Search Results (3,348)

It is widely recognized that grain variability affects the physical and engineering properties of cowpea and maize varieties. Understanding the effects is vital for designing a dehulling machine that can yield better performance. The physical and engineering properties of nine cowpea varieties and a local maize variety were determined to provide essential data for the design of dehulling and processing equipment. Standard laboratory methods reported in the literature were used to analyze the grains. The study reveals that the physical and engineering properties of nine cowpea and maize varieties varied considerably (p < 0.05). The mean values of moisture content % ranged from 10.06 to 13.81%, length ranged from 7.11 to 11.44 mm, width ranged from 5.65 to 10.28 mm, thickness ranged from 4.60 to 6.73 mm, and thousand-grain weight ranged from 100 to 364 g. Da ranged from 5.79 to 8.89 mm, Dg ranged from 5.66 to 8.59 mm, sphericity ranged from 0.73 to 0.86, surface area ranged from 101.38 to 233.75 mm², and volume ranged from 97.05 to 339.82 mm³. Furthermore, the COF on stainless steel ranged from 0.30 to 0.37, the angle of repose ranged from 20.03 to 30.33°, the bulk density ranged from 688.00 to 814.67 kg/m³, the true density ranged from 1079.91 to 1282.61 kg/m³, and the porosity % ranged from 60.53 to 67.46%. Lastly, grain hardness ranged from 56.27 to 267.91 N, grain compressive energy ranged from 80.91 to 664 mJ, grain stiffness ranged from 6.48 to 26.13 N/mm, seed coat–cotyledon/pericarp–endosperm stickiness force ranged from 0.04 to 0.10 N, Adhesiveness (force to overcome stickiness) ranged from 0.08 to 93.42 N · mm, and fracturability ranged from 56.27 to 267.91 N. These results offer a comprehensive engineering database for the design and optimization of dehulling and post-harvest processing equipment. Full article

Seismic hazards in underground coal mines are frequently triggered by geological anomalies and residual coal pillars, posing severe threats to safe mining. A protected seam longwall in a Chinese coal mine was used as a case to analyse the seismic clustering characteristics under the combined influence of the B4 anticline and a 30-m-wide overlying residual chain pillar. A simulation-testing-based source locating accuracy (STSLA) method was used to study the vector characteristics of seismic location errors in the longwall. A new seismic clustering index, the Number of Possible Clustered Events (NPCE), was proposed to quantify fracture connectivity in the coal-rock mass while reducing the influence of locating errors. The spatial–temporal evolution of NPCE, seismic event frequency, and energy magnitude was compared. Results show that NPCE exhibits a strong positive correlation with imminent high-energy seismic events and outperforms conventional indicators in recall rate and overall early-warning performance. The confusion matrix method demonstrates that NPCE achieves a better balance between precision and recall, especially at high pre-warning thresholds. NPCE = 0.7 is determined as the optimal threshold for seismic hazard risk identification. The proposed method provides a reliable approach for seismic-data-based seismic hazard early warning. Full article

Amid the global transition to low-carbon energy systems, unconventional oil and gas resources play a key role in ensuring energy security. Hydraulic fracturing is a central technology for unconventional resource development, but it may also induce seismicity. This study investigates energy release and induced seismicity during hydraulic fracturing in naturally fractured media. A fully coupled hydro-mechanical-damage (HMD) model combined with a discrete fracture network (DFN) is developed to represent natural fractures in shale reservoirs. By incorporating frictional contact and shear slip, the model simulates tensile propagation of hydraulic fractures and shear slip of natural fractures. Parameter sensitivity analyses are conducted for natural fracture characteristics, differential stress, elastic modulus, and injection rate. The energy release of shear slip and tensile propagation is compared based on total seismic moment. Results show that the seismic moment generated by natural fracture shear slip is several orders of magnitude higher than that from tensile propagation, indicating that shear slip is the dominant energy release mechanism. Increasing the number and length of natural fractures enhances fracture-network connectivity and pressure diffusion, making natural fractures more prone to shear instability. Higher differential stress, elastic modulus, and injection rate may further promote slip-induced energy release and elevate induced seismic risk. These findings provide a theoretical basis for seismic risk assessment and parameter optimization in hydraulic fracturing. Full article

The geometric characteristics of these fractures have a substantial influence on the mechanical and energy properties of heterogeneous rocks. This study calibrated the experimental results using the finite-discrete element method (FDEM). An orthogonal design was employed to investigate the effects of the homogeneity coefficient, fracture angle, fracture length, and fracture aperture on the mechanical and energy characteristics of fractured sandstone. The main factors influencing the mechanical properties and energy characteristics of rocks were explored through multi-factor correlation analysis. The effects of fracture geometric features and heterogeneity on the mechanical properties and energy characteristics of rocks were analyzed by single-factor analysis. A regression model between peak stress and fracture geometric features was established. The results show the following: The homogeneity coefficient and fracture length have a significant impact on the elastic modulus of fractured sandstone. The fracture angle and fracture length have a significant influence on the peak strain, elastic strain energy and total energy of fractured sandstone. The fracture angle, fracture length and homogeneity coefficient have a significant effect on the peak stress of fractured sandstone. The elastic modulus and peak stress show a logarithmic relationship with the homogeneity coefficient, while the elastic strain energy and total energy have a logarithmic relationship with the crack length. The peak strain and peak stress have a quadratic polynomial relationship with the crack angle, and the elastic strain energy and total energy also have a quadratic polynomial relationship with the crack angle. The elastic modulus, peak strain, and peak stress have a logarithmic relationship with the crack length. The predicted values of peak stress and numerical calculation errors of fractured rocks mainly range from 0.07% to 7.76%, with an average error of 2.58%. Both the peak stress prediction values and the numerical calculation results show a “U”-shaped change trend, first decreasing and then increasing with the increase in the fracture angle. This study investigates the influence of fracture geometric characteristics on the mechanical and energy characteristics of heterogeneous rocks, which is of great significance for the stability control of fractured rock masses and the optimization of underground engineering parameters. The core challenge for future research lies in revealing the intrinsic connection among fracture geometric features, rock mass heterogeneity, and multi-field coupling effects to meet the complex engineering demands of deep mining, thereby serving the safe production and disaster prevention of deep mines. Full article

Despite the low thermal conductivity that characterizes the mechanical behavior of cementitious composites like concrete, high temperatures acting for long periods could have devastating effects on the overall integrity and stability of structures. Such damage encompasses not only the structural but also the material level, manifested as a degradation of the strength and stiffness properties together with increasing porosity and the consequent cohesion loss. Adding fibers to the cementitious matrix is a strategy that increases the fire resistance of structures, improving the fracture energy release capacity beyond the peak strength. This fact has been experimentally demonstrated in numerous publications and requires the development of advanced computational constitutive models with the aim of predicting the evolution of both elastic properties and failure behavior in fiber-reinforced concrete. In this work, a temperature-dependent, thermodynamically consistent microplane material model based on the smeared crack approach is developed to simulate the mechanical behavior of preheated steel fiber-reinforced concrete (SFRC) under residual conditions. The influence of high temperatures on the material response is evaluated in terms of stress versus crack opening displacement or crack slip curves, whereas the failure analysis in the form of discontinuous bifurcation is addressed by means of numerical analysis of the acoustic tensor, identifying the critical orientation for varying temperature levels, material properties and boundary conditions. Full article

Additive manufacturing using vat photopolymerization (VPP) resin materials has gained attention for fabricating dental prostheses; however, the effects of material type and build angle on their properties remain unclear. We compared the mechanical properties of two filler-containing VPP hybrid resins, SprintRay Ceramic Crown (CC) and OnX Tough 2 (OT), with those of a conventional polymethyl methacrylate (PMMA) disc material, and evaluated the influence of build angle on surface characteristics, dimensional accuracy, and mechanical performance. Specimens were fabricated using a DLP system at build angles of 0°, 45°, and 90°. Vickers hardness, surface morphology and roughness, dimensional deviations, flexural strength, elastic modulus, and fracture energy were assessed according to relevant standards. CC exhibited significantly higher hardness and elastic modulus than PMMA and OT, whereas OT showed the highest fracture energy. Surface morphology and roughness were strongly affected by build angle, with 45° producing distinct periodic patterns and increased roughness. Dimensional evaluation revealed a tendency toward overbuilding, particularly in the vertical direction at 45°. Flexural properties were also influenced by build angle, with 45° generally providing favorable performance. Both material composition and build angle affect VPP-fabricated dental resin performance, highlighting the importance of appropriate material and processing selection for clinical applications. Full article

Background: Acute compartment syndrome (ACS) is a limb-threatening surgical emergency most commonly associated with fractures or high-energy trauma. Non-fracture-related ACS in athletes is uncommon and may lead to delayed diagnosis. Repetitive blunt trauma during combat sports has rarely been described as a potential mechanism. Case Methods: The case concerns a 21-year-old elite-level kickboxing athlete who developed acute compartment syndrome of the left lower leg following repeated calf kicks sustained during sparring. The patient presented with rapidly progressive calf pain, swelling, compartment firmness, paresthesias and weight bearing difficulties. CT angiography demonstrated diffuse edema of the posterior compartments associated with a large intramuscular soleus hematoma without active arterial bleeding. Results: In view of the severity of the symptoms and the characteristic clinical presentation, an emergency fasciotomy was performed in operating room. Progressive closure was achieved using the vessel loop shoelace technique, allowing gradual tension-free closure. Wound healing progressed without infection, and physiotherapy was introduced with joint mobilization. The patient achieved full functional recovery after 6 months. Conclusions: This case illustrates an atypical etiology of ACS—repetitive targeted calf strikes—and underscores the importance of early recognition even in the absence of fracture or major trauma. Clinical vigilance remains paramount, and prompt surgical intervention is critical to prevent irreversible muscle and nerve damage. Awareness of such mechanisms is particularly relevant for clinicians managing athletes in combat sports. To our knowledge, this is the first documented case of ACS secondary to repeated calf kicks in kickboxing. Full article

Background/Objectives: Distal femoral physeal fractures are rare and particularly uncommon in very young patients, as they typically require a significant amount of kinetic energy. They carry a high risk of premature physeal closure and later growth disturbance. We aimed to describe the management and long-term outcome of an open distal femoral physeal fracture in a 6-year-old child. Methods: We report a previously healthy 6-year-old child sustained an open distal femoral physeal fracture in an electric scooter–motor vehicle collision. Emergency treatment included trauma assessment, resuscitation, intravenous cefazolin, urgent irrigation and debridement, open reduction, crossed smooth Kirschner-wire fixation, and immobilization. Long-term follow-up included growth prediction using the multiplier method. Results: The injury was classified intraoperatively as a Salter–Harris type I distal femoral physeal fracture. Despite timely surgical treatment, progressive limb-length discrepancy developed, increasing from 1.3 cm at 10 months to 6.5 cm over 5 years. Growth prediction estimated a final discrepancy of 7.32 cm at skeletal maturity, and contralateral distal femoral epiphysiodesis was performed. The literature confirms that displaced high-energy distal femoral physeal injuries in younger children carry a substantial risk of premature physeal closure and later corrective surgery. Conclusions: Open high-energy distal femoral physeal fractures in young children are limb-growth-threatening injuries. This case demonstrates that satisfactory initial fracture management does not eliminate the risk of later premature physeal closure, and that clinically important discrepancy evolves gradually over several years. Long-term follow-up and growth prediction are essential to guide timely corrective treatment to minimize the leg-length discrepancy in bone maturity. Full article

Carbon fiber textile-reinforced engineered cementitious composite (CTR-ECC) is widely utilized in structural strengthening applications due to its advantages of low weight and high strength. A comprehensive understanding of its mechanical behavior under off-axis tension is crucial for addressing the prevalent off-axis stress states in engineering practice. This paper presents an experimental investigation on the off-axis tensile properties of CTR-ECC. Specimens were fabricated with four off-axis angles: 0°, 15°, 30°, and 45°. The study revealed three main findings: (1) Under axial (0°) loading, failure is characterized by yarn fracture and interface slip, whereas off-axis tension induces a stable progressive delamination failure in textile-reinforced ECC systems. (2) While CTR-ECC exhibits higher tensile strength than plain ECC at all angles, its strength decreases significantly as the off-axis angle increases (e.g., a 27.1% reduction at 15°). Off-axis layouts, however, substantially improve energy absorption, with strain energy density increasing by up to 368.4% at 30°. (3) A phenomenological constitutive model was developed, which can adequately capture the stress–strain response of CTR-ECC under various off-axis angles, with coefficients of determination (R²) exceeding 0.9 in all cases. These results provide important insights into the failure mechanisms and performance design of CTR-ECC under off-axis tension conditions. Full article

Fatal free falls (FFF) represent a distinct form of blunt force trauma and pose a significant challenge in forensic investigations, particularly in estimating fall height and differentiating between accidental and suicidal events. Postmortem computed tomography (PMCT) enables detailed assessment of skeletal injuries, including quantitative evaluation of skull fracture patterns. Total Cranial Fracture Length (TCFL), derived from three-dimensional CT skull fracture scoring (3D-CT-SF), has been proposed as an objective indicator of impact severity; however, available evidence remains limited. This study aimed to assess the relationship between TCFL and fall height in fatal free falls and to evaluate the influence of selected anthropometric and biomechanical variables on cranial fracture severity. A retrospective analysis of 76 fatal free-fall cases examined between 2016 and 2024 was conducted using PMCT and autopsy data. TCFL was measured on three-dimensional volume-rendered CT reconstructions of calvarial fractures. Statistical analyses were performed for the entire cohort and separately for accidental and suicidal falls. No significant correlation between TCFL and fall height was observed in the overall cohort or among suicide cases. In contrast, a significant negative correlation between TCFL and fall height category was identified in accidental falls. TCFL showed significant positive correlations with body mass, body mass index (BMI), and kinetic energy, particularly in the suicide subgroup. TCFL is a promising objective parameter for assessing the severity of cranial injury in fatal free-fall cases. While its utility in estimating fall height appears limited in suicidal falls, TCFL may support forensic interpretation of fall dynamics and contribute to distinguishing the manner of death, especially in accidental cases. Further studies in larger, more diverse populations are warranted. Full article

Numerical simulation is an effective method for studying groundwater flow and heat transfer in geothermal energy projects. Describing the characteristics of thermal plumes is important for operational planning of geothermal energy projects. In contrast to shallow geothermal system, the injection temperature differs significantly from the natural temperature of thermal reservoir in high-temperature geothermal projects, which leads to changes in fluid density and dynamics viscosity. The purpose of this paper is to investigate the impacts of temperature-induced changes in density and dynamics viscosity on simulation. The Enhanced Geothermal System (EGS) in North Jiangsu Basin, China, is taken as a case project. Based on the theory of groundwater flow and heat transfer in porous-fracture dual medium, a numerical model of EGS is established to predict the thermal performance. The density and the dynamics viscosity in the model were set as either constant or temperature-dependent to simulate the hydraulic head and temperature of the production well. The influence of temperature-induced changes in density and dynamics viscosity on the simulation was quantitatively studied. The results show that temperature-induced change in dynamics viscosity has a greater impact on the simulation, with deviation in hydraulic head exceeding 20% if the dynamics viscosity is assumed constant. The temperature-dependent variation in viscosity should be incorporated into the simulation process to improve the accuracy of the calculation. In practice, EGS projects should maximize the temperature differential between produced and injected water. The increased viscosity of lower-temperature circulation water extends its residence time within the system, thereby facilitating more thorough heat extraction. This research enhances our understanding of the role of the temperature in groundwater flow and heat transfer within EGS. Full article

Dual beam laser welding of UNS S32750 superduplex stainless steel was performed to investigate the effect of beam-power distribution on microstructure and mechanical properties. Plates with a thickness of 3 mm were welded at a constant total power and travel speed using leading and lagging power splits of 50:50, 80:20, and 65:35. The heat affected zone width was metallographically estimated at approximately 100 µm for all conditions, consistent with comparable gross thermal exposure under constant nominal linear energy input (P_total/v). A slight modification to the power distribution altered the solidification texture and austenite morphology. The 50:50 configuration produced a refined ferritic matrix with a continuous network of grain boundaries, Widmanstätten, and intragranular acicular austenite. The 80:20 condition increased ferrite path continuity, while the 65:35 split produced an intermediate morphology. Vickers hardness reached a maximum for the 80:20 split (HAZ: 345 HV; weld metal: 349 HV). Ultimate tensile strength remained statistically constant between 908 MPa and 914 MPa, whereas elongation decreased from 28% at 50:50 to 24% at 80:20 and 23% at 65:35. All welds exhibited ductile fracture with microvoid coalescence, and electrochemical performance was comparable, with critical pitting temperature values between 78 °C and 91 °C. Beam power distribution primarily affects solidification morphology and enables control of the hardness-to-ductility balance, with a 50:50 split providing the most favorable combination of properties. Full article

Fiber-reinforced asphalt mixtures improve cracking resistance through fiber bridging, pull-out, and crack-path deflection, but their semi-circular bending (SCB) fracture energy is affected by coupled mixture, testing, and fiber-related variables. This study developed a source-aware and physically interpretable data-driven framework for predicting SCB fracture energy using a literature-derived database containing 261 valid sample-level records from nine source groups. The database was constructed through semantic extraction, unit normalization, rule-based checking, manual verification, and source identifier (SourceID) tracking. Optimum asphalt content, air voids, test temperature, loading rate, fiber dosage, fiber length, diameter, elastic modulus, and tensile strength were used as input variables. Under sample-wise testing, the selected model achieved a coefficient of determination (R²) of 0.89, a root mean square error (RMSE) of 0.0470 kJ/m², and a mean absolute error (MAE) of 0.0247 kJ/m² for the full dataset, while the fiber-containing subset achieved R² = 0.94, RMSE = 0.0194 kJ/m², and MAE = 0.0103 kJ/m². Source-aware validation showed higher prediction errors, indicating that cross-source generalization remains more challenging than internal sample-wise prediction. SHapley Additive exPlanations (SHAP) analysis identified temperature, fiber dosage, and fiber mechanical descriptors as dominant contributors, consistent with temperature-dependent viscoelasticity, fiber bridging, and pull-out mechanisms. The dosage–response analysis was restricted to the observed fiber-dosage range of 0–0.678%, providing a bounded screening tool rather than an extrapolative design equation. Full article

Ultra-high-performance concrete incorporating coarse aggregates (UHPC-CA) exhibits pronounced multi-scale heterogeneity and staged damage evolution. However, existing single-scale reinforcement strategies often fail to address the complete micro-to-macro fracture process, leaving a critical research gap in achieving full-stage crack control. To address this, this study introduces a novel cross-scale toughening strategy using hybrid steel fibers (SF) and calcium carbonate whiskers (CCW), and decouples the coupled influences of water-to-binder (W/B) ratio, coarse aggregate (CA), and multi-scale fibers via an orthogonal design. Mechanical properties, fiber dispersion, and pore structure are jointly characterized to establish structure–property relationships. An optimal composition (W/B = 0.32, CA = 18%, SF = 2%, CCW = 1%) is identified, achieving a balanced enhancement of strength and ductility. Results indicate that matrix densification is primarily controlled by W/B via pore refinement, while mechanical performance is governed by the interplay between fiber spatial uniformity and interfacial integrity; the roles of CA and CCW are clearly stress-state dependent. Furthermore, a novel cross-scale synergistic mechanism is revealed, in which micro-scale CCW regulates microcrack initiation and stabilizes the pre-peak response, whereas macro-scale SF dominates post-peak behavior through crack bridging and pull-out energy dissipation. This sequential activation enables a full-stage enhancement of tensile performance, shifting failure from brittle localization to pseudo-ductile multiple cracking. The findings provide a correlative framework for tailoring UHPC-CA through multi-scale hybrid reinforcement. Full article

This work investigates the Mode I fracture behavior of adhesive joints manufactured from unidirectional carbon fiber-reinforced epoxy composites (CFRP) under static and fatigue loading. Specimens were exposed to two degradation environments: hygrothermal conditions (60 °C, 70% RH) and saline conditions (35 ± 2 °C, 89% RH), for 1 and 12 weeks, and compared with non-exposed material. Double Cantilever Beam (DCB) tests were conducted to evaluate the influence of aging on fracture toughness. Thermal (Differential Scanning Calorimetry, DSC) and spectroscopic (Fourier Transform Infrared Spectroscopy, FTIR) analyses were performed to identify degradation mechanisms. DSC results showed no significant variation in glass transition temperature (T_g) under saline exposure, whereas hygrothermal aging increased T_g, indicating post-curing effects. FTIR analysis revealed moisture uptake and oxidation under saline conditions, while hygrothermal exposure mainly led to structural rearrangement. Critical energy release rate (G_IC) values were used to define fatigue test conditions, enabling the construction of fatigue initiation (ΔG–N) and crack propagation (G–da/dN) curves. A Weibull-based model was applied to describe fatigue initiation behavior. Results show that saline exposure promotes progressive degradation, whereas hygrothermal conditions may enhance performance due to post-curing effects. Full article