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Examining El Nio in the Holocene: implications and challenges

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National Science Review 2018年第6期5卷 807-809页

作者： Zhengyao Lu Zhengyu Liu department of Physical geography and Ecosystem Science Lund University department of geography Ohio State University

The El Nio–Southern Oscillation(ENSO) is characterized by year-to-year anomalous surface climate variability over the tropical Pacific. Through atmospheric teleconnections, ENSO can bring droughts and floods worldw... 详细信息

关键词： Examining El Ni implications and challenges o in the Holocene El

SOME RESULTS ON A DEGENERATE AND SINGULAR DIFFUSION EQUATION

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Acta Mathematica Scientia 2007年第3期27卷 581-601页

作者：姚正安周文书 department of Mathematics Zhongshan University

In this article, a degenerate and singular diffusion problem is studied. The existence of solutions is established by parabolic regularization. Some properties of solutions, for instance, asymptotic behavior, are also... 详细信息

关键词： Degenerate and singular diffusion equation weak solution existence asymptotic behavior

Fractional integration associated with second order divergence operators on R^n

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Science China Mathematics 2003年第3期46卷 355-363页

作者：邓东皋颜立新 department of Mathematics Zhongshan University

The classical Hardy-Littlewood-Sobolev theorems for Riesz potentials (?Δ)?α/2 are extended to the generalised fractional integrals L –α/2 for 0 < α < n, where L=?div A? is a uniformly complex elliptic operator wi... 详细信息

关键词： fractional integral second order divergence operator semigroup Hardy- Littlewood- Sobolev theorem

Spatial Pattern Evolution and Casual Analysis of County Level Economy in Changsha-Zhuzhou-Xiangtan Urban Agglomeration, China

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Chinese Geographical Science 2014年第5期24卷 620-630页

作者： DONG Minghui ZOU Bin PU Qiang WAN Neng YANG Lingbin LUO Yanqing department of geography Hunan University of Arts and Science department of Geomatics and Remote Sensing Central South University department of geography University of Utah department of geography Northeast Normal University

In order to evaluate whether or not the county units′ economy in the Changsha-Zhuzhou-Xiangtan(Chang-Zhu-Tan) Urban Agglomeration was growing as expected, this study analyzed the spatial economy pattern at county-level by using the Exploratory Spatial Data Analysis(ESDA) method. In this process, the global Moran′s I and local Getis-Ord G*i indexes were employed to analyze indicators including per capita GDP and three industrials(i.e. primary, secondary and tertiary industry) from 2000 to 2010. The results show that: 1) the county units′ economy in the Chang-Zhu-Tan Urban Agglomeration has exhibited a strong spatial autocorrelation and an accelerated integration trend since 2008(Moran′ s I increased from 0.26 to 0.56); 2) there is a significant difference in economy development between the northern and southern county units in the Chang-Zhu-Tan Urban Agglomeration: the hotspot zone with high economic level was formed among the northern county units whereas the coldspot zone with low economic level was located in the southern areas. This difference was caused primarily by the increasingly prominent economic radiation effect of Changsha ′upheaval′; 3) town density, secondary industry, and the integration policy are the major contributors driving the evolution of the spatial economy pattern in the Chang-Zhu-Tan Urban Agglomeration.

关键词： spatial autocorrelation spatial heterogeneity urban agglomeration county-level economy Changsha-Zhuzhou-Xiangtan (Chang-Zhu-Tan), China

The initial elevation of palaeokarst and planation surfaces on Tibet Plateau

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Chinese Science Bulletin 1997年第11期42卷 934-939页

作者： Cui, ZJ Gao, QZ Liu, GN Pan, BT Chen, HL department of geography Peking University Beijing China department of geography Lanzhou University Lanzhou China

THE formation periods,properties and initial elevations of Tibetan planation surfaces are keysto the issues ot the plateau *** et *** that the study on planation surfaces hasfar-reaching *** et *** that the summit lev... 详细信息

关键词： Tibet Plateau planation surface period elevation.

Comparing the terrain reversal effect in satellite images and in shaded relief maps:an examination of the effects of color and texture on 3D shape perception from shading

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International Journal of Digital Earth 2019年第4期12卷 442-459页

作者： Arzu Çöltekin Julien Biland department of geography University of ZurichZurichSwitzerland department of geography University of BernBernSwitzerland

Terrain reversal effect(TRE)causes reversed 3D shape perception in satellite images and shaded relief maps(SRMs),and introduces difficulties in identifying landforms such as valleys and *** this paper,in a controlled laboratory experiment,we compare how well 27 participants could identify valleys and ridges over 33 locations using SRMs,color satellite images and grayscale satellite *** main depth cue is shadow both in vertical-view images and ***,the presence of texture and color in images also affect 3D shape *** our participants experience the illusion strongly:with the SRMs,it is very severe(2%accuracy),with grayscale images low but considerably better than SRMs(17.6%accuracy),and slightly worse with color imagery(15.3%accuracy).These differences between SRMs and imagery suggest that the participants who are able to bypass the illusion consciously or subconsciously interpret the photographic *** support this observation further with a cue-strength ***,we provide exploratory analyses of the effects of expertise,global convexity bias,and bistable *** original empirical observations serve towards a better understanding of this visual illusion,and contribute towards nuanced and appropriate solutions to correcting for TRE differently for satellite images and SRMs.

关键词： Terrain reversal relief inversion false topographic perception phenomenon photo interpretation visual illusion user study bistable perception global convexity bias

HUNGARIAN SEMIGROUPS, THE ARITHMETIC OF GENERALIZED RENEWAL SEQUENCES AND SEMI-P-FUNCTIONS

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Chinese Annals of Mathematics,Series B 1990年第2期11卷 127-137页

作者：梁之舜黄之瑞 department of Mathematics Zhongshan UniversityGuangzhou department of Mathematics Zhongshan University Guangzhou

In this paper the authors discuss the additional conditions under which a Hungarian semigroup is possessed of the fundamental Delphic properties. It is proved that both the positive generalized renewal sequence semigroup and the tame semi-p-function semigroup are Hungarian semigroups and possessed of the fundamental Delphic properties. Then the arithmetic properties of these two classes of the special semigroups are studied respectively.

关键词： semigroup renewal arithmetic erior possessed hereditary algebra Kendall 落兀 uniformly

Modeling of taxi drivers’ experience for routing applications

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Science China(Technological Sciences) 2010年第S1期53卷 44-51页

作者： SHAW ShihLung department of geography University of Tennessee

Taxi drivers drive on the roads every day and become very knowledgeable of the spatiotemporal traffic patterns in a *** therefore is reasonable to assume that the routes chosen by taxi drivers often work out better than those selected by other *** dynamic navigation assistance based on real-time traffic information faces limitations such as the spatial coverage of real-time data collection sites,performance of real-time data processing and communications,and accuracy of short-term traffic forecasts in a large urban area,experiences gained by taxi drivers can be a valuable data source for improving the quality of vehicle navigation *** paper develops a vehicle navigation guidance system based on taxis drivers’ knowledge derived from floating car data collected over an extended time *** then classify road segments based on the spatiotemporal characteristics of taxi tracking data.A case study using taxi tracking data collected in Wuhan,China is presented in this paper to demonstrate the performance of this vehicle navigation system based on taxi tracking data.

关键词： floating car data vehicle navigation system route guidance geographic information systems

Methane Dynamics in Northern Peatlands: A Review

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Pedosphere 2009年第4期19卷 409-421页

作者： D. Y. F. LAI department of geography McGill University

Northern peatlands store a large amount of carbon and play a significant role in the global carbon cycle. Owing to the presence of waterlogged and anaerobic conditions, peatlands are typically a source of methane (CH4), a very potent greenhouse gas. This paper reviews the key mechanisms of peatland CH4 production, consumption and transport and the major environmental and biotic controls on peatland CH4 emissions. The advantages and disadvantages of micrometeorological and chamber methods in measuring CH4 fluxes from northern peatlands are also discussed. The magnitude of CH4 flux varies considerably among peatland types (bogs and fens) and microtopographic locations (hummocks and hollows). Some anthropogenic activities including forestry, peat harvesting and industrial emission of sulphur dioxide can cause a reduction in CH4 release from northern peatlands. Further research should be conducted to investigate the in fluence of plant growth forms on CH4 flux from northern peatlands, determine the water table threshold at which plant production in peatlands enhances CH4 release, and quantify peatland CH4 exchange at plant community level with a higher temporal resolution using automatic chambers.

关键词： global carbon cycle greenhouse gas methane oxidation methanogenesis methanotrophy