Search Results (505)

This paper presents the results of modeling the DC and dynamic characteristics of an alkaline electrolyzer. A model of such an electrolyzer is proposed as a subcircuit for the SPICE software. This model describes DC and dynamic current–voltage characteristics of the electrolyzer, taking into account the effect of solution concentration on the electrolyzer internal resistance and electrolyte capacitance, as well as the resistance and inductance of the leads. Using this model, one can calculate the voltage and current waveforms across the electrolyzer, as well as the gas flow rate produced by the electrolyzer. The correctness of the developed model was experimentally verified by powering the electrolyzer using a DC source and by powering the device using a voltage source, generating a rectangular pulse train with an adjustable frequency and duty cycle. The measurement system is described, and the obtained calculation and measurement results are presented and discussed. It was shown that the obtained calculation results differed minimally from the measurement results across a wide range of frequencies (from 0 to 50 kHz), duty cycles (from 0.3 to 0.7) of the supply voltage, and concentrations of the electrolyte (from 0.1 to 10%). The mean square error, normalized to peak measured values of each considered quantity, does not exceed 4%. 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

Polycystic Ovary Syndrome (PCOS) is characterized by a self-perpetuating vicious cycle between insulin resistance (IR) and hyperandrogenism (HA). While lifestyle management remains the internationally recommended first-line treatment, current clinical management, primarily relying on combined oral contraceptives and metformin, offers symptomatic relief or “masking” of the phenotype but fails to adequately disrupt this core pathophysiological loop, while also carrying potential intergenerational safety concerns. This review systematically evaluates the paradigm shift toward mechanism-based precision medicine. First, we analyze emerging precision-targeted therapies that intervene in specific pathological nodes: (1) metabolic regulators (e.g., GLP-1RAs, SGLT2i, and brown adipose tissue (BAT) activators) that target systemic glucotoxicity and the novel “BAT-Ovarian axis”; (2) neuroendocrine modulators (e.g., NK3R antagonists) that act as negative modulators of the hyperactive GnRH pulse generator; and (3) innovative androgen synthesis inhibitors (e.g., Artemisinins) that utilize a degradation-at-source mechanism. Complementing these, we explore the strategic value of Natural Products through the lens of “Network Pharmacology”, highlighting their ability to restore systemic homeostasis via multi-target modulation. Finally, we address critical translational challenges, specifically the need to establish long-term reproductive and offspring safety, providing a roadmap for developing true disease-modifying treatments for PCOS. Distinct from reviews limited to isolated therapeutic modalities, this article uniquely bridges current clinical management with emerging organ-specific precision targets and natural product networks. Full article

With the increasing integration of renewable energy sources into the grid, power quality at the point of common coupling (PCC)—particularly harmonic distortion introduced by power electronic converters—has become a critical concern. This paper presents a rigorous design and evaluation of a three-phase, fifteen-level cascaded H-bridge multilevel inverter (CHB MLI) with an LCL filter, selected for its superior harmonic attenuation, compact size, and cost-effectiveness compared to conventional passive filters. The proposed system employs Phase-Shifted Pulse Width Modulation (PS PWM) for balanced operation and low output distortion. A systematic, reproducible methodology is used to design the LCL filter, which is then tested across a wide range of switching frequencies (1–5 kHz) and grid impedance ratios (X/R = 2–9) in MATLAB/Simulink R2025a. Comprehensive simulations confirm that the filter effectively reduces both voltage and current total harmonic distortion (THD) to levels well below the 5% limit specified by IEEE 519, with optimal performance (0.53% current THD, 0.69% voltage THD) achieved at 3 kHz and X/R ≈ 5.6. The filter demonstrates robust performance regardless of grid conditions, making it a practical and scalable solution for modern renewable energy integration. These results, further supported by parametric validation and clear design guidelines, provide actionable insights for academic research and industrial deployment. 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 proper control of cathode spot motion is the key issue in the application of vacuum arc deposition (VAD). Improving the arc spot discharge requires considering the structure and properties of the deposited films/coatings as well as the deposition velocity, target utilization, etc. To achieve this goal, it is necessary to precisely observe cathode spots during discharge at both microscopic and macroscopic scales. However, how to capture the motion and splitting behavior of cathode spots using simple equipment remains an open question. In this work, we analyze the motion and the splitting behavior of cathode spots considering industry application on a Cr target for VAD under arc currents in the direct mode (70 A, 100 A, 150 A 200 A) and 400 A as a peak value in the pulse mode with two applied magnetic fields (20 Gs and 40 Gs) at the macroscopic scale using a high-speed digital camera, employing different exposure times under an extracted interval of 1 ms ranging from 0.01 ms to 20 ms. Furthermore, the images are also compared when the interval is extended to 2 ms and 4 ms. Considering all factors in the available data, 0.05 ms is suggested as the best exposure time, and 1 ms is suggested as the most suitable extracted interval for cathode spot observation under these conditions. Hopefully, this paper provides a suitable technique for observing the motion and splitting behavior of cathode spots at a macroscopic scale with the purpose of suppressing/eliminating the injection of macroparticles at the source for industrial VAD coating products of high quality. 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

This paper introduces a novel control archetype designed to mitigate high-altitude electromagnetic pulse (HEMP) $E_3$ disturbances on the power grid, as well as information on performance and specifications of different control laws for the controller archetype. This method of protection has been overlooked in the literature until now. A controlled voltage supply is placed on the load-side of a transformer, diverting unwanted power from the transformer core to prevent saturation. The controlled voltage source is modeled using four control laws: an integral controller (capacitor), Linear Quadratic Regulator (LQR), an energy storage minimized feedforward control law, and a Hamiltonian feedback law. Results show that the Hamiltonian feedback law and the energy storage minimization feedforward control law both flat-line magnetic flux with similar actuator requirements. The LQR approach requires less energy storage than the other two laws, depending on control tuning, as it allows greater exogenous current flow through the neutral path to ground. This leads to further optimization opportunities based on acceptable exogenous current levels. A sweep of different LQR gains revealed a reduction of approximately $32\%$ in minimum control effort, $47\%$ in minimum power to maintain saturation bounds, $20\%$ in energy storage requirements, and $59\%$ in required controller bandwidth. Voltage and bandwidth requirements of the load-side controller are comparable to neutral blocking requirements with energy and power requirements being higher for the load-side controller. This, however, comes with the benefit of being able to use pre-existing assets—neutral blocking devices have not been deployed. Additionally, the load-side blocking capacitor degrades transformer performance compared to the unmitigated system. Full article

This review presents a critical and comparative analysis of carbon-based electrochemical sensing platforms for the determination of heavy metal ions in water, with emphasis on Pb²⁺, Cd²⁺, and Hg²⁺. The growing discharge of industrial and mining effluents has led to persistent contamination of aquatic environments by toxic metals, creating an urgent need for sensitive, rapid, and field-deployable analytical technologies. Carbon-based nanomaterials, including graphene, carbon nanotubes (CNTs), and MXene, have emerged as key functional components in modern electrochemical sensors due to their high electrical conductivity, large surface area, and tunable surface chemistry. Based on reported studies, typical detection limits for Pb²⁺ and Cd²⁺ using differential pulse voltammetry (DPV) on glassy carbon and thin-film electrodes are in the range of 0.4–1.2 µg/L. For integrated thin-film sensing systems, limits of detection of 0.8–1.2 µg/L are commonly achieved. MXene-based platforms further enhance sensitivity and enable Hg²⁺ detection with linear response ranges typically between 1 and 5 µg/L, accompanied by clear electrochemical or optical signals. Beyond conventional electrochemical detection, this review specifically highlights self-sustaining visual sensors based on MXene integrated with enzyme-driven bioelectrochemical systems, such as glucose oxidase (GOD) and Prussian blue (PB) assembled on ITO substrates. These systems convert chemical energy into measurable colorimetric signals without external power sources, enabling direct visual identification of Hg²⁺ ions. Under optimized conditions (e.g., 5 mg/mL GOD and 5 mM glucose), stable and distinguishable color responses are achieved for rapid on-site monitoring. Overall, this review not only summarizes current performance benchmarks of carbon-based sensors but also identifies key challenges, including long-term stability, selectivity under multi-ion interference, and large-scale device integration, while outlining future directions toward portable multisensor water-quality monitoring systems. Full article

With the development of distributed energy sources such as photovoltaic and wind power, power grids have imposed increasingly higher requirements on power quality. As common nonlinear loads in power grids, multi-pulse rectifiers (MPRs) inject significant harmonics into the grid side. To reduce harmonic pollution at the source, this paper proposes a novel triple-passive harmonic suppression method to reduce the input current harmonics of MPRs. The proposed 48-pulse rectifier comprises a main circuit based on delta-connected auto-transformer (DCT) and a triple-passive harmonic suppression circuit (TPHSC). The TPHSC consists of two interphase reactors (IPRs) and eight diodes. Based on Kirchhoff’s Current Law (KCL), the output currents of the main circuit are calculated, and the operating modes of the TPHSC are analyzed. From the main circuit’s output currents and the DCT topology, the rectifier’s input currents are derived, and the optimal turns ratio of the IPRs for minimizing the input current total harmonic distortion (THD) is determined. The total capacity of the IPRs accounts for only 2.3% of the output load power. Experimental results show that the measured input current THD is close to the theoretical value of 3.8%. Overall, the proposed rectifier offers a cost-effective solution with stronger harmonic suppression capability, making it suitable for applications requiring low grid harmonic pollution. Full article

Multi-sensor systems require precise time synchronization for accurate data fusion. However, currently prevalent software time synchronization methods often rely on clocks provided by the Global Navigation Satellite System (GNSS), which may not offer high accuracy and can be easily affected by issues with GNSS signals. To address this limitation, this study introduces a novel laser pulse-driven time synchronization (LPTS) method in our custom-developed Light Detecting and Ranging (LiDAR) system. The LPTS method uses electrical pulses, synchronized with laser beams as the time synchronization source, driving the Micro-Controller Unit (MCU) timer within the control system to count with a timing accuracy of 0.1 $\mathsf{\mu }$s and to timestamp the data from the Positioning and Orientation System (POS) unit or laser scanner unit. By employing interpolation techniques, the POS and laser scanner data are precisely synchronized with laser pulses, ensuring strict correlation through their timestamps. In this article, the working principles and experimental methods of both traditional time synchronization (TRTS) and LPTS methods are discussed. We have implemented both methods on experimental platforms, and the results demonstrate that the LPTS method circumvents the dependency on external time references for inter-sensor alignment and minimizes the impact of laser jitter stemming from third-party time references, without requiring additional hardware. Moreover, it elevates the internal time synchronization resolution to 0.1 $\mathsf{\mu }$s and significantly improves relative timing precision. Full article

Future space detectors for Ultra High Energy neutrinos and cosmic rays will utilize Cherenkov telescopes to detect forward-beamed Cherenkov light produced by charged particles in Extensive Air Showers (EASs). A Cherenkov detector can be equipped with an array of Silicon Photo-Multiplier (SiPM) pixels, which offer several advantages over traditional Photo-Multiplier Tubes (PMTs). SiPMs are compact and lightweight and operate at lower voltages, making them well-suited for space-based experiments. The SiSMUV (SiPM-based Space Monitor for UV-light) is developing a SiPM-based Cherenkov camera for PBR (POEMMA Baloon with Radio) at INFN Napoli. To understand the response of such an instrument, a comprehensive simulation of the response of individual SiPM pixels to incident light is needed. For the accurate simulation of a threshold trigger, this simulation must reproduce the current produced by a SiPM pixel as a function of time. Since a SiPM pixel is made of many individual Avalanche Photo-Diodes (APDs), saturation and pileup in APDs must also be simulated. A Gaussian mixture fit to ADC count spectrum of a SiPM pixel exposed to low levels of laser light at INFN Napoli shows a significant amount of samples between the expected PE (Photo Electron) peaks. Thus, noise sources such as dark counts and afterpulses, which result in partially integrated APD pulses, must be accounted for. With static, reasonable values for noise rates, the simulation chain presented in this work uses the characteristics of individual APDs to produce the aggregate current produced by a SiPM pixel. When many such pulses are simulated and integrated, the ADC spectra generated by low levels of laser light at the INFN Napoli SiSMUV test setup can be accurately reproduced. Full article

The whole-plant preferential allocation patterns of recently assimilated carbon by the source leaves of six-year-old cork oaks (Quercus suber L.) were assessed 7 days after a ¹⁴CO₂ pulse-labelling in late spring (end of May). The ¹⁴CO₂ assimilation was separately induced on attached leaves on branches located at the top-down 30% of the crown height, in the middle 40% and at the bottom-up 30% of the crown height of twelve plants. Our results showed that the top source leaves retained the highest amount (64%) of their own current produced carbohydrates compared to either lower (49%) or middle (42%) source leaves. The top source leaves preferentially export current carbohydrates to their most proximal sinks, namely, other leaves or their branches. However, lower source leaves exported the highest amount of current carbon, about 37%, preferentially to the root system. Roots displayed the greatest sink strength for the available current carbohydrates, due to their largest biomass (between 69% and 75% of the whole plant biomass), when other strong sinks, such as the annual leaves, were fully expanded. Taken together, our data revealed that carbon supply by leaves and delivery to roots are critical for maintaining root growth in cork oak under Mediterranean seasonal drought conditions. Full article

Aperiodic pseudo-random impulse (APPI) trains represent deterministic yet reproducible sequences that mimic the irregularity of natural processes. They allow complete control over inter-spike intervals (ISIs) and pulse widths (PWs). Such signals are increasingly relevant for low-probability-of-intercept (LPI) communications, radar testing, and biomedical applications, where controlled variability mitigates adaptation and enhances stimulation efficiency. This paper presents a modular APPI generator implemented on an Arduino Mega platform, featuring programmable statistical models for ISI (exponential distribution) and PW (uniform distribution), dual-timing mechanisms (baseline loop and Timer/ISR, clear-timer on compare (CTC)), a real-time telemetry and software interface, and a safe output chain with opto-isolation and current limitation. The generator provides both reproducibility and tunable stochastic dynamics. Experimental validation includes jitter analysis, Kolmogorov–Smirnov tests, Q–Q plots, spectral and autocorrelation analysis, and load integration using a constant-current source with compliance margins. The results demonstrate that the Timer/ISR (CTC) implementation achieves significantly reduced jitter compared to the baseline loop, while maintaining the statistical fidelity of ISI and PW distributions, broad spectral characteristics, and fast decorrelation. Experimental verification was extended across a wider parameter space (λ = 0.1–100 Hz, PW = 10 µs–100 ms, 10 repetitions per condition), confirming robustness and repeatability. Experimental validation confirmed accurate Poisson/Uniform ISI generation, sub-millisecond jitter stability in the timer-controlled mode, robustness across λ = 0.1–100 Hz and PW = 10 µs–100 ms, and preliminary compliance with isolation and leakage limits. The accompanying Python GUI provides real-time control, telemetry, and data-logging capabilities. This work establishes a reproducible, low-cost, and open-source framework for APPI generation, with direct applicability in laboratory and field environments. Full article

This study presents the development of a buck–boost converter for application in unmanned guided vehicles (UGVs). The converter was designed with its input connected to a lithium iron phosphate battery pack and its output connected to an inverter. This configuration enabled the inverter, which powered the drive motor, to receive a stable DC voltage, thereby mitigating the effects of battery voltage fluctuations and enhancing the overall system stability. A pulse-width modulation (PWM) controller was employed to regulate the developed buck–boost converter. During the transition from buck mode to buck–boost mode, both power MOSFETs were simultaneously turned on; however, the datasheet of the PWM controller did not provide operational details or characteristic curve analysis for this mode. Therefore, this study derived the relationship between voltage gain and duty cycle ratio for the transition mode. To analyze the input voltage versus duty cycle characteristics, the linear equation was employed. This analytical model was adjusted to meet different converter specifications developed for experimental validation. Furthermore, the external-connect test capacitor method was used to extract the equivalent parasitic inductance and capacitance present in the practical circuit of the buck–boost converter. Based on these parameters, a snubber circuit was designed and connected across the drain–source terminals of the power MOSFETs to suppress voltage spikes occurring at the junctions. Finally, the developed buck–boost converter prototype was installed on an unmanned guided vehicle to convert the power from the lithium battery pack into the input power required by two inverters. A computer host was used to control the motor speed. By measuring the output voltage and current of the buck–boost converter, its electrical functionality and performance specifications were verified. The dimensions of the developed UGV chassis prototype were 40 cm in length, 45 cm in width, and 18.3 cm in height. Full article