Search Results (53)

It is vital to stabilize pillar dams in underground reservoirs in coal mine goafs to protect groundwater resources and quarry safety, practice green mining, and protect the ecological environment. Considering the actual occurrence of coal pillar dams in underground reservoirs, acoustic emission (AE) mechanical tests were performed on dry, naturally absorbed, and soaked coal samples. According to the mechanical analysis, Quantitative analysis revealed that dry samples exhibited the highest mechanical parameters (peak strength: 12.3 ± 0.8 MPa; elastic modulus: 1.45 ± 0.12 GPa), followed by natural absorption (peak strength: 9.7 ± 0.6 MPa; elastic modulus: 1.02 ± 0.09 GPa), and soaked absorption showed the lowest values (peak strength: 7.2 ± 0.5 MPa; elastic modulus: 0.78 ± 0.07 GPa). The rate of mechanical deterioration increased by ~25% per 1% increase in moisture content. It was identified that the internal crack development presented a macrofracture surface initiating at the sample center and expanding radially outward, and gradually expanding to the edges by adopting AE seismic source localization and the K-means clustering algorithm. Soaked absorption was easier to produce shear cracks than natural absorption, and a higher water content increased the likelihood. The b-value of the AE damage evaluation index based on crack development was negatively correlated with the rock damage state, and the S-value was positively correlated, and both effectively characterized it. The research results can offer reference and guidance for the support design, monitoring, and warning of coal pillar dams in underground reservoirs. (The samples were tested under two moisture conditions: (1) ‘Soaked absorption’—samples fully saturated by immersion in water for 24 h, and (2) ‘Natural absorption’—samples equilibrated at 50% relative humidity and 25 °C for 7 days). Full article

Autonomous exploration is a fundamental challenge for various applications of unmanned aerial vehicles (UAVs). To enhance exploration efficiency in large-scale unknown environments, we propose a Fast Autonomous Exploration Framework (FAEM) designed to enable efficient autonomous exploration and real-time mapping by UAV quadrotors in unknown environments. By employing a hierarchical exploration strategy that integrates geometry-constrained, occlusion-free ellipsoidal viewpoint generation with a global-guided kinodynamic topological path searching method, the framework identifies a global path that accesses high-gain viewpoints and generates a corresponding highly maneuverable, energy-efficient flight trajectory. This integrated approach within the hierarchical framework achieves an effective balance between exploration efficiency and computational cost. Furthermore, to ensure trajectory continuity and stability during real-world execution, we propose an adaptive dynamic replanning strategy incorporating dynamic starting point selection and real-time replanning. Experimental results demonstrate FAEM’s superior performance compared to typical and state-of-the-art methods in existence. The proposed method was successfully validated on an autonomous quadrotor platform equipped with LiDAR navigation. The UAV achieves coverage of 8957–13,042 m³ and increases exploration speed by 23.4% compared to the state-of-the-art FUEL method, demonstrating its effectiveness in large-scale, complex real-world environments. Full article

In this article, a robust adaptive dynamic position-control problem is addressed for full-actuated surface vessels under coupled uncertainties from unmodeled hydrodynamic effects and time-varying external disturbances. To obtain a high-performance dynamic position controller, a reinforcement learning (RL) weights law involving actor and critic networks is designed without knowledge of the model dynamics and the disturbance parameters. This can enhance the robustness of the closed-loop control system. Furthermore, dynamic surface control is integrated to diminish the design complexity resulting from the derivative of the kinematics, while ensuring semi-global uniformly ultimately bounded (SGUUB) stability through Lyapunov-based synthesis. Simulations are carried out to evaluate the superiority and feasibility of the proposed algorithm. Full article

New genes play a critical role in phenotypic diversity and evolutionary innovation. Parasitoid wasps, a highly abundant and diverse group of insects, parasitize other arthropods and exhibit remarkable evolutionary adaptations, such as evading host immune responses and exploiting host resources. However, the specific contributions of new genes to their unique traits remain poorly understood. Here, we identified 480 new genes that emerged after the Nasonia-Pteromalus divergence. Among these, 272 (56.7%) originated through DNA-mediated duplication, representing the largest proportion, followed by 77 (16.0%) derived from RNA-mediated duplication and 131 (27.3%) that arose de novo. Comparative analysis revealed that these new genes generally have shorter coding sequences and fewer exons compared to single-copy older genes conserved in the seven parasitoid wasps. These new genes are predominantly expressed in the reproductive glands and exhibit venom gland-biased expression. Notably, gene co-expression network analysis further identified that a new gene may act as a hub by interacting with older genes to regulate venom-related networks rather than directly encoding venom proteins. Together, our findings provide novel insights into the role of new genes in driving venom innovation in parasitoid wasps. Full article

The ultra-thin Invar alloy strips are widely used in the manufacture of the fine masks; cold rolling of such thin strips (<100 μm) poses significant difficulties, primarily due to the limited number of grains within the thickness range. Consequently, it is important to understand the grain structure and property evolutions of the ultra-thin Invar alloy strips during cold rolling. In this study, an annealed Invar36 alloy strip, 100 µm thick, was cold rolled to different thicknesses, and the surface deformation morphologies, cross-sectional grain structure, intracrystalline microstructure and tensile properties of these thin strips were characterized and analyzed. The results show that plastic deformation of the initial annealed equiaxed grains is not uniform, depending on the grain orientation, resulting in different slip bands morphologies, unevenness and increase in roughness. Meanwhile, the grain rotation and rolling texture develop with increasing cold rolling reduction. The dislocation density in the 60% cold-rolled strip is about decuple that of the original annealed strip, and high-density tangled dislocations are formed, making the tensile strength increase from 430 MPa to 738 MPa. Grain refining and proper intermediate annealing are proposed to optimize the thickness uniformity, evenness and surface roughness. Full article

Mobile welding robots have attracted considerable attention due to their flexible movement and robust adaptability, offering substantial market potential. However, the complexity of their operational conditions poses specific demands on robot configurations, with no established design methodology available at the time. To address this challenge, we constructed Lagrange’s equations for wheeled mobile welding robots. Through simplification and deduction analysis, we concluded that larger wheeled mobile welding robots are suited for paths with larger curvature radii, whereas smaller ones are more appropriate for paths with smaller curvature radii. Based on the above analysis and considering the load-bearing capacity of the robot, we proposed a configuration design method for wheeled mobile welding robots, evolving from large to small and micro wheels, including track constraints and wheel number adjustments. Subsequently, prototype robots, including magnetic wheel, tracked, and flexible contour tracing mobile welding robots, have been developed to accommodate various operational conditions. Welding experiments demonstrate that these three configurations, distinguished by their travel path curvature radii, can effectively meet the mobile welding requirements of their respective environments. The effectiveness of the configuration design of wheeled mobile welding robots under different working conditions has been verified. Full article

Siberian wildrye (Elymus sibiricus L.), a model Elymus Gramineae plant, has high eco-economic value but limited seed and forage yield. TCP transcription factors are widely regarded as influencing yield and quality and being crucial for growth and development; still, this gene family in Siberian wildrye remains unexplored. Therefore, this study looked at the Siberian wildrye TCP gene family’s reaction to several abiotic stresses, its expression pattern, and its potential evolutionary path. Fifty-four members of the EsTCP gene family were discovered. There are two major subfamilies based on the phylogenetic tree: 27 of Class I (PCF) and 27 of Class II (12 CIN-type and 15 TB1/CYC-type). Gene structure, conserved motif, and sequence alignment analyses further validated this classification. Cis-elements found in the promoter region of EsTCPs are associated with lots of plant hormones and stress-related reactions, covering drought induction and cold tolerance. EsCYC5, EsCYC6, and EsCYC7 may regulate tillering and lateral branch development. EsPCF10’s relative expression was significant under five stresses. Additionally, eight EsTCP genes are potential miR319 targets. These findings highlight the critical significance of the TCP gene family in Siberian wildrye, laying the groundwork for understanding the function of the EsTCP protein in abiotic stress studies and high-yield breeding. Full article

High-entropy alloys have garnered significant attention due to their unique composition and exceptional properties. Additive manufacturing technology, with its distinctive processing methods, offers new options for the fabrication of high-entropy alloys. However, due to the diversity of high-entropy alloys and additive manufacturing technologies, it is imperative to provide a comprehensive overview of the high-entropy alloys produced using various additive manufacturing methods. This paper presents a summary of the microstructure, mechanical properties, and corrosion resistance of high-entropy alloys fabricated using different additive manufacturing techniques. This paper initially reviews the impact of various additive manufacturing process parameters and the influence of different elements on the microstructure of additively manufactured high-entropy alloys. Subsequently, it discusses the effects of different additive manufacturing techniques on mechanical properties and summarizes four strengthening mechanisms in additively manufactured high-entropy alloys. Additionally, the corrosion resistance of various additively manufactured high-entropy alloys is summarized. Finally, based on the review of additively manufactured high entropy alloys presented in this paper, the current challenges and future research directions are proposed. Full article

Graph Contrastive Learning (GCL) seeks to learn nodal or graph representations that contain maximal consistent information from graph-structured data. While node-level contrasting modes are dominating, some efforts have commenced to explore consistency across different scales. Yet, they tend to lose consistent information and be contaminated by disturbing features. We propose MUX-GCL, a novel cross-scale contrastive learning framework that addresses these key challenges in GCL by leveraging multiplex representations as effective patches to enhance information consistency. Our method introduces a soft-negative contrasting strategy based on positional affinities to reduce false negatives, thereby minimizing information loss during multi-scale contrasts. While this learning mode minimizes contaminating noises, a commensurate contrasting strategy using positional affinities further avoids information loss by correcting false negative pairs across scales. Extensive downstream experiments demonstrate that MUX-GCL yields multiple state-of-the-art results on public datasets. Our theoretical analysis further guarantees the new objective function as a stricter lower bound of mutual information of raw input features and output embeddings, which rationalizes this paradigm. Full article

Blockchain technology can be used in the IoT to ensure the data privacy collected by sensors. In blockchain systems, consensus mechanisms are a key technology for maintaining data consistency and correctness. Among the various consensus protocols, asynchronous Byzantine consensus protocols offer strong robustness as they do not rely on any network timing assumptions during design. As a result, these protocols have become a research hotspot in the field of blockchain. Based on different structural design approaches, asynchronous Byzantine consensus protocols can be divided into two categories: protocols based on the DAG structure and protocols based on the ACS structure. The paper describes their principles and summarizes the related research works. The advantages and disadvantages of the protocols are also compared and analyzed. At the end of the paper, future research directions are identified. Full article

Temporal and spatial changes in non-point source pollution, driven by significant alterations in land use due to increased human activity, have considerably affected the quality of groundwater, surface water, and soil environments in the region. This study examines the Weihe River basin in greater detail, an area heavily impacted by human activity. The study developed the River Section Potential Pollution Index (R-PPI) model using the Potential Non-Point Source Pollution Index (PNPI) model in order to investigate the dynamic changes in River Section Potential Pollution (R-PP) over a 31-year period and its associated risks, especially those related to land use and land cover change (LUCC). The predominant land uses in the Weihe River Basin are cropland, grassland, and forest, making up around 97% of the basin’s total area. The Weihe River Basin underwent a number of soil and water conservation initiatives between 1990 and 2020, which significantly decreased the potential pollution risk in the river segment. The research separated the R-PP risk values in the area into five different categories using a quantile classification technique. According to the data, there is a polarization of R-PP risk in the area, with downstream parts especially having an increased risk of pollution in river segments impacted by human activity. On the other hand, river segments in the middle and upper reaches of the basin showed a discernible decline in possible pollution risk throughout the study period. The Weihe River Basin’s rapid urbanization and land degradation are to blame for the current increase in R-PP risk. The substantial influence of LUCC on the dynamic variations in R-PP risk in the Weihe River Basin is highlighted by this study. Additionally, it offers crucial information for upcoming conservation initiatives and urban planning guidelines meant to enhance the area’s ecological well-being and environmental standards. Full article

Microbial fuel cell (MFC) technology holds significant promise for the production of clean energy and treatment of pollutants. Nevertheless, challenges such as low power generation efficiency and the high cost of electrode materials have impeded its widespread adoption. The porous microstructure of biochar and the exceptional photocatalytic properties of rutile endow it with promising catalytic potential. In this investigation, we synthesized a novel Rutile–Biochar (Rut-Bio) composite material using biochar as a carrier and natural rutile, and explored its effectiveness as a cathode catalyst to enhance the power generation efficiency of MFCs, as well as its application in remediating heavy metal pollution. Furthermore, the impact of visible light conditions on its performance enhancement was explored. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analysis validated the successful fabrication of rutile composites loaded with biochar. The maximum current density and power density achieved by the MFCs were 153.9 mA/m² and 10.44 mW/m², respectively, representing a substantial increase of 113.5% and 225% compared to the control group. In addition, biochar-supported rutile MFCs showed excellent degradation performance of heavy metal pollutants under light conditions. Within 7 h, the Cr⁶⁺ degradation rate reached 95%. In contrast to the blank control group, the removal efficiency of pollutants exhibited increases of 630.8%. The cyclic degradation experiments also showcased the remarkable stability of the system over multiple cycles. This study successfully integrated natural rutile and biochar to fabricate highly efficient cathode photocatalyst composites, which not only enhanced the power generation performance of MFCs but also presented an environmentally sustainable and economically viable method for addressing heavy metal pollution. Full article

Hysteresis is a fundamental characteristic of magnetic materials. The Jiles–Atherton (J-A) hysteresis model, which is known for its few parameters and clear physical interpretations, has been widely employed in simulating hysteresis characteristics. To better analyze and compute hysteresis behavior, this study established a state space representation based on the primitive J-A model. First, based on the five fundamental equations of the J-A model, a state space representation was established through variable substitution and simplification. Furthermore, to address the singularity problem at zero crossings, local linearization was obtained through an approximation method based on the actual physical properties. Based on these, the state space model was implemented using the S-function. To validate the effectiveness of the state space model, the hysteresis loops were obtained through COMSOL finite element software and tested on a permalloy toroidal sample. The particle swarm optimization (PSO) method was used for parameter identification of the state space model, and the identification results show excellent agreement with the simulation and test results. Finally, a closed-loop control system was constructed based on the state space model, and trajectory tracking experiments were conducted. The results verify the feasibility of the state space representation of the J-A model, which holds significant practical implications in the development of magnetically shielded rooms, the suppression of magnetic interference in cold atom clocks, and various other applications. Full article

Within the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) complex, two cryptic species, namely Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED), are important invasive pests affecting global agriculture and horticulture. They were introduced into China sequentially in the mid-1990s and around 2003, respectively. Subsequently, the latter invader MED has outcompeted the earlier invader MEAM1, becoming the dominant population in the field. Although extensive studies have explored the underlying mechanisms driving this shift, the contribution of population genetics remains notably underexplored. In this study, we analyzed the genetic diversity and structure of 22 MED and 8 MEAM1 populations from various regions of China using mitochondrial DNA sequencing and microsatellite genotyping. Our results indicate low and moderate levels of genetic differentiation among geographically separate populations of MED and MEAM1, respectively. Median-joining network analysis of mtCOI gene haplotypes revealed no clear geographic structuring for either, with common haplotypes observed across provinces, although MED had more haplotypes. Comparative analyses revealed that MED presented greater genetic diversity than MEAM1 on the basis of two markers. Furthermore, analysis of molecular variance supported these findings, suggesting that while some genetic variation exists between populations, a significant amount is also present within populations. These findings reveal the population genetics of the two invasive cryptic species of the B. tabaci complex in China and suggest that the disparities in genetic diversity drive the displacement of their populations in the field. This work also provides valuable information on the genetic factors influencing the population dynamics and dominance of these invasive whitefly species. Full article