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Temporal variability of global potential water erosion based on an improved USLE model

International Soil and Water Conservation Research 2024年第1期12卷 1-12页

作者： Jialei li Muqi Xiong Ranhao sun liding Chen State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing100085China University of Chinese Academy of Sciences Beijing100049China Key Laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing100101China

Assessing spatiotemporal variation in global soil erosion is essential for identifying areas that require greater attention and management under the effects of anthropogenic activities and climate *** erosion can be modelled using the universal soil loss equation(USLE),which includes rainfall erosivity(R-factor),vegetation cover(C-factor),topography(LS-factor),soil erodibility(K-factor),and management practices(P-factor).However,global soil erosion modeling faces numerous challenges,including data acquisition,calculation processes,and parameter calibration under different climatic and topographic ***,we presented an improved USLE-based model using highly distributed *** R-,C-,and P-factors were modified by the climate zone,country,and *** distributed model was applied to estimate the intensity and variations in global soil erosion from 1992 to *** validated the accuracy of this model by comparing simulations with measurements from 11,439 plot years of erosion *** results showed that i)the average global erosion rate was 5.78 t ha^(-1)year^(-1),with an increase rate of 4.26×10^(-3)t ha^(-1)year^(-1);ii)areas with significantly increasing erosion accounted for 16%of the land with water erosion,whereas those with significantly decreasing erosion accounted for 7%;and iii)areas with severe erosion included the western Ghats,Abyssinian Plateau,Brazilian Plateau,south and east of the Himalayas,and western coast of South *** erosion occurred mainly on the Amazon Plain and the northern coast of the *** study provides an improved water erosion prediction model and accurate information for researchers and policymakers to identify the drivers underlying changes in water erosion in different regions.

关键词： Soil erosion Distributed USLE model Rainfall erosivity Soil conservation Global change

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Characteristics and Mechanisms of Persistent Wet–Cold Events with Different Cold-air Paths in South China

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Advances in Atmospheric Sciences 2024年第6期41卷 1171-1183页

作者： Xiaojuan sun li CHEN Chuhan LU Panxing WANG Key Laboratory of Meteorological Disaster Ministry of Education/Collaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNanjing University of Information Science and TechnologyNanjing 210044China School of Atmospheric Sciences Nanjing University of Information Science and TechnologyNanjing 210044China Qianxinan Bouyei and Miao Autonomous Prefecture Meteorological Bureau of Guizhou Province Xingyi 562400China

We investigate the characteristics and mechanisms of persistent wet–cold events(PWCEs)with different types of coldair *** show that the cumulative single-station frequency of the PWCEs in the western part of South China is higher than that in the eastern *** pattern of single-station frequency of the PWCEs are“Yangtze River(YR)uniform”and“east–west inverse”.The YR uniform pattern is the dominant mode,so we focus on this *** cold-air paths for PWCEs of the YR uniform pattern are divided into three types—namely,the west,northwest and north types—among which the west type accounts for the largest *** differences in atmospheric circulation of the PWCEs under the three types of paths are *** thermal inversion layer in the lower troposphere is favorable for precipitation during the *** positive water vapor budget for the three types of PWCEs mainly appears at the southern boundary.

关键词： persistent wet–cold events cold-air paths circulation characteristics water vapor

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Engineering phonon thermal transport in few-layer PdSe_(2)

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Frontiers of physics 2024年第3期19卷 135-141页

作者： Meilin li Huanhuan sun Jun Zhou Yunshan Zhao Phonon Engineering Research Center of Jiangsu Province Center for Quantum Transport and Thermal Energy ScienceInstitute of Physics Frontiers and Interdisciplinary SciencesSchool of Physics and TechnologyNanjing Normal UniversityNanjing 210023China

Engineering phonon transport in low-dimensional materials has great significance not only for fundamental research,but also for thermal management applications of electric ***,due to the difficulties of micro and nano processing and characterization techniques,the work on tuning phonon transport at nanoscale are *** this work,by introducing Ar+plasma,we probed the phonon transport in two-dimensional(2D)layered semiconductor PdSe_(2)under different defect *** using thermal bridge method,the thermal conductivity was measured to decrease by 50%after a certain Ar+irradiation,which implied a possible phase ***,Raman characterizations were performed to show that the Raman sensitive peaks of PdSe_(2)was red-shifted and finally became disappeared with the increase of defect concentration.“Defect engineering”proves be a practical strategy in tuning the phonon thermal transport in low-dimensional materials,thus providing guidance for potential application in designing thermoelectric devices with various emerging materials.

关键词： phonon transport PdSe_(2) defects thermal bridge method

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New formula for predicting the plastic buckling pressure of steel torispherical heads under internal pressure

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第8期25卷 618-630页

作者： Sheng YE Keming li Jinyang ZHENG Shan sun Institute of Process Equipment Zhejiang UniversityHangzhou 310027China Engineering Research Center for High Pressure Process Equipment and Safety of Ministry of Education Hangzhou 310027China State Key Laboratory of Fluid Power and Mechatronic Systems Hangzhou 310058China

Thin-walled torispherical heads under internal pressure can fail by plastic buckling because of compressive circumferential stresses in the head ***,existing formulas still have limitations,such as complicated expressions and low accuracy,in determining buckling *** this paper,we propose a new formula for calculating the buckling pressure of torispherical heads based on elastic-plastic analysis and experimental ***,a finite element(FE)method based on the arc-length method is established to calculate the plastic buckling pressure of torispherical heads,considering the effects of material strain hardening and geometrical *** buckling pressure results calculated by the FE method in this paper have good consistency with those of BOSOR5,which is a program for calculating the elastic-plastic bifurcation buckling pressure based on the finite difference energy ***,the effects of geometric parameters,material parameters,and restraint form of head edge on buckling pressure are ***,a new formula for calculating plastic buckling pressure is developed by fitting the curve of FE results and introducing a reduction factor determined from experimental ***,based on the experimental results,we compare the predictions of the new formula with those of existing *** is shown that the new formula has a higher accuracy than the existing ones.

关键词： Torispherical head Plastic buckling Elastic-plastic analysis Prediction formula Finite element method

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The biosynthesis of alarm pheromone in the wheat aphid Rhopalosiphum padi is regulated by hormones via fatty acid metabolism

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Journal of Integrative Agriculture 2024年第7期23卷 2346-2361页

作者： Chengxian sun Yaoguo Qin Julian Chen Zhengxi li Department of Entomology/Ministry of Agriculture Key Laboratory for Monitoring and Environment-friendly Control of Crop Pests College of Plant ProtectionChina Agricultural UniversityBeijing 100193China State Key Laboratory for Biology of Plant Diseases and Insect Pests Institute of Plant ProtectionChinese Academy of Agricultural SciencesBeijing 100193China

Aphids are major insect pests in agriculture and forestry *** attacks by natural enemies,many aphids release an alarm pheromone to protect their *** most aphids,the main component of the aphid alarm pheromone(AAP)is the sesquiterpene hydrocarbon(E)-β-farnesene(EβF).However,the mechanisms behind its biosynthesis and regulation remain poorly *** this study,we used the bird cherry–oat aphid Rhopalosiphum padi,which is an important wheat aphid,to investigate the regulatory mechanisms of EβF *** results showed that EβF biosynthesis occurs during the mature embryo period and the molting period of the 1st-and 2nd-instar *** provide the prerequisite material for EβF production and *** on transcriptome sequencing,RNAi analysis,hormone treatments,and quantitative measurements,we found that the biosynthesis of EβF utilizes acetyl coenzyme A produced from fatty acid degradation,which can be suppressed by juvenile hormone but it is promoted by 20-hydroxyecdysone through the modulation of fatty acid *** is the first systemic study on the modulation of EβF production in *** results of our study provide insights into the molecular regulatory mechanisms of AAP biosynthesis,as well as valuable information for designing potential aphid control strategies.

关键词： (E)-β-farnesene critical period for biosynthesis fatty acid metabolism juvenile hormone 20-hydroxyecdysone

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MTCR-CR Routing Strategy for Connection-Oriented Routing over Satellite Networks

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China Communications 2024年第5期21卷 280-296页

作者： li Changhao sun Xue Yan Lei Cao Suzhi The University of Chinese Academy of Sciences Beijing 100094China Key Laboratory of Space Utilization Chinese Academy of SciencesBeijing 100094China Technology and Engineering Center for Space Utilization Chinese Academy of SciencesBeijing 100094China

The high-speed movement of satellites makes it not feasible to directly apply the mature routing scheme on the ground to the satellite ***-DVTR in the snapshot-based connectionoriented routing strategy is one of the representative solutions,but it still has room for improvement in terms of routing *** this paper,we propose an improved scheme for connection-oriented routing strategy named the Minimal Topology Change Routing based on Collaborative Rules(MTCR-CR).The MTCR-CR uses continuous time static topology snapshots based on satellite status to search for intersatellite link(ISL)construction solutions that meet the minimum number of topology changes to avoid route *** simulation results in Beidou-3 show that compared with DT-DVTR,MTCR-CR reduces the number of routing changes by about 92%,the number of path changes caused by routing changes is about38%,and the rerouting time is reduced by approximately 47%.At the same time,in order to show our algorithm more comprehensively,the same experimental index test was also carried out on the Globalstar satellite constellation.

关键词： ISL routing stability satellite networks satellite routing dynamic strategy

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Improving the high cycle fatigue property of Ti6Al4V Eli alloy by optimizing the surface integrity through electric pulse combined with ultrasonic surface rolling process

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Journal of Materials Science & Technology 2024年第3期170卷 103-121页

作者： Pengfei sun Shengguan Qu Chenfeng Duan Xiongfeng Hu Xiaoqiang li National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials South China University of TechnologyGuangzhou 510640China School of Mechanical and Automotive Engineering South China University of TechnologyGuangzhou 510640China

To improve the surface integrity and high cycle fatigue property of Ti6Al4V Eli alloy,the electric pulse has been introduced into the ultrasonic surface rolling process(USRP),which is called electric pulse-assisted ultrasonic surface rolling process(EUSRP).With the help of“electroplasticity”of the electric pulse,the thickness of the surface gradient deformation layer was about three times of the USRP specimens by adjusting the pulse current ***,the surface hardness decreases due to the continuous effect of the pulse current and the“skin effect”during *** is worth noting that the higher the applied pulse current,the more severe the *** paradox causes the fatigue performance of EUSRP specimens lower than that of USRP *** break this paradox,the EUSRP treatment is followed by a USRP *** EUSRP-2(with a pulse current of 200 A)+USRP specimens exhibit excellent surface hardness,a gradient deformation layer thickness of about 400μm,low surface roughness and high compressive residual compressive ***,the hardening mechanisms of the different surface strengthening specimens have been quantitatively analyzed in combination with microstructure *** fatigue life of Ti6Al4V Eli alloy can be improved by about 25 times at 780 MPa using the EUSRP-2+USRP treatment,the main reason for the highest fatigue life is the deepest surface gradient layer and the deepest crack initiation *** fatigue limit of the EUSRP-2+USRP specimens is not the highest because too much surface hardening causes compressive residual stress relaxation during cycling and the beneficial effect of compressive residual stress is eliminated.

关键词： Ti6Al4V Eli alloy Combined surface treatment Transmission electron microscopy Residual stress Fatigue performance

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Recent advances in stretchable triboelectric nanogenerators for use in wearable bioelectronic devices

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Bio-Design and Manufacturing 2024年第4期7卷 566-590页

作者： Yaling Wang Pengcheng Zhu Yue sun Pan li Yanchao Mao College of Science Henan Agricultural UniversityZhengzhou 450002China Key Laboratory of Materials Physics of Ministry of Education School of PhysicsZhengzhou UniversityZhengzhou 450001China

Wearable bioelectronic devices have the capacity for real-time human health monitoring,the provision of tailored services,and natural interaction with smart ***,these wearable bioelectronic devices rely on conventional rigid batteries that are frequently charged or replaced and are incompatible with the skin,leading to a discontinuity in complex therapeutic tasks related to human health monitoring and human-machine *** triboelectric nanogenerator(TENG)is a high-efficiency energy harvesting technology that converts mechanical into electrical energy,effectively powering wearable bioelectronic *** study comprehensively overviews recent advances in stretchable TENG for use in wearable bioelectronic *** working mechanism of stretchable TENG is initially explained.A comprehensive discussion presents the approaches for fabricating stretchable TENG,including the design of stretchable structures and the selection of stretchable ***,applications of wearable bioelectronic devices based on stretchable TENG in human health monitoring(body movements,pulse,and respiration)and human-machine interaction(touch panels,machine control,and virtual reality)are ***,the challenges and developmental trends regarding wearable bioelectronic devices based on stretchable TENG are elaborated.

关键词： Stretchable Triboelectric nanogenerators Structure Human health monitoring Human-machine interaction

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A GMDA clustering algorithm based on evidential reasoning architecture

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Chinese Journal of Aeronautics 2024年第1期37卷 300-311页

作者： Haibin WANG Xin GUAN Xiao YI Shuangming li Guidong sun Naval Aviation University Yantai 264001China Unit 92941 of PLA Huludao 125001China Institute of Systems Engineering Beijing 100082China

The traditional clustering algorithm is difficult to deal with the identification and division of uncertain objects distributed in the overlapping region,and aimed at solving this problem,the Evidential Clustering based on General Mixture Decomposition Algorithm(GMDA-EC)is ***,the belief classification of target cluster is carried out,and the sample category of target distribution overlapping region is ***,on the basis of General Mixture Decomposition Algorithm(GMDA)clustering,the fusion model of evidence credibility and evidence relative entropy is constructed to generate the basic probability assignment of the target and achieve the belief division of the ***,the performance of the algorithm is verified by the synthetic dataset and the measured *** experimental results show that the algorithm can reflect the uncertainty of target clustering results more comprehensively than the traditional probabilistic partition clustering algorithm.

关键词： Evidential clustering Credal partition Evidential reasoning Mixed decomposition Gaussian mixture model

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Laser Doppler flowmeter study on regional cerebral blood flow in early stage after standard superficial temporal artery-middle cerebral artery bypass surgery for moyamoya disease

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Chinese Medical Journal 2009年第20期122卷 2412-2418页

作者： GESANG Dun-zhu ZHANG Dong ZHAO Ji-zong WANG Shuo ZHAO Yuan-li WANG rong sun Jian-jun MENG Ze Department of Neurosurgery Beijing Tiantan Hospital Capital Medical University Beijing 100050 China

Background Standard superficial temporal artery-middle cerebral artery （STA-MCA） bypass surgery is an effective treatment for moyamoya disease, but recent evidence suggests that postoperative cerebral hyperperfusion can occur. In this study, the trendline of changes in regional cerebral blood flow （rCBF） after surgery were continually monitored near the site of anastomosis in order to investigate both the efficacy of the procedure for improving rCBF and the possible risk of hyperperfusion . Methods Standard STA-MCA bypass surgery was performed on 13 patients, rCBF was measured continually using laser Doppler flowmetry （LDF） until the 5th day after the operation with the LDF probe implanted adjacent to the area of the anastomosis. The trendline of rCBF changes postoperatively was recorded for the analysis performed using SPSS 13.0. Results The baseline LDF value of cortical rCBF was （84.68±14.39） perfusion unit （PU）, which was linear relative to absolute perfusion volume before anastomosis and （88.90±11.26） PU immediately after anastomosis （P 〉0.05）. The value changed significantly from before to after anastomosis （P 〈0.05）; it was （417.72±21.35） PU on the 1st day after surgery, and （358.99±18.01） PU, （323.46±17.38） PU, （261.60±16.38） PU and （375.72±18.45） PU on the following 4 days, respectively. The rCBF decreased gradually from the 2nd day until the 4th postoperative day, but still was at a high level （P 〈0.05）. However, on the 5th postoperative day the rCBF increased again to the second highest level, which was significantly different compared with the baseline value （P 〈0.05）, but not significantly different compared with the values on the other 4 days （P〉0.05）. Conclusions STA-MCA anastomosis improves the cerebral blood supply significantly in the early stage after surgery, however, the risk of symptomatic hyperperfusion may exist, which may possibly occur on the 1st day and 5th day after surgery. A LDF is useful for postoperative monitoring for both the effica

关键词： moyamoya disease STA-MCA bypass laser-Doppler flowmetry regional cerebral blood flow

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