Search Results (10,176)

To improve the operational efficiency of the dynamic point-the-bit rotary steerable system (DPB-RSS) in deep and complex formations, this paper proposes a build-up rate (BUR) prediction model, a trajectory control model, and a mechanism–data fusion model for rate of penetration (ROP) prediction. Validation using field data from Well A indicates that the BUR and ROP models achieve prediction accuracies of 91.45% and 91.34%, respectively, demonstrating the reliability of the proposed models. Based on the validated models, a parameter sensitivity analysis was conducted for Well B to investigate the effects of weight on bit (WOB), rotary speed, and flow rate on drilling performance, thereby identifying a recommended operational parameter combination (WOB ≥ 60 kN, rotary speed = 105 rpm, and flow rate = 65 L/s). In addition, well trajectory control was implemented by dynamically adjusting the tool face angle and steering ratio using a compound control algorithm. Field application results further indicate that the proposed scheme can improve tool performance and provide useful guidance for efficient drilling with DPB-RSS. Full article

To improve the anti-slip performance and energy-efficient torque coordination of four-wheel-drive articulated tractors operating in hilly and mountainous terrains, this study proposes an integrated control framework that combines a 7-DOF tractor dynamics model, a GA-optimized fuzzy slip-ratio controller, and a three-level dynamic torque allocation strategy. First, a control-oriented full-vehicle dynamics model is established by integrating tractor body dynamics, wheel rotational dynamics, and the Dugoff tire model. Then, a fuzzy slip-ratio controller is designed using the slip-ratio tracking error and its rate of change as inputs, and its key parameters are optimized using a genetic algorithm. On this basis, a three-level dynamic torque allocation strategy is developed to coordinate the four in-wheel motors according to wheel-load distribution and slip-related constraints. MATLAB/Simulink (version 2023a) simulations and hardware-in-the-loop (HIL) tests are carried out to validate the proposed strategy. Under the straight-line driving condition, the RMSE of the proposed GA-fuzzy controller is reduced from 0.02716 to 0.00897. Under the steering condition, the average RMSE is reduced from 0.02079 to 0.01003. In addition, under the torque-allocation validation condition, the average four-wheel RMSE is reduced from 0.29632 under equal torque allocation to 0.02159 under the proposed three-level dynamic torque allocation strategy. The results indicate that the proposed method can effectively maintain the slip ratio near its target value, suppress excessive slip and redundant torque output, and improve the anti-slip and energy-efficient performance of articulated tractors. More importantly, the study provides an integrated control framework that unifies GA-optimized slip regulation and three-level torque coordination specifically for four-wheel-drive articulated tractors. Full article

Curvature ratio (δ) governs secondary flows in gas–solid two-phase flow through bends, thereby affecting particle dynamics and leading to non-uniform wall deposition and increased erosion risk. In this study, a coupled Reynolds stress model (RSM) and Discrete phase model (DPM) framework was employed. A wall contact model incorporating adhesion, rebound, and removal mechanisms was implemented via a User-Defined Function (UDF). The spatial distribution and deposition characteristics of particles with different inertia (Stokes number range: 0.020 ≤ St ≤ 30.176) were systematically investigated in the range of δ = 2.0~3.5. The results reveal a distinct inertial dependence in particle spatial distribution: particles with St < 1 exhibit a “high-dispersion, weak-aggregation” pattern, whereas those with St > 1 form an “outer-wall agglomeration, inner-wall cavity” characteristic. As δ increases, the secondary flow intensity decreases while the effective centrifugal path lengthens. Governed by the combined effects of the effective collision coefficient (Rc) and effective adhesion rate (${\eta }_a$), particle deposition is inhibited for St < 1 but enhanced for St > 1. This study advances the understanding of deposition under geometric constraints and provides a basis for optimizing pipeline design. Full article

To address the problems of coarse grains and unsatisfactory mechanical properties of as-cast Mg-8.5Al-1Zn alloy, which hinder its application in dissolvable bridge plugs, this study took the alloy as the research object and subjected it to plastic deformation via hot extrusion with an extrusion ratio of 12. Through the use of Combined Electron Backscatter Diffraction (EBSD) and Transmission Electron Microscopy (TEM) Testing and Characterization Techniques, the macroscopic mechanical properties, microstructural evolution, and extrusion deformation mechanism of the alloy in both as-cast and as-extruded states were systematically investigated. The results indicate that hot extrusion deformation significantly enhances the comprehensive mechanical properties of the alloy. Compared with the as-cast alloy, the tensile strength, yield strength, and elongation of the as-extruded alloy are increased by 104.0%, 314.9%, and 166.7%, respectively, with the static toughness increasing by 809.1%. The as-cast alloy exhibits coarse grains, Al element segregation, and high-density dislocations. After hot extrusion, dynamic recrystallization dominates the grain refinement, reducing the grain size by approximately 60%. Solute atoms precipitate to form multiphase structures and coherent nano-scale precipitates, along with the formation of tensile twins and a weakened bimodal texture. The improved yield strength of the as-extruded alloy stems from the synergistic effect of multiple strengthening mechanisms, among which precipitation strengthening induced by nano-precipitates is the primary contributor. The enhanced plasticity is attributed to grain refinement and texture regulation. This study clarifies the extrusion deformation mechanism of the Mg-8.5Al-1Zn alloy for dissolvable bridge plugs and verifies the rationality of the hot extrusion process with an extrusion ratio of 12, providing technical support for its industrial application in dissolvable bridge plugs and the performance regulation of similar dissolvable magnesium alloys. Full article

To explore the evolutionary dynamics of green product markets under bounded rationality, this study develops a tripartite evolutionary game model involving the government, passenger vehicle enterprises, and consumers, using China’s new energy vehicle (NEV) market as a case study. By integrating system dynamics with real-world data and policies, the paper simulates strategy evolution paths and identifies equilibrium conditions. The results show a unique evolutionarily stable strategy: the government refrains from regulation, enterprises actively produce NEVs, and consumers actively purchase green products. The government’s strategy is primarily influenced by enterprises, while enterprises’ strategy is mainly driven by consumers. Numerical analysis reveals that when the premium payment ratio of green products (price difference relative to conventional vehicles) is controlled between 27.27% and 31.82%, the market evolves most rapidly toward the ideal equilibrium. Furthermore, when the additional positive benefit ratio of green consumption falls below 36.36%, market formation and development are severely hindered; raising this ratio to 40.91% yields significant promotion effects, beyond which marginal benefits diminish. These findings provide quantitative benchmarks for policy design and strategic decision-making to foster self-sustaining green product markets. Full article

Unauthorized unmanned aerial vehicles (UAVs) threaten Vehicle-to-Everything (V2X) spectrum security. Real-time edge detection faces strict hardware constraints, severe multipath fading, and Doppler distortions. This article proposes HA-EffNet, a physics-informed multi-task learning framework engineered for radio frequency (RF) sensing on roadside units (RSUs). The network restricts its temporal receptive field to align mathematically with the channel coherence time, thereby preventing deep noise overfitting. A hierarchical mechanism integrates Efficient Channel Attention (ECA) for shallow noise suppression and Receptive Field Attention (RFA) for deep signature extraction. Furthermore, the shared multi-task architecture simultaneously executes discrete classification and continuous spectral parameter regression, effectively halving computational overhead compared to redundant single-task deployments. Evaluations on the Microphase and DroneRFa datasets yield classification accuracies of 97.88% and 94.67%. Compound tests integrating Tapped Delay Line C (TDL-C) models and dynamic signal-to-noise ratio (SNR) variations validate algorithmic resilience against severe physical degradation. Utilizing a 0.12-million-parameter footprint, the network delivers a 0.84 ms inference latency and 1204.9 frames per second (FPS) throughput on the NVIDIA Jetson Orin Nano Super, providing a highly efficient edge-sensing solution. Full article

Background/Objectives: Myelodysplastic syndromes (MDS) are associated with a significant risk of progression to acute myeloid leukemia (AML), affecting approximately 30% of patients. In high-risk MDS, leukemic transformation may occur within a short time frame, highlighting the need for early and reliable biomarkers of disease progression. Increasing evidence suggests that immune dysregulation and cytotoxic T-cell dysfunction contribute to disease evolution. This study aimed to evaluate PD-1 and CD57 expressions on CD8⁺ T cells and to investigate the CD8⁺PD-1⁺/CD4⁺PD-1⁺ ratio (PERLS) as a potential immunological marker predictive of leukemic transformation. Methods: Thirty-one patients with MDS were prospectively followed over a 12-month period. At baseline, patients underwent routine clinical and laboratory evaluation, including multiparameter flow cytometric assessment of bone marrow blasts. An extended immunophenotypic analysis of bone marrow samples was performed at study entry to assess PD-1 and CD57 expression on CD8⁺ T cells. Cytogenetic and molecular analyses were conducted when clinical findings suggested disease progression. Patients who developed signs of progression were re-evaluated approximately one month later, during the progression phase, to assess dynamic immunological changes. Results: Of the thirty-one patients included, eighteen progressed to AML, whereas thirteen remained clinically stable. Patients who progressed demonstrated a significant increase in PD-1 and CD57 expression on CD8⁺ T cells compared with stable patients. Moreover, a markedly higher CD8⁺PD-1⁺/CD4⁺PD-1⁺ (PERLS) ratio was observed in patients who subsequently developed AML, particularly during the progression phase. Conclusions: Dynamic immunophenotypic monitoring reveals that increased PD-1 on CD8⁺ T cells and an elevated PERLS ratio are associated with imminent leukemic transformation in MDS. These findings support the incorporation of immune-based biomarkers, particularly the CD8⁺PD-1⁺/CD4⁺PD-1⁺ ratio, into routine risk assessment to enable earlier identification of disease progression and timely therapeutic intervention. Full article

As wildfires intensify globally due to climate change, accurate wildfire danger forecasting systems have become essential for effective disaster management and early warning. Fuel Moisture Content (FMC), defined as the ratio of water mass to dry fuel mass, plays a critical role in determining ignition probability and fire spread dynamics. This study conducts a comparative analysis of five major national wildfire danger rating systems: the National Fire Danger Rating System (NFDRS, USA), Canadian Forest Fire Danger Rating System (CFFDRS), European Forest Fire Information System (EFFIS), Australian Fire Danger Rating System (AFDRS), and the Korean Forest Fire Danger Rating System (KFDRS). Using a multi-criteria comparative framework, the systems were evaluated based on fuel classification structure, input variables, modeling approach, and spatiotemporal prediction resolution. The results reveal substantial disparities in spatial resolution (100 m to district-level), temporal resolution (hourly vs. daily), and fuel moisture modeling approaches (physics-based, index-based, and hybrid systems). Specifically, NFDRS and AFDRS provide high-frequency forecasting with hourly temporal resolution, operating at spatial resolutions of 1 km and 100 m, respectively, and incorporating dynamic fuel moisture modeling. In contrast, CFFDRS and KFDRS primarily rely on daily index-based predictions. Furthermore, while many global systems increasingly leverage remote sensing and machine learning for real-time FMC estimation, South Korea’s KFDRS remains predominantly empirical and weather-driven. The analysis identifies critical limitations in the KFDRS, including coarse spatial resolution (district-level), limited integration of Live Fuel Moisture Content (LFMC) modeling, and the lack of AI-augmented hybrid approaches. Accordingly, this study proposes a phased three-stage policy roadmap (2026–2035), emphasizing sensor-network expansion, AI–physics fusion modeling, and high-resolution (10 m) FMC mapping to enhance forecasting accuracy in complex terrains. These findings provide strategic insights for improving wildfire risk management and supporting the transition from reactive response to predictive wildfire forecasting under increasing climate variability. Full article

The size-dependent out-of-plane vibrational behavior of graphene-based nanoelectromechanical (NEMS) resonators is investigated using a molecular mechanics (MM) finite element approach. Each carbon–carbon (C–C) bond is modeled as an Euler–Bernoulli beam element, with the bending stiffness derived from the bond-angle potential, yielding an equivalent plate flexural rigidity D = (√3/6) kθ. The natural frequencies of the first four vibration modes are computed for square graphene sheets of increasing size with both zigzag (ZZ) and armchair (AC) chirality configurations under simply supported boundary conditions on all four edges. A chirality-induced frequency deviation δ(L) is defined to quantify the difference between ZZ and AC results, and a threshold size L* is identified as the sheet size at which δ falls below 1%. For mode 1, the threshold is L* = 18.5 nm; the values increase monotonically to 24.5 nm, 28.0 nm, and 31.5 nm for modes 2 through 4, indicating that higher modes require larger sheet dimensions before continuum plate theory becomes reliable. A dimensionless frequency parameter Ω = f_MM/f_CT is introduced to directly compare MM predictions with the Kirchhoff plate theory analytical solution, and the AC frequency ratio Ω = f_MM/f_CT is shown to converge toward unity with increasing sheet size. The present results provide quantitative design guidelines for graphene NEMS resonators and establish the minimum device dimensions for which isotropic continuum models yield accurate dynamic predictions. Full article

Background/Objectives: Cardiovascular complications remain the leading cause of mortality among patients with end-stage renal disease (ESRD) treated with maintenance hemodialysis (HD). Global longitudinal strain (GLS) is a sensitive echocardiographic marker of left ventricular systolic dysfunction that enables the detection of transient contractile abnormalities consistent with intradialytic myocardial stunning. This study aimed to assess intradialytic GLS dynamics during a single HD session and to identify predictors of GLS deterioration. Methods: Forty-three patients were enrolled. Transthoracic echocardiography, electrocardiography, and pulse wave analysis were performed before HD, at mid-session, and after HD. Biochemical assessment included, among others, plasma osmolality, electrolytes, and biomarkers of oxidative stress and endothelial dysfunction. Results: Three distinct intradialytic GLS trajectories were identified: GLS worsening (GLSw, 46.5%), GLS stable (GLSs, 34.9%), and GLS improvement (GLSi, 18.6%). In the GLSw group, independent predictors of GLS deterioration included a decrease in left atrial volume index (LAVI, p = 0.0002), an increase in left ventricular end-systolic volume index (LVESVI, p = 0.0067), diabetes mellitus (p = 0.0094), and an increase in the malondialdehyde-to-creatinine ratio (MDA/CREA, p = 0.0055). In the GLSi group, GLS improvement was associated with a decrease in plasma osmolality (p = 0.0326) and asymmetric dimethylarginine (ADMA, p = 0.0279), as well as an increase in the subendocardial viability ratio index (SEVRI, p = 0.0004) and caspase-1 (p = 0.0005). Conclusions: Intradialytic GLS trajectories are heterogeneous and reflect individual susceptibility to GLS deterioration. Modifiable adverse factors likely include oxidative stress, osmotic stress, fluid overload, uremic toxin- and ion-disturbance-related stress, and impaired coronary microvascular reserve. Future prospective studies are needed. Full article

The Hubei carbon emissions trading market presents significant price volatility driven by energy price fluctuations, macroeconomic conditions and policy changes. Accurate price risk measurement is critically important for market participants. This study adopts Value at Risk (VaR) and Expected Shortfall (ES) to quantify market risk, and constructs a set of DCS-type models by combining the dynamic conditional score framework with the skewed Student-t distribution. Model evaluation covers unconditional coverage test, conditional coverage test, dynamic quantile test, the Actual-to-Expected ratio, the mean and the maximum absolute deviation, quantile loss and FZ loss. Empirical analysis based on daily HBEA spot prices from 3 April 2014 to 4 December 2024 shows that: (1) The DCS-ST model provides better data fitting performance and can effectively measure the market risk of China’s carbon trading market. (2) The parameter updating frequency has little impact on the prediction accuracy of the model. The results enriches the quantitative methodology for carbon market risk measurement and provide a reliable technical scheme for tail risk management in China’s carbon emissions trading market. Full article

This paper studies the dynamic behavior of a catamaran hovercraft wind farm service vessel (CHWFSV) during the berthing coupling process with a wind turbine tower, aiming to enhance its safety and reliability in engineering applications. By constructing an arc-shaped elastic fender and employing computational fluid dynamics (CFD), it investigates the motion response under transverse waves considering the effects of thrust, air-cushion flow and the elasticity coefficient of the fender. A finite element analysis (FEA) model of the arc-shaped fender, accounting for elastic stress and strain, is developed to study its coupled mechanical behavior under different thrust conditions. The research in this paper is based on numerical CFD simulation with experimental validation. The motion modeling under transverse waves is further verified through uncertainty analysis. The series of research results indicate the following: vessel rolling resonance occurs at λ/L = 1.667 (λ/L denotes the dimensionless wavelength-to-length ratio); increasing air-cushion flow extends the roll period and reduces roll amplitude at λ/L = 0.667, while applying thrust at λ/L = 1.667~3 lowers roll but reduces pitch and heave stability; relatively good berthing performance is achieved when F_CM/∆ = 0.054 and the elastic coefficient is 1.25 × 10⁷ Pa/m (Δ represents the vessel weight). Full article

This paper describes two front-end architectures developed in a 28 nm CMOS process for the readout of pixel detectors in future high-energy physics (HEP) colliders and advanced X-ray imaging instrumentation. The front-end channels have been developed in the framework of the PiHEX project, funded by the Italian Ministry of University and Research. PiHEX aims to improve the state of the art of pixel readout chip technology in high-luminosity colliders and X-ray imagers in the next generation of free electron lasers (FELs) by developing, in 28 nm CMOS technology, the fundamental microelectronic building blocks for pixel readout chips. Such blocks, also implementing innovative circuit ideas, will enable, in future applications, the integration of large-scale readout chips, meeting a set of challenging requirements, such as high spatial resolution, high signal-to-noise ratio, very wide dynamic range and the capability to withstand unprecedented radiation levels. Two different front-end channels were designed, integrated into two prototype chips, and tested. One architecture, featuring a pixel size of 25 µm × 100 µm, was optimized for tracking applications in high-energy physics experiments, like the ones that take place at CERN in the high-luminosity upgrade of the Large Hadron Collider (LHC), while the second one, featuring a pixel size of 110 µm × 55 µm, was devised for X-ray imaging applications in FELs. Full article

Urban green spaces are increasingly recognized as key elements of sustainable urban development; however, their economic implications, particularly for labor productivity, remain underexplored in developing countries. This study examines the impact of urban green spaces on labor productivity across 92 Indonesian cities over the period 2014–2024, while accounting for spatial dependence and dynamic effects. Urban green space is measured using the Normalized Difference Vegetation Index (NDVI), and labor productivity is defined as the ratio of regional economic output to employment. The analysis incorporates control variables including life expectancy, environmental quality (AOD), average years of schooling, and GDP per capita. To address spatial and temporal dynamics, this study employs a Spatial Dynamic Panel Data (SDPD) framework. The results show that urban green spaces have a positive and significant effect on labor productivity. In addition, spatial spillover effects are evident, indicating that productivity in one city is influenced by conditions in neighboring areas. Socio-economic factors, particularly health, education, and economic development, also play a significant role. These findings highlight the economic relevance of urban green infrastructure and underscore the importance of integrating environmental considerations into urban policy to enhance productivity in developing country contexts. Full article

In earthquake engineering and hydraulic engineering, the dynamic mechanical behavior of cohesive soils is crucial to ensure structural stability. However, most existing dynamic constitutive models fail to adequately account for the influence of strain history, which is essential for accurately predicting soil behavior under seismic loading. This study conducted a series of cyclic single-shear tests on both in situ and disturbed Changsha cohesive soils. Hysteresis curves were obtained under varying shear strain amplitudes to investigate the degradation patterns of the dynamic shear modulus and the evolution of the damping ratio. Furthermore, multi-cycle loading tests under constant strain amplitude were carried out to clarify the correlation between damping ratio, dynamic shear modulus, and the number of loading cycles. A simplified practical dynamic model, applicable to general cohesive soils, is proposed. This model incorporates the effect of strain history and provides a valuable reference for analyzing the dynamic response of soils subjected to earthquake actions. Full article