Search Results (1,521)

This paper presents the design, optimization, and performance evaluation of a Satellite-Based Augmentation System (SBAS) ground segment tailored to Colombia’s air navigation infrastructure, with emphasis on ionospheric anomalies in equatorial latitudes. The configuration comprises six Reference Stations (RIMS), strategically sited via geometric dilution of precision (GDOP) minimization and airspace demand models from ADS-B data. A simulation suite—integrating STK^®, Radio Mobile™, and Stanford-ESA certified monitors—quantifies service volume, link margins, and protection level compliance. Ionospheric threat characterization uses regional scintillation datasets (σln ≈ 0.36, ROTI₉₅ ≈ 85 mm/km), informing GIVE inflation and dual-frequency pseudorange integrity validation. Simulations confirm the system sustains ≥ 99.8% APV-I availability over the CAR/SAM FIR, with Horizontal and Vertical Protection Levels (HPL/VPL) bounded below 28 m and 46 m. Uplink integrity and GEO broadcast continuity are modelled under worst-case masking and multipath, confirming ICAO Annex 10 SARPs compliance. The architecture achieves a high performance-to-cost ratio, enabling nationwide SBAS coverage with a 65% cost reduction versus legacy navaids. The system is forward-compatible with dual-frequency multi-constellation SBAS (DFMC), supporting future APV-II scalability. These results position Colombia as a regional node for GNSS augmentation, fostering safety, efficiency, and procedural harmonization. Full article

This study investigates the crack damage evolution in Chinese fir using an anisotropic bilinear cohesive zone-based constitutive model. The crack initiation and propagation processes were numerically modeled and simulated, and the results were validated through double cantilever beam (DCB) fracture tests. By exploiting the bijective relationship between the equivalent linear elastic fracture mechanics (LEFM) resistance curve (R-curve) and the cohesive softening law, the bilinear cohesive parameters were inversely identified from experimental data. The simulation results show good agreement with experimental observations in terms of crack path, propagation rate, and failure mode. The accuracy of the maximum load simulation results for mode I fracture of wood beams is 96.8%. These results further demonstrate the accuracy and applicability of the proposed cohesive zone model in describing crack propagation behavior in Chinese fir and provide a reliable theoretical and numerical framework for predicting fracture performance in timber structures. Full article

As a core technology in 3D measurement, laser stripe center extraction is widely applied in industrial inspection, robot navigation, and biomedicine. However, traditional methods struggle to balance denoising effectiveness and positioning accuracy when handling complex noise and non-uniform width stripes. To address this bottleneck, this paper proposes a denoising-adaptive weighted average width stripe center extraction algorithm based on an improved Hessian Matrix, integrating deep learning with traditional image processing for high-precision extraction. A U-Net++ denoising network with a spatial attention module is designed to focus on stripe regions, supplemented by a distance-aware mechanism that dynamically adjusts denoising intensity based on pixel-stripe distance. For center extraction, an improved Hessian Matrix algorithm is proposed, incorporating a curvature-adaptive FIR filter and adaptive weighted average width calculation to adapt to stripe morphology changes. Experimental results show the algorithm outperforms comparative methods, achieving 35.26 dB (PSNR), 0.962 (SSIM), and 6.14 (RMSE) in denoising. Under 200 μs, 500 μs, 1000 μs, and 1500 μs exposure conditions, the absolute radius errors are reduced to 0.2052 mm, 0.1743 mm, 0.0268 mm, and 0.0281 mm, respectively, verifying its reliability and stability in practical applications. Full article

Currently, there is no curative medication for idiopathic pulmonary fibrosis (IPF), and therapeutic interventions for IPF are hindered by limited efficacy and severe adverse side effects. Far Infrared Radiation (FIR), an invisible form of electromagnetic energy, has garnered increasing attention for its multiple biological effects. However, its therapeutic benefits and the underlying mechanisms of IPF have not been investigated. In the present study, we established a mouse model of bleomycin-induced pulmonary fibrosis (BIPF) to assess the efficacy of FIR in attenuating BIPF. The results showed that FIR therapy significantly improved the general condition of the mice and protected pulmonary function by ameliorating lung fibrosis, collagen deposition and excessive inflammation. Moreover, FIR could alleviate fibroblast-to-myofibroblast differentiation (FMD), the epithelial–mesenchymal transition (EMT) and angiogenesis in BIPF mice. These beneficial effects were notable both in the pro-fibrotic inflammatory stage and the following fibrotic stage. Mechanistically, FIR exerted anti-inflammatory and anti-fibrotic effects through modulating the p53/TGF-β signaling pathway. Overall, this study elucidates the anti-fibrotic activity and the potential molecular mechanisms of FIR in treating BIPF, providing a therapeutic strategy of convenient, non-invasive physical therapy for alleviating IPF. Of greater significance, the findings of this study display the promising future applications of FIR in managing the physiopathology of various chronic diseases. Full article

Wildland fires, including surface and crown fires, present significant challenges for ecosystems and forest management. Accurate fire modelling is crucial for risk assessment and mitigation strategies. The Fire Dynamics Simulator (FDS) v6.8.0, developed by the National Institute of Standards and Technology (NIST), is a physics-based model that simulates fire behaviour by incorporating advanced physics and chemistry. However, its reliability requires thorough validation. This study validates FDS 6.8.0’s performance in modelling both surface fires and single tree burning. Two separate simulation sets were conducted. For surface fires, pine needle fuel beds were used at a laboratory scale to examine fire behaviour on slopes of 0°, 10°, and 20°. The results were validated against experimental data. A burning Douglas fir tree was simulated, and the results were compared with experimental measurements. The surface fire simulations at 0° and 10° slopes showed strong agreement with experimental data. In single-tree burning, both experimental and simulated results exhibited similar trends, with a rapid increase to a peak mass-loss rate (MLR) followed by a gradual decline. Validating FDS 6.8.0 forms an essential first step toward supporting the investigation of complex wildland fire behaviour, such as surface-to-crown fire transition, canyon fire, and dynamic escalation, using the same FDS version. Full article

Phosphorus (P) deficiency in forest soils is a key constraint on the sustainable management and productivity of Chinese fir (Cunninghamia lanceolata) plantations. This study investigated how P limitation alters the reciprocal exchange of “photosynthetic carbon and mineral phosphorus” between Chinese fir and arbuscular mycorrhizal fungi (AMF) when the focal plant grows adjacent to neighbors with different degrees of relatedness. An indoor pot experiment simulating heterogeneous P supply was conducted using clonal seedlings of Chinese fir No. 36 as the focal plant, with Chinese fir No. 36, Chinese fir No. 41, and Schima superba as neighboring plants to establish three two-plant combinations: a kin pair (No. 36 + No. 36), a close-kin pair (No. 36 + No. 41), and an unrelated-kin pair (No. 36 + S. superba). Funneliformis mosseae was inoculated into the shared root-zone room connecting the two plants, and the neighbor was subjected to a gradient of P limitation (sufficient P, low P, and zero P). Meanwhile, the focal No. 36 plant received ¹³CO₂ pulse labeling to form a “Chinese fir–AMF–P-limited neighbor” symbiotic network in which No. 36 served as the ¹³C donor. AMF colonization, seedling growth, and changes in ¹³C enrichment and P concentration in plant tissues of the focal plant were quantified. Neighbor P limitation significantly increased AMF colonization in roots and whole-plant P concentration of the focal Chinese fir. Following ¹³CO₂ pulse labeling, whole-plant ¹³C enrichment of the focal plant increased significantly under the neighbor zero P treatment, suggesting enhanced carbon allocation under severe neighbor P limitation. Moreover, under the neighbor zero P treatment, focal plants grown with an unrelated-kin neighbor showed significant increases in stem P concentration (1.86 g·kg⁻¹) and stem atom% ¹³C (1.50%), whereas focal plants grown with a kin neighbor exhibited a significant increase in root Atom% ¹³C (1.29%). These patterns indicate that neighbor relatedness may modulate carbon allocation and P acquisition within the mycorrhizal network: in the kin context, the focal plant tended to allocate more photosynthetic carbon belowground and may partially subsidize the AMF carbon demand (i.e., a higher C reward), coinciding with a relatively weaker P accumulation in its own tissues; in contrast, in the unrelated kin context, carbon allocation shifted toward stems and was associated with strengthened P accumulation in stem tissues. Overall, the results highlight the dynamic nature of AMF-mediated carbon–nutrient reciprocity across hosts of contrasting relatedness and provide new insights into how mycorrhizal networks may facilitate plant adaptation to nutrient limitation. Full article

Silver fir bark (Abies alba Mill.) is an underutilized renewable resource containing valuable extractives and polyphenols of industrial importance. This study compared the influence of two storage methods on the extraction of total hydrophilic extractives content (TEC) and total polyphenols content (TPC) from silver fir bark samples. Bark samples were collected from two storage types: bark left on stem sections and stored under cover (B-D), and mechanically removed industrial bark stored outdoors (B-IS), over a 12-month period with monthly sampling and extraction, followed by measurements of TEC and TPC using gravimetric and spectrophotometric methods. B-D samples showed no statistically significant decrease in TEC or TPC during one year of storage, while B-IS samples exhibited substantial losses, with TEC decreasing by more than half (50.82%) and TPC by 65.68%, most rapidly within the first 3 months when precipitation-driven leaching and degradation processes were obviously most pronounced. These results demonstrate that bark removed before storage is much more susceptible to degradation and leaching of the hydrophilic extractives than bark retained on logs, confirming that mechanical disintegration and exposure to weathering accelerate the loss of valuable extractives and polyphenols. A strong TEC–TPC correlation (r = 0.67–0.81, p < 0.0001) provides a practical methodological approach for rapid biomass quality screening. Overall, the findings offer quantitative guidance for optimizing debarking timing and storage practices to preserve extractive yield and enhance the efficiency of bark-based biorefinery processes. Full article

In many cases, the removal of individual frequency components from a signal spectrum is achieved using notch and multinotch filters. One of the main disadvantages of such filters is the occurrence of transient states, which depend, among other factors, on the filter order and selectivity, i.e., the bandwidth of the stopband. In this paper, the authors present a method for synthesizing a finite impulse response (FIR) multinotch filter based on a prototype infinite impulse response (IIR) notch filter. The proposed approach is characterized by a significant reduction in the influence of transient effects on the filter response, achieved through the iterative determination of nonzero initial conditions. This allows the dynamic performance of the filter to be improved without compromising its frequency response. Furthermore, the proposed filter structure is characterized by having a lower filter order than conventional filtering structures while maintaining satisfactory filtration quality. To demonstrate the properties of the proposed structure, computer simulations were performed and filtration quality metrics were evaluated. The obtained results indicate that the proposed structure outperforms classical filtering methods by ensuring faster stabilization of the response during the transient state. Moreover, it was demonstrated that the proposed method of reducing the FIR filter order has only a minor effect on filtration quality. Full article

Mixed forests provide several ecosystem service benefits, and they also often show higher productivity than pure forests. In mixed forests, several interactions among tree species occur, with size-symmetric and size-asymmetric competition being particularly important. We studied diameter growth of European beech in pure stands and in mixtures with oak, maple, pine, spruce, fir, and spruce and fir combined on extremely diverse beech sites in Slovenia, using forest inventory sample plots (n = 26,793, 500 m² each). For each mixture, we developed models of 10-year individual tree diameter increment (id) using natural splines and incorporating tree, competition, stand, site, and climate variables that were mainly gathered in regular forest inventories. Competition was represented using simple indices: stand basal area (BA) for size-symmetric competition, basal area of overtopping trees (BAL) for size-asymmetric competition, and reduced competition due to harvesting (CUT). The models revealed differences among mixtures and a strong influence of competition. Id was among the lowest in pure stands and substantially higher in mixtures, indicating strong intraspecific competition. Overall, size-symmetric competition was more influential, but size-asymmetric competition appeared important in some mixtures. We recommend growing beech in mixtures with other species and applying a forest management approach that accounts for competition symmetry, which proved crucial in each mixture. Full article

Seed wings are widely recognized for facilitating dispersal and influencing germination in angiosperms, but their functional role in gymnosperm germination is poorly understood. To assess the effect of seed wings on the germination ecology of Smith fir (Abies georgei var. smithii), we evaluated the germination of three seed treatments—intact seeds, mixed seeds (de-winged seeds mixed with detached wings), and de-winged seeds—under varying light and temperature conditions. Results showed that de-winged seeds achieved a final germination percentage of 48.5 ± 5.0%, which was significantly higher than that of intact seeds (26.0 ± 2.4%) and mixed seeds (32.5 ± 3.5%) (p < 0.001), confirming that seed wings significantly inhibit germination. There was no significant difference between intact and mixed seeds, and both were significantly lower than de-winged seeds (p < 0.001), suggesting that germination inhibition is likely mediated by chemical inhibitors in the wings rather than mechanical restriction. Optimal germination occurred at 15/2 °C–25/5 °C, while light significantly enhanced germination under cold conditions (5/1 °C), indicating conditional dormancy. These findings suggest that seed wings optimize the regulation of germination timing by imposing chemical inhibition that, combined with conditional dormancy, delays germination until favorable spring conditions, reflecting an adaptive strategy to seasonal environmental cues in subalpine ecosystems. Full article

The accurate and non-invasive measurement of moisture content in wood is essential for the preservation of historical and artistic artifacts. This study presents the calibration of a planar Microwave Planar Capacitive Coupled Ring Resonator (MPCCRR) designed to indirectly and non-destructively assess the water content in wood samples. The method relies on analyzing shifts in the resonant frequencies and variations in the transmission parameter |S21| resulting from changes in the material’s dielectric permittivity. After preliminary characterization via parametric simulations (εr = 1–10) and validation with low-permittivity reference materials, the sensor was tested on three wood species (poplar, fir, beech), including measurements at two sensor positions and with different grain orientations. The results demonstrate a monotonic, repeatable response to increasing moisture content with frequency shifts up to ≈220 MHz and normalized sensitivities ranging from 3 to 9 MHz/% water content, depending on species and measurement position. Position 2 showed the greatest sensitivity due to stronger field–sample interaction, while Position 1 provided a quasi-isotropic response with excellent repeatability. Linear regression analyses revealed good correlations between the frequency shifts and the gravimetric water content (R² ≥ 0.85). The MPCCRR sensor therefore proves to be a promising tool for the non-invasive monitoring of wood moisture, which is particularly suitable for the low-moisture range encountered in cultural heritage conservation, with an estimated moisture uncertainty of 0.12–0.35% under controlled laboratory conditions. Full article

Among the options to improve the establishment of jalapeno pepper (Capsicum annuum L.), physical biostimulants such as far-infrared bioceramics (FIR) and static magnetic fields (MF) have emerged as non-chemical alternatives. This study evaluated, under in vitro conditions, the individual and combined effects of FIR and positive or negative MF on seed germination dynamics, early seedling morphology, water status, and photosynthetic pigments. A completely randomized design with eight treatments was implemented, including FIR applied continuously throughout the entire experimental period, positive or negative MF applied for 24 h (MF⁺₂₄, MF⁻₂₄), and FIR + MF combinations under continuous or 24 h exposure regimes (n = 7). Germination percentage, mean germination time (MGT), mean germination rate (MGR), germination index (GI), morphological variables, water content (WC), and photosynthetic pigments were measured; ANOVA/alternative tests (a = 0.05), Principal Components Analysis (PCA) and exploratory Spearman’s correlations were used to assess relationships among the evaluated variables. Germination percentage did not change (97.64%), but kinetics did: FIR + MF⁻₂₄ reduced MGT to 4.32 d, FIR increased MGR to 5.83 seeds day⁻¹ (+11.69%), and FIR₂₄ + MF⁺₂₄ showed the highest GI (4.57). For morphological, MF⁺₂₄ increased hypocotyl length (+16.29%), FIR increased collar diameter (+27.27%), and FIR + MF⁻₂₄ increased cotyledon area (25%), and FIR increased chlorophyll a (+139%), chlorophyll b (+141%), and carotenoids (+114%). PCA explained 66.9% of the variance, grouping FIR with growth variables and FIR + MF combinations with WC and pigments. Inferences are limited to one cultivar and controlled in vitro conditions. This study provides novel quantitative evidence that continuous and short-term applications of FIR and MF modulate germination dynamics and early physiological traits without altering final germination, related to structure and pigments, without changing final germination percentage. Full article

Christmas tree growers are concerned with improving establishment of their plantations. Here, we report the results of a series of on-farm trials conducted with grower-cooperators in the Pacific Northwest (PNW) and Great Lakes (Michigan—MI) regions to determine the efficacy of treatments at planting on improving tree survival and growth in Christmas tree plantations. Cooperating growers planted species that were typical for each region (Fraser fir in the Great Lakes and Douglas-fir and noble fir in the PNW) and managed the plantings using standard cultural practices, aside from test treatments. Test treatments varied between locations and years but included wood chip mulch, shade blocks, an anti-transpirant, biochar, fertilizers, and various root dips including polymer gels, mycorrhizae, and bio-stimulants. Overall, treatments that directly modified the tree environment (i.e., mulch and shade blocks) provided the most consistent benefit to tree survival and growth. In Michigan, mulching increased survival by 5% on non-irrigated farms and increased second-year shoot growth by ~3 cm. In the PNW trials, mulching increased survival of noble fir seedlings more than Douglas-fir seedlings. Installing controlled release fertilizer packets at planting increased initial growth of Douglas-firs. Application of root dips prior to planting did not improve tree survival or growth relative to dipping tree roots in water (control). Based on our results, we conclude that treatments that conserve soil moisture (mulch) or reduce tree water loss (shade blocks) offer the most direct opportunity for growers to improve initial tree survival and growth. Full article

The shift toward Industry 5.0 places human-centred and digitally integrated metrology at the core of modern manufacturing, particularly in the automotive sector, where portable Laser Line Triangulation (LLT) systems must combine accuracy with operator usability. This study addresses the challenge of operator-induced variability by evaluating how algorithmic strategies and mechanical support features jointly influence the performance of a portable LLT device derived from the G3F sensor. A comprehensive Measurement System Analysis was performed to compare three feature extraction algorithms—GC, FIR, and Steger—and to assess the effect of a masking device designed to improve mechanical alignment during manual measurements. The results highlight distinct algorithm-dependent behaviours in terms of repeatability, reproducibility, and computational efficiency. More sophisticated algorithms demonstrate improved sensitivity and feature localisation under controlled conditions, whereas simpler gradient-based strategies provide more stable performance and shorter processing times when measurement conditions deviate from the ideal. These differences indicate a trade-off between algorithmic complexity and operational robustness that is particularly relevant for portable, operator-assisted metrology. The presence of mechanical alignment aids was found to contribute to improved measurement consistency across all algorithms. Overall, the findings highlight the need for an integrated co-design of algorithms, calibration procedures, and ergonomic aids to enhance repeatability and support operator-friendly LLT systems aligned with Industry 5.0 principles. Full article