Search Results (399)

This study presents a sensor-fused field investigation and simulation-based analysis of four horizontal and vertical traffic-calming devices—two raised speed tables, a speed hump, and a raised crosswalk—installed along a 5250-ft two-lane residential collector in Nashville, TN, USA. A dual-sensor architecture combining a Miovision Scout video-based vehicle counter and WAAS/EGNOS-augmented GPS probe-vehicle logging (5 m 3-D RMS horizontal accuracy, 1 Hz sampling) was used to reconstruct 30 quality-controlled free-flow vehicle trajectories and 12-h per-lane volume counts. A spatial kinematic transform (a = v·dv/dx) was applied to extract device-specific approach-deceleration and post-device recovery-acceleration rates, and a three-parameter log-logistic cumulative-distribution function was fitted to the field-observed desired-speed percentiles (root-mean-square error below 0.043 for both speed-table devices). The camera- and GPS-derived observations were used to calibrate and statistically validate a PTV VISSIM microsimulation replica of the corridor, achieving a mean-speed calibration error of 0.71% or better at every device, a GEH statistic below 1.5 at all four analysis turning movements, and independent travel-time validation errors of 5.7–12.1%, within the accepted 15% threshold. The validated model was then used to reconstruct device- and spacing-specific May–Keller macroscopic speed–density–flow relationships, calibrated against simulated capacities of 650–775 vehicles per hour per lane at 350-, 700-, and 1050-ft device spacing. Results show capacity reductions of 20–33% relative to free-flow conditions and yield kinematically derived maximum recommended spacings of 265–630 ft to maintain crossing speeds at or below 15 mph, depending on device geometry. The findings demonstrate a reproducible, low-cost sensor-fusion workflow for quantifying the safety–capacity trade-off of traffic-calming corridors and for informing the design of sensor-in-the-loop adaptive-calming infrastructure. Full article

Background: The Heart Rate Recovery Index (HRRI), derived from post-exercise heart rate recovery (HRR), reflects autonomic function and cardiovascular performance. Whether HRRI reflects early myocardial dysfunction and left atrial remodelling in heart failure with preserved ejection fraction (HFpEF) has not been previously examined. The H₂FPEF score, which integrates clinical and echocardiographic parameters, is used to assess the likelihood of HFpEF. This study investigates the relationship between HRRI, H₂FPEF score, and echocardiographic markers of longitudinal systolic function, including mitral annular plane systolic excursion (MAPSE), as well as left atrial volume index (LAVI), in patients with preserved left ventricular ejection fraction. Methods: A prospective observational study included 241 patients referred for cardiac exercise testing at the Institute of Cardiovascular Diseases Timisoara and the Clinical County Hospital of Sibiu. HRRI was calculated as the ratio of heart rate acceleration time (AT) to deceleration time (DT) during exercise testing. A comprehensive echocardiographic assessment was performed on all patients. Statistical analysis involved univariate testing and multivariable logistic regression with stepwise selection. Results: HRRI was significantly lower in HFpEF patients compared with those without heart failure (1.97 ± 0.66 vs. 2.73 ± 1.08, p < 0.01). HRRI correlated significantly with exercise performance, age, H₂FPEF score, and echocardiographic markers of diastolic and longitudinal systolic dysfunction. ROC analysis identified an HRRI cut-off value of 2.25 for HFpEF detection (AUC = 0.748), while HRRI remained significantly associated with HFpEF after adjustment for the covariates included in the model. The combined HRRI–H₂FPEF score improved diagnostic discrimination compared with the H₂FPEF score alone (AUC 0.897 vs. 0.858), achieving an overall classification accuracy of 82.2%. Conclusions: In our study, HRRI is significantly reduced in HFpEF and distinguishes patients with and without heart failure. It shows associations with echocardiographic markers of diastolic and longitudinal systolic dysfunction, exercise capacity, and H₂FPEF score. Full article

Reservoir landslides pose a persistent threat to the safe operation of hydropower projects, particularly where altered rock masses within water-level fluctuation zones undergo repeated wetting–drying and seepage-induced deterioration. This study investigates the mechanical behavior and long-term strength evolution of altered granite from the Guobu Slope near the Laxiwa Arch Dam in Qinghai, China. Rock masses with four alteration degrees, ranging from complete to slight alteration, were examined through an integrated experimental program involving torsional shear tests, hydro-mechanical coupled triaxial tests, large-scale direct shear and ring shear tests, Brazilian splitting tests, and long-term P-wave velocity monitoring. The results demonstrate that increasing water content progressively weakens the shear strength of altered granite, while elevated seepage pressure further reduces its strength and deformation resistance under hydro-mechanical coupling. Residual shear behavior also shows a clear dependence on water content, indicating that post-peak strength deterioration should be considered in slope stability assessment. Long-term P-wave monitoring further reveals that mechanical degradation is more pronounced during the early stage and gradually approaches a relatively stable state, suggesting a site-specific decelerating deterioration process rather than unlimited strength loss. Based on the experimental results, empirical relationships between shear-strength parameters and water content are established, and long-term lower-bound strength parameters are proposed for altered granite with different degrees of alteration. These findings provide experimental support for understanding the hydro-mechanical deterioration and long-term deformation behavior of reservoir-bank altered rock masses and offer a basis for parameter selection and stability assessment when combined with rock-mass reduction, field calibration, and sensitivity analysis. Full article

We investigate interacting Barrow holographic dark energy (BHDE) with the Hubble horizon as the infrared cutoff in a fractal cosmological background. The fractal measure modifies the Friedmann sector and leads to the nonstandard closure relation ${\mathsf{\Omega }}_{\mathrm{dm}}+{\mathsf{\Omega }}_{\mathrm{de}}=1+\gamma$. Using Planck-inspired present-day normalization ${\mathsf{\Omega }}_{\mathrm{de}0}=0.6847$ and the benchmark parameters $(\Delta ,\omega ,\beta )=(0.8,0.263,0.123)$, we study four linear and nonlinear dark-sector interactions over $-0.99\le z\le 3$. The benchmark solutions remain within the physical background domain throughout this interval: the density fractions are non-negative, the relevant denominators remain positive, and the nonlinear $Q_3$ and $Q_4$ terms remain real. All four prescriptions exhibit a transition from decelerated to accelerated expansion. The non-interacting limit gives $z_t\simeq 0.86$, whereas for $\xi =0.12$ the transition redshifts are approximately $2.02$, $1.97$, $1.26$, and $1.87$ for $Q_1$, $Q_2$, $Q_3$, and $Q_4$, respectively; in particular, the $Q_4$ solution recovers a finite transition within the plotted redshift range. A stronger positive coupling generally shifts acceleration onset to a higher redshift, with the strongest response for $Q_1$ and the weakest for $Q_3$. The statefinder quantities $S_3^{\left(1\right)}$, $S_3^{\left(2\right)}$, and the s–r trajectories distinguish the interaction structures through their finite-redshift evolution and present-day values. A fixed-background SN Ia comparison using 1046 selected Pantheon supernovae, diagonal FITRES uncertainties, and an analytically profiled additive nuisance parameter gives the lowest information criteria for flat $\mathsf{\Lambda }$CDM. Among the BHDE benchmarks that interact, $Q_4$ is the closest case, with $\Delta \mathrm{AIC}=\Delta \mathrm{BIC}\simeq 1.21$. This comparison is not intended as a global posterior constraint on the model parameters. Full article

Wave propagation along acoustic black hole waveguides (ABH) consisting of arrays of functionally graded perforated rings (FGPR) is investigated by developing their linearized electro-acoustic analog models. These models simulate the interactions between the different components of the ABH/FGPR as influenced by the design parameters of the perforated rings and coupled acoustic cavities. The developed electric analogs consist of arrays of resistors simulating the flow resistance through the perforations, inductances to quantify the inertia of the gas moving inside these perforations, and capacitances to describe the storage behavior of the cavities between neighboring rings. The dynamic interactions between these electric components are described by a state-space model in terms of the incoming and outgoing flow velocities as well as the pressures before and after each FGPR. In this manner, it is possible to determine the spatial distributions of the flow velocities and pressures along the ABH which are necessary to demonstrate the effectiveness of the proposed ABH/FGPR in generating the ABH effect by monotonically decelerating the flow along the waveguide and bringing it to a complete stop. The predictions of the developed electro-acoustic analog models are validated against the predictions of the classical “Transfer Matrix Method (TMM)” and experimental results established by Petrover and Baz (2025). Furthermore, these predictions are also validated against the predictions of a developed MATLAB SimScape Model of the electro-acoustic analogs. The comparisons between the predicted and measured results show close agreements and validate the accuracy of the developed electro-acoustic analog models. Full article

Stable drainage of coalbed methane wells is essential for reducing reservoir pressure and promoting methane desorption. However, coal fines carried by produced water tend to accumulate and deposit within the standing valves of drainage pumps. To address this common problem, this study investigates the transport characteristics of coal fines within the standing valve during the liquid-dominated water-pumping stage of the plunger upstroke, with the standing valve fully open. Theoretical calculations, numerical simulations, and settling experiments were conducted for three coal fines size fractions of 60–100, 100–200, and 200–400 mesh to validate the model’s predictive capability for coal fines motion. The results show that the RNG k–ε model has the lowest mean absolute relative error, at 14.50%. A solid–liquid two-phase flow model was employed to comparatively analyze five valve seat cone angles ranging from 105° to 165° and representative inlet velocities of 0.1–0.4 m/s. The results indicate that the mixture within the standing valve accelerates markedly while passing through the narrow clearance between the valve ball and the valve seat and then decelerates in the region above the valve ball. The region above the valve ball and the valve seat transition region are the primary locations of instantaneous coal fines enrichment. Increasing the inlet velocity generally enhances coal fines transport capacity and reduces the local maximum solid-phase volume fraction. Larger coal fines particles exhibit more pronounced inertial deviation and a higher degree of local enrichment, whereas smaller particles show stronger flow-following behavior and a more dispersed spatial distribution. The results further indicate that, within the investigated structural range, the 150° valve seat cone angle provides the best overall balance between coal fines transport capacity and hydraulic resistance. Ultimately, the findings provide a theoretical foundation and methodological reference for understanding the anti-clogging mechanisms of CBM pump standing valves, optimizing structural parameters, and guiding the blockage-resistant design of downhole flow components. Full article

Background: Parkinson’s disease (PD) diagnosis is often delayed until signature motor symptoms manifest, at which point profound dopaminergic neuron loss has already occurred, necessitating advanced motor diagnostic biomarkers. Quantitative gait analysis is a promising tool, but phase-specific kinematic parameters remain underexplored. This study aims to identify novel, stage-divided Timed Up and Go (TUG) biomarkers not only to differentiate healthy controls (HCs) from patients with PD but also to objectively monitor and track disease progression across advancing severity stages, which are further validated against conventional clinical motor scales. Methods: A total of 81 participants (48 PD, 33 HCs) performed a 3 m TUG test using MotionCore (JEIOS Inc., Busan, Republic of Korea). The test was subdivided into three movement phases (Stage 1, sit-to-walk; Stage 2, turning; Stage 3, walk-to-sit). Results: PD patients exhibited significantly prolonged durations and altered turning metrics compared to HCs. Turning parameters including turning radius (ETR), area (EMA), and turning stability (FN) demonstrated strong correlations with disease severity and clinical scales. Notably, stage-specific analyses revealed that step counts, time, and speed metrics across Stages 1, 2, and 3 effectively differentiated disease severity, with transitional decelerating and seating metrics in Stage 3 showing the most pronounced clinical correlations. Discussion: This study confirms that the TUG test systematically deteriorates with increasing PD severity. The robust correlations with clinical scales (UPDRS, FOG-Q, BBS) validate TUG metrics as objective measures of motor and balance impairments. Utilizing novel, staging-specific indices significantly enhances the TUG test’s clinical utility for supporting diagnosis, accurate staging, and monitoring disease progression. Although the overall group comparisons demonstrated statistical significance, a data overlap remains between mild PD and HCs, underscoring the need for large-scale longitudinal studies to validate these metrics for early detection. Full article

To investigate the influence of aggregate fractal gradation on the time-dependent deformation of cemented coal gangue backfill, four groups of specimens with different aggregate fractal dimensions were prepared based on mass fractal theory. Multi-stage loading creep tests were conducted to examine the effects of aggregate fractal dimension on creep strain, steady-state creep rate, and long-term strength. An improved fractional-order Burgers creep model incorporating a fractional Abel dashpot was then established to describe the creep response and to further interpret the relationship between aggregate gradation and model parameters. The results show that the creep deformation of cemented coal gangue backfill increased with increasing stress level and exhibited instantaneous deformation, decelerating creep, steady-state creep, and accelerating creep stages. With increasing aggregate fractal dimension, the creep deformation, steady-state creep rate, and damage accumulation first decreased and then increased. Among the tested aggregate fractal gradations, the specimen with D = 2.41 exhibited the best creep resistance, with a long-term strength of 8.83 MPa, approximately 33.40% higher than that of the specimen with D = 2.20. This behavior may be attributed to a more favorable coarse–fine particle proportion, which improves particle filling and skeleton continuity under the present material system. The comparison between experimental and fitted results indicates that the improved fractional-order Burgers model can effectively reproduce the creep process of cemented coal gangue backfill, with coefficients of determination greater than 0.97 for all tested specimens. These findings provide a useful reference for aggregate gradation optimization and creep-resistance evaluation of cemented coal gangue backfill under laboratory multi-stage loading conditions. Full article

With the increasing complexity of electrical and electronic (E/E) components in modern powertrains, functional safety requires more systematic assessment methods. This paper presents a simulation-based approach for automated Hazard Analysis and Risk Assessment (HARA) of battery electric vehicles in accordance with ISO 26262. The method combines operational-situation parameters, including vehicle speed, road surface, vehicle gap, and road inclination, to define a structured set of hazardous events. Severity, Exposure, and Controllability are evaluated using rule-based criteria, including a dedicated Controllability rule set for longitudinal motion hazards. Quantitative erroneous acceleration and deceleration thresholds associated with different ASILs are derived using a bisection search algorithm, enabling quantifiable and testable safety goals. Comparison with manual HARA reveals systematic biases: low speed does not necessarily imply improved Controllability due to shorter vehicle gaps, while Severity may be underestimated at low speeds because of high instantaneous electric-machine torque. The maximum ASIL is often identified similarly by simulation and experts, whereas lower-ASIL hazardous events may lack consistency and coverage in manual HARA. As a practical application, the approach can be integrated into existing automotive safety workflows as a HARA support tool, improving the consistency of lower-ASIL events while allowing engineers to focus on maximum ASIL cases. Full article

This study aims to clarify the mesoscopic damage evolution mechanisms of concrete subjected to rigid projectile penetration and provide support for the optimal design of high-performance protective structures. Based on the ABAQUS/Explicit finite element framework, a three-phase mesoscopic numerical model of concrete considering aggregate, mortar matrix, and interfacial transition zone (ITZ) is constructed. By combining the random convex polygon algorithm with the background mesh mapping technique, the intrinsic geometric features of stochastic materials such as crushed stone and pebble are accurately characterized. The effects of aggregate geometric characteristics, volume fraction, and projectile motion/geometry parameters (velocity, length–diameter ratio, curvature radius of the warhead CRH) on the damage evolution of the target, penetration depth, and velocity attenuation law are systematically investigated. The results reveal that increased aggregate angularity substantially enlarges both tensile and compressive damage zones and promotes crack bifurcation, which collectively enhances kinetic energy dissipation, reduces penetration depth, and accelerates projectile deceleration. Increasing the aggregate volume fraction can significantly enhance the anti-penetration resistance of the target. A high proportion of aggregate grains effectively enhances the structural toughness by blocking the crack propagation path. Penetration velocity, length–diameter ratio, and CRH are the core elements determining the penetration efficiency, and the increase in their values will lead to a significant increase in penetration depth and induce a change in the damage mode from local failure to large-scale cracking. The mesoscopic model and related conclusions established in this study can provide a theoretical foundation and numerical benchmark for the impact resistance design, optimization, and damage assessment of high-strength concrete protective structures. Full article

Unsteady laminar pipe flows, prevalent in oscillating liquid columns, physiological pulsatile systems, and hydraulic transients, exhibit instantaneous velocity distributions that deviate significantly from the classical Hagen–Poiseuille parabolic profile. This deviation is governed by the interaction of inertial effects, viscous diffusion, phase lags, and localized flow reversal. Despite extensive documentation of these phenomena, a systematic framework for quantifying such morphological deviations remains largely undeveloped. This study proposes a suite of physically grounded indicators to quantify velocity profile distortion. These metrics characterize complementary aspects of non-Poiseuillean behavior, specifically: centerline curvature variation, profile flattening, energetic divergence, radial peak migration, reverse-flow fraction, and the emergence of inflection points. The methodology employs an analytical reconstruction of the local velocity field through a generalized Fourier–Bessel solution of the linearized Navier–Stokes equations, calibrated against experimental free-surface motion in a vertical U-tube undergoing damped oscillations. The application of these indicators demonstrates consistent correlations between geometric, energetic, and topological features during acceleration, deceleration, and flow-reversal phases. The findings indicate that no single parameter adequately captures the complexity of unsteady fields, but the integrated framework provides a robust classification of instantaneous flow regimes. This approach delineates the limitations of Poiseuille-based assumptions and establishes a quantitative foundation for advanced unsteady friction models. Full article

Pulse wave propagation through blood vessels is affected by many biophysical parameters that change with aging. The aim of this study was to investigate both theoretically and experimentally how the pulse wave velocity changes in the vertical position and to introduce a new parameter in biophysics: pulse wave acceleration (PWA). Using a biophysical model of the cardiovascular system, placed in horizontal and vertical positions, pressure waveforms were measured along the arterial tree at several sites at different diastolic pressures and pump frequencies. Blood flow waveforms on the carotid and femoral arteries in the supine and standing positions were measured on the subjects. The results showed that the pulse pressure wave accelerates in the direction of gravity and decelerates in the opposite direction both in the model and in humans. A new biophysical parameter, PWA, was defined, and the experimental results are in agreement with the mathematical model. Due to the acceleration of the pulse wave, the reflected wave in the standing position arrives earlier in systole and contributes to the increase in pressure. This emerging biophysical parameter may contribute to a better understanding of the phenomenon of wave propagation of blood through blood vessels. Full article

Background/Objectives: The objective of this study was to evaluate macular perfusion changes after intracameral injection (ICI) of cefuroxime at the end of phacoemulsification. Methods: Patients who underwent routine phacoemulsification were enrolled. Subjects in the case group had ICI 1 mg/0.1 mL cefuroxime at the end of surgery. Using optical coherence tomography angiography (OCT-A), macular perfusions were assessed at T0 (before surgery), T1, T10, T30, and T90 (days after surgery). Perfusion parameters were calculated in the superficial capillary plexus (SCP) and the deep capillary plexus (DCP). Independent t-tests were used to compare the changes from baseline in each parameter between groups. Results: A total of 33 eyes in the case group and 27 eyes in the control group were enrolled. After surgery, the case group showed a less pronounced reduction in the foveal avascular zone (FAZ) in the DCP at T10 (−0.06 ± 0.23 vs. −0.18 ± 0.18 mm², p = 0.041) and T30 (−0.04 ± 0.20 vs. −0.16 ± 0.24 mm², p = 0.050). At T90, there was no statistically significant difference in the FAZ change in the DCP between the groups. The postoperative changes in the vessel density, skeleton density, and acircularity index of the FAZ in the SCP and DCP, central retinal thickness, and best-corrected visual acuity were similar between the groups in all 3 months. Conclusions: Our findings indicate that intraoperative ICI low-dose cefuroxime is associated with a temporary deceleration in FAZ reduction in the DCP during the first postoperative month. From a personalized medicine perspective, these layer-specific microanatomic variations suggest that, while prophylactic cefuroxime is globally safe—demonstrating no evidence of inducing capillary dropout, aggravating macular thickening, or compromising visual outcomes within this cohort—preoperative and postoperative OCT-A monitoring can serve as an individualized screening framework to track subclinical perfusion dynamics, especially in patients with compromised retinal baselines. Full article

Train brake systems are characterized by strong friction and open-system features during the service process. Low environmental temperatures significantly affect the contact interface and the attrition characteristics of the braking frictional couple, thus intensifying friction-induced vibration and threatening operational safety. To elucidate the impact of environmental temperature on the frictional vibration characteristics of train brake systems, braking deceleration tests under different environmental temperatures were first conducted to obtain the evolution of vibration, noise, and friction coefficient with environmental temperature and brake disc rotational speed. Then, the Stribeck friction parameters under different environmental temperatures were identified using a genetic algorithm. On this basis, a brake system dynamic model was developed, incorporating disc–pad friction, wheel–rail adhesion, and the relative torsion between the brake disc and the wheelset, enabling accurate examination of the vibrational behaviour arising from friction under different environmental temperatures. And the dynamic relationship among environmental temperature, interface friction parameters, and vibration characteristics of the brake system during braking deceleration was elucidated. The findings indicate that as the environmental temperature decreases, the dynamic friction coefficient increases during the relatively high-speed braking phase, intensifying high-frequency unstable vibrations of the braking assembly. During the relatively low-speed braking phase, the friction coefficient exhibits an obvious negative-slope relationship with vehicle speed that means the friction coefficient increases as the speed decreases, and this negative slope effect is enhanced under low-temperature conditions. Consequently, it triggers intense stick–slip motion at the disc–pad interface and even severe vibrations of various components in the brake system, leading to a sudden increase in vibration intensity in the relatively low-speed range. Full article

The reformulation of cookies using alternative flours and structured lipid systems represents a promising strategy for improving their nutritional profile. The present study characterized the dough properties, baking behavior, compositional attributes, and 48-day storage physicochemical and textural stability of cookie formulations combining mesquite or wheat flour with varying proportions of shortening and monoglyceride-based oleogel. A multifaceted modeling and temporal analysis approach was employed to assess the impact of flour type, fat blend, and storage duration on critical physicochemical variables. The findings of the study indicated that the type of flour was the predominant factor influencing moisture retention, ash content, and the rate of bake loss. In contrast, the fat blend was found to regulate oil migration and dough mechanical parameters. Oleogel-rich systems demonstrated superior stability over time, as evidenced by a diminished color change and a decelerated textural hardening process in comparison to conventional shortening controls. Concurrently, these systems maintained water activity levels below the established microbiological safety thresholds. Sensory analysis demonstrated that oleogels effectively replicated the mouthfeel and acceptability of conventional fats, exhibiting comparable hardness and crunchiness to traditional formulations. However, mesquite flour-rich formulations exhibited higher bitterness and lower adhesiveness. These findings demonstrate that oleogel incorporation provides a viable strategy for mitigating textural staling and improving lipid profiles of cookies. Full article