Search Results (8,438)

The paper shows the construction and operation of the High-Voltage High-Frequency Coaxial Cable Energy Transfer System dedicated to a three-phase 500 V mining grid with an ungrounded neutral point. The correct operation of the model was verified through simulation and experiments. This paper focuses on the overall system efficiency and the power loss analysis of its components. Based on these measurements, it is concluded that the presented system is suitable for mining applications, where high energy conversion efficiency is essential due to the difficulty of dissipating heat to the environment. Full article

Wind power systems often introduce interfering DC components that distort power measurements and threaten grid stability. To address these issues, this paper proposes a novel delayed sampling-based grid parameter estimation method that explicitly accounts for DC disturbances. By transforming the estimation problem into a linear regression form via nonlinear algebraic transformation, an adaptive recursive identification algorithm is developed to estimate grid frequency, amplitude, phase, and DC component simultaneously. Rigorous stability analysis is provided to guarantee convergence and robustness of the estimator in the presence of DC components. Experimental results demonstrate fast transient response and zero steady-state error, validating the effectiveness of the proposed method for real-time grid parameter estimation. Full article

Accurate prediction of the performance of an internal combustion engine is an essential step towards achieving efficiency and complying with emission standards. This study presents an artificial neural network (ANN) model that uses sensor-derived parameters, such as design power, wheel power, torque, and rotational speed, to predict engine load. Data were collected from a dynamometer and a hardware-in-the-loop (HiL) setup to ensure realistic, sensor-based measurements. The proposed ANN architecture achieved high accuracy (99%) in multiclass classification and strong regression performance ($R^2\approx 0.98$), demonstrating its ability to model complex engine load relationships under normal operating conditions. Performance was validated using 5-fold stratified cross-validation, achieving an average accuracy of $0.988\pm 0.011$, macro-F1 of $0.984\pm 0.011$, and regression $R^2$ of $0.962\pm 0.052$, confirming strong generalization and robustness. The model can be extended to include additional sensor inputs and adapted for use with other powertrain systems, allowing it to be used in a range of automotive and industrial applications. Full article

This article presents the design of a perovskite photovoltaic (PV)-based power management system, which uses a power converter (a four-stage bootstrap charge pump) to boost the output of the solar cell and supply selectable rectified power rails to CMOS image sensor circuit blocks. A perovskite photovoltaic, also known as a perovskite solar cell (PSC) was fabricated in the laboratory. The PSC has an open-circuit voltage of 1.14 V, short-circuit current of 1.24 mA, maximum power of 0.88 mW, and a current density of 20.68 mA/cm² at 62% fill factor. These measured forward scan parameters were closely reproduced with a solar cell simulation model. In a Cadence simulation that used 180 nm CMOS process, the power converter efficiently boosts the maximum output voltage of the PSC from 0.85 V to a rectified 3.7 V. Stage modulation and level shifting enable selectable output rails in the 1.2–3.3 V range to supply the image sensor circuit blocks. Keeping the output capacitance of the power converter much larger than the flying capacitance reduces the ripple voltage to approximately 73 µV, much smaller than the typical 1 mV in several other literatures. Through simulation, this work demonstrates the concept of directly using PSC (to be implemented on an outer ‘packaging’, not on a die) to supply CMOS image sensor power rails, in the same sense as in wearable devices and other consumer devices. This work highlights a path toward self-powered image sensors with improved conversion efficiency, compactness, and adaptability in low-light and variable operating environments. Full article

The rapid expansion of renewable energy has posed significant challenges for the power system, including supply adequacy and operational flexibility. Nuclear power, as a stable and clean baseload source, plays a significant role in developing a new-type power system. However, its weak modulation capabilities significantly constrain its peak shaving and frequency regulation performance. The integrated operation of nuclear power and pumped storage, known as “nuclear-pumped storage integration”, can not only compensate for energy shortages but also provide auxiliary services, making it a viable solution for ensuring regional power supply stability. Nevertheless, a significant problem resides in achieving an appropriate benefit allocation between the two entities. To solve this issue, this research presents a mechanism for measuring and allocating the benefits of “nuclear-pumped storage integration” operation in a diverse power market. First, an integrated operating model is built, together with a joint clearing model encompassing the spot energy market and frequency modulation ancillary service market. A full-chain cost–benefit accounting system is designed to evaluate the value of joint operations accurately. Second, by incorporating indicators such as peak-shaving compensation and participation degree, a benefit allocation correction factor is derived, and an improved Shapley value approach is proposed to enhance the rationality and incentive effect of the allocation scheme. Case study results suggest that the “nuclear-pumped storage integration” operation mode can significantly increase overall benefits. Moreover, compared with existing techniques, the suggested improved Shapley value method provides fairness and rationality in benefit allocation, offering a sound decision-making basis for advancing the “nuclear-pumped storage integration” model. Full article

The electric power grid constitutes a foundational pillar of modern critical infrastructure (CI), underpinning societal functionality and global economic stability. Yet, the increasing convergence of Information Technology (IT) and Operational Technology (OT), particularly through the integration of Supervisory Control and Data Acquisition (SCADA) and Industrial Control Systems (ICS), has amplified the sector’s exposure to sophisticated cyber threats. This study conducts a comparative analysis of five major cyber incidents targeting electric power systems: the 2015 and 2016 Ukrainian power grid disruptions, the 2022 Industroyer2 event, the 2010 Stuxnet attack, and the 2012 Shamoon incident. Each case is examined with respect to its objectives, methodologies, operational impacts, and mitigation efforts. Building on these analyses, the research evaluates the extent to which such attacks could have been prevented or mitigated through the systematic adoption of leading cybersecurity maturity frameworks. The NIST Cybersecurity Framework (CSF) 2.0, the ENISA NIS2 Directive Risk Management Measures, the U.S. Department of Energy’s Cybersecurity Capability Maturity Model (C2M2), and the Cybersecurity Risk Foundation (CRF) Maturity Model alongside complementary technical standards such as NIST SP 800-82 and IEC 62443 have been thoroughly examined. The findings suggest that a proactive, layered defense architecture grounded in the principles of these frameworks could have significantly reduced both the likelihood and the operational impact of the reviewed incidents. Moreover, the paper identifies critical gaps in the existing maturity models, particularly in their ability to capture hybrid, cross-domain, and human-centric threat dynamics. The study concludes by proposing directions for evolving from compliance-driven to resilience-oriented cybersecurity ecosystems, offering actionable recommendations for policymakers and power system operators to strengthen the cyber-physical resilience of electric generation and distribution infrastructures worldwide. Full article

An MMC is widely applied to the HVDC power transmission system. With a large number of insulated gate bipolar transistors (IGBTs) utilized in MMC-HVDC converter stations, an extremely complicated EM environment is generated due to the dv/dt and di/dt during the IGBT switching process. A magnetic field simulation model is proposed to calculate the magnetic field generated by a 4.5 kV/5 kA IGBT-based MMC submodule under the DPT, with the dynamic switching behavior of IGBTs considered. Firstly, a behavior model of 4.5 kV/5 kA IGBTs is built with the help of commercial software. To validate its effectiveness, a DPT simulation model is built. A comparison between the simulation result and the measured data is performed. Finally, a quasi-static Maxwell model is utilized to approximate the near field caused by the current Ic of the DPT. The simulation result of the magnetic field strength at the point near the gate driver PCB is verified by the measurement data. The proposed magnetic field simulation model can help to analyze the EMI behavior and EMI design for MMC-HVDC submodules under DPT. Full article

Background: This study explored the potential of a passive exoskeleton (Exo) to improve cadence, step length, oxygen uptake, and reduce metabolic power in senior adults, with the expectation that slow walkers (SW < 0.56 m/s) would benefit more than intermediate walkers (IW ≥ 0.56 m/s). Methods: Twenty-three senior adults walked on a treadmill at their self-selected speed using the Exo, noExo, and a placebo (Sham) in a randomized and balanced order. A lower back inertial measurement unit, a heart rate monitor, and an oxygen uptake system were used to monitor spatiotemporal and cardiopulmonary parameters. Cadence, step length, heart rate, oxygen uptake (V̇O₂ and relativeV̇O₂), metabolic power, and respiratory exchange ratio were extracted. A two-way MANOVA was performed across Exo vs. noExo vs. Sham and SW vs. IW. Results. Using Exo did not show any significant changes in spatiotemporal or cardiopulmonary outcomes compared to the conditions for both SW and IW. IW vs. SW seniors had significantly higher cadence (15–19%), step length (31–41%), relativeV̇O₂ (21–23%), and metabolic power (21–23%) in all devices (p < 0.05). Conclusions: These findings show that the use of Exo among senior adults does not improve spatiotemporal parameters nor reduce metabolic powers even among SW. Full article

The continuous pursuit of power density, efficiency, and miniaturization poses significant challenges to the heat dissipation and temperature-rise control of permanent magnet synchronous motor (PMSM) for new energy vehicles. This paper proposes a novel S-shaped axial return passage in the motor casing and a combined oil-cooling scheme integrating S-shaped and end-spraying passages. The geometric structure and parameters of the S-shaped passage and end-spraying passage were designed and optimized, and a finite-element temperature-field model of a PMSM equipped with the combined oil-cooling system is established. The results show that, compared with a traditional right-angle axial returning passage, the pressure loss of the new S-shaped returning passage is reduced by 50%, while the wall heat transfer coefficient remains comparable. At a cooling oil flow rate of 12 L/min, the highest temperature of the end winding is 92.6 °C, only 1.5 °C higher than that of the stator core under rated operating conditions. An experimental prototype was fabricated, and the measured results indicate that the simulated end-winding temperature shows close agreement with the experimental values, with a maximum deviation of only 3.8 °C. The proposed combined oil-cooling scheme efficiently enhances the cooling of both the stator core and end winding and significantly improves the temperature uniformity of the PMSM. Full article

Perseus A (3C 84), a powerful radio source located at the centre of the giant elliptical galaxy NGC 1275—classified as a Seyfert type II AGN and the dominant member of the X-ray bright Abell 426 cluster–exhibits radio emission variability over a wide range of timescales, from decades to hours. This study investigates intraday variability (IDV) in the 6.5 GHz radio emission of 3C 84 using the RT-32 radio telescope in Zolochiv, Ukraine. A novel low-amplitude azimuthal scanning method enabled quasi-simultaneous measurements of antenna and system temperatures, allowing for separation of intrinsic source variations from propagation effects. During an observation session in August 2021, a burst with a peak intensity of 13.5 Jy above the background was detected, likely corresponding to a Fast Radio Burst (FRB). Additionally, quasi-periodic low-amplitude variations with timescales from 0.3 to 6 h were observed. These fluctuations correlate strongly with local atmospheric changes, such as dew formation on the telescope structure, and, to a lesser extent, with ionospheric acoustic–gravity waves. The findings highlight the importance of accounting for propagation conditions when interpreting short-timescale radio variability in AGNs and suggest the need for multi-station, multi-frequency monitoring campaigns to distinguish between intrinsic and environmental modulation of AGN flux densities. Full article

This study presents the design of a high-efficiency pulse width modulation (PWM) power amplifier for marine biological sound reproduction. Due to the capacitive nature of underwater transducers and step-up transformers, output LC filter design is constrained, making it difficult to achieve a flat frequency response and low total harmonic distortion (THD). To address this, the electrical characteristics of these components were measured and modeled to construct equivalent circuits for the PSPICE simulator. Based on these models, an optimized LC filter was designed, and its performance was validated through simulation and experiments. The cause of THD occurring in specific frequency bands was analyzed, and two types of notch filters were applied to improve THD and switching signal attenuation. The proposed methodology offers a practical approach to improving PWM amplifier performance in underwater acoustic systems, supporting the development of compact, efficient, and reliable SONAR transmitters. Full article

Carbon Capture, Utilization and Storage (CCUS) is a critical area of research due to its potential to significantly reduce CO₂ emissions from industrial processes and fossil fuel-based power generation. Aqueous amine solutions are commonly used as chemical solvents for CO₂ capture. However, their application is disfavoured by the high energy requirements and related operational costs, toxicity, and corrosion issues. To address these limitations, research is in general focused on developing novel solvents that can overcome the drawbacks of traditional amines. This development needs the study of phase equilibria in systems for which detailed physicochemical data are often scarce in the literature. In particular, understanding the solubility of gases (CO₂) in possible solvent mixtures is essential for evaluating their suitability for chemical or physical absorption processes. In this work, a dedicated setup was installed to generate the experimental data for these novel systems. This unit was designed to measure the solubility and diffusivity of gases in low-volatility liquids that could be alternative CO₂ solvents. A detailed experimental procedure was established, and the unit was initially validated by measuring CO₂ solubility in a 30 wt% monoethanolamine (MEA) solution, one of the most widely used industrial solvents. The experiments were conducted under conditions representing both the absorption and the regeneration sections of a CO₂ removal plant. The resulting equilibrium data were analyzed by employing several thermodynamic models, and the model providing the best representation was selected. Full article

Traditional scholarship on early Chinese political geography has largely privileged textual analysis, often lacking quantifiable baselines for assessing spatial structure. Addressing this gap, this study utilizes the Shang-Zhou period Shandong region as a focal case to propose a replicable GIS framework—incorporating Kernel Density Analysis (KDA) and Voronoi diagrams—grounded in a null-hypothesis approach. Rather than attempting to simulate theoretical territories, these methods are employed to establish a purely geometric baseline for political space. Central to this study’s findings is the quantification of deviations from this geometric ideal. These measurable discrepancies—manifesting as “Voronoi voids” in mountainous zones and “scale violations” by major powers—serve as empirical indicators for interpreting the tangible impacts of topography, power dynamics, and resource allocation, such as the coastal salt fields identified via KDA. Ultimately, this study demonstrates that this deviation analysis framework functions as a vital quantitative complement to traditional institutional history, effectively elucidating the spatial logic and dynamic evolution of ancient political systems. Full article

Acute respiratory distress syndrome (ARDS) causes heterogeneous injury, with normal, unstable, and edematous tissue distributed throughout the lung. Although positive pressure ventilation initially reduced ARDS-related mortality, it became clear that the ventilator can be a double-edged sword and, if set improperly, can worsen outcomes. This uneven pathology makes the lung vulnerable to secondary ventilator-induced lung injury (VILI). In 2000, evidence showed that lowering tidal volume (V_T) and airway pressure significantly reduced mortality in patients with ARDS, suggesting that this reduction led to less overdistension of healthy lung tissue. Including respiratory system compliance (C_RS) in the calculation. It was shown that low driving pressure (ΔP = V_T/C_RS) was more strongly associated with survival than low V_T alone. This idea was further extended into measuring the mechanical power delivered to the respiratory system: MP_rs = RR × ΔV²∙[1/2∙EL_rs + RR∙(1 + I:E)/60∙I:E∙R_aw] + ΔV∙PEEP, where EL_rs is elastance, I:E is inspiratory:expiratory ratio, R_aw is airway resistance, and RR is respiratory rate. This measure helps identify when the lung is at risk of VILI. However, a recent study found no direct causal link between MP_RS and mortality; rather, it showed that MP_RS, normalized to C_RS or end-expiratory lung volume (EELV), was independently associated with outcomes. This indicates that lung size and underlying pathophysiology—rather than ΔP or MP_RS alone—are critical determinants of VILI risk. Reopening collapsed lung tissue would increase C_RS and decrease E_RS, thereby lowering ΔP or MP_RS at any given V_T, R_aw, PEEP, I:E, or RR setting. Consequently, the focus should shift from simply adjusting the ventilator to normalize C_RS and EELV that reduce ΔP or MP_RS at higher ventilator settings. Full article

Railways play a pivotal role in advancing environmentally conscious and safe transportation systems, positioning them as a vital component of Europe’s future mobility strategy. This study tackles the complex dimensions of sustainability in railway transport by combining environmental impacts and safety considerations within a single, integrated analytical framework. We extend the variable intermediate slack-based measure (VSBM) model to incorporate undesirable outputs—specifically accidents and emissions—allowing for a joint evaluation of safety and environmental performance. The revised model is applied to assess the operational efficiency of 14 European railway operators between 2010 and 2018. Compared to conventional efficiency models, our enhanced VSBM approach provides improved discriminatory power and reveals significant changes in relative efficiency rankings. By integrating safety and environmental dimensions, this study contributes a new perspective on sustainable railway performance measurement. Full article