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This study aimed to assess the hydrological response and resilience of watersheds in a neotropical region to identify regions sensitive to climate variations, enabling the development of adaptive strategies in response to global environmental changes. This study applied Budyko's framework using Fuh's hydrological model rewritten by Zhou to estimate hydrological response and Budyko's metrics (deviation and elasticity) to estimate hydrological resilience to climatic changes in 26 watersheds in southeastern Brazil. The proposed modeling was able to capture the differences among the watersheds, with "m" values ranging from 1.79 to 3.63. It was possible to rank the hydrological resilience from low to high across watersheds using Budyko's metrics, where the highest values of elasticity were found in watersheds with a higher percentage of forest cover. The sensitive analyses showed that watersheds with higher "m" values are more sensitive to changes in precipitation and potential evapotranspiration. The results also demonstrate that mean elevation and stream density were two key variables that influence the "m" value; these physiographic characteristics may alter the water and energy balance of the watershed affecting the water yield. A relationship between watershed's hydrological response and resilience was proposed to identify critical areas for the stability of water yield in the watersheds, providing a guide for public policy and suggesting ways to help the management of water resources in watersheds. [ABSTRACT FROM AUTHOR]

This paper addresses a class of uncertain nonlinear systems with disturbances that are challenging to model by proposing a novel model-free adaptive sliding mode control (MFASMC) scheme based on a discrete-time extended state observer (DESO). Initially, leveraging the pseudo partial derivative (PPD) concept in the model-free adaptive control (MFAC) framework, the discrete-time nonlinear model is converted into a full-form dynamic linearization (FFDL) model. Secondly, using the FFDL data model, a discrete sliding mode controller is designed. A discrete integral sliding mode surface is chosen to mitigate chattering during the reaching phase, and a hyperbolic tangent function with minimal slope variation is selected for smoother switching control. Furthermore, a DESO is designed to estimate uncertainties in the discrete system, enabling real-time compensation for the controller. Finally, a genetic optimization algorithm is employed for parameter tuning to minimize the time cost associated with selecting control parameters. The design process of this scheme relies solely on the data of the controlled system, without depending on a mathematical model. The proposed DESO-MFASMC scheme is tested through simulations using a typical numerical equation and the existing EFG-BC/320 electric heavy-duty forklift from the Quzhou Special Equipment Inspection Center. Simulation results show that the proposed method is significantly superior to the traditional MFAC and PID control methods in tracking accuracy and robustness when dealing with nonlinear disturbance of the system. The DESO-MFASMC scheme proposed in this paper not only shows its advantages in theory but also verifies its effectiveness and practicability in engineering through practical application. [ABSTRACT FROM AUTHOR]

Accurately estimating the volume of woody vegetation is critical for assessing fuel characteristics and associated wildfire risks in shrublands. However, few studies have investigated the branch volume of multi-stemmed shrubs, a dominant life form in wildfire-prone drylands. This study predicts branch volume using the inflection point of branch diameter. This inflection point, identified using the "Segmented" package in R, marks the transition from a gradual decrease to a significant reduction in diameter along the stem. The volume of branch segment above this point is calculated as a cone, and below it, a cylinder. We validated this method on various species such as Caragana korshinskii, Salix psammophila, and Vitex negundo. Good estimations were achieved with an average 19.2% bias relative to reference branch volumes, outperforming conventional methods that subjectively treated the whole branch as either a cylinder (96.9% bias) or a cone (−34.4% bias). We tallied branches by basal diameter and provided inventories for easily locating the inflection point, as well as using two-way branch volume tables for rapid volume predictions in shrubland. In general, we developed an effective method for estimating branch volumes of multi-stemmed shrubs, enabling its application to larger-scale shrubland volumetric prediction. This advancement supports wildfire hazard assessment and informs decision-making in fuel treatments. [ABSTRACT FROM AUTHOR]

Accurately estimating aboveground biomass (AGB) in tropical forests is vital for managing the threats posed by deforestation, degradation, and climate change. However, challenges persist in accurately estimating AGB in high AGB regions. This study aims to accurately estimate the AGB of regions with high AGB by using spatial statistical analyses based on AGB estimates made by machine‐learning fusion of multisource data. We hypothesize that incorporating dominant auxiliary factors in the analysis increases the estimation accuracy. This study focuses on tropical forests located in Longyan, Fujian Province, China, covering an area of 19,028 km2. Multisource data are used, including airborne laser scanning, the Shuttle Radar Topography Mission digital elevation model, the Landsat Operational Land Imager, and the National Forest Inventory. Based on GeogDetector's spatial covariance matrix and the spatial similarity principle, we identify key auxiliary factors (dominant tree species, canopy closure, and herbaceous cover) and investigated how auxiliary variables can improve estimation accuracy. Empirical Bayesian kriging regression prediction introduces the main auxiliary factors to refine AGB estimates. These refinements significantly enhance the accuracy of AGB estimates, particularly for high AGB, resulting in a 0.1 increase in R2, a 7.0% reduction in root mean square error, a 13.5% reduction in mean square error, and a 6.6% reduction in mean absolute error when compared with the AGB estimates obtained by using machine learning to fuse multisource data. Thus, incorporating spatial statistical analysis into the integration of multisource data and machine learning for AGB estimation can enhance the accuracy of high‐AGB estimates in intricate forest structures, resulting in precise AGB maps. Plain Language Summary: This study enhances the accuracy with which the aboveground biomass (AGB) of high‐AGB forests is estimated, and the results should be applicable to other subtropical forest regions. Using a machine learning approach to fuse multisource data, we propose to integrate spatial statistical analyses to identify critical cofactors, such as dominant tree species, canopy closure, and herbaceous plant cover. These factors are then incorporated into the analysis to further refine high‐AGB estimates. Applying these methods substantially improves the accuracy of high‐AGB estimates and is crucial in supporting forest management, conservation, and related policy development in subtropical regions. Key Points: Spatial statistical analysis identifies key auxiliary factors and refines estimates of high aboveground biomass (AGB)Incorporating the dominant auxiliary factors increases the accuracy of high‐AGB estimates in tropical forestsSpatial statistics analysis combined with the use of multisource data and machine learning allows for accurate estimates of high‐AGB regions [ABSTRACT FROM AUTHOR]

Forest disturbance threshold is defined as a critical disturbance level (e.g., % of forest cover change) in forested landscapes above which significant hydrological impacts are detected. Determining disturbance thresholds is critically important for supporting forest management to ensure the sustaining of ecological and hydrological functions. However, there are very few quantitative evaluations of forest disturbance thresholds globally. In this study, we applied a well‐tested methodology (the modified double mass curve) to derive the long‐term, continuous hydrological response curves and then to quantify forest disturbance thresholds on annual streamflow in 42 forested watersheds in British Columbia, Canada. The results show that forest disturbance thresholds for significant and cumulative hydrological impacts vary from 7% to 52% of cumulative equivalent clear‐cut area with an average of 17% or from 8% to 52% of disturbed area with an average of 19%. Climate (inter‐annual and intra‐annual) and watershed properties exert critical controls on forest disturbance thresholds. Watersheds with greater snowfall proportions (more annual precipitation falling as snow), more desynchronizations (temporal mismatching) of energy demand and water supply at the intra‐annual scale, less diverse ecosystems, and larger watershed sizes have lower forest disturbance thresholds. Given the present forest disturbance levels in the central interior of British Columbia, about half (53%) of the forested watersheds have already crossed the average disturbance threshold. These results highlight that watershed planning and management using forest disturbance thresholds must carefully consider local climate and watershed properties. The methodology can be effectively and robustly extended elsewhere around the globe. Plain Language Summary: This first‐ever study uses the hydrological response curves to quantify forest disturbance thresholds on annual streamflow in 42 forested watersheds in the interior of British Columbia, Canada. We find that forest disturbance thresholds range from 7% to 52% of cumulative equivalent clear‐cut area with the average of 17%. Climate and watershed properties play critical roles in controlling disturbance thresholds. Watersheds characterized by more annual precipitation falling as snow, more mismatching of energy and water at the intra‐annual scale, larger watershed size, and less diverse ecosystems exhibit lower disturbance thresholds. Management implications and future research needs for preserving hydrological functions are discussed. Key Points: A new approach with the hydrological response curves is used to quantify forest disturbance thresholdsForest disturbance thresholds for cumulative impacts on annual streamflow vary from 7% to 52% of cumulative equivalent clear‐cut area with the average of 17%Climate and watershed properties exert critical controls on the thresholds [ABSTRACT FROM AUTHOR]

In this paper,the design of a blade retractable vane pump was demonstrated. The combination of a vane pump with a plug-in type pilot-operated directional control valve can achieve the shift between the two states of oil supply and unloading of the vane pump. In addition,the damping effect of the directional valve makes it possible for the extension of the vane even in the high pressure portion. The axial clearance model was established to calculate the leakage power loss and the shear loss of the oil film. The relationship between the total power loss and the axial clearance was set up to obtain the optimal axial clearance.Furthermore,the condition of blade retraction under unloaded state was concluded and the temperature increase caused by oil film shear was calculated based on the theory of hot wedge oil film. Force exerted on the blade due to oil film expansion under the increased temperature was also verified. The conclusion of blade retraction condition during unloading of the vane pump enables the potential for future applications and further researches.

As one of the key transmitting components and wearing parts of scraper conveyor,There are different types of wear which result to the failure of flat type chains. This study focused on the failure of the flat chains of Joy scraper conveyor used in Shendong Coal Mining Group. 3 D scanner was used to acquire the surface details of both worn and unworn flat chains. The data were then used to reconstruct the solid 3 D models of these two parts. Software package CATIA was employed to compare the models,including the wear volumes,positions and quantitative analysis of wear. The results showed that wear is the main failure mode of flat chain,but flat ring and ring have different Wear and wear positions. It provides a reference for people who engaged in mining machinery for failure analysis and laser repair wear flat chain.

As drought and prolonged water stress become more prevalent in dry regions under climate change, understanding and preserving water resources has become the focal point of many conversations. Forest regeneration after deforestation or disturbance can lead to over-populated juvenile stands with high water demands and low water use efficiency. Forest thinning improves tree health, carbon storage, and water use while decreasing stand demands in arid and semi-arid regions. However, little is known about the impacts of over-population on seasonal variation in depth to water uptake nor the magnitude of the effect of growing season drought conditions on water availability, and existing reports are highly variable by climatic region, species, and thinning intensity. In this study, stable isotope ratios of hydrogen (δ2H) and oxygen (δ18O) in water collected from soil varying depths and from twigs of lodgepole pine (Pinus contorta) under different degrees of thinning (control: 27,000 stems per ha; moderately thinned: 4,500 stems per ha; heavily thinned: 1,100 stems per ha) over the growing season and analyzed using the MixSIAR Bayesian mixing model to calculate the relative contributions of different water sources in the Okanagan Valley in the interior of British Columbia, Canada. We found that lodgepole pine trees shift their depth to water uptake depending on water availability under drought conditions and rely more heavily on older precipitation events that percolate through the soil profile when shallow soil water becomes less accessible. Interestingly, forest thinning did not cause a significant change in depth to water uptake. Our results support other findings by indicating that although lodgepole pines are drought tolerant and have dimorphic root systems, they cannot shift from deep water sources when shallow water becomes more available at the end of the growing season. [ABSTRACT FROM AUTHOR]