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Integrating Factors and Conservation Theorems for the Nonholonomic Singular Lagrange System

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Communications in Theoretical Physics 2007年第5X期48卷 791-794页

作者： zhao shu-hong liang li-Fu QIAO Yong-Fen school of civil engineering of harbin engineering university Harbin 150001 China engineering college of northeast agricultural university Harbin 150030 China

We present a general approach to the construction of conservation laws for the nonholonomic singular Lagrange system. Firstly, the differential equations of motion of the system are written, the definition of integrating factors is given for the system. Next, the necessary conditions for the existence of the conserved quantity are studied in detail. Finally, the conservation theorem and its inverse are established for the system, an example is given to illustrate the application of the result.

关键词： analytical mechanics singular system integrating factor conserved quantity

节理倾角对类岩石冲击能量传递影响的试验研究

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中南大学学报（自然科学版） 2018年第5期49卷 1237-1243页

作者：王建国梁书锋高全臣李祥龙王立娜赵炎云南农业大学建筑工程学院云南昆明650201 中国矿业大学(北京)力学与建筑工程学院北京100083 昆明理工大学国土资源与工程学院云南昆明650093

用砂浆材料模拟不同倾角的节理岩石试件,并借助霍普金森压杆试验系统(SHPB)装置对其进行相似速度下的冲击试验,研究节理倾角对应力波穿越节理面时的波动特性和能量传递及耗散的影响,并给出能量耗散比随节理倾角变化的表达式。研究结果表... 详细信息

用砂浆材料模拟不同倾角的节理岩石试件,并借助霍普金森压杆试验系统(SHPB)装置对其进行相似速度下的冲击试验,研究节理倾角对应力波穿越节理面时的波动特性和能量传递及耗散的影响,并给出能量耗散比随节理倾角变化的表达式。研究结果表明:在相似入射能量条件下,随着节理角度增大,反射能量比ER/EI(即反射波能量ER与入射波能量EI之比)先增大后减小,透射能量比ET/EI(即透射波能量ET与入射波能量EI之比)先减小后增大,且在节理倾角等于破坏角时,反射能量比和透射能量比到达极值;能量耗散比ED/EI(即节理试件耗散能量ED与入射波能量EI之比)随节理倾角的变化有所波动,分别在倾角为30°和90°时取得2个极大值。

关键词：节理倾角节理岩石 SHPB 应力波能量耗散

Taking the pulse of COVID-19:a spatiotemporal perspective

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International Journal of Digital Earth 2020年第10期13卷 1186-1211页

作者： Chaowei Yang Dexuan Sha Qian liu Yun li Hai Lan Weihe Wendy Guan Tao Hu Zhenlong li Zhiran Zhang John Hoot Thompson Zifu Wang David Wong Shiyang Ruan Manzhu Yu Douglas Richardson Luyao Zhang Ruizhi Hou You Zhoua Cheng Zhong Yifei Tian Fayez Beaini Kyla Carte Colin Flynn Wei liu Dieter Pfoser shuming Bao Mei li Haoyuan Zhang Chunbo liu Jie Jiang Shihong Du liang zhao Mingyue Lu lin li Huan Zhou Andrew Ding NSF Spatiotemporal Innovation Center George Mason Univ.FairfaxVAUSA Department of Geography and GeoInformation Science George Mason Univ.FairfaxVAUSA Department of Geographical Sciences University of MarylandCollege ParkMDUSA Center for Geographic Analysis Harvard UniversityCambridgeMAUSA Geoinformation and Big Data Research Lab Department of GeographyUniversity of South CarolinaColumbiaSCUSA Chinese Academy of Surveying and Mapping BeijingPeople’s Republic of China school of Resource and Environmental Sciences Wuhan UniversityWuhanPeople’s Republic of China Cloud Computeand Storage OperationsInformation Technology ServicesGeorge Mason UniversityFairfaxVAUSA Department of Geography Pennsylvania State UniversityState CollegePAUSA school of Business Management East China Normal UniversityShanghaiPeople’s Republic of China school of Mathematical Sciences East China Normal UniversityShanghaiPeople’s Republic of China Department of Psychology George Mason UniversityFairfaxVAUSA mDepartment of Computer Science George Mason UniversityFairfaxVAUSA Department of Information Technology George Mason UniversityFairfaxVAUSA Department of Biology George Mason UniversityFairfaxVAUSA college of Land Science and Technology China Agricultural UniversityBeijingPeople’s Republic of China china Data Institute Ann ArborMIUSA Institute of Remote Sensing and GIS Peking UniversityBeijingPeople’s Republic of China Aerospace Information Research Institute Chinese Academy of SciencesBeijingPeople’s Republic of China school of Geomatics and Urban Spatial Informatics Beijing University of Civil Engineering and ArchitectureBeijingPeople’s Republic of China school of Geographical Sciences Nanjing University of Information Science&TechnologyNanjingPeople’s Republic of China school of Geodesy and Geomatics Wuhan UniversityWuhanPeople’s Republic of China wFaculty of Environment University of WaterlooWaterlooCanada

The sudden outbreak of the Coronavirus disease(COVID-19)swept across the world in early 2020,triggering the lockdowns of several billion people across many countries,including china,Spain,India,the U.K.,Italy,France,Germany,Brazil,Russia,and the *** transmission of the virus accelerated rapidly with the most confirmed cases in the U.S.,India,Russia,and *** response to this national and global emergency,the NSF Spatiotemporal Innovation Center brought together a taskforce of international researchers and assembled implementation strategies to rapidly respond to this crisis,for supporting research,saving lives,and protecting the health of global *** perspective paper presents our collective view on the global health emergency and our effort in collecting,analyzing,and sharing relevant data on global policy and government responses,human mobility,environmental impact,socioeconomical impact;in developing research capabilities and mitigation measures with global scientists,promoting collaborative research on outbreak dynamics,and reflecting on the dynamic responses from human societies.

关键词： Big Data Earth system emergency geospatial sciences epidemics applications

Toward a sustainable grassland ecosystem worldwide

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The Innovation 2022年第4期3卷 15-16页

作者： Jian Sun Yi Wang Shilong Piao Miao liu Guodong Han Junran li Eryuan liang Tien Ming Lee Guohua liu Andreas Wilkes Shiliang liu Wenwu zhao Huakun Zhou Mesenbet Yibeltal Mulatu liyew Berihun Dawn Browning Ayele Almaw Fenta Atsushi Tsunekawa Joel Brown Walter Willms Mitsuru Tsubo State Key Laboratory of Earth System Resources and Environment of Tibetan Plateau Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China school of life Sciences and school of Ecology State Key Lab of Biological ControlSun Yat-sen UniversityGuangzhou 510275China Sino-French Institute for Earth System Science College of Urban and Environmental SciencesPeking UniversityBeijing 100871China college of Grassland Science and Technology China Agricultural UniversityBeijing 100193China Key Laboratory of Grassland Resources of the Ministry of Education College of GrasslandResources and EnvironmentInner Mongolia Agricultural UniversityHohhot 010011China Department of Geosciences The University of TulsaTulsaOK 74137USA State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China Values for Development Ltd Bury St.Edmunds IP333EQUK school of Environment Beijing Normal UniversityBeijing 100875China Faculty of Geographical Science Beijing Normal UniversityBeijing 100875China Key Laboratory of Restoration Ecology for Cold Regions in Qinghai Northwest Institute of Plateau BiologyChinese Academy of SciencesXining 810008China Faculty of civil and Water Resource engineering Bahir Dar Institute of TechnologyBahir Dar UniversityBahir DarEthiopia Arid Land Research Center Tottori UniversityTottori 6800001Japan USDA–ARS Jornada Experimental Range Las CrucesNM 88003USA USDA NRCS Jornada Experimental RangeNew Mexico State UniversityMSC 3JERPO Box 30003Las CrucesNMUSA Agriculture and Agri-Food Canada Lethbridge Research Centre54031st Avenue SouthLethbridgeABCanada

Globally,grasslands,covering about 40%of the Earth’s land area,are vital for supporting important ecosystem functions,services,and livelihoods of millions of ***,grassland degradation is a major threat to the maintenance of ecological services,1 food security,and sustainable development,and directly hinders the global efforts with meeting goals and targets such as the The UN Decade on Ecosystem Restoration and Sustainable Development Goals(SDGs).Remote sensing approaches have the advantages of spanning large geographical areas withmultiple spatial,spectral,and temporal *** global scale,remote sensing methods used normalized difference vegetation index to determine net primary productivity(NPP),which still is the effectivemethod to indicate grassland *** master the general situation of grassland,we analyzed the global spatial-temporal variation of NPP from 2001 to 2019 at the pixel level across the *** presented in Figure 1A,the NPP values of global grasslands showed an obvious variation trend,which indicated a considerable distribution pattern of spatial *** decreasing and increasing trend in grassland NPP covered approximately 25.3%and 74.5%of the total grassland area,respectively.

关键词： grassland Figure hinder

土木工程专业生产实习自主过程管理教学改革实践研究

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沈阳建筑大学学报（社会科学版） 2021年第5期23卷 531-535页

作者：赵亮吴红爽李兵沈阳建筑大学土木工程学院辽宁沈阳110168 沈阳农业大学水利学院辽宁沈阳110866

生产实习作为土木工程专业重要的实践环节,对于培养学生实践能力、创新能力以及发现、分析、解决复杂工程问题能力至关重要。由于学生对实习重要性认识不充分、实习广度和深度略显不足、过程指导不充分、考核不全面等问题,导致生产实习... 详细信息

生产实习作为土木工程专业重要的实践环节,对于培养学生实践能力、创新能力以及发现、分析、解决复杂工程问题能力至关重要。由于学生对实习重要性认识不充分、实习广度和深度略显不足、过程指导不充分、考核不全面等问题,导致生产实习效果不佳。针对这些问题,应完善实习系统、加强实习动员、引导学生自主管理、强化过程管理、完善考核方法,切实做好生产实习工作,为社会和企业输送合格的土木工程专业人才。

关键词：土木工程专业生产实习自主管理过程管理创新能力