Switching Devices Research Articles

Impact of passivation on GaS nanoflakes: A study on stability, electronic, spectroscopy, and photocatalytic properties

This study uses first-principle calculations to investigate the properties of pristine and passivated gallium sulfide nanoflakes. Passivation significantly enhances stability, with fluorinated nanoflakes being the most stable and pristine nanoflakes the least stable, having formation energies of −0.058 eV/atom and −0.009 eV/atom, respectively. The pristine and passivated nanoflakes show semiconducting band gap, which lies in a visible region. Hydrogenated nanoflakes exhibit the largest band gap of 3.62 eV, making them highly suitable for photocatalysis, while fluorine and chlorine passivation result in band gaps of 3.16 eV and 3.01 eV. Scanning tunneling microscopy reveals distinct topographical features for each passivated nanoflake, affecting their electronic properties, including negative differential conductance, making it suitable for advanced switching devices and sensors. The quantum capacitance value of 815 µF/cm2 for chlorinated nanoflakes suggests that passivated nanoflakes could be beneficial for supercapacitor applications. Spectroscopic studies show that passivation changes the infrared spectrum and moves absorption spectra from the ultraviolet to the visible range. The hydrogenated nanoflakes are found ideal for water splitting, and adjusting the pH can further optimize its photocatalytic performance. These findings highlight the potential of passivated nanoflakes in photovoltaics, biomedical imaging, photocatalysis, and advanced technological devices.

Analysis of SF6 and CF4 consumption for refueling high-voltage switching equipment

The article describes to eliminate possible errors in the supply of cylinders with sulfur hexafluoride and cylinders with carbon tetrafluoride to high-voltage substations for refueling switching devices such as high-voltage switches, voltage transformers, etc. Conduct an analysis of possible erroneous supplies of the two above-mentioned gases at the substation. Make an analysis of possible residuals (or shortfalls) of gas cylinders after refilling. Make an assumption about the reasons for the appearance of possible residues. Give recommendations for overcoming possible problems. Make the appropriate calculations. Propose a formula (table) for recalculating the consumption of both types of gases. Make a table for calculating the actual values of the number of supplied cylinders, related to the discreteness of the volumes of the cylinders and the switching devices themselves. Draw appropriate conclusions and make recommendations. To achieve this goal, a method was used to calculate the state of an ideal gas using software for working with spreadsheets. The article reflects the relevance of the topic and discusses the features of refueling high-voltage SF6 equipment in various climatic conditions (below minus 40-49°F). An analysis of typical ratings of high-voltage switches used at highvoltage substations was carried out. A graph is presented for converting the molar fraction (contributing to pressure) of gases into the mass fraction. A sample calculation of the number of cylinders is presented for two commonly encountered volumes of switching devices and fortyliter gas cylinders for several standard cylinder filling ratios. Presumptive conclusions are presented regarding the assessment of real errors when sending gas cylinders for refilling switching devices. The article offers an understanding of the sequence of problems associated with incorrect calculations and a complete methodology for calculating the correct volumes (mass) of gas depending on the actual types of devices used, depending on the volume of supplies pieces of equipment.

Single-photon elimination in liquid scintillation counting with pulse shape discrimination and delayed coincidence

Liquid scintillation counting is widely used in the rapid measurement of beta activity in environmental and biological samples. However, the single-photons generated by chemiluminescence and photoluminescence in liquid scintillation cocktails seriously affect the measurement accuracy of low-energy beta activity. A novel method based on the combination of the signal characteristic analysis and selective gate to eliminate the single-photon signal was developed. A preprocessing circuit made of a fast response time photomultiplier tube (PMT, Hamamatsu R9420), two charge-sensitive preamplifiers (CSP), two comparators, an analog switch and delay-line devices were designed and developed to verify the feasibility and effectiveness. The output signals from the last dynode were characterized in the pulse time and were used to discriminate the beta signals from the single-photon ones. The beta signals were “tagged” through pulse width detection, pulse width-amplitude transform and pulse-height discrimination with the first comparator, the first CSP and the second comparator. The “tagged” beta signal were applied to control the analog switch. The anode signals were specially delayed and then selected by the analog switch to achieve the single-photon signal elimination. Liquid scintillation cocktails containing 14C or NaOH used as beta or single-photon sources were provided to verify the feasibility of the principle. The results showed that the typical fall time of the single-photon and beta signal was 16.05ns and 43.17ns. The single-photon rejection ratio is 2.76 × 10−3 ± 3.89 × 10−5, and the detection efficiency is up to 93.02%±0.59%.

Design optimization of a three-dimensional hexagonal braiding technique

The three-dimensional hexagonal braiding technique, utilizing an individually controllable horn gear mechanism, enables the automatic generation of a wide range of intricate fabric preforms for structural composites. However, the limited yarn-carrying capacity and the potential risk of collisions between horn gears hinder the development of this type of braiding machine. This study proposes an optimized hexagonal braiding technique to enhance the machinery and control system, aiming to improve the yarn-carrying capacity and prevent collisions. Specifically, the optimization includes modifying the switch device, developing a new algorithm for controlling each horn gear, and designing a control panel to facilitate human–computer interaction. Additionally, simulations of various fabric structures demonstrate improved braiding capability compared to traditional hexagonal braiders. Moreover, a prototype braider is assembled, capable of automatically braiding diverse fabrics using the control system, thereby demonstrating its potential to manufacture complex composite preforms.

Seamless switching, feedforward, and feedback mechanisms: Enhancing task performance and user perception in device switch

In an era where digital multitasking is universal, the necessity to switch between devices is vital. The effect of switching modes between devices on the user experience remains unclear. This study investigates the impact of switching modes on task performance and user perception within interconnected device environments. A within-subject experiment utilizing memory recall tasks was implemented to test three switching modes: seamless switching, passive switching, and switching with feedforward and feedback. Task accuracy rate, perceived interruption, perceived control, and behavioral intention were measured. Results indicated that seamless switching outperformed passive switching in task accuracy rate. Passive switching elicited the highest level of perceived interruption, while switching with feedforward and feedback substantially improved the perceived control of users over seamless switching. The behavioral intention to use seamless switching and switching with feedforward and feedback was considerably higher than that for passive switching. This research provides insights into the comparative benefits of seamless switching and switching with feedforward and feedback, particularly regarding their influence on user perception. Practical implications for the design of interconnected device switching and the management of device ecosystems are also presented.

DC Regulation and Loop Gain Analysis of a DC-DC Switch Mode Power Supply: A Case Study on a Synchronous PWM Controlled Buck Converter

This study investigates the DC regulation of a DC-DC buck converter operating with pulse width modulation (PWM), taking into account the internal resistance of the coil and the on-resistance of the switching device. The effect of these parameters on the input/output disturbances is analyzed in continuous-conduction mode under constant frequency voltage mode control. The study also explores the effect on loop gain using the IRU3037 8-pin IC synchronous PWM controlled buck converter. The transfer function of the IRU3037 IC is derived from datasheet values using state-space averaging and AC small signal methods. A Type II compensator is then designed based on the derived transfer function. In addition, the step response characteristics of the open-loop and closed-loop circuits are investigated by time domain analysis.

Unveiling the structural, optical, electrical, and ferromagnetic properties of Ca2+ doped mixed spinel ferrites for switching field high-frequency device applications

In this paper, the calcium-doped nickel-zinc nano-ferrites [Ni0.5Zn0.5CaxFe2-xO4; x = 0.00, 0.10, and 0.30] were prepared using the chemical co-precipitation synthesis route and studied for switching field high-frequency device applications. The structural analysis has been completed by analyzing X-ray diffraction (XRD) patterns. The Rietveld refined XRD patterns confirmed the formation of cubic spinel structure of Ca2+ substituted nickel-zinc ferrites. The detection of metal-oxygen bonds present at A and B lattice sites has been unveiled by Fourier transform infrared (FTIR) spectroscopy. The morphological studies obtained through FESEM (Field emission scanning electron microscopy) analysis showed a reduction in the particle size from 70 nm to 53 nm when the concentration of Ca2+ ions in Ni-Zn ferrites was increased. Energy dispersive spectra (EDS) confirmed the presence of elements present in the prepared composition. The structure of a cubic spinel-shaped unit cell has been verified from three active prominent Raman modes (A1g, A2g, and T2g). Diffuse-reflectance spectroscopy (DRS) exhibits the increment in the bandgap values (from 1.55 eV to 1.63 eV) which helps fabricate highly efficient photovoltaic devices. The ferroelectric measurements yielded a rise in polarization values from 1.461 μC/cm2 to 18.228 μC/cm2 for 10 % Ca2+ ion substitution. The tangent loss values declined from 24 to 3 in Ni-Zn ferrites upon substituting Ca2+ ions. The Vibrating sample Magnetometer (VSM) technique found the increment in the saturation magnetization (Ms) values from 34.724 emu/g to 54.662 emu/g on substituting up to 30 % Ca2+ ions in Ni-Zn ferrites. These obtained results support the material in switching field distribution for high-frequency applications. The results exhibited that the prepared samples can be applicable for switching devices, filters, and microwave absorption devices. The results revealed the maximum frequency between 12 and 18 GHz which is useful for Ku band absorption.

Analog and digital resistive switching in W/TiO2/ITO devices: the impact of crystallinity and Indium diffusion

The resistance-switching memristor with capabilities of information storage and brain-inspired computing has prime importance in recent research. In this study, the impact of crystallinity and Indium diffusion on the existence of analog and digital resistive switching in a W/TiO2/ITO device has been reported. The memristor devices are fabricated by depositing titania films by sol–gel and spin-coating techniques. The films annealed at 250 °C and 400 °C were characterized using x-ray diffraction, Raman spectroscopy, scanning electron microscopy, and x-ray photoelectron spectroscopy (XPS). The characteristic anatase phase started appearing after annealing at 400 °C, whereas the 250 °C annealed sample was in the amorphous state. The electrical characterization revealed significant differences in the switching characteristics of amorphous and crystalline samples, especially in the switching interface, compliance properties, and current conduction mechanism. The grain boundary assisted oxygen vacancy migration, and the diffusion of indium ions from the ITO bottom electrode helped the crystalline sample to show highly stable and reproducible resistive switching compared to amorphous film. The XPS studies confirmed the indium ion diffusion in the crystalline sample. The oxygen vacancy-induced barrier modulation and conductive filament formation caused characteristic switching in amorphous and crystalline samples, respectively. Schottky emission in the amorphous film and SCLC mechanism in the crystalline film confirmed the experimental results. This study provides a distinctive viewpoint and an innovative strategy for developing multifunctional resistive switching devices.

Flexible Artificial Ag NPs:a-SiC0.11:H Synapse on Al Foil with High Uniformity and On/Off Ratio for Neuromorphic Computing.

A neuromorphic computing network based on SiCx memristor paves the way for a next-generation brain-like chip in the AI era. Up to date, the SiCx-based memristor devices are faced with the challenge of obtaining flexibility and uniformity, which can push forward the application of memristors in flexible electronics. For the first time, we report that a flexible artificial synaptic device based on a Ag NPs:a-SiC0.11:H memristor can be constructed by utilizing aluminum foil as the substrate. The device exhibits stable bipolar resistive switching characteristic even after bending 1000 times, displaying excellent flexibility and uniformity. Furthermore, an on/off ratio of approximately 107 can be obtained. It is found that the incorporation of silver nanoparticles significantly enhances the device's set and reset voltage uniformity by 76.2% and 69.7%, respectively, which is attributed to the contribution of the Ag nanoparticles. The local electric field of Ag nanoparticles can direct the formation and rupture of conductive filaments. The fitting results of I-V curves show that the carrier transport mechanism agrees with Poole-Frenkel (P-F) model in the high-resistance state, while the carrier transport follows Ohm's law in the low-resistance state. Based on the multilevel storage characteristics of the Al/Ag NPs:a-SiC0.11:H/Al foil resistive switching device, we successfully observed the biological synaptic characteristics, including the long-term potentiation (LTP), long-term depression (LTD), and spike-timing-dependent plasticity (STDP). The flexible artificial Ag NPs:a-SiC0.11:H/Al foil synapse possesses excellent conductance modulation capabilities and visual learning function, demonstrating the promise of application in flexible electronics technology for high-efficiency neuromorphic computing in the AI period.

A New Cascaded Multilevel Inverter for Modular Structure and Reduced Passive Components

In high-power applications, achieving adequate power quality in power converter design is accomplished by utilizing multilevel inverters instead of using two-level and three-level inverters. The device generates a sinusoidal output voltage, which results in reduced total harmonic distortion and lower voltage stress on the switches and leads to lower electromagnetic interference, making it suitable for use in renewable energy applications. However, to illustrate the advantages mentioned above, a significant number of switching devices and DC sources are necessary while raising the voltage levels. This article proposes an asymmetrical voltage generation method, which operates in a ratio of 1:5 and generates 25 levels using 11 power switches. The topology is modular in structure, and each module has a lower component count, which significantly reduces the overall cost. The proposed topology is capable of generating negative output voltage levels without the use of an H-bridge configuration, where only three switches are used to generate any voltage levels. The functionality of the developed module is amended by fixing different voltage values in DC sources. This article also presents a comprehensive examination of the circuit and the functioning of various voltage levels. The advantages of the proposed inverter have been demonstrated by comparative research with the currently existing MLI topologies. Ultimately, both the simulation and experimental findings validated the practical capabilities.

VOLTAGE FLICKER MITIGATION USING GTOBASED STATCOM TO IMPROVE POWER QUALITY OF A MULTI MACHINE SYSTEM

Transmission networks of modern power systems are becoming increasingly stressed because of growing demand and restrictions on building new lines. One of the consequences of such a stressed system is the threat of losing stability following a disturbance. Flexible ac transmission system (FACTS) devices are found to be very effective in a transmission network for better utilization of its existing facilities without sacrificing the desired stability margin. FACTS such as Static Synchronous Compensator (STATCOM), employ the latest technology of power electronic switching devices in electric power transmission systems to control voltage and power flow. The STATCOM adjusts voltage at its terminal by managing the amount of reactive power injected into or absorbed from the power supply. When the system voltage is low, STATCOM creates reactive power; when the system voltage is high, STATCOM absorbs reactive power. In this paper STATCOM controllers are designed for improving transient stability of multi machine systems. Proposed controllers are implemented under MATLAB/SIMULNK environment. Results of PI based controllers installed with multi machine system is found to be better on comparison with conventional system.

Dual-Band Matching Networks Using a Combination of Microstrip Lines and Active Switching Components

Active switching components are employed to propose a novel compact dual-band matching network (MN) with an adapted frequency in this paper. The design method involves the integration of active switching devices, stepped impedance resonator (SIR), and microstrip transmission line into the frequency response of a dual-band MNs. The PIN diode is employed as an active switching device in the proposed structure to increase the bandwidth of the MNs and attain the desired frequency. The dual-band MNs that are being proposed are fabricated and designed on the Rogers RO4350B substrate for use in Wireless Local Area Networks (WLANs). The simulation results demonstrate a high degree of congruence with the measurements. The maximal insertion losses and return losses in the first band are -1.3 and -24 dB, respectively. In the second band, they are -2.2 and -20.69 dB. The primary benefits of the proposed dual-band MNs are their high attenuation between two passbands, frequency matching capability, suitable return loss, and low insertion loss.

Investigating the principle and application of high-frequency and high-voltage pulse AC equipment for oil–water separation of heavy crude oil

To address the challenges of oil–water separation encountered during the processing of heavy crude oil, this study meticulously examines the kinetics of demulsification under an electric field. Consequently, a cutting-edge high-frequency/high-voltage AC pulsed power supply has been innovatively developed. This device boasts a flexible voltage-adjustment mechanism, strategically enhancing the inverter output voltage incrementally throughout the pulse’s duration. This method effectively reduces the negative impact of current surges on the operational stability of crude oil desalination plants, especially during the commutation periods of the switching devices. Furthermore, it resolves the issue of premature power supply shutdowns to the desalination plant, caused by peak currents misinterpreted as critical short-circuit currents leading to pole plate breakdowns. An industrial application study conducted at Shandong Chambroad Petrochemicals Co., Ltd. Under identical operational conditions, the power supply designed in this research outperforms traditional electrical desalting transformers in several key aspects. These include a notably enhanced oil–water separation capability and significantly more stable performance. Remarkably, the desalting efficiency shows substantial improvement even at increased feed rates, under constant other conditions. The experimental findings indicate that the average rates of desalination and dehydration achieved by this power supply exceed 90%. Moreover, even when the feed rate is augmented by approximately 75% under constant operating conditions, the desalination efficiency remains 78.49% higher than that achieved by standard industrial frequency electric desalination transformers. Additionally, the desalting outcomes are predominantly unaffected by fluctuations in the initial salt content of the feedstock, demonstrating the robustness of the developed solution.

Energy dissipation methods and protection device synergy strategies for offshore wind power receiving end surplus power

Abstract Firstly, a theoretical analysis of the fault ride-through scheme is carried out based on the land-side AC faults in the offshore wind power delivery system. According to the topological structure of the DC energy consumption device, the working mode and switching of the DC energy consumption device are analyzed and studied. Secondly, the DC protection action of offshore wind power flexible and direct transmission systems was studied, and the switching strategy of energy-consuming devices was determined. Then the impact of the switching of the energy-consuming device on the DC protection function was studied, focusing on the synergy between the DC overvoltage protection and the switching judgment voltage of the energy-consuming device. Finally, based on a typical offshore wind power flexing project, a system model is built in PSCAD/EMTDC to verify the effectiveness of the proposed synergy strategy.

Stimulus-dependent spiking and bursting behavior in memsensor circuits: experiment and wave digital modeling

Biological information processing pathways in neuron assemblies rely on spike activity, encoding information in the time domain, and operating the highly parallel network at an outstanding robustness and efficiency. One particularly important aspect is the distributed, local pre-processing effectively converting stimulus-induced signals to action potentials, temporally encoding analog information. The field of brain-inspired electronics strives to adapt concepts of information processing in neural networks, e.g., stimulus detection and processing being intertwined. As such, stimulus-modulated resistive switching in memristive devices attracts an increasing attention. This work reports on a three-component memsensor circuit, featuring a UV-sensor, a memristive device with diffusive switching characteristics and a capacitor. Upon application of a DC bias, complex, stimulus-dependent spiking and brain-inspired bursting can be observed, as experimentally showcased using combination of a microstructured, tetrapodal ZnO sensor and a Au/SiOxNy/Ag cross-point memristive device. The experimental findings are corroborated by a wave digital model, which successfully replicates both types of behavior and outlines the relation of temporal variation of switching thresholds to the occurrence of bursting activity.Graphical abstract

Investigation of recessed‐source/drain SOI feedback FET‐based integrate and fire neuron circuit with compact model of threshold switching devices

AbstractIn this article, the investigation of recessed‐source/drain (Re‐S/D) SOI feedback FET (FBFET)‐based integrate and fire (IF) neuron circuit parameters is presented using a threshold switching device compact model. FBFETs offer high ION and low SS with minimal power consumption, operating efficiently at lower voltages and currents than conventional MOSFETs. Utilizing ION/IOFF ratio and threshold voltage limits (Vt2/Vt1) of the device, a model is developed to mimic hysteresis characteristics, which is then used to implement an IF neuron circuit. Our findings show that altering the Re‐S/D thickness between 0 and 50 nm enhances the ION of the device under study while decreasing hysteresis width. We detected a significant increase in output spike frequency of 46.8% and 65.14% for input current pulse amplitudes of 5 and 20 nA, respectively. Furthermore, increasing the Re‐S/D thickness from 0 to 50 nm led to a significant 29.97% enhancement in spike amplitude. In addition, when using input current pulse amplitudes of 5 and 20 nA, we saw energy savings per spike of 3.36% and 12.7%, respectively. At the same time, there was an increase in power of 8.69% and 9.54%. These enhancements in performance metrics establish our proposed integrate and fire neuron circuit as a promising candidate for efficient neuromorphic system implementation.

Review of Nanosecond Pulse Generator With High-Power Switching Devices

Review of Nanosecond Pulse Generator With High-Power Switching Devices

Performance Analysis and Optimization of Switch Device for VLF Communication Synchronous Tuning System Based on Coupled Inductors

The very low frequency (VLF) communication system is characterized by a limited transmit bandwidth. Due to the low operating frequency, the dimensions of VLF antennas are significantly smaller than the corresponding wavelength. Therefore, VLF antennas are considered electrically small antennas (ESAs) with high Q values and narrow bandwidth. To achieve broadband VLF communication, synchronous tuning technology is commonly employed. In this study, we focus on analyzing the performance of the switching device in the synchronous tuning system using coupled inductors and IGBT as core components. By considering the equivalent circuit of the controlled source associated with coupled inductors, we propose an adaptive input impedance optimization algorithm based on the variable capacitor (hereinafter referred to as VC-ADIO) to address issues arising from coupling coefficient variations and internal parameters within IGBTs that affect primary loop input impedance. The radiated power of the VLF antenna is improved effectively.

An Enhanced Voltage Gain Techniques in Quadratic Boost Converters - A Systematic Review

High voltage gain non-isolated boost DC-DC converters are widely employed in applications such as hybrid electric vehicles, aircraft power supplies, photovoltaic (PV) systems and fuel cells (FC) applications. The use of conventional boost converters in high-gain applications is affected by their practical limitation on their voltage gain. Several boost converter topologies based on different voltage lift techniques have been studied and reported; them is quadratic boost converter (QBC). These converters have recently emerged as an interesting topology because of the quadratic nature of their voltage gain, simple among structure and simple control scheme. Recently modified topologies of QBC employing different voltage lift techniques aimed at further enhancing their performance are reported. This paper is aimed at presenting a review on the advances in quadratic boost converters topologies. In this article, QBC are categorized into five groups: magnetically coupled based on coupled-inductor (CI), switch-inductor (SI), switch-inductor switch-capacitor (SC-SI), switch-capacitor (SC), and soft-switching QBC. Furthermore, the paper makes a comprehensive comparison of various QBC in terms of voltage conversion ratio, total component count, input current ripples and voltage stress across switching devices.

Integration of Ag-based threshold switching devices in silicon microchips

Threshold-type resistive switching (RS) is an essential electronic behavior in many types of integrated circuits and can be exploited in multiple applications, such as leaky integrate-and-fire neurons for artificial neural networks (ANNs). Many research articles have shown that metal/insulator/metal (MIM) devices using Ag electrodes exhibit stable threshold-type RS, but all of them presented large devices (>1 µm2) fabricated on unfunctional SiO2/Si substrates. In this article, for the first time we integrate Ag-based threshold-type RS devices at the back-end-of-line interconnections of silicon microchips. The insulator used is multilayer hexagonal boron nitride (h-BN), and the size of the devices is ∼0.05 µm2. The devices can switch between a high resistive state (HRS) and a low resistive state (LRS) without the need of any forming process, and we observe a high endurance over 1 million cycles over multiple devices. By performing circuit simulation using SPICE software, we confirm that this electrical behavior is suitable for being used as leaky integrate-and-fire electronic neuron in spiking neural networks for image recognition, and the h-BN artificial neurons operate correctly for 94 % of the images presented. Our study represents a significant advancement towards the integration of Ag-based threshold-type RS devices in silicon microchips.