Traumatic spinal cord injury often leads to the disintegration of nerve cells and axons,resulting in a substantial accumulation of myelin debris that can persist for years.The abnormal buildup of myelin debris at site...Traumatic spinal cord injury often leads to the disintegration of nerve cells and axons,resulting in a substantial accumulation of myelin debris that can persist for years.The abnormal buildup of myelin debris at sites of injury greatly impedes nerve regeneration,making the clearance of debris within these microenvironments crucial for effective post-spinal cord injury repair.In this review,we comprehensively outline the mechanisms that promote the clearance of myelin debris and myelin metabolism and summarize their roles in spinal cord injury.First,we describe the composition and characteristics of myelin debris and explain its effects on the injury site.Next,we introduce the phagocytic cells involved in myelin debris clearance,including professional phagocytes(macrophages and microglia)and non-professional phagocytes(astrocytes and microvascular endothelial cells),as well as other cells that are also proposed to participate in phagocytosis.Finally,we focus on the pathways and associated targets that enhance myelin debris clearance by phagocytes and promote lipid metabolism following spinal cord injury.Our analysis indicates that myelin debris phagocytosis is not limited to monocyte-derived macrophages,but also involves microglia,astrocytes,and microvascular endothelial cells.By modulating the expression of genes related to phagocytosis and lipid metabolism,it is possible to modulate lipid metabolism disorders and influence inflammatory phenotypes,ultimately affecting the recovery of motor function following spinal cord injury.Additionally,therapies such as targeted mitochondrial transplantation in phagocytic cells,exosome therapy,and repeated trans-spinal magnetic stimulation can effectively enhance the removal of myelin debris,presenting promising potential for future applications.展开更多
The distribution of the sediment material storage quantity along the debris flow channels(SMSQ_DFC)can provide a foundation for runoffgenerated debris flow prediction or susceptibility assessment.Current models for es...The distribution of the sediment material storage quantity along the debris flow channels(SMSQ_DFC)can provide a foundation for runoffgenerated debris flow prediction or susceptibility assessment.Current models for estimating SMSQ_DFC do not consider the capacity of the channel cross-section to accommodate sediment materials.This accommodation condition serves as a limiting factor in determining whether the expected surplus of sediment materials can ultimately be stored.To address this issue,a mass-conservative index was used to represent the balance of deposit materials at any cross-section,considering the influx from upstream,outflux to downstream,and accommodation capacity.Based on this index,a new model for estimating SMSQ_DFC was developed and subsequently evaluated.The evaluation results show that the model meets the accuracy requirements with average error rates of 14.06%for self-validation and 14.81%for generalization ability validation.To assess its practical applications,the model was applied to the Yeniu Gully in Wenchuan County,Sichuan Province,an area with detailed field survey data.The results show that the model exhibits a commendable performance.Compared to traditional theoretical and semi-theoretical statistical models,our model is easier to use(input parameters can be obtained using Geographic Information Systems(GIS)).The modeling parameters chosen in this study have more theoretical significance than those used in existing purely statistical models,offering more effective technical support for estimating SMSQ_DFC.展开更多
Non-contact debris removal methods are fuel-efficient in a single operation compared to contact-based strategies as spacecraft don’t need to match debris velocity.To comprehensively analyze this scheme,maneuvering sc...Non-contact debris removal methods are fuel-efficient in a single operation compared to contact-based strategies as spacecraft don’t need to match debris velocity.To comprehensively analyze this scheme,maneuvering schemes for maximum debris removal with minimum fuel consumption,including task assignment,sequence planning,and trajectory planning,must be formulated.The coupling between variables’dimensions and optimization results in task assignment poses challenges,as debris removal is repetitive and uncertain,leading to a vast search space.This paper proposes a novel Greedy Randomized Adaptive Search Procedure with Large Neighborhood and Crossover Mechanisms(GRASP-LNCM)to address this problem.The hybrid dynamic iteration mechanism improves computational efficiency and enhances the optimality of results.The model innovatively considers unsuccessful single removal by using a quantitative method to assess removal percentage.In addition,to improve the efficiency of sequence and trajectory planning,a Suboptimal Search Algorithm(SSA)based on the Lambert property and accelerated Multi-Revolution Lambert Problem(MRLP)solving strategy is established.Finally,a real Iridium-33 debris removal mission is studied.The simulation demonstrates that the proposed algorithm achieves state-of-the-art performance in several typical scenarios.Compared to the contact-based scheme,the new one is simpler,saving more fuel under certain conditions.展开更多
Since 2002, the Soil and Water Conservation Bureau, which is responsible for the conservation and administrative management of hillside in Taiwan, has been cooperating with Feng Chia University. Together, they have su...Since 2002, the Soil and Water Conservation Bureau, which is responsible for the conservation and administrative management of hillside in Taiwan, has been cooperating with Feng Chia University. Together, they have successfully carried out the establishment and maintenance of 13 fixed debris flow monitoring stations over the island and 2 mobile debris flow monitoring stations. During July 2004, a powerful southwest air current brought by Mindulle Typhoon caused serious flood in central and southern Taiwan. This paper aims to describe the establishment of debris flow monitoring systems in Taiwan and the observation of the debris flow event during Mindulle Typhoon at Aiyuzi River in Shenmu Village, Nantou County by the monitoring station.展开更多
The impacts of natural boulders carried by debris flows pose serious risks to the safety and reliability of structures and buildings.Natural boulders can be highly random and unpredictable.Consequently,boulder control...The impacts of natural boulders carried by debris flows pose serious risks to the safety and reliability of structures and buildings.Natural boulders can be highly random and unpredictable.Consequently,boulder control during debris flows is crucial but difficult.Herein,an eco-friendly control system featuring anchoring natural boulders(NBs)with(negative Poisson's ratio)NPR anchor cables is proposed to form an NB-NPR baffle.A series of flume experiments are conducted to verify the effect of NB-NPR baffles on controlling debris flow impact.The deployment of NB-NPR baffles substantially influences the kinematic behavior of a debris flow,primarily in the form of changes in the depositional properties and impact intensities.The results show that the NB-NPR baffle matrix successfully controls boulder mobility and exhibits positive feedback on solid particle deposition.The NB-NPR baffle group exhibits a reduction in peak impact force ranging from 29%to 79%compared to that of the control group in the basic experiment.The NPR anchor cables play a significant role in the NB-NPR baffle by demonstrating particular characteristics,including consistent resistance,large deformation,and substantial energy absorption.The NB-NPR baffle innovatively utilizes the natural boulders in a debris flow gully by converting destructive boulders into constructive boulders.Overall,this research serves as a basis for future field experiments and applications.展开更多
Machine learning-based Debris Flow Susceptibility Mapping(DFSM)has emerged as an effective approach for assessing debris flow likelihood,yet its application faces three critical challenges:insufficient reliability of ...Machine learning-based Debris Flow Susceptibility Mapping(DFSM)has emerged as an effective approach for assessing debris flow likelihood,yet its application faces three critical challenges:insufficient reliability of training samples caused by biased negative sampling,opaque decision-making mechanisms in models,and subjective susceptibility mapping methods that lack quantitative evaluation criteria.This study focuses on the Yalong River basin.By integrating high-resolution remote sensing interpretation and field surveys,we established a refined sample database that includes 1,736 debris flow gullies.To address spatial bias in traditional random negative sampling,we developed a semi-supervised optimization strategy based on iterative confidence screening.Comparative experiments with four treebased models(XGBoost,CatBoost,LGBM,and Random Forest)reveal that the optimized sampling strategy improved overall model performance by 8%-12%,with XGBoost achieving the highest accuracy(AUC=0.882)and RF performing the lowest(AUC=0.820).SHAP-based global-local interpretability analysis(applicable to all tree models)identifies elevation and short-duration rainfall as dominant controlling factors.Furthermore,among the tested tree-based models,XGBoost optimized with semisupervised sampling demonstrates the highest reliability in debris flow susceptibility mapping(DFSM),achieving a comprehensive accuracy of 83.64%due to its optimal generalization-stability equilibrium.展开更多
It is widely known that the hypervelocity impact of orbital debris can cause serious damage to spacecraft,and enhancing the impact resistance is the great concern of spacecraft shield design.This paper provides a comp...It is widely known that the hypervelocity impact of orbital debris can cause serious damage to spacecraft,and enhancing the impact resistance is the great concern of spacecraft shield design.This paper provides a comprehensive overview of advances in the development of bumper materials for spacecraft shield applications.In particular,the protective mechanism and process of the bumper using different materials against hypervelocity impact are reviewed and discussed.The advantages and disadvantages of each material used in shield were discussed,and the performance under hypervelocity impact was given according to the specific configuration.This review provides the useful reference and basis for researchers and engineers to create bumper materials for spacecraft shield applications,and the contemporary challenges and future directions for bumper materials for spacecraft shield were presented.展开更多
Recently,significant progress has been made in conceptually describing the dynamic aspects of coarse particle entrainment,which has been explored experimentally for open channel flows.The aim of this study is to exten...Recently,significant progress has been made in conceptually describing the dynamic aspects of coarse particle entrainment,which has been explored experimentally for open channel flows.The aim of this study is to extend the application of energy criterion to the low mobility aeolian transport of solids(including both natural sediment and anthropogenic debris such as plastics),ranging from incomplete(rocking)to full(rolling)entrainments.This is achieved by linking particle movements to energetic flow events,which are defined as flow structures with the ability to work on particles,setting them into motion.It is hypothesized that such events should impart sufficient energy to the particles,above a certain threshold value.The concept’s validity is demonstrated experimentally,using a wind tunnel and laser distance sensor to capture the dynamics of an individual target particle,exposed on a rough bed surface.Measurements are acquired at a high spatiotemporal resolution,and synchronously with the instantaneous air velocity at an appropriate distance upwind of the target particle,using a hot film anemometer.This enables the association of flow events with rocking and rolling entrainments.Furthermore,it is shown that rocking and rolling may have distinct energy thresholds.Estimates of the energy transfer efficiency,normalized by the drag coefficient,range over an order of magnitude(from about 0.001 to 0.0048 for rocking,up to about 0.01,for incipient rolling).The proposed event-based theoretical framework is a novel approach to characterizing the energy imparted from the wind to the soil surface and could have potential implications for modelling intermittent creep transport of coarse particles and related aeolian bedforms.展开更多
Rainstorm-induced flood hazards in mountainous areas often result in complex cascading effects by interacting with environmental and human systems.However,traditional studies typically categorize them simply as clearw...Rainstorm-induced flood hazards in mountainous areas often result in complex cascading effects by interacting with environmental and human systems.However,traditional studies typically categorize them simply as clearwater floods or debris floods/flows,overlooking their evolutionary characteristics and compound impacts.This study presents a novel classification-based approach to investigate the formation and destructive mechanisms of a catastrophic composite disaster of flash flood and debris flow in the Dayao Gully(DYG)catchment in Hanyuan County,Sichuan Province,China.The event resulted in 14 fatalities,25 missing persons,and extensive infrastructure damage.Through comprehensive field investigations and multi-method analysis,three distinct disaster zones were identified with different magnitudes and impacts:(1)a clearwater flood disaster region with minimal geomorphological changes under a 5-year return period rainfall;(2)a debris flood disaster region triggered by a 30-year return period rainfall,leading to intense sediment transport with a total deposit volume of 52,511 m^(3);and(3)a sediment-induced flood disaster region characterized by significant riverbed aggradation and infrastructure destruction due to sediment-induced blockage effects.The results reveal that the cascading characteristics of this composite disaster were primarily driven by intense rainfall,enhanced sediment transport motivated by supracritical shear stress,and interactions with human infrastructure(e.g.,bridges and buildings).This classification-based approach provides a quantitative assessment of spatial characteristics of cascading flood disasters,offering new insights into their evolutionary characteristics and highlighting the necessity for targeted disaster mitigation strategies in sedimentprone mountainous regions.展开更多
The mechanism involved in deep-seated landslide-debris flow disaster chains has been studied for many years,however,it is still not completely understood.This study aims to analyze the key factors that were involved a...The mechanism involved in deep-seated landslide-debris flow disaster chains has been studied for many years,however,it is still not completely understood.This study aims to analyze the key factors that were involved and led to the geological disaster of Shaziba 62.0 m deep landslide-debris flow.Two extensive field investigations were conducted before and after the slope failure event.The study further used drilled cores,high-density resistivity method,and aerial photographs to obtain valuable insights into the disaster chain.It was found that opencast coal mining operations broke the locked segment of the front edge and heavy rainfall softened the slip zones along the faults.Mechanical calculations demonstrated that the coupling condition of the opencast coal mining and heavy rainfall triggered the landslide.A new evolution model was put forth to describe the complex mechanism of combining progressive retreat and tractive failure of hydraulic drive landslide,which was governed by the bedding-plane rock layer.Surface runoff caused the mass of the landslide to liquefy throughout the sliding process,resulting in overlapping deposits,debris-flow-barrier-lake,and erosion.These new insights led to the indication of a different triggering mechanism of landslides-debris flows,as well as laid the foundation for the proposed physical and mechanical mechanism model based on progressive retreat soil-rock mixed landslides with an upper locked segment and lower weak interlayer under heavy rainfall.展开更多
Benefit evaluation of debris flow prevention and control projects was one of the essential contents of debris flow prevention and mitigation work.In order to scientifically and quantitatively evaluate the comprehensiv...Benefit evaluation of debris flow prevention and control projects was one of the essential contents of debris flow prevention and mitigation work.In order to scientifically and quantitatively evaluate the comprehensive benefit of debris flow prevention and control projects,this study identified nine factors as evaluation indicators from economic,social,and ecological aspects.The projection pursuit(PP) model based on the improved particle swarm optimization(IPSO) algorithm was used to construct a mathematical model to evaluate the benefit of debris flow prevention and control projects.The interpolation method was applied to divide the benefit grades.The debris flow prevention and control projects in Qipan,Taoguan,Chutou,Anjia,and Mozi gullies in Wenchuan County were chosen as typical cases for empirical analysis.The case study revealed that,among the criteria layer indicators,investment per unit of the protected area,investment per unit of the protected population,the amount of water and soil conservation,and reduction rate of accumulation fan had the most significant weights.The social and ecological benefits were found to be the more important in the target layer.The comprehensive benefit of Qipan,Taoguan,Chutou,Anjia,and Mozi gullies was found to be 4.44,4.83,1.95,3,and 2,respectively.The benefit ranking of the five gullies was consistent with their effectiveness in disaster prevention ranking in the flood season of 2019.Therefore,it could prove that the newly-built benefit evaluation model was practical and feasible,and the evaluation results of the sample could be reasonably interpreted,which verified the effectiveness of the methods.展开更多
Coarse woody debris(CWD) plays a crucial role in maintaining biodiversity in forest ecosystems by supporting habitat complexity and influencing soil properties.This study investigates the effects of CWD on gastropod d...Coarse woody debris(CWD) plays a crucial role in maintaining biodiversity in forest ecosystems by supporting habitat complexity and influencing soil properties.This study investigates the effects of CWD on gastropod diversity within managed spruce(Picea abies) forests in the Czech Republic,comparing results to nearby nature reserves(NRs).Gastropod species richness and composition were evaluated at both plot(50 m×50 m) and mesohabitat scales across gradients of CWD and beech(Fagus sylvatica) tree representation.Our results indicate significantly reduced species richness in managed forests(median 7 species per plot) compared to NRs(median15 species),attributed to lower soil pH,calcium availability,and moisture due to the dominance of spruce and the limited availability of CWD.Species richness was positively influenced by CWD volume,with two amounts identified:a minimum of 4 m^(3)·ha^(-1) to prevent significant biodiversity loss and 20 m^(3)·ha^(-1)to support sensitive and dendrophile species.At the within-plot scale,CWD was the species richest mesohabitat,playing a particularly important role in acidic and nutrient-poor environments.Furthermore,beech basal area positively correlated with species richness,mitigating the negative impact of spruce.The findings highlight the critical need for changes in forest management,including increased retention of CWD and integration of deciduous trees,to support biodiversity in intensively managed forests.These measures are particularly urgent given the susceptibility of spruce monocultures to climate change and pest outbreaks.Gastropods,as sessile indicators of environmental change,may serve as effective umbrella species for conservation efforts targeting forest soil biodiversity.展开更多
The increasing accumulation of space debris threatens the integrity and functionality of satellites and complicates orbital operations.This paper constructs an advanced rigid-flexible coupling dynamic model for tether...The increasing accumulation of space debris threatens the integrity and functionality of satellites and complicates orbital operations.This paper constructs an advanced rigid-flexible coupling dynamic model for tethered satellite systems,tailored to enhance space debris management.Utilizing the nodal position finite element method,the model significantly improves the precision of simulating tether dynamics and captures the complex interactions involving satellite and debris attitude dynamics.This advancement allows for detailed examination of potential tether entanglements and provides crucial data for optimizing deorbiting processes.To overcome the limitations of conventional control techniques,a robust adaptive sliding mode control strategy is developed.This approach is specifically designed to manage the unpredictable conditions of the low-Earth orbit and ensure precise satellite attitude control,critical for successful debris removal.Validated through extensive numerical simulations,our model and control strategy demonstrate substantial improvements in operational reliability and safety,significantly enhancing the success rate of deorbiting missions.展开更多
This study embarks on an explorative investigation into the effects of typical concentrations and varying particle sizes of fine grits(FG,the involatile portion of suspended solids)and fine debris(FD,the volatile yet ...This study embarks on an explorative investigation into the effects of typical concentrations and varying particle sizes of fine grits(FG,the involatile portion of suspended solids)and fine debris(FD,the volatile yet unbiodegradable fraction of suspended solids)within the influent on themixed liquor volatile suspended solids(MLVSS)/mixed liquor suspended solids(MLSS)ratio of an activated sludge system.Through meticulous experimentation,it was discerned that the addition of FG or FD,the particle size of FG,and the concentration of FD bore no substantial impact on the pollutant removal efficiency(denoted by the removal rate of COD and ammonia nitrogen)under constant operational conditions.However,a notable decrease in the MLVSS/MLSS ratio was observed with a typical FG concentration of 20 mg/L,with smaller FG particle sizes exacerbating this reduction.Additionally,variations in FD concentrations influenced both MLSS andMLVSS/MLSS ratios;a higher FD concentration led to an increased MLSS and a reduced MLVSS/MLSS ratio,indicating FD accumulation in the system.A predictive model for MLVSS/MLSS was constructed based on quality balance calculations,offering a tool for foreseeing the MLVSS/MLSS ratio under stable long-term influent conditions of FG and FD.This model,validated using data from the BXH wastewater treatment plant(WWTP),showcased remarkable accuracy.展开更多
Mechanical debris is an important product of friction wear, which is also a crucial approach to know the running status of a machine. Many studies have been conducted on mechanical debris in related fields such as tri...Mechanical debris is an important product of friction wear, which is also a crucial approach to know the running status of a machine. Many studies have been conducted on mechanical debris in related fields such as tribology, instrument, and diagnosis. This paper presents a comprehensive review of these studies, which summarizes wear mechanisms（e.g., abrasive wear, fatigue wear, and adhesive wear） and debris features（e.g., concentration（number）, size, morphology, and composition）, analyzes detection methods principles（e.g., offline： spectrograph and ferrograph, and online： optical method, inductive method, resistive-capacitive method, and acoustic method）,reviews developments of online inductive methods, and investigates the progress of debris-based diagnosis. Finally, several notable problems are discussed for further studies.展开更多
In this paper,a new mission model,called a multi-debris active removal mission with partial debris capture strategy,is proposed.The model assumes that a platform only captures part of the scheduled debris at a time an...In this paper,a new mission model,called a multi-debris active removal mission with partial debris capture strategy,is proposed.The model assumes that a platform only captures part of the scheduled debris at a time and then releases these debris pieces to a disposal orbit.This process is then repeated until all of the scheduled debris is removed.A genetic algorithm with a multiparameter concatenated coding method is designed to optimize the plan of a multi-debris active removal mission with a partial debris capture strategy.A set of six pieces of debris and a set of 10 pieces of debris are selected to demonstrate the proposed planning method.The result confirms the effectiveness of the genetic algorithm with the multi-parameter concatenated coding method.The new mission model provides a more comprehensive decision-making framework than the existing mission models and makes it possible to further decrease mission costs.展开更多
To characterize and recognize the debris flow-related deposits,the physico-mechanical performance of four deposits from the Dongyuege(DYG),Shawa(SW),Jiangjia Gully(JJG),and Gengdi(GD)debris flows in southwest China is...To characterize and recognize the debris flow-related deposits,the physico-mechanical performance of four deposits from the Dongyuege(DYG),Shawa(SW),Jiangjia Gully(JJG),and Gengdi(GD)debris flows in southwest China is investigated through laboratory analyses and tests.The four debris-flow materials can all be remolded into coherent,homogeneous cylinders with high densification and strength–porosity of 25%-36%,mean pore-throat radius of 0.46-5.89μm,median pore-throat radius of 0.43-4.28μm,P-wave velocity of 800-1200 m/s,modulus of elasticity of 28-103 MPa,unconfined compressive strength(UCS)of 220-760 kPa,and cohesion of 65-281 kPa.Based on the comparison in slurryability and formability among debris-flow deposits,granular flow deposits,fluvial deposits,residual lateritic clay and loess,whether a sediment can be cast into competent cylinders for physico-mechanical tests can be regarded as a diagnostic evidence of old debris-flow deposits.The discrepancy in physico-mechanical properties among the four debris-flow deposits suggests that the combination of foregoing physico-mechanical parameters can characterize assembling characteristics of debris flow-related sediments including grain size distribution,mineralogy,and accidental detritus.Four deposited sediments above can be surprisingly classified as hard soil-soft rocks according to UCS,and the hard soil-soft rock behaviors can advance the further understanding of debris flows.展开更多
[Objective] The aim of this study was to evaluate the economic loss caused by Zhouqu debris flow. [Method] After the large debris flows happened on August 7, 2010 in Zhouqu, Gansu Province, we collected data at the fi...[Objective] The aim of this study was to evaluate the economic loss caused by Zhouqu debris flow. [Method] After the large debris flows happened on August 7, 2010 in Zhouqu, Gansu Province, we collected data at the first time after the disaster, and then built an assessment model to estimate the potential economic losses. [Result] The total loss reached 16.57×10^2 million Yuan, in which indirect economic loss was up to 2.42×10^2 million yaun while the actual direct economic loss was around 14.15×10^2 million Yuan. [Conclusion] The proportional coefficient method is a rapid and efficient method for evaluating the indirect loss caused by disasters.展开更多
This study was conducted in Erdaobaihe River passing through the broadleaved and Korean pine forest located on the north slope of Changbai Mountain. In-stream large woody debris (LWD) in two segments of the river chan...This study was conducted in Erdaobaihe River passing through the broadleaved and Korean pine forest located on the north slope of Changbai Mountain. In-stream large woody debris (LWD) in two segments of the river channel was investigated with base diameter, top diameter, length, and decay class. To study relationship between in-stream LWD and adjacent riparian forest, species of each log of LWD in segment 1 was identified, and the riparian forest was examined by setting a 32m?4 m quadrat consisting of twelve 8m?m small quadrats. The results showed that, in segment 1, in-stream LWD loading was 1.733 m3/100m or 10.83 m3hm-2, and in segment 2, it was 1.709m3/100m or 21.36 m3hm-2. In-stream LWD in decay class III and IV were accounted for a high proportion, which was different from that in the broadleaved and Korean pine forest, and the possible reason might be different decomposing velocities due to different decomposing conditions. Logs of LWD in stream and living trees in riparian forest declined as diameter increased, and it was in a reverse J-shaped distribution except logs of LWD in segment 1 in the first diameter class. Volumes of LWD in stream and living trees in riparian forest increased as diameter increased, and it was in a typical J-shaped distribution. Loading and species component of in-stream LWD were correlative to status of riparian forest to a certain extent, and there also existed difference. Comparing the correlation and difference was helpful to study on dynamic of the riparian forest.展开更多
By inspecting and analyzing the debris, which is the most direct and important information units in the lubricating oil, we can monitor the machine condition to predict its failure. The debris monitoring and analyzing...By inspecting and analyzing the debris, which is the most direct and important information units in the lubricating oil, we can monitor the machine condition to predict its failure. The debris monitoring and analyzing system (DMAS) is developed from the traditional iron spectrum technology, and has such characteristics as ease for debris separating, forecasting machine failure automatically and accurately in time and so on. The fundamental theory, components and its application in aeroengine health monitoring of DMAS are presented.展开更多
基金supported by the National Natural Science Foundation of China,Nos.82271411(to RG),51803072(to WL)the International Cooperative Project of Talent Cultivation“Xinghai Project”at the China-Japan Union Hospital of Jilin University,No.XHLH202404(to WL)+1 种基金the Science and Technology Development Plan of Jilin Province,No.YDZJ202201ZYTS038(to WL)Jilin Provincial Finance Program,No.2022SCZ10(to WL)。
文摘Traumatic spinal cord injury often leads to the disintegration of nerve cells and axons,resulting in a substantial accumulation of myelin debris that can persist for years.The abnormal buildup of myelin debris at sites of injury greatly impedes nerve regeneration,making the clearance of debris within these microenvironments crucial for effective post-spinal cord injury repair.In this review,we comprehensively outline the mechanisms that promote the clearance of myelin debris and myelin metabolism and summarize their roles in spinal cord injury.First,we describe the composition and characteristics of myelin debris and explain its effects on the injury site.Next,we introduce the phagocytic cells involved in myelin debris clearance,including professional phagocytes(macrophages and microglia)and non-professional phagocytes(astrocytes and microvascular endothelial cells),as well as other cells that are also proposed to participate in phagocytosis.Finally,we focus on the pathways and associated targets that enhance myelin debris clearance by phagocytes and promote lipid metabolism following spinal cord injury.Our analysis indicates that myelin debris phagocytosis is not limited to monocyte-derived macrophages,but also involves microglia,astrocytes,and microvascular endothelial cells.By modulating the expression of genes related to phagocytosis and lipid metabolism,it is possible to modulate lipid metabolism disorders and influence inflammatory phenotypes,ultimately affecting the recovery of motor function following spinal cord injury.Additionally,therapies such as targeted mitochondrial transplantation in phagocytic cells,exosome therapy,and repeated trans-spinal magnetic stimulation can effectively enhance the removal of myelin debris,presenting promising potential for future applications.
基金supported by Geological Disaster Patterns and Mitigation Strategies Under River-Reservoir Hydrodynamics in the Three Gorges Reservoir Fluctuation Zone(5000002024CC20004)the National Key Research and Development Program of China(2023YFC3007205)+1 种基金the National Natural Science Foundation of China(No.42271013)the West Light Foundation of the Chinese Academy of Sciences.
文摘The distribution of the sediment material storage quantity along the debris flow channels(SMSQ_DFC)can provide a foundation for runoffgenerated debris flow prediction or susceptibility assessment.Current models for estimating SMSQ_DFC do not consider the capacity of the channel cross-section to accommodate sediment materials.This accommodation condition serves as a limiting factor in determining whether the expected surplus of sediment materials can ultimately be stored.To address this issue,a mass-conservative index was used to represent the balance of deposit materials at any cross-section,considering the influx from upstream,outflux to downstream,and accommodation capacity.Based on this index,a new model for estimating SMSQ_DFC was developed and subsequently evaluated.The evaluation results show that the model meets the accuracy requirements with average error rates of 14.06%for self-validation and 14.81%for generalization ability validation.To assess its practical applications,the model was applied to the Yeniu Gully in Wenchuan County,Sichuan Province,an area with detailed field survey data.The results show that the model exhibits a commendable performance.Compared to traditional theoretical and semi-theoretical statistical models,our model is easier to use(input parameters can be obtained using Geographic Information Systems(GIS)).The modeling parameters chosen in this study have more theoretical significance than those used in existing purely statistical models,offering more effective technical support for estimating SMSQ_DFC.
基金co-supported by the National Natural Science Foundation of China(Nos.U23B6001,62273118,12150008)the Fundamental Research Funds for the Central Universities,China(No.2023FRFK02043)+1 种基金the Natural Science Foundation of Heilongjiang Province,China(No.LH2022F023)China Aerospace Science and Technology Corporation Youth Talent Support Program.
文摘Non-contact debris removal methods are fuel-efficient in a single operation compared to contact-based strategies as spacecraft don’t need to match debris velocity.To comprehensively analyze this scheme,maneuvering schemes for maximum debris removal with minimum fuel consumption,including task assignment,sequence planning,and trajectory planning,must be formulated.The coupling between variables’dimensions and optimization results in task assignment poses challenges,as debris removal is repetitive and uncertain,leading to a vast search space.This paper proposes a novel Greedy Randomized Adaptive Search Procedure with Large Neighborhood and Crossover Mechanisms(GRASP-LNCM)to address this problem.The hybrid dynamic iteration mechanism improves computational efficiency and enhances the optimality of results.The model innovatively considers unsuccessful single removal by using a quantitative method to assess removal percentage.In addition,to improve the efficiency of sequence and trajectory planning,a Suboptimal Search Algorithm(SSA)based on the Lambert property and accelerated Multi-Revolution Lambert Problem(MRLP)solving strategy is established.Finally,a real Iridium-33 debris removal mission is studied.The simulation demonstrates that the proposed algorithm achieves state-of-the-art performance in several typical scenarios.Compared to the contact-based scheme,the new one is simpler,saving more fuel under certain conditions.
基金Taiwan Soil and Water Conservation Bureau (SWCB- 95-164)
文摘Since 2002, the Soil and Water Conservation Bureau, which is responsible for the conservation and administrative management of hillside in Taiwan, has been cooperating with Feng Chia University. Together, they have successfully carried out the establishment and maintenance of 13 fixed debris flow monitoring stations over the island and 2 mobile debris flow monitoring stations. During July 2004, a powerful southwest air current brought by Mindulle Typhoon caused serious flood in central and southern Taiwan. This paper aims to describe the establishment of debris flow monitoring systems in Taiwan and the observation of the debris flow event during Mindulle Typhoon at Aiyuzi River in Shenmu Village, Nantou County by the monitoring station.
基金financial support from the National Natural Science Foundation of China(Grant No.41941018).
文摘The impacts of natural boulders carried by debris flows pose serious risks to the safety and reliability of structures and buildings.Natural boulders can be highly random and unpredictable.Consequently,boulder control during debris flows is crucial but difficult.Herein,an eco-friendly control system featuring anchoring natural boulders(NBs)with(negative Poisson's ratio)NPR anchor cables is proposed to form an NB-NPR baffle.A series of flume experiments are conducted to verify the effect of NB-NPR baffles on controlling debris flow impact.The deployment of NB-NPR baffles substantially influences the kinematic behavior of a debris flow,primarily in the form of changes in the depositional properties and impact intensities.The results show that the NB-NPR baffle matrix successfully controls boulder mobility and exhibits positive feedback on solid particle deposition.The NB-NPR baffle group exhibits a reduction in peak impact force ranging from 29%to 79%compared to that of the control group in the basic experiment.The NPR anchor cables play a significant role in the NB-NPR baffle by demonstrating particular characteristics,including consistent resistance,large deformation,and substantial energy absorption.The NB-NPR baffle innovatively utilizes the natural boulders in a debris flow gully by converting destructive boulders into constructive boulders.Overall,this research serves as a basis for future field experiments and applications.
基金funded by the Second Tibetan Plateau Scientific Expedition and Research,Ministry of Science and Technology(Project No.2019QZKK0902)the West Light Foundation of the Chinese Academy of Sciences(Project No.E3R2120)the Research Programme of Institute of Mountain Hazards and Environment,Chinese Academy of Sciences(Project No.IMHE-ZDRW-01).
文摘Machine learning-based Debris Flow Susceptibility Mapping(DFSM)has emerged as an effective approach for assessing debris flow likelihood,yet its application faces three critical challenges:insufficient reliability of training samples caused by biased negative sampling,opaque decision-making mechanisms in models,and subjective susceptibility mapping methods that lack quantitative evaluation criteria.This study focuses on the Yalong River basin.By integrating high-resolution remote sensing interpretation and field surveys,we established a refined sample database that includes 1,736 debris flow gullies.To address spatial bias in traditional random negative sampling,we developed a semi-supervised optimization strategy based on iterative confidence screening.Comparative experiments with four treebased models(XGBoost,CatBoost,LGBM,and Random Forest)reveal that the optimized sampling strategy improved overall model performance by 8%-12%,with XGBoost achieving the highest accuracy(AUC=0.882)and RF performing the lowest(AUC=0.820).SHAP-based global-local interpretability analysis(applicable to all tree models)identifies elevation and short-duration rainfall as dominant controlling factors.Furthermore,among the tested tree-based models,XGBoost optimized with semisupervised sampling demonstrates the highest reliability in debris flow susceptibility mapping(DFSM),achieving a comprehensive accuracy of 83.64%due to its optimal generalization-stability equilibrium.
基金supported by National Natural Science Foundation of China(Grant Nos.12202068,12202087)China National Space Administration Preliminary Research Project(Grant Nos.KJSP2023020201,KJSP2020010402).
文摘It is widely known that the hypervelocity impact of orbital debris can cause serious damage to spacecraft,and enhancing the impact resistance is the great concern of spacecraft shield design.This paper provides a comprehensive overview of advances in the development of bumper materials for spacecraft shield applications.In particular,the protective mechanism and process of the bumper using different materials against hypervelocity impact are reviewed and discussed.The advantages and disadvantages of each material used in shield were discussed,and the performance under hypervelocity impact was given according to the specific configuration.This review provides the useful reference and basis for researchers and engineers to create bumper materials for spacecraft shield applications,and the contemporary challenges and future directions for bumper materials for spacecraft shield were presented.
基金supported by the National Natural Science Foundation of China (Grants Nos.41171005,41071005,12272344,and 12350710176)the Ministry of Science and Technology of the People’s Republic of China (Grant No.2013CB956000).
文摘Recently,significant progress has been made in conceptually describing the dynamic aspects of coarse particle entrainment,which has been explored experimentally for open channel flows.The aim of this study is to extend the application of energy criterion to the low mobility aeolian transport of solids(including both natural sediment and anthropogenic debris such as plastics),ranging from incomplete(rocking)to full(rolling)entrainments.This is achieved by linking particle movements to energetic flow events,which are defined as flow structures with the ability to work on particles,setting them into motion.It is hypothesized that such events should impart sufficient energy to the particles,above a certain threshold value.The concept’s validity is demonstrated experimentally,using a wind tunnel and laser distance sensor to capture the dynamics of an individual target particle,exposed on a rough bed surface.Measurements are acquired at a high spatiotemporal resolution,and synchronously with the instantaneous air velocity at an appropriate distance upwind of the target particle,using a hot film anemometer.This enables the association of flow events with rocking and rolling entrainments.Furthermore,it is shown that rocking and rolling may have distinct energy thresholds.Estimates of the energy transfer efficiency,normalized by the drag coefficient,range over an order of magnitude(from about 0.001 to 0.0048 for rocking,up to about 0.01,for incipient rolling).The proposed event-based theoretical framework is a novel approach to characterizing the energy imparted from the wind to the soil surface and could have potential implications for modelling intermittent creep transport of coarse particles and related aeolian bedforms.
基金supported by National Natural Science Foundation of Joint Fund for Changjiang River Water Science Research(U2340201)National Natural Science Foundation of China(52239006)Natural Science Foundation of Sichuan Province(2024NSFSC0005).
文摘Rainstorm-induced flood hazards in mountainous areas often result in complex cascading effects by interacting with environmental and human systems.However,traditional studies typically categorize them simply as clearwater floods or debris floods/flows,overlooking their evolutionary characteristics and compound impacts.This study presents a novel classification-based approach to investigate the formation and destructive mechanisms of a catastrophic composite disaster of flash flood and debris flow in the Dayao Gully(DYG)catchment in Hanyuan County,Sichuan Province,China.The event resulted in 14 fatalities,25 missing persons,and extensive infrastructure damage.Through comprehensive field investigations and multi-method analysis,three distinct disaster zones were identified with different magnitudes and impacts:(1)a clearwater flood disaster region with minimal geomorphological changes under a 5-year return period rainfall;(2)a debris flood disaster region triggered by a 30-year return period rainfall,leading to intense sediment transport with a total deposit volume of 52,511 m^(3);and(3)a sediment-induced flood disaster region characterized by significant riverbed aggradation and infrastructure destruction due to sediment-induced blockage effects.The results reveal that the cascading characteristics of this composite disaster were primarily driven by intense rainfall,enhanced sediment transport motivated by supracritical shear stress,and interactions with human infrastructure(e.g.,bridges and buildings).This classification-based approach provides a quantitative assessment of spatial characteristics of cascading flood disasters,offering new insights into their evolutionary characteristics and highlighting the necessity for targeted disaster mitigation strategies in sedimentprone mountainous regions.
基金the Key Research and Development Project of Hubei Province(No.2021BCA219)。
文摘The mechanism involved in deep-seated landslide-debris flow disaster chains has been studied for many years,however,it is still not completely understood.This study aims to analyze the key factors that were involved and led to the geological disaster of Shaziba 62.0 m deep landslide-debris flow.Two extensive field investigations were conducted before and after the slope failure event.The study further used drilled cores,high-density resistivity method,and aerial photographs to obtain valuable insights into the disaster chain.It was found that opencast coal mining operations broke the locked segment of the front edge and heavy rainfall softened the slip zones along the faults.Mechanical calculations demonstrated that the coupling condition of the opencast coal mining and heavy rainfall triggered the landslide.A new evolution model was put forth to describe the complex mechanism of combining progressive retreat and tractive failure of hydraulic drive landslide,which was governed by the bedding-plane rock layer.Surface runoff caused the mass of the landslide to liquefy throughout the sliding process,resulting in overlapping deposits,debris-flow-barrier-lake,and erosion.These new insights led to the indication of a different triggering mechanism of landslides-debris flows,as well as laid the foundation for the proposed physical and mechanical mechanism model based on progressive retreat soil-rock mixed landslides with an upper locked segment and lower weak interlayer under heavy rainfall.
基金financially supported by the National Key Research and Development Program(No.2018YFC1505402)the National Natural Science Foundation of China(No.41871174)+1 种基金the Science and Technology Department of Sichuan Province(No.2020YFSY0013)the Fundamental Research Funds for the Central Universities Project(No.2682019CX19)。
文摘Benefit evaluation of debris flow prevention and control projects was one of the essential contents of debris flow prevention and mitigation work.In order to scientifically and quantitatively evaluate the comprehensive benefit of debris flow prevention and control projects,this study identified nine factors as evaluation indicators from economic,social,and ecological aspects.The projection pursuit(PP) model based on the improved particle swarm optimization(IPSO) algorithm was used to construct a mathematical model to evaluate the benefit of debris flow prevention and control projects.The interpolation method was applied to divide the benefit grades.The debris flow prevention and control projects in Qipan,Taoguan,Chutou,Anjia,and Mozi gullies in Wenchuan County were chosen as typical cases for empirical analysis.The case study revealed that,among the criteria layer indicators,investment per unit of the protected area,investment per unit of the protected population,the amount of water and soil conservation,and reduction rate of accumulation fan had the most significant weights.The social and ecological benefits were found to be the more important in the target layer.The comprehensive benefit of Qipan,Taoguan,Chutou,Anjia,and Mozi gullies was found to be 4.44,4.83,1.95,3,and 2,respectively.The benefit ranking of the five gullies was consistent with their effectiveness in disaster prevention ranking in the flood season of 2019.Therefore,it could prove that the newly-built benefit evaluation model was practical and feasible,and the evaluation results of the sample could be reasonably interpreted,which verified the effectiveness of the methods.
基金fnancially supported by the Czech Science Foundation(P504/23-05132S)by the Masaryk University Institutional Grant for Doctoral Students(MUNI/A/1667/2024).
文摘Coarse woody debris(CWD) plays a crucial role in maintaining biodiversity in forest ecosystems by supporting habitat complexity and influencing soil properties.This study investigates the effects of CWD on gastropod diversity within managed spruce(Picea abies) forests in the Czech Republic,comparing results to nearby nature reserves(NRs).Gastropod species richness and composition were evaluated at both plot(50 m×50 m) and mesohabitat scales across gradients of CWD and beech(Fagus sylvatica) tree representation.Our results indicate significantly reduced species richness in managed forests(median 7 species per plot) compared to NRs(median15 species),attributed to lower soil pH,calcium availability,and moisture due to the dominance of spruce and the limited availability of CWD.Species richness was positively influenced by CWD volume,with two amounts identified:a minimum of 4 m^(3)·ha^(-1) to prevent significant biodiversity loss and 20 m^(3)·ha^(-1)to support sensitive and dendrophile species.At the within-plot scale,CWD was the species richest mesohabitat,playing a particularly important role in acidic and nutrient-poor environments.Furthermore,beech basal area positively correlated with species richness,mitigating the negative impact of spruce.The findings highlight the critical need for changes in forest management,including increased retention of CWD and integration of deciduous trees,to support biodiversity in intensively managed forests.These measures are particularly urgent given the susceptibility of spruce monocultures to climate change and pest outbreaks.Gastropods,as sessile indicators of environmental change,may serve as effective umbrella species for conservation efforts targeting forest soil biodiversity.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.62173107 and 12202058)the Young Elite Scientists Sponsorship Program by Beijing Association for Science and Technology(Grant No.BYESS2023344).
文摘The increasing accumulation of space debris threatens the integrity and functionality of satellites and complicates orbital operations.This paper constructs an advanced rigid-flexible coupling dynamic model for tethered satellite systems,tailored to enhance space debris management.Utilizing the nodal position finite element method,the model significantly improves the precision of simulating tether dynamics and captures the complex interactions involving satellite and debris attitude dynamics.This advancement allows for detailed examination of potential tether entanglements and provides crucial data for optimizing deorbiting processes.To overcome the limitations of conventional control techniques,a robust adaptive sliding mode control strategy is developed.This approach is specifically designed to manage the unpredictable conditions of the low-Earth orbit and ensure precise satellite attitude control,critical for successful debris removal.Validated through extensive numerical simulations,our model and control strategy demonstrate substantial improvements in operational reliability and safety,significantly enhancing the success rate of deorbiting missions.
基金supported by the National Special Project for Science and Technology on Water Pollution Control and Management(No.2017ZX07102-003)the Fundamental Research Funds for the Central Universities,and the Research Funds of Renmin University of China(No.2020030257).
文摘This study embarks on an explorative investigation into the effects of typical concentrations and varying particle sizes of fine grits(FG,the involatile portion of suspended solids)and fine debris(FD,the volatile yet unbiodegradable fraction of suspended solids)within the influent on themixed liquor volatile suspended solids(MLVSS)/mixed liquor suspended solids(MLSS)ratio of an activated sludge system.Through meticulous experimentation,it was discerned that the addition of FG or FD,the particle size of FG,and the concentration of FD bore no substantial impact on the pollutant removal efficiency(denoted by the removal rate of COD and ammonia nitrogen)under constant operational conditions.However,a notable decrease in the MLVSS/MLSS ratio was observed with a typical FG concentration of 20 mg/L,with smaller FG particle sizes exacerbating this reduction.Additionally,variations in FD concentrations influenced both MLSS andMLVSS/MLSS ratios;a higher FD concentration led to an increased MLSS and a reduced MLVSS/MLSS ratio,indicating FD accumulation in the system.A predictive model for MLVSS/MLSS was constructed based on quality balance calculations,offering a tool for foreseeing the MLVSS/MLSS ratio under stable long-term influent conditions of FG and FD.This model,validated using data from the BXH wastewater treatment plant(WWTP),showcased remarkable accuracy.
基金supported by the National Natural Science Foundation of China(Nos.51620105010 and 51575019)the National Basic Research Program of China(No.2014CB046402)Singapore Energy Innovation Research Programme(Gas Technology Grant No.NRF2014EWT-EIRP003-014)
文摘Mechanical debris is an important product of friction wear, which is also a crucial approach to know the running status of a machine. Many studies have been conducted on mechanical debris in related fields such as tribology, instrument, and diagnosis. This paper presents a comprehensive review of these studies, which summarizes wear mechanisms（e.g., abrasive wear, fatigue wear, and adhesive wear） and debris features（e.g., concentration（number）, size, morphology, and composition）, analyzes detection methods principles（e.g., offline： spectrograph and ferrograph, and online： optical method, inductive method, resistive-capacitive method, and acoustic method）,reviews developments of online inductive methods, and investigates the progress of debris-based diagnosis. Finally, several notable problems are discussed for further studies.
基金co-supported by the Open Fund Project of Space Intelligent Control Technology Laboratory(No.HTKJ2021KL502010)the Research Project of Space Debris and Near-earth Asteroid Defense Grants,China(No.KJSP 2020010303)the National Natural Science Foundation of China(No.11802130).
文摘In this paper,a new mission model,called a multi-debris active removal mission with partial debris capture strategy,is proposed.The model assumes that a platform only captures part of the scheduled debris at a time and then releases these debris pieces to a disposal orbit.This process is then repeated until all of the scheduled debris is removed.A genetic algorithm with a multiparameter concatenated coding method is designed to optimize the plan of a multi-debris active removal mission with a partial debris capture strategy.A set of six pieces of debris and a set of 10 pieces of debris are selected to demonstrate the proposed planning method.The result confirms the effectiveness of the genetic algorithm with the multi-parameter concatenated coding method.The new mission model provides a more comprehensive decision-making framework than the existing mission models and makes it possible to further decrease mission costs.
基金Project(41931294)supported by the National Natural Science Foundation of ChinaProjects(U1502232,U1033601)supported by the National Natural Science Foundation of China-Yunnan Joint Fund。
文摘To characterize and recognize the debris flow-related deposits,the physico-mechanical performance of four deposits from the Dongyuege(DYG),Shawa(SW),Jiangjia Gully(JJG),and Gengdi(GD)debris flows in southwest China is investigated through laboratory analyses and tests.The four debris-flow materials can all be remolded into coherent,homogeneous cylinders with high densification and strength–porosity of 25%-36%,mean pore-throat radius of 0.46-5.89μm,median pore-throat radius of 0.43-4.28μm,P-wave velocity of 800-1200 m/s,modulus of elasticity of 28-103 MPa,unconfined compressive strength(UCS)of 220-760 kPa,and cohesion of 65-281 kPa.Based on the comparison in slurryability and formability among debris-flow deposits,granular flow deposits,fluvial deposits,residual lateritic clay and loess,whether a sediment can be cast into competent cylinders for physico-mechanical tests can be regarded as a diagnostic evidence of old debris-flow deposits.The discrepancy in physico-mechanical properties among the four debris-flow deposits suggests that the combination of foregoing physico-mechanical parameters can characterize assembling characteristics of debris flow-related sediments including grain size distribution,mineralogy,and accidental detritus.Four deposited sediments above can be surprisingly classified as hard soil-soft rocks according to UCS,and the hard soil-soft rock behaviors can advance the further understanding of debris flows.
基金Supported by National Key Technology Research and Development Program(2008BAK50B06)~~
文摘[Objective] The aim of this study was to evaluate the economic loss caused by Zhouqu debris flow. [Method] After the large debris flows happened on August 7, 2010 in Zhouqu, Gansu Province, we collected data at the first time after the disaster, and then built an assessment model to estimate the potential economic losses. [Result] The total loss reached 16.57×10^2 million Yuan, in which indirect economic loss was up to 2.42×10^2 million yaun while the actual direct economic loss was around 14.15×10^2 million Yuan. [Conclusion] The proportional coefficient method is a rapid and efficient method for evaluating the indirect loss caused by disasters.
基金This paper was supported by the Chinese Academy of Sciences (KZCX2-406) and National Natural Science Foundation of China (NSFC39970123) and Changbai Mountain Open Research Station.
文摘This study was conducted in Erdaobaihe River passing through the broadleaved and Korean pine forest located on the north slope of Changbai Mountain. In-stream large woody debris (LWD) in two segments of the river channel was investigated with base diameter, top diameter, length, and decay class. To study relationship between in-stream LWD and adjacent riparian forest, species of each log of LWD in segment 1 was identified, and the riparian forest was examined by setting a 32m?4 m quadrat consisting of twelve 8m?m small quadrats. The results showed that, in segment 1, in-stream LWD loading was 1.733 m3/100m or 10.83 m3hm-2, and in segment 2, it was 1.709m3/100m or 21.36 m3hm-2. In-stream LWD in decay class III and IV were accounted for a high proportion, which was different from that in the broadleaved and Korean pine forest, and the possible reason might be different decomposing velocities due to different decomposing conditions. Logs of LWD in stream and living trees in riparian forest declined as diameter increased, and it was in a reverse J-shaped distribution except logs of LWD in segment 1 in the first diameter class. Volumes of LWD in stream and living trees in riparian forest increased as diameter increased, and it was in a typical J-shaped distribution. Loading and species component of in-stream LWD were correlative to status of riparian forest to a certain extent, and there also existed difference. Comparing the correlation and difference was helpful to study on dynamic of the riparian forest.
文摘By inspecting and analyzing the debris, which is the most direct and important information units in the lubricating oil, we can monitor the machine condition to predict its failure. The debris monitoring and analyzing system (DMAS) is developed from the traditional iron spectrum technology, and has such characteristics as ease for debris separating, forecasting machine failure automatically and accurately in time and so on. The fundamental theory, components and its application in aeroengine health monitoring of DMAS are presented.
