Search Results (286)

The new LOAC2 optical aerosol counter is designed to detect liquid and solid particulates across 19 to 30 size classes within the 0.15–90 µm size range, and to provide their main typology. The instrument can be used at ground level and on all kinds of balloons, including weather balloons, up to an altitude of about 35 km. The measurements are based on principles established for the previous version of LOAC, now incorporating improved electronics and detection geometry. Counting is performed at small scattering angles in the diffraction domain, making it insensitive to the refractive indices and the porosity of the particles, thus allowing a direct relationship between scattered intensity and aerosol size. Typology identification is now performed at three additional scattering angles, where the scattered flux is highly sensitive to the refractive index of the different aerosol families present in the atmosphere. The calibration was conducted using calibrated spherical and irregular grains, as well as different types of solid particles. Several intercomparison sessions with other counters and with reference mass-concentration air quality monitoring stations were carried out indoors, in an atmospheric simulation chamber, and in outdoor ambient air. The agreement between LOAC2 and the other instruments is good, confirming the ability of LOAC2 to be used for scientific studies and for monitoring atmospheric aerosols. Full article

In this work, it is demonstrated that the tilt angle of an etalon can be determined by analyzing some features of an intensity distribution pattern (interferogram) with machine learning algorithms. These features present a strong nonlinear relationship with the etalon tilt angle, showing several discontinuities and ambiguities within a 20° range. Here, a regression based on an ensemble of artificial neural networks was implemented to correctly estimate the tilt angle. By using this ensemble, the tilt angle was estimated with a mean absolute error of 0.028° and root squared error of 0.047°, for a measurement range between —10.013° and 10.013°. Finally, it is shown that in this way both magnitude and direction of the tilt angle can be determined from just an image and additionally that to perform this task a simple optical setup was required, reducing its overall cost. Full article

The release kinetics of functional compounds from active packaging systems plays a crucial role in determining their efficiency, as it directly affects the availability of the incorporated agents and the extension of the product’s shelf life. Therefore, controlled release behaviour is essential for optimizing the functionality of such materials. In the present study, corona treatment was used as a surface modification technique to tailor the release behaviour of polyphenols—curcumin, quercetin, and rutin—from polylactic acid (PLA) films. Polyphenol release was performed in a model medium (3% acetic acid), and the experimental data were fitted using commonly applied kinetic models to elucidate the release mechanism. The results indicate that corona-treated films exhibit significantly accelerated release kinetics and higher cumulative release compared to untreated samples. To interpret the observed behaviour, different surface characterization techniques were applied. Scanning electron microscopy (SEM) revealed only minor changes in the morphology of the uncharged and charged samples, which are unlikely to account for the observed differences in the release behaviour. Fourier transform infrared spectroscopy (FT-IR) confirmed that corona treatment has led to formation of new peaks in PLA spectrum and change in the shape and intensity in PLA–polyphenol loaded films. Contact angle measurements demonstrated increased surface wettability after treatment. These changes are associated with enhanced polymer–medium interactions and improved mobility of the incorporated polyphenols, leading to accelerated release. These findings demonstrate that corona treatment is an effective strategy for tuning the release kinetics of PLA-based systems. The developed materials show strong potential for use in active packaging applications, where controlled release of antioxidant compounds is essential for extending product shelf life. Full article

Background/Objectives: Gymnastic exercises exert positive effects on chronic neck pain. Growing evidence suggests that combining cervical spine exercises with temporomandibular joint (TMJ) relax pads may enhance outcomes on pain, discomfort, and functional limitations. To evaluate the additive effect of silicone TMJ relax pads worn in the molar region during cervical spine exercises on reducing neck pain and selected mobility outcomes. Methods: In this study, 52 sedentary middle-aged adults working on video display unit (VDU) workstations were randomly assigned to two groups. Both groups performed a specific cervical spine exercise program (3 × 3 min/day) for three months. One group used bilateral TMJ relax pads during exercise (EX-RP) while the control group applied the identical exercises without pads (EX). Neck pain intensity was assessed using a one-week pain protocol prior to and after a 12-week intervention. Functional assessments included cervical/thoracic and shoulder mobility tests, and thoracic kyphosis angle measurement. An intention-to-treat analysis with multiple imputations was performed. Results: Data from 47 participants (EX-RP: n = 25; EX: n = 22) were analyzed. Neck pain decreased in both groups, with a significantly greater reduction in the EX-RP compared to the EX group (p = 0.046). Neck Disability Index (NDI) scores improved in both groups (p < 0.001), with no significant difference between groups (p = 0.514). EX-RP showed greater improvements in cervical extension (p = 0.044) and trunk rotation (p = 0.019); however, the results for other mobility outcomes were inconsistent. Conclusions: Adding TMJ relax pads to cervical exercises (alone) favorably affects the pain intensity and might enhance mobility outcomes in individuals with chronic neck pain. TMJ relax pads appear to be a feasible and low-threshold adjunct to exercise-based interventions. Full article

To address the nonlinear orbit determination problem under multi-satellite cooperative observation, this paper proposes an orbit determination method integrating a plane-constrained observation model with adaptive robust filtering. Based on angular measurements from multiple observation nodes, a linearized observation model is constructed using spatial geometric constraints. The Maximum Correntropy Criterion is then introduced to adaptively weight each measurement component, and a hybrid kernel function is employed to suppress the effects of non-Gaussian noise and outliers. Meanwhile, an adaptive factor based on the covariance matching principle is designed to adjust the process noise intensity online, thereby improving the robustness of the Cubature Kalman Filter in state prediction and update. Simulation results under severe non-Gaussian noise show that the proposed adaptive robust cubature Kalman filter (ARCKF) reduces the position RMSE from 95.3 m for CKF to 30.8 m, corresponding to an improvement of approximately 67.7%, while increasing the computation time from 6.52 s to 7.35 s. These results indicate that the proposed method can achieve improved accuracy and robustness under uncertain measurement statistics and dynamic disturbances, making it suitable for space-based angles-only orbit determination, although further computational optimization is still required for onboard applications. Full article

Loading fluctuations and fatigue-related structural demand under turbulent wind conditions are important factors that limit the reliability of small wind turbines. This study investigates the separate effects of turbulence intensity and pitch angle on a 5 kW distributed variable-pitch wind turbine prototype using an OpenFAST-based aeroelastic model validated against field measurements. Under the adopted simulation setup and selected operating conditions, increasing turbulence intensity from 5% to 20% leads to a pronounced increase in the extreme blade-root flapwise bending moment and a substantial reduction in the estimated comparative fatigue life. The analysis also reveals a clear trade-off between aerodynamic efficiency and structural durability: among the tested pitch settings, the 6° case yields the highest power output, but also exhibits the largest load fluctuations and the shortest estimated comparative fatigue life. Adjusting the pitch angle to 0° or 12°, while reducing power to some extent, alleviates fatigue-related structural demand and increases the estimated comparative fatigue life. Overall, the results provide a validated prototype-level comparative assessment of how turbulence intensity and pitch angle influence aerodynamic performance, structural response, and fatigue-related demand in the studied turbine. Because the present work focuses on one prototype and does not include cross-turbine comparison or a full stochastic convergence study, the reported quantitative results should not be interpreted as directly generalizable to other turbine configurations. These findings may nevertheless provide a useful basis for future studies on load-aware pitch regulation under turbulent inflow. Full article

This study aims to establish a quantitative relationship between the color parameters and mechanical properties of thermo-oxidatively aged epoxy resin, with the goal of exploring a low-cost, rapid method for mechanical performance assessment based on color measurement. Epoxy resin specimens were subjected to high-temperature aging for varying durations, after which multiple color parameters were measured using a portable colorimeter. The variations in these parameters with aging duration and intensity were systematically characterized. The results indicate that during thermo-oxidative aging, strength exhibits a monotonic correlation with certain color parameters, such as lightness and hue angle. Based on this finding, an empirical model was developed to estimate strength from color parameter values. A comparison between estimated and experimental results confirms the feasibility and potential of this approach. To make the validation more convincing, it utilized not only the data from this experiment but also data from the literature. This work provides a theoretical basis and a practical technical pathway for utilizing portable colorimeter to rapidly and non-destructively assess the aging extent and mechanical performance of polymeric engineering structures. Full article

Background: Chronic low back pain (CLBP) and depression often co-occur. This study compared a fascia-focused physiotherapeutic program with a conventional physiotherapeutic and relaxation-based program in psychosomatic inpatients with CLBP and comorbid depression. Methods: In this exploratory quasi-randomized study, 41 inpatients were allocated to a fascia-focused intervention group (n = 23) or a conventional active control group (n = 18). Over six weeks, the intervention group received Bowen therapy and fascia circuit training, whereas the control group received progressive muscle relaxation and strength circuit training. Outcomes were assessed at baseline and after rehabilitation. NRS pain intensity and BDI-II depressive symptom severity were the main clinically relevant outcomes; spinal function, tissue stiffness, pressure pain threshold, and craniovertebral angle were secondary or exploratory outcomes. Results: Both groups improved over time in pain intensity and depressive symptom severity. NRS scores decreased by 3.21 ± 2.61 points in the fascia-focused group and by 2.17 ± 2.34 points in the control group; BDI-II scores decreased by 9.30 ± 13.42 and 7.22 ± 8.57 points, respectively. Repeated-measures ANOVA confirmed significant time effects for NRS and BDI-II, with no significant group differences or time × group interactions. Significant time effects were also observed for thoracic tissue stiffness, lumbar and pelvic posture, thoracic and lumbar mobility, and pelvic stability. Conclusions: Fascia-focused and conventional physiotherapy showed similar observed effects in this exploratory quasi-randomized study. The absence of significant between-group differences should be interpreted cautiously because the study was not designed or powered to establish formal equivalence. Full article

To support low-cost, non-destructive crop growth monitoring, this study systematically compared different vegetation indices, voxel sizes, and camera angles using a point cloud voxelization approach combined with a vegetation index weighted canopy volume index (CVM_VI) to assess aboveground biomass (AGB) in winter oilseed rape (Brassica napus L.). Field experiments were conducted from 2021 to 2024 at the Yangma Experimental Base of the Chengdu Academy of Agricultural and Forestry Sciences. Red, green, blue (RGB) imagery of oilseed rape was acquired using an unmanned aerial vehicle (UAV) during the following five key growth stages: seedling, bolting, flowering, podding, and maturity. Collected images were processed to generate point clouds, which were subsequently voxelized at four resolutions (0.03, 0.05, 0.07, and 0.1 m). CVM_VI was constructed by integrating vegetation indices (VIs) derived from the RGB data and the voxelized canopy structural information. Regression models were established between the CVM_VI values and field-measured AGB to estimate biomass. Model performance was evaluated using the coefficient of determination (R²), root mean square error (RMSE), and relative error (RE). There were strong correlations (r > 0.80) between the estimated and measured AGB across all voxelization treatments throughout the growth period. Among the 20 VIs tested, regression methods based on the blue green ratio index (BGI), color intensity index, blue red ratio index, vegetative index, and green red ratio index consistently showed superior estimation performance across three consecutive years, demonstrating their good applicability for estimating AGB in oilseed rape under varying agronomic conditions (different varieties, densities, and sowing dates). The cubic regression model CVM_BGI performed best under a 45° UAV camera angle, with the highest R² and lowest RMSE and RE (2021–2022: R² = 0.864, RMSE = 2414.18 kg/ha, RE = 14.8%; 2022–2023: R² = 0.754, RMSE = 2550.53 kg/ha, RE = 14.9%; 2023–2024: R² = 0.863, RMSE = 1953.61 kg/ha, RE = 22.9%). Since the estimation performance showed negligible differences among voxel sizes, and the 0.1–m voxel offered the smallest data volume and shortest analysis time, the CVM_BGI model with a 0.1–m voxel was selected as the preferred approach, providing a practical balance between estimation performance and processing demand. These findings highlight the application potential of point cloud voxelization technology for crop biomass estimation. This study proposes a novel, non-destructive, and efficient framework for estimating field crop AGB using low-cost UAV RGB imagery, facilitating the wider adoption of UAV technology in practical agricultural production. Full article

Background: Work-related musculoskeletal disorders (WMSDs) are prevalent among orthopaedic surgeons as a result of prolonged exposure to non-neutral postures and forceful manual tasks during surgery. Although working height is a key determinant of trunk and upper-limb posture, the systematic evaluation of ergonomic working-height recommendations in orthopaedic surgery remains limited. Methods: A simulated left total knee arthroplasty (TKA) was divided into twelve critical surgical steps and analysed across four commonly used surgeon positions (A–D). Two conditions were compared: uncorrected working height (N) and working height corrected according to Canadian Centre for Occupational Health and Safety (CCOHS) recommendations (C). Joint angles were measured from standardized photographs using Kinovea software, and postural load was quantified with the Rapid Entire Body Assessment (REBA) method. Two trained evaluators conducted three independent assessments, yielding 288 REBA scores. Results: Mean REBA scores decreased across all surgeon positions following ergonomic correction, with statistically significant reductions observed in positions A, B, and D. When pooled across all position–step combinations (n = 48), the mean reduction was 0.92 REBA points (95% CI 0.50–1.33; p < 0.001). Notably, 27 of the 48 position–step comparisons exceeded the minimal detectable change threshold. The largest reductions occurred during force-intensive surgical steps, including bone cutting, drilling, and implant impaction. Conclusions: Adjusting working height in accordance with CCOHS ergonomic recommendations reduces surgeons’ postural load during TKA. These findings support the integration of evidence-based ergonomic adjustments into routine orthopaedic surgical practice. Full article

Lasers are a key enabling technology across numerous engineering and scientific fields, especially in high-energy laser systems for defense, materials processing, and fusion research, where precise characterization of high-power, large-divergence-angle laser spots is critical. However, the inherent properties of high-power, large-divergence-angle lasers—such as large spot area and strong intensity contrast—pose real obstacles to existing methods, which often suffer from low accuracy and inefficiency. In this paper, a flat-field correction technique was proposed for the CCD to reduce the distortions produced by the non-uniform response of the sensor in spot measurements. Then, a spot recognition algorithm based on support vector machines was developed, which can effectively and accurately locate and identify laser spots with limited training samples and computational resources, achieving a classification accuracy of over 98.11%. Additionally, an efficient correction approach is proposed to assess the spot intensity and shape with high accuracy even at large tilt angles. Experimental results show that this proposed approach can measure the high-power laser spot with a large divergence angle precisely and efficiently, and improves both the measurement precision and operational efficiency remarkably. Full article

To address the challenge of surrounding rock instability in deep-buried tunnels crossing fractured fault zones, this study focuses on the Xigu Tunnel of the Lanzhou–Hezuo Railway. A combination of laboratory triaxial tests, an optimized multi-source advanced geological prediction workflow, and a site-specific parameter-weakened Mohr–Coulomb numerical simulation is employed to systematically reveal the physical–mechanical properties, spatial distribution, and deformation response of fractured rock masses under excavation-induced disturbance. The triaxial test results show that the average peak strength of the surrounding rock reaches 149.04 MPa; however, significant variability is observed among samples, and the failure mode exhibits a typical brittle–shear composite feature. The measured cohesion and internal friction angle are 20.57 MPa and 49.91°, respectively, indicating high intrinsic strength of individual rock blocks. Nevertheless, due to the presence of densely developed joints and crushed structures, the overall mass is loose and highly sensitive to dynamic disturbances such as blasting and excavation, revealing a unique mechanical paradox of high-strength rock blocks with low overall rock mass stability in deep-buried fractured zones. Joint TSP (Tunnel Seismic Prediction Ahead) and ground-penetrating radar (GPR) prediction reveals decreased P-wave velocity, increased Poisson’s ratio, and intensive seismic reflection interfaces; a quantitative index system for identifying the boundaries of narrow deep-buried fractured zones is proposed based on these geophysical characteristics. Combined with geological face mapping, these results confirm the existence of a highly fractured zone approximately 130 m in width, characterized by well-developed joints, heterogeneous mechanical properties, and localized risks of blockfall and groundwater ingress. The developed numerical model, with parameters weakened based on triaxial test and geological prediction data, effectively reproduces the deformation law of the fractured zone, and the simulation results agree well with field monitoring data, with peak displacement concentrated at section DK4 + 595, thus accurately identifying the center of the fractured belt as a key engineering validation result of the integrated technical framework. During construction, based on the identified spatial characteristics of the fractured zone and the proposed targeted support insight, enhanced dynamic monitoring and targeted support measures at the fractured zone center are required to ensure structural safety and long-term stability of the tunnel. This study develops an integrated engineering-oriented technical framework for deep-buried tunnels crossing narrow fractured zones, and provides novel mechanical insights and quantitative identification indices for such complex geological engineering scenarios. Full article

Efficient plant protection requires precise monitoring of spray droplets, yet current in situ methods for measuring in-flight droplet flow are limited. This study proposed a laser imaging-based method to quantify spray intensity without physical contact or tracers. An optimal imaging angle was determined via simulation by maximizing the linearity between the received optical feature and droplet volume density while satisfying geometric constraints. A compact acquisition device was then developed and tested with eight nozzle specifications under fixed pressure. Image processing algorithms—including cropping, RGB channel separation, and binarization—were employed to extract pixel area and cumulative intensity, with gravimetric measurements serving as the reference. Results showed that under optimized exposure and gain settings, features from the green and blue channels exhibited a strong linear correlation with flow rate (R² = 0.93–0.97). Based on these findings, this study demonstrates that in-flight droplet flow rate can be directly quantified from image features—a departure from conventional deposition-based approaches. The proposed method enables rapid, non-contact spray assessment using only a camera and laser module, offering a low-cost, simple-structured solution for spray system optimization and field monitoring. Full article

Three-dimensional spatial effects in deep excavations critically govern the mechanical response of retaining structures and adjacent soils, yet their quantitative characterization remains a challenge. This study systematically investigates the spatial behavior of row-pile-supported foundation pits through an integrated approach combining model tests, theoretical analysis, and numerical simulations. A novel formulation for the spatial effect influence coefficient K is derived from limit equilibrium principles and subsequently validated via ABAQUS-based finite element simulations. Model test results reveal pronounced spatial heterogeneity in earth pressure and bending moment distributions along the pit perimeter: lateral earth pressure at corner regions exceeds that at mid-side locations at equivalent depths, whereas bending moments in mid-side piles are substantially larger than those at corners. Displacement field measurements further demonstrate that corner zones, constrained bidirectionally, undergo minimal deformation, while maximum displacement occurs at the midpoints of the long sides. These observations collectively confirm the existence of a marked corner effect and a subdued side-midpoint effect under three-dimensional confinement. Complementary numerical analyses indicate that the coefficient K decreases monotonically with increasing half-angle corners and distance from the corner, thereby quantitatively capturing the decay of spatial constraint intensity. Together, these findings establish a theoretical framework for assessing excavation-induced spatial effects and provide actionable guidance for the rational design of deep foundation pit support systems. Full article

Wavelength modulation spectroscopy (WMS) is a representative implementation of tunable diode laser absorption spectroscopy (TDLAS), enabling reliable gas component analysis with concentration-related information derived from harmonic component extraction, while offering enhanced noise immunity for trace gas sensing in open environments. However, due to the strong coupling between laser wavelength and intensity, wavelength modulation inevitably introduces residual amplitude modulation (RAM), which significantly degrades measurement accuracy. To address this issue, this study introduces a RAM suppression algorithm based on multiple harmonic component decoupling (MHCD), using the second-harmonic lateral peak inclination angle (LPIA) as a characteristic indicator. Unit harmonic operators for the first, second, and third harmonics are designed, and an original harmonic reconstruction model is established via linear superposition of harmonic components. The optimal harmonic component ratio is determined at the composite operator with the maximum cross-correlation coefficient, and RAM noise is eliminated through a multi-harmonic decoupling matrix. Repetitive measurements on 22 mm pharmaceutical vials with 4% oxygen concentration demonstrate that MHCD reduces the second-harmonic LPIA from 18.07° to 8.56°. Concentration discrimination experiments conducted on seven groups of 22 mm vials with 2% concentration steps (0–12%) show that MHCD increases the true positive rate by 6–11% and decreases the false positive rate by 4–9%, confirming its effectiveness for pharmaceutical online inspection applications. Full article