Search Results (3,226)

With advantages in efficiency and sustainability, assembly splicing technology promotes construction industry upgrading. However, research on the seismic response of assembly splicing subway stations (ASS) is particularly scarce. This work studies the asymmetric ASS in soft soil, establishing a refined finite element model with soil–structure interactions. Three seismic records with different frequency characteristics are applied for nonlinear incremental dynamic analysis. Based on the seismic records that produce the most unfavorable seismic response, this research is conducted on the damage distribution characteristics and the mechanical responses. In addition, the influence of the splicing response at different locations on the interlayer displacement and internal forces of structures is systematically studied. The results indicate that when seismic records with low-frequency characteristics are inputted, the ASS structure in soft soil develops into the most unfavorable state. Under strong seismic action, the top joint of the sidewall exhibits significant horizontal sliding and opening, making key areas of weak seismic performance. It also indicates that the interface contact between precast and cast-in-place components is the primary factor that is causing internal force redistribution. This study provides a reference for performance-based seismic design of ASS in soft soil. Full article

Irregular multistorey buildings are prone to seismic forces due to torsional effects resulting from the eccentricity between the mass and stiffness centres. Shear walls are essential in multistorey buildings for improving structural behaviour when subjected to earthquake loads. The seismic response of buildings is highly sensitive to the placement and configuration of shear walls within the building infrastructure. This research focuses on optimising the location of shear walls in a T-shaped irregular reinforced concrete structure for better seismic resilience. The structural analysis is carried out, and the building is evaluated via the response spectrum as per the provisions of IS 1893:2016. This study examines various shear wall configurations to achieve optimised modal mass participation, thereby reducing dynamic irregularities and enhancing overall seismic performance. The impact of these optimised locations is assessed across various seismic zones in India, with a focus on critical response parameters, including lateral displacement, interstorey drift, storey shear, and base shear. The results reveal that strategically optimised shear wall placement significantly enhances seismic performance by reducing lateral drift and torsional effects. In this study, the shear wall configurations that resulted in higher modal participation factors and lower eccentricities between the centre of mass and the centre of stiffness demonstrated a superior seismic performance across all considered seismic zones. Full article

Most machine learning algorithms operate on vectorized data with Euclidean structures because of the significant mathematical advantages offered by Hilbert space, but improved representational efficiency may offset more involved learning on non-Euclidean structures. Recently, a method that integrates the marginalized graph kernel into the Gaussian process regression framework was used to learn directly on molecular graphs. Here, we describe an implementation of this method for crystalline materials based on effective crystal graph representations: the molecular graphs of 128-atom supercells of body-centered cubic (BCC) iron with periodic boundary conditions. Regressors trained on hundreds of time steps of a density functional theory molecular dynamics (DFT-MD) simulation achieved root mean square errors of less than 5 meV/atom. The mechanical stability of BCC iron was investigated at high pressure and elevated temperature using regressors trained on short DFT-MD runs, including at conditions found in the inner core of the earth. Phonon dispersions obtained from the short runs show that BCC iron is mechanically stable at 360 GPa when the temperature is above 2500 K. Atoms in the super cell were displaced in the direction of the first, second, and third nearest-neighbors from selected configurations that included thermal atomic displacements, and forces exerted on the displaced atoms were computed by numerical differentiation of the regressors. Full article

This work explores NH₃/air non-premixed combustion in a mixing layer, with the objective of quantifying the influence of key parameters on ignition and flame dynamics. A series of two-dimensional simulations were conducted with forced ignition. The evolutions of the Damköhler number (Da) and flame stretch at the peak heat release rate for cases with successful/unsuccessful ignition were examined. It was found that for the cases with successful ignition, the Damköhler number is always larger than unity, the flame stretch maintains a positive value, and the tangential diffusion consistently dominates the normal diffusion all the time. On the contrary, for the cases with unsuccessful ignition, the Damköhler number gradually becomes less than unity, and the value of the flame stretch changes from positive to negative as time advances. During flame quenching, the value of the normal diffusion term becomes larger than that of the tangential diffusion term. The effects of mixing layer thickness on the ignition kernel evolution were assessed. It was shown that a thicker mixing layer promotes ignition kernel development. The ignition process is also influenced by the location of the spark in the mixture fraction space. Finally, the flame dynamics were analyzed in terms of scalar dissipation rate ($\chi$), displacement speed $S_d$, and flame stretch ($\kappa$) for various cases. The results showed that the $S_d$ is negatively correlated with the $\kappa$ and $\chi$. The Markstein length was evaluated, and it does not differ between the cases with varying mixing layer thickness. Full article

The oil layers in the Dongying Formation offshore oilfield are severely contaminated. The near-wellbore reservoir pore throats are blocked, which seriously affects the development effect. It has become urgent to implement acidizing stimulation measures. However, the target reservoir is deeply buried, has high reservoir pressure, and is highly sensitive. These factors result in high pressure during acidizing operations, a long single-trip time for raising and lowering the tubing string, and high costs. Moreover, acid that is not promptly returned to the surface after acidizing can cause secondary pollution to the reservoir. This work proposes an integrated tubing string to perform reverse displacement and reverse squeeze. With this, acid can be injected into the formation through the annulus between the casing and tubing. The residual acid and its post-acidizing derivative residues are rapidly lifted to the surface by the reciprocating suction action of the return pump. Based on this, the structure and specifications of the acidizing-flowback tubing string are designed through the flow rate analysis method. The tubing string is mainly affected by mechanical effects, including buoyancy, piston effect, flow viscosity effect, helical bending effect, temperature difference effect, and expansion effect. The maximum deformations are 1.4 m, 1.9 m, 0.18 m, 2.7 m, 1.8 m, and 2.5 m, respectively. The total deformation is less than 3 m. Simulation results from three groups of oil wells at different depths indicate that the axial force of the tubing string ranges from 400 to 600 kN. The stress ranges from 260 to 350 MPa, deformation is 1.1–2.4 mm, and the safety factor exceeds 3.0. This can effectively ensure the safety of on-site operations. Based on the actual field conditions, the acidizing-flowback tubing string is evaluated. This verifies the effectiveness of the acidizing-flowback tubing string. This research provides an economical and efficient operation process for acidizing operations in the Dongying Formation offshore oilfield. It achieves the goal of removing reservoir contamination and provides guidance for the unblocking and stimulation of low-permeability and sensitive reservoirs in the middle and deep layers of offshore oilfields. Full article

This study presents a novel structural framing solution designed to improve seismic energy dissipation and limit displacements, aiming to serve as an effective alternative to traditional precast systems employing pendulum-based isolation. While pendulum mechanisms mitigate seismic forces by decoupling the superstructure from ground motion, they are typically characterized by high implementation costs, mechanical complexity, and post-event maintenance challenges. In contrast, the proposed approach integrates seismic performance enhancements within the structural frame itself, removing the dependency on external isolation components. The system leverages a combination of pinned and semi-rigid beam-to-column joints that are tailored for use within dry precast construction technologies. These connection types not only support rapid and labor-efficient assembly but also, when properly detailed, offer robust hysteretic behavior and deformation control under dynamic loading. The research includes both experimental testing and numerical simulations focused on the cyclic response of these connections, enabling a comprehensive understanding of their role in dissipating energy and delaying damage progression. Recognizing the industry’s frequent emphasis on construction speed and upfront cost-efficiency, often at the cost of long-term reparability, this work introduces an alternative framework that emphasizes resilience without compromising construction practicality. The resulting system demonstrates improved post-earthquake functionality and reduced downtime, making it a promising and economically viable option for seismic applications in precast construction. This advancement supports current trends toward performance-based design and enhances the structural reliability of dry-assembled systems in seismic regions. Full article

Background: The radiocapitellar articulation of the elbow joint is particularly susceptible to subluxation and dislocation. Joint stability can be quantified using the stability ratio, a biomechanical parameter of joint stability defined as the ratio of the maximum dislocating force the joint can resist in relation to the joint compressive force. The purpose of this study was to biomechanically assess the stability of the radiocapitellar joint in the anterior and posterior direction across varying degrees of elbow flexion. Methods: Eight fresh-frozen cadaveric elbows, average age 68.9 years (range 61–73 years; 3 males and 5 females; 7 left and 1 right) were tested. The distal humerus and proximal radius were dissected of all soft tissues to isolate the radiocapitellar articulation. The radius and humerus were mounted on a custom jig that allows for positional adjustment and incorporates a material testing machine. Each specimen was mounted at neutral forearm position and tested at 30, 45, and 60 degrees of anatomical elbow flexion. All specimens were subjected to 10 mm of anterior–posterior displacement for 5 cycles at 20 mm per minute with 40 N of compressive load. Subluxation force, displacement at subluxation force, linear stiffness, stability ratio, and energy absorbed were calculated. Results: In all degrees of elbow flexion, the stability ratio in the posterior direction was significantly higher than the anterior direction by an average of 39.8 ± 32.6% (p < 0.025). Maximum subluxation force was also significantly higher in the posterior direction when compared to the anterior direction (p < 0.027). There was no significant difference in any other parameters. Conclusions: The stability ratio and maximum subluxation force of the radiocapitellar joint when positioned in neutral forearm rotation are significantly greater in the posterior direction when compared to the anterior direction. This finding provides quantitative insights and a biomechanical rationale for the propensity of anterior instability in the radiocapitellar joint. Full article

To address the challenge of simulating shear failure in anchor bolts within FLAC3D, a shear failure criterion, F_s(i) ≥ F_smax(i), is proposed based on the PILE structural element. Through secondary development using the FISH programming language, a modified mechanical model of the PILE element is established and integrated into the FLAC3D-FISH framework. Comparative analyses are conducted on shear tests of bolt shafts and on anchor bolt support performance under coal–rock interface slip conditions, using both the original PILE model and the modified mechanical model. The results demonstrate that the shear load–displacement curve of the modified PILE model clearly reflects shear failure characteristics, satisfying a quantitative shear failure criterion. Upon failure, both the shear force and axial force of the structural element at the failure point drop abruptly to zero, enabling effective simulation of shear failure in anchor bolts within the FLAC3D environment. Using the modified model, the distribution of principal stress differences in the surrounding rock after roadway excavation is analyzed. Based on this, the concept of a stress-bearing ring in the surrounding rock is introduced. The reinforcing effects of bolt length, spacing, and ultimate load capacity on the stress-bearing ring in weak and fractured surrounding rock are investigated. The findings reveal that: (1) shear failure initiates in bolt shafts near the coal–rock interfaces, occurring earlier near the coal–floor interface than near the coal–roof interface; (2) the stress-bearing ring in weak and fractured surrounding rock shows a discontinuous and uneven distribution. However, with support improvements—such as increasing bolt length, reducing spacing, and enhancing failure load—the surrounding rock gradually forms a continuous stress-bearing ring with more uniform thickness and stress distribution, migrating inward toward the roadway surface. Full article

Extensive high and steep open-pit slopes in gneiss are distributed in cold regions at high altitudes or high latitudes of China, such as Qinghai, Tibet, and Xinjiang, posing significant hazards to mine safety. Several recent slope failure incidents highlight the urgent need to study the failure modes and mechanisms of gneiss open-pit slopes in these cold regions. This study focuses on the 14 September 2023 landslide at the Jinbao Mine in Xinjiang. Initially, field investigation and displacement monitoring were employed to analyze its failure characteristics and mode. Subsequently, utilizing mechanical parameters of the gneissic foliation and the rock mass obtained under various conditions, discrete element numerical modeling was conducted to study the failure mechanisms. The results indicate that the landslide was a typical bedding failure characterized by an upper bedding-controlled sliding zone, combined with buckling and crushing of the slope toe. Under the long-term combined effects of rainfall, freeze–thaw cycles and blasting, the shear strength of the gneissic foliation decreased. This reduction led to a decrease in the anti-sliding force and an increase in the sliding force within the upper bedding-controlled sliding zone. Consequently, the load transferred to the rock mass at the slope toe progressively increased. Under prolonged compression, the toe rock mass experienced bending, which intensified over time. Coupled with the strength reduction caused by the repeated action of rainfall, freeze–thaw cycles and blasting, the toe rock mass gradually fractured and ultimately failed in a buckling mode. This led to the loss of support for the upper mass, which then subsided along the foliation, precipitating the landslide’s overall instability. Full article

This study aims to reveal the influence mechanisms of particles to provide a basis for screening high-efficiency foam stabilizers of nanoparticle (NP) and surfactant (SF). Molecular simulation was used, including Stretching Molecular Dynamics (SMD) for liquid film rupture, Mean Squared Displacement (MSD)/Radial Distribution Function (RDF) for water molecule behavior, NP interface tendency analysis, and interface traction force analysis. The system used silica (SiO₂) NPs (silane-modified to adjust hydrophilicity–hydrophobicity), three SFs [DTAB, CHSB, BS12; single/mixed systems], water (liquid phase), and nitrogen (gas phase). NPs need balanced hydrophilicity (to adsorb water) and hydrophobicity (to stay at the gas–liquid interface); 10% silane-modified NPs performed best, with 44% higher critical traction force for film rupture than unmodified NPs, effective water adsorption (molecules within 0.3–0.4 nm), and 12% interface presence probability. SFs (especially mixed systems like DTAB + BS12) attracted NPs to form stable composites, binding more tightly than single SFs and reducing SF mobility. The NP-SF system showed superior stability: DTAB + BS12 + NPs had the highest critical traction force (816.11 kJ·mol⁻¹·nm⁻¹) and longest rupture time (1.61 ns); the traction work required to pull NPs in the composite (2443.87 kJ·mol⁻¹) was much higher than that required for pure NPs (991.63 kJ·mol⁻¹). Finally, an experiment was conducted to measure the initial foam volume and drainage half-life of different systems to verify the simulation results. Full article

In offshore jack-up operations, it is common to reinstall spudcans close to existing footprints, which could result in asymmetric soil distribution and potential instability risks. This study investigates the mechanical behavior and stability of spudcans during reinstallation, focusing on the influence of footprint geometry, spudcan type, and offset distance. The coupled Eulerian–Lagrangian (CEL) method in ABAQUS is utilized together with soil strength reduction to assess stability. Both single-factor and orthogonal experimental designs are employed to systematically evaluate parameter effects. Results show that the footprint diameter has a greater impact than the depth, increasing the peak horizontal force by 33.4% and the moment by 10.9% due to enhanced soil asymmetry. Rectangular spudcans with tapered bases generate twice the vertical resistance and exhibit 8.8% smaller lateral displacements compared to circular spudcans. Offset distance significantly affects reinstallation performance, with adverse conditions occurring at 0.5 times the diameter of the spudcan. Orthogonal analysis further confirms that the offset distance has the greatest influence among the factors studied. These findings emphasize the necessity of considering footprint geometry, spudcan design and positioning to ensure safe and stable reinstallation, and provide guidance for engineering design and risk assessment of repeated spudcan operations. Full article

This study investigates the influence of shallow water-bearing sand layers on surface subsidence characteristics in coal mining areas with thick loose strata, with the ultimate goal of contributing to sustainable environmental protection. Firstly, a numerical simulation test was designed to analyze and study the influence of the loose layer thickness, mining height, bedrock slope, and sand inclusion on the surface movement and deformation characteristics. Secondly, the mechanical model of seepage flow in the sand layer was established to study the influence mechanism of the internal stress distribution of the sand layer and the seepage of the water body after mining on the surface subsidence. Finally, by studying the law of surface subsidence corresponding to the mining of 3205 working face in a mine, it was found that mining caused the partial overlying soil layer to move integrally and generate a large displacement difference with the adjacent layer, which verifies the conclusions of numerical simulation and mechanical analysis. The results of the study show that the thickness of the loose layer is the main control factor that causes the surface subsidence range and the building damage to increase; the shallow water-bearing sand-bearing layer has two types of movements: displacement and flow. The critical hydraulic slope has not reached the sand. The layer has a linearly increasing horizontal displacement value in the thickness direction; when the critical hydraulic slope is reached, the sand layer cannot transmit the frictional force, causing the overlying soil layer to slide as a whole. Both forms are prone to tensile damage on the surface. The research results provide a theoretical basis and practical case for surface subsidence reduction and green mining under similar geological conditions. Full article

(1) Background: This study proposes investigating the biomechanical stability of a novel 6-hole L-shaped plate for symphyseal fixation, which allows for reduction and stability in two planes. The results of the novel plate are compared to the standard plate; (2) Methods: The novel plate fixation and the standard 6-hole pubic symphyseal plate were tested with a pelvis model simulating an APC III injury. Each group of 10 pelves was subjected to a cyclic biomechanical single-leg-stance test for 30,000 cycles simulating partial bearing loading at 1 Hz, followed by a maximum load-to-failure test. The stiffness and displacement were evaluated and analyzed; (3) Results: Stiffness measurements during cyclic loading revealed no significant differences between the groups (p = 0.514). The cumulative plastic deformation was significantly lower in the novel plate group (p = 0.005). Load-to-failure testing demonstrated that both constructs exhibited similar ultimate strength, with no significant difference in the mean of maximum force between the novel (400.61 ± 44.65 N) and reference (433.02 ± 87.60 N) groups (p = 0.804); (4) Conclusions: The novel plate provides comparable biomechanical stability to the reference plate under the tested cyclic loading conditions, suggesting that it could be a viable alternative to the existing standard. However, further research is necessary to understand the clinical outcomes and long-term impacts. Full article

In automated sorting and grasping of livestock meat cuts, the ideal assumption of symmetric mass distribution is often violated due to irregular morphology and soft tissue deformation. Under the combined effects of gripping forces and gravity, the originally balanced configuration evolves into an asymmetric state, resulting in dynamic shifts of the center of gravity (CoG) that undermine the stability and accuracy of robotic grasping. To address this challenge, this study proposes a CoG trajectory prediction method tailored for meat-cut grasping tasks. First, a dynamic model is established to characterize CoG displacement during grasping, quantitatively linking gripping force to CoG shift. Then, the prediction task is reformulated as a nonlinear state estimation problem, and a Small-Target Bayesian–Probability Hypothesis Density (STB-PHD) algorithm is developed. By incorporating historical error feedback and adaptive covariance adjustment, the proposed method compensates for asymmetric perturbations in real time. Extensive experiments validated the effectiveness of the proposed method: the Optimal Sub-Pattern Allocation (OSPA) metric reached 4.82%, reducing the error by 4.35 percentage points compared to the best baseline MGSTM (9.17%). The task completion time (TC Time) was 6.15 s, demonstrating superior performance in grasping duration. Furthermore, the Average Track Center Distance (ATCD) reached 8.33%, outperforming the TPMBM algorithm (8.86%). These results demonstrate that the proposed method can accurately capture CoG trajectories under deformation, providing reliable control references for robotic grasping systems. The findings confirm that this approach enhances both stability and precision in automated grasping of deformable objects, offering valuable technological support for advancing intelligence in meat processing industries. Full article

As Canada experiences a growing number of newcomer students with refugee backgrounds, K-12 educators face challenges to meet students’ unique academic, linguistic, and psychosocial needs. This paper examines the role of educational technology (EdTech) to bridge the resource and training gap by enhancing teacher preparedness through an accessible, inclusive, and trauma-informed digital resource. This study presents a qualitative case study methodology to analyze the interactive online manual, Supporting Teachers to Address the Mental Health of Students from War Zones. The research utilizes three data sources: feedback from 110 educators through a questionnaire, observational data from 69 students from two separate pre-service teacher cohorts, and an expert evaluation report conducted by university curriculum specialists. Findings suggest that successful EdTech for refugee-background student initiatives must be trauma-informed, strength-based, culturally responsive, and designed with usability and accessibility in mind. Furthermore, collaboration between K-12 educators, researchers, and developers is vital to ensure that there is alignment of pedagogy and technology. Full article