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Identification and spatial pattern analysis of alpine timberline by remote sensing methods in Yarlung Zangpo Grand Canyon

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Journal of Mountain Science 2021年第9期18卷 2304-2314页

作者： ZHU Bei WANG Shi-yan SU Wei CHEN Kai-qi LIU Chang DU Yan-liang WANG Liang HAN Zhen zou jiang-xiang State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin Beijing 100038China China Institute of Water Resources and Hydropower Research Beijing 100038China College of Hebei Agricultural University Huanghua 061100China Appraisal Center for Environment and Engineering Ministry of Environmental ProtectionBeijing 100012China

As an important ecotone,the alpine timberline is the boundary between closed-canopy montane forest and alpine vegetation,and is highly sensitive to global and regional climate *** provided a way to identify and extract the alpine timberline in Yarlung Zangpo Grand Canyon Nature Reserve by using remote sensing data and spatial analysis based on land use/land cover classification and NDVI distribution *** DEM data,the influence of slope and aspect on the distribution of alpine timberline was *** results showed that the alpine timberline in Yarlung Zangpo Grand Canyon is transitional timberline,with the upper boundary approximately distributed at the elevation of 3422-4373 m,the lower boundary at approximately 3270-4164 m,with a width of about 110-280 *** timberline was mainly distributed on steep and very steep slopes ranging from 25°to 45°.The maximum elevation of both the upper and lower boundaries occurred on steep *** distribution of alpine timberline varies with aspects,with sunny slopes having a higher boundary than shady slopes.

关键词： Alpine timberline Aspect Normalized Difference Vegetation Index Remote sensing classification Slope

Voidage correction method for DEM study of 3D pebble flows in a bed of cycloidal base

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PARTICUOLOGY 2024年第10期93卷 30-40页

作者： Xia, Zirui Shi, Minglei zou, Quan Gui, Nan Yang, Xingtuan Tu, Jiyuan jiang, Shengyao Tsinghua Univ Inst Nucl & New Energy Technol Collaborat Innovat Ctr Adv Nucl Energy Technol Key Lab Adv Reactor Engn & SafetyMinist Educ Beijing 100084 Peoples R China Tsinghua Univ Dept Engn Phys Beijing 100084 Peoples R China Tsinghua Univ Dept Automat Beijing 100084 Peoples R China RMIT Univ Sch Engn Melbourne Vic 3083 Australia

Voidage (porosity or void fraction) in packed particles (or pebbles) is of fundamental importance in calculating the pressure drop, obtaining the drag, predicting the bed permeability, estimating the neutron streaming, etc. For the case when particles are deformed, a method of voidage correction during the packing state is proposed using a Discrete Element Method (DEM) simulation of 3D pebble flow inside a bed of cycloidal base. A function to evaluate the remaining volume of a pebble intercepted by horizontal and vertical planes is proposed for voidage calculation. After that, the process of solving voidage distribution is provided in detail. Using this method, the voidage inside the cycloidal-base pebble bed is obtained to refer to reported similar data for validation. This method can be potentially used for dynamical voidage calculation in CFD-DEM simulation which can get suitable voidage distribution after the correction. (c) 2024 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

关键词： Voidage Pebble flow Packed bed Discrete element method Cycloidal base KD-Tree Volume correction RADIAL POROSITY GAS MODEL SIMULATION PACKINGS SPHERES

Understanding the spatial interaction of ultrasounds based on three-dimensional dual-frequency ultrasonic field numerical simulation

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China Foundry 2024年第1期21卷 29-43页

作者： Zhao-yang Yin Qi-chi Le Yan-chao jiang Da-zhi Zhao Qi-yu Liao Qi zou Key Lab of Electromagnetic Processing of Materials Ministry of EducationNortheastern UniversityShenyang 110819China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China

A transient 3D model was established to investigate the effect of spatial interaction of ultrasounds on the dual-frequency ultrasonic field in magnesium alloy *** effects of insertion depth and tip shape of the ultrasonic rods,input pressures and their ratio on the acoustic field distribution were discussed in ***,the spacing,angle,and insertion depth of two ultrasonic rods significantly affect the interaction between distinct *** a result,various acoustic pressure distributions and cavitation regions are *** spherical rods mitigate the longitudinal and transversal attenuation of acoustic pressure and expand the cavitation volume by 53.7%and 31.7%,respectively,compared to the plate and conical *** the input pressure will enlarge the cavitation region but has no effect on the acoustic pressure distribution *** acoustic pressure ratio significantly affects the pressure distribution and the cavitation region,and the best cavitation effect is obtained at the ratio of 2:1(P15:P20).

关键词： dual-frequency ultrasonic numerical model acoustic pressure spatial interaction magnesium alloy

Research on the Dynamic Compressibility of Polyurethane Microcellular Elastomer and its Application for Impact Resistance

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Chinese Journal of Polymer Science 2024年第8期42卷 1185-1197页

作者： Zhi-Ying Zhao Hao jiang Xiao-Dong Li Xu-Dong Zhang Xing Su Mei-Shuai zou School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China

The packaging materials with cushioning performance are used to prevent the internal contents from being damaged by the impact and vibration of external *** polyurethane microcellular elastomers(PUMEs)can absorb energy through cell collapse and molecular chain *** this study,PUMEs with different densities were investigated by scanning electron microscopy,dynamic mechanical analysis and dynamic compression *** exhibited significant im pact resistance and the maximum peak stress attenuation ratio reached 73.33%.The protective equipment was made by PUME with the optimal density of 600 kg/m^(3),and then the acceleration sensing device installed with the same protective equipment fell from a height of 3,5 and 10 m to evaluate the energy-absorbing property and reusability of *** results showed that PUMEs equipment reduced the peak acceleration of the device by 93.84%,with a maximum deviation of 9%between actual test and simulation,and shortened the impact time of first landing by 57.39%.In addition,the equipment PUMEs equipment could effectively reduce the stress on the protected items.

关键词： Polyurethane microcellular elastomer Impact velocity Stress attenuation ratio Impact resistance

Promoting Vasa Vasorum Neovascularization of Vein Grafts Extenuates Hypoxia of the Wall and Its Subsequent Influence on Intimal Hyperplasia

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Chinese Medical Journal 2017年第11期130卷 1327-1332页

作者： Rong-jiang zou Zheng-Hua Wang Chen-Xi Wang Song Xue Department of Cardiovascular Surgery Ren Ji Hospital School of Medicine Shanghai Jiao Tong University Shanghai 200127 China

Background： The autologous saphenous vein is the most common conduit for coronary artery bypass grafting, but the vein graft disease will occur. This study used Matrigel basement membrane matrix with many different growth factors to promote vasa vasorum neovascularization and extenuate the hypoxia to improve remodeling. Methods： This study observed the hypoxia and thickness of the vein grafts at different times. Normal veins and vein grafts with 15 min ofischemia one day postoperatively were harvested in the neck of rabbits. Paired vein grafts with 15 min ischemia bilaterally （control vs. Matrigel basement membrane matrix） were performed and harvested at 2, 6, and 12 weeks postoperatively. The rabbits were randomly divided into four postoperative groups （six rabbits in each group）： Group 1, one day postoperatively; Group 2, 2 weeks postoperatively; Group 3, 6 weeks postoperatively; and Group 4, 12 weeks postoperatively. The dimensions of vessel wall were captured, and the mean thicknesses of intima, media, and adventitia were measured. The hypoxia-inducible factor （HIF）- 1α and HIF-2ot labeling indices ofintima, media, and adventitia were also measured. Results： In Group 1, the labeling index of HIF-1α was high in the normal vein and decreased significantly in the vein grail one day postoperatively （intima： 80 4- 3% vs. 12 4- 1%, P = 0.01 ; media： 67 ±5% vs. 11 ± 1%, P = 0.01 ; adventitia： 40 ± 10% vs. 7 ±2%, P = 0.03）. The labeling index of HIF-2α had similar trend as HIF-1α （intima： 80 ± 10% vs. 10 ± 5%, P = 0.02; media： 60± 14% vs. 12 ± 2%, P = 0.01 ; adventitia： 45±20% vs. 10±4%, P = 0.03）. Compared with the control vein gratrol vein grafts with Matrigel basement membrane matrix had lower labeling indices of HIF-1α and HIF-2α in media and adventitia at Group 2 （HIF-1α： 34 ± 5% vs. 20 ±4%, P = 0.04 for media： 23 ± 3% vs. 11 ± 2%, P = 0.03 for adventitia; HIF-2α： 37 ± 6% vs. 21 ± 4%, P = 0.03 for media; 24 ±4% vs. 13 ± 2%, P = 0.04 for adventitia） and Group 3 （HIF

关键词： Hypoxiaz Hypoxia-inducible Factor lntimal Hyperplasia Vein Graft

Healing the structural defects of spinel MnFe2O4 to enhance the electrocatalytic activity for oxygen reduction reaction

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Journal of Energy Chemistry 2024年第10期97卷 12-19页

作者： Manting Tang Yue zou Zhiyong jiang Peiyu Ma Zhiyou Zhou Xiaodi Zhu Jun Bao Shi-Gang Sun National Synchrotron Radiation Laboratory University of Science and Technology of China State Key Laboratory of Physical Chemistry of Solid Surfaces Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University iChEM (Collaborative Innovation Center of Chemistry for Energy Materials) University of Science and Technology of China

Spinel metal oxides containing Mn,Co,or Fe（AB2O4,A/B=Mn/Fe/Co） are one of the most promising nonPt electrocatalysts for oxygen reduction reaction（ORR） in alkaline ***,the low conductivity of metal oxides and the poor intrinsic activities of transition metal sites lead to unsatisfactory ORR *** this study,eutectic molten salt（EMS） treatment is employed to reconstruct the atomic arrangement of MnFe2O4electrocatalyst as a prototype for enhancing ORR *** analyses by using XAFS,soft XAS,XPS,and electrochemical methods reveal that the EMS treatment reduces the oxygen vacancies and spinel inverse in MnFe2O4effectively,which improves the electric conductivity and increases the population of more catalytically active Mn2+sites with tetrahedral ***,the enhanced Mn-O interaction after EMS treatment is conducive to the adsorption and activation of O2,which promotes the first electron transfer step（generally considered as the ratedetermining step） of the ORR *** a result,the EMS treated MnFe2O4catalyst delivers a positive shift of 40 mV in the ORR half-wave potential and a two-fold enhanced mass/specific *** work provides a convenient approach to manipulate the atomic architecture and local electronic structure of spinel oxides as ORR electrocatalysts and a comprehensive understanding of the structureperformance relationship from the molecular/atomic scale.

关键词： Eutectic molten salt Oxygen reduction reaction Oxygen vacancies Spinel inverse Spinel MnFe2O4

Process-driven susceptibility assessment of glacial lake outburst debris flow in the Himalayas under climate change

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Advances in Climate Change Research 2024年第3期15卷 500-514页

作者： Bin ZHOU Qiang zou Hu jiang Tao YANG Wen-Tao ZHOU Si-Yu CHEN Hong-Kun YAO Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China University of Chinese Academy of Sciences Beijing 100049China School of Environment and Resource Southwest University of Science and TechnologyMianyang 621010China

Global warming is causing glaciers to retreat and glacial lakes to expand in the Himalayas,which amplifies the risk of glacial lake outburst debris flows(GLODFs)and poses a significant threat to downstream lives and ***,the complex interplay between GLODF occurrences and associated indicators,coupled with the lack of a comprehensive susceptibility indicator system that considers the entire GLODF process,presents a substantial challenge in assessing GLODF susceptibility in the *** study proposes a process-driven GLODF susceptibility assessment indicator system responding to climate change that considers the complete process of GLODF formation,incorporating relevant parameters about upstream,themselves,and downstream of glacial ***,to mitigate subjective factors associated with traditional evaluation methods,we developed three novel hybrid machine-learning models by integrating classic machine-learning algorithms with the whale optimization algorithm(WOA)to delineate the distribution of GLODF susceptibility in the *** the hybrid models effectively predicted the GLODFs occurrence,with the WOA-SVC model demonstrating the highest prediction *** 34%of the catchments exhibit high and very high susceptibility levels,primarily concentrated along the north and south sides of the Himalayan ridge,particularly in the eastern and central *** capturing the physical formation process of hazards,such as topographic potential(highest relative importance value of 40%),can precisely identify GLODF.A total of 128 catchments pose potential transboundary threats,with 24 classified as having a very high susceptibility level and 25 as having a high susceptibility ***,the border region between China and Nepal is a prominent hotspot for transboundary threats of *** findings can provide valuable clues for disaster prevention,mitigation,and cross-border coordination in the Himalayas.

关键词： Glacial lake outburst debris flow Susceptibility assessment Climate change Himalayas

Tuning the membrane rejection behavior by surface wettability engineering for an effective water-in-oil emulsion separation

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Chinese Chemical Letters 2024年第6期35卷 480-485页

作者： Yan zou Yin-Shuang Hu Deng-Hui Tian Hong Wu Xiaoshu Lv Guangming jiang Yu-Xi Huang Engineering Research Center for Waste Oil Recovery Technology and Equipment Ministry of EducationChongqing Technology and Business UniversityChongqing 400067China School of Environmental Science and Engineering Sun Yat-sen UniversityGuangzhou 510275China Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology(Sun Yat-sen University) Guangzhou 510275China

Membrane-based separation is a promising technology to eliminate water impurities from the oil ***,it remains a great challenge to separate water from highly emulsified viscous oil owing to the high stability of the water droplets in *** we report a surface wettability engineering on an alumina ceramic membrane to achieve an efficient separation of a water-in-oil(W/O)*** with different carbon chain lengths and fluorinated status were introduced to endow the alumina membrane with different surface *** all the modified membranes exhibited excellent separation of the W/O without Span 80(surfactant),the one with amphiphobic wettability and lowest surface energy failed to separate the Span 80 stabilized W/*** presence of Span 80 reduced the interfacial tension of water droplets,making them easier to deform and penetrate the modified membrane with the lowest surface *** reveals that engineering proper surface wettability is the key to separating the oil and water ***,the modified membranes maintained decent separation performance and stability under long-term run separation of the emulsified W/O.

关键词： Water-in-oil emulsion Ceramic membrane Membrane separation Surface wettability

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超高强度弹簧钢冷变形性能及其仿真模拟

钢铁研究学报 2020年第12期32卷 1157-1164页

作者：邹江河姜云贵州大学机械工程学院贵州贵阳520025 贵阳学院机械工程学院贵州贵阳520005

针对60Si2CrVAT超高强度弹簧钢实际冷卷成形工况,采用准静态拉伸试验和不同微观表征手段研究了经Q&T (Quenching&Tempering)和Q-I-Q-T(Quenching-Isthothermal-Quenching-Tempering)工艺热处理后试验钢的组织形貌及冷变形前后力学性能的差异,并利用Deform-3D有限元数值模拟软件分析了2种工艺参数下的弹簧钢在冷卷成形过程中的应力、应变等场量参数的变化特征,预测了其冷卷成形过程中的断裂损伤概率。结果表明,Q-I-Q-T工艺复相组织弹簧钢的塑性更好,冷变形后的断面收缩率和伸长率比Q&T工艺马氏体中温回火组织弹簧钢分别高出了65%和66%。模拟结果显示,不同组织状态下的超高强度弹簧钢在卷制过程中的等效应力和等效应变分布规律近似,但Q-I-Q-T工艺复相组织弹簧钢在卷制过程中产生的等效应力和等效应变值更小,产生断裂的概率更低。

关键词：冷卷成形 60Si2CrVAT弹簧钢 Deform-3D模拟断裂损伤