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Objective The MS 6.8 earthquake that struck Luding County, Sichuan Province, on September 5, 2022, and its aftershocks have drawn widespread attention, especially concerning the potential risks of induced seismicity associated with the construction of high-dam reservoirs in regions with high seismic intensity. Previous studies have explored the possible link between reservoirs and seismic activity, without reaching a definitive conclusion. This study aims to assess the impact of water storage in the Dagangshan Reservoir on the surrounding strata and its correlation with recent seismic events. Methods Numerical simulation methods were employed using high-precision digital elevation model (DEM) data, fault data, and reservoir water level information to develop a three-dimensional poroelastic finite element numerical model extending from the surface to a depth of 25 km. By analyzing the hydrogeological conditions, lithology of rock masses, and groundwater dynamic changes, this study evaluated the seismic hazard risk of major faults, such as the Moxi Fault, and calculated variations in Coulomb stress and strata pore pressure at the hypocenter during the occurrence of the earthquake. Results The study indicates that, during the MS 6.8 Luding earthquake on September 5, 2022, the pore pressure at the epicenter reached 5 kPa, and the Coulomb stress increased by 3.6 kPa, suggesting that the impoundment of the Dagangshan Reservoir contributed to an increased risk along the Moxi Fault on the northwestern side of the reservoir. Using the source parameters of the MS 5.6 aftershock that occurred on January 26, 2023, it was observed that the impoundment caused a change in Coulomb stress at the epicenter of -0.69 kPa and a pore pressure of approximately 0.32 kPa. It is evident that the reservoir impoundment had a relatively minor impact on the fault activity where the MS 5.6 aftershock occurred and even exhibited a certain inhibitory effect. Moreover, seismic activity was mainly concentrated in two areas on the western side of the reservoir, with both the seismicity and expected magnitudes in these regions reflecting a higher risk of earthquakes. Conclusion This study demonstrates a correlation between the impoundment activities of the Dagangshan Reservoir and the occurrence of the Luding County earthquake and its aftershocks. The spatial distribution characteristics of the earthquakes align with the geological stress adjustment patterns following the reservoir impoundment, which played a promotive role in the occurrence of the MS 6.8 main shock, leading to an increased risk of earthquakes in the Moxi Fault region. This finding is significant for understanding the mechanisms of reservoir-induced earthquakes, subsequent aftershock analyses, and earthquake disaster prevention and mitigation efforts. Significance The results of this study provide new insights into the complex relationship between reservoir water storage and seismic events. This study offers a scientific basis for future assessments of seismic risks of reservoir design and operation, contributing to improved accuracy in earthquake early warnings and efficiency in disaster prevention and mitigation efforts.

The mechanisms governing electric field and partial discharge (PD) under stress cone dislocation remain unclear. This study employs the finite element method to explore the relationship between the electric field, externally applied voltage, and length of dislocation. Subsequently, the correlation between voltage and electric field is determined. The relationship between voltage and PD is established through PD tests conducted under stress cone dislocation conditions. By considering the influence of voltage, the association between the electric field and PD is established, revealing the mechanism of PD initiation by electric field distortion in joints. The findings suggest that the lifetime and reliability were increased by wrapping semi‐conductive self‐adhesive tape around the exposed cross‐linked polyethylene (XLPE) insulation layer. The electric field at a specific location is approximately proportional to the applied voltage. However, the slope is influenced by the composite insulation interface and the radial distance of the copper conductor. When crossing the interface between the XLPE insulation layer and the accessory insulation layer, the slope decreases significantly. The threshold for electric field PD is determined by examining the electric field distribution and the PD inception voltage during testing. When the voltage is sufficiently high, significant electric field distortions can occur at multiple points in the joint, potentially leading to concurrent PDs at several locations. [ABSTRACT FROM AUTHOR]

Mesoproterozoic (ca. 1.3 Ga) magmatism in the North China Craton (NCC) was dominated by mafic intrusions (dolerite sills) with lesser amounts of granitic magmatism, but our lack of knowledge of this magmatism hinders our understanding of the evolution of the NCC during this period. This study investigated porphyritic granites from the Huade–Kangbao area on the northern margin of the NCC. Zircon dating indicates the porphyritic granites were intruded during the Mesoproterozoic between 1285.4 ± 2.6 and 1278.6 ± 6.1 Ma. The granites have high silica contents (SiO2 = 63.10–73.73 wt.%), exhibit alkali enrichment (total alkalis = 7.71–8.79 wt.%), are peraluminous, and can be classified as weakly peraluminous A2-type granites. The granites have negative Eu anomalies (δEu = 0.14–0.44), enrichments in large-ion lithophile elements (LILEs; e.g., K, Rb, Th, and U), and depletions in high-field-strength elements (HFSEs; e.g., Nb, Ta, and Ti). εHf(t) values range from –6.43 to +2.41, with tDM2 ages of 1905–2462 Ma, suggesting the magmas were derived by partial melting of ancient crustal material. The geochronological and geochemical data, and regional geological features, indicate the Mesoproterozoic porphyritic granites from the northern margin of the NCC formed in an intraplate tectonic setting during continental extension and rifting, which represents the response of the NCC to the break-up of the Columbia supercontinent. [ABSTRACT FROM AUTHOR]

Seafloor spreading is an important cornerstone of the theory of plate tectonics. Asymmetric seafloor spreading and oceanic ridge jumps are common phenomena in this process and play important roles in controlling oceanic crust accretion, regional tectonics and geological geometric boundaries. As the largest marginal sea in the western Pacific, the South China Sea is an ideal laboratory for dissecting the Wilson cycle of small marginal sea-type ocean basins restricted by surrounding blocks and exploring the deep dynamic processes of confined small ocean basins. In recent years, a lot of research has been conducted on the spreading history of the South China Sea and has achieved fruitful results. However, the detailed dynamic mechanisms of asymmetric seafloor spreading and ridge jumps are still unclear. Therefore, this paper summarizes the basic understanding about the dynamic mechanisms of global asymmetric seafloor spreading and ridge jumps and reviews the related research results of asymmetric seafloor spreading and ridge jumps in the South China Sea. Previous studies have basically confirmed that seafloor spreading in the South China Sea started between ~32 and 34 Ma in the east sub-basin and ended at ~15 Ma in the northwest sub-basin, with at least once oceanic ridge jump in the east sub-basin. The current research mainly focuses on the age of the seafloor spreading in the South China Sea and the location, time and stage of the ridge jumps, but there are relatively few studies on high-resolution lithospheric structure across these ridges and the dynamic mechanism of oceanic ridge jumps. Based on the current research progress, we propose that further studies should focus on the lithosphere–asthenosphere scale in the future, suggesting that marine magnetotelluric and Ocean Bottom Seismometer (OBS) surveys should be conducted across the residual oceanic ridges to perform a detailed analysis of the tectonics magmatism in the east sub-basin to gain insights into the dynamic mechanisms of oceanic ridge jumps and asymmetric seafloor spreading, which can promote understanding of the tectonic evolution of the South China Sea and improve the classical plate tectonics theory that was constructed based on the open ocean basins. [ABSTRACT FROM AUTHOR]

Distributed acoustic sensing incorporates multiple indicators, and there exists a mutually constraining relationship among these indicators. Different application fields have varying requirements for indicators. Therefore, indicator testing and comprehensive evaluations are crucial for engineering applications. In this paper, we conducted a theoretical analysis of key indicators, including frequency response, sensitivity, spatial resolution, sensing distance, multi-point perturbation, and temperature influence. The indicator test scheme was developed, and a test system was constructed. The test data were analyzed and compared in the time-frequency domain. A performance evaluation method for distributed acoustic sensing, based on the analytic hierarchy process, is proposed, and a comprehensive evaluation example focused on high-frequency applications is presented. The results show that the test scheme and method presented in this paper can accurately measure the upper limits of each indicator of distributed acoustic sensing. The proposed comprehensive evaluation method enables the assessment of sensor performance and applicability based on engineering practices. It addresses the challenge of evaluating distributed acoustic sensing with multiple indicators and offers an efficient approach for equipment development and engineering applications. [ABSTRACT FROM AUTHOR]

The fault of insulation leakage of distributed photovoltaic power station is always the technical difficulty of photovoltaic power station. Especially in every link from the photovoltaic cell array to the grid-connected inverter, the wiring is complicated and the environment is bad.In view of the disadvantages of traditional monitoring technology, a distributed leakage monitoring system based on power line communication is proposed. The system combines the power line communication technology with the sensor technology. The design and optimization of the hardware and software of the acquisition node and the central monitoring terminal are completed.The data collection and transmission of collecting point leakage current are realized. The system is tested with different temperature conditions.Through experimental verification, the reliability of the system is above 97%, which can effectively monitor the leakage of distributed photovoltaic power station.

Plant landscape is an indispensable part of the city. Regional plant landscape not only has excellent ecological benefits, but also can better show the regional characteristics and human culture of the city. Through the analysis of plant landscape in the industrial city, it is concluded that how to make better use of plants to create urban plant landscape with regional characteristics is the focus of regional plant landscape construction.

In order to clarify the trapping efficiency of different types of sex pheromone traps on populations of Spodoptera litura in soybean fields, three kinds of conventional traps, called YL-VT, YL-HEMT and YL-NMT, and types of traps equipped with a automatic catch monitoring mechanism, called AIM and AIM-lite-A, have been tested. These last two allow monitoring the diurnal and seasonal rhythms of the catches. From 5 August to 5 October 2020, each YL-VT trap caught an average of 84.4 heads of S. litura moths per day, which was significantly higher than the YL-HEMT (11.8 heads), YL-NMT (16.5 heads) and AIM (9.7 heads), which did not show significant differences between them. The half-life of pheromone attraction effect in YL-VT trap is about 17–20 days. Considering the number of trapping and the duration of pheromone attraction effect, YL-VT trap is the best. For efficient monitoring, the validity period is approximately 15 days. Among the causes that could explain its higher capture rate and efficiency, the YL-VT trap has the smallest and largest number of inlet devices, and in it, the lure core is located inside of the insect inlet device. Under different occurrence numbers of S. litura, the accuracy of the automatic count of AIM-lite-A is 90% greater than in the AIM trap. The diurnal rhythms of S. litura observed by AIM-lite-A show that S. litura have two active periods that are from 18:00 to 21:00 and from 23:00 to 4:00 at night and that the first active period may be affected by sunshine and temperature. The annual activity rhythm of S. litura monitored by AIM showed that the activity of S. litura was related to temperature, there were approximately 6 generations of S. litura in a year and that the activity peak was from August to September in Dangtu, China. AIM and AIM-lite-A can be used for the annual monitoring of S. litura population in soybean fields because of their automatic counting function. AIM can simultaneously record a variety of meteorological data, AIM-lite-A has higher accuracy and a lower cost, which can be selected according to different situations. In conventional traps, the trap YL-VT can be used for the population monitoring of S. litura in soybean fields and pest control in the field, especially in greenhouses and net rooms where organic soybeans are grown, due to its low cost and efficient trapping ability. [ABSTRACT FROM AUTHOR]