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1.
This paper discusses the spatial knowledge related to a line,and the characteristic points of lines is detected.According to the requirements of line generalization,new algorithms for identifying characteristic line points are presented.These characteristic points are used to improve the algorithms of line generalization.An algorithm for identifying bends is shown.In this paper,improved algorithms based on those by Douglas-Peucker,Visvalingam and Whyatt are shown.In this test,the progressive process of line generalization is emphasized. 相似文献
2.
Impacts of tectonic and orbital forcing on East African climate: a comparison based on global climate model simulations 总被引:1,自引:1,他引:0
Frank Kaspar Kerstin Prömmel Ulrich Cubasch 《International Journal of Earth Sciences》2010,99(7):1677-1686
A global atmosphere–ocean model has been forced with topographic and orbital scenarios in order to evaluate the relative role
of both factors for the past climate of East Africa. Forcing the model with a significantly reduced topography in Eastern
and Southern Africa leads to a distinct increase in moisture transport from the Indian Ocean into the eastern part of the
continent and increased precipitation in Eastern Africa. Simulations with step-wise reduced height show that this climate
change occurs continuously with the change in topography, i.e., an abrupt change of local climatic features with a critical
height is not found. Simulations of the last interglacial (at 125,000 years before present, i.e., the Eemian interglacial)
and the last glacial inception (at 115,000 years before present) are used as examples for the role of orbital-induced changes
in insolation. Here, changes in meridional temperature gradients lead to modifications in moisture transport of similar order
of magnitude, but with different spatial and seasonal structure. For the Eemian interglacial, a distinct increase in summer
moisture transport from the Atlantic deep into the continent at around 20°N is simulated. 相似文献
3.
This paper presents an algorithm to decompose the modulated RHESSI light curves into periodic functions and a smooth function,
representing the true (demodulated) time profile of an impulsive source. The decomposition is achieved by optimizing a trade-off
between the Poisson likelihood, a smoothness constraint, and conditions on the average grid transmission and the (modulating
or non-modulating) background. The algorithm, which operates on the level of count rates and does not require imaging information,
is verified by numerical simulations and applied to some early RHESSI data, where – as a preliminary result – several impulsive
features on time scales < 4 s may have been identified. 相似文献
4.
Reiser Martin Kaspar Schuster Ralf Spikings Richard Tropper Peter Fügenschuh Bernhard 《International Journal of Earth Sciences》2017,106(2):659-685
International Journal of Earth Sciences - New Ar–Ar muscovite and Rb–Sr biotite age data in combination with structural analyses from the Apuseni Mountains provide new constraints on... 相似文献
5.
Ionuţ Iosifescu Enescu Vassilios Vescoukis Cristina M. Iosifescu Enescu Fabian Müller Nadia H. Panchaud Lorenz Hurni 《The Cartographic journal》2013,50(2):137-148
The geospatial field significantly influences the development of the environmental domain, including a wide range of geospatial and cartographic information systems, such as Geographic Information Systems (GIS), Multimedia Atlas Information Systems (MAIS) and more recently web-based GIS (Web-GIS). In this context, we introduce web-based environmental geospatial information systems (Web-EGIS) as a special case of Web-GIS, aiming to integrate the functionalities of geospatial information systems with the enormous quantity of specialized, distributed and highly heterogeneous environmental geo-referenced data and services. We define three main characteristics of the Web-EGIS. The first is a generic hypercube-based data organization and visualization. The next characteristic is a standard-based, three-tier service-oriented architecture. The third and last characteristic is the traceability of the architectural and design decisions, for which we introduce the new concept of an ‘Environmental Application Context’, arguing that not only the functional but also the non-functional requirements (NFRs) have an important role in defining the architecture, software components and data services of such systems. In a nutshell, a Web-EGIS is characterized by a coherent user experience through the hypercube-based visualization concept, technically supported by a service-oriented architecture that is structured according to an extensive analysis of NFRs. On this basis, we introduce the Geodata visualization and interactive training environment (GeoVITe) Platform for Interdisciplinary Environmental Research as a reference implementation of a Web-EGIS with its basic design requirements, integrative hypercube-based visualization for heterogeneous data sources, extended web cartography functionalities, and its de facto system architecture. The concept of the hypercube-based visualization is better transferred to the system architecture by understanding the ‘Environmental Application Context’ of this particular Web-EGIS, which also makes it easier to maintain and enhance. The resulting system is a support platform for research activities in the environmental domain. 相似文献
6.
An application of line simplification considering spatial knowledge is described. A method for identifying potential conflict regions, in order to avoid the self-intersection of generalized, lines, is also discussed. Further-more, a new progressive line simplification algorithm is presented. From the view point of spatial cognition, a spatial hierarchical structure is proposed, and its application to construction of spatial knowledge related to a line is explained. 相似文献
7.
Heinrich F. Kaspar Rodney A. Asher Ian C. Boyer 《Estuarine, Coastal and Shelf Science》1985,21(2):245-255
In January 1982, sediment microbial N transformations and inorganic N fluxes across the sediment/water interface were studied at nine sites off the South Island West Coast, New Zealand. The sediments showed a great variety in physical, chemical and biological properties. The sediment organic matter had a molar ratio of 5.9–10.9, and the total ratio was 1.2–4.0. The denitrification capacity in the top 7.5 cm of sediment was 0.1–77.2 mmol N m?2 day?1 and generally declined with increasing sediment depth. The in situ denitrification rate was 0.02–1.84 mmol N m?2 day?1 and highest activities were generally found in surface sediments and at 6–7.5 cm depth. Denitrification accounted for 82–100% of total nitrate reduction. Net N mineralization was indirectly estimated at 0.6–2.4 mmol N m?2 day?1, and the experimental determination of this N transformation gave 0.6–3.2 mmol N m?2 day?1. Denitrification accounted for 3–75% of net N mineralization. The diffusive flux of ammonium and nitrate across the sediment/water interface was 0.1–0.7 and 0.1–0.6 mmol N m?2 day?1, respectively. 相似文献
8.
J. Kaspar I. Hudec P. Schiller G. B. Cook A. Kitzinger E. W lfl 《Chemical Geology》1972,10(4):299-305
The content of gold in plants has been used as an indicator in the prospecting for gold. For this purpose non-destructive analytical methods have been developed. In the humid mild zone — where the process of weathering is of a kaolinitic character — there is practically no migration of gold, and consequently its increased content indicates the presence of a gold deposit. 相似文献
9.
Tracing glacier wastage in the Northern Tien Shan (Kyrgyzstan/Central Asia) over the last 40 years 总被引:2,自引:1,他引:1
Peter Niederer Viktor Bilenko Natasha Ershova Hans Hurni Sergeji Yerokhin Daniel Maselli 《Climatic change》2008,86(1-2):227-234
The status and dynamics of glaciers are crucial for agriculture in semiarid parts of Central Asia, since river flow is characterized
by major runoff in spring and summer, supplied by glacier- and snowmelt. Ideally, this coincides with the critical period
of water demand for irrigation. The present study shows a clear trend in glacier retreat between 1963 and 2000 in the Sokoluk
watershed, a catchment of the Northern Tien Shan mountain range in Kyrgyzstan. The overall area loss of 28% observed for the
period 1963–2000, and a clear acceleration of wastage since the 1980s, correlate with the results of previous studies in other
regions of the Tien Shan as well as the Alps. In particular, glaciers smaller than 0.5 km2 have exhibited this phenomenon most starkly. While they registered a medium decrease of only 9.1% for 1963–1986, they lost
41.5% of their surface area between 1986 and 2000. Furthermore, a general increase in the minimum glacier elevation of 78 m
has been observed over the last three decades. This corresponds to about one-third of the entire retreat of the minimum glacier
elevation in the Northern Tien Shan since the Little Ice Age maximum. 相似文献
10.
1 IntroductionMapgeneralizationisoneoftheclassicalcartographicprob lems.Allmaps,aregeneralizedrepresentationsofthereality.Generalizationisnecessarytoimprovethedisplayqualityofsmallscalemaps,allowanalysiswithdifferentgradesofdetail;andreducedatastoragere… 相似文献