Search Results (970)

Partial discharge (PD) signals acquired from gas-insulated switchgear (GIS) are often severely contaminated by discrete-spectrum interference and periodic narrowband noise, which impairs the accuracy of subsequent fault diagnosis. This paper proposes a hybrid denoising method that integrates Spearman coefficient-optimized variational mode decomposition (S_VMD), spatially related recursive sample entropy (Sdr_SampEn) for intrinsic mode function (IMF) classification, an improved wavelet threshold function, and Savitzky–Golay (SG) filtering. First, the Spearman correlation coefficient between the original signal and the reconstructed signal is used to adaptively determine the optimal mode number K of VMD, avoiding the over- and under-decomposition problems of conventional VMD. Second, Sdr_SampEn, which characterizes signal irregularity along both the Chebyshev distance and spatial direction of a recurrence plot, is employed to classify the obtained IMFs into noise-dominant and PD-dominant components, with the discrimination threshold calibrated as p = 1.94 at 0 dB. Third, an improved wavelet threshold function—continuous at the threshold and asymptotically unbiased—is applied to the noise-dominant components, while SG filtering is applied to the PD-dominant components, after which the denoised signal is reconstructed. The results demonstrate that the proposed method effectively suppresses both white and narrowband noise while preserving the detailed morphology of PD pulses. Full article

High-nickel NCA/Si–C 21700 cells exhibit strongly condition-dependent degradation, but the coupled influence of temperature and rate on electrochemical, thermal, and structural evolution remains insufficiently resolved. Here, Samsung INR21700-50E cells were aged under a 3 × 3 matrix of ambient temperatures (0, 23, and 40 °C) and C-rates (0.5C, 1C, and 2C). Periodic reference performance tests were used to track capacity, 10 s direct-current internal resistance, electrochemical impedance, pseudo-open-circuit voltage, differential voltage/incremental capacity behavior, heat generation, and post-mortem morphology. Guided by the hypothesis that temperature and rate history change not only the speed but also the dominant pathway of aging, the results show that both ambient temperature and the charge/discharge rate program govern the aging trajectory. Low-temperature cycling accelerates capacity loss and resistance growth through severe polarization and lithium plating, indicating dominant loss of lithium inventory. High-temperature operation promotes interfacial side reactions, impedance rise, and cathode structural degradation, leading to stronger loss of active material at later stages. An increasing C-rate amplifies these effects by raising overpotential and thermal load. Heat generation power increases markedly with aging and depends strongly on temperature–rate history. Scanning electron microscopy confirms cathode cracking, anode surface film thickening, and separator degradation under severe conditions. These experimental indicators are integrated into a mechanism-aware diagnostic framework that maps capacity retention, DCIR/EIS parameters, ICA/DVA indices, and heat generation metrics to dominant aging modes, supporting BMS state-of-health estimation, lifetime prediction, thermal management, and second-life screening of high-nickel NCA cells. The condition-averaged trajectories are further converted into a semi-empirical aging law that links capacity loss, resistance growth, and heat generation increase for BMS-oriented lifetime prediction. Full article

This study proposes a multi-objective optimization strategy for the structural design of liquid-cooled channels in battery systems, aiming to identify liquid-cooled plate design schemes with better cooling performance and acceptable flow resistance. Optimal Latin hypercube sampling (OLHS) was combined with computational fluid dynamics (CFD) simulations to construct a CFD-generated dataset that includes the maximum temperature and system pressure drop. Then, modeFRONTIER was employed to integrate surrogate-model training, rapid prediction, and non-dominated sorting genetic algorithm II (NSGA-II) optimization, thereby obtaining the Pareto optimal set. The technique for order preference by similarity to ideal solution (TOPSIS) decision method was further introduced to determine the final optimal design. Results indicate that the optimized liquid-cooling system exhibits outstanding comprehensive performance in terms of balancing heat dissipation and flow resistance at a 5 C discharge rate. Remarkably, sensitivity analysis shows that inlet velocity is the dominant factor affecting the maximum battery temperature, with a correlation coefficient of −0.789. The maximum temperature of the battery module is effectively limited to 30.07 °C, while the flow pressure drop is only 799.58 Pa, achieving an excellent balance between heat dissipation efficiency and energy consumption. Full article

Concentrated rear runoff is an important hydraulic factor that promotes slope instability and flow-like transport characteristics in mountainous landslides; however, the deformation–failure process of slopes and their response relationships under different runoff intensities remain unclear. In this study, the Shaziba landslide in Enshi, Hubei Province, China, was selected as the research object. Two-dimensional flume model tests were conducted under four runoff discharge conditions of 7, 15, 27, and 35 mL/s to investigate the effects of runoff intensity on the hydraulic response and failure mode of the slope. The results show that, as the runoff discharge increased from 7 to 35 mL/s, the initial response times of water content, pore water pressure, and earth pressure at the rear edge decreased from 1205, 1488, and 888 s to 160, 248, and 112 s, respectively. Meanwhile, the gully formation time shortened from 6810 to 336 s, and the time of the first evident collapse decreased from 5758 to 650 s. Under low-runoff conditions, slope deformation was dominated by infiltration-induced softening and progressive creep. Under moderate to high runoff conditions, gully incision and gully-wall collapse accelerated slope disintegration, resulting in soil–water mixed transport and enhanced mobility of failed materials. Concentrated rear runoff drives the slope through successive stages of initial deformation, structural disintegration of the slope, flow-like failure, and toe deposition. These findings provide experimental evidence for the identification and prevention of landslides controlled by rear runoff. Full article

The increasing adoption of electric vehicles (EVs) demands highly efficient bidirectional DC–DC converters capable of seamless energy transfer between the grid and vehicle batteries. This paper introduces a Fixed-Frequency Dual-Active-Bridge (DAB) resonant converter featuring four degrees of freedom, achieved through a combination of triple phase-shift (TPS) modulation and a current-controlled variable inductor (VI). The proposed control strategy aims to minimize conduction and switching losses by simultaneously managing reactive power, RMS current, and soft-switching conditions across wide variations in voltage and power. Unlike conventional phase-shift or variable-frequency modulations, the fixed-frequency operation maintains full zero-voltage switching (ZVS) for the two bridges, and zero-current switching (ZCS) in the bridge that is receiving energy, enhancing overall system reliability and control simplicity. The proposed converter is validated through simulations and experimental results from a SiC MOSFET-based 14 kW prototype operating at 122 kHz, demonstrating peak efficiencies above 97% under both charging and discharging modes. The experimental results confirm that the proposed DAB topology and modulation scheme significantly improve efficiency and controllability, making it a promising solution for next-generation on-board chargers and vehicle-to-grid (V2G) applications. Full article

Transformer oil is a critical insulating medium in high-voltage equipment, and its discharge characteristics under high electric fields significantly limit overall performance. Current negative streamer classification methods rely primarily on propagation velocity, failing to effectively explain the underlying transition rules and mechanisms. To address this, we developed an impulse discharge experimental platform featuring a shadowgraph optical diagnostic system. By analyzing the morphological evolution, current pulses, and light emission signals of negative streamers across various voltage levels and liquid pressures, this study elucidates their transition mechanisms and mode classifications. The results demonstrate that negative streamer discharge initiates in a primary subsonic mode with a thin-rod channel. It then evolves into either a heavily branched, thick-channeled secondary mode (bush-like) or a faster, less-branched tertiary mode. Under sufficiently high overvoltage, it transitions to a supersonic quaternary mode with filamentary channels. Notably, negative streamer development exhibits distinct gaseous characteristics, and the channel deformation process aligns with the Rayleigh theory of bubble dynamics in liquids. Finally, appropriately increasing liquid pressure compresses the streamer channel, facilitating the transition from the secondary to the tertiary mode. Full article

This work presents the realization of a compact and embedded impedance-based sensor system for the characterization of lithium-ion batteries by means of electrical impedance spectroscopy (EIS). The analog magnitude-ratio and phase-difference detection (MRPDD) method is implemented and extended through a generalized formulation that models the shunt element as a frequency-dependent impedance and compensates the parasitic contributions of the printed circuit board. This reformulation corrects magnitude and phase errors introduced by the measurement hardware without increasing the overall complexity. The prototype comprises two main functional blocks: current-mode excitation and voltage-mode measurement. The excitation stage uses an operational transconductance amplifier and a power MOSFET to generate a voltage-controlled current source, whereas the sinusoidal voltage signal is generated by means of a direct digital synthesizer. The measurement chain relies on differential acquisition using instrumentation amplifiers and analog magnitude/phase detection based on the AD8302 vector detector under microcontroller control. The proposed method has been first validated by simulations using both a linear RC equivalent model and an extended Randles-type battery-equivalent model, and then experimentally characterized using a linear RC equivalent model of the device under test. Measurements show that the generalized formulation recovers the ideal impedance response in the presence of parasitic effects, both in the shunt device and in the printed circuit board. In the experimental validation with the RC model, a magnitude error of 1.65% is obtained at 1 kHz, which is adopted as the upper frequency limit for battery characterization, even though operation up to 10 kHz is possible. Phase measurements revealed that the input capacitive coupling of the vector detector, conceived for operation in the RF range, requires an adaptation for appropriate operation in the intended frequency range. The prototype has been also applied to the characterization of a commercial lithium-ion 18650 cell, enabling the measurement of battery impedance and the analysis of its dependence on the state-of-charge and on the discharge current. Full article

Conventional maize fertilization suffers from uneven distribution, fertilizer waste, and environmental pollution. To address these issues and achieve precision fertilization for maize, a straight grooved-wheel fertilizer apparatus (SGWFA) was designed and optimized using the discrete element method (DEM). The blocking characteristic of the SGWFA was also evaluated. The optimal configuration (eight grooves, inner diameter of 26 mm) yielded a minimum discharge uniformity coefficient of variation of 2.50% and mild blocking, with a maximum total force of 161.884 N. Furthermore, a nonsingular terminal sliding mode control (NTSMC) algorithm was proposed for the speed loop of the brushless DC (BLDC) motor drive, while the current loop used conventional proportional-integral (PI) control. The overall system achieved dual closed-loop speed and current regulation with finite-time convergence of the speed tracking error. Simulations showed that, compared with conventional PI and fuzzy PI controllers, NTSMC had the smallest overshoot of 3.4%, the shortest settling time of 0.165 s, and the fastest disturbance rejection. Bench tests confirmed that the coefficient of variation under NTSMC was 2.85%, markedly better than fuzzy PI’s 3.15% and conventional PI’s 4.03%. It is also basically consistent with the simulation results. Field tests at 6, 9, and 12 km/h demonstrated over 95% per-row fertilization accuracy, with a maximum relative error of only 4.61%. This integrated system can effectively achieve precise fertilizer application under variable field conditions. Full article

Plasma-pulse water treatment using a high-voltage underwater spark discharge is a reagent-free approach with potential for simultaneous disinfection and physicochemical modification of water. In this study, a laboratory-scale recirculating reactor (Vtot = 10 L) equipped with a storage capacitor of C = 0.25 μF was operated at U = 15–30 kV and a pulse repetition frequency of about 1.8 Hz to evaluate disinfection performance and system-level energy characteristics for two water matrices, surface wastewater and tap water. The corresponding calculated capacitor-stored energy ranged from 28.1 to 112.5 J per pulse. Microbiological and physicochemical measurements were performed in triplicate. At U = 30 kV, the total microbial count in wastewater decreased from approximately 1 × 10⁵ CFU/mL to below the method detection limit (LOD = 1 CFU/mL) within 2–3 min. For the 2 min/10 L operating mode, the system-level specific energy input was estimated at 6.7 kWh/m³. During the initial treatment period, temperature-compensated conductivity (σ25) decreased by 3–8%, depending on the water matrix, and then increased with prolonged treatment. These results show that the tested reactor can provide rapid reagent-free reduction in culturable microflora under the studied conditions. However, plasma-pulse treatment should be regarded primarily as an advanced treatment, polishing, or pre-treatment option for complex water matrices rather than as a universal replacement for conventional large-volume disinfection technologies. Full article

The desire to use space in the most rational and efficient way to address contemporary challenges leads to the necessity of creating multi-purpose space missions capable of solving a wide range of diverse tasks. This creates a demand for propulsion systems that can provide high maneuverability for modern and future spacecraft. One potential solution to increase the maneuverability of satellites is the use of electrodeless plasma thrusters with magnetic thrust-vectoring (MTVEPT). Their simple design and acceptable thrust-to-power characteristics can improve the cost-effectiveness of a space mission, increase its reliability and operational lifetime, and enable the required orbital maneuvers. This paper presents an experimental study on the ignition thresholds of a radiofrequency discharge in an electrodeless plasma thruster utilizing argon. The study is conducted over a gas flow rate range of 20 to 210 sccm, with solenoid currents from 0 to 5 A, for two magnetic field directions and two diameters of the exhaust orifice, which is varied using a diaphragm. It is found that a 93% relative reduction in the channel diameter leads to an average twofold decrease in the discharge ignition threshold, reaching a minimum value of 2.5 × 10³ V/m at a flow rate of 100 sccm. This can be used to reduce the thruster’s power consumption for the repetitive discharge ignitions when the propellant reserves are limited. Furthermore, four distinct discharge ignition regions are identified, depending on the solenoid current. The existence of a minimum threshold electric field for the discharge ignition of 4.0 × 10³ V/m is demonstrated for a multidirectional electrodeless plasma thruster without changing the discharge channel geometry within the studied parameter range, occurring at a solenoid current of I = 2 A. Full article

High-voltage short pulse generators play a critical role in medical and industrial applications. However, the presence of residual stored energy can pose significant electrical safety hazards. To mitigate these hazards, the implementation of rapid discharge mechanisms is imperative. To address the limitations of slow passive bleeders and auxiliary-dependent active circuits, and the issue of excessive size for compact pulse generators, this study proposes a self-powered, fast-response discharge topology utilizing cascaded depletion-mode NMOS transistors. The method utilizes the inherent normally-on characteristic of depletion-mode devices to ensure fail-safe activation during power loss, employing a self-biased feedback loop to regulate a constant discharge current. The theoretical models were validated through simulations and a hardware prototype testing a 1200 V/220 nF capacitor. The experimental results demonstrate the capability to successfully discharge 1200 V to a safe level within a span of one second. Additionally, the discharge time can be programmed within the range from 72 milliseconds to 1.02 s by adjusting the current-limiting resistor. In summary, the proposed topology offers a reliable, compact, and adjustable solution for high-voltage safety, addressing the limitations of conventional discharge technologies in terms of volume and speed. Full article

Decomposition of nonlinear, nonstationary multicomponent signals remains challenging for existing decomposition strategies, including frequency-based, data-driven, and subspace methods, which can suffer from mode mixing, leakage across components, and unreliable isolation of transients. Motivated by this gap, this study proposes Orthogonal Self-Similarity Decomposition (OSSD), which exploits a self-similarity structure in delay-embedded orbit geometry so that temporal organization, rather than spectrum alone, guides component construction. OSSD-Basic introduces three algorithmic novelties within a single pipeline: (1) an adaptive proxy-correlation band merging on the delay axis, (2) a dominant-component cascade that prevents energy-dominant carriers from masking weaker components, and (3) a double MGS + LS reprojection that collapses the inter-mode orthogonality index to numerical zero, regardless of merging and pruning operations. Synthetic experiments with known ground truth show that OSSD-Basic provides a parsimonious four-mode representation with exact inter-mode orthogonality (OI = 9.4 × 10⁻¹⁸), the highest reconstruction SNR among the evaluated baselines (27.14 dB), and the highest ground-truth diagonal correlation sum (3.038) among the tested methods, while using two fewer modes than EMD, VMD, and SSA. Daily streamflow forecasting on a U.S. Geological Survey discharge record further shows that augmenting OSSD-derived inputs with fractal descriptors and fractional-order differencing features yields progressive accuracy gains over the AR-ANN baseline, with R² improving from 0.855 to 0.915 at one-step-ahead and from 0.388 to 0.699 at four-step-ahead forecasting in the single-input setting, within a single-station case study on USGS 01554000. Overall, OSSD-Basic offers an interpretable multiscale decomposition with guaranteed inter-mode orthogonality and a structured feature pathway for oscillatory–transient mixtures. Full article

As agriculture moves towards green transformation and low-carbon production, the high energy consumption, environmental burden, and residue risks associated with conventional chemical fertilisers, pesticides, and disinfectants have become increasingly prominent. Non-thermal plasma (NTP) can generate reactive oxygen and nitrogen species (RONS) under near-ambient temperature and pressure conditions, while offering low chemical residue, high reactivity, and modular equipment design. It has therefore attracted growing attention in agricultural engineering and green agricultural input preparation. This review focuses primarily on studies published within the past five years, together with the selected foundational literature retrieved from Web of Science, Scopus, PubMed, MDPI, and ScienceDirect. It systematically examines the fundamental mechanisms, application modes, and representative agricultural scenarios of NTP, with particular emphasis on agricultural nitrogen fixation and fertilisation, seed treatment and seedling raising, crop growth regulation and protection, soil improvement and remediation, and postharvest preservation and safety treatment of agricultural products. Key technological advances are then summarised, including optimisation of discharge systems and reactor configurations, plasma–catalysis synergy, preparation of plasma-activated water (PAW) and plasma-activated mist (PAM), and the development and integration of specialised agricultural equipment. In addition, the current state-of-the-art (SOA) of artificial intelligence (AI) applications in plasma-process modelling, process-parameter optimisation, agricultural performance evaluation, and intelligent control is discussed. Existing evidence indicates that NTP is particularly relevant to controlled-environment agriculture, including greenhouse cultivation, hydroponics, and aeroponics, where discharge processes, water or nutrient solutions, and crop root-zone management can be coupled for in situ nitrogen supply, activated-medium preparation, and crop protection. However, reported effects remain strongly dependent on discharge type, energy input, reactive-species composition, treatment dose, crop species, cultivation system, and application route. Therefore, NTP-based agricultural technologies should be evaluated using consistent indicators, including energy consumption, product selectivity, reactive-species stability, treatment throughput, crop response, ecological safety, and system-level integration with AI and IoT. Future research should prioritise high-efficiency reactors, standardised evaluation frameworks, cross-scale mechanistic understanding, reliable datasets, and closed-loop intelligent control, thereby supporting the transition from laboratory studies to reproducible and application-oriented agricultural systems. Full article

To investigate the dynamic characteristics of key parameters in a piston gravity energy-storage system, an experimental system for novel piston gravity energy storage is designed and developed. Firstly, the structure and working principle of the piston gravity energy-storage system are analyzed. Adopting a modular modeling approach, the system is divided into four core modules, and the piston motion, vertical cylinder chamber pressure, hydraulic actuator, and turbine power models are established. Subsequently, a case study simulation is conducted on the piston gravity energy-storage system to model its dynamic characteristics during discharge conditions, analyzing the variation patterns of key parameters such as the chamber pressure, flow rate, and output power within the system. Finally, the experimental system integrates a digital controller with proportional–integral power regulation and an automatic mode switching logic to enable the constant power closed-loop control, with real-time acquisition of the chamber height, pressure, flow rate, and electrical parameters. The dynamic responses of various system parameters are analyzed. Experimental results indicate that under constant power charging and discharging conditions, the height of the upper chamber exhibits a linear trend, the pressure in the lower chamber is inversely proportional to the height of the upper chamber, and the flow rate remains stable with charging and discharging power. Neglecting energy losses of the pump and hydraulic turbine and only considering friction and hydraulic losses, the charge–discharge efficiency of the energy-storage experimental system is 65%. Full article

Comprehensive mechanized solid backfilling technology exhibits significant advantages in solid waste disposal, “three-under” coal mining, and dynamic disaster control. However, its large-scale application is constrained by low production efficiency, high unit production cost, and high labor intensity. Therefore, industrial upgrading through intelligent technologies is urgently required. In this study, methods including literature review, theoretical analysis, and field measurements are employed to propose three backfilling modes. The configurations of the six core subsystems under each mode are systematically summarized, and the core definition of an intelligent backfilling mine is established. Furthermore, a key technology framework for intelligent backfill mining is developed, based on PLC control and PID algorithms, with a closed-loop architecture centered on “perception–decision–execution.” Engineering applications demonstrate that the surface gangue intelligent pretreatment system achieves functions including automatic vehicle washing, intelligent dust suppression spraying at discharge points, dynamic metering during conveying, and adaptive adjustment of feeding systems. The intelligent surface-to-underground coal gangue vertical feeding system enables full silo alarm and level regulation. The underground jigging intelligent separation system realizes intelligent jigging ratio adjustment, intelligent bed layer measurement and control, and intelligent air volume regulation, with the coal content in gangue discharge maintained below 4%. At the working face, the intelligent solid backfilling system doubles monthly coal output, boosts backfilling efficiency by 50%, and cuts the workforce by 8–10 workers. The intelligent backfilling effectiveness monitoring system operates stably, with a working face weighting factor of 1.12 and precise ground deformation control within Grade I limits. Full article