Search Results (352)

Autonomous mobile robots require efficient path planning algorithms for navigation in grid-based environments. While the A* algorithm guarantees optimally short paths using admissible heuristics, it exhibits path degeneracy: multiple geometrically distinct paths often share identical length. Classical A* arbitrarily selects among these equal-cost candidates, frequently producing trajectories with excessive directional changes. Each turn induces deceleration–acceleration cycles that degrade energy efficiency and accelerate mechanical wear. To address this, we propose Turn-Minimizing A* (TM-A*), a lexicographic optimization approach that maintains distance optimality while minimizing cumulative heading changes. Unlike weighted-cost methods that require parameter calibration, TM-A* applies a dual-objective framework: distance takes strict priority, with turn count serving as a tie-breaker among equal-length paths. A key contribution of this work is the explicit guarantee that the generated path has the minimum number of turns among all shortest paths. By formulating path planning as a lexicographic optimization problem, TM-A* strictly prioritizes path length optimality and deterministically selects, among all equal-length candidates, the one with the fewest directional changes. Unlike classical A*, which arbitrarily resolves path degeneracy, TM-A* provably eliminates this ambiguity. As a result, the method ensures globally shortest paths with minimal turning, directly improving trajectory smoothness and operational efficiency. We prove that TM-A* preserves the O(|E|log|V|) time complexity of classical A*. Validation across 30 independent Monte Carlo trials at resolutions from 200 × 200 to 1000 × 1000 demonstrates that TM-A* reduces turn count by 39–43% relative to baseline A* (p < 0.001). Although the inclusion of orientation expands the search space four-fold, the computation time increases by only a factor of approximately 3 (≈200%), indicating efficient scalability relative to problem complexity. With absolute latency remaining below 3300 ms for 1000 × 1000 grids, the approach is highly suitable for static global planning. Consequently, TM-A* provides a deterministic and scalable solution for generating smooth trajectories in industrial mobile robot applications. Full article

Urban intersections are critical nodes for roadway safety, congestion management, and autonomous vehicle coordination. Traditional traffic control systems based on fixed-time signals and static sensors lack adaptability to real-time risks such as red-light violations, near-miss incidents, and multimodal conflicts. This study presents a grid-enabled framework integrating computer vision and machine learning to enhance real-time intersection intelligence and road safety. The system overlays a computational grid on the roadway, processes live video feeds, and extracts dynamic parameters including vehicle trajectories, deceleration patterns, and queue evolution. A novel active learning module improves detection accuracy under low visibility and occlusion, reducing false alarms in collision and violation detection. Designed for edge-computing environments, the framework interfaces with signal controllers to enable adaptive signal timing, proactive collision avoidance, and emergency vehicle prioritization. Case studies from multiple intersections typical of US cities show improved phase utilization, reduced intersection conflicts, and enhanced throughput. A grid-based heatmap visualization highlights spatial risk zones, supporting data-driven decision-making. The proposed framework bridges static infrastructure and intelligent mobility systems, advancing safer, smarter, and more connected roadway operations. Full article

The presence of multiple permanent magnet synchronous generators (PMSGs) results in a highly complex and high-dimensional wind-farm model, making its transient synchronizing stability characteristics insufficiently understood and difficult to analyze. This paper investigates the mechanism by which interactions among multiple wind generators trigger transient synchronizing instability in wind farms. First, considering the influence of line impedance ratios, a reduced single-machine aggregated model suitable for transient synchronizing stability analysis of a wind farm with multiple PMSGs was derived from the similarity normalization transformation of the state-space matrices. Based on the aggregated model, the concepts of equivalent accelerating area and equivalent decelerating area were introduced to evaluate transient synchronizing stability of the wind farm. Through a comprehensive analysis of the effects of the generator dynamics, number of generators, network topology, and system parameters on these indices, the mechanism by which multi-PMSG interactions induce transient synchronization instability in PMSG wind farms is revealed. Finally, case studies were conducted to validate the accuracy and applicability of the analysis. Full article

Background/Objectives: Antepartum computerized cardiotocography (cCTG) represents an essential tool for assessing fetal well-being. This study aimed to comparatively evaluate antepartum cCTG-derived indices across high-risk pregnancies to identify distinctive fetal autonomic and reactivity profiles. Methods: A comparative analysis of antepartum cCTG parameters was conducted. The cohort included pregnancies beyond 28 weeks of pregnancy, 169 cases of hypertensive disorders of pregnancy (HDP), 146 of gestational diabetes mellitus (GDM), 86 of intrahepatic cholestasis (ICP), and 87 low-risk pregnancies as controls. Results: Baseline FHR remained within the physiological range across all groups (110–160 bpm; p > 0.05). Dynamic cCTG parameters exhibited clear pathology-dependent alterations. Short-term variability (STV) showed a stepwise decline from controls to ICP and GDM, reaching its lowest values in HDP (mean 1.08 bpm; p < 0.00001), accompanied by an increased proportion of epochs with STV < 1 bpm. Long-term variability suppression (LTV < 5 bpm) was significantly higher in GDM and HDP (p = 0.0077). Acceleration frequency decreased across all pathological groups, with the most pronounced reduction observed in HDP, whereas fetal movements were paradoxically elevated in both GDM and HDP. Total decelerations were more frequent in ICP and HDP; however, repetitive, late, prolonged, and >5 min decelerations remained rare and did not differ significantly between groups. Conclusions: HDP showed the most unfavorable cCTG profiles, consistent with impaired fetal autonomic regulation and chronic subclinical hypoxemia. GDM and ICP had moderate changes, suggesting milder adaptive responses. These findings emphasize the value of quantitative cCTG in differentiating fetal autonomic patterns in high-risk pregnancies and the importance of tailored surveillance strategies. Full article

To address the issues of vibration in high-speed machining and the challenge of balancing motion smoothness and precision, this paper proposes a cascade control method based on a single-neuron adaptive PID. The method employs a dual closed-loop structure with a position loop and a speed loop, each regulated by a single-neuron adaptive PI controller. By dynamically adjusting the connection weights of the neurons online, real-time tuning of the proportional and integral parameters is achieved, enabling the system to adaptively regulate the control action. Simulation and experimental results demonstrate that the proposed controller ensures a 100% positioning accuracy across diverse motion scenarios with less than 0.05% relative error, enables effectively smooth motion, and effectively suppresses machine tool vibration caused by acceleration and deceleration processes. This significantly improves the system’s dynamic response and motion smoothness, providing an effective solution for high-speed and high-precision machining control. Full article

Since the number of existing steel-reinforced concrete buildings affected by carbonation-induced corrosion is steadily increasing, there is a high demand for durable repair methods. Chemical re-alkalization (CRA) represents one such approach, relying on the transport of alkaline pore solution from a repair mortar into carbonated concrete. With the introduction of clinker-reduced binder systems such as hybrid alkali-activated binders (HAABs), their suitability for CRA and governing material parameters require further clarification. In this study, material-related chemical and structural influences on CRA were investigated using an adapted form of Fick’s second law of diffusion, incorporating a time-dependent attenuation factor, β(t). The CRA progression was evaluated over 28 days, distinguishing between an initial suction phase and a subsequent diffusion phase. The results show that a high initial alkalinity of the mortar pore solution (pH > 14) significantly enhances re-alkalization during the suction phase, reflected by suction factors a > 1. In contrast, progression during the diffusion phase is primarily governed by the potassium concentration gradient at the mortar–concrete interface, while structural parameters such as capillary porosity show no systematic correlation with the deceleration factor b (−0.46 ≤ b ≤ −0.26). The findings indicate that, within the investigated range, mortar pore solution chemistry has a stronger influence on CRA than structural properties, providing guidance for the targeted design of alkaline repair mortars. Full article

Background/Objectives: Non-dilated left ventricular cardiomyopathy (NDLVC) is a recently defined clinical entity associated with increased risk of ventricular arrhythmias (VA) and sudden cardiac death (SCD), despite preserved LV geometry. The role and temporal variability of noninvasive electrocardiographic (ECG) risk markers in this population remain insufficiently characterized. To assess the temporal variability of ECG-derived risk markers in patients with NDLVC and explore their association with major adverse cardiac events, including heart failure (HF) and VA hospitalization. Methods: We prospectively studied 55 patients with NDLVC who underwent cardiac magnetic resonance imaging and serial 24 h Holter monitoring, signal-averaged ECG, and standard 12-lead ECG over a one-year period. Patients were followed up for 39.5 ± 8.6 months. Nine ECG-based risk markers were analyzed, including premature ventricular contraction (PVC) burden, non-sustained ventricular tachycardia (NSVT) occurrence, its maximum rate and maximum beats, mean QTc interval, standard deviation of NN intervals (SDNN), deceleration capacity (DC), heart rate turbulence onset and slope (TO/TS), T-wave alternans (TWA), and late potentials. Clinical outcomes were HF and VA hospitalization. Logistic regression was used to evaluate associations between changes in ECG parameters and outcomes. Results: A change (from positive to negative and vice versa) in at least one ECG parameter was detected in 67.3% of patients, with the highest variability observed in TWA (34.5%), NSVT (23.6%), and PVC burden (23.6%). Despite this variability, only SDNN was significantly associated with increased risk of VA hospitalization during follow-up (OR = 0.98, 95% CI: 0.97–0.99, p = 0.006). No ECG changes were associated with HF hospitalization. Conclusions: Patients with NDLVC exhibit substantial temporal variability in noninvasive ECG risk markers. While most changes do not correlate with clinical events, an inverse association was found between SDNN and VA risk. These findings support the ongoing evaluation and the necessity to identify more effective risk stratification markers in this subgroup of patients. Full article

Change-of-direction (COD) capacity is a key performance metric in football due to the high volume of COD actions occurring during match play. This study aimed to (i) evaluate the repeatability of the 5-0-5 test and (ii) examine the relationship between acceleration and deceleration profiles of the 5-0-5 test and in-season peak performance. Nineteen national-level Portuguese football players competing in the under-23 Portuguese National Championship were analysed. Repeatability analysis was conducted using intraclass correlation coefficients (ICC). Paired-samples t-tests and Pearson correlations (r) were employed to assess within-subject differences and associations between 5-0-5 measures (highest accelerations from a standing start [ACC_S], deceleration prior to the change in direction (DEC_COD), acceleration after decelerating and changing direction [ACC_COD]) and seasonal peak performances (ACC_max). The in-season peak values were determined from the average of the three maximal values that occurred either in training sessions or in matches. Normalized (relative to seasonal performance) parameters showed good repeatability (ICC = 0.76–0.85). The best ACC_COD and DEC_COD were not significantly different from ACC_max [ACC_COD] vs. ACC_max: (5.04 ± 0.39 m/s² vs. 5.36 ± 0.54 m/s²; p > 0.05) and DEC_max [DEC_COD] vs. DEC_max: (−6.47 ± 0.26 m/s² vs. −6.35 ± 0.61 m/s²; p > 0.05), respectively. The average and best 5-0-5 ACC_S performances showed significant, moderate correlations (r = 0.48; p = 0.040 and r = 0.50; p = 0.028, respectively) with the players’ peak in-season acceleration performance. Therefore, the best ACC_S and ACC_COD attempts can reflect values above 90% of ACC_max, while DEC_COD reflects values above 100% of DEC_max and may assist in monitoring and tailoring training for this capacity on an individual basis. Full article

Alfalfa is a high-quality forage crop whose viscoelastic properties strongly influence the performance of baling, pickup, and stacking operations. In this study, small alfalfa block specimens were tested using a universal testing machine to investigate stress relaxation and creep behaviors under different moisture contents (12%, 15%, 18%), densities (100, 150, 200 kg/m³), and maximum compressive stresses (8, 12, 16 kPa). Experimental data were fitted using viscoelastic models for parameter analysis. Results indicated that the relaxation response consisted of a rapid attenuation followed by a slow stabilization phase. The five-element Maxwell model achieved a higher fitting accuracy (coefficient of determination, R² > 0.997) than the three-element model. The creep process exhibited three stages, including instantaneous elastic deformation, decelerated creep, and steady-state deformation, and it was accurately represented by the five-element Kelvin model (R² > 0.998). Increasing moisture content reduced stiffness, while moderate moisture improved viscosity and shape retention. Higher density enhanced blocks compactness, stiffness, and damping characteristics, resulting in smaller deformation. The viscoelastic response to compressive stress showed moderate enhancement followed by attenuation under overload, with the best recovery and deformation resistance observed at 12 kPa. These findings elucidate the viscoelastic behavior of alfalfa blocks and provide theoretical support and engineering guidance for evaluating bale stability and optimizing pickup–clamping parameters. Full article

Planetary gear is the mainstream deceleration transmission device, and its derivative form of high contact ratio internal gear adopts the structure of full internal meshing. While improving the compactness and efficiency of the transmission, it is necessary to focus on its lubrication characteristics and churning power consumption. In this paper, based on the actual meshing state of high contact ratio internal gear, combined with its geometric parameters, motion speed, and pressure bearing state, the Computational Fluid Dynamics (CFD) model is used to analyze the oil distribution during gear motion. According to the oil state, the oil pressure and viscous force on the gear surface are extracted, the churning loss of the gear is calculated, and the influence of different parameters on the churning loss is analyzed. Finally, based on the influence of the oil churning parameters on the lubrication performance, the representative oil churning parameters are selected for the test. The test results are consistent with the results obtained by the simulation analysis, which provides data support for the study of the lubrication of high contact ratio internal gears. Full article

Copper (Cu) pollution poses environmental and health risks. Owing to its adaptability and potential for water purification, Nymphoides peltata (N. peltata) is being considered for use in the remediation of Cu pollution. However, the feasibility of using N. peltata for the remediation of Cu-polluted water bodies has not yet been assessed. Here, the physiological response of N. peltata to Cu stress was determined. N. peltata samples were exposed to varying Cu concentrations (0.2, 0.4, 0.6 and 0.8 mg∙L⁻¹), and the activities of glutamine synthetase (GS), nitrate reductase (NR), nitrite reductase (NiR), ribulose-1,5-diphosphate carboxylase (Rubisco), and glycolate oxidase (GO) were measured together with the concentrations of photosynthetic pigments. The results revealed that under Cu stress, NR and GS activities significantly decreased, while NiR activity significantly increased. Exposure to 0.2 mg∙L⁻¹ Cu promoted chlorophyll synthesis and enhanced Rubisco and GO activities; in contrast, exposure to Cu concentrations above 0.4 mg∙L⁻¹ significantly inhibited the aforementioned parameters. These findings indicate that Cu stress, regardless of concentration, significantly affects nitrogen metabolism in N. peltata by decelerating nitrate reduction and impairing the ammonification process. Meanwhile, only high Cu concentrations significantly affected photosynthesis. N. peltata can survive low Cu stress by regulating its photosynthetic enzymes. Therefore, N. peltata has potential for the ecological restoration of water bodies polluted with low Cu concentrations. Full article

Significant progress in autonomous vehicle (AV) development has been made over the years through advancements in artificial intelligence, sensor technology, and data processing; however, many challenges remain, particularly regarding road safety and the complexity of adapting these vehicles to certain traffic situations. As a result, many European countries are funding research projects and setting targets and strategic plans for autonomous mobility, while scientific research proposes establishing standards and design guidelines for adapting road infrastructure to new transportation trends. This review paper examines physical road infrastructure in the era of AVs and identifies potential modifications, considering the development of AVs during both the early and later stages of their introduction into mixed traffic flow. Accordingly, necessary road infrastructure adaptations and the main design parameters affecting road geometric design for AV operation are presented. The design parameters considered include stopping sight distance, vertical curve radii, straight sections, lanes, and others. Furthermore, potential changes in existing physical infrastructure are illustrated using the example of a deceleration lane. Whether it is new infrastructure or modifications to existing infrastructure, both are analyzed in terms of the proportion of AVs in the traffic flow. Full article

The persistent Hubble tension—marked by a notable disparity between early- and late-universe determinations of the Hubble constant $H_0$—poses a serious challenge to the standard cosmological framework. Closely linked to this is the $H_0-r_d$ tension, which stems from the fact that BAO-based estimates of $H_0$ are intrinsically dependent on the assumed value of the sound horizon at the drag epoch, $r_d$. In this study, we construct a scalar field dark energy model within the framework of a spatially flat Friedmann–Lemaitre–Robertson–Walker model to explore the dynamics of cosmic acceleration. To solve the field equations, we introduce a generalized extension of the standard Lambda Cold Dark Matter model that allows for deviations in the expansion history. Employing advanced Markov Chain Monte Carlo techniques, we constrain the model parameters using a comprehensive combination of observational data, including Baryon Acoustic Oscillations, Cosmic Chronometers, and Standard Candle datasets from Pantheon, Quasars, and Gamma-Ray Bursts (GRBs). Our analysis reveals a transition redshift from deceleration to acceleration at $z_{\mathrm{tr}}=0.69$ and a present-day deceleration parameter value of $q_0=-0.64$. The model supports a dynamical scalar field interpretation, with an equation of state parameter satisfying $-1<{\omega }_0^{\varphi }<0$, consistent with quintessence behavior, and signaling a deviation from the $\mathrm{\Lambda }$. While the model aligns closely with the Lambda Cold Dark Matter scenario at lower redshifts ($z\lesssim 0.65$), notable departures emerge at higher redshifts ($z\gtrsim 0.65$), offering a potential window into modified early-time cosmology. Furthermore, the evolution of key cosmographic quantities such as energy density ${\rho }^{\varphi }$, pressure $p^{\varphi }$, and the scalar field equation of state highlights the robustness of scalar field frameworks in describing dark energy phenomenology. Importantly, our results indicate a slightly higher value of the Hubble constant $H_0$ for specific data combinations, suggesting that the model may provide a partial resolution of the current $H_0$ tension. Full article

This paper presents an experimental study of the Automatic Emergency Braking (AEB) system, focusing on three essential testing phases: verifying the match between calculated and actual brake actuator operation time, validating the forecasted vs. real-time stabilized deceleration onset duration, and comparing the theoretically computed braking distance derived from mathematical models with its actual measurement. Standard instrumentation coupled with an original test procedure was utilized during the experiments. A full-scale experimental campaign was conducted on a specialized proving ground, thus substantiating the validity and robustness of the computational models used for assessing the AEB system parameters. The empirical outcomes confirmed that current-generation AEB systems offer dependable predictions regarding braking dynamics and exhibit prompt responsiveness to imminent collisions. However, it should be noted that variations in road conditions, driver behavior, and sensor precision may affect their performance. Consequently, additional efforts aimed at optimizing existing AEB solutions are required to minimize potential errors and enhance overall reliability. Finally, the significance of complying with design specifications and continuously upgrading AEB systems to meet evolving road safety standards is emphasized. Full article

Introduction: Manual therapists routinely evaluate changes in pain, movement, and function through clinical tests that support clinical reasoning. The Prone Hip Extension Test (PHET) is commonly used as a self-perturbation task to assess lumbopelvic control and hip motion patterns related to gait. Performing the PHET actively and passively may reveal how voluntary activation and passive structures influence joint kinematics and contribute to force production. This study aimed to compare active and passive PHET execution and investigate how initial (IP) and final hip positions (FP) correlate with lower-limb neuromuscular function. Methods: Seven healthy volunteers (24.3 ± 3.4 years; 173.1 ± 7.5 cm; 72.1 ± 9.5 kg) without musculoskeletal conditions participated. Hip kinematics were recorded using a 12-camera Qualisys Oqus system (200 Hz) with 22 reflective markers, processed in Qualisys Track Manager 2.13 and exported to Visual3D. Participants performed three PHET trials in both IP and FP, with mean an-gles considered for analysis. Knee isokinetic performance was assessed on a Biodex System 4 at 180°/s and 300°/s for flexion and extension. Results: Significant differences between active and passive PHET emerged in the FP for rotational movements bilaterally (p = 0.02) and in IP adduction/abduction for both hips (right p = 0.03; left p = 0.02). No side-to-side differences were observed. Passive FP of the right hip showed multiple significant correlations with isokinetic flexion and extension parameters at 180°/s and 300°/s, particularly with torque/body weight, acceleration and deceleration times, and agonist/antagonist ratios (ρ ranging from −0.86 to 0.90). Conclusions: Meaningful differences exist between active and passive PHET performance, especially in frontal-plane IP and rotational FP measures. Additionally, passive FP strongly correlates with several neuromuscular variables, suggesting that PHET kinematics may reflect lower-limb isokinetic function. Full article