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Electric faults in photovoltaic (PV) systems cause negative economic and safety impacts, reducing their performance and causing unwanted electric connections that can be dangerous for the user. Line to line, ground and open circuit faults, are three of the main faults that happen in a photovoltaic array system. This work proposes a characterization of the equivalent circuits and the voltage-power (VP) curves at the output of multiple PV arrays under different topological configurations and fault conditions to evaluate the effects of these three main faults on the performance of a photovoltaic array system, taking into account the temperature and solar radiation influence. This work presents a validation of the characterization by measuring the output VP curves of a low-power photovoltaic array system under real outdoors conditions. This method can be useful in future works to develop low cost systems capable of detecting and classifying electric faults in photovoltaic array systems.

Electric faults in photovoltaic (PV) systems cause negative economic and safety impacts, reducing their performance and making unwanted electric connections that can be dangerous for the user. Line-to-line, ground and open circuit faults, are three of the main faults that happen in a photovoltaic array system. This work proposes a characterization of the equivalent circuits and the voltage-power (VP) curves at the output of multiple PV arrays under different topological configurations and fault conditions to evaluate the effects of these three main faults on the performance of a photovoltaic array system, taking into account the influence of temperature and solar radiation. This work presents a validation of the characterization by measuring the output VP curves of a low-power photovoltaic array system under real outdoor conditions. This method can be useful in future works to develop low cost systems capable of detecting and classifying electric faults in photovoltaic array systems Las fallas eléctricas en sistemas fotovoltaicos causan impactos negativos en la economía y la seguridad, reduciendo el desempeño del sistema y generando conexiones eléctricas indeseadas que pueden ser peligrosas para el usuario. Las fallas de línea a línea, conexión a tierra y circuito abierto, son algunas de las principales fallas eléctricas que se pueden presentar en un arreglo fotovoltaico. Este artículo propone una caracterización de los efectos que generan las tres fallas mencionadas en el desempeño del sistema fotovoltaico por medio de un análisis de los circuitos equivalentes y las curvas de voltaje-potencia (VP) que se obtienen frente a diferentes fallas, topologías en el arreglo, condiciones de temperatura y radiación solar. El método propuesto fue validado experimentalmente usando arreglos fotovoltaicos en condiciones reales y puede ser aplicado en trabajos futuros para desarrollar un algoritmo capaz de detectar y clasificar fallas eléctricas en arreglos fotovoltaicos

SnS is one of the most promising layered chalcogenide materials for thermoelectric applications. Novel SnS/Graphite composites were prepared by the one-pot hydrothermal technique to improve the electrical transport properties. Grain boundary scattering and stacking faults introduced by the synthesis method resulted in reduced thermal conductivity of SnS to 0.247 W/mK at 643 K . However, the inclusion of graphite enhanced the crystallinity and carrier concentration by three orders from 4.34 × 10 15  cm −3 to 2.06 × 10 18  cm −3 at room temperature, resulting in increased electrical conductivity from 16.25 S/m in pristine to 432.80 S/m for SnS/G (wt 10%) sample at 643 K. An improved power factor value of 6.63 µW/mK 2 was observed for SnS (1 wt%) sample with enhanced electrical conductivity. Graphical abstract

M50 steel is a commonly used material for aero-engine main shaft bearings. An efficient surface strengthening method, ultrasonic shot peening (USP) technology, was applied to fabricate a gradient nanostructured M50 bearing steel. Coarse and irregular carbides are the main failure source of M50 bearing steel in the subsurface during rolling contact fatigue (RCF). Here, through scanning electron microscopy (SEM) and transmission electron microscopy (TEM), we found that the athermal effects of electrical pulses lead to the decomposition of MC carbides in gradient M50 steel. The results revealed that electric pulse treatment (EPT) resulted in the formation of stacking faults (SFs), helical dislocations, and rotated structures in the MC carbides. High-density non-equilibrium grain boundaries/dislocation walls induced by USP increased the action frequency of the electrical pulses. Additionally, the athermal effects of the electric pulses enhanced the elemental diffusion efficiencies. Concurrently, the stacking faults and helical dislocations also served as diffusion channels and facilitated the diffusion of the alloy elements. These observed stacking faults, helical dislocations, and rotated structures in MC carbide have enriched our comprehension of the decomposition mechanisms in spherical carbides of M50 bearing steel. Decomposition of irregular spherical carbides evolves into rounder spherical carbides is beneficial for both wear resistance and RCF performance.

In a heavily-subjected-to-failure field of rotating machinery, the need for accurate and reliable detection methods is paramount. This paper aims to advance fault detection capabilities through a novel approach that integrates current–temperature–vibration data fusion analysis and also by employing a Random Forest (RF) artificial intelligence methodology. An experimental investigation was conducted to acquire temperature variations, vibration signals, and electrical current readings from a rotating machine subjected to various types of faults. These faults include conditions of normal operation, bearing faults (inner and outer races), shaft misalignment, and rotor unbalance, all monitored under a constant rotating speed of 680 RPM and zero load. Four ceramic shear ICP-based accelerometers, two thermocouples, and three current transformers, were collectively used to collect the data while adhering to the International Organization for Standardization (ISO) standards. To refine the data for the RF algorithm, the standard deviation of the three datasets was calculated at specific intervals, revealing a significant enhancement in diagnostic accuracy when combinedly used. The resulted accuracies varied as follows: 45.0% accuracy using current data alone, 19.4% with temperature data, 62.0% with vibration data, and a remarkable 96.0% when using data fusion. Thus, data fusion is promising in thermal, electrical, and mechanical condition monitoring. Integrating diagnostic approaches in control systems can significantly improve the reliability of rotating machinery.

T-type three-level inverters (T23LIs) are widely used in the electric drive system of new energy vehicles. However, the open-circuit (OC) faults of their switching devices will cause serious damage to the entire system operation. To mitigate the impact of switching faults, this paper proposes an OC fault diagnosis method based on the variations of common-mode voltage in small sectors of T23LI. Firstly, the normal characteristics of T23LI under SVPWM control algorithm are analyzed, and the correspondence between the space voltage vectors and the values of common-mode voltage is established. Then, the common-mode voltage variations under fault conditions are analyzed, and a fault diagnosis method based on these variations is proposed. The faults of the four switching devices in one phase is divided into two groups through the qualitative analysis of common-mode voltage variations, and the specific location of the faulty switch is located by further quantitative analysis. Finally, by analyzing the changes in the three-phase bridge output voltages after faults, the accurate location of the faults in the 12 switches of the three phases is located. Simulation and experimental results verify that the proposed method can accurately and quickly diagnose the single-switch OC faults of all switches, and it effectively accelerates the diagnosis speed and reduces costs by only requiring the collection of a single voltage signal.

Ni-based wrought superalloys are a type of superalloy produced through casting-forging processes, and usually their high-temperature performance is strongly influenced by microstructure and deformation mechanism. The typical microstructure of Ni-based wrought superalloys after heat treatments comprises equiaxed grains, numerous annealed twins, carbides within the grain interior and/or at grain boundaries, and spherical γ′ precipitates (typically comprises around 20% of their volume). The common deformation mechanisms in Ni-based wrought superalloys mainly include anti-phase boundary formed by paired dislocations shearing γ′ phase, stacking fault formed by single dislocation shearing γ′ phase, dislocation bypassing γ′ phase (precipitation-strengthened) and dislocation entanglement, dislocation networks (solid solution strengthened). In this paper, the microstructure and deformation mechanism of tensile and creep in Ni-based wrought superalloys for Advanced ultra-supercritical (A-USC) power plants are reviewed, for the two prominent areas of current research, Ni–Fe-based wrought superalloys exhibit superior processability and cost-effectiveness compared to Ni–Co-based wrought superalloys, thereby offering a more advantageous solution.

The Xiannüshan Fault Zone, located in the southwestern part of the Huangling Anticline within the Three Gorges Reservoir area of Hubei Province, is one of the largest and most complex faults in the region. The geological structures of its different segments vary significantly. Previous studies have primarily focused on the northern segment and often relied on single geophysical methods, which are insufficient for detailed characterization of the entire fault zone. Based on existing geological data, field reconnaissance results, and the geological characteristics of different segments of the fault zone, we employed multiple geophysical methods for a varied investigation: shallow seismic reflection in the northern segment; a combination of waterborne seismic exploration and microtremor survey in the middle segment; and high-density resistivity in the southern segment. The integrated approach revealed the spatial extent, fault geometry, and activity characteristics of each segment, confirming that the Xiannüshan Fault Zone is a pre-Quaternary structure dominated by thrusting. The findings provide a critical scientific basis for regional seismic hazard assessment and disaster mitigation planning, while also establishing a technical framework with significant practical application value for detailed fault characterization in geologically complex environments.

This work is a maiden attempt to investigate the role of fluorinated boron nitride nanosheets (f-BNNs) in monitoring electrical properties of transformer oil (TO). Ultrathin (~5 nm) f-BNNs of 100–500 nm width were obtained by exfoliating pristine h-BN using NH4F. The exfoliation resulted in attaching few electronegative fluorine (F) to boron atoms and converted h-BN from insulator to semiconductor. TO nanofluids (NFs) at 0.005 wt. % of f-BNNs showed ~27 % surge in AC breakdown voltage (BDV) (validated by Weibull statistics), high volume resistivity and excellent stability, superior than h-BN nanosheets or BN nanoparticle. The leap in the electrical insulation was explained due to the fluorination assisted reduction in charge relaxation time from 60 ms–30 s in h-BN to 63 μs–0.6 s in f-BNNs, higher degree of streamer charge scavenging in the electrical double layers (EDLs) and interfacial polarization at the large oil-nanofiller interface. A theoretical calculation yielded in a potential depth of 13.8 V and 19.5 V at h-BN and f-BNNs surface, respectively, which implied f-BNNs provided a huge potential barrier and propagation delay to the streamer charges. Finally, the superior stability of f-BNNs in TO with time and temperature was observed from multiple tests and was explained owing to its 2D morphology, lipophilicity, and F induced large natural electrostatic repulsion between the nanosheets. Such excellent responses at low filler fractions recommends f-BNNs as a better alternative among all reported BN brothers for future TO applications.

Poly(p-phenylene benzobisoxazole) (PBO) fibre-based specialty paper has become a promising candidate for high-performance insulating materials due to the remarkable properties of PBO fibres. However, the porous structure and poor interfacial interaction of PBO paper seriously weaken its mechanical strength and greatly limit its practical application. Herein, proposed for the first time, a homogeneous reinforcement strategy is developed to regulate the microstructure of PBO paper and efficiently enhance its overall properties. For this reason, flexible ortho-hydroxy polyamic acid (HPAA) was first synthesized and used to impregnate PBO paper. Subsequently, HPAA was thermally converted into a benzoxazole-containing resin, manifesting excellent interfacial compatibility with PBO paper. As a result, the compact structure and solid interface endow the composite paper with impressive performance. The tensile strength, modulus, and electrical breakdown strength of the composite paper are 116.86 MPa, 5.47 GPa, and 63.7 kV mm−1, respectively, increasing by 33.1, 8.1, and 1.1 times compared with those parameters of the original paper (3.43 MPa, 0.60 GPa, and 30.5 kV mm−1). Moreover, the composite paper also exhibits an ultra-low dielectric constant and loss tangent (1.6 and 0.004 at 106 Hz, respectively), as well as superhigh thermal stability (maximum decomposition temperature, Tmax ≈ 600 °C) due to the elaborate design of the structure. Thus, the mechanical strength has been successfully integrated with the outstanding insulation and thermal properties, rendering the lightweight PBO composite paper promising in the field of high-temperature and high-voltage electrical insulation.