Search Results (2,921)

Stochastic Process Mining, in particular, Markov processes, is used to represent uncertainty and variability in Activities of Daily Living (ADLs). However, the Markov models inherently assume that the time spent in each state must follow an exponential distribution. This presents a significant challenge to model real-life complexities in ADLs. Therefore, this paper employs semi-Markov models on publicly available ADL event logs to model state durations, where results are validated via goodness-of-fit tests (Kullback–Leibler, Kolmogorov–Smirnov, Cramér–von Mises). Synthetic durations are generated using the inverse transform sampling technique. To simulate dementia-based behaviours, the weights of the mixture model are altered to reflect prolonged duration in napping, toileting, meal, and drink preparation. These anomalies are then detected through the employment of log-likelihood ratio and chi-square tests. Experimental results demonstrate that the proposed approach can be used to reliably identify abnormal ADL durations, offering a proven framework to track early detection of behavioural shifts, and showcasing the effectiveness of detecting duration-based anomalies in ADL. By identifying such anomalies, our work aims to detect deterioration in the smart home resident’s condition, focusing in particular on their ability to execute different ADLs. Full article

Excavators are critical equipment in mining, construction, and other fields. The four-point contact slewing bearings used in their slewing mechanisms operate under harsh conditions such as heavy loads and impacts. Furthermore, the bearing rings are prone to elliptical deformation after installation, making them susceptible to premature failure. To address this issue, this paper establishes a mechanical bearing model to investigate the load distribution among balls and the fatigue life of the bearing under elliptical deformation of the rings. It systematically analyzes the influence of key design parameters. The research finds that elliptical deformation of the rings leads to contact angle deviation and a reduction in load-bearing balls, resulting in severe degradation of bearing fatigue life; therefore, its occurrence must be strictly controlled. Designing with a groove curvature radius coefficient within the range of 0.51 to 0.52 achieves an optimal balance between fatigue life and the four-point contact geometry of the balls. There exists an “optimal clearance” that maximizes bearing fatigue life; when considering significant elliptical deformation, the clearance design should be appropriately increased. Increasing the design contact angle enhances load capacity and helps mitigate the effects of elliptical deformation. However, an excessively large contact angle can cause ellipse truncation in the raceway contact zone; thus, the contact angle should be designed based on practical conditions. Increasing the number of balls can improve the influence of ovality on load distribution and enhance the bearing’s fatigue life. This study provides a theoretical reference for the design of high-reliability slewing bearings for excavators. Full article

Decarbonization of the concrete industry has arisen as one of the main priorities for the construction sector in order to mitigate the negative climate impact associated with construction. The carbon emissions of concrete mainly originate from the production of cement, and it is essential to find supplementary cementitious materials (SCMs) to achieve eco-friendly construction materials. The use of tailings as SCMs could reduce the carbon footprint of concrete, as well as improve the environmental impact of waste management within the mining sector. To investigate the effects of using lead–zinc tailings as a partial replacement for ordinary Portland cement (OPC), an experimental study was conducted. Two types of lead–zinc tailings were utilized in the experiments to replace 10% and 20% of OPC. A mechanical activation method was adopted using a vibratory cup mill. The effects of activation on the tailings’ particle size distributions and mineralogy were evaluated. The results indicated that the activation was insufficient to promote the pozzolanic activity in T1 and only partially promoted it in T2. A total of 18 different tailing-based mortar (TBM) specimens were produced from the raw and activated tailings, and their flowability, setting time, and compressive strengths after 7, 28, and 90 days were evaluated. The microstructures of the specimens were analyzed using scanning electron microscopy with energy dispersive X-ray spectroscopy. No alteration of mineralogy was observed in T1 after activation; however, a reduction in muscovite was observed in T2. The TBM specimens with 10% activated tailings exhibited comparable 28-day compressive strengths to the control specimen. For the replacement level above 10%, there was a loss of compressive strength at 28 days, both for the activated and raw tailings and for both T1 and T2. Evaluation of the microstructure showed that the use of tailings caused regions in the cement matrix with high metal concentrations. Microcracks could be observed in or around such grains in several cases. The study demonstrated that 10% of OPC can be replaced by lead–zinc tailings while retaining the compressive strength of the specimens. Full article

Underground saturated jointed rock is prone to engineering geohazards under the combined effects of in situ stress and dynamic loading. A modified split Hopkinson pressure bar (SHPB) system was used to conduct dynamic loading tests on artificially fabricated saturated jointed rocks. The effects of joint matching coefficient (JMC) and confining pressure on the dynamic strength, deformation characteristics, energy evolution, and stress wave propagation of the specimens were investigated. The test results show that the dynamic compressive strength and stiffness of saturated jointed rocks increase with the increase in JMC, but the compressive strength is still lower than the typical dynamic strength range. Rock damage mainly occurs at the joint location, and the damage mode is dominated by tensile fracture. In terms of energy, the energy dissipation rate of the rock decreases with decreasing JMC and increasing confining pressure. The propagation of stress waves is mainly affected by the coupling of JMC and three-dimensional static stress, which is manifested as a transition from a rapidly changing phase to an unstable changing phase, a process accompanied by an energy distribution mechanism. These insights fill a gap in the mechanical response of saturated jointed rocks under complex loading conditions underground and help predict the risk of dynamic instability in underground engineering and mining operations. Full article

Norovirus is a major cause of acute viral gastroenteritis in humans. Molecular biology-based detection methods play a pivotal role in ensuring accurate and specific diagnosis. The inclusion of Qβ phage particles as armored positive controls in these assays can further enhance their reliability and specificity. Herein, we discuss rational design strategies to improve the stability of Qβ bacteriophage capsid proteins armored with RNA using Discovery Studio 2019 protein design software. Amino acid mutation sites were deter-mined based on changes in folding free energy differences (ΔΔGmut). These single-site mutations were subsequently evaluated using molecular dynamics simulations. Wild-type and mutant recombinant expression plasmids were constructed and transformed into Escherichia coli BL21 (DE3) for cloning and expression. The stability of Qβ virus-like particles (VLPs) was assessed using real-time fluorescence RT-qPCR. The results showed that structurally intact and uniformly distributed wild-type and single-site mutant VLPs were successfully obtained. Stability analyses indicated that at 4 °C, 25 °C, 37 °C, 45 °C, and 60 °C, the single-site mutant exhibited a significantly lower rate of degradation than the wild-type. In conclusion, rational design enables the generation of single-site mutant VLPs with enhanced stability, providing a safer and more stable standard reference material for the molecular detection of foodborne viruses. Full article

The rupture of the B-I dam at the Córrego do Feijão mine in Brumadinho, Minas Gerais, Brazil, on 25 January 2019, prompted the implementation of environmental remediation actions. Among these actions is the need for groundwater quality monitoring in the Feijão Pit (“Cava de Feijão”) area due to the disposal of tailings from dams B-I, B-IV, and B-IVA at this site. In order to assess potential impacts on groundwater, the determination of baseline values for elements of interest was proposed for ten monitoring wells installed in and around the pit, with monitoring results from 2019 to 2024, totaling 854 samples. Due to the lack of hydrochemistry data and local hydrogeological complexity of the existing aquifers within the context of the Iron Quadrangle (IQ), it was necessary to evaluate and determine individual baseline values for each monitoring well, assessing data variability and population distribution. For this purpose, the 95–95 Upper Tolerance Limit (UTL) method was applied to establish baseline values providing a robust statistical approach that encompasses 95% of observations with a 95% confidence interval as it is a widely used standard in statistics due to its practical balance between confidence and precision. This methodology proved effective and has potential for application in groundwater monitoring in areas that may present high compositional variability due to the chemical heterogeneity of the groundwater. The baseline values obtained for the main elements of interest, which are iron (Fe) and manganese (Mn), were consistent with findings from previous studies conducted in the hydrogeological units of the study area, also demonstrating that the adopted methodology was effective in identifying representative concentrations for the region. Full article

Analysis of the rock mining process using an experimental cutterhead employing milling and chipping processes is the subject of this article. Based on a bibliographic review of the energy consumption of rock mining and wear and tear of various mining tools, a stand test programme for the rock mining process using the experimental cutterhead was developed. Based on the following measured parameters—hydraulic motor supply pressure and displacement, hydraulic motor shaft speed, cutterhead web depth, cutterhead tilt angle relative to the mining direction, feed pressure in the advance cylinder, duration of each mining stages, cutterhead travel distance, angle of the cutterhead chipping part, and known physical and strength parameters of the mined rock—the following parameters were determined: cutterhead advance speed, cutterhead advancing force, cutterhead driving motor power, advancing cylinder power, and the parameters of energy consumption in the mining process, including specific energy of mining, specific energy of feed, and specific energy of cutting. The effects of cutterhead advance speed and tilt angle on the specific mining energy and the grain size distribution of the mined rock were determined. Analysis of test results enabled the development of the procedure for selecting the most favourable parameters of rock mining technology when using an experimental cutterhead. Full article

Symmetry plays a fundamental role in the evolution of mining-induced stress fields and the deformation behavior of roadway surrounding rock. To improve control of roadway deformation under strong mining-induced disturbance, this study takes the 12 Upper 301 face at Buertai Coal Mine and investigates the deformation mechanism and corresponding control methods. Based on an analysis of in situ monitoring data, the key stratum responsible for energy accumulation in the overlying strata was identified. Based on the inherent symmetry of the longwall mining layout, a symmetric predictive model of overburden key-stratum abutment pressure is established, which reveals the spatially symmetric distribution characteristics of the mining-induced stress field. The accuracy of the theoretical model was further verified through a large-scale geomechanical similarity model test, which reproduced the fracture trajectory and stress evolution law of the overburden key strata. To mitigate strong mining pressure, a targeted hydraulic fracturing control technique aimed at specific overburden horizons was proposed and verified through field testing and application. Field monitoring results indicate that roof-to-floor convergence peaked at 235 mm, and rib convergence peaked at 115 mm. Compared with sections without hydraulic fracturing control, the surrounding rock deformation was reduced by 62.3% and 69.7%, respectively, demonstrating a significant pressure relief effect. This approach effectively ensured the roadway stability and enabled safe mining operations. Full article

Severe floor heave in gate roadways under high-intensity longwall mining is primarily controlled by mining-induced stress redistribution. Abutment pressure is preferentially transferred through the coal pillar into the floor, accelerating floor instability. From the perspective of symmetry, mining disturbance breaks the original mechanical symmetry of the coal pillar–roadway system, resulting in asymmetric stress concentration and uneven floor heave. In this study, field monitoring and FLAC3D simulations were conducted for the 12 Upper 301 panel in the Buertai Coal Mine. The objectives were to quantify the sensitivity of coal-pillar loading and floor-heave response under stress redistribution, and to derive implications for pressure-relief design. Field monitoring indicates strong disturbance and large deformation: the maximum roof–floor and rib-to-rib convergences reached 1095 mm and 452 mm, respectively, accompanied by continuous growth of coal-pillar stress during mining. Numerical results show that increasing coal-pillar width enhances stress-bearing capacity and promotes a more symmetric stress distribution, thereby suppressing floor heave. In contrast, increasing the mining advance rate aggravates stress-field asymmetry and intensifies floor uplift. Greater burial depth further strengthens stress concentration and amplifies asymmetric deformation. Based on these findings, a roof-cutting pressure-relief scheme was optimized. This scheme aims to relieve and re-route the asymmetrically transmitted pillar loading. The optimal design adopts a roof-cutting length of 75 m and an angle of 30°, which reconstructs a more symmetric stress-transfer path; reduces the peak side abutment pressure to 8.72 MPa; and limits floor heave to 134.4 mm (control rate: 88.4%). Field application confirms the effectiveness of the proposed symmetry-based pressure-relief design. Full article

The high costs and time-consuming nature of space exploration missions are among the major barriers to studying deep space. The lack of samples and limited information make such studies challenging, highlighting the need for innovative solutions, including advanced data-mining techniques and tools such as geochemical modeling, as strategies for overcoming challenges in data scarcity. Geochemical modeling is a powerful tool for understanding the processes that govern the composition and distribution of elements and compounds in a system. In cosmology, space geochemical modeling could support cosmochemistry by simulating the evolution of the atmospheres, crusts, and interiors of astronomical objects and predicting the geochemical conditions of their surfaces or subsurfaces. This study uniquely focuses on the geochemical modeling of celestial bodies beyond Mars, fills a significant gap in the literature, and provides a vision of what has been done by analyzing, categorizing, and providing the critical points of these research objectives, exploring geochemical modeling aspects, and outcomes. To systematically trace the intellectual structure of this field, this study follows the PRISMA guidelines for systematic reviews. It includes a structured screening process that uses bibliographic methods to identify relevant studies. To this end, we developed the Custom Bibliometric Analyses Toolkit (CBAT), which includes modules for keyword extraction, targeted thematic mapping, and visual network representation. This toolkit enables the precise identification and analysis of relevant studies, providing a robust methodological framework for future research. Europa, Titan, and Enceladus are among the most studied celestial bodies, with spectrometry and thermodynamic models as the most prevalent methods, supported by tools such as FREZCHEM, PHREEQC, and CHNOSZ. By exploring geochemical modeling solutions, our systematic review serves to inform future exploration of distant celestial bodies and assist in ambitious questions such as habitability and the potential for extraterrestrial life in the outer solar system. Full article

Underground coal mining can induce substantial surface deformation and trigger associated geological hazards. However, the quantitative links between mining-induced deformation, stress redistribution, and the spatial pattern of landslide occurrence remain insufficiently understood, particularly in loess-covered mining regions. Taking the Hecaogou Coal Mine in the Zichang mining area of the Loess Plateau, China, as an example, this study uses a coupled framework that integrates multi-temporal Interferometric Synthetic Aperture Radar (InSAR) observations with three-dimensional FLAC3D numerical simulation. We found that surface deformation is primarily concentrated above and adjacent to the mined-out zones, with maximum cumulative deformation of −169.3 mm during March 2017 and December 2023. The stepwise excavation simulations reveal that vertical displacement and vertical compressive stress in the overlying strata increase continuously as mining advances, thereby promoting tensile–shear failure and surface subsidence, with the subsidence magnitude quantitatively increasing from 3.7 mm at 200 m depth to 162 mm at 1000 m depth. A strong agreement between InSAR-derived deformation and simulated deformation fields is demonstrated, confirming the reliability of the modeled deformation process. We also found that the landslide density exhibits a strong spatial correlation with surface deformation, with high-density zones clustering near the mined-out areas. These findings enhance our understanding of how underground coal mining reshapes surface stability and influences the spatial pattern of landslide occurrences in coal mining regions. Full article

China has made significant progress in paleontological heritage conservation. However, research and conservation efforts have predominantly focused on exquisitely preserved, movable specimens of high scientific value, leading to the relative neglect of in situ paleontological geosites which are critical for understanding fossil distribution patterns. To address this gap, this study employs a GIS approach to conduct a multifaceted spatial analysis of paleontological geosites in the BTH region as a representative case study. Our results reveal a pronounced spatiotemporal imbalance in the distribution of these geosites. Furthermore, their spatial configuration exhibits significant correlations with key physiographic factors—including elevation, stratigraphic distribution, and slope—as well as socioeconomic indicators such as population density, GDP density, and fiscal self-reliance ratio. This uneven distribution creates substantial conservation challenges, resulting in fragmented governance, a mismatch between local conservation capacities and needs, and potential biases in protection priorities toward specific regions or geological periods. In the BTH region, the distribution patterns of paleontological geosites are jointly shaped by physiographic, socioeconomic, and anthropogenic process factors. Elucidating the relationships between these drivers and the spatial distribution of geosites constitutes a critical foundation for advancing their scientific conservation and sustainable management. Drawing on broader interdisciplinary insights, currently peripheral paleontological heritage can be further transformed into strategic and sustainable resources. Full article

Contamination of drinking water by potentially toxic elements (PTEs) remains a critical public-health concern in Uganda. This systematic review compiled and harmonized quantitative concentrations (mg/L) for key PTEs, lead (Pb), cadmium (Cd), arsenic (As), chromium (Cr), mercury (Hg), copper (Cu), zinc (Zn), nickel (Ni), cobalt (Co), manganese (Mn), and iron (Fe), across various potable and informal water sources used for drinking, including municipal tap water, boreholes, protected and unprotected springs, wells, rainwater, packaged drinking water, rivers, lakes, and wetlands. A comprehensive search of different databases and key institutional repositories yielded 715 records; after screening and eligibility assessment, 161 studies met the inclusion criteria, and were retained for final synthesis. Reported PTE concentrations frequently exceeded WHO and UNBS drinking water guidelines, with Pb up to 8.2 mg/L, Cd up to 1.4 mg/L, As up to 25.2 mg/L, Cr up to 148 mg/L, Fe up to 67.3 mg/L, and Mn up to 3.75 mg/L, particularly in high-risk zones such as Rwakaiha Wetland, Kasese mining affected catchments, and Kampala’s urban springs and drainage corridors. These hotspots are largely influenced by mining activities, industrial discharges, agricultural runoff, and corrosion of aging water distribution infrastructure, while natural geological conditions contribute to elevated background Fe and Mn in several regions. The review highlights associated health implications, including neurological damage, renal impairment, and cancer risks from chronic exposure, and identifies gaps in regulatory enforcement and routine monitoring. It concludes with practical recommendations, including stricter effluent control, expansion of low-cost adsorption and filtration options at household and community level, and targeted upgrades to water-treatment and distribution systems to promote safe-water access and support Uganda’s progress toward Sustainable Development Goal 6. Full article

To address the technical challenge where traditional high-pressure, large-flow emulsion pump stations cannot adapt to the drastic flow rate changes in hydraulic supports due to the fixed displacement of their quantitative pumps—leading to frequent system unloading, severe impacts, and damage—this study proposes an intelligent flow control method based on the digital flow distribution principle for actively perceiving and matching support demands. Building on this method, a compact, electro-hydraulically separated prototype with stepless flow regulation was developed. The system integrates high-speed switching solenoid valves, a piston push rod, a plunger pump, sensors, and a controller. By monitoring piston position in real time, the controller employs an optimized combined regulation strategy that integrates adjustable duty cycles across single, dual, and multiple cycles. This dynamically adjusts the switching timing of the pilot solenoid valve, thereby precisely controlling the closure of the inlet valve. As a result, part of the fluid can return to the suction line during the compression phase, fundamentally achieving accurate and smooth matching between the pump output flow and support demand, while significantly reducing system fluctuations and impacts. This research adopts a combined approach of co-simulation and experimental validation to deeply investigate the dynamic coupling relationship between the piston’s extreme position and delayed valve closure. It further establishes a comprehensive dynamic coupling model covering the response of the pilot valve, actuator motion, and backflow control characteristics. By analyzing key parameters such as reset spring stiffness, piston cylinder diameter, and actuator load, the system reliability is optimized. Evaluation of the backflow strategy and delay phase verifies the effectiveness of the multi-mode composite regulation strategy based on digital displacement pump technology, which extends the effective flow range of the pump to 20–100% of its rated flow. Experimental results show that the system achieves a flow regulation range of 83% under load and 57% without load, with energy efficiency improved by 15–20% due to a significant reduction in overflow losses. Compared with traditional unloading methods, this approach demonstrates markedly higher control precision and stability, with substantial reductions in both flow root mean square error (53.4 L/min vs. 357.2 L/min) and fluctuation amplitude (±3.5 L/min vs. ±12.8 L/min). The system can intelligently respond to support conditions, providing high pressure with small flow during the lowering stage and low pressure with large flow during the lifting stage, effectively achieving on-demand and precise supply of dynamic flow and pressure. The proposed “demand feedforward–flow coordination” control architecture, the innovative electro-hydraulically separated structure, and the multi-cycle optimized regulation strategy collectively provide a practical and feasible solution for upgrading the fluid supply system in fully mechanized mining faces toward fast response, high energy efficiency, and intelligent operation. Full article

To investigate the deformation behavior of corrugated steel pipe arch bridges subjected to differential foundation settlement, this study examines a ten-span continuous corrugated steel pipe arch bridge as the engineering background. A one-year field monitoring program was conducted to record the settlement of each span, and the spatial distribution pattern, annual cumulative settlement, and settlement growth rate were evaluated. Numerical analyses were then performed to compare the deformation response of the bridge under ideal foundation conditions, differential foundation settlement, and vehicle loading. Based on the numerical results, the effectiveness of a concrete lining installed inside the corrugated steel pipe was further assessed. The results show that the settlement of the side spans is significantly larger than that of the middle spans due to the differential foundation settlement in the mining area. The maximum annual cumulative settlement at the side span (span 2) reaches 21.66 mm, which is approximately 4.1 times that of the middle span (span 6). During the monitoring period, the settlement growth rate was high in the early stage (1~3 months), reaching up to 30 percent, and gradually stabilized to about 10 percent per month in the later stage. Compared with the ideal foundation condition, differential settlement increases the pipe stress by a factor of 3.4 and amplifies the deformation by a factor of 9.1. Vehicle loading has a pronounced effect on the deformation of the pipe crown, increasing the settlement by approximately 9 percent, while its influence on the pipe invert is relatively small, with an increase of about 4 percent. Installing a 100 mm thick concrete lining inside the corrugated steel pipe has limited influence on the overall load-carrying behavior but reduces the deformation by 10~20 percent. This reinforcement method is suitable for applications in existing bridges. Full article