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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]

Cranial microsurgery is a prerequisite for neuroscience research, which provides an accessible brain for neural recording and optogenetic stimulation. As the scale of electrode implantation increases, massive delicate craniotomies are required to perform on the submillimeter-thick skull of small animals (e.g., mice). Automated craniotomy (AMC) is ideal for improving surgery efficiency and ensuring consistent results. However, due to the lack of effective feedback, the current AMC platforms are prone to over-drilling and injuring brain tissues. Fragile and ultrathin skulls of small objects also make it hard to integrate suitable sensors into the end-effector for accurate perception. Thus, this article proposes an integrated electrical bioimpedance measurement (EBIM) solution for the closed-loop AMC. A sensing drill and a custom EBIM device are implemented to form reliable electrical contact with the object and accurately measure the impedance. After evaluating the EBIM device’s accuracy (< 2% relative error) and stability, we provide a modified judgment signal for breakthrough detection and further simulate closed-loop craniotomies on an equivalent model. The experimental results demonstrate that the proposed system can achieve sensitive breakthrough detection (< 0.1 s delay at 100 Hz excitation) and consistent drilling depth ($10.3 \mu \text{m}$ deviation with a 10-mm/min feed rate) in contrast to the gold standard (LCR meter). [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]

This is the first time that the feasibility of space charge measurements on full-sized HVDC cable joints has been explicitly considered. In this article we also consider whether the PEA and TSM techniques could be used. [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]

With the development of Internet of Things technology and artificial intelligence, the electric field sensor is required to be miniaturized, high performance, and low cost. At present, the commercial use of electric field sensing technology is facing several limitations, such as dynamic range, bandwidth, size, and signal-to-noise ratio. In this paper, a novel integrated waveguide wide-band electric field sensing solution is proposed. Based on the evanescent field and electro-optic effects, the high efficiency electro-optic energy coupling between the micro-ring resonator and the electro-optic polymer film is realized. Further, the information of the applied electric field is obtained by detecting the output light intensity of the Mach-Zehnder interferometer. The sensor can measure the electric field efficiently over a wide frequency band (50 Hz–13.5 MHz) and maintains good temperature stability. The sensor is small in size, simple in structure, low in cost, and easy to integrate. In addition, the sensor has the capability to realize the functions such as atmospheric electric field monitoring and lightning warning, providing a technical foundation for the construction of the Internet of Things. [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 realistic power system state estimation, the distribution of measurement noise is usually assumed to be Gaussian while many researcher have verified that it can be non-Gaussian. In this paper, a new robust state estimator based on exponential absolute value function is proposed to address the non-Gaussian measurement noise and outliers. The influence function, a robust statistics tool, is used to obtain the state estimates to reduce its computational burden. A state estimation mean squared error formula of the proposed robust estimator is derived which can be used as a reference in the wide area monitoring system design or upgrade. Simulation results obtained from the IEEE 30-bus, 118-bus and 300-bus systems verify the effectiveness and robustness of the proposed robust estimator. [ABSTRACT FROM AUTHOR]

In this article, the author discusses the reproducibility of the fire and flash point measurements of unused liquids. The results are also presented following laboratory-based aging studies, either under sealed or partially open conditions. [ABSTRACT FROM AUTHOR]

This study aims to develop a novel wavelet neural-network (WNN) model for solving electrical resistivity imaging (ERI) inversion with massive amounts of measured data in control and measurement fields. In the proposed method, we design a mixed multilayer WNN (MMWNN) which uses Morlet and Mexican wavelons as different activation functions in a cascaded hidden layer structure. Meanwhile, a hybrid STGWO-GD learning approach is used to improve the learning ability of the MMWNN, which is a combination of the self-tuning grey wolf optimizer (STGWO) and the gradient descent (GD) algorithm adopting the advantages of each other. Moreover, updating formulas of the GD algorithm are derived, and a Gaussian updating operator with weighted hierarchical hunting, a chaotic oscillation equation, and a nonlinear modulation coefficient are introduced to improve the hierarchical hunting and the control parameter adjustment of the modified STGWO. Five examples are used with the aim of assessing the availability and feasibility of the proposed inversion method. The inversion results are promising and show that the introduced method is superior to other competitors in terms of inversion accuracy and computational efficiency. Furthermore, the effectiveness of the proposed method is demonstrated over a classical benchmark successfully. [ABSTRACT FROM AUTHOR]

Iatrogenic facial nerve injury often occurs during parotidectomy owing to the difficulty associated with accurately locating the facial nerve from adjacent tissues (parotid gland and muscle). This injury causes postoperative facial nerve dysfunction, leading to functional and/or cosmetic problems. In this study, we propose an in-vivo detection method to distinguish the facial nerve from the adjacent tissues using electrochemical impedance spectroscopy (EIS). The electrical impedance of the facial nerve, parotid gland, and muscle via in-vivo experiments using guinea pigs (n = 3) was measured using microelectrodes on polyimide film (MoP), consisting of detection and connection parts. The connection part was selectively coated with a photoresist that exhibits high resistivity to attenuate a distortion of the sensor output. Statistically significant differences in impedance of the real and imaginary parts were observed between the facial nerve and the adjacent tissues in the frequency range of 0.99 kHz to 1 MHz (p-value < 0.05, t-test). Optimal frequency, where the difference between adjacent tissues and facial nerve had the most distinction, were 13.64 kHz in the imaginary part of impedance. Additionally, the estimated electrical properties (conductivity and permittivity) of the facial nerve and adjacent tissues were statistically distinguishable (p-value < 0.05, t-test). These findings indicate that MoP with EIS could enable surgeons to easily locate the facial nerve during parotidectomy. [ABSTRACT FROM AUTHOR]

For accommodating rapidly increasing power demands, power systems are transitioning from analog systems to systems with increasing digital control and communications. Although this modernization brings many far-reaching benefits, the hardware and software newly incorporated into the power systems also incur many vulnerabilities. By taking advantage of these vulnerabilities, adversaries can launch various cyber/physical attacks to tamper with electricity meter readings, i.e., to steal electricity. It is reported that total worldwide annual economic losses caused by electricity theft reached up to almost one hundred billion dollars in recent years. With methods to tamper with meter readings becoming more versatile, secret, and flexible, electricity theft tends to get even more serious in modernized power systems. For preventing adversaries from stealing electricity, researchers have done a lot of works. Although some related surveys on these works exist, they are not updated or just discuss electricity theft in a specific region. This survey aims to gain a comprehensive and in-depth understanding of the electricity theft issue. After investigating how adversaries tamper with meter readings, we systematically survey all existing detection methods up to date, which is classified into machine learning- and measurement mismatch-based methods. Adverse effects and political and socioeconomic factors of electricity theft are also provided. This survey can help relevant researchers to shape future research directions, especially in the area of developing new effective electricity theft detection methods. [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]

Horizontal gas-liquid two-phase flows widely exist in petroleum, chemical, and other important industrial fields. The flow structures forming during gas-liquid flows can be complex. The transition between flow patterns greatly depends on many factors, such as the fluid properties and the flow rate. Notably, there are multi-scale flow structures even in the same flow pattern. Therefore, it is a great challenge to accurately measure the gas holdup in the horizontal gas-liquid flows by single-mode sensor technology. In this study, we designed a novel combined ultrasonic-conductance sensor (CUCS) consisting of a multi-electrode conductance sensor (MCS) and a transmission ultrasonic sensor (TUS). A flow pattern map of the horizontal gas-liquid flow was obtained in the experiment, and the responses of the CUCS under different flow patterns were collected. The stratified smooth (ST) flow, stratified wavy (SW) flow, and Taylor bubbles in intermittent flow were visualized by the MCS, and the corresponding measurement model of the gas holdup was presented. For the slug region (SR) in intermittent flow, a physical model for measuring the gas holdup was established based on the attenuation characteristics of the transmitted ultrasonic wave. The result indicates that the CUCS has a higher measurement accuracy for the gas holdup of the horizontal gas-liquid flows with different flow patterns. [ABSTRACT FROM AUTHOR]

The impedance flow sensors have usually been considered as the competitive components in the multi-flow measurement, primarily due to their advantages of fast response, high dynamic range and sensitivity, non-invasive and/or non-intrusive measurements. In this review, the impedance sensors have been categorized into two categories, i.e., the probes for local/average parameter measurement and sensor arrays for distributed parameter measurement. Maxwell’s equations and boundary conditions have been referred as a starting point to understand the measuring principle of impedance sensors, from which the sensitivity distribution can be attained. The sensitivity distribution can be utilized to characterize the sensor and employed as an objective function in optimizing the sensor geometry. The EMA models usually offer a way to relate the impedance measurements to individual phase fraction, which have been critically reviewed. In addition, the application range, spatial and temporal resolutions, advantages and disadvantages of the sensor arrays, i.e., the wire mesh sensor, field focusing sensor, electrical resistance and capacitance tomography sensors have also been provided. Finally, the future trends of impedance sensor development have been briefly discussed. [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 provides one of the first comprehensive reviews of tissue-emulating phantoms available for the in vitro experimentation of radio-frequency (RF) antennas and other electromagnetic (EM) components. Diverse recipes and formulation approaches are available in the literature for such phantoms, but a holistic overview has yet to be reported. We review RF phantoms based on their textures (i.e., liquid, semisolid, and solid) and briefly discuss the use of readily available animal tissues for in vitro experimentation. For each phantom group, we present an overview of the various recipes and fabrication methods, specify the operating frequency range and tissue(s) they emulate, discuss the associated benefits and challenges, and summarize the wireless applications for which they have been employed to date. Further, we review various methods available in the literature to measure the electrical and thermal properties of RF phantoms as required to verify their tissue-emulating capabilities. This review creates a comprehensive resource for ongoing and future studies in the field and is intended to stimulate future research in the development of tissue-emulating phantoms and wireless RF components operating in, on, or near the body. [ABSTRACT FROM AUTHOR]

Capacitive non-contact imaging of electric fields and potentials with micro-metre resolution can provide relevant insights into material characterisation, structural analysis, electrostatic charge imaging and bio-sensing applications. However, scanning electric potential microscopes have been confined to rigid and single-probe devices, making them slow, prone to mechanical damage and complex to fabricate. In this work, we present the design and characterisation of a novel 5-element flexible array of electric potential probes with spatial resolution down to 20 $\mu \text{m}$ to speed up the scanning time. This was achieved by combining flexible thin-film probes for active guarding and shielding with state-of-the art discrete conditioning circuits. The potential of this approach is showcased by using the fabricated array to image latent fingerprints deposited on an insulating surface by contact electrification, obtain the surface topography of conductive samples and to visualise local dielectric variations. [ABSTRACT FROM AUTHOR]

The measurement of an electric field is of great significance for applications such as online monitoring and fault diagnosis in the ubiquitous power Internet of Things (UPIoT), meteorological monitoring, the petrochemical industry, and space launches. Traditional electric field measurement methods, such as field mills, are bulky, cause electric field distortion, and have a strong temperature dependence. Micro electric field sensors (E-sensors) can effectively reduce the distortion of electric fields. Meanwhile, the low cost and small size allow micro E-sensors to be installed inside equipment, and they are suitable for large-scale sensor array applications. This article introduces E-sensors based on different principles, including the electro-optic effect, induced charge, the inverse piezoelectric effect, and so on. The applications of micro E-sensors and the challenges faced by electric field measurement are also introduced. [ABSTRACT FROM AUTHOR]

The debate over whether electromagnetic fields (EMFs) exposure poses a danger to human health is recurring and goes back centuries to when our society first began to rely on electricity. [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]

In this letter, 5 nm-thick HZO ultra-thin ferroelectric capacitors with excellent remanent polarization (Pr) and reliability are presented. The TiN/HZO/TiN metal-ferroelectric-metal (MFM) capacitor stack was deposited consecutively in the same atomic layer deposition (ALD) system without breaking the vacuum (i.e. “in-situ” like) to improve the interface quality between TiN electrodes and HZO ferroelectric layer. The samples show high Pr of 20.5 μC /cm2 (i.e. 2Pr = 41 μC/cm2) under driving voltage of 3 V with low coercive voltage of approximately 0.6 V. The robustness of the MFM capacitor was presented by the outstanding endurance characteristics for keeping 2Pr value higher than 20 μC/cm2 after 1010 cycles at a high electric field of 5 MV/cm without breakdown, though the Pr values gradually degrade with cycles at low field (i.e. 2.4 MV/cm). The highly robust endurance characteristics of the 5nm-thick HZO MFM capacitor indicate the good interface quality achieved in this study. [ABSTRACT FROM AUTHOR]

Moisture distribution information is a critical element in drying processes. The drying of products by employing high-power microwave (MW) technology is widely used in the industry. Although microwaves allow volumetric and selective heating resulting in a significant reduction of processing time and energy consumption, there is always a risk of non-uniform moisture distribution in the final product. This paper investigates the capability of a designed electrical capacitance tomography (ECT) sensor to estimate the moisture distribution of polymer foams in a microwave drying process. The moisture distribution is estimated based on the non-intrusive contactless measurements of the electrical capacitances between the electrodes mounted on a frame around the target polymer foam. The obtained moisture information can be employed as feedback to a controller to adjust the power level of each microwave source in the microwave system to reduce or eliminate the non-homogeneity of the moisture distribution inside the polymer foam. In a series of experiments, we first examine the capability of the ECT sensor in estimating the moisture distribution in a stationary foam. We extend the tests to estimating the moisture distribution in a case where the foam is moving on a conveyor belt. Several study variables are taken, including the sample size, the sample location, the moisture percentage, the conveyor belt speed, and the microwave power. These experiments show that the sensor has a satisfactory accuracy in estimating the moisture distribution of the foam, and the ECT measurements can be further used in a closed-loop control system. [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]

High-altitude electric fields are a critical parameter of electricity in the atmosphere. Due to such drawbacks as their bulk and high cost, traditional electric field mills are not available for daily atmospheric sounding purposes. This paper introduces a highly sensitive and robust electric field sounding sensor based on an existent micro-electro-mechanical systems chip and a new protective package that augments sensor sensitivity. To gain high sensitivity, an innovative external metal electrode connects to the electric field microchip’s package cap, hangs down out of the guardian foam, and effectively enhances the local electric field near the microchip due to the distortion effect. This distortion regularity was studied during a series of finite element simulations, calibrations, and comparison experiments. With a 1.5-meter-long external electrode, the sensitivity of the sensor reached 465 mV/kV/m with a resolution that was better than 10 V/m in an actual long-term ground comparison test. Furthermore, the microsensor chip and its circuit are protected inside a foam while the metal electrode is exposed outside, therefore gaining a robust stability during harsh environments such as low temperature, rainfall, etc. To examine the performances, we built an electric field sounding system, including the electric field sensor, a radiosonde, and a receiving antenna, and measured high-altitude electric fields in various weather conditions. Intended for atmospheric electricity research, our innovative electric field sounding sensor would be especially propitious if integrated with a radiosonde and applicable to daily sounding services. [ABSTRACT FROM AUTHOR]

An electric field measurement system with two optical pulse sources down-converts the high-frequency electric signal to the baseband through a probe exploiting the electro optic-effect. From that process, it is feasible to recover the measured frequency. However, the majority of the current studies focus on the case where the difference between the two repetition frequencies is quite small, while only a few involve larger frequency differences. Nevertheless, in a non-laboratory uncontrolled environment such as a field measurement, it is commonly unfeasible to guarantee a small frequency difference imposing further study on frequency recovery methods under larger frequency difference. Spurred by that, in this paper we propose a universal frequency recovery algorithm relying on the Remainder Matching (RM) technique, which is suitable for both large and small frequency differences. In our method, we employ the RM technique to determine the exact remainder combination in the first repetition frequency intervals and calculate the measured frequency. We also present the theoretical basis of RM, along with a summary of the system design rules, which have a significant impact on the performance of the measurement system. Finally, we challenge our RM-based solution on noise and analyze the corresponding false alarm rate metric. Our results demo nstrate that the proposed RM-based frequency recovery algorithm attains an appealing performance. [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]

As an electrical engineer, I like to view everything, large or small, in terms of an equivalent circuit of resistors, capacitors, inductors, and other components. To help me understand cell biology, I attempted to put together a simple equivalent circuit for a cell and validate it by electrical measurements. I soon found sympathy with far-sighted physical scientists and engineers from a century ago whose knowledge of biology was as poor as mine is now?not because they were too lazy to learn but because, back then, the knowledge did not exist. They made me sweat because, despite working with a suspension (mixture) of millions of cells, they gained insight into a single cell with the help of Maxwell [1] and Wagner [2]. [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]

In this study, electric field strength ($E$) levels of high-voltage lines were measured monthly in Sütlüce (38°N, 41°E), Muş, Turkey, between 2014 and 2018, and the obtained 60 monthly mean values were used as time series (TS) to forecast next 12 months by using conventional statistical and deep learning (DL) algorithms. In addition to the conventional statistical and DL algorithms developed for R, advanced algorithms, such as long short-term memory (LSTM) and recurrent neural network (RNN) derivative, were also used in the prediction process. We applied a cross-validation technique to the electromagnetic field (EMF) data set obtained in a period of 60 months. Thus, multiple algorithm performances were compared for the same data set. In addition, the electrical field values measured in the Sütlüce neighborhood were found to exceed the International Commission on Non-Ionizing Radiation Protection (ICNIRP) values. [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]

We propose a new contactless phase comparison method for high-voltage overhead lines. Combined with single-axis electric field (EF) sensing technologies, the new phase comparison method can perform a remote field measurement before the measured two overhead lines are interconnected. In the new phase comparison method, two single-axis EF sensor arrays are placed below the two measured overhead lines individually. A synchronous driver system wirelessly triggers the two EF sensor arrays synchronously to measure space electric fields. Then, two sets of measured electric fields are received by the synchronous driver system, and these data are used to carry out 1) positive/negative sequence evaluation and 2) phase evaluation. Finally, the proposed method can determine whether the three-phase voltage phases of the two overhead lines are identical. In addition, in order to ensure that the EF sensor arrays can synchronously measure electric fields, each EF sensor is designed with a built-in GPS device. Firstly, we simulated the electric field distribution of overhead lines using a finite element analysis (FEA) software, and then designed the placement of EF sensors on the ground. Finally, we validated the proposed method by experimental tests on a reduced scale model of overhead lines. [ABSTRACT FROM AUTHOR]

In this letter, imaging of moving targets with qualitative microwave imaging methods (Q-MWMs) is addressed. The problematic side of Q-MWM is the requirement of background measurement. To eliminate this necessity, the total electric field measured at different time instants (say $E^{\mathrm{ tot}}_{n}$ and $E^{\mathrm{ tot}}_{l}$ are the total electric fields measured at the $n$ th and $l$ th time instants, respectively) is applied to Q-MWM. For these input data, the output of Q-MWM can be assumed to be the summation of the indicators at these time instants (i.e., $E^{\mathrm{ tot}}_{n}-E^{\mathrm{ tot}}_{l}$ produces the differential indicator $I_{nl}=I_{n}+I_{l}$ , where $I_{n}$ and $I_{l}$ are the indicators at the $n$ th and $l$ th time instants, respectively). Using this information for all possible time pairs, an equation system is set for indicator values at different time instants. Solving this equation system, the indicator of Q-MWM for each measurement time is obtained, without taking any background measurement. The performance of the proposed algorithm is verified for the linear sampling method (LSM), which is an example of Q-MWM, with the 3-D and 2-D [both transverse magnetic (TM) and transverse electric (TE)] experimental measurements performed in a nonanechoic environment. [ABSTRACT FROM AUTHOR]

The access impedance of low-voltage (LV) power networks is a major factor related to the performance of the narrow-band power line communications (NB-PLCs) and, in a wider sense, to electromagnetic compatibility (EMC) performance. Up to date, there is still a lack of knowledge about the frequency-dependent access impedance for frequencies above 9 kHz and up to 500 kHz, which is the band where the NB-PLC operates. The access impedance affects the transmission of the NB-PLC signal, and it determines the propagation of the non-intentional emissions that may disturb other electrical devices, including malfunctioning or reduced lifetime of equipment. This paper presents the results of field measurements of the LV access impedance up to 500 kHz in different scenarios, with measurement locations close to end users and near transformers. The results provide useful information to analyze the characteristics of the LV access impedance, including variation with frequency, ranges of values for different frequency bands, and analysis of specific phenomena. Moreover, the results reveal a diverse frequency-dependent behavior of the access impedance in different scenarios, depending on the grid topology, the number of end users (that is, number and type of connected loads), and the type of transformation center. Overall, the results of this paper offer a better understanding of the transmission of NB-PLC signals and EMC-related phenomena.

Electric-field (EF) microsensors with high resolution are crucial for the realization of real-time dynamic status monitoring of Ubiquitous Power Internet of Things (UPIoT), which is of great significance for the safe operation of power system and early-stage diagnostics of power equipment. Distortion-free and high-resolution measurement of electric fields is also important in applications such as meteorological monitoring and aerospace launch. Existing electric-field measurement methods are always costly, bulky, and low in resolution. We presented a capacitive EF sensor with small size and high resolution. The presented sensor is based on piezoelectric effect, and a micro cantilever structure is realized using microfabrication. Simulation and experimental results indicate that the presented sensor has a resolution of about 45 V/m and a measurable magnitude of over 1.5 MV/m. Owing to the characteristics of small size, low cost and low power consumption, the EF sensor is suitable for applications of large-scale sensing arrays. [ABSTRACT FROM AUTHOR]

We experimentally investigate the influence of non-linear electrolytic screening by the electric double layer (EDL) and its impact on the field-effect transistor (FET) sensitivity to charged (bio)molecules. We use DNA hybridization to a PNA capture probe layer as model system. By co-depositing positively or negatively charged blocker molecules together with the PNA capture probes on the negatively charged SiO2 surface of the FET, we control the overall surface charge and modulate the strength of local ion concentration within the EDL. We observe a FET signal enhancement of up to 51% when the overall charge including the captured analyte itself swings roughly symmetrically around zero during capture, as confirmed by zeta potential measurements. Surface plasmon resonance measurements rule out a change in captured analyte density as the origin of the enhancement in sensitivity. This confirms that excess screening caused by the large local ion concentration, which increases non-linearly with potential in the EDL, is responsible for a loss in sensitivity in bioFETs with a charged surface. These experimental findings agree with the early theoretical works that find a low surface potential to be desirable for the best bioFET performance. [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]