Search Results (876)

Aramid fiber reinforced polymers (AFRPs) are widely used in aerospace and defense structures because of their high specific strength, impact resistance, and damage tolerance. However, severe burr formation during machining remains a major obstacle to achieving high surface integrity and dimensional accuracy. In particular, the mechanism by which tool edge radius affects burr formation in AFRP cutting has not yet been clarified quantitatively. To address this issue, this study develops an analytical model for the orthogonal cutting of AFRPs to reveal the burr formation mechanism associated with tool edge radius. The model, established on the basis of contact mechanics and fracture theory, predicts fiber deflection, cutting force evolution, fracture behavior, and burr length under different contact and boundary conditions. The results show that tool edge radius governs burr formation through a contact–state transition mechanism. When the edge radius is below a critical threshold, localized point-contact-like interaction promotes stress concentration and fiber fracture, leading to relatively clean material removal. When the edge radius exceeds this threshold, the interaction evolves toward extended contact and sliding, which suppresses complete fiber fracture and results in pronounced burr retention. Experimentally, increasing the edge radius from 5.6 μm to 110.3 μm increased the maximum burr height from 3.19 μm to 83.58 μm, corresponding to an increase of approximately 2520%. The predicted burr evolution agrees well with the experimental observations in both trend and characteristic magnitude. This study provides a mechanistic and predictive understanding of burr formation in AFRP machining and offers practical guidance for cutting edge preparation, tool wear control, and process optimization in high-quality composite machining. Full article

Industrial hemp (Cannabis sativa L.) harvesting for grain represents a critical technological bottleneck in the modern supply chain, driven by a fundamental conflict between the plant’s resilient morphology and standard agricultural machinery. This review provides an analytical synthesis of harvesting methodologies, evaluating their performance against specific biological constraints such as extreme plant height (up to 4.5 m), high tensile fiber strength, and indeterminate ripening. Data synthesis reveals that hemp cutting is approximately 80 times more energy-intensive than for traditional forage crops, requiring an average maximum force of 243 N per stem. Comparative analysis demonstrates that while conventional whole-plant harvesting faces seed losses ranging from 26% to 46%, selective systems like specialized panicle mowers reduce these losses to nearly 2 kg·ha⁻¹ by targeting only the mature inflorescences. To ensure seed integrity and operational stability, the review identifies concrete technological priorities: the use of abrasion-resistant alloys for cutting edges, the implementation of non-binding shaft shielding (e.g., ABS piping), and a 40–50% reduction in threshing cylinder speeds compared to cereal settings. Future advancements must focus on specialized, high-clearance selective machinery and adaptive control systems to reconcile hemp’s unique physiology with industrial-scale efficiency. Full article

Guiding structural failure toward a prescribed failure mechanism can significantly mitigate the risk of collapse under extreme seismic action. However, quantitative criteria for identifying the target failure mechanism remain underdeveloped. To fill the gap, this work proposes a general framework for determining a target failure mechanism in frame structures. First, a generalized lateral failure mechanism is introduced and rigorously defined. Second, a topology-based search algorithm is developed to identify the minimal cut sets of failure mechanisms. On this basis, a two-stage evaluation procedure is proposed to identify the governing failure mechanism via the upper-bound theorem and subsequently determine the target failure mechanism through a max–min capacity criterion. Finally, 36 case studies covering three frame topologies are investigated. Results indicate that: (1) the selection of the target mechanism should be case-specific rather than determined solely by engineering intuition; (2) the target mechanism is controlled by structural topology, design constraints, and inter-story height distribution; and (3) across all topologies, increasing γ⁽⁰⁾ consistently shifts the selected target failure mechanisms toward configurations with a lower proportion of column hinges. Numerical pushover validation further confirms the mechanical consistency of the proposed framework, with the ultimate capacities obtained from the proposed method agreeing well with nonlinear simulation results. The proposed framework provides a theoretical basis and practical tools for failure-mechanism-based seismic design, with implications for improving structural safety and reliability. Full article

Background: Overweight and obesity are emerging public health concerns among young adults. However, evidence on associated sociodemographic, dietary, and lifestyle factors among young industrial workers in low- and middle-income countries remains limited. This study aimed to identify factors associated with overweight and obesity among Vietnamese young industrial workers aged 18–30 years. Methods: A cross-sectional study was conducted among 2295 young industrial workers (55.6% men and 44.4% women) recruited from factories and industrial zones in three geographic regions of Vietnam. Sociodemographic characteristics, dietary habits, lifestyle behaviors, and physical activity were assessed using a structured questionnaire. Body mass index (BMI) was calculated from self-reported height and weight and classified using WHO Western Pacific Region (WPRO) cut-offs; overweight/obesity was defined as BMI ≥ 23.0 kg/m². Physical activity was assessed using the International Physical Activity Questionnaire—Long Form (IPAQ-LF) and categorized by total MET-min/week according to IPAQ scoring guidelines. Logistic regression analyses were performed to estimate crude and adjusted odds ratios (ORs) with 95% confidence intervals (CIs). Results: Overall, 10.4% of participants were overweight (BMI 23.0–24.9 kg/m²) and 7.0% were obese (BMI ≥ 25.0 kg/m²), yielding a combined prevalence of 17.4%. After multivariable adjustment, increasing age (aOR = 1.15; 95% CI: 1.10–1.20), male sex (aOR = 2.10; 95% CI: 1.59–2.76), and regular alcohol consumption (aOR = 1.37; 95% CI: 1.04–1.81) were independently associated with higher odds of overweight/obesity, while residence in the Southern region was inversely associated (aOR = 0.57; 95% CI: 0.42–0.76). High total physical activity (vs. low activity) was positively associated with overweight/obesity, whereas moderate physical activity was not independently associated. Other dietary behaviors were not significantly associated after adjustment. Conclusions: Among Vietnamese young industrial workers, overweight and obesity were associated with age, sex, alcohol consumption, and geographic region. The observed association with high total physical activity likely reflects the occupational context of physical activity in this population, highlighting the importance of distinguishing between occupational and leisure time physical activity when interpreting physical activity obesity relationships. These findings underscore the relevance of early, workplace relevant prevention strategies targeting modifiable behaviors, particularly alcohol use. Full article

The bottom water of the Shizhouji Formation tight sandstone reservoir in the Tazhong Shun 9 well area is developed. General fracturing faces the problem of excessive extension of hydraulic fractures and easy communication with water layers. A true triaxial fracturing physical simulation experiment was conducted on the sandstone and mudstone outcrops of the same layer to explore the expansion laws of hydraulic fractures in the tight sandstone reservoir and consider the influence of mudstone interlayers, horizontal stress difference, fracturing fluid flow rate, and viscosity. The mechanism of multi-cluster fractures/artificial fractures penetrating through the layers was revealed. The research results show that the existence of mudstone interlayers greatly increases the complexity of fractures, from 1.88 to 2.96, an increase of 57%. When there is a mudstone interlayer in the rock, the fracturing process is prone to open weak planes, hindering the expansion of hydraulic fractures. The hydraulic fractures of Sample No. 4 were cut off four times and penetrated through the layers once. The larger the flow rate, the greater the complexity of hydraulic fractures, and the easier the fractures penetrate through the layers. The fractures with a large flow rate (200 mL/min) were cut off three times, and the stress difference was larger, the hydraulic fractures tended to be simple, and the penetration through the layers was zero times at a high-level stress difference (18 MPa); the greater the viscosity, the greater the fracture pressure, and the complexity of fractures first increased and then decreased; the greater the viscosity, the more easily the hydraulic fractures penetrate through the layers, with low viscosity cutting off three times, medium viscosity cutting off four times, and high viscosity cutting off five times. Therefore, considering the limitation requirements of the on-site fracturing on the extension of fracture height, it is recommended that the on-site fracturing construction flow rate be 6 m³/min, and the fracturing fluid viscosity be 10 mPa·s. Full article

Lisianthus [Eustoma grandiflorum (Raf.) Shinners] is among the 10 most produced and marketed cut flowers in the world. However, its slow growth represents a challenge for its production. This study evaluated the efficiency of rhizobacterial strains in vegetative growth and nutrient acquisition in lisianthus plants. Freshly germinated seeds of lisianthus cv. Mariachi Blue Double were used. Seven rhizobacterial strains and two controls (sterile distilled water and nutrient broth) were evaluated in a completely randomized design. Replication varied among treatments and variables: shoot growth traits were assessed on 10–12 plants per treatment, root biomass on a destructive subsample of six plants per treatment and shoot nutrient contents on four composite samples per treatment. Measurements taken 149 days after sowing showed that plants inoculated with the strains Acinetobacter vivianii C48, Achromobacter xylosoxidans C56, and Arthrobacter pokkalii JLB4 had greater height, leaf area, leaf number, and fresh and dry biomass, both aerial and in the root. These strains also enhanced N and P uptake in shoot tissues. In contrast, the Bacillus pumilus strain R44 significantly decreased height and leaf number. The results suggest that strains C48, C56 and JLB4 can stimulate nutrition, accelerate plant growth, and shorten the vegetative phase in lisianthus. Full article

The proper selection of surface topography (ST) parameters is crucial for ensuring the effective performance of machine components, including their wear and corrosion resistance. In the literature, research on the ST of hardened stainless steels (SSs) after finish turning using cubic boron nitride (CBN) inserts, as well as comparisons with cemented carbide (CC) inserts depending on cutting parameters, is still limited. In this study, the ST of X20Cr13 martensitic hardened SS under dry finish turning with various cutting speeds and feed rates was investigated. Experiments were conducted using a CNC lathe with CBN and CC inserts. A Sensofar S Neox 3D optical profilometer was employed to characterize the ST features, including height surface roughness (SR) parameters, SR profiles, and 2D and 3D surface images. The Parameter Space Investigation method was used to design the experimental plan. For both CBN and CC inserts, the feed rate was the dominant factor influencing the overall SR, described by the Sa and Sq parameters. The extreme parameters Sp, Sv, and Sz were determined by the relationship between feed rate and cutting speed. With appropriately selected turning parameters, it is possible to obtain low Sa values (0.4–0.6 µm), which can eliminate the need for grinding operations. CBN inserts ensured a more regular shape of the ST, while CC inserts contributed to a wavy surface characteristic, associated with more intense plastic deformation. However, low Sa values may be accompanied by isolated peaks, indicating that this parameter does not always fully reflect the presence of extreme micro-irregularities. On the machined surfaces, adhesive bonds of chips and cutting tool material were observed. In addition, micro-scratches were registered for CBN inserts, and a side flow phenomenon for CC inserts. The results confirm that dry turning of hardened SSs can be effectively performed using both CC and CBN inserts. Full article

Intraspecific phenotypic diversity in clonally propagated crops is frequently constrained by narrow domestication histories and the widespread use of a limited number of elite cultivars. In Stevia rebaudiana, commercial production has largely centred on cv. ‘Morita II’, raising concerns about reduced diversity and adaptive potential. This study characterised and structured phenotypic diversity within a segregating population derived from ‘Morita II’ under tropical field conditions. Eighty-six progeny-derived genotypes (clonally propagated) plus the commercial control (87 genotypes total) were evaluated using 25 agromorphological descriptors (qualitative and quantitative). Quantitative traits showed broad variation, including plant height (28.26–119.50 cm) and dry yield rate (0.94–28.55 g plant⁻¹). Multivariate analyses of mixed descriptors (PCA and hierarchical clustering based on Gower distance) identified plant architecture, vegetative growth, and phenology as the main sources of differentiation. The first two principal components explained 19.65% and 12.58% of total phenotypic variance, respectively (32.23% cumulative). Hierarchical clustering (UPGMA; dissimilarity cut-off = 0.25) resolved four phenotypic groups (GI–GIV) with sizes n = 3, 1, 66, and 17, respectively, enabling the definition of contrasting ideotype candidates based on recurrent trait combinations. These results provide a quantitative baseline for phenotypic structuring, prioritization of materials for further evaluation, and management of clonal stevia collections in tropical production systems. These ideotype candidates should be considered preliminary until validated across environments and linked to chemical quality traits. Full article

To address the challenges of water hazard control in the thick water-rich sandstone aquifer of the roof under monoclinal structure conditions at Panel 110504 of Wangwa Coal Mine, as well as the problems of excessive ineffective drainage and high cost associated with the traditional full-face pre-drainage method, a study on the coordinated technology of mining progress and roof water drainage was carried out. By analyzing the geological and hydrogeological conditions of the panel, it was determined that the height of the water-conducting fracture zone reaches 228 m, which has penetrated the Yan’an Formation and entered the sandstone aquifer of the Zhiluo Formation, forming a unified composite water-filling source from the two aquifers. Based on calculations using the Theis equation and field drainage tests, the stable drainage time was determined to be 95 d and the advance drainage distance 300 m. Accordingly, a coordinated technical scheme of “sectional drainage while mining” was proposed, optimizing the layout parameters of drainage boreholes and the division of drainage sections. Field application results show that this technology reduced the average water inflow of the panel by 255.94 m³/h compared with the traditional mode, cumulatively saved 5.1413 million m³ of drainage water, cut drainage costs by 20.5652 million CNY, and no water hazard occurred. The research results can provide a technical reference for mining coal seams with water-rich roof under similar monoclinal structure conditions. Full article

Deep underground coal mines are severely threatened by dynamic coal rock disasters such as mine pressure bumps and coal and gas outbursts, and coal seam pressure relief technology is widely recognized as the key measure for mitigating these hazards. To investigate the pressure relief effect of coal seam slot cutting using a diamond beaded wire saw, a combined strategy integrating physical similarity simulation and numerical simulation was applied. The stress distribution characteristics of the coal and rock mass during the wire saw cutting procedure were evaluated, and the influence of beaded wire saw diameter on pressure relief efficiency was further examined. (1) Wire saw cutting can substantially decrease the vertical stress within the coal seam; the average pressure relief rate above the slot can reach as high as 61.70%, and the pressure relief effect is clearly stronger than that below the slot. (2) After slot cutting along the roadway, the fully pressure-relieved zone displays an annular spatial pattern; the pressure relief effect at both ends of the slot and around the roadway is particularly evident, whereas the pressure relief degree in the middle part is comparatively low because of the closure effect. (3) Slot closure causes notable changes in the pressure relief state. Before closure, the pressure relief effect above the slot remains satisfactory; after closure, stress recovery appears in the middle part, but the overall pressure relief rate still stays above 10%, and the pressure relief rate at both ends of the slot and near the roadway exceeds 50%, with the fully pressure-relieved zone still maintaining an annular distribution. (4) A positive correlation exists between the wire saw diameter and the height of the fully pressure-relieved zone. For every 0.5 cm increase in diameter, the height of the fully pressure-relieved zone rises by an average of 0.6 m. When the wire saw diameter reaches 3 cm, the full-thickness and adequate pressure relief of a 3 m thick coal seam can be realized. Full article

Background/Objectives: Growth monitoring and screening are vital indicators for child wellness. Controversy exists regarding the use of national versus international growth charts for school-going children. This study investigated the suitability of existing global references, considering the influence of age, gender, and socioeconomic status (SES), and the specific growth patterns across multiple anthropometric health indicators (AHIs). Methods: A total of 349 children (boys = 165, girls = 184, low SES = 201, high SES = 148) were measured longitudinally at ages 6, 9, and 12 years while attending primary school. AHI included stature, body mass, body mass index (BMI), body fat percentage (BFP), skinfold thickness, skeletal muscle, and waist circumference (WC). Results: Three-way interaction effects were found for age, gender, and SES on WC and skeletal muscle (p = 0.05). Several two-way interactions emerged for age and gender (height, BMI, skeletal muscle; p < 0.01), as well as age and SES (height, BMI, skeletal muscle; p < 0.01) and gender and SES (height, skeletal muscle, WC, p < 0.05). Cut-points for height, body mass, and BMI at the median, compared to universal standards, indicate that the total group fell at, or slightly above, World Health Organization (WHO) standards. The low SES group aligned with WHO standards, whereas the high SES group trended above the reference values at most points. Conclusions: The WHO growth standards are suitable for general monitoring in South African children aged 6–12 years but provide limited context-specific interpretation across age, gender, and socioeconomic backgrounds. National age-, gender-, and SES-specific growth references, incorporating additional anthropometric indicators, are needed to support locally relevant screening. Full article

Injection-molding purges are heterogeneous, bulky residues whose uncertain composition and irregular geometry hinder direct reinsertion, making cold shredding costly and maintenance-intensive. This work develops a low-infrastructure solar-assisted pre-processing route using a PMMA Fresnel lens to induce controlled sub-onset softening and enable clean shear cutting without destructive thermal histories. The sub-onset softening is here defined into a viscoelastically active range (at or above T_g for the amorphous phase) while remaining below the melting onset (T_m, onset) and below the onset of thermal degradation (T_d, onset). The station was engineered via QFD and risk-oriented design tools, while a weighted Pugh matrix selected shear cutting over saw-based alternatives. A screening factorial DOE showed that lens height, angle, and their interaction significantly govern focal-spot diameter and receiver temperature, yielding linear relations for conservative set-point selection. Receiver benchmarking further indicated that copper reaches substantially higher temperatures than graphite under identical exposure conditions, supporting copper as the simplest, rapid-heating receiver. Under DOE-calibrated operation, tear-free shear cutting was achieved across representative purge families (PP–ABS, PC–ABS–PP, PA66, PA66-filler, and POM) without forced convection. From a recycling and waste-management perspective, the approach converts bulky purge scrap into mill-compatible feedstock with reduced mechanical resistance, lowering tool wear and fines generation, accelerating downsizing, and limiting stockpiling that elevates combustible-inventory fire risk. Overall, the proposed DOE-calibrated, operator-friendly framework improves recycling feasibility by enabling safer handling, more stable preprocessing throughput, and reduced reliance on disposal or long-term storage for heterogeneous industrial purges. Full article

To overcome the limitations of Orthonormal Basis Function (OBF) methods in magnetic anomaly detection, including high false alarm rates and ambiguous target localization due to background noise, this paper introduces a high-confidence detection algorithm based on hierarchical clustering with an optimal cut height. The core of our approach is a theoretically derived optimal cut height, which is calculated from a physical model of the magnetic dipole’s vertical gradient field. This model establishes the implicit functional relationship between the effective detection range and key parameters, including magnetic moment orientation, geomagnetic inclination, and sensor height. The calculated optimal cut height serves as the critical criterion in a complete-linkage hierarchical clustering algorithm, which processes the alarm point clouds generated by a preliminary Greatest-of Cell-Averaging Constant False Alarm Rate (GOCA-CFAR) detector. This effectively suppresses isolated false alarms caused by background fluctuations while preserving spatially coherent alarm clusters within the target’s effective detection range, thereby significantly enhancing detection confidence. Results from both simulations and field experiments validate the efficacy of the proposed algorithm, demonstrating its superior capability to reliably discriminate genuine targets from false alarms compared to traditional one-dimensional CFAR detection. Full article

Soil and water bioengineering (SWBE) is increasingly used as a nature-based solution for riverbank stabilization and riparian restoration, yet its effectiveness in tropical environments remains constrained by limited field-based evidence of species performance under hydrological disturbance. This study evaluated the establishment success and ecological effectiveness of four native riparian species (Croton urucurana Baill., Sesbania virgata (Cav.) Pers., Iochroma arborescens (L.) J.M.H.Shaw, and Gymnanthes schottiana Müll.Arg.) installed as live cuttings on a riprap structure exposed to recurrent flooding along the Paraopeba River, Brazil. A total of 160 live cuttings were monitored over a 33-month establishment period to assess survival, structural development, spontaneous vegetation recruitment, and changes in soil chemical properties and soil organic carbon stocks. Flooding acted as a dominant ecological filter, causing substantial early mortality, with overall survival declining sharply during a 70-day inundation period that included 58 consecutive days of submergence. Croton urucurana exhibited the highest survival and structural development, reaching median heights exceeding 5 m and cumulative shoot diameters greater than 100 mm after 33 months, whereas Gymnanthes schottiana showed complete mortality within the first year. Vegetation establishment facilitated spontaneous recruitment of native woody species, with 22 individuals recorded in planted sections compared to only 3 in adjacent non-planted areas. Soil organic carbon stocks increased from 38.9 to 60.6 Mg C ha⁻¹ in the 0–40 cm soil profile, indicating rapid soil development. These results demonstrate that SWBE interventions can simultaneously promote riverbank stabilization, vegetation recovery, and soil carbon accumulation. By providing quantitative field-based evidence under realistic hydrological disturbance conditions, this study advances the understanding of species selection and the ecological effectiveness of SWBE interventions in tropical riparian ecosystems. Full article

Longwall top coal caving is one of the most effective methods for extracting steeply inclined and ultra-thick coal seams. To investigate the influence of caving ratio (the proportion between mining height and top coal thickness) on top coal recovery behavior and ground pressure characteristics, this study employs both the Particle Flow Code (PFC) discrete element method and a coupled FLAC^3D–PFC^3D numerical simulation approach. The effects of different caving ratios (1:3, 1:3.2, and 1:3.4) on the top coal recovery ratio, stress distribution, and gangue accumulation characteristics were analyzed. The results show that the caving ratio has a significant impact on top coal recovery. At a caving ratio of 1:3.2, adopting a two-cut-one-cave interval resulted in a top coal recovery ratio as high as 94.8%. A stress-relief zone with an arch-like distribution formed above the goaf, while a stress concentration zone developed ahead of the coal wall, where the coal–rock mass underwent compression and failure. The roof displacement exhibited an arch-shaped distribution, while the floor displacement was asymmetrical, with greater heaving observed at the lower end. As the working face advanced, the horizontal development of the plastic zone expanded rapidly, while the vertical extent changed only slightly. Throughout the caving process, the top coal demonstrated favorable caving behavior with good flowability and accumulation characteristics. These findings provide theoretical support for achieving high mining recovery in thick coal seam operations and offer practical guidance for optimizing caving process parameters in practice. Full article