Search Results (40)

In this work, the load spectra acting in the vertical direction on the hub carriers and in the horizontal longitudinal direction on the drawbar of a trailed variable chamber round baler were evaluated. To this end, each hub carrier was instrumented with appropriately calibrated strain gauge bridges. Similarly, the baler was equipped with a dynamometric towing pin, instrumented with strain gauge sensors and calibrated in the laboratory, which replaced the original pin connecting the baler and the tractor during the in-field load acquisitions. In both cases, the calibration tests returned the relationship between applied forces and output signals of the strain gauge bridges. Multiple in-field load acquisitions were carried out under typical maneuvers and operating conditions. The synchronous acquisition of a video via an onboard camera and Global Positioning System (GPS) signal allowed to observe the behaviour of the baler in correspondence of particular trends of the vertical and horizontal loads and to point out the most demanding maneuver in view of the fatigue resistance of the baler. Finally, through the application of a rainflow cycle counting algorithm according to ASTM E1049-85, the load spectrum for each maneuver was derived. Full article

The Spiny-tailed Lizard (Uromastyx aegyptia), a vulnerable species native to the desert and semi-desert regions of the Middle East, remains poorly understood, particularly regarding its daily activity patterns in northern Saudi Arabia. This study, conducted in the Ha’il region, aimed to examine these patterns, assess the influence of soil temperature on activity, and identify potential threats to the species. The results revealed that soil temperature significantly affected the lizard’s activity patterns. During spring, Spiny-tailed Lizards were more active, spending around 25% of the day engaged in various behaviours, while their activity decreased to less than 20% in summer. In autumn and winter, the lizards did not follow a consistent daily activity, becoming active only when surface temperatures exceeded 35 °C. The absence of tracks and sightings in January suggests the species enters a state of complete brumation during this month. While no predation events were recorded via trail cameras, human disturbance from livestock and vehicles was observed in spring and summer. Although the disturbance was minor, reducing this type of human-caused disturbance should be taken into consideration when designing any protection programs. Furthermore, the long-term monitoring of this lizard’s daily and seasonal activity patterns is recommended in order to better understand its adaptability to environmental changes, especially those driven by climate fluctuations. Full article

We applied UAV (Unmanned Aerial Vehicle) and ALS (Airborne Laser Scanning) remote sensing methods to identify terrain obstacles encountered during timber extraction in the skidding process with the aim of proposing accessibility solutions to the inner parts of forest stands using skidding trails. At the Vítovický žleb site, located east of Brno in the South Moravian Region of the Czech Republic, we analysed the accuracy of digital terrain models (DTMs) created from UAV LiDAR (Light Detection and Ranging), RGB (Red–Green–Blue) UAV, ALS data taken on site and publicly available LiDAR data DMR 5G (Digital Model of Relief of the Czech Republic, 5th Generation, based on airborne laser scanning, providing pre-classified ground points with an average density of 1 point/m²). UAV data were obtained using two types of drones: a DJI Mavic 2 mounted with an RGB photogrammetric camera and a GeoSLAM Horizon laser scanner on a DJI M600 Pro hexacopter. We achieved the best accuracy with UAV technologies, with an average deviation of 0.06 m, compared to 0.20 m and 0.71 m for ALS and DMR 5G, respectively. The RMSE (Root Mean Square Error) values further confirm the differences in accuracy, with UAV-based models reaching as low as 0.71 m compared to over 1.0 m for ALS and DMR 5G. The results demonstrated that UAVs are well-suited for detailed analysis of rugged terrain morphology and obstacle identification during timber extraction, potentially replacing physical terrain surveys for timber extraction planning. Meanwhile, ALS and DMR 5G data showed significant potential for use in planning the placement of skidding trails and determining the direction and length of timber extraction from logging sites to forest roads, primarily due to their ability to cover large areas effectively. Differences in the analysis results obtained using GIS (Geographic Information System) cost surface solutions applied to ALS and DMR 5G data DTMs were evident on logging sites with terrain obstacles, where the site-specific ALS data proved to be more precise. While DMR 5G is based on ALS data, its generalised nature results in lower accuracy, making site-specific ALS data preferable for analysing rugged terrain and planning timber extractions. However, DMR 5G remains suitable for use in more uniform terrain without obstacles. Thus, we recommend combining UAV and ALS technologies for terrain with obstacles, as we found this approach optimal for efficiently planning the logging-transport process. Full article

Autumn phenology plays a crucial role in shaping the capacity for carbon sequestration. However, understories, a vital yet often neglected ecosystem component, have complicated autumn phenology prediction. We address the challenge of monitoring understory phenological dynamics by using a UVL4 trail camera and selecting appropriate deriving processes and vegetation indices (VIs). We found the understory photoperiod was on average 1.88 h shorter than the canopy’s, while the understory temperature was 2.11 °C higher than the canopy’s open-air temperature. The maximum temperature inside the understories was on average 1.37 °C lower than in open-air conditions. Specifically, the 60% quantile of the daily VI in July and the 15% quantile in November effectively captured the prolonged minimum and the minimum in the VI time series when applying logistic modeling. The excess green vegetation index (ExG) outperformed other VIs in estimating understory greenness change. The cold degree days model (CDD) and low-temperature and photoperiod multiplicative model (TPM) revealed that senescence progressed from the upper crown downwards, causing over 13 days of lag in the understory. These findings offer a new perspective on quantifying autumn phenology in subtropical forests and provide insights into asynchronous changes in vertical microclimatic gradients in Earth system and vegetation models. Full article

Identifying population-level relationships between predators and their prey is often predicated on having reliable population estimates. Camera-trapping is effective for surveying terrestrial wildlife, but many species lack individually unique natural markings that are required for most abundance and density estimation methods. Analytical approaches have been developed for producing population estimates from camera-trap surveys of unmarked wildlife; however, most unmarked approaches have strict assumptions that can be cryptically violated by survey design characteristics, practitioner choice of input values, or species behavior and ecology. Using multi-year datasets from populations of an unmarked predator and its co-occurring unmarked prey, we evaluated the consequences of violating two requirements of the random encounter model (REM), one of the first developed unmarked methods. We also performed a systematic review of published REM studies, with an emphasis on predator–prey ecology studies. Empirical data analysis confirmed findings of recent research that using detections from non-randomly placed cameras (e.g., on trails) and/or borrowing movement velocity (day range) values caused volatility in density estimates. Notably, placing cameras strategically to detect the predator, as is often required to obtain sufficient sample sizes, resulted in substantial density estimate inflation for both the predator and prey species. Systematic review revealed that 91% of REM density estimates in published predator–prey ecology studies were obtained using camera-trap data or velocity values that did not meet REM requirements. We suggest considerable caution making conservation or management decisions using REM density estimates from predator–prey ecology studies. Full article

We investigated the survival of cubs in a wild Indian leopard (Panthera pardus fusca) population in the Jhalana Reserve Forest (JRF), India. The research focuses on analyzing the survival of leopard cubs during their first two years of life. Survival functions were estimated using the Kaplan–Meier method based on data collected with trail cameras over four years from 2018 to 2021. We found that the mean survival probability of cubs during the first year of life was 0.739, indicating that this period is particularly challenging for their survival. In the second year, the survival probability increased to 0.831, reflecting an improvement in survival as the cubs grew older. The combined survival rate over the two-year period, calculated as the product of the first- and second-year survival rates, was 0.618. These findings highlight the critical periods in the early life stages of leopard cubs, which are essential for developing effective conservation strategies in fragmented habitats to enhance their survival. Full article

Seasonality drives natural processes, impacting environmental factors like temperature and resource availability, leading to shifts in wildlife communities. The Andean dry forests exhibit a marked seasonality, with a dry and cold season (May–September) and a warm, wet season (October–April). In a year-long remote camera survey in Southern Bolivia, we identified 29 medium to large mammal species, 18 outside their known distribution ranges. While overall species richness remained stable, photographic records varied between seasons. Capture rates, reflecting species richness and abundance, were more influenced by season and habitat. Wet season rates were lower, but higher in all other habitats compared to the mountain bush and grasslands. Rates increased with altitude and distance to hiking trails, but decreased with increasing distance from main roads. Medium to large mammals were more active during the dry season, indicating adjustments in response to seasonal changes. Our results suggest a cumulative impact of various factors beyond mere seasonality, and call for adjustments in global species distributions. Moreover, emphasize the need for biodiversity monitoring in dry forest habitats, particularly regarding responses to environmental shifts and human-induced alterations. Full article

The significant increase in hiking, wood extraction, and transportation activities exerts a notable impact on the environmental balance along trails and forest roads in the form of soil degradation. The aim of this study was to develop a Deformation Classification Model for the surface of a multi-use trail, as well as to calculate sediment deposition and generate a flood hazard map in a partially forested region. The eBee X mapping Unmanned Aerial Vehicle (UAV) equipped with the senseFly S.O.D.A. 3D camera and Real-Time Kinematic (RTK) technology flew over the study area of 149 ha in Northern Greece at an altitude of 120 m and achieved a high spatial resolution of 2.6 cm. The specific constellation of fixed-wing equipment makes the use of ground control points obsolete, compared to previous, in most cases polycopter-based, terrain deformation research. Employing the same methodology, two distinct classifications were applied, utilizing the Digital Surface Model (DSM) and Digital Elevation Model (DEM) for analysis. The Geolocation Errors and Statistics for Bundle Block Adjustment exhibited a high level of accuracy in the model, with the mean values for each of the three directions (X, Y, Z) being 0.000023 m, −0.000044 m, and 0.000177 m, respectively. The standard deviation of the error in each direction was 0.022535 m, 0.019567 m, and 0.020261 m, respectively. In addition, the Root Mean Square (RMS) error was estimated to be 0.022535 m, 0.019567 m, and 0.020262 m, respectively. A total of 20 and 30 altitude categories were defined at a 4 cm spatial resolution, each assigned specific ranges of values, respectively. The area of each altitude category was quantified in square meters (m²), while the volume of each category was measured in cubic meters (m³). The development of a Deformation Classification Model for the deck of a trail or forest road, coupled with the computation of earthworks and the generation of a flood hazards map, represents an efficient approach that can provide valuable support to forest managers during the planning phase or maintenance activities of hiking trails and forest roads. Full article

Fishing nets are dangerous obstacles for an underwater robot whose aim is to reach a goal in unknown underwater environments. This paper proposes how to make the robot reach its goal, while avoiding fishing nets that are detected using the robot’s camera sensors. For the detection of underwater nets based on camera measurements of the robot, we can use deep neural networks. Passive camera sensors do not provide the distance information between the robot and a net. Camera sensors only provide the bearing angle of a net, with respect to the robot’s camera pose. There may be trailing wires that extend from a net, and the wires can entangle the robot before the robot detects the net. Moreover, light, viewpoint, and sea floor condition can decrease the net detection probability in practice. Therefore, whenever a net is detected by the robot’s camera, we make the robot avoid the detected net by moving away from the net abruptly. For moving away from the net, the robot uses the bounding box for the detected net in the camera image. After the robot moves backward for a certain distance, the robot makes a large circular turn to approach the goal, while avoiding the net. A large circular turn is used, since moving close to a net is too dangerous for the robot. As far as we know, our paper is unique in addressing reactive control laws for approaching the goal, while avoiding fishing nets detected using camera sensors. The effectiveness of the proposed net avoidance controls is verified using simulations. Full article

Harbour seals (Phoca vitulina) are part of the Norwegian coastal ecosystem and can be observed on skerries, islands, and sandbanks along the coastline, sometimes in close proximity to inhabited areas. In this study, we used time-lapse camera surveys to monitor the haulout patterns of harbour seals at two selected sites in the Norwegian Skagerrak, Lyngør and Østre Bolæren, over 12 and 4 months, respectively. The goal was to investigate how the number of seals hauling out on land varied seasonally and how it was influenced by environmental parameters (wind speed, air temperature, and water level), the time of the day, and anthropogenic disturbances. As expected, the number of seals hauled out increased with increasing air temperature and decreased with increasing wind speed and water level. Clear circadian patterns in the seal haulout behaviour were identified during autumn and winter when a significantly higher number of seals were observed on land at night. Moreover, haulout patterns showed significant seasonal variation, with a peak in haul outs being observed during the moulting season in August. Despite an expected high usage of land during the breeding season in early summer, the number of seals hauled out at the Lyngor study site was low during this period, especially during weekends and summer holidays, maybe due to increased disturbance from boats. This study provides valuable insights into the factors influencing the haulout behaviour of the species in the region and suggests possible effects of human disturbance on harbour seal behaviour in the area. Full article

Background: Trail running socks with the same fibers and design but with different separations of their three-dimensional waves could have different thermoregulatory effects. Therefore, the objective of this study was to evaluate the temperatures reflected on the sole of the foot after a mountain race with the use of two models of socks with different wave separations. Material and Methods: In a sample of 34 subjects (twenty-seven men and seven women), the plantar temperature was analyzed with the thermal imaging camera Flir E60bx^® (Flir systems, Wilsonville, OR, USA) before and after running 14 km in mountainous terrain at a hot temperature of 27 °C. Each group of 17 runners ran with a different model of separation between the waves of the tissue (2 mm versus 1 mm). After conducting the post-exercise thermographic analysis, a Likert-type survey was conducted to evaluate the physiological characteristics of both types of socks. Results: There was a significant increase in temperature in all areas of interest (p < 0.001) after a 14 km running distance with the two models of socks. The hallux zone increased in temperature the most after the race, with temperatures of 8.19 ± 3.1 °C and 7.46 ± 2.1 °C for the AWC 2.2 and AWC 3, respectively. However, no significant differences in temperature increases were found in any of the areas analyzed between the two groups. Runners perceived significant differences in thermal sensation between AWC 2.2 socks with 4.41 ± 0.62 points and AWC 3 with 3.76 ± 1.03 points (p = 0.034). Conclusion: Both models had a similar thermoregulatory effect on the soles of the feet, so they can be used interchangeably in short-distance mountain races. The perceived sensation of increased thermal comfort does not correspond to the temperature data. Full article

Airborne wind energy systems using flexible membrane wings have the advantages of a low weight, small packing volume, high mobility and rapid deployability. This paper investigates the aero-structural deformation of a leading edge inflatable kite for airborne wind energy harvesting. In the first step, a triangular two-plate representation of the wing is introduced, leading to an analytical description of the wing geometry depending on the symmetric actuation state. In the second step, this geometric constraint-based model is refined to a multi-segment wing representation using a particle system approach. Each wing segment consists of four point masses kept at a constant distance along the tubular frame by linear spring-damper elements. An empirical correlation is used to model the billowing of the wing’s trailing edge. The linear spring-damper elements also the model line segments of the bridle line system, with each connecting two point masses. Three line segments can also be connected by a pulley model. The aerodynamic force acting on each wing segment is determined individually using the lift equation with a constant lift coefficient. The particle system model can predict the symmetric deformation of the wing in response to a symmetric actuation of the bridle lines used for depowering the kite (i.e., changing the pitch angle). The model also reproduces the typical twist deformation of the wing in response to an asymmetric line actuation used for steering the kite. The simulated wing geometries are compared with photogrammetric information taken by the onboard video camera of the kite control unit, focusing on the wing during flight. The results demonstrate that a particle system model can accurately predict the geometry of a soft wing at a low computational cost, making it an ideal structural building block for the next generation of soft wing kite models. Full article

The White-tailed eagle, an apex predator, is currently recovering its populations across Europe and has already reached high numbers in many countries. This led to the saturation of eagles in optimal habitats and their encroachment on suboptimal ones. We aimed to compare the diet of White-tailed eagles in optimal and suboptimal conditions in northeastern Poland to investigate how population development affected prey composition, which is expected to be lacking in suboptimal eagle territories. We have monitored eagle nests with trail cameras to investigate their diet objectively and precisely. In order to compare territories of different quality, we have conducted modeling of habitat suitability using data on nest locations prior to their saturation. Using recorded photos of the prey, we measured their size and estimated their weight to check if the size and biomass of the prey are comparable between optimal and suboptimal territories. We found that eagles in the latter conditions were not limited by prey biomass but turned to alternative prey and brought larger prey. The alternative prey were large birds such as White storks and Common cranes, but also chicks of other avian predators that were robbed from their nests. Most probably, eagles cope with a lack of optimal prey by ranging farther and exploring non-optimal foraging habitats. We conclude that the diet flexibility of White-tailed eagle enables him to still increase its numbers despite already high densities. Our study also shows that this species might possibly impact the White stork population, as seen in the case of the Black stork and some seabird species. Full article

In gas metal arc welding (GMAW), the weld bead shape is an important factor that is directly related to the weld quality of welded joints. This study investigates the effects of process parameters, including welding speed (WS) and leading and trailing wire feed rates (WFR), on the weld bead shape, including the leg length and penetration depth, in the tandem GMAW of aluminum 5083-O alloy. An asynchronous direct current–direct current pulse tandem GMAW system and a tandem GMAW torch were designed and applied to improve welding productivity and welding quality. Response surface methodology was used to analyze the effects of the process parameters on the weld bead shape and to estimate regression models for predicting the weld bead shape. As a result of observing arc behavior using a high-speed camera, it was confirmed that the leading WFR affects the penetration depth and the trailing WFR affects the leg length. The coefficient of determination (R²) of the regression models was 0.9414 for the leg length and 0.9924 for the penetration depth. It was also validated that the estimated models were effective in predicting the weld bead shape (leg length and penetration depth) representative of weld quality in the tandem GMAW process. Full article

Insufficient research has been conducted on musk deer species across their distribution range, primarily because of their elusive behaviour and the fact they occupy remote high-altitude habitats in the Himalayas above 2500 m. The available distribution records, primarily derived from ecological studies with limited photographic and indirect evidence, fail to provide comprehensive information on the species distribution. Consequently, uncertainties arise when attempting to determine the presence of specific taxonomic units of musk deer in the Western Himalayas. This lack of knowledge hampers species-oriented conservation efforts, as there need to be more species-specific initiatives focused on monitoring, protecting, and combatting the illegal poaching of musk deer for their valuable musk pods. We used transect surveys (220 trails), camera traps (255 cameras), non-invasive DNA sampling (40 samples), and geospatial modelling (279 occurrence records) to resolve the taxonomic ambiguity, and identify the suitable habitat of musk deer (Moschus spp.) in Uttarkashi District of Uttarakhand and the Lahaul–Pangi landscape of Himachal Pradesh. All the captured images and DNA-based identification results confirmed the presence of only Kashmir musk deer (KDM) (Moschus cupreus) in Uttarakhand and Himachal Pradesh. The results suggest that KMD inhabit a narrow range of suitable habitats (6.9%) of the entire Western Himalayas. Since all evidence indicates that only KMD are present in the Western Himalayas, we suggest that the presence of other species of musk deer (Alpine musk deer and Himalayan musk deer) was wrongly reported. Therefore, future conservation plans and management strategies must focus only on KMD in the Western Himalayas. Full article