Search Results (4,086)

To reveal the evolution laws of shear mechanical behavior and size effect of prestressed Recycled Aggregate Concrete (RAC) beams under dynamic loading conditions, a three-dimensional five-phase meso-scale numerical model was established based on the ABAQUS2020 software. The bond–slip behavior between steel bars and concrete was considered, and prestress was applied using the temperature cooling method. The effects of prestress level, cross-sectional size and strain rate on failure modes, load–displacement curves, ultimate shear capacity and nominal shear strength were systematically investigated. The results show that increasing the prestress level can significantly restrain the initiation and propagation of diagonal cracks, reduce the brittleness of the failure mode, and effectively mitigate the shear size effect. The nominal shear strength decreases obviously with an increase in cross-sectional size but increases significantly with an increase in strain rate, exhibiting a pronounced strain rate hardening characteristic. Large-scale beams are more sensitive to strain rate, and a high strain rate can reduce the disparity in shear performance among members of different sizes and further weaken the size effect. Based on Bažant’s Size Effect Law (SEL), a modified formula for dynamic shear strength considering the coupled effects of prestress level, strain rate and cross-sectional size was proposed by introducing a prestress enhancement coefficient γ and a strain rate enhancement coefficient β. The calculated results of this formula are in good agreement with the numerical results obtained in this study. Within the investigated parameter range, the present work can provide a reference for the shear design and safety assessment of prestressed recycled aggregate concrete beams under dynamic loading. Full article

Does mandatory sustainability disclosure improve the quality of corporate financial reporting immediately, gradually, or with delay? We address this question using Saudi Arabia’s January 2021 Tadawul ESG Disclosure Guidelines—the first comprehensive sustainability disclosure framework in the Gulf Cooperation Council and a uniform, accurately dated regulatory shock affecting all listed firms. Using a balanced panel of 135 non-financial firms over 2017–2024 (1080 firm-year observations), we estimate absolute discretionary accruals from the Modified Jones Model and employ event-time fixed-effects regressions with Driscoll–Kraay standard errors robust to heteroskedasticity, autocorrelation, and cross-sectional dependence. We document a temporal paradox: reporting quality did not change in the announcement year (2021), deteriorated significantly in 2022 (+28%) and 2023 (+38%) relative to the pre-reform baseline, and then improved significantly in 2024 (−17%). The pattern survives performance-matched discretionary accruals, exclusion of the 2020 COVID-19 year, a placebo test, sectoral disaggregation across nine Tadawul-aligned industry groups, and a battery of pre-reform firm characteristics. Heterogeneity analysis identifies the underlying mechanism: voluntary pre-2021 ESG disclosers and firms with stronger pre-reform governance exhibit amplified short-run deterioration, while larger firms with pre-existing reporting infrastructure show a substantially attenuated paradox. These patterns are jointly consistent with the adjustment-cost mechanism we develop: the reform redirected scarce reporting governance toward the new disclosure margin during a three-year compliance buildout, after which the constraining effect on accrual-based earnings management emerged. The findings carry direct implications for the design and evaluation of mandatory sustainability disclosure reforms currently advancing across emerging and developed markets. Full article

This paper proposes a retractable cable-driven reciprocal truss structure consisting of a cable-truss system with sliding cables and a reciprocal truss system. Adjusting the cable lengths in the cable-truss system drives the opening and closing motion, while the reciprocal truss carries the panel dead loads and live loads. The structure exploits the flexibility of cables by replacing multiple independent cables with continuous cables, thereby reducing the number of driving motors. Additionally, the cables are connected to the inner ring nodes of the triangular truss, thereby modifying the support conditions of the truss. This connection reduces the influence of external loads on structural deformation and consequently lowers the self-weight required to resist deformation, thereby helping to maintain structural stability during opening and closing. A finite element model of the structure is established using ANSYS to analyze the influence of different parameters on its mechanical performance, and the closing process is simulated by adjusting the cable lengths. Numerical results show that the proposed structure meets the design requirements. Full article

Utilizing appropriate similar materials in physical model testing is critical to ensuring an accurate simulation of the prototype mechanical behavior. For example, the physical modeling of jointed and fractured rock masses requires replicating their nonlinear mechanical characteristics. Therefore, this study develops mix proportions for a rock-like material similar to that encountered in the Xiangjiaba Hydropower Project. Based on similarity ratio analysis and mechanical testing, a jointed and fractured rock mass material was developed using a modified thin-sheet stripping method, and its nonlinear behavior was validated through mechanical experiments, numerical simulations, and distortion energy theory. The testing results of the developed similar material are as follows: (1) In specimens with single-jointed and fractured rock mass, the peak uniaxial compressive strength varies according to the joint orientation in the following order: 90° > 60° > 45° > 0° > 30°. In specimens with intersecting joints, the overall strength is primarily controlled by the orientation of the main joint, while the secondary joint plays a lesser role in further reducing the strength. (2) The analysis of distortion energy for both single-jointed and cross-jointed and fractured rock masses indicates that the crack initiation angle generally decreases with increasing joint inclination. Furthermore, at the onset of failure, the crack initiation angle in the lower part of the specimen is consistently larger than that in the upper part. The experimentally observed crack angles are in good agreement with the theoretical predictions. (3) A numerical model of the jointed and fractured rock mass was developed using the PFC2D version 5.0 discrete element software. Comparing the results of the numerical simulations and mechanical tests revealed consistent failure patterns: both exhibit the typical shear-tensile composite failure modes characteristic of jointed and fractured rock masses. These findings confirm that the developed jointed and fractured rock mass similar materials realistically capture the nonlinear mechanical behavior of fractured surrounding rock, providing a reliable material basis for the physical model testing of underground caverns. Full article

Multi-UAV cooperative path planning is an important technical basis for improving offshore emergency response efficiency in complex maritime environments. However, in complex offshore environments, cooperative trajectory planning is affected not only by geometric obstacles but also by wind disturbances, island terrain, restricted flight zones, and inter-UAV safety and communication constraints. These coupled factors make it difficult for conventional swarm intelligence optimizers to maintain risk awareness, local correction capability, and stable late-stage refinement. To address this problem, this paper proposes a risk-aware Modified Traffic Jam Optimizer for cooperative multi-UAV path planning in complex offshore missions. Unlike the original Traffic Jam Optimizer, the proposed method explicitly incorporates risk information into the population update process. A risk-opposition collaborative guidance strategy is designed to adjust the global search direction away from high-risk regions; a risk-based geometric multiscale adaptive mutation strategy is developed to identify and correct high-risk local control blocks; and a generalized quadratic interpolation decision-vector reconfiguration mechanism is introduced to refine the current best solution during stagnation or late-stage search. Two-UAV and three-UAV simulations are conducted using the constructed offshore environment and cooperative constraint models. The results show that the proposed method can generate feasible cooperative trajectories and achieve better performance than the comparison algorithms in path cost, path length, synchronized flight time, and convergence behavior. These results verify the feasibility and effectiveness of the proposed method for risk-aware multi-UAV cooperative path planning in complex offshore environments. Full article

In this study, a comprehensive stochastic and fractional-order modeling framework is developed to investigate the dynamic behavior of a shunt DC motor under random disturbances and memory effects. The motor dynamics are formulated as a system of stochastic differential equations incorporating Gaussian noise to represent uncertainties in the electrical and mechanical subsystems. The existence, stochastic ultimate boundedness, stationary distribution, and ergodic properties of the proposed model are established. To further enhance modeling capabilities, a modified Atangana–Baleanu–Caputo (mABC) fractional operator is introduced, enabling the incorporation of nonlocal memory effects inherent in electromechanical systems. The series solution is derived using the Laplace transform and the Adomian decomposition method to handle nonlinearities. Qualitative analysis of the solution is performed through fixed-point theory, while stability assessments utilize the T-Picard method. The results of the numerical simulation indicate that the stochastic model exhibits limited variability around the operating regimes, whereas the fractional-order representation is more effective at smoothing transient responses and limiting oscillatory behavior. The study proposes a realistic and adaptable method to analyze the dynamics of shunt DC motors with uncertainty and also presents useful information for the design and control of electromechanical systems. Full article

Background/Objectives: To investigate the immediate regulatory effects of magnetic stimulation with different parameters on the excitability of glutamatergic neurons and GABAergic neurons in the mouse hippocampal dentate gyrus (DG), and to analyze the underlying mechanisms using the Hodgkin–Huxley (HH) model. Methods: Whole-cell patch-clamp recordings were performed on acute brain slices to measure changes in resting membrane potential (RMP), the number of action potentials (APs) evoked by 500-ms long-duration stimulation, as well as AP threshold, peak, half-width, maximum rising slope, and maximum falling slope under magnetic stimulation at various frequencies (1, 10, 20 Hz) and intensities (50, 75 mT). An improved HH model was established based on experimental data to analyze the dynamic changes in gating variables under magnetic stimulation. Results: High-frequency magnetic stimulation (10–20 Hz) significantly increased the number of APs in both neuron types. In glutamatergic neurons, the number of APs increased from 10.12 ± 0.52 in the control group to 15.62 ± 0.84 in the 20 Hz-75 mT group; in GABAergic neurons, it increased from 7.88 ± 0.40 to 12.62 ± 0.53. Magnetic stimulation also depolarized RMP and significantly altered multiple AP waveform parameters in both neuron types. Glutamatergic neurons showed a more distinct frequency dependence, whereas GABAergic neurons were more sensitive to changes in both frequency and intensity in terms of RMP and multiple waveform parameters. Simulation results showed that the 1 Hz conditions produced negligible changes in AP firing, gating-variable dynamics, and steady-state ion-channel parameters compared with the Control condition. In contrast, high-frequency stimulation enhanced the dynamic changes of sodium and potassium channel gating variables and altered their voltage-dependent steady-state properties. Specifically, sodium channel activation shifted toward more negative potentials, whereas sodium channel inactivation and potassium channel activation shifted toward more depolarized potentials. Conclusions: Under the experimental conditions of this study, magnetic stimulation immediately enhanced the excitability of glutamatergic and GABAergic neurons in the hippocampal dentate gyrus of male mice in a frequency-dependent manner. The modified HH model reproduced both the weak effects under low-frequency stimulation and the enhanced excitability under high-frequency stimulation, suggesting that these immediate effects may be related to frequency-dependent changes in the gating kinetics and voltage-dependent properties of sodium and potassium channels. Full article

Pressure pulsations generated by pumps impair noise behaviour, increase mechanical loading, and reduce control performance in hydraulic systems. This study investigates the use of a rotary mechanical pulsation compensator integrated into the drivetrain of an external gear pump. The aim is to attenuate pulsations directly at their source without modifying the hydraulic layout. This is accomplished by using the torque induced flow rate pulsation to cancel the external flow rate excitation, which leads to destructive interference between flow rate induced and torque induced pressure pulsations. An analytical frequency domain model of the coupled mechanical–hydraulic system is derived to determine the required stiffness and damping conditions. The theoretical results are validated experimentally at mean pressure levels of 100 bar and 170 bar, both for two different hydraulic layouts. With a resonator pipeline at the pump outlet, the first harmonic of the pressure pulsation at the compensation frequency is reduced by 10.9 bar and 18.4 bar, respectively, which corresponds to reduction rates of 93% and 98%. The required damping value depends on the operating conditions, but it is independent of the hydraulic layout. While insufficient damping increases pressure pulsations around the compensation frequency, slightly higher damping flattens the frequency characteristics of pressure pulsation and reduces the maxima around the compensation frequency. In the neighbourhood of this frequency, the proposed concept enables effective reduction of the first pressure pulsation harmonic through a structural modification of the drivetrain. Full article

Localized optical absorption by nanoscale inclusions can profoundly alter energy deposition in optical traps, giving rise to nonlinear and long-timescale dynamics. Recent experiments have reported the formation of expanding optically darkened regions and episodic plasma-like emission during pulsed near-infrared optical trapping of magnetic beads interacting with biological cells. Here, we develop a reduced-order mechanistic model to investigate whether absorber-driven optical–thermal feedback associated with Fe₃O₄ inclusions is sufficient to reproduce the observed pre-plasma darkening dynamics. The model is constructed progressively from first-principles electromagnetic absorption and pulse-scale thermal diffusion to nonlinear feedback mediated by an evolving optically modified region. Single-pulse and multi-pulse simulations demonstrate that isolated iron-oxide absorbers cool too rapidly to sustain long-timescale thermal accumulation through linear heating alone. However, incorporation of a bubble-mediated optical feedback channel produces bounded growth, partial optical darkening, and slow relaxation dynamics consistent with experimentally observed minute-scale evolution. Electromagnetic absorption was computed using full core–shell Mie theory, yielding absorption cross-sections sufficient to support strong localized optical attenuation under experimentally relevant trapping conditions. The resulting reduced-order feedback framework reproduces stable growth–relaxation cycles, finite transmission plateaus, and self-limited optical darkening without requiring runaway heating or catastrophic cavitation. To evaluate the model quantitatively, simulated transmission dynamics were compared against experimentally measured normalized transmission traces digitized from previously reported optical trapping experiments. The fitted model reproduced the observed finite transmission plateau and slow post-activation relaxation with good agreement ($R^2\approx 0.86$, RMSE $\approx 1.3\times {10}^{-2}$). These results support the interpretation that experimentally observed optical darkening arises from a feedback-regulated optical–thermal process involving slowly evolving structural modification of the trapping region rather than cumulative thermal storage within isolated absorbers. The present framework provides a quantitatively constrained reduced-order description of feedback-mediated optical darkening under pulsed optical trapping conditions and establishes iron-oxide absorption as a physically plausible ignition mechanism for dark-state formation in the pre-plasma regime. Full article

Background: Traditional genotype-guided dosing often fails to predict real-time variability in the metabolic phenotype during complex polypharmacy. This secondary analysis of a retrospective cohort aims to elucidate mechanisms underlying real-time phenoconversion during antipsychotic therapy, focusing on homozygous loss-of-function CYP3A5*3/*3 non-expressors. Methods: Using an additive phenoconversion model that integrates a genotype-derived baseline with environmental modifiers for drug–drug interactions (DDI), systemic inflammation (CRP), and renal function (eGFR), we demonstrate that the expressed metabolic phenotype is a dynamic, context-dependent construct that can markedly diverge from the genotype-predicted state. Objectives: Our data show that patients with CYP3A5*3/*3 and CYP3A inhibitors (e.g., ritonavir) had a quetiapine plasma concentrations reached 1850 ng/mL, corresponding to 3.7-fold above the internationally accepted therapeutic reference range of 100–500 ng/mL. Acute systemic inflammation (CRP > 50 mg/L) induced a functional poor metabolizer phenotype (P_act < −0.9) in individuals with a genotypic normal metabolizer status. In contrast, strong inducers such as carbamazepine, phenytoin, and heavy smoking promoted an ultra-rapid metabolizer state (CL_ind > 4.0 L/h, quetiapine < 30 ng/mL), consistent with treatment failure. In this cohort, the additive P_act model showed a strong association with observed clearance and identified clinically relevant phenoconversion mechanisms not predicted from genotype alone. Conclusions: These results support a dynamic, multi-parametric approach that integrates pharmacogenomics, therapeutic drug monitoring, biomarker profiling (CRP, eGFR), and structured DDI assessment to enable higher-resolution, real-time phenotype tracking and more informed dose individualization in high-risk psychiatric polypharmacy. Full article

In this study, four types of anti-ultraviolet aging agents—layered double hydroxides (LDHs), organic montmorillonite (OMMT), titanium dioxide (TiO₂), and ultraviolet absorber (UV326)—were employed to modify asphalt. The modified asphalt samples underwent Rolling Thin Film Oven Test (RTFOT) and xenon-lamp aging treatments, and we examined the evolution of their physical properties, rheological performance, and chemical composition. A principal component analysis (PCA) model built on representativeness, discriminative power, and non-redundancy reduced the multidimensional data to two principal components, which together captured 87.540% of the total variance. The dynamic principal component trajectories, plotted from the reduced-dimension data for the unaged–short-term-aged–xenon-lamp-aged process, revealed that anti-aging agents sharing the same protection mechanism led to comparable rates of high- and low-temperature performance deterioration during xenon-lamp aging, whereas agents with different mechanisms resulted in distinctly different patterns of performance deterioration. In the critical xenon-lamp aging stage, the neat asphalt exhibited a trajectory vector change of ΔPC1 = 0.92 and ΔPC2 = 1.25, corresponding to an angle of 54°, reflecting a low-temperature degradation. By contrast, the physical shielding agents LDHs and OMMT produced much steeper trajectories with angles of approximately −80°, where ΔPC2 values rose to as high as 3.67 and 2.19 respectively despite modest reductions in overall aging. The reflective agent TiO₂ showed a more moderate angle of 84°, with ΔPC1 and ΔPC2 values of 0.16 and 1.45, indicating a slight retardation of high-temperature performance loss. Notably, the UV absorber UV326 maintained the same trajectory angle of 56° as the neat asphalt but with reduced magnitudes of ΔPC1 = 0.63 and ΔPC2 = 0.94, suggesting a balanced delay in aging without altering its relative progression. This study proposes a novel analytical framework for mechanism-based clustering analysis and the precise selection of anti-aging agents for asphalt. Full article

Water level monitoring is closely linked to the safety of production and daily activities along riverbanks, making real-time and high-precision water level measurement an urgent technical demand. The feature extraction backbone of the Unet model is modified, and the lightweight MobileNet V2 network is adopted in this paper. The constructed network achieves significantly higher computational efficiency than standard convolutions, effectively overcoming the limited real-time performance of conventional water level measurement methods. Furthermore, the coordinate attention (CA) mechanism is integrated into the skip connections of Unet to strengthen the network’s capability to extract key features for water level segmentation, thereby further improving the accuracy of water level detection. A novel piecewise linear fitting method for water level line measurement based on monocular vision is proposed, and field-measured water level data are adopted to verify the calculation results. The main achievements of the improved model include the following: (1) Compared with the baseline model, the improved model MCUnet (MobileNet V2 + CA + Unet) achieves a 5.77% increase in accuracy and a 25.71% improvement in inference speed on the experimental water surface recognition dataset. (2) Taking the field-observed water level as the reference, the mean absolute error of the proposed image-based water level monitoring method reaches approximately 1.69 cm. (3) In comparison with DeepLab, U2net and Unet, the MCUnet model gains accuracy improvements of 4.47%, 2.81% and 5.77% respectively, with the detection frame rate increased by 12 FPS, 15 FPS and 11 FPS correspondingly. Through this work, the paper can provide some theoretical support and technical references for overcoming the limitations of conventional water level measuring devices, including strict installation requirements, limited measurement precision, high deployment and maintenance costs, and cumbersome data processing. Full article

With the increasing penetration of distributed renewable energy, coordinated operation between distribution networks and multiple integrated energy microgrids (IEMs) has become increasingly important for improving operational economy and maintaining system security. To address the insufficient integration of network constraints, P2P energy sharing, and contribution-based benefit allocation, this paper proposes a hybrid game-based optimal scheduling model for multi-IEM systems under distribution network constraints. In the upper level, a Stackelberg game is established between the distribution system operator (DSO) and the multi-IEM alliance to coordinate electricity trading and distribution network operation. In the lower level, an asymmetric Nash bargaining-based cooperative game is developed to enable peer-to-peer (P2P) energy sharing and allocate cooperative benefits according to the actual energy-sharing contributions of individual IEMs. Furthermore, a distributed solution framework combining the Success-History Adaptive Differential Evolution (SHADE) algorithm and an improved alternating direction method of multipliers (ADMM) is adopted to preserve data privacy and improve computational efficiency. Case studies based on the modified IEEE 33-bus distribution system demonstrate that the proposed method eliminates voltage violations and reduces network losses by 9.0%. Meanwhile, the proposed cooperative mechanism decreases the total operating cost of the IEM alliance by 7815.8 CNY and yields a more contribution-consistent profit allocation among participating microgrids. In addition, the improved ADMM reduces computation time by 42.1% compared with the conventional serial ADMM. The results demonstrate the effectiveness of the proposed method in enhancing distribution network security, promoting renewable energy sharing, and improving the economic performance of multi-IEM systems. Full article

Modelling and quantifying human socialness onto robots remain a challenge, due to the complex mechanisms and reasoning processes that incorporate human intelligence to enable social behaviours. In this paper, we propose a novel approach of modelling human sociability in the social context of human–robot interactions by deriving the sociability score, which integrates both legible and trustable motion. To generate socially accepted motions, with potential deployment in real-time and dynamic environments, a new procedure is developed to encode human trustability onto robot motion, with the introduction of the trustability score, which explores perceived benevolence and the importance of initial trust. By applying the trust region of predictability, trustably and socially predictable trajectories are thus generated that can be identified and interpreted by humans consistently as verified by experiments. The experimental results also demonstrated that the scores computed by the proposed method can effectively capture their respective defined characteristics. Furthermore, to generate and evaluate predictable trajectories independent of other trajectories, a modified predictability score computation has been derived. Finally, as a step towards creating social intelligence, we train a deep learning-based classifier to identify socially predictable trajectories, mimicking humans’ ability to recognise such motion. Full article

Background/Objectives: The corpus luteum (CL) in the dog is the sole source of progesterone (P4) during diestrus and pregnancy, making it a key regulator of reproductive function. However, robust and functionally validated in vitro models of canine luteal cells remain limited. This study aimed to establish and characterize a reproducible primary culture system of canine luteal cells with preserved steroidogenic activity and regulatory responsiveness. Methods: Ovaries containing CLs were collected from five clinically healthy bitches undergoing routine ovariohysterectomy (OHE). Luteal tissue was mechanically fragmented and enzymatically digested using collagenase type II. Primary cultures were established using an explant-based approach and maintained in Dulbecco’s Modified Eagle Medium/Ham’s F-12 nutrient mixture (DMEM/F12) or Roswell Park Memorial Institute medium 1640 (RPMI 1640) supplemented with 20% fetal bovine serum (FBS). Cellular morphology, proliferation, expression of steroidogenic markers—steroidogenic acute regulatory protein (STAR) and 3β-hydroxysteroid dehydrogenase type 1 (HSD3B1), P4 secretion, and responsiveness to forskolin stimulation were evaluated. Results: Cultured luteal cells exhibited stable attachment, proliferation, and a predominantly spindle-shaped morphology. Both media supported maintenance of a steroidogenic phenotype, while RPMI 1640 enabled enhanced proliferation, allowing expansion up to passage three and efficient cryobanking. Cells remained functionally active, secreting progesterone for up to 28 days in vitro. Forskolin stimulation increased progesterone secretion up to 2.7-fold, confirming preserved cyclic AMP-dependent steroidogenic responsiveness. Conclusions: The canine CL is a reliable source of functionally competent luteal cells, and the established culture system represents a physiologically relevant in vitro model. To our knowledge, this is the first functionally validated in vitro model of the canine CL. This platform enables controlled investigations of luteal function, endocrine regulation, and mechanisms of P4 synthesis, supporting its application in mechanistic and translational reproductive research. Full article