Hasil untuk "Electric apparatus and materials. Electric circuits. Electric networks"

Sina Zare Pakzad, Patrick Egger, Negin Rahnemai Haghighi et al.

ABSTRACT This study presents a comprehensive investigation into the noise behavior of piezoelectric MEMS devices using a combined experimental and modeling‐based approach. A detailed analysis is performed to decompose the total noise into its constituent sources, including thermal noise in the piezoelectric layer, input voltage noise of the amplifier, input current noise of the amplifier, and the thermal noise of the bias resistor within the amplifier. Noise spectral density measurements are carried out from a few Hz to 1 MHz. They exhibit a pronounced 1/f characteristic at lower frequencies, where amplifier‐related noise sources are significant. The proposed electrical noise modeling framework accurately reproduces the experimental data, validating its effectiveness in capturing noise contributions across the operating bandwidth. Additionally, temperature‐dependent measurements reveal reductions in both capacitance (3%) and loss tangent (75%) of the aluminum nitride piezoelectric layer when cooled from 300 to 80 K, correlating with a corresponding decrease in the device's thermal noise. These results provide valuable insights into the optimization of piezoelectric MEMS devices for low‐noise applications, particularly in cryogenic environments, and contribute to advancing the design of next‐generation high‐sensitivity MEMS/NEMS sensors and actuators.

Minhao Zhang, Jinquan Zeng, Yiying Chen et al.

This review focuses on recent progress in optimizing the energy storage performance of dielectric ceramic and indicates the correlation between performance and the designed microstructure. Principles and key parameters of dielectric energy storage are described, and optimized strategies on microstructure with improving energy storage performance are briefly collected, named domain engineering, grain refining strategy, textured ceramic design, multi-phase engineering, core-shell structure design, and multilayer structural design. Conclusion with existing challenges and perspectives of microstructure control on optimizing energy storage performance dielectric ceramic are finally presented.

Liron Cohen, Emmanuel Bender

Schmitt Triggers are essential building blocks in noise-resilient systems and are useful in managing switching behavior in low-power designs. Yet, as CMOS technologies scale down, their designs become increasingly challenging. This paper presents a comprehensive investigation into the performance and reliability of multiple Schmitt Trigger topologies across two CMOS technology nodes (180 nm and 45 nm), with a particular focus on transistor sizing and layout optimization through multi-finger transistor structures. A series of pre-layout and post-layout simulations reveal that fingered implementations significantly enhance hysteresis robustness, switching speed, and delay consistency in PVT variations. Notably, post-layout results in 45 nm technology demonstrate remarkable improvements in both speed and power efficiency. This highlights the inadequacy of schematic-level models to predict the true behavior of fingered transistor configurations. Additionally, we explored the implications of finger designs on reliability concerns including electromigration and IR drop to determine the tradeoff between interconnect reliability optimization and internal routing. The findings establish practical design guidelines for optimizing number of fingers based on device width and technology node, offering new insights into layout-aware Schmitt Trigger design for high-performance and area-constrained applications.

Temitayo O. Olowu, Milad Behnamfar, Olusola T. Odeyomi et al.

FEA-based design optimization of high frequency transformers (HTSs) are by far more accurate but they come at huge computational cost. This paper presents a Gaussian Process Regression-based multiobjective design optimization technique for HFTs. The GPR model is formulated mathematically and trained using extensive FEA-based multiphysics simulations to predict three optimization objectives which include the HFT’s power loss, cost and power density. The GPR model is coupled with a Non-dominated Sorting Genetic Algorithm multiobjective optimization algorithm to determine the Pareto Optimal Solutions (POS). The optimization variables are the geometrical parameters of the HFT core and are constrained based on practical amorphous cores designs. The HFT is integrated into dual active bridge DC–DC resonant converter. The GPR-based multi-objective optimization results are compared with those obtained more accurate FEA-based solutions. The results obtained are validated experimentally. The results show that the proposed GPR-based HFT design optimization is a very promising framework in determining the optimal design parameters of the HFTs with acceptable level of accuracy.

Hanyoung Lee, Ardianto Satriawan, Hanho Lee

Fully Homomorphic Encryption (FHE) allows computational processing of encrypted data on cloud servers, providing high security and enabling safe data utilization. As homomorphic multiplication progresses with encrypted data, noise accumulates, requiring a process called bootstrapping to restore the noise level of the new ciphertext <inline-formula> <tex-math notation="LaTeX">$ct^{\prime }$ </tex-math></inline-formula>. Bootstrapping involves linear transformation processes, such as Coefficient to Slots and Slots to Coefficient, where most operations used are rotation. Rotation shifts elements in slots to new positions based on rotation index k. However, the computational cost and memory bandwidth required for a rotation adds significant overhead and limits the ability to perform FHE operations. Therefore, an efficient implementation of rotation is crucial for high-performance FHE applications. To address this problem, we optimized the datapath of rotation in the CKKS scheme to be hardware-friendly and proposed a homomorphic evaluation cluster hardware accelerator tailored for FHE workloads. Our architecture is aware of the computational and memory constraints of field programmable gate arrays (FPGAs) and performs number theoretic transform (NTT), its inverse (INTT), key multiplication, base conversion, and automorphism in a single cluster. We implemented our design in the AMD Alveo U280 FPGA platform. With a polynomial length of 216 and operating at 250 MHz as a rotation accelerator, the design implementation on the FPGA shows a speed-up of about <inline-formula> <tex-math notation="LaTeX">$700\times $ </tex-math></inline-formula> compared to the CPU implementation in OpenFHE. Compared to the GPU implementation, it shows a <inline-formula> <tex-math notation="LaTeX">$1.77\times $ </tex-math></inline-formula> speed-up, and compared to previous FPGA implementations, it shows a <inline-formula> <tex-math notation="LaTeX">$1.13\times $ </tex-math></inline-formula> better.

Jing Lang, Fujun Xu, Jiaming Wang et al.

Abstract AlGaN‐based ultraviolet light‐emitting diodes (UV‐LEDs) have the advantages of mercury (Hg) pollution free, small size, high efficiency, and so on, and are widely used in military, medical, and industrial fields, which are considered to be the most promising alternative to the traditional Hg lamps. Great efforts are made over the past few decades to improve the device performance, thereby meeting the commercial production and application requirements of UV‐LEDs, which is always accompanied by a series of interesting physical topics. In this review, the recent research progress in performance of AlGaN‐based UV‐LEDs is summarized from the perspectives of electrical injection, electro‐optical conversion, and light extraction, which are responsible for the operation of devices. The detailed discussions include the major challenges, the corresponding technological breakthroughs, and also the outlook of material growth, energy band modulation, as well as device fabrication involved in UV‐LEDs, which are expected to be helpful for the thorough comprehension of device physics and further development of AlGaN‐based UV‐LEDs.

Sebastien Fregonese, Thomas Zimmer

This work focuses on a novel methodology to establish on-wafer calibration standards for the 16-Term Error Calibration Technique. It combines TRL-calibrated data with EM simulation to precisely generate S-parameters of standards. Applied to the advanced BiCMOS 55 nm technology, with a layout maintaining consistent coupling between standards, the 16 error-terms calibration results in significant improvements from 40 GHz onward compared to standard calibration (SOLT or TRL) techniques. Notably, it corrects probe couplings, eliminates discontinuities between frequency bands, and ensures the accuracy of S-parameter measurements. Unlike traditional SOLT and TRL methods, this new approach attributes measured quantities solely to intrinsic transistor behavior.

Harvey Amorín, Michel Venet, José E. García et al.

Abstract Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) stands out among lead‐free ferroelectric oxides under consideration to replace state‐of‐the‐art high‐sensitivity piezoelectric Pb(Zr,Ti)O3, for a range of energy conversion ceramic technologies. However, the best performances have been reported for very coarse‐grained materials, and attempts to refine microstructure below 10 µm grain size consistently result in significant property degradation. Here a comprehensive study of the grain size effects on the properties of BCZT across the micron scale is reported, down to the verge of the submicron one. Results show a distinctive early evolution of properties for grain sizes between 1 and 5 µm. For the larger sizes in this range, an opposite effect is found for the piezoelectric charge coefficient and electric field‐induced strain with respect to the very coarse‐grained material, while very good overall performance is maintained. For the lower sizes, relaxor features appear, yet materials can still be poled indicating their ferroelectric nature. This strongly resembles size effects in the Pb(Mg1/3Nb2/3)O3‐PbTiO3 system, driven by the slowing down of the relaxor to ferroelectric transition with size reduction, though kinetics seem to slow down across much larger grain sizes for BCZT. Concomitant changes in the polymorphic phase coexistence are described and discussed by synchrotron X‐ray diffraction.

Adeline Guéret, Wolf-Peter Schill, Carlos Gaete-Morales

Electrifying the car fleet is a major strategy for mitigating emissions in the transport sector. As electrification cannot solve all negative externalities associated with cars, reducing the size of the car fleet would be beneficial. Electric carsharing could allow to reconcile current car usage habits with a smaller fleet, but this may reduce the potential of electric cars to align their grid interactions with variable renewable electricity generation. We investigate how electric carsharing may impact the power sector, combining three methods: sequence clustering of car travel diaries, generation of synthetic electric vehicle time series, and power sector modelling. We show that switching to electric carsharing only moderately increases power sector costs, less than 110 euros per substituted car in our main setting. This effect is largest with bidirectional charging. We conclude that the power sector interactions of shared electric car fleets could still be aligned with variable renewable electricity generation.

Daniel Garcia Aguilar, Logan DeHay, Jahn Aquino et al.

This paper examines the impact of electric vehicle (EV) charging stations on the capacity of distribution feeders and transformers within the electric grid at California State University Northridge (CSUN). With the increasing adoption of both residential and commercial EVs and the rapid expansion of EV charging infrastructure, it is critical to evaluate the potential overloading effects of intensive EV charging on power distribution systems. This research assesses the impact of EV charging on the operation of CSUN's electric grid, identifying potential overload risks under projected EV adoption scenarios. Detailed simulations and analyses are conducted to quantify the extent of these impacts, focusing on various levels of EV penetration and charging patterns. The study also explores the impact of distributed generation on reducing the stress incurred by EV loads. The findings provide essential insights for utility companies, highlighting the need for strategic upgrades to distribution systems. These insights will help in developing robust strategies for both current operations and future planning to accommodate growing EV charging demands, ensuring grid stability and reliability in the face of increasing electrification of the transportation sector. The modeled CSUN electric grid can be used as a benchmark to study the impact of EV loads in dense areas on various parameters of the grid.

Galyna Sych, Patrice Rannou, Maxime Jullien‐Palletier et al.

Abstract Organic electrochemical transistors (OECT) are gaining momentum in future applications of biosensors and bioelectronics. Nonetheless, contact (or series) resistances (RS/D) remain underexplored, even though physical processes between the source/drain electrodes and organic mixed ionic‐electron conductors (OMIECs) drive a substantial part of their performances. To address this shortcoming, in this study, low‐dimension OECTs featuring 2 µm‐long poly(3,4‐ethylenedioxythiophene) and polystyrene sulfonate acid (PEDOT:PSS) channel are explored. Normalized contact resistances (RS/D⋅W) values as low as 1.4 W cm are obtained. It is observed that channel PEDOT:PSS thickness is not detrimental to RS/D but is impacting the cut‐off frequency. A figure‐of‐merit (h) expressing the charge‐carrier injection (or extraction, respectively) efficiency shows that planar depletion‐mode OECTs are not contact‐limited up to L = 30 µm channel length. Finally, an unprecedented approach that highlight the importance of optimizing the micro‐fabrication technologies is shown, by decreasing the contact overlap length, according to OMIECs physicochemical contact properties. Indeed, a transfer‐length method coupled to a current‐crowding model allow to fully understand the behavior of low‐dimension PEDOT:PSS OECTs and next, to optimize its circuits design. This is paving the way toward the development of OECTs‐based integrated circuits with faster switching speed, broadening further their scopes and future use as advanced bioelectronics platforms.

S. Lalitha, M. Sundararajan

Internet of Things Networks (IOTN) are applied in all sectors as a result of their broad applicability. Even though the performance of IOTN is satisfactory, it still faces various obstacles, including energy constraints, dependability, and security. This work aims to improve the reliability of the network by identifying defective nodes. Defective nodes affect the normal functionality of the entire network; therefore, it is vital to detect the defective nodes, such that the Quality of Service (QoS) is improved. This work detects defective nodes by employing the Reward-and-Punishment Model (RPM) and the hypothetical analysis of Dempster-Shafer (DS) theory. The effectiveness of the proposed work is found to be satisfactory in terms of defective node detection, precision, energy consumption, and network lifetime.

Xing-Guo Ye, Huiying Liu, Peng-Fei Zhu et al.

Berry curvature dipole plays an important role in various nonlinear quantum phenomena. However, the maximum symmetry allowed for nonzero Berry curvature dipole in the transport plane is a single mirror line, which strongly limits its effects in materials. Here, via probing the nonlinear Hall effect, we demonstrate the generation of Berry curvature dipole by applied dc electric field in WTe2, which is used to break the symmetry constraint. A linear dependence between the dipole moment of Berry curvature and the dc electric field is observed. The polarization direction of the Berry curvature is controlled by the relative orientation of the electric field and crystal axis, which can be further reversed by changing the polarity of the dc field. Our Letter provides a route to generate and control Berry curvature dipole in broad material systems and to facilitate the development of nonlinear quantum devices.

Walter Schirmacher, Thomas Franosch, Marco Leonetti et al.

We consider Maxwell's equations in a 3-dimensional material, in which both, the electric permittivity, as well as the magnetic permeability, fluctuate in space. Differently from all previous treatments of the disordered electromagnetic problem, we transform Maxwell's equations and the electric and magnetic fields in such a way that the linear operator in the resulting secular equations is manifestly Hermitian, in order to deal with a proper eigenvalue problem. As an application of our general formalism, we use an appropriate version of the Coherent-Potential approximation (CPA) to calculate the photon density of states and scattering-mean-free path. Applying standard localization theory, we find that in the presence of both electric and magnetic disorder the spectral range of Anderson localization appears to be much larger than in the case of electric (or magnetic) disorder only. Our result could explain the absence of experimental evidence of 3D Anderson localization of light (all the existing experiments has been performed with electric disorder only) and pave the way towards a successful search of this, up to now, elusive phenomenon.

Shiva P. Poudel, Juan M. Marmolejo-Tejada, Joseph E. Roll et al.

Two-dimensional (2D) materials are being explored as a novel multiferroic platform. One of the most studied magnetoelectric multiferroic 2D materials are antiferromagnetically-coupled (AFM) CrI$_3$ bilayers. Neglecting magnetism, those bilayers possess a crystalline point of inversion, which is only removed by the antiparallel spin configuration among its two constituent monolayers. The resultant intrinsic electric dipole on those bilayers has a magnitude no larger than 0.04 pC/m, it points out-of-plane, and it reverts direction when the--Ising-like--cromium spins are flipped (toward opposite layers {\em versus} away from opposite layers). The combined presence of antiferromagnetism and a weak intrinsic electric dipole makes this material a two-dimensional magnetoelectric multiferroic. Here, we remove the crystalline center of inversion of the bilayer by a relative $60^{\circ}$ rotation of its constituent monolayers. This process {\em enhances} the out-of-plane intrinsic electric dipole tenfold with respect to its magnitude in the non-rotated AFM bilayer and also creates an even stronger and switchable in-plane intrinsic electric dipole. The ability to create a three-dimensional electric dipole is important, because it enhances the magnetoelectric coupling on this experimentally accessible 2D material, which is explicitly calculated here as well.

Russell H. Kenney, Jorge L. Salazar-Cerreno, Jay W. McDaniel

In this paper, an optimization procedure for synthesizing shaped beams with an arbitrary geometry phased array system with real-time capability is presented. The algorithm involves a combination of an arbitrary extension of the Woodward-Lawson synthesis procedure with the magnitude least-squares optimization method. This simple combination significantly reduces the optimization time, enabling real-time beam shaping in response to changing requirements on beam shape or evolving geometry in distributed arrays. The technique places no restrictions on element positioning in all three spatial dimensions and is demonstrated to accurately reproduce the desired beam shape in both angular dimensions. The algorithm is demonstrated for multiple beam cases with a large, randomly generated array in computational simulation. The applicability of the algorithm to practical phased array hardware is also demonstrated using full-wave electromagnetic simulations and measurements of a realized arbitrary phased array system using a near-field scanner in an anechoic chamber.

Shivam Tiwari, Deepak Arora, Vishal Nagar

Depending on its intensity, sleep disorders can affect a person's ability to function mentally, emotionally, and physically. These are medical abnormalities of the subject's sleep structure. Most prevalent ones are bruxism, sleep problems, depression, and narcolepsy. A greater chance of acquiring sleep issues in the elderly includes sleeplessness, irregular leg movements, problems with fast eye movement behaviour and breathing abnormalities. Therefore, an early stage therapy that might save a patient's life depends on a precise diagnosis and categorization. The much more sensitive as well as significant bio-signal is electroencephalographic (EEG) signal. It has the capacity to record sleep-sensitive brain activity. We used an available EEG database which had recordings divided into different types of sleep disturbances as well as a healthy control group. Popular sensor's EEG brain function has been examined. Ultimately, using patterns taken from EEG data, a categorization AI model was created. Extracted characteristics worked well as a biomarker for identifying sleep problems when combined with an AI classifier.

Gergely Endrődi, Gergely Markó

We investigate the response of a hot gas of quarks to external electric fields via leading-order perturbation theory. In particular, we discuss how equilibrium is maintained in the presence of the electric field and calculate the electric susceptibility, providing its high-temperature expansion for arbitrary quark mass. Furthermore, we point out that there is a mismatch between this, direct determination of the susceptibility at zero field and the weak-field expansion of the effective action at nonzero electric fields, as obtained using Schwinger's exact propagator. We discuss the origin of this mismatch and elaborate on the generalization of our results to full QCD in electric fields.

Naoum Karchev

In our desire to give a new suggestion for H-based superconductors experiments we present a theoretical framework for understanding the impact of an applied electric field on pressured hydride superconductors. We study a material at pressure $p$, when it possesses insulator-superconductor transition, at the respective superconducting critical temperature $T_{cr}$. The theory shows the applied electric field penetrates the material and forces the Cooper pairs to Bose condensate. If one applies an electric field and then increases the temperature, the theory predicts novel critical temperature $T^{el}_{cr}$ higher than $T_{cr}$. Therefore, the system has a higher superconducting critical temperature if we apply an electric field instead of increasing the pressure. The result shows that in the case of carbonaceous sulfur hydride at $234Gpa$ and near but below critical temperature $T_c=283K$, applying a sufficiently strong electric field, we can bring the superconducting critical temperature close to 300K.

Charalampos Avraam, Luis Ceferino, Yury Dvorkin

The growing frequencies of extreme weather events and cyberattacks give rise to a novel threat where a malicious cyber actor aims to disrupt stressed components of critical infrastructure systems immediately before, during, or shortly after an extreme weather event. In this paper, we initiate the study of Compound Cyber-Physical Threats and develop a two-stage framework for the analysis of operational disruptions in electric power networks and economy-wide impacts under three scenarios: a Heatwave, a Cyberattack, and a Compound scenario when the Cyberattack is timed with the Heatwave. In the first stage, we use a bilevel optimization problem to represent the adversarial rationale of a cyberattacker in the upper level. In the lower level, we model disruptions in the electric power network using an optimal power flow model. In the second stage, we couple the disruption of electricity supply with a Computable General Equilibrium model to elucidate the impacts on all economic sectors. For the New York Independent System Operator, we find that a 9% demand increase in a Heatwave may not lead to unserved load. The Cyberattack can lead to 4% of unserved electric load in Long Island, while the Compound scenario can increase unserved electric load in Long Island to 13% and affect almost 600,000 customers. Our results show that the activity of state and local government enterprises can decrease by 30% in the Compound scenario. We conclude that the vulnerability of federal, state, and local government enterprises to electricity disruptions can affect a broad range of populations.