the framework of the 'Proyectos de I + D de Generacion de Conocimiento del Programa Estatal de Generacion de Conocimiento y Fortalecimiento Cientifico y Tecnologico del Sistema de I + D + i, Subprograma Estatal de Generacion de Conocimiento' (ref: PGC2018-095747-B-I00).

The interference law and calculation model of AC transmission lines and other AC facilities on buried long distance pipeline are briefly described. The main influence law of AC current on the passivation behavior of pipeline steel materials is summarized. The research progress on the mechanism and evaluation criteria of AC corrosion of pipeline under cathodic protection is systematically described. The main viewpoints and influencing factors of the mechanism model of ac interference corrosion are summarized, and the main problems of ac interference technology are summarized

To achieve high efficiency rectification, one option is to use synchronous rectification instead of diode rectification. However, synchronous rectification requires an expensive AC current sensor. This is one of the barriers when introducing synchronous rectification. Here we introduce a new synchronous rectification method that does not need any expensive AC current sensors. This new method just uses an DC current sensor, which is cheaper than AC current sensor. The principle of the method is explained in the first part, and the effect of the method is verified by experiments.

The frequency and temperature dependences of the ac electrical conductivity of the MnGaInSe4 single crystals have been investigated. It has been established that, in the temperature range of 295.5–360 K at frequencies of 2 × 104–106 Hz, the electrical conductivity obeys the regularity σ ~ fS(0.1 ≤ S ≤ 1.0). It is shown that the frequency dependence of the electrical conductivity for the MnGaInSe4 single crystal can be explained using a multiplet model and the conductivity in these single crystals is implemented via the band-hopping mechanism. The activation energies have been determined on the basis of dependences logσ ~ 103/T.

AC current regulators are susceptible to controller windup, i.e., the condition in which the controller dynamic states ramp the controller output up to very large values when the commanded reference cannot be achieved because of inverter saturation. Recovering from saturation can take considerable time once the linear mode has been restored, which degrades the current regulator's transient performance and can also impact on its stability. This paper proposes an improved formulation using the concept of signal conditioning, where windup is avoided by feeding the controller states entirely from the constrained inverter pulsewidth modulation command. Unlike previous approaches, this technique has the benefit of a simplified realization, since the controller transfer functions do not require algebraic reformulation. This makes it particularly suitable for multiple cascaded resonators used in harmonic compensation systems. The technique has been validated using simulation and experimental investigations for a grid-connected inverter.

Operation in the high-frequency (HF) regime (3-30 MHz) has potential for miniaturizing power electronics, but designing small efficient inductors at HF can be challenging. At these frequencies, losses due to skin and proximity effects are difficult to reduce, and gaps needed to keep B fields low in the core add fringing field loss. We propose a low-loss inductor structure with step-by-step design guidelines for HF applications. The structure achieves low loss through double-sided conduction in its single-layer winding and through quasi-distributed gaps. An example ~15 μH inductor designed using the proposed design guidelines achieved an experimental quality factor of 720 at 3 MHz and 2A (peak) of ac current. The inductor also improved a high-current-swing power converter operated at 1-3 MHz; at 250 W, the inductor reduced converter losses by 19%, compared to a conventional inductor design. In some cases, litz wire may further improve the performance of the proposed structure. With litz wire, the example inductor had an improved quality factor of 980. Thus, the proposed inductor geometry and design guidelines are suitable for small highly efficient inductors at HF and can thereby help realize high-frequency miniaturization of power electronics. (This paper is accompanied by an example Python script for generating preliminary designs, available in the online supplementary material)., National Science Foundation (Grants 1609240 and 1610719)

The ultimate current-carrying capacity of high-temperature superconducting (HTS) tapes is extremely important for the design of superconducting devices, especially for superconducting fault current limiter and HTS cables which may be subject to short-circuit overcurrent. In this paper, an HTS tape life characteristics test platform was built, and experiments were carried out on the YBCO tape to study its ultimate current-carrying characteristic under 50 Hz ac current. AC overcurrent amplitude and duration are used as experimental variables. According to the single variable method, the current and voltage of the YBCO tapes under different types of overcurrent were measured. After analyzing and generalizing the test results, the thresholds of its bearable current and corresponding duration are discussed. This paper provides data support and reference for the reliable design of these HTS power devices.

Effects of elastic stress and alternating current (AC) on corrosion behavior of X80 pipeline steel were investigated in a simulated soil solution by electrochemical techniques and surface analysis. Corrosion current density was 40.5 μA/cm2 by synergistic effects of the stress and the AC current, being about five times of that without the stress and the AC current. Corrosion morphology of the steel coupon was pitting corrosion with application of AC current, and changed from pitting corrosion to moat corrosion under effects of the stress and the AC current. Corrosion of the steel coupon was enhanced by increasing anodic dissolution of iron and porosity of corrosion product film.

Compared to conventional transformers, high temperature superconducting (HTS) transformers have higher efficiency and fewer hazards, whose main loss comes from the ac loss of high temperature superconducting windings carrying ac current. Their radial leakage magnetic fields are perpendicular of HTS winding tapes, which is the main parameter affecting the ac loss. In the study of superconducting magnets, the flux diverter has been used to reduce the radial leakage magnetic field. The effect of the flux diverter installed at the top of the transformer windings on the coil ac loss was explored in this paper. The influence of different structure, slotting, and the number of slots on the transformer was also discussed, which laid a theoretical foundation for the optimization of flux diverter on the 6.6 MVA HTS transformers. Besides, in this paper, we choose the homogenization treatment method to reduce the computing time and memory when modeling.

A simple and effective thermal conductivity based CO2 gas sensor has been successfully developed. The CO2 sensor consists of a modified IR thermopile sensor without an IR window. The thermopile is heated by the AC current that is applied through the output terminals of the device, which in turn leads to a temperature gradient generating a DC output voltage. The gas exposed to the thermopile simultaneously cool down the thermopile. Thus, the thermopile can simultaneously serve as a heater and temperature sensor. The built-in sensors possess low production costs, low power consumption and are easily manufactured. From the conducted experiments, the sensor can work well, and the results can be validated with the established theory, as evidenced by the RMS error of 0.787. The measurement results are also in a good agreement with the model predictions Mason and Saxena for the thermal conductivity of gas mixtures.

The paper describes the DC characterization of AC current shunts recently developed at the Faculty of electrical engineering and computing, University of Zagreb (UNIZG-FER). The shunts of cage type design include nine shunts that range from 1 mA up to 10 A. The following DC properties were inspected: long time drift, temperature coefficients and power coefficients. The results have shown that shunts have low temperature (

This paper describes the influence of magnetization of an instrument current transformer (ICT) core on ICT errors, and presents a procedure for demagnetizing an ICT. The dependence of ICT errors on the magnetization of the ICT core for different magnetic materials is given in the paper, together with a detailed procedure for ICT demagnetization. The results of experiments are summarized, and conclusions are drawn on when ICT demagnetization is necessary, and on how to prevent the destruction of an ICT due to its winding being punctured.