Search Results (186,254)

Physically consistent estimation of soft-tissue mechanical properties is critical for surgical robotics, intraoperative safety monitoring, and simulator initialization, yet existing methods typically require force-sensing hardware or manual parameter tuning. This paper presents a physics-informed generative framework that estimates tissue stiffness ($k_s$), damping coefficient ($k_d$), and tool–tissue contact force magnitude ($F_{mag}$) from monocular laparoscopic video in a label-free manner with respect to mechanical parameters and interaction forces. The pipeline integrates three components: DepthPro, a multi-scale Vision Transformer (ViT) for zero-shot metric depth estimation; a 3D geometric contact detection pipeline; and a dual-mode conditional generative network trained via a five-term physics–adversarial loss. A differentiable Mass–Spring–Damper (MSD) simulator is embedded directly in the training loop. This enables gradient-based parameter learning without force-sensor, displacement, or boundary-condition supervision. Parameter identifiability is supported through dual observational grounding: MSD physics consistency against observed contact displacement, and next-frame depth map reconstruction. Validated on CholecSeg8k cholecystectomy sequences, Physics-Informed Neural Network (PINN)-estimated parameters significantly outperform static literature baselines (Wilcoxon p = 2.49 × 10⁻⁸, Cohen’s d = 0.374), with physically plausible viscoelastic settling dynamics recovered within 0.9 s of tool release. Since no force sensors were present at acquisition time, evaluation follows an indirect simulation-consistency protocol. Mechanical parameters are estimated at 1.6 ms/frame, a negligible addition to the monocular depth front end that sets the pipeline rate. Estimated parameters directly enable stiffness-aware haptic rendering, intraoperative safety monitoring, and scene-adapted surgical simulation initialization. Full article

The surging integration of volatile renewable energy severely exacerbates power grid frequency fluctuations, yet conventional frequency regulation (FR) market clearing mechanisms fail to efficiently coordinate heterogeneous energy storage systems (ESSs) due to the complete decoupling of multi-dimensional physical performance from economic dispatch. To resolve this critical industry bottleneck, this paper proposes a novel Stackelberg game-based clearing mechanism tailored for diverse ESS participation. A bi-level optimization framework is constructed to internalize physical FR characteristics into market economics; the upper level minimizes the system operator’s total procurement costs by transforming multi-dimensional physical metrics—including dynamic response rates, time delays, and control accuracy—into endogenous performance penalty factors. Concurrently, the lower level maximizes the individual revenues of heterogeneous ESS aggregators under a Gini coefficient-based fairness constraint to mitigate profit monopolization and promote a more sustainable market ecology. To address the computational challenges of high-dimensional non-convexity, an enhanced hybrid Genetic Algorithm and Quadratic Programming (GA-QP) solver is developed to secure robust convergence to the Stackelberg equilibrium. Comprehensive simulation results confirm that the proposed Stackelberg game-based clearing mechanism enables a highly rational, quality-driven allocation of frequency regulation capacity. By dynamically linking physical performance metrics with economic benefit factors, it successfully achieves an optimal balance of interests between heterogeneous energy storage aggregators and the overarching market. Crucially, compared to conventional purely economic models, this mechanism structurally prevents absolute technology monopoly—drastically reducing the market Gini coefficient from a hazardous 0.85 to a healthy 0.32—while sustaining multi-party equity at a negligible system cost increase of only 1.64%. Ultimately, this framework offers a highly feasible and resilient solution for the efficient clearing of multi-type energy storage in modern power systems. Full article

Clarifying SOC sequestration via physical and microbial processes is key for improving farmland fertility, yet the relative contributions of agronomic practices to carbon fractions and aggregate sizes remain unclear. This study (2010–2019, rice–wheat rotation, Funiu Mountain eastern plain, central China) examined tillage and organic amendment effects on SOC dynamics and underlying mechanisms across aggregate sizes under six treatments (conventional/reduced tillage with no fertilizer, chemical fertilizer, or organic manure). SOC, particulate organic carbon (POC), and mineral-incorporated organic carbon (MOC) were measured in bulk soil and water-stable aggregates (>2000, 250–2000, 53–250, <53 μm), and physical fractionation and phospholipid fatty acid (PLFA) analysis were conducted to assess interactions among aggregates, carbon quality, and microbial communities. Results showed that, compared with conventional tillage without fertilization, both conventional tillage and reduced tillage with organic manure significantly increased bulk SOC by 92–122% and macroaggregate (>250 μm) mass by 15–110%. The combined application of organic manure and reduced tillage redirected SOC from micro- to macroaggregates. Moreover, POC and MOC were the primary contributors to bulk SOC, with POC showing a strong direct effect on SOC accumulation. Furthermore, a positive priming effect was detected exclusively in macroaggregates, identifying them as key sites for SOC turnover and confirming that optimized tillage with manure shifts aggregates to larger sizes and boosts SOC through physical protection. The micro-to-macro cascade offers a robust framework for SOC dynamics, and its persistence under diverse climates warrants future research for sustainable management. Full article

Overhanging parapets are commonly adopted in vertical breakwaters to reduce wave overtopping. However, previous studies have shown that these structures may also be subjected to significant impulsive loads associated with the Confined-Crest Impact (C-CI) phenomenon. While the loading mechanisms of conventional recurved parapets have been extensively investigated, the influence of alternative overhanging geometries on both wave loading and overtopping reduction remains poorly understood. This study investigates the hydraulic efficiency and wave loading on rectilinear, recurved, and recurved crownwall under non-breaking wave conditions by means of Reynolds-Averaged Navier-Stokes (RANS) simulations coupled with a Volume of Fluid (VOF) approach. The results show that parapet geometry strongly influences both dynamic/impulsive wave loading and overtopping volumes. The recurved crownwall achieves the greatest overtopping reduction but also the highest force amplification. Conversely, the recurved parapet produces the lowest impulsive loads among the tested overhanging geometries, at the expense of hydraulic efficiency, although these loads remain higher than those experienced by the reference vertical parapet. These findings reveal a trade-off between overtopping mitigation and structural loading, indicating that the most hydraulically effective geometry is not necessarily the most structurally advantageous. Full article

The main objective of this study is to obtain the average parameters of gas-discharge plasma when controlling the steady position of the bow shock wave (BSW) using the combined action of a gas discharge initiated by a current from an external source and a magnetic field near the frontal surface of the model. The studies were carried out using both experimental and numerical methods in xenon and air. A comparison of the numerical and experimental dependences of the relative distance of the steady BSW from the model on the discharge power showed good agreement. Based on the conducted flow modeling, taking into account the dependence of the adiabatic index on the degree of ionization and the degree of nonequilibrium, and using the theory of Burm et al., gas-discharge plasma characteristics were obtained, such as the degree of ionization and the degree of nonequilibrium, the electron density and the electron temperature in the absence and presence of a magnetic field. By this way an integrated experimental–computational system was formed in which the measured characteristics of the discharge and BSW, as well as the numerically obtained averaged plasma parameters in the impact zone, are combined with the theory of Burm et al. to clarify the thermodynamic state of the medium and determine the corresponding characteristics of the gas-discharge plasma. The obtained results can be used for assessing the characteristics of plasma gas dynamic and magnetohydrodynamic phenomena in high-speed flows; for example, in the development of control systems that take into account the influence of plasma parameters and the electric and magnetic fields. Full article

Semi-active suspension systems combine low power consumption, rapid response, and fail-safe operation by reverting to passive mode after control failure, making them important for intelligent chassis and vibration-control systems. With the development of intelligent actuators, nonlinear modeling, and advanced control methods, this technology is expanding from conventional road vehicles to off-road vehicles and agricultural machinery. Compared with passenger cars, agricultural machinery faces stronger random excitation, time-varying loads, muddy environments, resource-constrained controllers, and requirements for operational accuracy. This review focuses on semi-active damping and vibration-isolation systems for off-road and agricultural applications. Mainstream actuators, control-oriented nonlinear damper models, classical, robust, and adaptive control methods, MPC, DRL, and mechanism–data fusion control are compared in terms of hardware constraints, model accuracy, real-time computation, and agricultural adaptability. Applications in seat/cab isolation, tractor and tracked chassis systems, rollover prevention, and precision implements are summarized. The review shows that semi-active suspension in agricultural machinery is evolving beyond the conventional trade-off between ride comfort and handling stability toward multi-objective coordination of safety, ground-contact stability, operational accuracy, operator protection, and energy consumption. Full article

Aluminum honeycomb structures are widely used in the aeronautical, aerospace, marine, and automotive industries due to their excellent stiffness-to-weight ratio. However, machining these structures remains highly challenging because their thin, highly flexible cell walls are susceptible to plastic deformation and geometric defects. To overcome these limitations, this study proposes an innovative machining approach that combines longitudinal-torsional ultrasonic vibration-assisted machining (LT-UVAM) with a 55-tooth CZD10 cutting tool. A three-dimensional finite element model was developed using Abaqus/Explicit 2017 to simulate the dynamic interactions between the cutting tool and the honeycomb cell walls during the milling process. Following experimental validation on a high-speed machining center, the model was employed to investigate the effects of cutting and vibration parameters on the machining performance. The results demonstrate that longitudinal-torsional ultrasonic vibration coupling significantly reduces the cutting forces, resulting in a 26% to 42% reduction in the axial force component (Fz). Furthermore, vibration assistance effectively limits cell wall deflection, reducing the stress levels by up to 60% in the thinnest walls while maintaining them below the critical Euler buckling load. Furthermore, an ultrasonic vibration frequency of 22.5 kHz almost completely eliminates plastic deformation, while a vibration amplitude of 25 µm significantly reduces tool wear by promoting intermittent tool–workpiece contact, thereby facilitating chip evacuation. Ultimately, the LT-UVAM process produces finer and more uniform chips, leading to improved machining quality, enhanced dimensional accuracy, and extended tool life. Full article

Background: This study investigates the psychophysiological stress profiles of professional basketball players by simultaneously analyzing two distinct neuroendocrine pathways: the sympathetic–adrenal–medullary (SAM) system, via salivary alpha-amylase (AA), and the hypothalamic–pituitary–adrenal (HPA) axis, via salivary cortisol (C). While competitive environments are known to elicit significant stress, the interaction between game-specific variables—such as playing time (PT) and tactical position—and those biomarkers remains insufficiently explored in real-time, official match settings. Methods: Twelve professional male basketball players were monitored across four official matches. Salivary samples were collected, and stress biomarkers (AA and C) were analyzed at three timepoints: pre-match, half-time, and post-match. Results: Results indicate that stress responses are non-uniform and highly context-dependent. A significant spike in AA was observed during the first match (p < 0.001; ES = 0.82; 95% CI −0.01–1.66), where concentrations rose from a pre-match mean of 247.9 ± 232.59 U/mL to a post-match peak of 674.39 ± 693.33 U/mL. Cortisol responses did not vary significantly across matches but exhibited a strong positive correlation with PT (p = 0.01; R = 0.76), identifying that C may serve as a primary marker of individual physical workload. Positional analysis revealed significant divergence in HPA activation; guards (0.55 ± 0.31 µg/dL) and centers (0.51 ± 0.22 µg/dL) exhibited higher cortisol levels compared to forwards (0.24 ± 0.18 µg/dL), reflecting the high cognitive/decision-making load of guards and the mechanical/physical contact load of centers. Conclusions: The observed differences in AA and C liberation suggest that stress responses during matches are influenced by a complex interaction of physiological and psychological stimuli characteristic of competitive basketball. Consequently, these findings indicate the importance and value of a dual-biomarker approach which might provide a framework for optimized training load management and recovery protocols in elite basketball. Full article

To preliminarily elucidate the bidirectional metabolic effects caused by changes in PFKM expression, provide research clues for further investigation of the molecular mechanisms through which PFKM regulates porcine skeletal muscle metabolism and myogenic differentiation, and offer a reference for identifying candidate genes associated with meat production traits and studying gene regulation in pig breeding, this study compared skeletal muscle protein expression profiles between Large White and Bama pigs. Candidate regulatory factors related to muscle growth and energy metabolism were screened, and the effects of altered muscle-type phosphofructokinase (PFKM) expression on metabolic homeostasis and myogenic differentiation in porcine skeletal muscle satellite cells (SMSCs) were preliminarily evaluated. Longissimus dorsi muscle tissues from Large White and Bama pigs were analyzed using iTRAQ-based proteomics. A total of 2040 reliably quantified proteins were identified, of which 51 were relatively upregulated in Large White pigs and 73 were relatively upregulated in Bama pigs. Functional enrichment analysis showed that the differentially expressed proteins were mainly involved in glycolysis, mitochondrial energy metabolism, protein synthesis, and the regulation of muscle fiber structure and function. PFKM was therefore selected as a key candidate differentially expressed protein. Porcine SMSC models comprising a PFKM knockdown group (PFKM-KD), a PFKM overexpression group (PFKM-OE), and a normal control group (PFKM-CON) were subsequently established. Glucose consumption and lactate accumulation in the culture medium, ATP levels, reactive oxygen species (ROS), mitochondrial membrane potential, apoptosis, mitochondrial dynamics-related proteins, and myogenic differentiation markers were then examined. Compared with the PFKM-CON group, the PFKM-OE group showed significantly increased glucose consumption and lactate accumulation, together with significant increases in ROS levels, mitochondrial membrane potential, and apoptosis, whereas ATP levels were significantly reduced. In the PFKM-KD group, glucose consumption and lactate accumulation were significantly decreased, accompanied by reductions in mitochondrial membrane potential, ROS, ATP levels, and apoptosis. PFKM overexpression mainly induced oxidative stress, ATP depletion, and increased apoptosis, whereas PFKM knockdown primarily reduced mitochondrial membrane potential, ROS, and ATP levels, indicating a relatively low-metabolic state. Both treatments were accompanied by dysregulated expression of the mitochondrial dynamics-related proteins DRP1, MFN2, and OPA1, although their patterns of change were not identical. Western blotting and immunofluorescence consistently showed that the expression levels of the myogenic differentiation markers MyoD and MYH were significantly lower in both the PFKM-KD and PFKM-OE groups than in the control group, suggesting that either excessive or insufficient PFKM expression may impair the myogenic differentiation potential of SMSCs. In conclusion, changes in PFKM expression are closely associated with glycolysis-related metabolism, energy and redox homeostasis, mitochondrial function-related indicators, and myogenic differentiation capacity in porcine SMSCs. The normal biological function of PFKM may therefore depend on its expression being maintained within an appropriate range. Full article

In the context of global climate issues and the transition towards sustainable development, this study examines the relationship between environmental cost, public expenditure, energy structure, and institutional quality in Saudi Arabia over the period 1994–2023, where environmental cost is proxied by the carbon intensity of GDP. To capture both long-run relationships and short-run dynamics, the study applies the Autoregressive Distributed Lag (ARDL)-Error Correction Model (ECM) framework. The results confirm the existence of a stable long-run equilibrium relationship among the variables. Public expenditure and energy use significantly increase carbon intensity, indicating that fiscal expansion and energy intensity remain important sources of environmental pressure. In contrast, renewable electricity generation and improvements in institutional quality significantly reduce carbon intensity, highlighting the importance of clean energy deployment and effective governance. Economic growth exhibits a small but statistically significant negative effect on carbon intensity, suggesting gradual progress toward relative decoupling between economic activity and environmental cost. The error-correction coefficient indicates rapid adjustment toward the long-run equilibrium following short-run shocks. These findings provide policy-relevant evidence for aligning fiscal policy, energy transition strategies, and institutional reforms with Saudi Arabia’s Vision 2030 and broader sustainability objectives in resource-dependent economies. Full article

Background: Cyclin-dependent kinase 4 (CDK4) is a key regulator of cell-cycle progression and an established therapeutic target for breast cancer. Although the unique architecture of its ATP-binding site has enabled the development of highly selective inhibitors, the emergence of acquired resistance highlights the need for alternative therapeutic strategies targeting protein conformational regulation. Methods: The conformational landscape of CDK4 was investigated in this study using accelerated molecular dynamics (aMD) simulations combined with Markov state model (MSM) analysis to identify cryptic conformational states and potential allosteric binding sites. Particular attention was given to the glycine-rich loop (G-loop), a critical structural element that shapes the ATP-binding pocket, and to the effects of compound 8i (1-(2-(3-chlorobenzoyl)hydrazine-1- carbonyl)-N-(pyridin-3-yl)pyrrolidine-2-carboxamide), previously synthesized in our laboratory, on CDK4 dynamics. Results: A distinct conformational transition was identified in which the G-loop shifted toward the N-terminus, resulting in the exposure of a previously unrecognized allosteric pocket adjacent to the catalytic site. Compound 8i interacted with Leu147 and was associated with stabilization of conformational states that favor exposure of the cryptic pocket. Conclusions: These observations suggest that ligand binding may modulate the conformational landscape of CDK4 and favor formation of a cryptic pocket with potential allosteric characteristics. The identified conformational mechanism provides new insights into the dynamic regulation of CDK4 and suggests that stabilization of transient allosteric states represents a promising strategy for the rational design of next-generation CDK4 inhibitors with the potential to overcome resistance in breast cancer therapy. Full article

The rhizosphere, the zone around the roots of plants, including the root, the soil on the root itself, and the surrounding area soil, is the hotspot for the production of reactive oxygen species (ROS). Functioning as redox signaling mediators, rhizosphere ROS regulate a series of key processes in the rhizosphere microenvironment. These biological and geochemical events cover root morphogenesis, the formation of beneficial plant–microbe symbioses, and element biogeochemical transformations. Nevertheless, the pronounced spatial heterogeneity, drastic redox fluctuations, and intricate interfacial interactions within the rhizosphere impede accurate in situ detection of ROS. Beyond technical barriers, the coupled regulatory effects exerted by biotic and abiotic factors on ROS dynamics, together with the associated ecological outcomes induced by rhizosphere ROS, remain difficult to fully disentangle. This review first discusses updated strategies and optimized methodologies for in situ rhizosphere ROS monitoring. We then characterize the spatial distribution patterns and microscale hotspots of rhizosphere ROS. Importantly, this review dissects the complex coupled regulatory network formed by biotic, abiotic, and environmental factors and molecular regulatory pathways that control ROS production. Furthermore, this study systematically illustrates diverse environmental effects triggered by rhizosphere ROS. Finally, the present work identifies prevailing research gaps and unresolved limitations in current studies. On this basis, we further propose targeted research directions for future studies in this field, providing comprehensive theoretical evidence to deepen the understanding of rhizosphere ROS formation and their mediated biogeochemical processes. Full article

Land-cover-based ecosystem service valuation commonly assigns a uniform value coefficient to pixels within the same land-cover class, thereby overlooking ecological heterogeneity in mountainous protected areas. This study developed an improved remote sensing ecological index (IRSEI) and applied it as a spatial adjustment factor in the equivalent factor method to assess ecosystem service value (ESV) changes in the Qionglai Mountains section of Giant Panda National Park, China, between 2017 and 2022. IRSEI integrated the normalized difference vegetation index, wetness, normalized difference built-up and soil index, land surface temperature, and cumulative dynamic habitat index derived from the fraction of absorbed photosynthetically active radiation. DHI-cum was included as a proxy for annual cumulative vegetation productivity and habitat energy availability rather than a direct measure of biodiversity or giant panda habitat quality. Total ESV increased from 3.27 × 10⁸ CNY in 2017 to 4.25 × 10⁸ CNY in 2022, representing an increase of 9.79 × 10⁷ CNY, or 29.98%. Water bodies contributed the largest absolute increase, rising by 4.79 × 10⁷ CNY, or 42.45%, whereas farmland showed the highest relative increase of 45.35%. Woodland remained the dominant contributor to total ESV. Spatially, ESV was higher in the northern and southern parts and lower in the central region. All corrected sensitivity coefficients were below one, indicating that total ESV responded inelastically to ±50% perturbations of individual land-cover value coefficients. The framework improves within-class spatial differentiation of ESV and may support targeted management of mountainous protected areas, although field-based habitat and biodiversity data are needed for further validation. Full article

We investigate a lensless Airy-type optical beam generated by direct Fresnel propagation of a Gaussian apodized real space cubic phase. Starting from the scalar Fresnel diffraction integral, we derive a closed-form expression showing that the propagated field can be written in terms of an Airy function, but with an argument different from that of the conventional finite energy Airy beam. This difference leads to distinct free space dynamics: the conventional beam is already formed at the input plane and follows a parabolic trajectory, whereas the lensless beam forms during propagation and undergoes stronger transverse reshaping and broadening. The two fields are also compared under atmospheric turbulence using a phase screen approach and multiple performance metrics. The comparison shows that no single beam performs best for all detection scenarios: the lensless field gives lower scintillation at the beam maximum, the two beams provide comparable aperture collected power, and the conventional Airy beam gives higher coherent fiber coupling efficiency. Full article