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Land-use induced changes in topsoil organic carbon stock of paddy fields using MODIS and TM/ETM analysis:A case study of Wujiang County,China

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Journal of Environmental Sciences 2008年第7期20卷 852-858页

作者： GAO, Jianfeng PAN, Genxing JIANG, Xiaosan PAN, Jianjun ZHUANG, Dafang institute of Resources Ecosystem and Environment of Agriculture Nanjing Agricultural University Nanjing 210095 China institute of Geographical Science and Natural Resources Chinese Academy of Sciences Beijing 100101 China

Topsoil soil organic carbon (SOC) that plays an important role in mitigating atmospheric carbon dioxide (CO_2) buildup is greatly affected by human *** evaluate the influence of land-use changes on SOC stocks in paddy soils,a new algorithm was developed by integrating MODIS (moderate resolution imaging spectral-radiometer) and TM/ETM data for timely monitoring the land-use change in Wujiang ***,the land-use class-maps derived from MODIS and TM/ETM analyses were further used to estima...

关键词： soil organic carbon (SOC) MODIS TM/ETM rice paddies land-use soil C sequestration

Lee–Yang zeros in the Rydberg atoms

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Frontiers of physics 2023年第2期18卷 197-204页

作者： Chengshu Li Fan Yang institute for Advanced study Tsinghua UniversityBeijing 100084China

Lee–Yang (LY) zeros play a fundamental role in the formulation of statistical physics in terms of (grand) partition functions, and assume theoretical significance for the phenomenon of phase transitions. In this paper, motivated by recent progress in cold Rydberg atom experiments, we explore the LY zeros in classical Rydberg blockade models. We find that the distribution of zeros of partition functions for these models in one dimension (1d) can be obtained analytically. We prove that all the LY zeros are real and negative for such models with arbitrary blockade radii. Therefore, no phase transitions happen in 1d classical Rydberg chains. We investigate how the zeros redistribute as one interpolates between different blockade radii. We also discuss possible experimental measurements of these zeros.

关键词： Lee-Yang zeros Rydberg atom statistical mechanics

Transforming Education with Photogrammetry:Creating Realistic 3D Objects for Augmented Reality Applications

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Computer Modeling in Engineering & Sciences 2025年第1期142卷 185-208页

作者： Kaviyaraj Ravichandran Uma Mohan Department of Computational Intelligence School of ComputingSRM Institute of Science and TechnologyKattankulathur603203India

Augmented reality(AR)is an emerging dynamic technology that effectively supports education across different *** increased use of mobile devices has an even greater *** the demand for AR applications in education continues to increase,educators actively seek innovative and immersive methods to engage students in ***,exploring these possibilities also entails identifying and overcoming existing barriers to optimal educational ***,this surge in demand has prompted the identification of specific barriers,one of which is three-dimensional(3D)*** 3D objects for augmented reality education applications can be challenging and time-consuming for the *** address this,we have developed a pipeline that creates realistic 3D objects from the two-dimensional(2D)*** for augmented and virtual reality can then utilize these created 3D *** evaluated the proposed pipeline based on the usability of the 3D object and performance ***,with 117 respondents,the co-creation team was surveyed with openended questions to evaluate the precision of the 3D object created by the proposed photogrammetry *** analyzed the survey data using descriptive-analytical methods and found that the proposed pipeline produces 3D models that are positively accurate when compared to real-world objects,with an average mean score above *** study adds new knowledge in creating 3D objects for augmented reality applications by using the photogrammetry technique;finally,it discusses potential problems and future research directions for 3D objects in the education sector.

关键词： Augmented reality education immersive learning 3D object creation photogrammetry and StructureFromMotion

A fake projective plane constructed from an elliptic surface with multiplicities (2,4)

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Science China Mathematics 2011年第8期54卷 1665-1678页

作者： KEUM JongHae School of Mathematics Korea Institute for Advanced Study

Given any (2,4)-elliptic surface with nine smooth rational curves,eight (2)-curves and one (3)-curve,forming a Dynkin diagram of type [2,2][2,2][2,2][2,2,3],we show that a fake projective plane can be constructed from it by taking a degree 3 cover and then a degree 7 *** also determine the types of singular fibres of such a (2,4)-elliptic surface.

关键词： fake projective plane properly elliptic surface cyclic covering

LIMITATION OF AVERAGE ESHELBY TENSOR AND ITS APPLICATION IN ANALYSIS OF ELLIPSE APPROXIMATION

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Acta Mechanica Solida Sinica 2011年第2期24卷 176-184页

作者： Wennan Zou institute for Advanced study/institute of Engineering Mechanics Nanchang University Nanchang 330031 China

By the aid of irreducible decomposition, the average Eshelby tensor can be expressed by two complex coefficients in 2D Eshelby problem. This paper proved the limitation of complex coefficients based on the span of elastic strain energy density. More discussions yielded the constraints on the sampling of module and phase difference of complex coefficients. Using this information, we obtained that the maximum relative error is 65.78% after an ellipse approximation. These results, as a supplement to our previous paper, further implied that Eshelby＇s solution for an ellipsoidal inclusion could not be applied to non-ellipsoidal inclusions without taking care.

关键词： arbitrary inclusions Eshelby tensor ellipse approximation elastic strain energy density

Application of signal processing techniques to the detection of tip vortex cavitation noise in marine propeller

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Journal of Hydrodynamics 2013年第3期25卷 440-449页

作者： LEE Jeung-Hoon HAN Jae-Moon PARK Hyung-Gil SEO Jong-Soo Samsung Ship Model basin (SSMB) Marine Research Institute Samsung Heavy Industries Science TownDaejeon 305-380 Korea

The tip vortex cavitation and its relevant noise has been the subject of extensive researches up to now. In most cases of experimental approaches, the accurate and objective decision of cavitation inception is primary, which is the main topic of this paper. Although the conventional power spectrum is normally adopted as a signal processing tool for the analysis of cavitation noise, a faithful exploration cannot be made especially for the cavitation inception. Alternatively, the periodic occurrence of bursting noise induced from tip vortex cavitation gives a diagnostic proof that the repeating frequency of the bursting contents can be exploited as an indication of the inception. This study, hence, employed the Short-Time Fourier Transform （STFT） analysis and the Detection of Envelope Modulation On Noise （DEMON） specmma analysis, both which are appropriate for finding such a repeating frequency. Through the acoustical measurement in a water tunnel, the two signal processing techniques show a satisfactory result in detecting the inception of tip vortex cavitation.

关键词： tip vortex cavitation inception Short-Time Fourier Transform (STFT) Detection of Envelope Modulation On Noise(DEMON)

Effects of livestock exclusion and climate change on aboveground biomass accumulation in alpine pastures across the Northern Tibetan Plateau

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Chinese Science Bulletin 2014年第32期59卷 4332-4340页

作者： Jianshuang Wu Xianzhou Zhang Zhenxi Shen Peili Shi Chengqun Yu Baoxiong Chen Lhasa Plateau ecosystem Research Station Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences University of Chinese Academy of Sciences

To better understand the ecological and economic benefits of short-term grazing exclusion on the aboveground net primary productivity(ANPP)of alpine pastures,we conducted annual multi-site transect surveys in the summers from 2009 to 2011 and calculated the aboveground biomass discrepancy(ABD)between grazed and ungrazed pastures at plant community and economic group levels for three zonal alpine grassland types—meadow,steppe,and desert-steppe—across the northern Tibetan *** results indicated that aboveground biomass(AGB)significantly differed among grassland types and declined northwesterly from 64.07 to11.44 g m-2with decreasing precipitation and increasing *** mean ABD exhibited considerable community dependency,with meadow(12.47 g m-2)[steppe(6.91 g m-2)[desert steppe(2.54 g m-2),and it declined from 25.42 to 1.29 g m-2with decreasing precipitation and increasing temperature.‘Good forage’,*** and sedges,benefited most from grazing exclusion,followed by edible *** longer grazing exclusion durations(GEDs),the aboveground biomass of poisonous locoweeds initially decreased and then increased compared with the adjacent grazed *** the nested analysis of co-variances with a general linear model,growing season precipitation(GSP;from May to September)accounted for 52.67%ofthe observed variation in AGB,followed by AGT(9.77%)and pasture management systems(PMSs;grazing or grazing-excluded,5.31%).The variation in ABD was explained primarily by AGT(16.52%),GED(20.25%),and the interaction of AGT 9 GED(19.58%).Our results confirm that precipitation is the primary factor controlling the ANPP of alpine grasslands on the Northern Tibetan Plateau and that the ecological benefits arising from grazing exclusion are also partly dependent on grassland type and exclusion ***,spatial and temporal variations in growing season precipitation and plant functional traits or economic group composition should be jointly considered when devel

关键词：地上生物量藏北高原生物量积累牧场高山气候变化荒漠草原牲畜

study on vegetation ecological water requirement in Ejina Oasis

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Science China Earth Sciences 2007年第1期50卷 121-129页

作者： ZHAO WenZhi CHANG XueLi HE ZhiBin ZHANG ZhiHui Laboratory of Watershed Hydrology and Ecology Cold and Arid Regions Environmental and Engineering Research InstituteChi-nese Academy of SciencesLanzhou 730000China Linze Inland River basin Comprehensive Research Station Chinese Ecosystem Research NetworkLanzhou 730000China Geography and Resource Management College Ludong UniversityYantai 264025China

The Ecological Water Requirement (EWR) of desert oasis is the amount of water required to maintain a normal growth of vegetation in the special ecosystems. In this study EWR of the Ejina desert oasis is estimated through the relational equation between normalized difference vegetation index (NDVI), productivity and transpiration coefficient, which was established by a combination of the RS, GIS, GPS techniques with the field measurements of productivity. The results show that about 1.53×108 m3 water would be needed to maintain the present state of the Ejina Oasis, and the ecological water requirement would amount to 3.49×108 m3 if the existing vegetation was restored to the highest productivity level at present. Considering the domestic water requirement, river delivery loss, oasis vegetation water con-sumption, farmland water demand, precipitation recharge, etc., the draw-off discharge of the Heihe River (at Longxin Mount) should be 1.93×108―2.23 ×108 m3 to maintain the present state of the Ejina Oasis, and 4.28×108―5.17×108 m3 to make the existing vegetation be restored to the highest productiv-ity level at present.

关键词： Ejina Oasis NDVI productivity pattern vegetation ecological water requirement.

Distribution of Cu and Pb in particle size fractions of urban soils from different city zones of Nanjing, China

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Journal of Environmental Sciences 2006年第3期18卷 482-487页

作者： WANG Huan-hua LI Lian-qing WU Xin-min PAN Gen-xing institute of Resources Ecosystem and Environment of Agriculture Nanjing Agricultural University Nanjing 210095 China Chizhou Junior Teachers College Chizhou 247100 China

Soil samples from 4 defined city zones of Nanjing were randomly collected at 0-5 cm and 5-20 cm intervals and size fractions of soil particles were separated from undisturbed bulk soils by low energy dispersion procedure. The total contents of Cu and Pb in the different particle size fractions of the urban soils were analyzed by HNO3-HF-HClO4 digestion and flame atomic absorption spectrophotometer determination. The total content of Cu and Pb in soil particle size fractions varied with their size and with city zones as well. Both the content and variation with the size fractions of Pb was bigger than of Cu supporting our previous finding that there was Pb pollution to different degrees in the urban soils although the two elements were generally enriched in clay-sized fraction. Contaminated Pb tended to be preferentially enriched in the size fraction of 2000-250 μm and clay-sized fraction. While the size fractions of the soils from newly developed and preserved area contained smaller amount of Cu and Pb, the partitioning of them in coarse and fine particle size fractions were insignificant compared to that from inner residence and commercial area. The very high Pb level over 150 mg/kg of the fine particle fractions from the soils of the inner city could be a cause of high blood Pb level reported of children from the city as acute exposure to Pb of fine particles of the urban soil might occur by soil ingestion and inhalation by young children. Thus, much attention should be paid to the partitioning of toxic metals in fine soil particles of the urban soils and countermeasures against high health risk of Pb exposure by soil ingestion and dust inhalation should be practiced against the health problem of blood Pb for young children from the cities.

关键词： urban soil city zone soil contamination particle size fraction heavy metals lead health risk