Search Results (1,126)

Pulsed Electric Fields (PEFs) are widely investigated in cancer research, yet interpretation and optimisation of exposure protocols remain challenging due to the complex interplay between electrical parameters, thermal effects, and biological response. While voltage amplitude is often emphasised, the influence of pulse timing and structure under dose-constrained conditions is less systematically examined. This work presents an exploratory in vitro study on the HepG2 hepatocellular carcinoma cell line using a custom-built bipolar pulse delivery system. Seventy experimental conditions were tested, each varying a single pulse parameter (voltage, width, period, pulses per burst, burst count, or burst period), with temperature monitored during exposure. Cell metabolic viability was quantified 24 h post-treatment using an MTT assay. The results show that short-term viability suppression and thermal behaviour depend on pulse configuration and not on total electric dose alone. Based on comparative trends, a qualitative hierarchy of parameter influence is proposed, with total electric dosage and pulse width showing the strongest association with viability reduction, followed by voltage, pulse period, pulses per burst, and burst period. Elevated temperatures observed in some regimes indicate possibly combined electro–thermal effects rather than purely electrical responses. Overall, the study provides a parameter-sensitivity overview that highlights the importance of pulse timing and thermal management alongside voltage amplitude in PEF experiments. Full article

High-Voltage Fragmentation is a novel comminution technology that utilizes shock waves generated in water by nanosecond pulsed voltages with fast rise times (<500 ns) to fracture materials, offering significant advantages in energy efficiency and environmental friendliness. This study established an underwater pulsed discharge experimental platform to meet the fast-rise-time pulse parameter requirements. It analyzed the influence patterns of the needle-mesh electrode gap distance, the needle electrode tip radius of curvature, and water conductivity on shock wave pressure intensity and time-domain characteristics. The research found that the energy conversion efficiency of underwater pulsed discharge is significantly affected by the pre-breakdown process. The peak pressure, impulse, velocity, and rise slope of the shock wave exhibit a trend of initially increasing and then decreasing with increasing needle-mesh electrode gap distance and needle electrode tip radius of curvature. The maximum pressure intensity, maximum equivalent wave velocity, maximum rise slope, and shortest wavefront time occurred at a 20 mm gap distance and a needle electrode tip curvature radius of 0.45 mm. Both pressure intensity and propagation velocity initially increased and then decreased with increasing water conductivity, reaching their maxima at a water conductivity of 340 μS/cm. Water conductivity showed no significant effect on rise slope and wavefront time. Full article

Optimizing the rectification and pressure loss controlled by the aperture structure is challenging, with particular attention paid to the problem of precisely modeling the rectification process of multilayer wire mesh in pulse tube cryocoolers. This work offers a rectifier design method based on the regularized orifice plate. A novel rectifier that reduces flow resistance and shows rectification performance comparable to a woven wire mesh is created by analyzing its effects on the flow using numerical simulation. Flow uniformity and pressure loss are selected as evaluation metrics. Point flow velocity calibration is performed under fully developed flow conditions to derive a quantitative equation relating voltage to flow velocity. A multi-cross-section radial flow velocity distribution test platform is set up. The experimental results show that the uniformity of woven wire mesh reaches 0.9670 under low-flow conditions and 0.9629 for the novel eight-ring rectifier, but the pressure drop reduction reaches 57.64%; the uniformity of the novel eight-ring rectifier is improved by 0.91~1.94% compared to that of woven wire mesh under high-flow conditions, and the pressure drop is reduced by 87.74~89.09%. The rectifier features uniformly distributed apertures, facilitating modeling and machining. Full article

The integration of high-penetration renewable energy sources (RESs) and electric vehicles (EVs) increases the risk of voltage fluctuations in distribution networks. Traditional static partitioning strategies struggle to handle the intermittency of wind turbine (WT) and photovoltaic (PV) generation, as well as the spatiotemporal randomness of EV loads. Furthermore, existing scheduling methods typically optimize EV active power or reactive compensation independently, missing opportunities for synergistic regulation. The main novelty of this paper lies in proposing a spatiotemporally coupled voltage-stability optimization framework. This framework, based on an hourly updated electrical distance matrix that accounts for RES uncertainty and EV spatiotemporal transfer characteristics, enables hourly dynamic network partitioning. Simultaneously, coordinated active–reactive optimization control of EVs is achieved by regulating the power factor angle of three-phase six-pulse bidirectional chargers. The framework is embedded within a hierarchical model predictive control (MPC) architecture, where the upper layer performs hourly dynamic partition updates and the lower layer executes a five-minute rolling dispatch for EVs. Simulations conducted on a modified IEEE 33-bus system demonstrate that, compared to uncoordinated charging, the proposed method reduces total daily network losses by 4991.3 kW, corresponding to a decrease of 3.9%. Furthermore, it markedly shrinks the low-voltage area and generally raises node voltages throughout the day. The method effectively enhances voltage uniformity, reduces network losses, and improves renewable energy accommodation capability. Full article

In flight tests, to meet the requirements of consistent acquisition and storage of multiple targets, multiple systems, and multiple data types, various data types are processed into Pulse Code Modulation (PCM) data streams using PCM encoding for storage. Aiming at the requirement of real-time storage of high-bit-rate PCM data streams, a large-capacity storage system based on Serial Advanced Technology Attachment 3.0 (SATA3.0) is designed. The system uses the Kintex 7 series Field-Programmable Gate Array (FPGA) as the control core, receives PCM data streams through the Low-Voltage Differential Signaling (LVDS) low-voltage differential interface, stores the received PCM data streams into the mSATA disk via the SATA3.0 transmission bus, and transmits the stored data back to the host computer through the USB3.0 interface for analysis. Meanwhile, to solve the problem of complex data export, the storage system constructs a FAT32 file system through the MicroBlaze soft core to optimize the management and operation of the large-capacity storage system. Test results show that the storage system can perform stable high-rate storage at −40 °C~80 °C. Full article

Achieving high reliability remains the critical challenge for pulsed power supplies (PPS), whose core components are susceptible to severe degradation and catastrophic failure due to long-term operation under electrical, thermal and magnetic stresses, particularly those associated with high voltage and high current. This reliability challenge fundamentally limits the widespread deployment of PPSs in defense and industrial applications. This article provides a comprehensive and systematic review of the reliability challenges and recent technological progress concerning PPSs, focusing on three hierarchical levels: component, system integration, and extreme operating environments. The review investigates the underlying failure mechanisms, degradation characteristics, and structural optimization of key components, such as energy storage capacitors and power switches. Furthermore, it elaborates on advanced system-level techniques, including novel thermal management topologies, jitter control methods for multi-module synchronization, and electromagnetic interference (EMI) source suppression and coupling path optimization. The primary conclusion is that achieving long-term, high-frequency operation depends on multi-physics field modeling and robust, integrated design approaches at all three levels. In summary, this review outlines important research directions for future advancements and offers technical guidance to help speed up the development of next-generation PPS systems characterized by high power density, frequent repetition, and outstanding reliability. Full article

The pulsed power switch serves as a critical component in pulsed power systems. The electric radiation generated by switching operations threatens the miniaturization of pulsed power systems, causing significant electromagnetic interference (EMI) to nearby signal circuits. The pseudospark switch’s (PSS) exceptionally fast transient response, a key enabler for sophisticated pulsed power systems, is also a major source of severe EMI. This study investigated the electric field radiation from a high voltage PSS within a capacitor discharge unit (CDU), using a near-field scanning system based on an electro-optic probe. The time-frequency distribution of the radiation was characterized, identifying contributions from three sequential stages: the application of the trigger voltage, the main gap breakdown, and the subsequent oscillating high voltage. During the high-frequency oscillation stage, the distribution of the peak electric field radiation aligns with the predictions of the dipole model, with a maximum value of 43.99 kV/m measured near the PSS. The spectral composition extended to 60 MHz, featuring a primary component at 1.24 MHz and distinct harmonics at 20.14 MHz and 32.33 MHz. Additionally, the impacts of circuit parameters and trigger current on the radiated fields were discussed. These results provided essential guidance for the electromagnetic compatibility (EMC) design of highly-integrated pulsed power systems, facilitating more reliable PSS applications. Full article

The ultra-high frequency (UHF)-based partial discharge (PD) detection technology for gas-insulated switchgear (GIS) has achieved large-scale applications due to its high sensitivity and real-time monitoring capabilities. However, long-term service-induced antenna corrosion in UHF sensors may lead to degraded reception characteristics. To ensure the credibility of monitoring data, on-site sensor calibration under ambient noise conditions is required. This study first analyzes the time–frequency domain characteristics of white noise received by UHF sensors in GIS environments. Leveraging the transceiver reciprocity principle of sensors, a noise reconstruction method based on external sensors is proposed to simulate on-site white noise. Subsequently, CST simulation models are established for both standard and degraded sensors, quantifying the impact of factors like antenna corrosion on performance parameters such as echo impedance S11 and voltage standing wave ratio (VSWR). Finally, the two sensor models are coupled into GIS handholes for comparative simulation analysis. Results show that antenna corrosion causes resonant frequency shifts in sensors, reducing PD signal power by 55.27% and increasing noise power by 64.11%. The signal-to-noise ratio (SNR) decreases from −9.70 dB to −15.34 dB, with evident waveform distortion in the double-exponential PD pulses. These conclusions provide theoretical references for on-site UHF sensor calibration in noisy environments. Full article

The camera is a core device for modern surveillance and data collection, widely used in various fields including security, transportation, and healthcare. However, their widespread deployment has proportionally escalated associated security risks. This paper initially examines the current state of research on attack methods targeting camera systems, providing a comprehensive review of various attack techniques and their security implications. Subsequently, we focus on a specific attack method against universal serial bus (USB) cameras, known as electromagnetic pulse (EMP) attacks, which utilize EMP to prevent the system from detecting the cameras. We simulated EMP attacks using a solar insecticidal lamp (which generates EMP by releasing high-voltage pulses) and a commercially available EMP generator. The performance of the cameras under various conditions was evaluated by adjusting the number of filtering magnetic rings on the USB cable and the distance between the camera and the interference source. The results demonstrate that some USB cameras are vulnerable to EMP attacks. Although EMP attacks might not invariably cause image distortion or permanent damage, their covert nature can lead to false detection of system failures, data security, and system maintenance. Based on these findings, it is recommended to determine the optimal number of shielding rings for cameras or their safe distance from EMP sources through the experimental approach outlined in this study, thereby enhancing the security and resilience of USB camera enabled systems in specific scenarios. Full article

Induction motors (IMs) are widely used in variable-speed electric drive systems, where the motor is supplied by a voltage source inverter (VSI). Thus, PWM inverter–IM combination presents several issues that can degrade system performance, particularly overvoltage phenomena when long cables are used. In inverter-fed drive systems, the physical separation between the converter and the motor often requires long motor cables, which can significantly affect voltage stress. As the inverter’s output pulses propagate through the cable, voltage reflections and high-frequency oscillations occur at the motor terminals. We theoretically and experimentally investigate the effect of three PWM methods, namely Space Vector (SVPWM), Selective Harmonic Elimination PWM (SHEPWM), and Random PWM (RPWM) strategies, on overvoltage at the terminals of an induction motor fed by a PWM inverter through a long cable. The simulation results exhibit the validity and efficiency of SVPWM control to reduce overvoltage for different cable lengths. In addition, in order to reduce and eliminate all overvoltage peaks, three filters are proposed and evaluated: an RC filter, an RLC filter, and a compensator. The proposed PWM strategies are assessed using equivalent experimental results obtained on an induction motor fed by a two-level VSI. The experimental tests demonstrate also the efficiency of the SVPWM compared to other strategies. Full article

Traditional colloid SERS substrates are mostly based on metal nanoparticles (MNPs), which have complex and time-consuming fabrication processes, poor structural control, and are susceptible to oxidation. As a result, solid-state SERS substrates have emerged as an effective alternative. Here, we propose using two-step mild and hard anodization to fabricate ordered anodic aluminum oxide (AAO) substrates with high total pore circumference for SERS detection. Hybrid pulse anodization (HPA) enables the fabrication of AAO at room temperature using 40 V in the first step and 40, 110, and 120 V in the second step of anodization. The different voltages applied in the second step effectively control the pore diameter, thereby achieving various nanostructures. The enhancement mechanism primarily originates from the high total pore circumference of nanostructures, which generates abundant hot spots around the pore peripherals, thereby significantly amplifying the SERS signal. Sorbic acid is a common preservative widely used in food products and employed as a test substance on high regularity AAO substrates at concentrations of 1000 ppm to 10 ppb. The resulting SERS spectra exhibited distinct characteristic peaks at 1640–1645 cm⁻¹. The analytical enhancement factor is calculated as 1.02 × 10⁵ at the AAO substrate prepared by 110 V with the Si substrate as the reference. By appropriately tuning the process parameters, a limit of detection (LOD) as low as 10 ppb of sorbic acid was achieved. Full article

The performance of true random number generators (TRNGs) fundamentally depends on the quality of their entropy sources (ESs). However, many FPGA-friendly designs still rely on a single mechanism and struggle to achieve both high throughput and low resource cost. To address this challenge, we propose the exclusive OR (XOR) Self-Feedback Ring Oscillator (XORSFRO), an XORNOT-style TRNG that integrates two cross-connected XOR gates with a short inverter delay chain and clocked sampling. A unified timing model is developed to describe how arrival-time skew and gate inertial delay lead to cancellation, narrow-pulse generation, and inversion events, thereby enabling effective entropy extraction. Experimental results on Xilinx Spartan-6 and Artix-7 FPGAs demonstrate that XORSFRO maintains stable operation across standard process–voltage–temperature (PVT) variations, while achieving higher throughput and lower hardware overhead compared with recent FPGA-based TRNGs. The generated bitstreams pass both the NIST SP 800-22 and NIST SP 800-90B test suites without post-processing. Full article

In this paper, we propose a novel concept of a modular, multiport, single-stage, bidirectional, isolated, three-phase AC-DC converter system. This new system is realized using add-ons to a standard voltage source inverter, including both grid-connected AC-DC converters, like PWM rectifiers, and AC-drive DC-AC inverters. The proposed add-on converters provide isolated DC ports and can be installed into existing inverters of the abovementioned types, with no need for any modification of their topology or control system. Moreover, the add-on converters provide a minimum transistor count and high efficiency. The efficiency of the proposed add-on converters can be further improved by switching the type of pulse width modulation (PWM) scheme based on their operating point. The proposed converter system is validated for a power of 20 kW, an output voltage of 500–800 V DC, and a 40 kHz PWM frequency. Full article

The paper studied the effect of high-voltage short-pulse electrohydraulic discharge (HVSPED) on the processes of catalytic cracking of oil sludge in order to increase the yield of light hydrocarbon fractions. A set of laboratory experiments was carried out varying the key parameters of HVSPED—discharge voltage, capacitance of capacitor banks and processing time. As a catalyst, the developed nanocomposite catalyst bentonite was used, with nickel packed. The optimal electrophysical parameters of oil sludge treatment by HVSPED were determined, providing the maximum yield of gasoline and kerosene fractions. The effectiveness of HVSPED treatment of oil sludge in the presence of a catalyst was confirmed by DTA–thermogravimetric analysis and chromatographic-mass spectral analysis of the light and middle fractions of the hydrogenate. The proposed approach made it possible to enhance the resource and energy efficiency of oil sludge processing using HVSPED, demonstrating high potential for further industrial application Full article

This work presents a highly compact and scalable 1.2-kV SiC MOSFET half-bridge building-block module enabled by a die-integrated 3D PCB packaging technology. Compared with conventional DBC-based or TO-247-based SiC half-bridge modules, the proposed design reduces the physical volume and weight by more than 90% while maintaining full compatibility with standard PCB manufacturing processes. The vertically laminated DC+/DC− conductors and symmetric PCB–die–PCB stack establish a tightly confined commutation loop, resulting in a measured power-loop inductance of 2.2 nH and a 3.8 nH gate-loop inductance—representing up to 94% and 89% reduction relative to discrete device implementations. Because the parasitic parameters are intrinsically well-balanced across replicated units and the mutual inductance between adjacent modules remains extremely small, the structure naturally supports current sharing during parallel operation. Thermal and insulation evaluations further confirm the suitability of copper filling via high-Tg laminated PCB substrates for high-power SiC applications, achieving withstand voltages exceeding twice the rated bus voltage. The proposed module is experimentally validated through finite-element parasitic extraction and 950 V double-pulse testing, demonstrating controlled dv/dt behavior and robust switching performance. This work establishes a manufacturable and parallel-friendly packaging approach for high-density SiC power conversion systems. Full article