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Coupled effects of climate change and human activities on vegetation dynamics in the Southwestern Alpine Canyon Region of China

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Journal of Mountain Science 2024年第10期21卷 3234-3248页

作者： lai Jinlin QI Shi School of Soil and Water Conservation Beijing Forestry UniversityBeijing 100083China

The driving effects of climate change and human activities on vegetation change have always been a focal point of ***,the coupling mechanisms of these driving factors across different temporal and spatial scales remain *** Southwestern Alpine Canyon Region of China(SACR),as an ecologically fragile area,is highly sensitive to the impacts of climate change and human *** study constructed a vegetation cover dataset for the SACR based on the Enhanced Vegetation Index(EVI)from 2000 to *** autocorrelation,Theil-Sen trend,and Mann-Kendall tests were used to analyze the spatiotemporal characteristics of vegetation cover *** main drivers of spatial heterogeneity in vegetation cover were identified using the optimal parameter geographic detector,and an improved residual analysis model was employed to quantify the relative contributions of climate change and human activities to interannual vegetation cover *** main findings are as follows:Spatially,vegetation cover exceeds 60%in most areas,especially in the southern part of the study ***,the border area between Linzhi and Changdu exhibits lower vegetation *** factors are the primary drivers of spatial heterogeneity in vegetation cover,with temperature having the most significant influence,as indicated by its q-value,which far exceeds that of other ***,the interaction q-value between the two factors significantly increases,showing a relationship of bivariate enhancement and nonlinear *** terms of temporal changes,vegetation cover shows an overall improving trend from 2000 to 2020,with significant increases observed in 68.93%of the study *** these,human activities are the main factors driving vegetation cover change,with a relative contribution rate of 41.31%,while climate change and residual factors contribute 35.66%and 23.53%,*** thoroughly exploring the coupled mechanisms of vegetation change,this

关键词： Enhanced vegetation index Climate change Human activities Spatial heterogeneity Coupled mechanisms

Benchmarking visual SLAM methods in mirror environments

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Computational Visual Media 2024年第2期10卷 215-241页

作者： Peter Herbert Jing Wu Ze Ji Yu-Kun lai School of Computer Science and Informatics Cardiff UniversityAbacws BuildingSenghennydd RdCardiff CF244AGUK School of Engineering Cardiff UniversityQueen’s BuildingsThe ParadeCardiff CF243AAUK

Visual simultaneous localisation and mapping(vSLAM)finds applications for indoor and outdoor navigation that routinely subjects it to visual complexities,particularly mirror *** effect of mirror presence(time visible and its average size in the frame)was hypothesised to impact localisation and mapping performance,with systems using direct techniques expected to perform ***,a dataset,MirrEnv,of image sequences recorded in mirror environments,was collected,and used to evaluate the performance of existing representative *** ORB-SLAM3 and BundleFusion appear to show moderate degradation of absolute trajectory error with increasing mirror duration,whilst the remaining results did not show significantly degraded localisation *** mesh maps generated proved to be very inaccurate,with real and virtual reflections colliding in the reconstructions.A discussion is given of the likely sources of error and robustness in mirror environments,outlining future directions for validating and improving vSLAM performance in the presence of planar *** MirrEnv dataset is available at https://***/10.17035/d.2023.0292477898.

关键词： visual simultaneous localisation and mapping(vSLAM) mirror localisation mapping reflection datase

Enhanced Fenton-like process over Cu/L(+)-ascorbic acid co-doping mesoporous silica for toxicity reduction of emerging contaminants

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Frontiers of Environmental Science & Engineering 2024年第4期18卷 49-60页

作者： Yuhang Liu Wenxuan Deng Xiaojun Wu Chun Hu lai Lyu Key Laboratory for Water Quality and Conservation of the Pearl River Delta(Ministry of Education) Institute of Environmental Research at Greater BayGuangzhou UniversityGuangzhou 510006China

Effective removal of emerging contaminants(ECs)to minimize their impacts on human health and the natural environment is a global *** the removal of ECs in water,we fabricated a seaweed spherical microsphere catalyst with Cu cation-πstructures by in situ doping of Cu species and ascorbic acid in mesoporous silica(Cu-C-MSNs)via a hydrothermal *** results indicate that bisphenol A(BPA)is substantially degraded within 5 min under natural conditions,with its biological toxicity considerably ***,industrial wastewater could also be effectively purified by Cu-C-MSNs/H_(2)O_(2) *** presence of metal sites and the complexation of ECs via cation-πinteraction andπ-πstacking on the catalyst surface were directly responsible for the polarization distribution of electrons,thus activating H_(2)O_(2) and dissolved oxygen(DO).The removal of contaminants could be attributed primarily to 1)the activation of H_(2)O_(2) into ^(·)OH to attack the contaminants and 2)self-cleavage because of the transfer of electrons from the contaminants to the *** study provides an innovative solution for the effective treatment of ECs and has positive implications for easing global environmental crises.

关键词： Cation-πstructures Polarization electric field Fenton-like process Contaminants cleavage

Non-uniform thermal behavior of single-layer spherical reticulated shell structures considering time-variant environmental factors: analysis and design

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第3期25卷 223-237页

作者： Wucheng XU Xiaoqing ZHENG Xuanhe ZHANG Zhejie lai Yanbin SHEN College of Civil Engineering and Architecture Zhejiang UniversityHangzhou 310058China Center for Balance Architecture Zhejiang UniversityHangzhou 310028China Innovation Center of Yangtze River Delta Zhejiang UniversityJiaxing 314100China Zhejiang Provincial Key Laboratory of Space Structures Zhejiang UniversityHangzhou 310058China

Contrary to conventional design methods that assume uniform and slow temperature changes tied to atmospheric conditions,single-layer spherical reticulated shells undergo significant non-uniform and time-variant temperature variations due to dynamic environmental *** differences can affect structural performance and pose safety ***,a systematic numerical method was developed and applied to simulate long-term temperature variations in such a structure under real environmental conditions,revealing its non-uniform distribution characteristics and time-variant regularity.A simplified design method for non-uniform thermal loads,accounting for time-variant environmental factors,was theoretically derived and validated through experiments and *** maximum deviation and mean error rate between calculated and tested results were 6.1℃ and 3.7%,*** temperature fields aligned with simulated ones,with deviations under 6.0℃.Using the design method,non-uniform thermal effects of the structure are *** member stress and nodal displacement under non-uniform thermal loads reached 119.3 MPa and 19.7 mm,representing increases of 167.5%and 169.9%,respectively,compared to uniform thermal *** impacts of healing construction time on non-uniform thermal effects were evaluated,resulting in construction *** methodologies and conclusions presented here can serve as valuable references for the thermal design,construction,and control of single-layer spherical reticulated shells or similar structures.

关键词： Non-uniform temperature field Non-uniform thermal load Non-uniform thermal effect Single-layer spherical reticulated shell Time-variant environmental factor

Alkylene-functionality in bridged and fused nitrogen-rich poly-cyclic energetic materials:Synthesis,structural diversity and energetic properties

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Defence Technology（防务技术） 2024年第5期35卷 18-46页

作者： Man Xu Nanxi Xiang Ping Yin Qi lai Siping Pang School of Materials Science&Engineering Beijing Institute of TechnologyBeijing 100081China Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China

From the standpoint of chemical structures,the organic backbones of energetic materials can be classified into aromatic rings,nonaromatic rings,and open *** the category of aromatic energetic compounds exhibits several advantages in the regulation of energetic properties,the nonaromatic heterocycles,assembling nitramino explosophores with simple alkyl bridges,still have prevailed in benchmark *** methylene bridge plays a pivotal role in the constructions of the classic nonaromatic heterocycle-based energetic compounds,e.g.,hexahydro-1,3,5-trinitro-1,3,5-triazine(RDX)and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX),whereas ethylene bridge is the core moiety of state-of-the-art explosive 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20).In this context,it is of great interest to employ simple and practical bridges to assemble aromatic and nonaromatic nitrogen-rich heterocycles,thereby expanding the structural diversity of energetic materials,e.g.,bridged and fused nitrogen-rich ***,alkyl-bridged poly-heterocycles highlight the potential for the open chain type of energetic *** this review,the development of alkyl bridges in linking nitrogen-rich heterocycles is presented,and the perspective of the newly constructed energetic backbones is summarized for the future design of advanced energetic materials.

关键词： Energetic materials Alkyl bridge strategy Nitrogen-rich azoles Fused heterocycles Azoles

Dynamics and vibration reduction performance of asymmetric tristable nonlinear energy sink

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Applied Mathematics and Mechanics(English Edition) 2024年第3期45卷 389-406页

作者： Hongyan CHEN Youcheng ZENG Hu DING Siukai lai Liqun CHEN School of Mechanical Engineering University of Science and Technology BeijingBeijing 100083China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Frontier Science Center of MechanoinformaticsShanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200444China Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityKowloonHong KongChina

With its complex nonlinear dynamic behavior,the tristable system has shown excellent performance in areas such as energy harvesting and vibration suppression,and has attracted a lot of *** this paper,an asymmetric tristable design is proposed to improve the vibration suppression efficiency of nonlinear energy sinks(NESs)for the first *** proposed asymmetric tristable NES(ATNES)is composed of a pair of oblique springs and a vertical ***,the three stable states,symmetric and asymmetric,can be achieved by the adjustment of the distance and stiffness asymmetry of the oblique *** governing equations of a linear oscillator(LO)coupled with the ATNES are *** approximate analytical solution to the coupled system is obtained by the harmonic balance method(HBM)and verified *** vibration suppression efficiency of three types of ATNES is *** results show that the asymmetric design can improve the efficiency of vibration reduction through comparing the chaotic motion of the NES oscillator between asymmetric steady *** addition,compared with the symmetrical tristable NES(TNES),the ATNES can effectively control smaller structural *** other words,the ATNES can effectively solve the threshold problem of TNES failure to weak ***,this paper reveals the vibration reduction mechanism of the ATNES,and provides a pathway to expand the effective excitation amplitude range of the NES.

关键词： asymmetric nonlinear energy sink(NES) tristable vibration control po-tential barrier

Mechanical property of cylindrical sandwich shell with gradient core of entangled wire mesh

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Defence Technology（防务技术） 2024年第1期31卷 510-522页

作者： Xin Xue Chao Zheng Fu-qiang lai Xue-qian Wu Institute of Metal-rubber&Vibration Noise School of Mechanical Engineering and AutomationFuzhou UniversityFuzhou350116China Fujian Metallurgical Industry Design Institute Fuzhou350116China

To explore the wide-frequency damping and vibration-attenuation performances in the application of aerospace components,the cylindrical sandwich shell structure with a gradient core of entangled wire mesh was proposed in this ***,the gradient cores of entangled wire mesh in the axial and radial directions were prepared by using an in-house Numerical Control weaving machine,and the metallurgical connection between skin sheets and the gradient core was performed using vacuum ***,to investigate the mechanical properties of cylindrical sandwich shells with axial or radial gradient cores,quasi-static and dynamic mechanical experiments were carried *** primary evaluations of mechanical properties include secant stiffness,natural frequency,Specific Energy Absorption(SEA),vibration acceleration level,and so *** results suggest that the vibration-attenuation performance of the sandwich shell is remarkable when the high-density core layer is at the end of the shell or abuts the inner *** axial gradient material has almost no influence on the vibration frequencies of the shell,whereas the vibration frequencies increase dramatically when the high-density core layer approaches the ***,compared to the conventional sandwich shells,the proposed functional grading cylindrical sandwich shell exhibits more potential in mass reduction,stiffness designing,and energy dissipation.

关键词： Entangled wire mesh Gradient cylindrical sandwich shell Vacuum brazing Secant stiffness Damping

A booming field of large animal model research

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Zoological Research 2024年第2期45卷 311-313页

作者： Xiao-Jiang Li Liangxue lai Guangdong Key Laboratory of Non-human Primate Research Key Laboratory of CNS Regeneration(Ministry of Education)GHM Institute of CNS RegenerationJinan UniversityGuangzhouGuangdong 510632China State Key Laboratory of Bioactive Molecules and Druggability Assessment Jinan UniversityGuangzhouGuangdong 510632China CAS Key Laboratory of Regenerative Biology Guangdong Provincial Key Laboratory of Stem Cell and Regenerative MedicineGuangzhou Institutes of Biomedicine and HealthChinese Academy of SciencesGuangzhouGuangdong 510530China

Animal models are integral to the study of fundamental biological processes and the etiology of human *** animal models,especially those involving mice,have yielded abundant and significant insights,greatly enhancing ... 详细信息

关键词： mechanisms insight field

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网架模型日照非均匀温度场试验

哈尔滨工业大学学报 2018年第1期50卷 191-198页

作者：王化杰陈友钱宏亮金晓飞来佳琪哈尔滨工业大学(威海)土木工程系山东威海264209 哈尔滨工业大学土木工程学院哈尔滨150090 中国联合工程公司杭州310052 中建一局集团公司总承包公司北京100161

为得到日照下空间钢结构非均匀温度场分布规律,给现有非均匀温度场模拟方法提供标准、可靠的试验验证依据,设计并制作了标准的三角形平板网架模型,对其均匀温度场试验进行了详细设计,完成了不同环境下三角形平板网架非均匀温度场的连续... 详细信息

为得到日照下空间钢结构非均匀温度场分布规律,给现有非均匀温度场模拟方法提供标准、可靠的试验验证依据,设计并制作了标准的三角形平板网架模型,对其均匀温度场试验进行了详细设计,完成了不同环境下三角形平板网架非均匀温度场的连续测量,得到了较为全面的网架结构非均匀温度场试验数据,并对其进行了详细分析,结果表明,网架结构杆件水平放置时,摆放角度对杆件温度变化影响不大,非水平放置时,摆放角度影响较大,不同杆件间温差最大可达13℃,网架模型非均匀温度场效应明显;最后建立了三角形平板网架非均匀温度场有限元分析模型,采用考虑阴影的数值模拟方法对试验进行模拟分析,并将模拟结果与实测结果进行对比,试验结果与数值模拟结果基本相同,全天平均误差率不超过6%.考虑阴影遮挡的非均匀温度场模拟方法可用于结构非均匀温度场分析,模型试验可为同类非均匀温度场模拟方法提供验证依据.

关键词：钢结构网架模型试验研究非均匀温度场摆放角度