Aiming at the issues of more difficult to solve and lower precision of six-axis robotic arm in inverse kinematics (IK) solution, a multi-strategy improved dung beetle optimization algorithm (ECDBO) is proposed. It improves performance in four aspects: population initiation, global search capability, search direction perturbation and jumping out of local optima. Sobol sequence strategy was introduced to initialize the dung beetle population, resulting in a more even distribution of individual dung beetles and increasing the diversity of initial population. Boundary optimization strategy is adopted to balance the requirements on search capability at different times. This approach enhances global search capability at the beginning and local search capability at the end of an iteration. Propose hybrid directional perturbation strategy to change the search direction of rolling dung beetles and stealing dung beetles. It allows for more detailed exploration and improves convergence accuracy. The Levy flight strategy is incorporated to perturb current optimal solution, enhancing algorithm’s ability to jump out of the local optimum. In order to verify performance of ECDBO algorithm, CEC2017 function tests and robotic arm IK solving experiments were conducted and compared with other algorithms. ECDBO ranked first on 21 functions in the 30 dimensions tested in CEC2017 and on 27 functions in the 100 dimensions. ECDBO performs well in the IK solving experiments of two robotic arms with better accuracy than other algorithms. The experimental results show that the ECDBO algorithm significantly improves the convergence and accuracy, and also performs excellently on the IK solving problem.

Cyber breaches pose a significant threat to both enterprises and society. Analyzing cyber breach data is essential for improving cyber risk management and developing effective cyber insurance policies. However, modeling cyber risk is challenging due to its inherent characteristics, including sparsity, heterogeneity, heavy tails, and dependence. This work introduces a cluster-based dependence model that captures both temporal and cross-group dependencies, providing a more accurate representation of multivariate cyber breach risks. The proposed framework employs a cluster-based kernel approach to model breach severity, effectively handling heterogeneity and extreme values, while a copula-based method is used to capture multivariate dependence. Our findings, validated through both empirical and synthetic studies, demonstrate that the proposed model effectively captures the statistical characteristics of multivariate cyber breach risks and outperforms commonly used models in predictive accuracy. Furthermore, we show that our approach can enhance cyber insurance pricing by generating more profitable insurance contracts.

Cosmogenic 7Be and 10Be are effective tracers for studying atmospheric dynamics and Earth’s surface processes, with over 90% of these isotopes reaching the surface via wet deposition. However, the characteristics and influencing factors of 7Be and 10Be wet deposition remain unclear in different regions, limiting the precision of these nuclides as tracers of environmental change. This study analyzes the annual variation of 7Be and 10Be wet deposition in Xi’an and examines the impact of precipitation on their deposition. Ultra-trace levels of 7Be and 10Be in precipitation were synchronously measured using state-of-the-art accelerator mass spectrometry. One-year (July 30, 2020 to September 3, 2021), high-frequency (individual rain events) and time-synchronized series of observations of 7Be and 10Be wet deposition data (n = 49) were analyzed. The total annual wet deposition fluxes of 7Be and 10Be in central China (34.22°N, 109.01°E) for 2020/21 were (218 ± 24) × 108 atoms·m–2·yr–1 and (314 ± 16) × 108 atoms·m–2·yr–1, respectively. Precipitation amount, intensity, and duration were quantitatively analyzed for their effects on total wet deposition flux, mean concentration, washout ratio, deposition velocity, and scavenging coefficient of 7Be and 10Be during individual rain events. The results indicate that precipitation amount is the most significant factor influencing the wet deposition flux of both nuclides.

The cycling of carbon in riverine systems is a critical component of global carbon cycle research. However, the sources and performances of riverine carbon in the Qinling Mountains, a pivotal hydrological nexus in China, remain poorly understood. This study investigates the seasonal variations of dissolved organic carbon (DOC) concentration in the Tianyu River within the Qinling Mountains. By utilizing a combination of carbon isotopic signatures (Δ14C-δ13C) and the stepped-combustion method, we examined the sources of DOC and the contribution ratio of each end-member. Our findings reveal that: (1) the concentrations and dual carbon isotope ratios of DOC in the Tianyu River are influenced by regional climatic factors, exhibiting distinct seasonal patterns; (2) the 14C age of DOC in the Tianyu River is comparatively older than the global average for rivers but younger than that of China’s three major rivers (the Yellow, Yangtze, and Pearl Rivers); and (3) the DOC mainly comes from exogenous sources, with a proportion of about 85.8%–88.4%. Vegetation and riverine sediments are identified as primary contributors. These findings suggest that exemplary ecological preservation exists within the Qinling region while operating within an efficient carbon cycling system. This investigation provides initial insights into how regional climatic conditions influence riverine carbon cycles and enhances our understanding of biogeochemical processes related to carbon.

Ultra-thin liquid sheets generated by impinging two liquid jets are crucial high-repetition-rate targets for laser ion acceleration and ultra-fast physics, and serve widely as barrier-free samples for structural biochemistry. The impact of liquid viscosity on sheet thickness should be comprehended fully to exploit its potential. Here, we demonstrate experimentally that viscosity significantly influences thickness distribution, while surface tension primarily governs shape. We propose a thickness model based on momentum exchange and mass transport within the radial flow, which agrees well with the experiments. These results provide deeper insights into the behaviour of liquid sheets and enable accurate thickness control for various applications, including atomization nozzles and laser-driven particle sources.

This study explores an interesting fluid–structure interaction scenario: the flow past a flexible filament fixed at two ends. The dynamic performance of the filament under various inclination angles ($\theta$) was numerically investigated using the immersed boundary method. The motion of the filament in the $\theta$–$Lr$ space was categorised into three flapping modes and two stationary modes, where $Lr$ is the ratio of filament length to the distance between its two ends. The flow fields for each mode and their transitions were introduced. A more in-depth analysis was carried out for flapping at a large angle (FLA mode), which is widely present in the $\theta$–$Lr$ space. The maximum width $W$ of the time-averaged shape of the filament has been shown to strongly correlate with the flapping frequency. After non-dimensionalising based on $W$, the flapping frequency shows little variation across different $Lr$ and $\theta$. Moreover, two types of lift variation process were also identified. Finally, the total lift, drag and lift-to-drag ratio of the system were studied. Short filaments, such as those with $Lr\leqslant 1.5$, were shown to significantly increase lift and the lift-to-drag ratio over a wide range of $\theta$ compared with a rigid plate. Flow field analysis concluded that the increases in pressure difference on both sides of the filament, along with the upper part of the flexible filament having a normal direction closer to the $y$ direction, were the primary reasons for the increase in lift and lift-to-drag ratio. This study can provide some guidance for the potential applications of flexible structures.

We establish sharp upper bounds for shifted moments of quadratic Dirichlet L-function under the generalized Riemann hypothesis. Our result is then used to prove bounds for moments of quadratic Dirichlet character sums.

This paper provides an overview of the current status of ultrafast and ultra-intense lasers with peak powers exceeding 100 TW and examines the research activities in high-energy-density physics within China. Currently, 10 high-intensity lasers with powers over 100 TW are operational, and about 10 additional lasers are being constructed at various institutes and universities. These facilities operate either independently or are combined with one another, thereby offering substantial support for both Chinese and international research and development efforts in high-energy-density physics.

Substantial changes resulting from the interaction of environmental and dietary factors contribute to an increased risk of obesity, while their specific associations with obesity remain unclear. We identified inflammation-related dietary patterns (DP) and explored their associations with obesity among urbanised Tibetan adults under significant environmental and dietary changes. Totally, 1826 subjects from the suburbs of Golmud City were enrolled in an open cohort study, of which 514 were followed up. Height, weight and waist circumference were used to define overweight and obesity. DP were derived using reduced rank regression with forty-one food groups as predictors and high-sensitivity C-reactive protein and prognostic nutritional index as inflammatory response variables. Altitude was classified as high or ultra-high. Two DP were extracted. DP-1 was characterised by having high consumptions of sugar-sweetened beverages, savoury snacks, and poultry and a low intake of tsamba. DP-2 had high intakes of poultry, pork, animal offal, and fruits and a low intake of butter tea. Participants in the highest tertiles (T3) of DP had increased risks of overweight and obesity (DP-1: OR = 1·37, 95 % CI 1·07, 1·77; DP-2: OR = 1·48, 95 % CI 1·18, 1·85) than those in the lowest tertiles (T1). Participants in T3 of DP-2 had an increased risk of central obesity (OR = 2·25, 95 % CI 1·49, 3·39) than those in T1. The positive association of DP-1 with overweight and obesity was only significant at high altitudes, while no similar effect was observed for DP-2. Inflammation-related DP were associated with increased risks of overweight and/or obesity.

Prehistoric humans seem to have preferred inhabiting small river basins, which were closer in distance to most settlements compared to larger rivers. The Holocene landscape evolution is considered to have played a pivotal role in shaping the spatiotemporal patterns of these settlements. In this study, we conducted comprehensive research on the relationship between landscape evolution and settlement distribution within the Huangshui River basin, which is a representative small river in Central China with numerous early settlements, including a prehistoric city known as the Wangjinglou site (WJL). Using geoarchaeological investigations, optically stimulated luminescence dating, pollen analysis, and grain-size analysis, we analyzed the characteristics of the Holocene environment. The results indicate the presence of two distinct geomorphic systems, namely the red clay hills and the river valley. The red clay hills, formed in the Neogene, represent remnants of the Songshan piedmont alluvial fan that was eroded by rivers. There are three grades of terraces within the river valley. T3 is a strath terrace and formed around 8.0 ka. Both T2 and T1 are fill terraces, which were developed around 4.0 ka and during the historical period, respectively. The sedimentary features and pollen analysis indicate the existence of an ancient lake-swamp on the platform during 11.0–9.0 ka. This waterbody gradually shrank during 9.0–8.0 ka, and ultimately disappeared after 8.0 ka. Since then, the development of large-scale areas of water ceased on the higher geomorphic units. River floods also cannot reach the top of these high geomorphic units, where numerous prehistoric settlements are located, including the Xia–Shang cities of the WJL site. Our research demonstrates that landscape stability supported the long-term and sustainable development of ancient cultures and facilitated the establishment of the WJL ancient cities in the region.

Trioctahedral phyllosilicate minerals are widely distributed on the Earth’s surface, especially in soil. The mineral–water interfacial reaction of lizardite, chlorite and talc, with various structural properties (tetrahedral sheet, octahedral sheet, 1:1-type and 2:1-type interlayer domain/two-dimensional structural units), was carried out in sulfuric acid solution (1 mol L–1). The mineral samples were characterized by powder X-ray diffraction, Fourier-transform infrared spectroscopy, scanning and transmission electron microscopy and inductively coupled plasma mass spectrometry. The dissolution concentration, dissolution rate, dissolution rules and structural changes of the components during the dissolution processes of the various two-dimensional structural units were studied. The results show that the dissolution concentrations of Si and Mg in the sulfuric acid solution decrease in the following order: chlorite > lizardite > talc and lizardite > chlorite > talc. The dissolution rates of Si in chlorite and Mg in lizardite are the greatest, while talc is the most stable compared with lizardite and chlorite. With increasing interfacial reaction time and the dissolution of the ionic components of the minerals, the structure of lizardite is gradually destroyed; the structural destruction of chlorite is more obvious during the early stages of the reaction; and the structure of talc does not significantly change over the course of the entire reaction. By analysing the microtopography of the minerals, it was found that the structural failure of lizardite occurred from the surface to the interior. Chlorite had more structural defects and showed collapse of the layered structure during structural failure. The surface layer of talc decomposed by corrosion into a small lamellae structure attached to the surface, but there was no obvious structural change similar to those of lizardite and chlorite. The relationship between the evolution of composition and structure during the mineral–water interfacial reaction process with the two-dimensional structure layer type provides the mineralogical basis for studying the coupling mechanism of the migration and transformation of materials in key regions of the Earth.

Different two-dimensional structural units of layered silicate minerals have different chemical and reaction properties. Sulfuric acid solution mineral-leaching systems with pH of 2.0, 4.0 and 6.0 were constructed to investigate the differential dissolution properties of lizardite (1:1 type), chlorite and talc (2:1 type minerals) and the chemical kinetic mechanism of the mineral–water interface reaction. The results showed that the dissolution efficiency of Mg in lizardite is higher than that of chlorite and talc in acidic environments (pH of 2.0, 4.0 and 6.0). The dissolution efficiency of Mg in chlorite is greater than that of talc for acidic environments when pH is 2.0 and 4.0, but chlorite and talc have nearly identical Mg dissolution efficiencies at a pH of 6.0. This phenomenon is related to the defect site on the tetrahedral sheet of chlorite and is controlled by the change of the dissolution efficiency of Al. The dissolution rates of Mg and Si in lizardite, chlorite and talc decreased with the increase of reaction time in the acidic medium for pH = 2.0, 4.0 and 6.0, and there are two linear dissolution trends at different pH values. The dissolution efficiencies of Mg and Si in lizardite, chlorite and talc were simulated and predicted by establishing a logistic model. It was found that the maximum dissolution efficiency of 2:1 type minerals chlorite and talc are only 4.72% and 1.58%, which is much lower than that of 1:1 type lizardite. This research on the reaction mechanism and dissolution kinetics of lizardite, chlorite and talc not only helps to deepen the understanding of the mineral–water interface interaction, but also reveals the different rules for Mg, Si and Al dissolution in different types of trioctahedral mineral–water interface reactions, and provides a crystal chemical basis for the ion migration and action mechanism of minerals.

Serpentine is widely distributed in the regolith and occurs in different types (chrysotile, lizardite, antigorite). The physical and chemical processes such as composition dissolution and structure evolution of serpentine occur constantly under the action of aqueous solutions. Based on the similarities and differences of polysomic structures and properties of chrysotile (tubular shapes) and lizardite (flat structural layers), the mineral–water interfacial reaction of these two minerals was carried out in a sulfuric acid solution with a concentration of 1 mol L–1. The mineral samples were characterized by powder X-ray diffraction, Fourier-transform infrared spectroscopy, scanning and transmission electron microscopy, Brunauer–Emmett–Teller surface area analysis, magic angle spinning nuclear magnetic resonance, and inductively coupled plasma mass spectrometry. The Si, Mg, and Fe dissolution concentrations, dissolution rates, and dissolution rules and structural changes of chrysotile and lizardite were studied and compared. The results show that H+ is more aggressive toward lizardite in sulfuric acid solution. The dissolution rate of Si, Mg, and Fe was faster, the dissolution concentration was greater, and structural changes occurred preferentially in lizardite. Specifically, Mg dissolved first in the octahedral sheets, and Si and Fe dissolved later in the tetrahedral sheets. After the water interfacial reaction with the sulfuric acid solution, the ion dissolution rates of both chrysotile and lizardite were Mg > Fe > Si. In summary, this work investigates the mineral–water interfacial reaction of chrysotile and lizardite in sulfuric acid media from different crystal structures and demonstrates that the crystal structure has a significant effect on the acid reactivity of lizardite minerals. Furthermore, the crystal chemistry patterns for the structural dissociation of different two-dimensional structural units were studied. This work provides a mineralogical basis for the study of the mechanisms of ion migration and crystal-structure evolution of serpentine under acidic media.