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A method using reflected impedance to determine the electrical degradation rates of bioresorbable metals for physically transient electronic devices is outlined. This approach uses known mutual inductor interactions with simple single turn disk coil geometries and a frequency measurement system to track the reduction of the mean thickness of a thin film metal ring as it degrades. Experiments using $\mathrm {500~ \text {n} \text {m} }$ thick zinc rings, fabricated by photolithography, thermal evaporation and lift-off, found a mean degradation rate of 278 nm h−1 in 37 °C de-ionised water. Experiments in 37 °C 1 mM hydrochloric acid found two distinct periods of degradation and a total degradation rate of 632 nm h−1 that closely matched the degradation rate measured using profilometry of 608 nm h−1. [ABSTRACT FROM AUTHOR]

The measurement of high electric field is widely used in applications such as power grid, electrical equipment, space launch, petroleum industry, and meteorological monitoring. Traditional electric field measurement methods, such as field mills, are bulky and cause electric field distortion. In this article, we presented a trampoline-shaped microelectric field sensor (E-sensor) based on microelectromechanical system (MEMS). The micro E-sensor uses the effect of electrostatic induction, which generates force that drives the vibration of a piezoresistive film and converts the electric field into a differential voltage signal. The presented E-sensor can measure both ac and dc high electric fields with relatively high resolution and wide range. Through experimental measurement, the device exhibits an ac resolution of 172 V/m/Hz1/2 and a linear measurable electric field range of 312 V/m to over 700 kV/m. The presented E-sensor has good performance with mm-level size and low cost, which could be mass produced for broad applications. [ABSTRACT FROM AUTHOR]

Field-induced metasurface is an applicable technique to prevent the high-intensity-radiated-field (HIRF). To improve the measurement accuracy, this article presents the design of a waveguide that forms high-intensity TEM waves within its closed transverse boundaries. The proposed quasi-TEM waveguide adopts two artificial magnetic conductors (AMCs) on the sidewalls of a standard rectangular waveguide. And the construction of the AMC is based on the theory of high impedance surface (HIS), which performs perfect magnetic conductor (PMC) properties at its resonant frequency. Then, a prototype is designed and fabricated to measure the electric field distributions and demonstrate the theoretical analysis and simulation. The measurement results indicate that the proposed waveguide could realize a 1 dB rippled electric-field distribution in more than 90% region, compared to that of 30% in the standard waveguide. Finally, high-intensity-field measurements of a field-induced sample, energy selective surface (ESS), are compared in the proposed waveguide and a standard waveguide. The comparison result has proved that the proposed waveguide could better evaluate the HIRF performance of the field-induced metasurface. [ABSTRACT FROM AUTHOR]

In this letter, an innovative technique is presented, which allows the experimental extraction of the junction-to-ambient thermal impedance (ZTH) of power devices operating in their application environment (in situ). The technique draws inspiration from the thermal characterization of RF transistors, and is based on simple measurements of electrical signals, while not requiring a thermochuck, the calibration of a thermometer, as well as temperature sensors or IR cameras. The validation of the technique is unambiguously performed by applying the “simulated experiments” strategy on an SiC-based multichip power module. [ABSTRACT FROM AUTHOR]

It is very desirable to measure both the dielectric breakdown voltage and the dielectric losses in insulating materials at cryogenic temperatures, in order to improve the project of superconducting devices. In this work, we present the project of a measuring system that allows measuring the dielectric breakdown voltage, the loss tangent, and the electric permittivity of dielectric materials samples rated to operate at 77.4 K (liquid nitrogen bath), industrial frequency of 50-60Hz, and voltages up to 13.8 kV. Such system uses the same electrodes and chamber for all those kinds of measurements, in compliance with the standards of those tests. Only the external power and measurement circuits must be changed in order to perform the respective characterization. The project of that measurement system has been validated by computational simulation of a virtual prototype, using a commercial finite element method software package. [ABSTRACT FROM AUTHOR]

In part I of this series article, it was found that a negative charge process after a partial breakdown (PB) could reduce the breakdown voltage of vacuum gaps in series. This part proposes the use of a bridging resistor to mitigate this negative charge process and improve the breakdown voltage of the entire arrangement. Two commercial vacuum interrupters (VIs) of the same model were connected in series, with each VI having a grading capacitor connected in parallel. A bridging resistor was then bridged between two floating potential middle points: at the middle point between the VIs and at the middle point between the grading capacitors. Experiments were performed using various gap distance arrangements and resistance values. A noncontact measurement method using an electric field sensor was proposed to measure the floating potentials of the two VIs. Experimental results showed that the negative charge process could be mitigated using the bridging resistor $R_{g}$ by blocking the discharge current from the grading capacitor into the broken-down VI. The voltage distribution between the two VIs became uneven because of the bridging resistor, but the breakdown voltage of the series-connected gaps increased significantly, regardless of the resistance value. The increase rate was influenced by the gap distance arrangement. With a symmetrical gap distance arrangement for the two VIs, a maximum increase rate of 37.4% was reached when $R_{g} =40\,\,\text{k}\Omega $. With asymmetrical arrangements, when smaller gaps shared higher voltages, the increase rate reached a maximum of 52.8% with $R_{g} =70\,\,\text{k}\Omega $ , but it only reached a maximum of 38.9% when larger gaps shared higher voltages with $R_{g} =10\,\,\text{k}\Omega $. [ABSTRACT FROM AUTHOR]

The measurement of electric field distribution along insulator surfaces plays a vital role in the design of insulators. This article proposes a measuring method of electric field distribution and its image processing algorithm based on electroluminescent effect. Unlike traditional electric field probes, this method is a noncontact measuring method that could reduce electric field distortion along insulator surfaces. There are three main steps: spraying epoxy coating mixed with ZnS:Cu electroluminescent powder on insulator surfaces, photoing luminescence images under different voltages, and deducing the electric field distribution by the proposed image processing algorithm. The surface electric field distributions of three typical insulators used in gas-insulated switchgear/gas-insulated transmission line (GIS/GIL) are measured. Compared with simulation results, the measurement errors of the disk insulator, the basin-type insulator, and the tri-post insulator are less than 2%, 4%, and 2.5%. This method provides a new way of measuring electric field distribution along insulator surfaces. [ABSTRACT FROM AUTHOR]

Gallium nitride (GaN) high-electron-mobility transistor (HEMT) devices, which have wide application potential from power amplifiers to satellite, need to be thoroughly examined in terms of reliability in order to benefit the superior intrinsic properties of the device. The most critical parameter in the device reliability is the hotspot, or ${T}_{\text {max}}$ , which occurs somewhere on the subsurface and along the channel of the GaN HEMT, which is optically inaccessible due to optical path disability. Therefore, the ${T}_{\text {max}}$ value is underestimated in optical measurements, such as the thermographic IR and Raman methods. With 3-D electrothermal simulations, ${T}_{\text {max}}$ is obtained close to reality, but it requires a huge computation load and the complex modeling of semiconductor device physics. In 2-D or 3-D thermal simulations that do not use electrothermal simulations, since the self-heating is mostly modeled with a single heat source, neither the correct ${T}_{\text {max}}$ value is obtained nor the effect of bias conditions is considered. To address the aforementioned shortcomings, a hybrid method is demonstrated, which exploits the electrical measurements of GaN HEMT, which RF and reliability engineers often and easily do. It is demonstrated that ${T}_{\text {max}}$ can be determined quickly and close to the electrothermal simulations in a GaN HEMT device with a two-heat source method and finite element analysis (FEA) hybrid interaction with respect to various bias conditions. Moreover, the impact of the knee voltage is investigated with different knee-detection techniques. The proposed method provides GaN HEMT reliability engineers with an easy-to-implement alternative to reveal the hotspot location and the value. [ABSTRACT FROM AUTHOR]

We experimentally estimate a reduced electric field (${E}/{N}{)}$ of Hermstein’s glow corona discharge from $\text{N}_{{2}}$ intensity ratio: the intensity of the first positive system band (3, 1) [FPS(3, 1)] and the intensity of second positive system band (0, 0) [SPS(0, 0)] are used. The intensity ratio [FPS(3, 1) $/$ SPS(0, 0)] has the relation with the ${E}/{N}$. First, we experimentally clarify the relationship between FPS(3, 1) $/$ SPS(0, 0) and $\text {E}/\text {N}$ at atmospheric pressure. This relationship is acquired by generating the uniform light ionized emission in the parallel-plane gap with the YAG laser and measuring the intensity ratio of FPS(3, 1)/SPS (0, 0) in the range of ${E}/{N} =83.9\,\,\times \,\,10^{-{21}}$ –95.9 $\times \,\,10^{-{21}}$ Vm2. This relationship is applied to Hermstein’s glow corona discharge at atmospheric pressure. As a result, the ${E}/{N}$ of Hermstein’s glow corona discharge is acquired in the range of ${E}/{N} =117.4\,\,\times \,\,10^{-{21}}$ –125.1 $\times \,\,10^{-{21}}$ Vm2. We find the transition of the corona stabilization effect from the discharge occurrence to breakdown by measuring the ${E}/{N}$. This work also considers the gas temperature rise of discharge. Considering the gas temperature rise of discharge has led to the universal method of acquiring the ${E}/{N}$ of discharge from the intensity ratio of FPS(3, 1)/SPS(0, 0). [ABSTRACT FROM AUTHOR]

In Robot Assisted Minimally Invasive Surgery, discriminating critical subsurface structures is essential to make the surgical procedure safer and more efficient. In this paper, a novel robot assisted electrical bio-impedance scanning (RAEIS) system is developed and validated using a series of experiments. The proposed system constructs a tri-polar sensing configuration for tissue homogeneity inspection. Specifically, two robotic forceps are used as electrodes for applying electric current and measuring reciprocal voltages relative to a ground electrode which is placed distal from the measuring site. Compared to existing electrical bioimpedance sensing technology, the proposed system is able to use miniaturized electrodes to measure a site flexibly with enhanced subsurfacial detection capability. This paper presents the concept, the modeling of the sensing method, the hardware design, and the system calibration. Subsequently, a series of experiments are conducted for system evaluation including finite element simulation, saline solution bath experiments and experiments based on ex vivo animal tissues. The experimental results demonstrate that the proposed system can measure the resistivity of the material with high accuracy, and detect a subsurface non-homogeneous object with 100% success rate. The proposed parameters estimation algorithm is able to approximate the resistivity and the depth of the subsurface object effectively with one fast scanning. [ABSTRACT FROM AUTHOR]

This article presents a novel method for measuring the electrical conductivity of metallic materials using a cylindrical resonator. The theory and the process of measuring the electrical conductivity are explained. The cylindrical resonator is designed and proved using full-wave electromagnetic simulations. A prototype operating at 10.5 GHz is fabricated, and the scattering parameters are measured. The quality factor of the cylindrical resonator is calculated at the first step from the measured scattering parameters, and the electrical conductivity of the metallic material is derived using Maxwell's equations. By replacing the top cover of the cylindrical resonator with different materials or metallic sheets, the electrical conductivities can be measured easily. For validating the method, three top covers and six metallic sheets are fabricated and tested. The measured electrical conductivities are compared with other published results and typical values. Besides, by adjusting the operating frequency of the cylindrical resonator, the proposed method can be applied to determine the electrical conductivity at specific frequencies. [ABSTRACT FROM AUTHOR]

Dependence of lightning electric field waveform parameters on distance between the lightning channel and the field measuring point is examined. The analyses are performed based on representative wideband electric field waveforms that were obtained by averaging individual waveforms produced by negative return strokes at distances ranging from 10 to 500 km. The methodology employed for finding the representative waveforms using a large database is described in the companion paper. In this article, we present evolution with distance of the following waveform parameters: zero-to-peak rise time, zero-crossing time, ratio of the initial electric field peak to the opposite polarity overshoot, all for the ground wave, and the ratio of the ground wave initial electric field peak to the peak of the first skywave. We also present a catalog of representative waveforms for different distances, time of day, and stroke order. Additionally, we examine the peak-to-peak and zero-to-zero time intervals between the ground wave and the first skywave that are often used for estimating the apparent ionospheric reflection height. [ABSTRACT FROM AUTHOR]

This article presents a novel measurement and analysis of electromagnetic (EM) information leakage from printed circuit board (PCB) power delivery network (PDN) of cryptographic devices. We propose an accurate EM information leakage analysis method based on a correlation electromagnetic analysis (CEMA) considering advanced encryption standard (AES) operation cycles and clock frequency. We measure field distribution on the PCB level AES core PDN and conduct the proposed analysis method to derive the information leakage maps. For the first time, we verified that the EM information leakage depends on the intensity of dominant field distribution on the PCB PDN using the proposed method. We validated that the whole secret key information can be extracted from locations in the PCB PDN distant from the cryptographic integrated circuit where a specific field is dominant due to the physical structure of the PCB PDN. Based on the measurement and analysis results, we discuss an efficient EM information leakage evaluation method based on the dominant field radiation. We evaluate the EM information leakage from the decoupling capacitor in the backside of the PCB. Finally, we propose a design methodology to suppress the EM information leakage from the PCB PDN. [ABSTRACT FROM AUTHOR]

Due to the large reduction in fossil fuel reservoirs, the consequent cost increase of deepwater extraction, and the emission of pollutants, there is a constant search for alternative ways to obtain clean energy at a lower cost. Among those sources, we focus on the energy produced by thermoelectric materials. In this work, we present a new system for the characterization of thermoelectric generation devices. Such a system performs measurements of electrical resistivity, Seebeck coefficient, and thermal conductivity in a single setup. With this, it is possible to reduce the systematic errors in the figure of merit $ZT$ and the cost of the equipment. Our equipment, together with the developed software, presented excellent results and analyses, and with that, it proves to be a robust alternative for the characterization of commercial thermoelectric devices, and of laboratory thin film thermoelectric materials. [ABSTRACT FROM AUTHOR]

This article presents a highly secure and convenient biometric system for user recognition based on body channel characteristics for electric signal transmission. In the proposed framework, the user can provide reliable biometric features of body channel responses (BCRs) simply by touching an electrode surface on the device with a finger. To realize and verify the proposed approach, we acquired the BCR data from 15 subjects for approximately six weeks through experiments conducted in a customized measurement setup suited to the principle of signal transmission in the human body channel. The proposed BCR-based biometric feature (BBF) comprises a series of envelope vectors of the received BCR when applying up- and down-chirp signals to the human body, which is extracted by an interpolative method based on peak detection. The BBFs are effectively separable according to the subjects because the features magnify quantitative differences in the aspect of path losses and power delay profiles of individual BCRs for the frequency range between 1 and MHz. The classification performance was evaluated by splitting the dataset into ${80\%}$ and 20% for the training and testing, respectively, using conventional machine learning algorithms with uncorrelated 40 session datasets for the respective subjects. The highest average classification accuracy was achieved by the kernel-based support vector machine approximately 95.8% without observable and biased misidentification cases among the subjects. In addition, the analysis of receiver operating characteristic curves shows that the proposed classifiers are robust to decision boundaries at various threshold settings. [ABSTRACT FROM AUTHOR]

This article presents a new method for measuring rms values of alternative current (ac) in power lines using an infrared (IR) camera. An IR camera registers thermal images in time with an appropriate frame rate in order to calculate the spectrum of the temperature signal of a power cable. For the European standard, the amplitudes of the harmonics for $f \approx ~100$ Hz correlate to the power dissipated in a conductor. The fast Fourier transform (FFT) and rms analysis for different current values were performed. The obtained results allow plotting the calibration curve of temperature changes versus the rms values of the current flowing in wire. They confirmed the linear relation between the 100-Hz spectral component of the temperature and the square value of the rms current. This method has unique advantages. It is noncontact and makes it possible to estimate the rms current regardless of the ambient background radiation and convection cooling conditions having a significant impact on overhead lines, in particular. [ABSTRACT FROM AUTHOR]

This article introduces a bias controllable integrated optics electric field measurement system fabricated by LiNbO3 (LN) that can be used for the measurement of 10-kV/m subnanosecond rise time electromagnetic pulse (EMP). Combined with the structure of birefringence modulation (BRM) and the 1550-nm tunable laser, this probe has simple structure measures 1.5 cm $\times 2$ cm $\times4.5$ cm. It realized the set of bias to any value during $2\pi $ with less than 1-nm change of the wavelength of the tunable laser, despite the influence of the environment. Furthermore, an optimal bias automatic feedback controller based on Newton iteration algorithm is constructed to lock the bias at a fixed point. The statistical result (average ± standard deviation) of the bias under controlled is 90.4 ± 0.8°. Calibrated results show that it shows consistent response to the pulse with rise time of 200 ps, and the minimum and maximum measurement amplitude is 0.3 and 45 kV/m, respectively. [ABSTRACT FROM AUTHOR]

The early screening and prevention of chronic respiratory diseases are very important. To achieve the monitoring and management of chronic obstructive pulmonary disease (COPD), this article proposes a new lung impedance measurement method, which uses a cross four-electrode structure. It effectively solves the problems of noncompliance of traditional instruments, risk of cross-infection, and nononline monitoring. Compared with the traditional impedance measurement method, the measurement accuracy of lung function parameters is improved. Using the detection device, the equivalent impedance of the chest was rapidly measured from two orthogonal directions when the people were in the same breath state. The maximum expiratory and inspiratory thoracic impedance was obtained by analyzing 30 samples. The measurement of lung function parameters is realized by solving the change value of impedance and its relationship with the chest circumference. Experiments proved that the cross four-electrode method could consider the two directions of equivalent thoracic impedance, enrich the measurement parameters of thoracic impedance, and make the test results of pulmonary function parameters have good consistency with the results of standard methods. Correlation coefficients of test indexes forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were 0.967 and 0.955 respectively. The consistency boundary diagram showed that more than 95% of monitoring data of the subjects fell within the scope of the consistency boundary, and the maximum relative error of measurement was only 4.65%. [ABSTRACT FROM AUTHOR]

This article presents a standard field generation system with an antenna for the calibration of a Ka-band electric-field probe. We constructed a measurement system having capability of not only rotating the azimuth angle of the probe but also changing the separation distance between the antenna and the probe. As a result, the orientation and separation distance of the probe can be suggested for minimal variation of the measurand, which reduces the overall uncertainty. For traceable electric-field strength measurements, we measured the associated quantities of the power, antenna gain, and impedance of the individual components constituting the field generation system. An evaluation of the uncertainty of the components providing traceability to the system was also conducted. The system is expected to generate a standard field higher than 10 V/m in the frequency range of 26.5–40 GHz. Uncertainty in the correction factors is quantified to determine the factors that affect the calibration, and the expanded uncertainty of the standard field generation system is found to be 5.1% at 26.5 GHz and 5.3% at both 33 and 40 GHz. [ABSTRACT FROM AUTHOR]

In the wireless power transfer (WPT) control system, estimating the coupling coefficient (k) is an essential step to achieving optimal control over a wide charging range. The estimate required signal of the traditional WPT system is mainly the currentand voltage generated by fundamental. It requires many parameters and complex calculations to estimate k by analyzing these electrical signals, which makes the traditional method of estimating k difficult to achieve good robustness and application in practice. To reduce the process of estimation, a method of estimating k only by the harmonic current is proposed in this article. According to this method, a wide charging range WPT control system is designed. The main feature of the control system is that it is very easy to estimate k because the high frequency harmonic can simplify the circuit. By analyzing the system characteristics under different harmonic currents, the system can achieve optimal control over a wider charging range. In addition, a WPT system that meets the Qi standard is designed and tested. The experimental results show that the original 10 mm Qi standard charging distance can reach 20 mm. [ABSTRACT FROM AUTHOR]

In this paper, charge distributions in three-layered epoxy resin and epoxy resin impregnated paper samples under AC and AC-DC superimposed electric fields are measured by the improved high-speed pulsed electro-acoustic system. To exclude the interferences caused by the discontinuity of relative permittivity, a method to distinguish between net dipolar charges and free charges is proposed. Through analysis, the influences of frequency, AC component and DC component on the charge transport and trapping characteristics in multi-layered epoxy composites are obtained, which could provide important reference to the structural design and optimization of converter transformer bushings. [ABSTRACT FROM AUTHOR]

Objective: Electromagnetic recordings are useful for non-invasive measurement of human brain activity. They typically sample electric potentials on the scalp or the magnetic field outside the head using electroencephalography (EEG) or magnetoencephalography (MEG), respectively. EEG and MEG are not, however, symmetric counterparts: EEG samples a scalar field via a line integral over the electric field between two points, while MEG samples projections of a vector-valued field by small sensors. Here we present a unified mathematical formalism for electromagnetic measurements, leading to useful interpretations and signal processing methods for EEG and MEG. Methods: We represent electric and magnetic fields as solutions of Laplace's equation under the quasi-static approximation, each field representable as an expansion of the same vector spherical harmonics (VSH) but differently weighted by electro- and magnetostatic multipole moments, respectively. Results: We observe that the electric and the magnetic fields are mathematically symmetric but couple to the underlying electric source distribution in distinct ways via their corresponding multipole moments, which have concise mathematical forms. The VSH model also allows us to construct linear bases for MEG and EEG for signal processing and analysis, including interference suppression methods and system calibration. Conclusion: The VSH model is a powerful and simple approach for modeling quasi-static electromagnetic fields. Significance: Our formalism provides a unified framework for interpreting resolution questions, and paves the way for new processing and analysis methods. [ABSTRACT FROM AUTHOR]

Human body communications (HBCs) have recently emerged as an innovative alternative to the current radio frequency communications for realizing wireless body area networks (WBANs) using the human body as a transmission channel without wired or wireless connections. This article addresses the provision of reliable modeling of the human body as a passage of the electric signal delivery based on the impulse response measurement through the proposal of a measurement setup and signal processing techniques applicable to wearable devices for healthcare and biosignal acquisition. In the experiments, customized impulse signals were applied to the body using battery-powered devices isolated to the earth ground for the operating environments of wearable devices. The impulse responses passed through the body were measured by considering 52 measurement conditions determined by the device locations from the head to ankle and the body postures. Body channel transfer functions (BCTFs) for the respective conditions were derived by an adaptive filter approach using an iterative algorithm to minimize the mean squared error between the measured and modeled impulse responses. The channel analysis parameters, such as mean path loss, root-mean-square delay spread, and mean and maximum excess delays, were analyzed based on the measured body impulse responses. In addition, the practical bit-error-rate performance for HBC based on the BCTFs reproducing intersymbol interference effects caused by the delay spreads of the body channels was explored to verify communication reliability in terms of the transmitter structures adopting digital transmission, sorts of human body channels, data rates, and operating frequencies. [ABSTRACT FROM AUTHOR]

Contribution: This article has shown that self-efficacy in performing complex computer programming tasks and the self-regulation of electrical and electronics engineering undergraduate students varies with respect to the class standing and prior experience in computer programming. Background: Computer programming is an essential skill that all engineers must possess, as most industries require engineers to own this skill. Prior studies discuss programming self-efficacy (PSE) measures; however, these studies do not specifically measure the PSE of electrical and electronics engineering major in the Indian context. Research Questions: The overarching research question of this article is: What factors related to participants’ demographics, vicarious experiences, and performance accomplishments influence the PSE of electrical and electronics engineering students in India? Methodology: To answer the above research question, a study is conducted using quantitative methods in engineering education research. This article focuses on the development of a survey instrument to measure the PSE of electrical and electronics engineering students of India. The survey includes a total of 31 items, content validity and face validity were established. An exploratory factor analysis was conducted, and the final two factors are “basic programming tasks and dependence” and “complex programming tasks and self-regulation.” A multiple regression analysis was performed to find the best fitting model for the two factors. Findings: The regression model with “basic programming tasks and dependence” was not statistically significant and the regression model with “complex programming tasks and self-regulation” was found to be statistically significant with predictors class standing and prior programming experience. [ABSTRACT FROM AUTHOR]

An “electromagnetic vector sensor” (EMVS) comprises three orthogonal dipoles and three orthogonal loops, all in spatial collocation. The former triplet aims to directly measure the $3 \times 1$ electric-field vector ${\mathbf{e}} $ , whereas the latter triplet aims to directly measure the $3 \times 1$ magnetic-field vector ${\mathbf{h}} $. Their vector cross product $ {\mathbf{e}} \times {\mathbf{h}} $ would yield the incident source’s Poynting vector, which specifies the incident wavefield’s propagation direction. In reality, all these are only an idealization. Instead, a real-world dipole triad’s measurement could equal the incident ${\mathbf{e}} $ , only if the dipoles were electrically short (i.e., with an electrical length of $({L}/{\lambda }) < 0.1$). Likewise, a practical loop triad’s measurement could equal the incident ${\mathbf{h}} $ , only if the loops were electrically small (i.e., with an electrical circumference of $2 \pi ({R}/{\lambda }) < 0.1$). However, such short dipoles and small loops would be electromagnetically inefficient receivers. For a practical dipole that is electrically long, its measurement equals not the incident wavefield’s ${\mathbf{e}} $ but a vector dot product between: 1) the incident wave’s ${\mathbf{e}}$ and 2) that dipole antenna’s “effective length” vector (which depends on that dipole’s $({L}/{\lambda })$ and orientation). An analogous complexity exists for a practical loop that is electrically large. For such practical dipoles and loops, the aforementioned vector-cross-product would fail to yield the Poynting vector, hence it would inaccurately estimate the direction-of-arrival. Instead, this article will advance a new closed-form algorithm to simultaneously estimate an incident source’s direction-of-arrival and polarization, despite the practical dipoles’/ loops’ mathematically complicated gain/phase responses as described earlier, but without any prior knowledge of the dipoles’ electric length $({L}/{\lambda })$ nor the loops’ electric radius $({R}/{\lambda })$. [ABSTRACT FROM AUTHOR]

Ultra-wideband coherent Doppler tomography (UWB-CDT) is a method whereby complex frequency data are evaluated and back-projected at uniform angles around a subject under test (SUT). In the presence of phase shifts brought upon by the unwanted motion in the test equipment, generating a focused image becomes complex due to the nature of the back-projection integration process. This article will demonstrate a vector-based correction algorithm, which can be implemented during the nondestructive evaluation (NDE) of a target to compensate for down-range phase errors (brought upon by the factors external to the ideal measurement setup). This new method will be known as point scatterer vector tracking (PSVT). A coherent image can be constructed by using the returned scattering information contained within a complex time-domain envelope. For the proposed method, multiple vectors based on the estimated peak locations are used to track, correct, and reconstruct the path of an ideal point scatter. The demonstration of the algorithm with measured tomographic data combined with a simulated additive noise component is presented, along with a step-by-step approach to reconstruct the desired data set. It will be shown that by using this proposed method, a coherent CDT image with an average correlation coefficient of 0.71 can be recovered from the data that have been corrupted by the unwanted phase shifts. [ABSTRACT FROM AUTHOR]

This paper develops an approach for household appliance identification and classification of household activities of daily living (ADLs) using residential smart meter data. The process of household appliance identification, i.e., decomposing a mains electricity measurement into each of its constituent individual appliances, is a very challenging classification problem. Recent advances have made deep learning a dominant approach for classification in fields, such as image processing and speech recognition. This paper presents a deep learning approach based on multilayer, feedforward neural networks that can identify common household electrical appliances from a typical household smart meter measurement. The performance of this approach is tested and validated using publicly available smart meter data sets. The identified appliances are then mapped to household activities, or ADLs. The resulting ADL classifier can provide insights into the behavior of the household occupants, which has a number of applications in the energy domain and in other fields. [ABSTRACT FROM AUTHOR]

A study of deep levels in CdZnTeSe radiation-detection materials is presented. The approach relies on electrical methods that combine time and temperature evolution of the electric field and electric current after switching on the bias voltage. Two optical methods were also applied to study the deep levels. The first method utilizes the temperature and temporal analysis of the electric field evolution after switching off an additional light illuminating the sample at a wavelength of 940 nm. The second method involved measuring of the electric field spectral dependence during near infrared illumination. The results are compared with those obtained with the high-quality CdZnTe detector-grade material. We conclude that the introduction of Se into the lattice leads to a shift of the second ionization level of the Cd vacancy toward the conduction band, as predicted recently by first-principles calculations based on screened hybrid functionals. [ABSTRACT FROM AUTHOR]

In this work, composite materials with nonlinear conductivity are used to enable grading of the electric field distribution along polymeric outdoor insulators, particularly near the high-voltage and ground terminals. A ZnO spherical microvaristor/carbon fiber (CF)/ silicone rubber (SR) composite is used as the field grading material (FGM). Finite element method-based numerical simulations are performed to analyze the electric field distributions of 220 and 500 kV composite insulators when the nonlinear conductivity type composite material is used. The 220 and 500 kV composite insulators are fabricated based on the results of the simulations and optical electric field sensors are used to measure their electric field distributions under normal operating conditions. The electric field distribution along the composite insulators are shown to be improved through use of the FGM, and the simulation results are consistent with the experimental results. These graded electric field distributions may reduce the degradation of the polymer materials used in composite insulators and extend their lifetimes. In addition, the dry flashover voltages of insulators with FGMs are higher than those of traditional insulators. [ABSTRACT FROM AUTHOR]

This paper presents a new estimation technique with $K$ -order expressions for evaluating the maximum electric fields radiated from multiple-antenna transmitters such as those in mobile phones, WiFi access points, and cellphone base stations. The need for $K$ -order estimation to provide precisely estimated electric fields, then develop useful expressions for the estimation and validate the estimation model numerically and experimentally is explained. Fundamental concepts of estimation and detailed electric field formulas, applied to various measurement systems using vector or scalar E-field probes, are presented. Several validations are also illustrated. As a result, it is verified that $K$ -order estimations significantly reduce the differences between the estimated and simulated/measured E-fields [or specific absorption rates (SARs)]. Investigations on the maximum electric fields of two antennas operating at 2.5 GHz in an ordinary room show that the maximum difference between the electric fields obtained by conventional estimations and calculations can be 8.5%, which is suppressed to below 0.24% and 0.02% by 2- and 3-order estimations, respectively. Similarly, in evaluations of the SAR of a three-antenna configuration, the maximum difference between the estimated and calculated SARs of about 5% obtained by conventional estimations is reduced to 0.1% or 0.01% by 2- and 3-order estimations, respectively. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel method that utilizes amplitude-only data of the electric field over a completely closed surface for the reconstruction of the spherical electric field, which represents a radiation source or an antenna under test (AUT) in the near-field (NF) region. The electric field exploiting genetic algorithm (GA) for global optimization is originally derived from a random initial estimate of field distribution and will gradually approximate to the exact value during iterations. When GA reaches the convergence criterion, we can calculate the far field (FF) by spherical NF-to-FF (NF-FF) transformation. The simulated and numerical results are in good agreement with each other, which shows that this method is effective over one or two closed surfaces. Furthermore, the related discussions corresponding to GA are given, confirming that the improved GA is feasible and efficient. [ABSTRACT FROM AUTHOR]

This paper analyses the inherent difficulties in measuring the horizontal electric field from lightning and proposes some solutions to mitigate the contamination effect of the overwhelming vertical electric field. The analysis is carried out with a set of time-domain equations for the calculation of the electromagnetic fields from lightning. As these equations are scattered in several publications, in this paper they are compiled and presented in a harmonized form. Moreover, one new expression for the vertical electric field slightly below the ground surface is presented. It is shown that the horizontal electric field at the surface of lossy ground can be measured with minimum disturbance caused by the vertical electric field if the field sensor is placed slightly below the ground surface. This paper also shows that the horizontal electric field above the ground surface could be measured with the help of a pair of field sensors conveniently arranged so that the influence of the vertical electric field on the measurement is cancelled. [ABSTRACT FROM AUTHOR]

In this paper, we consider the problem of estimating the parameters of a Poisson arrival process, where the intensity function is assumed to lie in the span of a known basis. Our goal is to estimate the basis expansions coefficients given a realization of this process. We establish novel guarantees concerning the accuracy achieved by the maximum likelihood estimate. Our initial result is near-optimal, with the exception of an undesirable dependence on the dynamic range of the intensity function. We then show how to remove this dependence through a process of “noise regularization,” which results in an improved bound under our analysis. We conjecture that a similar guarantee should be possible when using a more direct (deterministic) regularization scheme. We conclude with a discussion of practical applications and an empirical examination of the proposed regularization schemes. [ABSTRACT FROM AUTHOR]

Far-field measurements of lightning-produced electromagnetic fields are of high importance for lightning location systems. Data from recorded lightning strokes can be, for example, used to assess the risk of lightning-induced damage in some geographical areas. Artificially triggered lightning, usually generated using rocket-wire technology, plays an important role in the study of lightning physics. Multiple-station observations of far (typically larger than 20 km) electric field waveforms produced by rocket-triggered lightning are quite rare. In 2014, electric field waveforms were measured for return strokes through the rocket-and-wire technique at Conghua. They were measured by electric field sensors at nine sites belonging to the lightning locating system in Foshan, Guangzhou, China. A total of 38 events were recorded and overall statistics of those waveforms are presented. The results were compared to previous experimental data related to natural and artificially triggered lightning to validate their similarity. [ABSTRACT FROM AUTHOR]

Recent upgrades of the low-cost lightning detection and waveform storage system (LDWSS) are presented. The system has been developed for research and operational use in the Amazon region of Brazil and it has been in operation in this region since November 1, 2017. The original version of the LDWSS operated for 10 months at the Lightning Observatory in Gainesville, Florida, where it was calibrated and tested. Two main modifications implemented include the improvement of the effective dynamic range and the capability to detect lightning in different frequency bands. The improvements were achieved by using two pre-amplifiers working in parallel, a new processing (smart saving) algorithm, and programmable analog filters. As a result, a single, low-cost lightning electric field measuring system allows one to record both close and far lightning events with good amplitude resolution and without saturation, and study both wideband and narrow-band (for example, very low frequency) field signatures of lightning, without modifying the hardware. [ABSTRACT FROM AUTHOR]

Intense transient electric-field measurements underlie much of the basic research in various fields of science and technology. In this paper, an optical sensor with a conjugate compensation configuration of a dual crystal is proposed that appears suitable over a broad range of temperatures. A test platform is constructed to obtain the temperature-dependent characteristics of the designed sensor, including the transfer function, the linear measurement range, and the frequency response. A piecewise transfer function corresponding to ambient temperatures is proposed enabling a maximum measurement error of less than 5% over a wide range of temperatures (-10 to 50 °C) for electric fields of frequencies ranging from 10 Hz to 1 MHz and intensities ranging from 1.2 to 155 kV/m. Applications using this sensor in measuring transient electric-field intensities confirmed that the sensor is expected to find widespread use in measurements of intense transient electric fields. [ABSTRACT FROM AUTHOR]

Entropy-based divergence measures have proven their effectiveness in many areas of computer vision and pattern recognition. However, the complexity of their implementation might be prohibitive in resource-limited applications, as they require estimates of probability densities which are expensive to compute directly for high-dimensional data. In this paper, we investigate the usage of a non-parametric distribution-free metric, known as the Henze–Penrose test statistic to obtain bounds for the $k$ -nearest neighbors ($k$ -NN) classification accuracy. Simulation results demonstrate the effectiveness and the reliability of this metric in estimating the inter-class separability. In addition, the proposed bounds on the $k$ -NN classification are exploited for evaluating the efficacy of different pre-processing techniques as well as selecting the least number of features that would achieve the desired classification performance. [ABSTRACT FROM AUTHOR]

For the development of HVDC electrical insulation performance in liquid dielectric systems such as oil-pressboard (PB) composite systems in DC converter transformers, a Kerr electro-optic electric field measurement (Kerr-EOM) technique has been well established and will be considered as the key technique to be introduced. In this paper, the Kerr-EOM was experimentally applied to identify the electric field stress distribution and clarify charging activities in oil/PB composite insulation systems, under HVDC and DC polarity reversal (DC-PR) conditions. The physical mechanisms of charge movement and the amount of charge accumulation in liquid/solid insulation systems are also thoroughly investigated and discussed. Moreover, the breakdown discharge initiation by accumulated charges on the PB was observed and discussed together with the field measurement results. Secondly, by combining the Kerr-EOM with the electric field analysis using the Finite Element Method (FEM), the enhancement of the electrical insulation performance for HVDC applications was discussed and the critical testing voltage conditions in DC converter transformers were addressed. This paper is based on the Hans Tropper Memorial Lecture given at the IEEE DEIS, International Conference on Dielectric Liquids (ICDL) in 2017 in Manchester, UK. [ABSTRACT FROM AUTHOR]

Underwater object detection and tracking are of considerable interest in offshore defense. Recently, a new method that takes advantage of direct-current resistivity survey techniques has been introduced as a complement to the conventional detection method for use in acoustically noisy conditions. However, dedicated rapid target localization methods are required to enable real-time tracking in this detection method. Therefore, in this paper, we propose a real-time localization method using grid-based template matching. The main features of our method are as follows: 1) measurement data sets from two separate detection lines are used; 2) template matching based on correlation is used; 3) the templates are precalculated by numerical modeling; and 4) real-time localization processing is implemented by efficient calculations. To verify our method, we first performed experiments for stationary target object positions under a water tank condition: template versus numerical modeling data and template versus physical modeling data. Next, real-time localization experiments for a moving target in the water tank were conducted using the real-time data at 3-Hz refresh rate. In the real-time experiments, we confirmed that the estimated positions could keep track of the actual target positions continuously. We expect that this paper will contribute positively to offshore defense and surveillance. [ABSTRACT FROM AUTHOR]

Wide-area monitoring of power systems is important for system security and stability. It involves the detection and localization of power system disturbances. However, the oscillatory trends and noise in electrical measurements often mask disturbances, making wide-area monitoring a challenging task. This paper presents a wide-area monitoring method to detect and locate power system disturbances by combining multivariate analysis known as Principal Component Analysis (PCA) and time series analysis known as $k$ -Nearest Neighbor ($k{\text{NN}}$) analysis. Advantages of this method are that it can not only analyze a large number of wide-area variables in real time but also can reduce the masking effect of the oscillatory trends and noise on disturbances. Case studies conducted on data from a four-variable numerical model and the New England power system model demonstrate the effectiveness of this method. [ABSTRACT FROM AUTHOR]

An electrical signature analysis (ESA)-based method to detect bearing defects in electromechanical drivetrains (e.g., wind turbines) is proposed in this paper. The novelty of the proposed technique is justified by its capability to detect a defect that occurs in a drivetrain bearing, external to the machine. Unlike the traditional vibration-based method, the electrical measurements of the terminal machine are utilized in this case to perform the fault detection. The proposed ESA-based method is developed utilizing a new electrical signal model of bearing defect, proposed in this paper, based on the excitation of torsional resonances. The proposed ESA-based method and the signal model are validated through experimental tests. The proposed technique demonstrates excellent fault detection capability even at low operating speed, which is advantageous over the traditional vibration-based method in terms of sensor cost, installation complexity, and detection reliability. [ABSTRACT FROM PUBLISHER]

A novel, highly sensitive dual-parameter sensor based on tandem-interferometric arrangement of Fabry–Pérot interferometer and Mach–Zehnder interferometer (MZI) has been designed and implemented in this paper. The sensor is composed of a single-mode fiber (SMF), hollow-core fiber, no-core fiber (NCF), and photonic crystal fiber (PCF). Those can simultaneously form a Fabry–Pérot interferometer and a MZI. The both interferometers are able to measure strain. Meanwhile, the PCF was filled with liquid crystal to measure electric field intensity. Hence, simultaneous measurement of electric field and strain can be achieved. The sensitivities of electric field and strain can reach up to 10.5 nm/(kV/mm) and 1.25 pm/ $\mu \varepsilon $ , respectively. [ABSTRACT FROM PUBLISHER]

The design and implementation studies of a real time monitoring and smart metering system are presented in this study. The proposed design is improved in terms of smart metering infrastructure based on current, voltage, and power measurements. The communication among the string inverter and host PC is performed by the designed ZigBee transceiver system. Sensing circuits are the most significant devices for measuring both current and voltage magnitudes of the systems. The measured data are processed by the microcontroller unit (MCU) and are modulated after signal processing operations for serial communication. Although the transceiver is configured to execute bi-directional communication, unidirectional data flow is performed where the smart metering system transmits data to monitoring substructure. The monitoring software is also implemented in the context of the presented study. The Visual Studio software development kit is used to design and to code the software by using C#. The performed experimental studies showed that the proposed real time monitoring and smart metering system could be exploited to monitor current, voltage and power magnitudes of the string inverters in an efficient way. [ABSTRACT FROM AUTHOR]

A new spherical field transformation approach for near-field measurements above perfectly electrically conducting (PEC) ground planes at arbitrary heights is presented. It provides higher order probe correction and treatment of irregular sample point locations on the measurement surface but has the same low computational complexity as the known fast Fourier transform (FFT) accelerated spherical field transformation with first-order probe correction. The infinite PEC boundary is considered by applying the image principle to the spherical modes of the device under test (DUT). Only the measurements above the ground are required to iteratively solve the inverse problem for the unknown spherical mode coefficients. Due to additional modal translation operators, the scan center of the spherical measurement system does not need to lie in the ground plane. Moreover, if the DUT is positioned at an appropriate height above the ground plane, the free-space sources of the DUT are extractable with good accuracy. By employing the nonequispaced FFT, the near field can be irregularly sampled on the spherical measurement surface. Numerical investigations show the capabilities of the proposed field transformation approach. Its practical relevance and efficiency are demonstrated for simulated automotive antenna measurements and real near-field measurements above a metallic ground. [ABSTRACT FROM PUBLISHER]

Measuring the shielding effectiveness (SE) of physically small but electrically large enclosures is an important concern in electronics industry. In recent years, reverberation chambers (RCs) are becoming prevalent in determining the SE of such enclosures. Conventionally, frequency-domain (FD) measurement is adopted. It requires three antennas (one transmitting antenna and one receiving antenna in the large RC and one receiving antenna in the nested small enclosure). Furthermore, to obtain good accuracy, the knowledge of the efficiency of the two receiving antennas is also required. To promote the industrial application of RCs for SE measurement, simplified methods are desired. In this paper, simplified measurement methods are proposed and studied both in the FD and the time domain (TD). Only two antennas are required in the proposed methods. Thus, the measurement setup is greatly simplified. It is found that in the TD, a fast and accurate measurement method can be realized with the simplified measurement setup. Moreover, the measurement simplification can go a step further by replacing the RC with an electrically large metallic enclosure in the TD. The measurement results demonstrate that the TD approach outperforms the FD approach in many ways. The proposed methods have the merits of high efficiency, good accuracy, and simple measurement setups. They are very suitable for SE measurement of electrically large enclosures. [ABSTRACT FROM PUBLISHER]

A test procedure is described in this paper that is conceived to investigate the degradation mechanism of PhotoVoltaic (PV) modules subjected to different stress quantities. The procedure is based on the application of environmental and mechanical stress quantities to the modules under investigation and on the electrical and optical characterization of the same modules. The measurement technique implemented to estimate the maximum power at Standard Test Conditions (STC) of the PV modules is deeply investigated in order to estimate the 95% confidence interval of the estimated parameter. Preliminary results are also reported that refer to the application of the proposed test procedures to two sets of p-Si modules. [ABSTRACT FROM AUTHOR]

Impulse breakdown test results show the breakdown strengths of propylene carbonate modified by Al2O3 nanoparticles and Fe3O4 nanoparticles are improved by 13 % and 20 % than that of propylene carbonate without nano-modification, respectively. In order to explore the nano-modification mechanism, the electric field and space charge distributions in propylene carbonate with and without nano-modification were measured through a modified Kerr electro-optic measurement method. The measurement results show the space charge densities are decreased and the space charge transportations are inhibited in PC-based nanofluids compared with that of pure propylene carbonate due to the space charge adsorption of nanoparticle. Therefore, the streamer propagation in nanofluids is impeded, and the breakdown voltage is improved. The calculation of electric potential outside the nanoparticle indicates that Fe3O4 nanoparticle has stronger space charge adsorption capacity than Al2O3 nanoparticle. Accordingly, the Fe3O4-modified propylene carbonate shows greater improvement of breakdown performance than Al2O3-modified propylene carbonate. [ABSTRACT FROM PUBLISHER]

Calibration with a monocone on a ground plane (CALMOPLA) is a tool for the calibration of low-sensitivity and ultrawideband (UWB) electric or magnetic field probes. It consists of a small conical monopole (D-dot), positioned in the center of a ground plane and emitting electromagnetic waves. Close to the reference plane, the radiated signals are quasi-spherical waves which can be described by well-known analytical expressions. The originality of the CALMOPLA calibration method consists in radiating at once spherical waves at UWB frequencies (from several tens of megahertz to several gigahertz) with a unique emitter, in free-field (377- $\Omega $ impedance), in delivering a signal amplitude usable for low-sensitivity sensor calibration, and this with reasonable geometrical dimensions. A vector network analyzer is sufficient to cover the frequency range of most of the sensors to be calibrated. Nevertheless, the use of a low-noise amplifier and a low-frequency power amplifier allows the measurement range to be extended to a very low-sensitivity sensor anywhere on CALMOPLA. [ABSTRACT FROM PUBLISHER]

In an electricity market, the main goal of a generation company (GenCo) is to maximize its profit, while encountering the uncertainty of the electricity price forecast. Different risk measures have been proposed to cope with this source of uncertainty. However, those are usually before-the-fact performance indices and cannot give a measure for the financial loss/gain (FLG) of a GenCo considering the electricity prices actually realized in the market. This paper focuses on this matter. The time series of FLG is first constructed given the real conditions of the electricity market. Then, the FLG time series is quantized using Silhouette criterion and k-means clustering approach. Subsequently, based on the historical values of the quantized FLG time series and relevant exogenous variables, its day-ahead values are predicted. The method proposed for day-ahead FLG prediction consist of conditional mutual information and sequential forward search as the feature selection technique and extreme learning machine as the forecasting engine. The effectiveness of the whole proposed approach, including the FLG time series construction, quantization approach, and the prediction method, is shown for a typical GenCo using the real data of the PJM and Ontario electricity markets. [ABSTRACT FROM PUBLISHER]