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The online core monitoring system (CMS) is a crucial system for ensuring the safe operation of nuclear power plants. Its primary function is to real-time monitor the key parameter changes within the reactor core, in order to timely detect potential abnormal conditions and provide subsequent operational recommendations. The mathematical modeling of the main functions of online CMS was conducted, and its core modeling forward problem was clearly defined as well as the inverse problems of monitoring, diagnosis, and operational control. Through analyzing the research status of typical online CMS systems, the solution approaches for the aforementioned forward and inverse problems were identified, providing references for resolving specific engineering issues of online CMS in the future. The reactor core modeling mainly involves high and low-fidelity mechanistic models, as well as various machine learning models and model order reduction techniques. Solving the detector placement, physical field reconstruction, and uncertainty quantification problems using diverse types of detectors and data assimilation algorithms is the core of the monitoring inverse problem. The diagnosis inverse problem primarily relies on in-core and ex-core neutron detector information to analyze the causes of control rod drop, self-powered neutron detector anomalies, and vibration abnormalities. Utilizing the theoretical models of core tracking, various types of reactivity or power distribution control constitute the main tasks of the operational support inverse problem. Furthermore, this paper points out the existing issues in current online CMS technology research, such as multi-source information fusion, uncertainty quantification, and operational procedures. Particularly, considering the influence of various uncertainty factors within the framework of digital twins and numerical reactors, to enhance the plant operating capability, is one of the future development directions for online CMS and its underlying technologies.

China is currently facing a critical period of economic transformation and social development, with land use being under tremendous pressure, facing multiple challenges. The imbalance in land use structure is becoming increasingly prominent and conflicts over various land uses are becoming more intense, thereby attracting an increasing focus. Land use conflict refers to the inconsistent and disharmonious land use methods and quantities among stakeholders in the process of land resource utilization, as well as the conflicting states between various land use methods and environmental aspects. The study of land use conflicts can provide important references for stabilizing land use structures, alleviating land use conflicts, and optimizing the allocation of national spatial resources. Identifying the spatial range and intensity of land use conflicts is a prerequisite for alleviating regional land use pressure. However, existing research has thus far provided insufficient characterization of the negative ecological and environmental effects of land use. The concept of ecosystem service trade-offs is advantageous regarding expressing the negative effects of land use conflicts and their inherent causes. Therefore, based on the perspective of ecosystem services, this study identifies the intensity and spatial distribution characteristics of land use conflicts in the Guangdong-Hong Kong-Macao Greater Bay Area in different types of space using ecosystem service trade-off analysis. Results show that from 2010 to 2020, land use change in the Guangdong-Hong Kong-Macao Greater Bay Area was relatively drastic, with a decrease of 1,440.90 km2 (8.20%) in arable land area and an increase of 1,649.92 km2 (28.01%) in urban land area. During the study period, carbon fixation, soil retention, and water production services exhibited increasing trends, whereas food supply and habitat quality services exhibited decreasing trends. High-gain areas of food supply and carbon fixation, as well as high-loss areas of water production and soil retention, were mainly distributed in the southwest and northwest of the study area. The land use conflict index of the study area was 1.05, indicative of strong land use conflict. This was mainly because the study area had a large number of service types to balance, with the balance relationships being strong. Among them, the balance relationships between water production and food supply, habitat quality, and carbon fixation were the dominant factors in land use conflicts in the study area. The intensity of land use conflicts in each subregion ranged from strong to weak in the following order: natural or semi-natural area (1.10) > semi-natural semi-artificial area (0.97) > artificial area (0.77) > semi-natural area (0.45). Natural or semi-natural area was the main area of land use conflicts, mainly because this area had many service types to balance, with the balance relationships being strong. In terms of spatial distribution characteristics, the spatial distribution range of land use conflicts in the study area was mainly characterized by weak and moderate conflict areas; however, land use conflicts were more severe in some local areas. The spatial distribution structure of land use conflicts in the study area showed a medium-weak-medium pattern from the periphery to the central part. Strong and extremely strong conflict areas were concentrated in natural or semi-natural areas.

BackgroundUnder the condition of sub-cooled nucleate boiling (SNB), corrosion products in primary coolant of nuclear reactor will deposit on the outer surface of fuel cladding, which is commonly called fuel crud. Previous literature shown, zinc injection in primary coolant is an important method to inhibit the fuel crud deposition on the fuel cladding surface.PurposeThis study aims to investigate the influence of zinc concentration on the behavior of fuel crud deposition, and eventually provide guidance for zinc injection in primary coolant of nuclear power plant.MethodsThe fuel crud deposition tests of domestic zirconium alloy fuel cladding in different zinc concentrations were carried out by using a self-made fuel crud deposition device. Tubular crud deposition test specimen with built-in heating unit was designed and prepared for simulation study. After the tests, stereo microscope (SM) and scanning electron microscope (SEM) were employed to observe the macro and micro morphology of fuel crud whilst the composition of of fuel crud was observed and analyzed by the energy dispersive spectroscopy (EDS) with SEM, and X-ray photoelectron spectroscopy (XPS) was used to analyze the contents of Zn and B elements in the crud phase and inside the crud.ResultsObservation results show that the chimney-like crud formed on the fuel cladding surface becomes less obvious with increasing the zinc concentration in the coolant and the crud surface becomes flatter. Simutabeously, the crud thickness, the ratio of Ni/Fe and the boron precipitation mass within the crud are decreasing with increase of the zinc concentration. When the zinc concentration increases to 100 μg‧L-1, new Zn-containing phases precipitate within the crud.ConclusionsWithin the zinc concentration of 0~100 μg‧L-1, zinc injection in primary coolant of reactor can significantly inhibit the crud deposition on the fuel cladding surface.

Seismic monitoring data for the past 50 years in the Three Gorges Reservoir area show that the reservoir head area is a typical weak seismic region with low seismicity before impoundment and that the epicenters were concentrated in the east and west sides of the Zigui Basin, most of which were natural tectonic earthquakes. After impoundment, the seismic activity shifted to the segment between Badong and Zigui along the Yangtze River, mainly within 5 km of the reservoir bank. The seismogenesis was categorized into four types; Karst collapse earthquakes, earthquakes caused by Karst gas explosion, mining tunnel collapse earthquakes, and rock (terrane) slip earthquakes, all of which are related to the lithology, structure, and tectonics of near-surface geological bodies of the area. Compared with the seismicity before impoundment, the seismic frequency increase was remarkable, with most of the magnitudes below Ms2. 0. Therefore, the intensity of the earthquakes remained at a low level. On November 22, 2008, a magnitude 4. 1 earthquake, the largest earthquake recorded since impoundment, occurred in Quyuan Town, Zigui County. The intensity and PGA of reservoir-induced earthquakes are higher than those of tectonic earthquakes with equal magnitude, but the peak intensity of reservoir-induced earthquakes is not likely to go beyond that of the estimated range from earlier studies.

The spatial and temporal slip distribution of the Lushan earthquake was estimated using teleseismic body wave data. To perform a stable inversion, we applied smoothing constraints and determined their optimal relative weights on the observed data using an optimized Akaike’s Bayesian Information Criterion (ABIC). The inversion generated the source parameters. Strike, dip and slip were 218°, 39° and 100. 8°, respectively. A seismic moment (M0) was 2. 1 × 1020 Nm with a moment magnitude (Mw) of 6. 8, and a source duration was approximately 30 second. The rupture propagated along the dip direction, and the maximum slip occurred at the hypocenter. The maximum slip was approximately 2. 1 m, although this earthquake did not cause an apparent surface rupture. The energy was mainly released within 10 second. In addition, the Lushan earthquake was apparently related to the 2008 Wenchuan earthquake. However, the question of whether it was an aftershock of the Wenchuan earthquake requires further study.

The seismic intensities, lithologic characteristics and terrain features from a 3000 km2-region near the epicenter of the Lushan earthquake are used to analyze earthquake-induced geological disaster. The preliminary results indicate that secondary effects of the earthquake will affect specific areas, including those with glutenite and carbonate bedrock, a seismic intensity of IX, slopes between 40° and 50°, elevations of less than 2500 m, slope change rates between 20° and 30°, slope curvatures from –1 to –0. 5 and 0. 5 to 1, and relief between 50 and 100 m. Regions with susceptibility indices greater than 0. 71 are prone to landslides and collapses. The secondary features are mainly distributed on both sides of the ridges that extend from Baosheng to Shuangshi and from Baosheng to Longxing. Other features are scattered on both sides of the ridges that extend from Qishuping to Baosheng and from Masangping to Lingguan. The distribution of the earthquake-related features trends in the NE direction, and the area that was most affected by the Lushan earthquake covers approximately 52.4 km2.

A M6.6 earthquake occurred on July 22, 2013 at Dingxi Basin in Gansu Province within the tectonially expanding northeastern margin of the Qinghai-Tibet Plateau. We analyzed the geomorphological features of the Dingxi Basin by using remote sensing technology and compared them with local seismic activity. We found that most of the river basins are at the robust stage of development and that the major local rivers and the development of some basins boundaries are controlled by the seismic faults. Among four zones identified to have significant tectonic activities, the northwestly-oriented one located in the south has the highest seismic activity, and it is where the M6. 6 earthquake occurrred.

The Ms8.0 Wenchuan earthquake in 2008 caused huge casualties, economic losses, and building damages, which are analyzed. The results show that damages of houses designed according to the current seismic code were significantly smaller than those without such design, suggesting that the code has achieved the desired goal of seismic fortification. Buildings of different kinds of structures showed large differences in damages : Houses with steel-frames and shear walls or steel structures suffered the least damages: those with frames or with brick-and-concrete structures suffered more; old cottages, the most.

Federated learning is a distributed learning framework designed to protect user privacy, widely applied across various domains. However, existing federated learning algorithms face challenges, including slow convergence, significant loss fluctuations during aggregation, and imbalanced client sampling. To address these issues, this paper introduces a high-performance federated learning aggregation algorithm. This algorithm combines a cyclic adaptive learning rate adjustment strategy with client-weighted random sampling, addressing the aforementioned problems. Weighted random sampling assigns client weights based on their sampling frequency, balancing client sampling rates and contributions to enhance model aggregation. Additionally, it adapts the learning rate based on client loss variations and communication rounds, accelerating model convergence and reducing communication costs. To evaluate this high-performance algorithm, experiments are conducted using well-known datasets MNIST and CIFAR-10. The results demonstrate significant improvements in convergence speed and loss stability. Compared to traditional federated learning algorithms, our approach achieves faster and more stable convergence while effectively reducing training costs. [ABSTRACT FROM AUTHOR]