Cracking in high rockfill dam concrete face slabs, primarily arising from an insufficient understanding of surface heat dissipation under complex environmental conditions, remains a critical engineering challenge. This study systematically investigates surface heat dissipation behavior through a combination of 1:1 scale laboratory experiments and field in-situ monitoring. Specifically, the laboratory tests quantified the independent and coupled effects of wind speed, humidity, and evaporation on heat transfer coefficients. Furthermore, finite element back-analysis was employed to develop a multi-factor predictive model. Results reveal distinct dissipation mechanisms: under dry conditions, the coefficient follows a power-law relationship with wind speed with an exponent of 0.85, whereas under wet conditions, evaporative cooling dominates, regulated by a critical wind speed of 1.79 m/s. Consequently, a promote-then-retard dissipation strategy, implemented through phased flowing water curing and surface insulation, reduced maximum tensile stress by 18-22%. Ultimately, the developed model enables accurate temperature prediction in complex environments, overcoming limitations of constant-coefficient methods. These findings provide theoretical and practical foundations for enhancing construction quality and long-term durability of concrete face slabs.

This study presents a novel concrete stress measurement device, the Concrete Stress Meter (CSM), designed to directly monitor axial stress in concrete. Based on a unique structural design, the device transmits concrete axial stress to a dynamometer via an isolation cylinder. The CSM initiates monitoring immediately after concrete placement: it first uses a magnetic grid sensor to measure the stress development inside the isolation cylinder, and subsequently obtains the stress of the concrete outside the isolation cylinder under the action of uniaxial stress and triaxial stress via a composite mechanics algorithm. The stress measurement performance of the CSM under various loads with different elastic modulus was evaluated using the Temperature-Stress Testing Machine (TSTM), followed by validation of the algorithm's reliability and accuracy through finite element method (FEM) modeling with varying scales. Results show that in temperature effect tests, the maximum differences between CSM measured thermal stress and TSTM measured stress was 0.591 MPa, with difference rate of 9.80 %, respectively. Under external loads, the maximum differences between CSM measured stress and TSTM measured stress was 0.732 MPa, with difference rate of 9.15 %, respectively. FEM analysis demonstrates that when concrete elastic modulus ranges from 10 to 40 GPa and linear expansion coefficient from 6 x 10-6 to 10 x 10-6 (degrees C-1), the stress ratio between the cylinder interior and exterior ranges from 1.29 to 0.79. Under various working conditions, the concrete stresses calculated by the CSM's supporting algorithm are highly consistent with the simulated stress results. Under the action of both uniaxial stress and triaxial stress, the algorithm proposed in this paper can effectively calculate and obtain the stress of the concrete outside the cylinder. Statistical indicators were used to evaluate the prediction accuracy of the algorithm: the maximum Mean Absolute Error (MAE) is 0.175, and the coefficients of determination (R2) exceed 0.98.

The steel-concrete interface in steel-concrete composite structures is susceptible to interfacial void defects during both casting and service, posing a significant threat to structural load-bearing capacity. For early-stage micro-voids exceeding 2 mm in height, signal variations are weak and exhibit response characteristics similar to dense states, leading to feature ambiguity when using conventional criteria based on time-domain amplitude and attenuation or frequency-domain peak values and resulting in a high risk of missed detections. To address this limitation for early warning purposes, this study proposes a high-sensitivity identification method integrating an impact elastic wave response feature system with a feature-attention gated multi-layer perceptron (Feature-attention MLP). Based on full-scale model experiments from an engineering project, the temporal and spectral evolution patterns of impact elastic wave responses under varying dense conditions were analyzed. A comprehensive feature system, including time-domain statistical descriptors, spectral peaks, and sub-band energy distributions, was constructed, with Random Forest used for feature importance ranking and Top-K selection. An MLP classifier was then developed for automatic discrimination of dense states. A feature-level attention gating mechanism was introduced to enable adaptive weighting across feature dimensions, enhancing sensitive features while suppressing noise and structural variability. The final lightweight classifier contains 4052 trainable parameters, enabling rapid execution with an average CPU inference time of approximately 1.24 ms per sample. The average CPU inference time was approximately 1.24 ms per sample. Under the original train-validation split, the recall-prioritized operating point achieved a Void recall of 0.978 and a weighted F1-score of 0.780, accompanied by a non-negligible false-positive screening burden. Stratified five-fold internal validation yielded a balanced accuracy of 0.682 ± 0.021 and a Void recall of 0.845 ± 0.035 under the inner-validation-optimized threshold. These results demonstrate the preliminary potential of the proposed lightweight framework for engineering-oriented micro-void screening under the investigated full-scale conditions.

As a critical hydraulic structure, the safety of large prestressed aqueducts is essential. This study employs distributed optical fiber sensing based on PPP-BOTDA to monitor deformation in concrete beams during prestressed steel reinforcement corrosion and fracture, with results validated by finite element analysis (FEA). Using a real aqueduct as a case study, the influence of corrosion and fracture in three-way prestressed reinforcement under both emptying and normal water supply conditions is investigated via numerical simulation. A distributed optical fiber sensing system is preliminarily proposed for continuous monitoring of prestressed reinforcement performance. Results indicate that when the sensing fiber is within 150 mm of the corroded reinforcement, strain monitoring data show significant changes, and fracture locations are accurately identified. Under emptying conditions, corrosion of a single longitudinal prestressed steel bar in the bottom plate has minimal impact on concrete surface strain, whereas under water supply conditions, longitudinal reinforcement corrosion has a more pronounced effect than transverse or vertical reinforcement corrosion.

The preparation of magnesium (Mg) foils involves complex and labor-intensive rolling processes, along with a significant occurrence of defects such as fractures, which notably escalate production costs. In this study, high-purity magnesium, recognized for its excellent battery performance, was used as the initial sheet. By utilizing online heating rolling equipment and a low-temperature single-pass rolling process, 0.2 mm Mg foils were successfully prepared at different rolling temperatures (25 °C, 100 °C and 150 °C). This study extensively analyzed the deformation behavior of pure Mg foils at various rolling temperatures using techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and electron backscatter diffraction (EBSD). Furthermore, the fracture mechanism of the foils at 200 °C was investigated using high-temperature tensile testing equipment. The study revealed that as the rolling temperature increases from 25 °C to 150 °C, the texture strength of Mg foils gradually decreases. Notably, at a rolling temperature of 200° C, due to the sharp rise in the temperature of the foil near the roller and the influence of rolling tension, the Mg foil breaks.

Boolean operations play an important role in geometry processing and CAD/ CAM. To accelerate it, spatial searching trees such as Binary Space Partitioning (BSP) Trees and KD-trees are utilized. In this paper, an approach is presented to construct the BSP Trees for the Boolean operation, where each model is efficiently located in a separate subspace. Unlike conventional methods to calculate the splitting plane, our method utilizes a size-distribution blending weighted squared distance in the BSP Tree construction, where the intrinsic weight is determined based on the size and distribution of the three-dimensional (3D) model and largely reflects the model shape. After determining the intrinsic size-distribution blending weighted squared distance, the effective splitting plane is calculated using the Weighted Squared Distance Minimization (WSDM) method. By utilizing the size-distribution blending weighted squared distance, the generated BSP Tree can divide the two models efficiently, even when dealing with 3D models that exhibit substantial geometric variations. In our experiments, the BSP Tree generated by our method reaches higher Intersecting Triangle Report Accuracy (ITRA) and Non-intersecting Triangles Removal Rate (NTRR), which means more efficient hierarchies than other techniques on two mesh models. The results of intersection tests time consumption and the Boolean operations demonstrate the effectiveness and efficiency of the BSP Tree generated by our method.

Understanding the failure process in surrounding rocks is essential for assessing the stability of underground spaces and predicting potential disasters. Although failure patterns around openings of various shapes have been studied, the effects of geological discontinuities on the characteristics of failure zones around these openings remain inadequately understood. This study investigates failures around openings and flaws by analyzing acoustic emission (AE) characteristics. Digital image correlation (DIC) was employed to measure the failure zones of specimens during experiments, and particle flow code (PFC) software modeled the failure process. A statistical tool quantitatively assessed the cumulative number-strain curves of AE events, distinguishing between different distribution modes (single- or multi-peak). Additionally, the magnitude distribution and source mechanisms of AE events were analyzed to evaluate the effects of exposure conditions and flaw inclination angles on AE event occurrence. Both experimental and numerical results showed strong agreement, demonstrating that exposure conditions and flaw inclination angles significantly affect AE event distribution and magnitude. Exposed flaws tended to suppress AE events on the side containing the flaws, whereas unexposed flaws promoted AE events on the side with flaws, with this effect varying based on flaw inclination angles. These findings provide valuable insights into the fracture characteristics of surrounding rocks in deep underground spaces affected by geological discontinuities.

Purpose In this study, a high-precision inversion method based on field test data to determine the equivalent convection coefficient of a concrete surface was employed when employing the steel–polyurethane composite. Design/methodology/approach The research method of this article is as follows: (1) Design experiments to measure the temperature inside the concrete block when using steel polyurethane composite formwork; (2) Using temperature field reconstruction technology to invert the equivalent thermal convection coefficient of structural surfaces; (3) Prove that the surface temperature distribution of the structure is uniform; (4) Obtain a numerical simulation method for solving the equivalent thermal convection coefficient of concrete when using steel polyurethane composite formwork. Findings By analyzing the insulation field test results for the steel–polyurethane composite, two conclusions can be drawn: first, even if the steel groove is large and its wall thickness is very thin, concrete heat is dissipated primarily via the steel groove; and second, the unfilled area of the steel groove can be coated with a thin polyurethane layer, which can have a significant impact on the heat dissipation of the concrete, and the degree of this impact can be quantified. Based on the results, a finite element calculation method is proposed to calculate the equivalent convection coefficient of the concrete surface when employing a steel–polyurethane composite. Originality/value The proposed method can simulate and determine the equivalent convection coefficient of the concrete surface when steel grooves of any dimension are sprayed with polyurethane of any thickness.

A smooth particle hydrodynamic (SPH) method combined with the Herschel-Bulkley-Papanastasiou (HBP) model is proposed to simulate 3D concrete printing (3DCP). HBP model can better resolve the divergence of equivalent viscosity coefficient under small deformation and extend the compatibility of simulation to dilatant and pseudoplastic fluids, so it possesses natural superiority in modelling the 3D printing of cement-based material with visco-plastic rheology behaviour. The HBP-based SPH method considers the influence of the printing parameters including nozzle characteristics and printing-to-extrusion velocity ratio on the cross-sectional geometry of the deposited filament, and its outcomes agree qualitatively well with the experiment results. Furthermore, by utilising process parameters furnished by simulation cases, it is possible to determine the critical conditions under which filaments printed by different nozzle shapes are vulnerable to tearing, and the corresponding critical intervals when tearing occurs are also defined. 3DPC experiments verify these findings and confirm that SPH simulation provides additional information on the geometric characteristics of single-layer structures, as well as physical quantities that cannot be straightforwardly measured.

The emergence of underwater 3D concrete printing (U3DCP) technology has brought forth novel methods for the construction and repair of submerged structures. The conventional practice in U3DCP adding anti-washout admixtures (AWAs) will lead to cross-effects among various working properties of the printing materials and contradictory issues between performance, which may also be one of the obstacles that hinder the progress of U3DCP in-site applications. Hence, this paper presents a novel strategy for printing concrete in an environment containing underwater seepage inhibitor (USI) without adding AWAs into concrete. The findings indicate that the novel U3DCP possesses lower yield stress and plastic viscosity along with greater thixotropy than the traditional U3DCP. Moreover, it can significantly reduce or even eliminate the risk of surface cracking when printing fresh U3DPC. And the concrete printed in low-dose USI has better interface bonding and compressive strength, interpreted from a microscopic perspective via FIRT and SEM analysis. Furthermore, the rheological properties and interlayer bonding of the novel U3DCP are analyzed using grey relational analysis (GRA), and it is discovered that the flowability of U3DPC is highly correlated with its interface bond strength.

This work examined the shear behavior of concrete deep beams reinforced with basalt fibers (BF) and basalt fiber reinforced polymer (BFRP) bars without shear reinforcement. Eleven deep beams with and without BF were cast and tested under 4-point loading. The shear span-to-depth ratio, the ratio of BFRP bars, the strength of concrete, and the effect of volume fraction (0, 0.10 %, and 0.15 %) and aspect ratio (800 and 2000) of BF on the shear capacity beams are investigated. The results reveal that there is an insignificant improvement in shear capacity by increasing the ratio of BFRP bars and the strength of concrete. The shear capacity of beams improved with the increase of the reinforcing index (RI, i.e. the production of volume fraction and aspect ratio) of BF, the shear capacity and maximum deflection increased by 61.3 % and 26.3 %, respectively, when the RI of BF increased from 0 to 3.0. Besides, the effect of the aspect ratio is more significant than the volume fraction of BF. However, the failure modes were not significantly influenced by the features above, all beams were subjected to the crush of the compressive region. Additionally, considering the numerous features and complex mechanisms of shear transfer, the LightGBM model is based on the data about 389 specimens for other reports established for predicting the shear capacity of the test specimens, and the SHAP method is combined for the interpretation of involved features.

In phase change material-based battery thermal management systems (PCM-BTMS), heat buildup around the battery is more pronounced at high discharge rates due to the lower thermal conductivity of the PCM. To address this challenge, a transverse fin-casing composite structure (TFCCS) is added in PCM-BTMS, and its thermal performance is evaluated in comparison with BTMS without fins (PCM-BTMS) and BTMS with conventional transverse fins (TF-PCM-BTMS). Numerical simulations reveal that TFCCS enhances both longitudinal and transverse heat conduction by constructing a “T-shaped” heat conduction network, which makes the temperature distribution and PCM melting in the system more uniform. Compared with the PCM-BTMS and TF-PCM-BTMS, TFCCS-PCM-BTMS reduces the maximum battery temperature (Tmax) by 24.4

The enhanced heat transfer at the metal/semiconductor interface is paramount for heat dissipation in electronic devices. In this study, the non-equilibrium molecular dynamics (NEMD) method is employed to elucidate the mechanism of the effect of two-dimensional sinusoidal surface roughness structure on Cu/diamond thermal boundary conductance (TBC). The results indicate that the Cu/diamond TBC increases with the fluctuation height and frequency increase. However, the efficiency of the effect of fluctuation frequency on the TBC varies for different fluctuation heights. The rough interface significantly improves the phonon vibrational coupling between Cu and diamond by phonon density of state (PDOS) analysis. When the interfacial fluctuation height is larger than the phonon wavelength, the increase of phonon reflection point sites further enhances the thermal transport capacity of the Cu/diamond interface, resulting in a significant increase in the growth rate of TBC. The concept of phonon participation ratio is introduced to quantify the effect of interface roughness on phonon localization. Simulations show that phonon localization is almost independent of the interface roughness. This work establishes a foundation for the development of interfacial thermal management techniques.

Under long-term alternating effect of freeze-thaw and low-velocity flowing water, characterising the leaching-abrasion behaviour of canal lining concrete has become a technical bottleneck in evaluating its durability in cold regions. To investigate this behaviour and elucidate the mechanisms and effects of these processes, this study conducted experiments under alternating freeze-thaw and flowing water conditions, with a maximum flow velocity of 5m/s. The evolution of macro-and micro-scale properties, as well as phase composition, was analysed, and boundary movement criteria were established for concrete surface. The experimental results show that the abrasion depth of concrete increases linearly with service time. Compared to warm regions and static water environments, the combined effect of freeze-thaw cycles and flowing water in cold regions accelerates the leaching-abrasion rate by approximately 8 times. The rate is further amplified by factors of 1.18, 1.37, 1.22, 1.29, and 1.37 at flow velocities of 1, 2, 3, 4, and 5 m/s, respectively. This enhancement is primarily attributed to the deterioration of interfacial transition zone. Freeze-thaw are the dominant factor, inducing numerous micro-cracks, while flowing water significantly accelerates calcium leaching. Boundary movement on the concrete surface occurs when the residual solid calcium content and aggregate protrusion height reach critical values. The critical calcium content is 25 %, while the protrusion height decreases linearly with increasing aggregate diameter, reaching 60 % and 30 % for diameters of 4.75 and 9.5 mm, respectively. Under the action of leaching-abrasion alone, flowing water at velocities up to 5 m/s significantly accelerates leaching but causes negligible abrasion.

Distributed acoustic sensing shows great potential for pipeline monitoring. However, internally deployed and unfixed sensing cables are highly susceptible to disturbances from water flow noise, severely challenging impact source localization. This study proposes a novel two-step method to address this. The first step employs Variational Mode Decomposition (VMD) combined with Short-Time Energy Entropy (STEE) for the adaptive extraction of impact signal from noisy data. STEE is introduced as a stable metric to quantify signal impulsiveness and guides the selection of the relevant intrinsic mode function. The second step utilizes the Pruned Exact Linear Time (PELT) algorithm for accurate signal segmentation, followed by an unsupervised learning method combining Dynamic Time Warping (DTW) and clustering to identify the impact segment and precisely pick the arrival time based on shape similarity, overcoming the limitations of traditional pickers under conditions of complex noise. Field tests on an operational water pipeline validated the method, demonstrating the consistent localization of manual impacts with standard deviations typically between 1.4 m and 2.0 m, proving its efficacy under realistic noisy conditions. This approach offers a reliable framework for pipeline safety assessments under operational conditions.

With the advancement of carbon capture and storage (CCS), enhanced geothermal systems (EGS), and other deep rock engineering projects, understanding the mechanical behavior of fractured rock is crucial for predicting potential disasters in underground space utilization. Triggered seismicity and induced fault slip are closely linked to unloading-induced fracture slip-a process that remains poorly understood. In this study, the characteristics of frictional slip were investigated in laboratory experiments using Acoustic Emission (AE) monitoring, including the frequency spectra and magnitude of AE events. The Digital Image Correlation (DIC) method was employed to analyze the slip process by measuring shear strain near the rock fracture. Additionally, Particle Flow Code (PFC) simulations were used to model AE events and examine the mesoscale failure mechanisms of frictional slip. The results indicated that failure patterns depend on the unloading rate of normal stress in both direct shear and unloading shear tests. Frequency spectrum analysis identified 300 kHz as the dominant frequency component in unloading shear tests. Both experimental and numerical results demonstrated that the temporal distribution of AE events correlates with unloading rates. This study provides critical insights into the fracture and failure mechanisms of frictional slip, offering valuable implications for the safety and design of underground rock engineering projects.

Soil-rock mixture landslides frequently occur in steep mountainous regions, indicating enormous destructive potential. Consequently, these landslides have attracted much attention from researchers in recent years. This paper presents a simple and effective meshless numerical method based on Smoothed Particle Hydrodynamics (SPH) to simulate the movement and impact forces of heterogeneous soil-rock mixture landslides. In this method, soil and rock are discretized as SPH particles with different material properties and are modeled as elastoplastic and elastic materials, respectively. The ideal elastoplastic model with a nonassociated flow rule, combined with the Drucker-Prager (DP) yield criterion, is employed to describe the constitutive response. First, the paper validates the soil pressure exerted on the bottom wall of a stationary container. Second, the impact experiment of a single rock sample is verified, and the effects of the rock density, shape, and drop height are further analyzed. Last, the proposed method is employed to simulate and validate the movement and impact force of homogeneous soil landslides, followed by heterogeneous landslides. The results indicate that the proposed method is feasible for simulating the movement and impact forces of heterogeneous soil-rock mixture landslides. Additionally, this method is simple to implement, highly flexible, and capable of accommodating arbitrarily-shaped rocks. The presence of rocks alters the characteristics of the impact force and partly increases the peak impact force, particularly in steep slope scenarios. These findings enhance our understanding of the complex phenomena associated with heterogeneous landslides, including debris flows that involve multiple phases and scales, and offer significant guidance for disaster prevention and mitigation in geological engineering.

Hydrogel materials have broad application prospects in biomedical and other fields. Understanding the large deformation and failure characteristics of hydrogel materials is crucial for their engineering applications. However, simulating the compressive large deformation and failure behavior of hydrogel-like soft materials in three-dimensional scenarios is very challenging. This paper proposed a stabilized three-dimensional non-ordinary state-based peridynamics approach for simulating the compressive large deformation and failure behavior of hydrogel-like soft materials. To control numerical instabilities, a supplementary force state of zero-energy modes is introduced, and a second-order Reduced Polynomial hyperelastic model is applied for constitutive modeling. The computational framework employs an explicit dynamic solution method to simulate three-dimensional large deformation and failure of hyperelastic specimens with complex geometric configurations. Due to its nonlocal theory and mesh-free properties, the proposed method can effectively address the challenges of simulating large deformation and fracture failure of soft materials. First, different zero-energy control methods are validated, followed by an analysis of models with different grid spacings to verify the model's mesh convergence. Finally, compression failure tests of hydrogel spheres under different loading rates are simulated to verify the reliability and simulation performance of the proposed method. In compression failure scenarios, the predicted deformation and load-displacement responses are highly consistent with experimental observations, demonstrating the effectiveness and accuracy of the developed stabilized three-dimensional state-based peridynamics framework in predicting the failure behavior of soft materials under compressive large deformations.

With the size down and integration of power devices, the internal thermal management problem has become particularly severe. Especially in the channel region, significant heat generation can lead to a rapid increase in device temperature, which not only exacerbates the degradation of electrical performance in the channel region but also poses a severe threat to the overall reliability and stability. The drift-diffusion (D-D) transport method is employed to calculate the dynamic heat generation of n-MOSFET power devices, and the effects of size and electrical parameters on the thermal production mechanism are analyzed. Considering the quasi-ballistic effect of carrier transport in nanoscale devices, the ballistic diffusion equation (BDE) is introduced to calculate the heat transfer characteristics, and the temperature distribution is explored. The results show that, under a given input voltage, the heat accumulation due to short-channel effects becomes more pronounced with the Kn increase, forming high-temperature hotspots between the gate and drain. When the scale shrinks further (Kn = 5 and Kn = 10), energy accumulation will occur between the gate and source, increasing temperature rise. At smaller scales, the thermal production on each side of the gate increases with the rise of the conduction voltage, especially under the working condition of Kn = 10, Vg = Vd = 1.0 V. Moreover, heat production and temperature transfer have a significant time delay. Specifically, it takes 15 fs for heat generation to reach a stable state, while the stable transfer of heat takes 12 ps.