In this paper,work was conducted to reveal electrical tree behaviors（initiation and propagation）of silicone rubber（SIR） under an impulse voltage with high temperature.Impulse frequencies ranging from 10 Hz to 1 k ...In this paper,work was conducted to reveal electrical tree behaviors（initiation and propagation）of silicone rubber（SIR） under an impulse voltage with high temperature.Impulse frequencies ranging from 10 Hz to 1 k Hz were applied and the temperature was controlled between 30 °C and 90 °C.Experimental results show that tree initiation voltage decreases with increasing pulse frequency,and the descending amplitude is different in different frequency bands.As the pulse frequency increases,more frequent partial discharges occur in the channel,increasing the tree growth rate and the final shape intensity.As for temperature,the initiation voltage decreases and the tree shape becomes denser as the temperature gets higher.Based on differential scanning calorimetry results,we believe that partial segment relaxation of SIR at high temperature leads to a decrease in the initiation voltage.However,the tree growth rate decreases with increasing temperature.Carbonization deposition in the channel under high temperature was observed under microscope and proven by Raman analysis.Different tree growth models considering tree channel characteristics are proposed.It is believed that increasing the conductivity in the tree channel restrains the partial discharge,holding back the tree growth at high temperature.展开更多
This paper presents a comprehensive analysis of the insulation breakdown phenomenon in epoxy resin insulation induced by the degradation of electrical trees,with reference to both domestic and international studies.It...This paper presents a comprehensive analysis of the insulation breakdown phenomenon in epoxy resin insulation induced by the degradation of electrical trees,with reference to both domestic and international studies.It elucidates the mechanisms of electrical tree initiation and degradation in epoxy resins by drawing on the theories of space charge accumulation and migration,local electric field formation,ultraviolet radiation,and mechanical stress chain breakage.The paper also discusses the operational conditions of the electrical equipment,detailing the effects of superimposed electric fields,temperature gradients,mechanical stresses,magnetic gradients,and humid environments on the insulation degradation of the epoxy resin.Furthermore,it summarizes the correlation between tree growth characteristics and charge transport behavior under the influence of multiple physical fields.To enhance the insulation performance of epoxy resins and ensure the safe and reliable operation of electrical equipment,methods to inhibit electrical tree formation are discussed.These methods include the regulation of the manufacturing process,inorganic doping,and the use of self-repairing materials.The inhibition mechanisms are analyzed at the molecular configuration level and microstructural scale,and from a macroscopic standpoint.This study aimed to provide recommendations for future research on the growth and suppression of electrical trees in epoxy resin based on the current state of knowledge.展开更多
When making assessments of forest resources,there is nearly ubiquitous interest in quantifying current status and trends in tree biomass and carbon stocks.While important at various spatial scales,typical estimations ...When making assessments of forest resources,there is nearly ubiquitous interest in quantifying current status and trends in tree biomass and carbon stocks.While important at various spatial scales,typical estimations pertinent to broad forest management and policy issues are conducted for large areas such as state,regional,and national perspectives.These assessments are usually accomplished using large-area forest inventory data collected by National Forest Inventory(NFI)programs.While NFI efforts commonly collect size data for individual trees,there is often limited information for tree seedlings,e.g.,frequency by species.To fully describe the tree population across the entire range of sizes present,this study proposes methods to predict individual seedling groundline diameter and height using models developed from trees having a diameter at breast height(DBH)less than 7.62 cm.These attributes are subsequently used for the prediction of seedling stem volume,total aboveground biomass,and carbon content.The results suggest a smooth transition in tree attributes as size increases to where direct measurement of individual trees and prediction of their volume,biomass,and carbon are implemented as part of standard inventory protocols.Analyses including the full spectrum of tree sizes show that seedlings contribute roughly 0.6%–0.7%of the total tree volume/mass.This additional suite of information provides opportunities for more holistic assessments across the full spectrum of the tree resource or for specialized subdomains that include the seedling component.展开更多
This study investigated biomass allocation in young stands of European beech(Fagus sylvatica L.)and Norway spruce(Picea abies(L.)Karst.)across 31 forest sites in the Western Carpathians,Slovakia.A total of 541 trees a...This study investigated biomass allocation in young stands of European beech(Fagus sylvatica L.)and Norway spruce(Picea abies(L.)Karst.)across 31 forest sites in the Western Carpathians,Slovakia.A total of 541 trees aged 2–10 years,originating from natural regeneration and planting,were destructively sampled to quantify biomass in four components:foliage,branches,stems,and roots.Generalized non-linear least squares(GNLS)models with a weighing variance function outperformed log-transformed seemingly unrelated regression(SUR)models in terms of accuracy and robustness,especially for foliage and branch biomass.When using height as the predictor,SUR models tended to underestimate biomass in planted beech,leading to notable underprediction of aboveground and total biomass.Biomass allocation patterns varied significantly by species and regeneration origin.Using a non-linear system of equations and component ratio modelling,we found out that planted spruce displayed low variability and a consistent dominance of needle biomass,while naturally regenerated beech showed greater variability and a higher proportion of stem biomass,reflecting stronger competition-driven vertical growth.Interspecific differences in total biomass were more pronounced when using tree height,with spruce generally exhibiting greater biomass than beech at equivalent heights.Overall,stem base diameter marginally outperformed tree height as a predictor of biomass.However,tree height-based models showed strong performance and are particularly suitable for integration with remote sensing applications.These findings can directly support forest managers and modellers in comparing regeneration methods and biomass estimation approaches for early-stage stand development,carbon accounting,and remote sensing calibration.展开更多
Bemisia tabaci is a complex of cryptic agro-economically important pest species characterized by diverse clades,substantial genetic diversity along with strong phylogeographic associations.However,a comprehensive phyl...Bemisia tabaci is a complex of cryptic agro-economically important pest species characterized by diverse clades,substantial genetic diversity along with strong phylogeographic associations.However,a comprehensive phylogenomic analysis across the entire complex has been lacking,we thus conducted phylogenomic analyses and explored biogeographic patterns using 680 single-copy nuclear genes(SCNs)obtained from whole-genome sequencing data of 58 globally sourced B.tabaci specimens.We constructed both concatenation and coalescent trees using 680 SCNs,which produced highly supported bootstrap values and nearly identical topologies for all major clades.When comparing these concatenation trees with those constructed using mitochondrial cytochrome oxidase I(mtCOI)and mitochondrial genome,we found conflicting phylogenetic relationships,with the later trees recovering fewer major clades.In a separate comparison between concatenation and coalescent trees,particularly those generated using IQ-TREE,they were found to delineate population relationships more effectively than RaxML.In contrast,coalescent phylogenies were proficient in elucidating geographical dispersal patterns and the reorganization of biological species.Furthermore,we provided a strict consensus tree that clearly defines relationships within most clades,laying a solid foundation for future research on the evolution and taxonomy of B.tabaci.Ancestral range estimates suggested that the ancestral region of the complex is likely situated in equatorial Africa,the Middle East,and Mediterranean regions.Subsequently,the expansion occurred into part of the Palearctic and further into the Nearctic,Neotropical,Indomalayan,and Australasian regions.These findings challenge both previous classifications and origin hypotheses,offering a notably more comprehensive understanding of the global distribution,evolutionary history,diversification,and biogeography of B.tabaci.展开更多
Allometric equations are fundamental tools in ecological research and forestry management,widely used for estimating above-ground biomass and production,serving as the core foundations of dynamic vegetation models.Usi...Allometric equations are fundamental tools in ecological research and forestry management,widely used for estimating above-ground biomass and production,serving as the core foundations of dynamic vegetation models.Using global datasets from Tallo(a tree allometry and crown architecture database encompassing thousands of species)and TRY(a plant traits database),we fit B ayesian hierarchical models with three alternative functional forms(powerlaw,generalized Michaelis-Menten(gMM),and Weibull)to characterize how diameter at breast height(DBH),tree height(H),and crown radius(CR)scale with and without wood density as a species-level predictor.Our analysis revealed that the saturating Weibull function best captured the relationship between tree height and DBH in both functional groups,whereas the CR-DBH relationship was best predicted by a power-law function in angiosperms and by the gMM function in gymnosperms.Although including wood density did not significantly improve predictive performance,it revealed important ecological trade-offs:lighter-wood angiosperms achieve taller mature heights more rapidly,and denser wood promotes wider crown expansion across clades.We also found that accurately estimating DBH required considering both height and crown size,highlighting how these variables together distinguish trees of similar height but differing trunk diameters.Our results emphasize the importance of applying saturating functions for large trees to improve forest biomass estimates and show that wood density,though not always predictive at broad scales,helps illuminate the biomechanical and ecological constraints underlying diverse tree architectures.These findings offer practical pathways for integrating height-and crown-based metrics into existing carbon monitoring programs worldwide.展开更多
Soil organic carbon in forest affects nutrient availability,microbial processes,and organic matter inputs.Dominant tree species have increasingly shifted from ectomycorrhizal to arbuscular mycorrhizal associations in ...Soil organic carbon in forest affects nutrient availability,microbial processes,and organic matter inputs.Dominant tree species have increasingly shifted from ectomycorrhizal to arbuscular mycorrhizal associations in subtropical forests.However,the consequences of this shift for soil organic carbon is poorly understood.To address this,a field study was conducted across a natural gradient of arbuscular tree associations to investigate how different mycorrhizal associations affect soil organic carbon quantity,composition,chemical stability,and related soil properties.Soil organic carbon fractions,functional groups,microbial enzyme activities were analyzed.Results showed that increasing arbuscular mycorrhizal dominance was associated with declines in total soil organic carbon,particularly in recalcitrant and aromatic carbon forms.Ectomycorrhizaldominated forests exhibited higher nitrogen availability and elevated nitrogen-hydrolyzing enzyme activity,suggesting enhanced nitrogen acquisition strategies that suppress soil organic carbon decomposition and promote carbon retention.These findings indicate that mycorrhizal-mediated shifts in tree composition may significantly alter soil carbon sequestration potential.Incorporating mycorrhizal functional traits into forest management and carbon modeling could improve predictions of soil organic carbon responses under future environmental change.展开更多
Drought has the potential to induce extensive defoliation in forest trees.However,the responses of non-structural carbohydrates(NSCs,including soluble sugar and starch)to the combined effects of drought and defoliatio...Drought has the potential to induce extensive defoliation in forest trees.However,the responses of non-structural carbohydrates(NSCs,including soluble sugar and starch)to the combined effects of drought and defoliation remain to be elucidated,particularly in pine trees.In this study,we investigated the interactive effects of drought and defoliation on the contents of NSCs in five organs(new and old needles,twigs,stems,as well as roots)of Chinese pine(Pinus tabuliformis)seedlings.We sampled two batches of the seedlings at 30 and 50 days,respectively.Our results showed that Chinese pine could tolerate mild drought,but severe drought significantly decreased the content of soluble sugars in all organs.Defoliation initially suppressed the photosynthetic rate and significantly reduced the soluble sugar content in all organs.However,after 50 days,this effect was substantially mitigated by the new needle growth.Starch content in twigs,stems,and roots was found to be more vulnerable to defoliation than to drought.A significant interactive effect existed between drought and defoliation on NSCs,with defoliation exacerbating the negative impact of drought on the accumulation of NSCs,especially in new needles and roots.These findings highlight the complex effects of defoliation on NSCs during drought,underscoring critical implications for the management and economic value of Chinese pine forests.展开更多
Background 3D botanical tree reconstruction from a single image plays a vital role in the field of computer graphics.However,accurately capturing the intricate branching patterns and detailed morphologies of trees rem...Background 3D botanical tree reconstruction from a single image plays a vital role in the field of computer graphics.However,accurately capturing the intricate branching patterns and detailed morphologies of trees remains a challenge.Methods In this study,we proposed a novel approach for single-image tree reconstruction using a conditional generative adversarial network to infer the 3D skeleton of a tree in the form of a 2D skeleton depth map.Based on the 2D skeleton depth map,a corresponding branching structure(3D skeleton)that inherits the tree shape in the input image and leaves can be generated using a procedural modeling technique.Result Experimental results show that the proposed method accurately reconstructs diverse tree structures across species.Both quantitative and qualitative evaluations demonstrate improved skeleton completeness,branching accuracy,and visual realism over baseline methods,while requiring no user input.Conclusions Our proposed approach for generating lifelike 3D tree models from a single image with no user input shows its proficiency in achieving efficient and reliable reconstruction.These results showcase the capability of the proposed model to recreate complex tree architectures while capturing their visual authenticity.展开更多
The goal of this study was to determine the spatiotemporal characteristics of mangrove distribution and fragmentation patterns from 1988 through 2019 in Dongzhaigang.Land cover datasets were generated for Dongzhaigang...The goal of this study was to determine the spatiotemporal characteristics of mangrove distribution and fragmentation patterns from 1988 through 2019 in Dongzhaigang.Land cover datasets were generated for Dongzhaigang for multiple years via a decision tree method based on a classification and regression tree(CART)algorithm using Landsat time series images.Spatiotemporal transform and fragmentation patterns of mangrove distribution were separately assessed with a transfer matrix of land cover types and a landscape pattern index.The classification method combined with multi-band images showed good accuracy,with overall accuracy higher than 90%.Mangrove areas in 1988,1999,2009,and 2019 were 2050,1875,1818,and 1750 ha,respectively,with decreases mainly due to conversion to aquaculture ponds and farmland.A mangrove growth index(MGI)was proposed,reflecting the water-mangrove relationship,showing positive mangrove growth from 1988–2009 and negative growth from 2009–2019.Study results indicated anthropogenic factors play a leading role in the extent and scale of mangrove effects over the past 30 years.According to the analysis results,corresponding management and protection measures are proposed to provide reference for the sustainable development of Dongzhaigang Mangrove Wetland ecosystem.展开更多
Peri-urban plantations in the Mediterranean are often degraded due to human inactivity and climate change,leading to a loss of ecosystem services and biodiversity.This study investigates the impact of different thinni...Peri-urban plantations in the Mediterranean are often degraded due to human inactivity and climate change,leading to a loss of ecosystem services and biodiversity.This study investigates the impact of different thinning practices on carbon sequestration and tree stability in a degraded periurban plantation in the Italian Apennines,six years after thinning.Three treatments were compared:(a)moderate thinning from below(-25%biomass),representing the typical practice;(b)intense selective thinning(-35%biomass),representing an innovative approach;and(c)no management as the control.Growth projections were used to estimate carbon recovery for these treatments,based on site-specific models calibrated with real data.The results show that both thinning approaches increased carbon sequestration over time,with the innovative thinning achieving a 7%higher annual carbon sequestration rate than traditional thinning and 8%more than the control.Estimated payback times were9 years for recovering the harvested volume in both thinning approaches,10 years for innovative thinning to surpass traditional thinning,17 years for innovative thinning to surpass the control,and 24 years for traditional thinning to surpass the control.Additionally,tree mechanical stability improved significantly in both thinning treatments after two years,with further increases observed in the innovative thinning group after six years.These results suggest that selective thinning can accelerate forest recovery and carbon sequestration,especially in areas with high stem density,where it can reduce the negative impacts of tree mortality and deadwood accumulation.However,careful planning is required to mitigate potential short-term stability is sues,particularly in challenging environments(e.g.,windy conditions,steep slopes).Forest management strategies should therefore aim to balance growth,carbon storage,and tree stability,considering both long-term sustainability and local environmental conditions.The findings are particularly relevant for current climate change mitigation strategies,emphasizing that thinning should be carefully tailored to forest type and conditions to maximize benefits in carbon credit generation and sustainable forest management practices.展开更多
This paper investigates the reliability of internal marine combustion engines using an integrated approach that combines Fault Tree Analysis(FTA)and Bayesian Networks(BN).FTA provides a structured,top-down method for ...This paper investigates the reliability of internal marine combustion engines using an integrated approach that combines Fault Tree Analysis(FTA)and Bayesian Networks(BN).FTA provides a structured,top-down method for identifying critical failure modes and their root causes,while BN introduces flexibility in probabilistic reasoning,enabling dynamic updates based on new evidence.This dual methodology overcomes the limitations of static FTA models,offering a comprehensive framework for system reliability analysis.Critical failures,including External Leakage(ELU),Failure to Start(FTS),and Overheating(OHE),were identified as key risks.By incorporating redundancy into high-risk components such as pumps and batteries,the likelihood of these failures was significantly reduced.For instance,redundant pumps reduced the probability of ELU by 31.88%,while additional batteries decreased the occurrence of FTS by 36.45%.The results underscore the practical benefits of combining FTA and BN for enhancing system reliability,particularly in maritime applications where operational safety and efficiency are critical.This research provides valuable insights for maintenance planning and highlights the importance of redundancy in critical systems,especially as the industry transitions toward more autonomous vessels.展开更多
Old-growth forests uniquely support biodiversity while serving as some of the planet's most important carbon stocks.The influence of tree and stand age on carbon flux dynamics remains debated—an urgent question a...Old-growth forests uniquely support biodiversity while serving as some of the planet's most important carbon stocks.The influence of tree and stand age on carbon flux dynamics remains debated—an urgent question as climate-driven disturbances may reshape forest age structures and in situ carbon storage.To clarify these relationships in Fagus sylvatica,systems,we examined a unique dataset of 3,503 tree ring series from 190 plots across some of the best preserved old-growth forests from five southern European countries.By employing a dendrochronological approach and integrating key environmental variables,including elevation,slope,temperature,and the presence of large-diameter trees(≥60 cm),we analyzed the complex relationships between tree/stand age within a plot(represented by plot-level mean values,hereafter“stand age”)and aboveground carbon stock across live,standing,and lying deadwood pools.The average stand age was 220 years,with 230 tC⋅ha^(-1) of carbon stored in aboveground biomass and necromass.We found a positive correlation between age and carbon storage at both the individual tree and plot levels.Notably,the presence of large-diameter trees was the strongest indicator of carbon stock,with carbon accumulation peaking at about 30%large-tree stems proportion before stabilising,while younger beech trees(below 100 years old)had a smaller contribution to carbon storage.We found no evidence of a decline in carbon stock with advancing stand age across the studied sites.Despite the ecological importance of old-growth forests,many of them remain unprotected and are disappearing across Europe.Our findings highlight the importance of preserving old-growth forests to maximize their role as long-term ecosystem carbon reservoirs.展开更多
Tree growth variability is a key determinant of forest stabilities.Previous studies have shown that recent climate change has increased variability in tree growth,while others have challenged this viewpoint,leading to...Tree growth variability is a key determinant of forest stabilities.Previous studies have shown that recent climate change has increased variability in tree growth,while others have challenged this viewpoint,leading to ongoing debate in this field.Moreover,gaps remain in understanding the climatic mechanisms driving increased tree growth variability,particularly for species simultaneously limited by multiple climate factors.In this study,we assessed the temporal trends in variability of Picea purpurea radial growth and its linkage with growth-climate sensitivity utilizing dendrochronological methods.Our results revealed a significant increase in P.purpurea radial growth variability from 1960 to 2020,as indicated by continuous rises in the standard deviation,coefficient of variation,and mean sensitivity of tree-ring width indices.The increased frequency of extreme growth declines further supported this finding.Furthermore,moisture condition in July was identified as a key limiting factor of P.purpurea growth.Notably,the strengthening relationship between tree-ring width indices and vapor pressure deficit(VPD)suggests that the moisture sensitivity for P.purpurea growth has increased over the period 1960-2020.This enhanced sensitivity to VPD,whose interannual variability has also increased synchronously,may have contributed to the rise in P.purpurea growth variability.Additionally,the maximum temperature in May was positively correlated with P.purpurea growth;however,there is little evidence that this factor contributed to the observed increase in growth variability.These findings provide new insights into P.purpurea growth trends and improve our understanding of the potential future impacts of climate change on forest ecosystems.展开更多
With the expanding applications of unmanned aerial vehicles(UAVs),precise flight evaluation has emerged as a critical enabler for efficient path planning,directly impacting operational performance and safety.Tradition...With the expanding applications of unmanned aerial vehicles(UAVs),precise flight evaluation has emerged as a critical enabler for efficient path planning,directly impacting operational performance and safety.Traditional path planning algorithms typically combine Dubins curves with local optimization to minimize trajectory length under 3D spatial constraints.However,these methods often overlook the correlation between pilot control quality and UAV flight dynamics,limiting their adaptability in complex scenarios.In this paper,we propose an intelligent flight evaluation model specifically designed to enhancemulti-waypoint trajectory optimization algorithms.Our model leverages a decision tree to integrate attitude parameters and trajectory matching metrics,establishing a quantitative link between pilot control quality and UAV flight states.Experimental results demonstrate that the proposed model not only accurately assesses pilot performance across diverse skill levels but also improves the optimality of generated trajectories.When integrated with our path planning algorithm,it efficiently produces optimal trajectories while strictly adhering to UAV flight constraints.This integrated framework highlights significant potential for real-time UAV training,performance assessment,and adaptive mission planning applications.展开更多
Tree failure is an international problem,a major risk to public safety,and of growing concern because of extreme weather events.Tree biomechanics can inform the probability of tree failure,but empirical data from trop...Tree failure is an international problem,a major risk to public safety,and of growing concern because of extreme weather events.Tree biomechanics can inform the probability of tree failure,but empirical data from tropical settings are scarce.As a case study,we analyze the biomechanics(safety factor)of large heritage trees in public spaces in Indonesia.We examined critical buckling height using the Euler and Ylinen bending stress method.Tree morphometry(height,diameter at breast height,crown diameter),stability(modulus of elasticity),critical buckling height,and safety factor were quantified during this study.We found that large heritage trees in public spaces with buttresses have taller and larger morphometry and higher trunk and crown weights than small trees without buttresses.These trees are highly stable against external pressure.The presence of buttresses protects the target tree from rain and wind,resulting in a higher critical buckling height(H_(cr))of large(58.9 m)and buttressed target trees(58.8)than small(33.5 m)and unbuttressed trees(42.6 m),and a safety factor level of 68%safer.We make recommendations for selecting and managing trees in public spaces in a way that(i)can enhance wellbeing and biodiversity in urban planning,and(ii)is informed by risk to public safety.展开更多
Delayed wound healing following radical gastrectomy remains an important yet underappreciated complication that prolongs hospitalization,increases costs,and undermines patient recovery.In An et al’s recent study,the ...Delayed wound healing following radical gastrectomy remains an important yet underappreciated complication that prolongs hospitalization,increases costs,and undermines patient recovery.In An et al’s recent study,the authors present a machine learning-based risk prediction approach using routinely available clinical and laboratory parameters.Among the evaluated algorithms,a decision tree model demonstrated excellent discrimination,achieving an area under the curve of 0.951 in the validation set and notably identifying all true cases of delayed wound healing at the Youden index threshold.The inclusion of variables such as drainage duration,preoperative white blood cell and neutrophil counts,alongside age and sex,highlights the pragmatic appeal of the model for early postoperative monitoring.Nevertheless,several aspects warrant critical reflection,including the reliance on a postoperative variable(drainage duration),internal validation only,and certain reporting inconsistencies.This letter underscores both the promise and the limitations of adopting interpretable machine learning models in perioperative care.We advocate for transparent reporting,external validation,and careful consideration of clinically actionable timepoints before integration into practice.Ultimately,this work represents a valuable step toward precision risk stratification in gastric cancer surgery,and sets the stage for multicenter,prospective evaluations.展开更多
[Objectives]To analyze the microbial community structure and diversity in the rhizosphere soil of peach trees in the Tangshan area of Hebei Province,identify the dominant microbial groups,and explore their potential e...[Objectives]To analyze the microbial community structure and diversity in the rhizosphere soil of peach trees in the Tangshan area of Hebei Province,identify the dominant microbial groups,and explore their potential ecological functions.[Methods]Amplification sequencing analysis of bacterial and fungal communities in the rhizosphere soil of a peach orchard in Qian'an County,Tangshan City,Hebei Province,was performed using Illumina MiSeq high-throughput sequencing technology.[Results]The indices of Sobs,Chao,ACE,and Shannon for soil bacteria in the rhizosphere soil of peach trees were all higher than those for fungi,indicating a more uniform and diverse bacterial community structure.At the phylum level,the bacteria with relatively high abundance included Pseudomonadota(28.29%),Acidobacteriota(18.10%),Bacillota(12.17%),and Actinomycetota(11.73%).In contrast,the fungi with relatively high abundance were Ascomycota(64.64%),Basidiomycota(14.22%),and Mortierellomycota(14.09%).At the genus level,the bacteria with relatively high abundance comprised Sphingomonas(5.00%),Priestia(3.38%),Nitrospira(2.05%),etc.The fungi with relatively high abundance included Fusarium(13.13%),Mortierella(12.86%),Tausonia(6.97%),Neocosmospora(4.77%),etc.[Conclusions]This study offers a foundational dataset and theoretical reference for the regulation of rhizosphere microecology and the management of soil health in peach orchards in Tangshan.展开更多
基金supported in part by National Basic Research Program of China(973 Project)(No.2014CB239501)National Natural Science Foundation of China(Nos.51707100,51377089)+1 种基金State Key Laboratory of Electrical Insulation and Power Equipment(No.EIPE16208)China Postdoctoral Science Foundation(No.2016M591176)
文摘In this paper,work was conducted to reveal electrical tree behaviors（initiation and propagation）of silicone rubber（SIR） under an impulse voltage with high temperature.Impulse frequencies ranging from 10 Hz to 1 k Hz were applied and the temperature was controlled between 30 °C and 90 °C.Experimental results show that tree initiation voltage decreases with increasing pulse frequency,and the descending amplitude is different in different frequency bands.As the pulse frequency increases,more frequent partial discharges occur in the channel,increasing the tree growth rate and the final shape intensity.As for temperature,the initiation voltage decreases and the tree shape becomes denser as the temperature gets higher.Based on differential scanning calorimetry results,we believe that partial segment relaxation of SIR at high temperature leads to a decrease in the initiation voltage.However,the tree growth rate decreases with increasing temperature.Carbonization deposition in the channel under high temperature was observed under microscope and proven by Raman analysis.Different tree growth models considering tree channel characteristics are proposed.It is believed that increasing the conductivity in the tree channel restrains the partial discharge,holding back the tree growth at high temperature.
基金Supported by the Smart Gird-National Science and Technology Major Project(2024ZD0802401)the National Natural Science Foundation of China(52307181,52220105002).
文摘This paper presents a comprehensive analysis of the insulation breakdown phenomenon in epoxy resin insulation induced by the degradation of electrical trees,with reference to both domestic and international studies.It elucidates the mechanisms of electrical tree initiation and degradation in epoxy resins by drawing on the theories of space charge accumulation and migration,local electric field formation,ultraviolet radiation,and mechanical stress chain breakage.The paper also discusses the operational conditions of the electrical equipment,detailing the effects of superimposed electric fields,temperature gradients,mechanical stresses,magnetic gradients,and humid environments on the insulation degradation of the epoxy resin.Furthermore,it summarizes the correlation between tree growth characteristics and charge transport behavior under the influence of multiple physical fields.To enhance the insulation performance of epoxy resins and ensure the safe and reliable operation of electrical equipment,methods to inhibit electrical tree formation are discussed.These methods include the regulation of the manufacturing process,inorganic doping,and the use of self-repairing materials.The inhibition mechanisms are analyzed at the molecular configuration level and microstructural scale,and from a macroscopic standpoint.This study aimed to provide recommendations for future research on the growth and suppression of electrical trees in epoxy resin based on the current state of knowledge.
文摘When making assessments of forest resources,there is nearly ubiquitous interest in quantifying current status and trends in tree biomass and carbon stocks.While important at various spatial scales,typical estimations pertinent to broad forest management and policy issues are conducted for large areas such as state,regional,and national perspectives.These assessments are usually accomplished using large-area forest inventory data collected by National Forest Inventory(NFI)programs.While NFI efforts commonly collect size data for individual trees,there is often limited information for tree seedlings,e.g.,frequency by species.To fully describe the tree population across the entire range of sizes present,this study proposes methods to predict individual seedling groundline diameter and height using models developed from trees having a diameter at breast height(DBH)less than 7.62 cm.These attributes are subsequently used for the prediction of seedling stem volume,total aboveground biomass,and carbon content.The results suggest a smooth transition in tree attributes as size increases to where direct measurement of individual trees and prediction of their volume,biomass,and carbon are implemented as part of standard inventory protocols.Analyses including the full spectrum of tree sizes show that seedlings contribute roughly 0.6%–0.7%of the total tree volume/mass.This additional suite of information provides opportunities for more holistic assessments across the full spectrum of the tree resource or for specialized subdomains that include the seedling component.
基金funded by the grant“EVA4.0”,No.Z.02.1.01/0.0/0.0/16_019/0000803 supported by OP RDE as well as by the projects APVV-19-0387,APVV-22-0056,and APVV-23-0293 from the Slovak Research and Development Agencyco-funded by the European Commission under the Horizon Europe Teaming for Excellence action+1 种基金project Ligno Silvagrant agreement No.101059552。
文摘This study investigated biomass allocation in young stands of European beech(Fagus sylvatica L.)and Norway spruce(Picea abies(L.)Karst.)across 31 forest sites in the Western Carpathians,Slovakia.A total of 541 trees aged 2–10 years,originating from natural regeneration and planting,were destructively sampled to quantify biomass in four components:foliage,branches,stems,and roots.Generalized non-linear least squares(GNLS)models with a weighing variance function outperformed log-transformed seemingly unrelated regression(SUR)models in terms of accuracy and robustness,especially for foliage and branch biomass.When using height as the predictor,SUR models tended to underestimate biomass in planted beech,leading to notable underprediction of aboveground and total biomass.Biomass allocation patterns varied significantly by species and regeneration origin.Using a non-linear system of equations and component ratio modelling,we found out that planted spruce displayed low variability and a consistent dominance of needle biomass,while naturally regenerated beech showed greater variability and a higher proportion of stem biomass,reflecting stronger competition-driven vertical growth.Interspecific differences in total biomass were more pronounced when using tree height,with spruce generally exhibiting greater biomass than beech at equivalent heights.Overall,stem base diameter marginally outperformed tree height as a predictor of biomass.However,tree height-based models showed strong performance and are particularly suitable for integration with remote sensing applications.These findings can directly support forest managers and modellers in comparing regeneration methods and biomass estimation approaches for early-stage stand development,carbon accounting,and remote sensing calibration.
基金supported by the Bill&Melinda Gates Foundation(African cassava whitefly project,OPP1058938)the National Natural Science Foundation of China(Grant numbers 31501878).
文摘Bemisia tabaci is a complex of cryptic agro-economically important pest species characterized by diverse clades,substantial genetic diversity along with strong phylogeographic associations.However,a comprehensive phylogenomic analysis across the entire complex has been lacking,we thus conducted phylogenomic analyses and explored biogeographic patterns using 680 single-copy nuclear genes(SCNs)obtained from whole-genome sequencing data of 58 globally sourced B.tabaci specimens.We constructed both concatenation and coalescent trees using 680 SCNs,which produced highly supported bootstrap values and nearly identical topologies for all major clades.When comparing these concatenation trees with those constructed using mitochondrial cytochrome oxidase I(mtCOI)and mitochondrial genome,we found conflicting phylogenetic relationships,with the later trees recovering fewer major clades.In a separate comparison between concatenation and coalescent trees,particularly those generated using IQ-TREE,they were found to delineate population relationships more effectively than RaxML.In contrast,coalescent phylogenies were proficient in elucidating geographical dispersal patterns and the reorganization of biological species.Furthermore,we provided a strict consensus tree that clearly defines relationships within most clades,laying a solid foundation for future research on the evolution and taxonomy of B.tabaci.Ancestral range estimates suggested that the ancestral region of the complex is likely situated in equatorial Africa,the Middle East,and Mediterranean regions.Subsequently,the expansion occurred into part of the Palearctic and further into the Nearctic,Neotropical,Indomalayan,and Australasian regions.These findings challenge both previous classifications and origin hypotheses,offering a notably more comprehensive understanding of the global distribution,evolutionary history,diversification,and biogeography of B.tabaci.
基金supported by the Xingdian Talent Support Program of Yunnan Province(E5YNR03B01)the Xishuangbanna State Rainforest Talent Support Program(E4BN041B01)the CAS President’s International Fellowship Initiative(2020FYB0003)。
文摘Allometric equations are fundamental tools in ecological research and forestry management,widely used for estimating above-ground biomass and production,serving as the core foundations of dynamic vegetation models.Using global datasets from Tallo(a tree allometry and crown architecture database encompassing thousands of species)and TRY(a plant traits database),we fit B ayesian hierarchical models with three alternative functional forms(powerlaw,generalized Michaelis-Menten(gMM),and Weibull)to characterize how diameter at breast height(DBH),tree height(H),and crown radius(CR)scale with and without wood density as a species-level predictor.Our analysis revealed that the saturating Weibull function best captured the relationship between tree height and DBH in both functional groups,whereas the CR-DBH relationship was best predicted by a power-law function in angiosperms and by the gMM function in gymnosperms.Although including wood density did not significantly improve predictive performance,it revealed important ecological trade-offs:lighter-wood angiosperms achieve taller mature heights more rapidly,and denser wood promotes wider crown expansion across clades.We also found that accurately estimating DBH required considering both height and crown size,highlighting how these variables together distinguish trees of similar height but differing trunk diameters.Our results emphasize the importance of applying saturating functions for large trees to improve forest biomass estimates and show that wood density,though not always predictive at broad scales,helps illuminate the biomechanical and ecological constraints underlying diverse tree architectures.These findings offer practical pathways for integrating height-and crown-based metrics into existing carbon monitoring programs worldwide.
基金supported by the National Natural Science Foundation of China(grant numbers 32471851,32171759 and 32201533)Jiangxi Province Ganpo Juncai Support Plan(2024BCE50043).
文摘Soil organic carbon in forest affects nutrient availability,microbial processes,and organic matter inputs.Dominant tree species have increasingly shifted from ectomycorrhizal to arbuscular mycorrhizal associations in subtropical forests.However,the consequences of this shift for soil organic carbon is poorly understood.To address this,a field study was conducted across a natural gradient of arbuscular tree associations to investigate how different mycorrhizal associations affect soil organic carbon quantity,composition,chemical stability,and related soil properties.Soil organic carbon fractions,functional groups,microbial enzyme activities were analyzed.Results showed that increasing arbuscular mycorrhizal dominance was associated with declines in total soil organic carbon,particularly in recalcitrant and aromatic carbon forms.Ectomycorrhizaldominated forests exhibited higher nitrogen availability and elevated nitrogen-hydrolyzing enzyme activity,suggesting enhanced nitrogen acquisition strategies that suppress soil organic carbon decomposition and promote carbon retention.These findings indicate that mycorrhizal-mediated shifts in tree composition may significantly alter soil carbon sequestration potential.Incorporating mycorrhizal functional traits into forest management and carbon modeling could improve predictions of soil organic carbon responses under future environmental change.
基金funded by the National Natural Science Foundation of China(42201064,32301381)the Joint Fund for Regional Innovation and Development of the National Science Foundation(U22A20570)+1 种基金the Science and Technology Innovation Program of Hunan Province of China(2022RC4027)Natural Science Foundation of Hunan Province of China(2023JJ40440).
文摘Drought has the potential to induce extensive defoliation in forest trees.However,the responses of non-structural carbohydrates(NSCs,including soluble sugar and starch)to the combined effects of drought and defoliation remain to be elucidated,particularly in pine trees.In this study,we investigated the interactive effects of drought and defoliation on the contents of NSCs in five organs(new and old needles,twigs,stems,as well as roots)of Chinese pine(Pinus tabuliformis)seedlings.We sampled two batches of the seedlings at 30 and 50 days,respectively.Our results showed that Chinese pine could tolerate mild drought,but severe drought significantly decreased the content of soluble sugars in all organs.Defoliation initially suppressed the photosynthetic rate and significantly reduced the soluble sugar content in all organs.However,after 50 days,this effect was substantially mitigated by the new needle growth.Starch content in twigs,stems,and roots was found to be more vulnerable to defoliation than to drought.A significant interactive effect existed between drought and defoliation on NSCs,with defoliation exacerbating the negative impact of drought on the accumulation of NSCs,especially in new needles and roots.These findings highlight the complex effects of defoliation on NSCs during drought,underscoring critical implications for the management and economic value of Chinese pine forests.
文摘Background 3D botanical tree reconstruction from a single image plays a vital role in the field of computer graphics.However,accurately capturing the intricate branching patterns and detailed morphologies of trees remains a challenge.Methods In this study,we proposed a novel approach for single-image tree reconstruction using a conditional generative adversarial network to infer the 3D skeleton of a tree in the form of a 2D skeleton depth map.Based on the 2D skeleton depth map,a corresponding branching structure(3D skeleton)that inherits the tree shape in the input image and leaves can be generated using a procedural modeling technique.Result Experimental results show that the proposed method accurately reconstructs diverse tree structures across species.Both quantitative and qualitative evaluations demonstrate improved skeleton completeness,branching accuracy,and visual realism over baseline methods,while requiring no user input.Conclusions Our proposed approach for generating lifelike 3D tree models from a single image with no user input shows its proficiency in achieving efficient and reliable reconstruction.These results showcase the capability of the proposed model to recreate complex tree architectures while capturing their visual authenticity.
基金financially supported by the National Natural Science Foundation of China(Nos.U2244225 and 42020104005)the Ministry of Education of China(111 Project)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)and China Geological Survey(No.DD20211391)。
文摘The goal of this study was to determine the spatiotemporal characteristics of mangrove distribution and fragmentation patterns from 1988 through 2019 in Dongzhaigang.Land cover datasets were generated for Dongzhaigang for multiple years via a decision tree method based on a classification and regression tree(CART)algorithm using Landsat time series images.Spatiotemporal transform and fragmentation patterns of mangrove distribution were separately assessed with a transfer matrix of land cover types and a landscape pattern index.The classification method combined with multi-band images showed good accuracy,with overall accuracy higher than 90%.Mangrove areas in 1988,1999,2009,and 2019 were 2050,1875,1818,and 1750 ha,respectively,with decreases mainly due to conversion to aquaculture ponds and farmland.A mangrove growth index(MGI)was proposed,reflecting the water-mangrove relationship,showing positive mangrove growth from 1988–2009 and negative growth from 2009–2019.Study results indicated anthropogenic factors play a leading role in the extent and scale of mangrove effects over the past 30 years.According to the analysis results,corresponding management and protection measures are proposed to provide reference for the sustainable development of Dongzhaigang Mangrove Wetland ecosystem.
基金supported initially by the LIFE FoResMit Project(LIFE14 CCM/IT/000905)。
文摘Peri-urban plantations in the Mediterranean are often degraded due to human inactivity and climate change,leading to a loss of ecosystem services and biodiversity.This study investigates the impact of different thinning practices on carbon sequestration and tree stability in a degraded periurban plantation in the Italian Apennines,six years after thinning.Three treatments were compared:(a)moderate thinning from below(-25%biomass),representing the typical practice;(b)intense selective thinning(-35%biomass),representing an innovative approach;and(c)no management as the control.Growth projections were used to estimate carbon recovery for these treatments,based on site-specific models calibrated with real data.The results show that both thinning approaches increased carbon sequestration over time,with the innovative thinning achieving a 7%higher annual carbon sequestration rate than traditional thinning and 8%more than the control.Estimated payback times were9 years for recovering the harvested volume in both thinning approaches,10 years for innovative thinning to surpass traditional thinning,17 years for innovative thinning to surpass the control,and 24 years for traditional thinning to surpass the control.Additionally,tree mechanical stability improved significantly in both thinning treatments after two years,with further increases observed in the innovative thinning group after six years.These results suggest that selective thinning can accelerate forest recovery and carbon sequestration,especially in areas with high stem density,where it can reduce the negative impacts of tree mortality and deadwood accumulation.However,careful planning is required to mitigate potential short-term stability is sues,particularly in challenging environments(e.g.,windy conditions,steep slopes).Forest management strategies should therefore aim to balance growth,carbon storage,and tree stability,considering both long-term sustainability and local environmental conditions.The findings are particularly relevant for current climate change mitigation strategies,emphasizing that thinning should be carefully tailored to forest type and conditions to maximize benefits in carbon credit generation and sustainable forest management practices.
基金supported by Istanbul Technical University(Project No.45698)supported through the“Young Researchers’Career Development Project-training of doctoral students”of the Croatian Science Foundation.
文摘This paper investigates the reliability of internal marine combustion engines using an integrated approach that combines Fault Tree Analysis(FTA)and Bayesian Networks(BN).FTA provides a structured,top-down method for identifying critical failure modes and their root causes,while BN introduces flexibility in probabilistic reasoning,enabling dynamic updates based on new evidence.This dual methodology overcomes the limitations of static FTA models,offering a comprehensive framework for system reliability analysis.Critical failures,including External Leakage(ELU),Failure to Start(FTS),and Overheating(OHE),were identified as key risks.By incorporating redundancy into high-risk components such as pumps and batteries,the likelihood of these failures was significantly reduced.For instance,redundant pumps reduced the probability of ELU by 31.88%,while additional batteries decreased the occurrence of FTS by 36.45%.The results underscore the practical benefits of combining FTA and BN for enhancing system reliability,particularly in maritime applications where operational safety and efficiency are critical.This research provides valuable insights for maintenance planning and highlights the importance of redundancy in critical systems,especially as the industry transitions toward more autonomous vessels.
基金supported by the Czech University of Life Sciences(Internal Grant Agency:A_12_24,43110/1312/3103)the Czech Science Foundation(Grant GACR No.21-27454S)+3 种基金Technology Agency of the Czech Republic(TACR No.SS06010420)provided by the CLIMB-FOREST project(No.101060554)project FORbEST(No.101181878)funded under the Horizon Europe Framework Programme。
文摘Old-growth forests uniquely support biodiversity while serving as some of the planet's most important carbon stocks.The influence of tree and stand age on carbon flux dynamics remains debated—an urgent question as climate-driven disturbances may reshape forest age structures and in situ carbon storage.To clarify these relationships in Fagus sylvatica,systems,we examined a unique dataset of 3,503 tree ring series from 190 plots across some of the best preserved old-growth forests from five southern European countries.By employing a dendrochronological approach and integrating key environmental variables,including elevation,slope,temperature,and the presence of large-diameter trees(≥60 cm),we analyzed the complex relationships between tree/stand age within a plot(represented by plot-level mean values,hereafter“stand age”)and aboveground carbon stock across live,standing,and lying deadwood pools.The average stand age was 220 years,with 230 tC⋅ha^(-1) of carbon stored in aboveground biomass and necromass.We found a positive correlation between age and carbon storage at both the individual tree and plot levels.Notably,the presence of large-diameter trees was the strongest indicator of carbon stock,with carbon accumulation peaking at about 30%large-tree stems proportion before stabilising,while younger beech trees(below 100 years old)had a smaller contribution to carbon storage.We found no evidence of a decline in carbon stock with advancing stand age across the studied sites.Despite the ecological importance of old-growth forests,many of them remain unprotected and are disappearing across Europe.Our findings highlight the importance of preserving old-growth forests to maximize their role as long-term ecosystem carbon reservoirs.
基金funded by the Science and Technology Program of Gansu Province(25JRRA487)the National Natural Science Foundation of China(42101072)the Key Research and Development Program of Gansu Province(22YF7FA029).
文摘Tree growth variability is a key determinant of forest stabilities.Previous studies have shown that recent climate change has increased variability in tree growth,while others have challenged this viewpoint,leading to ongoing debate in this field.Moreover,gaps remain in understanding the climatic mechanisms driving increased tree growth variability,particularly for species simultaneously limited by multiple climate factors.In this study,we assessed the temporal trends in variability of Picea purpurea radial growth and its linkage with growth-climate sensitivity utilizing dendrochronological methods.Our results revealed a significant increase in P.purpurea radial growth variability from 1960 to 2020,as indicated by continuous rises in the standard deviation,coefficient of variation,and mean sensitivity of tree-ring width indices.The increased frequency of extreme growth declines further supported this finding.Furthermore,moisture condition in July was identified as a key limiting factor of P.purpurea growth.Notably,the strengthening relationship between tree-ring width indices and vapor pressure deficit(VPD)suggests that the moisture sensitivity for P.purpurea growth has increased over the period 1960-2020.This enhanced sensitivity to VPD,whose interannual variability has also increased synchronously,may have contributed to the rise in P.purpurea growth variability.Additionally,the maximum temperature in May was positively correlated with P.purpurea growth;however,there is little evidence that this factor contributed to the observed increase in growth variability.These findings provide new insights into P.purpurea growth trends and improve our understanding of the potential future impacts of climate change on forest ecosystems.
基金funded in part by the Fundamental Research Funds for the Central Universities under Grant NS2023052in part by the Natural Science Foundation of Jiangsu Province of China under Grants No.BK20231439 and No.BK20222012.
文摘With the expanding applications of unmanned aerial vehicles(UAVs),precise flight evaluation has emerged as a critical enabler for efficient path planning,directly impacting operational performance and safety.Traditional path planning algorithms typically combine Dubins curves with local optimization to minimize trajectory length under 3D spatial constraints.However,these methods often overlook the correlation between pilot control quality and UAV flight dynamics,limiting their adaptability in complex scenarios.In this paper,we propose an intelligent flight evaluation model specifically designed to enhancemulti-waypoint trajectory optimization algorithms.Our model leverages a decision tree to integrate attitude parameters and trajectory matching metrics,establishing a quantitative link between pilot control quality and UAV flight states.Experimental results demonstrate that the proposed model not only accurately assesses pilot performance across diverse skill levels but also improves the optimality of generated trajectories.When integrated with our path planning algorithm,it efficiently produces optimal trajectories while strictly adhering to UAV flight constraints.This integrated framework highlights significant potential for real-time UAV training,performance assessment,and adaptive mission planning applications.
文摘Tree failure is an international problem,a major risk to public safety,and of growing concern because of extreme weather events.Tree biomechanics can inform the probability of tree failure,but empirical data from tropical settings are scarce.As a case study,we analyze the biomechanics(safety factor)of large heritage trees in public spaces in Indonesia.We examined critical buckling height using the Euler and Ylinen bending stress method.Tree morphometry(height,diameter at breast height,crown diameter),stability(modulus of elasticity),critical buckling height,and safety factor were quantified during this study.We found that large heritage trees in public spaces with buttresses have taller and larger morphometry and higher trunk and crown weights than small trees without buttresses.These trees are highly stable against external pressure.The presence of buttresses protects the target tree from rain and wind,resulting in a higher critical buckling height(H_(cr))of large(58.9 m)and buttressed target trees(58.8)than small(33.5 m)and unbuttressed trees(42.6 m),and a safety factor level of 68%safer.We make recommendations for selecting and managing trees in public spaces in a way that(i)can enhance wellbeing and biodiversity in urban planning,and(ii)is informed by risk to public safety.
文摘Delayed wound healing following radical gastrectomy remains an important yet underappreciated complication that prolongs hospitalization,increases costs,and undermines patient recovery.In An et al’s recent study,the authors present a machine learning-based risk prediction approach using routinely available clinical and laboratory parameters.Among the evaluated algorithms,a decision tree model demonstrated excellent discrimination,achieving an area under the curve of 0.951 in the validation set and notably identifying all true cases of delayed wound healing at the Youden index threshold.The inclusion of variables such as drainage duration,preoperative white blood cell and neutrophil counts,alongside age and sex,highlights the pragmatic appeal of the model for early postoperative monitoring.Nevertheless,several aspects warrant critical reflection,including the reliance on a postoperative variable(drainage duration),internal validation only,and certain reporting inconsistencies.This letter underscores both the promise and the limitations of adopting interpretable machine learning models in perioperative care.We advocate for transparent reporting,external validation,and careful consideration of clinically actionable timepoints before integration into practice.Ultimately,this work represents a valuable step toward precision risk stratification in gastric cancer surgery,and sets the stage for multicenter,prospective evaluations.
文摘[Objectives]To analyze the microbial community structure and diversity in the rhizosphere soil of peach trees in the Tangshan area of Hebei Province,identify the dominant microbial groups,and explore their potential ecological functions.[Methods]Amplification sequencing analysis of bacterial and fungal communities in the rhizosphere soil of a peach orchard in Qian'an County,Tangshan City,Hebei Province,was performed using Illumina MiSeq high-throughput sequencing technology.[Results]The indices of Sobs,Chao,ACE,and Shannon for soil bacteria in the rhizosphere soil of peach trees were all higher than those for fungi,indicating a more uniform and diverse bacterial community structure.At the phylum level,the bacteria with relatively high abundance included Pseudomonadota(28.29%),Acidobacteriota(18.10%),Bacillota(12.17%),and Actinomycetota(11.73%).In contrast,the fungi with relatively high abundance were Ascomycota(64.64%),Basidiomycota(14.22%),and Mortierellomycota(14.09%).At the genus level,the bacteria with relatively high abundance comprised Sphingomonas(5.00%),Priestia(3.38%),Nitrospira(2.05%),etc.The fungi with relatively high abundance included Fusarium(13.13%),Mortierella(12.86%),Tausonia(6.97%),Neocosmospora(4.77%),etc.[Conclusions]This study offers a foundational dataset and theoretical reference for the regulation of rhizosphere microecology and the management of soil health in peach orchards in Tangshan.
