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

Suwon Seong, Taejun Ha, Sangwook Jung et al.

ABSTRACT The increasing complexity of artificial intelligence has exposed critical limitations of conventional von Neumann architectures, particularly in terms of data transfer bottlenecks and high energy consumption. Consequently, alternative paradigms such as in‐memory and neuromorphic computing have attracted significant attention. Oxide semiconductors, which have achieved commercial success in the display industry, have recently garnered significant attention for neuromorphic computing applications due to their unique properties, including extremely low leakage current, low processing temperatures, and excellent compatibility with back‐end‐of‐line integration with conventional silicon circuits. This review discusses recent advancements and challenges in oxide semiconductor‐based devices for in‐memory and neuromorphic computing. It explicitly addresses multilevel memory devices optimized for analog multiply‐accumulate operations, highlighting key trade‐offs among retention, endurance, operational speed, and energy efficiency. Neuromorphic synaptic devices utilizing oxide semiconductors are highlighted for their effective emulation of synaptic behaviors for spiking neural networks. Additionally, recent developments in optoelectronic neuromorphic systems and reservoir computing using oxide semiconductors are presented, along with insights into emerging device structures and future opportunities for 3D integration to maximize computing efficiency.

Duc Anh Lai, Devin A. Matthews

Electric field-assisted chemistry has attracted much attention in recent years, particularly in the context of oriented external electric fields for controlling molecular structure and reactivity. Such fields have been explored in a wide range of applications, including switching materials, nanoparticles, controllable catalysts, medicines, and clinical therapies. However, the use of fixed fields in the laboratory frame becomes ineffective for flexible molecules, as conformational changes can significantly alter their orientations. In this work, we propose two molecular reference frames -- the principal axis frame and the local reference frame -- to define oriented electric fields within the molecular framework. These coordinate systems powerfully eliminate ambiguities in the relative orientation between the applied field and the molecule. Analytic nuclear gradients in the presence of external electric fields are derived and implemented, with an initial application to field-dependent geometry optimizations of cis- and trans-formanilide. Analysis of the resulting field-induced equilibrium structures reveals distinct structural responses, validating the accuracy and robustness of the proposed formalism. The analytic gradient framework enables systematic investigations of molecular properties and reactivity under arbitrarily oriented electric fields, opening new opportunities for computational modeling and rational design in electric field-controlled chemistry.

Yuxuan Xu, Haibin Zhou, Qi Chen et al.

With the continuous increase in operating speed of high-speed trains, enhanced safety and stability in braking systems are necessitated. Copper-based friction materials (CBFMs) are predominantly utilized in brake pads for high-speed trains exceeding 300 ​km/h. Substantial braking energy is dissipated by CBFMs through direct interaction with counterpart materials, and their pivotal role in maintaining the safety and reliability of high-speed braking systems is ensured. The components and intrinsic properties, the multiple variations at the interface, and the distinctive characteristics of brake conditions are regarded as the primary factors influencing the braking properties of CBFMs. Recent advancements in CBFMs and tribological properties are systematically explored in this review from three critical perspectives: components, interfaces, and tribo-layers. Firstly, the emerging trends in matrix, lubricant components, and abrasive components in CBFMs are detailed. Secondly, the correlation between interfacial and tribological properties at both micro and macro scales is investigated. Thirdly, the characteristics of tribo-layers at different scales and the associated wear mechanisms of CBFMs are examined. Lastly, the challenges CBFMs face and the constraints of multi-component synergistic design, evaluation methodologies, and novel wear mechanisms are highlighted.

Enrique M. Spinelli, Valentín A. Catacora, Federico N. Guerrero et al.

Fully differential amplifier circuits are well suited for instrumentation front ends and signal-conditioning applications. They offer high common-mode rejection ratios (CMRRs) regardless of the passive component tolerances but remain sensitive to imbalances in active devices. By using power supply bootstrapping (PSB), the CMRRs of these circuits can be improved, where they become independent of mismatches in both passive and active components. This technique works by forcing the power supply nodes to follow the common-mode input voltage, which significantly enhances the CMRR. However, this approach introduces stability issues that must be addressed through dedicated compensation strategies without degrading the overall performance. In this work, the theoretical background, a design methodology, and experimental validation are presented. The proposed technique was applied to a fully differential amplifier built with general purpose operational amplifiers. Prior to the PSB, the amplifier exhibited a CMRR of 90 dB at 1 kHz. A straightforward application of PSB led to instability in the common-mode behavior; however, with the proposed compensation method, the amplifier achieved stable operation and an improved CMRR of 130 dB.

Fu‐Gow Tarntair, Chih‐Yang Huang, Siddharth Rana et al.

Abstract In this study, in situ, Si‐doped heteroepitaxial Ga2O3 layers are grown on c‐plane sapphire by metalorganic chemical vapor deposition. The X‐ray diffraction peaks of the doped Ga2O3 epilayers shows ß‐phase of Ga2O3 ,and full width at half maximum of Ga2O3 crystallinity is decreased at a Tetraethoxysilane (TEOS) molar flow rate of 2.23 × 10−7 mol min−1 but increased with higher flow rates. The dopant concentrations of Ga2O3 grown at 825 °C with TEOS molar flows of 2.23 × 10−7, 4.47 × 10−7, and 6.69 × 10−7 mol min−1 are measured to be 5.5 × 1019, 1.1 × 1020, and 1.4 × 1020 atom cm−3, respectively, using secondary ion mass spectra and Hall measurements reveal n‐type nature with carrier concentrations of 6.5 × 1017, 3.2 × 1018, and 3.9 × 1018 atom/cm3 , respectively. To increase Si dopant activation, Ga2O3 growth temperature is raised to 875 °C. The result suggests a higher growth temperature can contribute to a greater probability of Si substitution on Ga lattice sites, which further reduces the resistivity of Ga2O3 epilayer. Moreover, results are compared with theoretical Density Functional Theory  studies.

Yanzhuo Wei, Guohui Li, Hongwei Hao et al.

Abstract Extending the visible light response of indium gallium zinc oxide (IGZO) phototransistors is crucial for advanced optical neuromorphic computing and artificial visual perception systems. Using water (H2O) as the oxidant during atomic layer deposition of aluminum oxide (Al2O3) interlayer introduces hydroxyl impurities within IGZO, generating subgap defects that boost photo‐sensitivity (≥106) and photo‐responsivity (≥0.1 A W−1) under 420–620 nm visible light stimuli. The resultant IGZO/Al2O3(H2O) synaptic transistor successfully emulates visible‐light‐driven plasticity. In comparison, the Al2O3 using ozone (O3) as the oxidant is found to produce lesser defects within IGZO but creates a decent amount of negative fixed charges at the interface, improving the contact properties between IGZO and source/drain electrodes. Through innovative experimental design and in‐depth surface analysis, this work offers new insights into the microscopic origin responsible for subgap absorption and contact properties in IGZO/Al2O3 structure, serving as guidelines toward designing scalable synaptic devices with enhanced optoelectronic properties.

Shenggao Li, Tony Chan Carusone

Huachang Guo, Jun He, Jie Sun et al.

Abstract Micro light‐emitting diodes (Micro‐LEDs) are regarded as the core of next‐generation display technology due to their high brightness and energy efficiency. However, the reduction in the size of Micro‐LEDs has led to increased manufacturing challenges and exacerbated issues such as sidewall emission, which hinder the development of high‐pixel‐density displays. This paper proposes a vertically stacked Micro‐LED design based on an L‐shaped metal wall structure, aiming to suppress sidewall emission and enhance top light extraction efficiency (LEE). Through parameter scanning, the dimensions of the Micro‐LED and the thickness of the epitaxial layer are optimized. Combined with inclined sidewalls and the reflective structure of the L‐shaped metal wall, the optical characteristics of red, green, and blue Micro‐LEDs are analyzed using ray‐tracing simulations. The sidewall emission is significantly reduced (with a maximum reduction of 68.04% compared to vertically stacked Micro‐LEDs without metal walls), and top light emission is enhanced (the LEE within ±90° direction for blue, green, and red light increased by 196.18%, 51.69%, and 3.45%, respectively, compared to stacked Micro‐LEDs without metal walls). The simulation results demonstrate the potential of the L‐shaped metal wall in vertically stacked full‐color Micro‐LED displays, providing a new approach to suppressing optical crosstalk and improving display performance.

Xinyi Song, Xiaohui Wang, Wei Liu et al.

Abstract Due to the advantages of multiplicity, functionality, and flexibility of organic building blocks, organic piezoelectric materials are regarded as next‐generation materials for potential applications in flexible sensors and energy harvesting devices. Here, a new pure organic pyrene‐based molecule, PyPT is presented, which crystallizes in a non‐centrosymmetric structure. PyPT is synthesized and demonstrated to be suitable for developing flexible sensors due to its remarkable piezoelectric properties. The pyrene‐based piezoelectric molecule exhibits excitation wavelength‐dependent emission behavior and aggregation‐caused quenching properties and demonstrated a piezoelectric coefficient (d33) of 8.02 ± 0.26 pm V−1. The output electronic signal of a PyPT‐based flexible sensor shows a significant increase from 30 to 721 pA as the strain increases from 0.12% to 0.59% with a low Young's modulus of 1.63 Gpa. This high‐performance piezoelectric sensor can serve as a sensitive sound sensor for sound detection and recognition based on the basic characteristics of sound, such as amplitude, frequencies, and timbres. This research offers new insights into advancing pure organic luminescent materials with piezoelectric properties, paving the way for applications in flexible electronics for wearables, human–machine interfaces, and the Internet of Things.

M. J. Grzybowski, W. Pacuski, J. Suffczyński

Altermagnetic materials have attracted a lot of attention recently due to the numerous effects, which have an application potential and occur due to the spin-split band structure coexisting with the compensated magnetic order. Incorporation of such intriguing compounds into low-dimensional structures represents an important avenue towards exploiting and enhancing their functionalities. Prominent examples of this group are semiconductors well suited to the band-gap engineering strategies. Here, we present for the first time visible-light-emitting CdSe quantum wells, in which wurtzite MnSe as an alermagnetic candidate plays the role of a barrier. Photoluminescence experiments with temporal resolution demonstrate that in such quantum wells, a built-in electric field is present and strongly influences the energies of the emitted photons, the dynamics of recombination, and excitation power dependence. Numerical simulations allow us to estimate that the magnitude of the electric field is 14MV/m. We anticipate that such quantum wells offer potential to probe the barrier properties and that wurtzite MnSe is an interesting platform to study the interplay of the altermagnetism and built-in electric field.

Alexander Petrov, Leonid Skripnikov

The g-factors for $J = 1$, $F=3/2$, $|M_F|=3/2$ hyperfine levels of the ground electronic state $^3Δ_1$ of the $^{232}$ThF$^+$ cation are calculated as functions of the external electric field. These calculations are necessary for the analysis of systematic effects in the experiment aimed at searching for the electron electric dipole moment.

Ankit Srivastava, Munesh Chandra, Ashim Saha

Prostate cancer, or PCa, is a prominent male malignancy. For men with prostate cancer, accurate staging is essential for planning treatment and determining the prognosis. The way prostate cancer is currently diagnosed has led to two types of problems: overdiagnosis, which results in overtreatment, and underdiagnosis, which leads to missed diagnoses. Multiparametric magnetic resonance imaging (mpMRI) could assist in reducing prostate cancer diagnosis errors. Automatic prostate cancer techniques often use deep learning or machine learning to identify the lesion or tumor. Even after using these methods, they are not accurate every time in detecting and identifying prostate tumors after giving multiple sequences of mpMRI as input. Due to the absence of a clinically established test dataset, the output of the automatic prostate cancer system is extremely hard to verify. With the help of Explainable Artificial Intelligence (XAI) and expert review, the results of automatic prostate cancer techniques can be verified.

Daeyoung Chu, Donghwan Han, Sanghyun Kang et al.

Abstract Advanced filamentary devices are crucial for developing low‐power devices to implement high‐speed logic and neuromorphic devices. Among these, HfO2‐based filamentary devices have attracted attention as viable options due to their threshold‐switching characteristics and compatibility with complementary metal‐oxide‐semiconductor (CMOS) technology. However, the unpredictability of conventional filament formation/rupture driven by an electric field challenges consistency and reliability. A paradigm shift from conventional stochastic electric field‐driven ion migration to controllable ion‐based transportation is essential to devise functional low‐power devices capable of controlling the filament process. This work introduces a magnetic field‐assisted threshold switching (MA‐TS) device, which integrates a neodymium magnet and a nickel (Ni) barrier layer to enable controlled dual field‐driven ion transportation. The dual field‐driven process combining the conventional vertical electric field‐driven ion migration with lateral magnetic field‐driven ion transportation, reveals a distinctive aspect of ion movement. The MA‐TS device achieves superior performances characterized by an ultra‐low threshold voltage (≈0 V), minimized leakage current in the off‐state, a variation‐immune hysteresis‐free characteristic, enhanced yield, and revival‐ability (i.e., self‐healing) after a failed TS operation. By overcoming the limitations of conventional filamentary devices, the MA‐TS device opens up a promising avenue for efficient and stable low‐power applications.

Nian Liu, Huifang Ma, Maorui Li et al.

Abstract Electroconductive hydrogels (ECHs) have been extensively explored as promising flexible materials for bioelectronics because of their tunable conductivity and tissue‐like biological and mechanical properties. ECHs can interact intimately with biosystems, transmit physiological signals, and are expected to revolutionize the convergence between organisms and electronics. However, there are still some challenges in utilizing ECHs as flexible materials for bioelectronics, such as mismatched stretchability with tissues, a lack of environmental adaptability, susceptibility to mechanical damage, inferior interface compatibility, and vulnerability to bacterial contamination. This review categorizes these challenges encountered in the bioelectronic applications of ECHs and elaborates on the strategies and theories for improving their performance. Furthermore, we present an overview of the recent advancements in ECHs for bioelectronic applications, specifically focusing on their contributions to healthcare monitoring, treatment of diseases, and human–machine interfaces. The scope of future research on ECHs in bioelectronics is also proposed. Overall, this review offers a comprehensive exposition of difficult issues and potential opportunities for ECHs in bioelectronics, offering valuable insights for the design and fabrication of ECH‐based bioelectronic devices.

Kamal K. Samanta

Nuclear fusion on earth is a highly complex and challenging multidisciplinary field that aims to solve the global energy puzzle by providing infinite energy with zero carbon emissions. Achieving controlled thermonuclear fusion requires high-power RF and microwave circuits and systems covering a broad frequency range from MHz to sub-THz to reach critical plasma temperature and current density parameters. These systems differ from conventional RF systems and are massive (length/weight: kms/tonnes), deliver high CW power, and must operate in harsh environments such as ultra-high vacuum (UHV), high thermal and radiation stresses, and plasma disruption forces. This paper discusses the essential requirements and importance of various radio frequencies in fusion reactors, such as ion cyclotron, electron cyclotron, and hybrid resonances. It overviews high-power CW (100 s kW to MWs) amplifiers/sources, circuits, and complete systems incorporating antenna arrays and covering MHz to 100 s of GHz with examples of the SST-1 and ITER tokamaks from a microwave engineering perspective. The paper also highlights material selection, design, fabrication, and implementation challenges and techniques for high-power amplifiers and systems. The subsystems incorporate large coaxial, rectangular, and circular corrugated waveguide lines and components with fluid cooling, gas pressurization and UHV compatibility. They launch TEM, TE10, and HE11 modes to rapidly fluctuating plasma loads through various antenna modules with real-time matching, positioning, and beam steering capabilities. The paper concludes by discussing the RF system requirements, status, schedule, and key technical challenges of ITER, the world's largest and most ambitious nuclear fusion-based reactor project.

Yu. T. Tsap, A. V. Stepanov, Yu. G. Kopylova

We analyse electron acceleration by a large-scale electric field $E$ in a collisional hydrogen plasma under the solar flare coronal conditions based on approaches proposed by Dreicer and Spitzer for the dynamic friction force of electrons. The Dreicer electric field $E_{Dr}$ is determined as a critical electric field at which the entire electron population runs away. Two regimes of strong ($E \lesssim E_{Dr}$) and weak ($E \ll E_{Dr}$) electric field are discussed. It is shown that the commonly used formal definition of the Dreicer field leads to an overestimation of its value by about five times. The critical velocity at which the electrons of the ``tail'' of the Maxwell distribution become runaway under the action of the sub-Dreiser electric fields turns out to be underestimated by $\sqrt{3}$ times in some works because the Coulomb collisions between runaway and thermal electrons are not taken into account. The electron acceleration by sub-Dreicer electric fields generated in the solar corona faces difficulties.

Jinpeng Yuan, Wenguang Yang, Mingyong Jing et al.

Microwave electric field sensing is of importance for a wide range of applications in areas of remote sensing, radar astronomy and communications. Over the past decade, Rydberg atoms, owing to their exaggerated response to microwave electric fields, plentiful optional energy levels and integratable preparation methods, have been used in ultra-sensitive, wide broadband, traceable, stealthy microwave electric field sensing. This review first introduces the basic concept of quantum sensing, properties of Rydberg atoms and principles of quantum sensing of microwave electric fields with Rydberg atoms. Then an overview of this very active research direction is gradually expanded, covering progresses of sensitivity and bandwidth in Rydberg atoms based icrowavesensing,uperheterodyne quantum sensing with microwave-dressed Rydberg atoms, quantum-enhanced sensing of microwave electric field, recent advanced quantum measurement systems and approaches to further improve the performance of microwave electric field sensing. Finally, a brief outlook on future development directions is discussed.

G. Vasumathi, V. Jayalakshmi, K. Sakthivel

Today's power generation relies heavily on renewable energy, which also contributes to distributed generation, microgrids and smart cities. PV system is a rapidly developing source of renewable energy and acts as stand-alone or grid-connected systems. The utilization of PV energy faces a drastic increase due to the high efficiency of solar cells and enhancements in the design of PV panels. It demands high gain converters for major applications but existing converters generate pulsating outputs leading to output voltage with ripples. In this view, researchers are constantly focusing on converters with increased efficiency and gain generating minimized ripples in resulting current and voltage. Considering these dilemmas, an efficient PV system with KY integrated SEPIC converter is introduced in this article. The KY converter provides improved voltage conversion ratio as well as minimizes the voltage stress while the SEPIC converter offers added step up gain. The proposed converter is regulated by a GWO tuned PI controller for solving the optimization issues. It prevents the local optimum and is robust, simple with the application to complicated optimization tasks. A grid connected 1φ VSI is adopted for ensuring smooth operation with the aid of PWM generator. The simulations are carried out in MATLAB simulation software to prove the efficacy of the introduced approach. The obtained outputs reveal that this developed system has minimal THD value of 1.6% and hence it has higher efficiency which is marked as 97%.

M. Suguna, S. Sathiyabama

Wireless Sensor Network (WSN) comprises many small sensors nodes incorporated by IoT which plays vital role in several applications. IoT incorporates physical devices into a network structure that includes software, sensors to collect data from the surrounding environment, and sinks for data transmission. To increase network lifespan during data transmission, a resource-efficient routing system is needed. Different academics have been working on improving routing techniques recently to increase effectiveness and route discovery. The key issue affecting the performance of WSNs is an efficient resource usage of routing. In order to overcome this problem, a new technique called Hierarchical Point wise Mutual Informative Clustering-based Shift Invariant Deep Convolutive Neural Learning (HPMIC-SIDCNL) technique is introduced in WSN. The HPMIC-SIDCNL technique uses the Shift Invariant Convolutive Deep neural learning concept to learn the given input with help of several layers such as input, three hidden layers, and output layer. Initially, the IoT devices are used in sensor nodes for sensing and collecting patient data. In the input layer, sensor nodes are considered as input. Then input is transmitted into first hidden layer where resource of the sensor nodes such as energy and bandwidth are measured. Then estimated resources are transmitted into second hidden layer where the clustering process is carried out using the Hierarchical IBM Point wise Mutual Informative Clustering technique. The Hierarchical IBM clustering uses the Point wise Mutual Information for collection of sensor nodes depend on energy and bandwidth. In the third hidden layer, the cluster is selected on higher residual energy and minimum bandwidth for improving the data transmission and reduces the delay. The cluster head receives the patient data after it has been sent by the source node in that particular cluster. In order to perform data transmission from source to sink node at output layer, cluster then locates the closest cluster head. In this manner, cluster heads are used to execute resource-efficient healthcare data transmission from source to sink node, minimizing the latency. The obtained findings show that the suggested HPMIC-SIDCNL technique outperforms in terms of high delivery ratio with little packet loss and delay. The advantage of the proposed HPMIC-SIDCNL technique, it is simple to understand because it represents a solution to a given problem step by step and is not dependent on any programming language. Since everyone can understand it, even those without programming experience, it is simple.

Jian Zhang, Oliver Braun, Gabriela Borin Barin et al.

Abstract Atomically precise graphene nanoribbons (GNRs) are increasingly attracting interest due to their largely modifiable electronic properties, which can be tailored by controlling their width and edge structure during chemical synthesis. In recent years, the exploitation of GNR properties for electronic devices has focused on GNR integration into field‐effect‐transistor (FET) geometries. However, such FET devices have limited electrostatic tunability due to the presence of a single gate. Here, on the device integration of 9‐atom wide armchair graphene nanoribbons (9‐AGNRs) into a multi‐gate FET geometry, consisting of an ultra‐narrow finger gate and two side gates is reported. High‐resolution electron‐beam lithography (EBL) is used for defining finger gates as narrow as 12 nm and combine them with graphene electrodes for contacting the GNRs. Low‐temperature transport spectroscopy measurements reveal quantum dot (QD) behavior with rich Coulomb diamond patterns, suggesting that the GNRs form QDs that are connected both in series and in parallel. Moreover, it is shown that the additional gates enable differential tuning of the QDs in the nanojunction, providing the first step toward multi‐gate control of GNR‐based multi‐dot systems.