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排序方式: 共有157条查询结果,搜索用时 15 毫秒
71.
Images of the sub-polar regions of Mars show existence of various seasonal-depending features, including mosaics of dark patches called Dalmatian spots. We interpret formation of dark patches on dune fields by means of the non-uniform sublimation of winter CO2 ice deposit. 相似文献
72.
73.
Assessment of GPS + Galileo and multi-frequency Galileo single-epoch precise positioning with network corrections 总被引:1,自引:0,他引:1
Several processing strategies that use dual-frequency GPS-only solution, multi-frequency Galileo-only solution, and finally tightly combined dual-frequency GPS + Galileo solution were tested and analyzed for their applicability to single-epoch long-range precise positioning. In particular, a multi-system GPS + Galileo solution was compared to GPS double-frequency solution as well as to Galileo double-, triple-, and quadruple-frequency solutions. Also, the performance of the strategies was analyzed under clear-sky and obstructed satellite visibility in both single-baseline and multi-baseline modes. The results indicate that tightly combined GPS + Galileo instantaneous positioning has a clear advantage over single-system solutions and provides an accurate and reliable solution. It was also confirmed that application of multi-frequency observations in case of Galileo system has an advantage over a dual-frequency solution. 相似文献
74.
Grzegorz Lizurek Beata Plesiewicz Pawe? Wiejacz Jan Wiszniowski Jacek Trojanowski 《Acta Geophysica》2013,61(1):26-36
The earthquake of magnitude M L = 3:8 (EMSC) took place on Friday, 6 January 2012, north-east of the town of Jarocin in Wielkopolska Region, Poland. The only historical information about past earthquakes in the region was found in the diary from 1824; apart of it, there was a seismic event noticed in the vicinity of Wielkopolska in 1606 (Pagaczewski 1982). The scope of this paper is to describe the 6 January 2012 event in view of instrumental seismology, macroseismic data analysis and known tectonics of the region, which should be useful in future seismic hazard analysis of Poland. 相似文献
75.
Magdalena Kądziałko-Hofmokl Jacek Szczepański Tomasz Werner Maria Jeleńska Krzysztof Nejbert 《Acta Geophysica》2013,61(3):535-568
The results of palaeomagnetic, rock magnetic, and microscopic study of Early Paleozoic metabasites and granulites from the Orlica?nie?nik Dome (OSD, Sudetes) have been combined with geochronological data. In the eastern part of the OSD (?nie?nik Massif, SM) ferrimagnetic pyrrhotite is prevalent, accompanied by various amounts of Fe-oxides. In the western part of the OSD (Orlica-Bystrzyca Massif, OBM) Fe-oxides dominate. All magnetic minerals originated during hydrothermal and weathering processes. The palaeomagnetic study revealed the presence of three secondary components of natural remanence: Late Carboniferous, Late Permian, and Mesozoic. Two Paleozoic components are related to volcanic activity in the Sudetes. They are carried by pyrrhotite and Fe-oxides and were isolated only in SM rocks. The Mesozoic component was determined in both parts of the OSD and is carried by Fe-oxides. It covers a time span, from ~160 to ~40 Ma, corresponding to a long period of alteration. 相似文献
76.
Jacek Andrzej Urbanski 《International journal of geographical information science》2013,27(7):723-730
This paper advocates the use of GIS for the evaluation of the vulnerability of coastal waters and presents a method for mapping their vulnerability to algal blooms. The method incorporates probability mapping of parameters used to describe coastal waters and fuzzy sets. To allow the modelling of processes where some components cannot substitute for other components the 'no trade off' convex combination formula is proposed. The maps of vulnerability for the Gulf of Gdansk, which were created using this method, may be used to find out which rivers and water discharges play a dominant role in eutrophication. 相似文献
77.
Jacek Malczewski Piotr Jankowski 《International journal of geographical information science》2020,34(7):1257-1282
ABSTRACT A majority of research on Spatial Multicriteria Analysis (SMCA) has been spatially implicit. Typically, SMCA uses conventional (aspatial) multicriteria methods for analysing and solving spatial problems. This paper examines emerging trends and research frontiers related to the paradigm shift from spatially implicit to spatially explicit multicriteria analysis. The emerging trend in SMCA has been spatially explicit conceptualizations of multicriteria problems focused on multicriteria analysis with geographically varying outcomes and local multicriteria analysis. The research frontiers align with conceptual and structural elements of SMCA and pertain to, among others, theoretical frameworks, problem structuring, model parameter derivation, decision problem contextualization, scale representation, treatment of uncertainties, and the very meaning of decision support. The paper also identifies research directions and challenges associated with developing spatially explicit multicriteria methods and integrating concepts and approaches from two distinct fields: GIS and multicriteria analysis. 相似文献
78.
Jacek Grabowski János Haas Emö Márton Andrzej Pszczółkowski 《Studia Geophysica et Geodaetica》2010,54(1):1-26
Jurassic-Cretaceous sediments of Transdanubian Range in Northern Hungary mostly retain their primary magnetizations and are
suitable for detailed bio- and magnetostratigraphic studies. The Lókút section, 13 m in thickness, is localized in the central
part of the Transdanubian Range. It contains the Jurassic/Cretaceous boundary in pelagic carbonate facies. Although the colour
of the rocks changes from reddish-pinkish in the bottom to almost white at the top of the section, magnetite was identified
as a magnetic carrier without evidence of hematite. Integrated bio- and magnetostratigraphical investigations resulted in
construction of chronostratigraphical scheme. The section, embraces magnetozones from M21r to M18r, of upper Lower Tithonian
(Parastomiosphaera malmica Zone) to Lower Berriasian age (Calpionella alpina Subzone). Sedimentation rate of pelagic limestones
increased from 1–3 m/My during Tithonian to 5–7 m/My during Berriasian. The sedimentation rate and its changes up the section
are comparable to those from the Jurassic/Cretaceous boundary sections of Trento plateau (Southern Alps, Italy) — sedimentary
environments of Trento plateau and central Transdanubian Range in that time might be similar. Sedimentation rate within Umbrian
Apennine basins and Križna unit in the Western Tatra Mts. seems significantly higher. Analysis of rock magnetic parameters
reveals that detrital input was much lower into the Lókút section than into Križna basin in the Tatra Mts. (Zliechov trough).
Increase of sedimentation rate occurs in both sections in the Upper Tithonian — Lower Berriasian. It coincides with the onset
of calpionellid limestone facies and is related to increased productivity of calcareous micro- and nannoplankton. Detailed
correlation of both sections basing on rock magnetic parameters and susceptibility changes is, however, not possible. They
are dependent mostly on the local sedimentary conditions (Bakony Mts. — deep water plateau; Križna unit — deep water trough)
and correlation with any “global” paleoenvironmental (climatic, eustatic) trends is not straightforward. 相似文献
79.
High Potential Regions for Enhanced Geothermal Systems in Canada 总被引:1,自引:0,他引:1
Previous estimates of geothermal energy potential in Canada give an indication of available heat to be ‘farmed’ at depth.
This article examines in more detail depth–temperature relationships near large population centers in western Canada, as well
as remote communities in northern Canada, in order to provide a first order assessment of Enhanced Geothermal Systems (EGS)
potential for electrical generation. Quantities of EGS thermal power output and electrical generation are dependent on output
temperature and flow rate. We relate these potential power rates as a whole to drilling and installation cost for the doublet
systems and triplet system. Results show areas with significant EGS potential in northern Alberta, northeastern British Columbia,
and southern Northwest Territories related to high heat flow and thermal blanketing of thick sedimentary cover. Estimated
installation costs in 2008 dollars are under 2 mln$/MWe. We also estimate significant reductions in CO2 emissions by conversion to geothermal electric production. 相似文献
80.
Results of the application of tropospheric corrections from different troposphere models for precise GPS rapid static positioning 总被引:1,自引:0,他引:1
Paweł Wielgosz Jacek Paziewski Andrzej Krankowski Krzysztof Kroszczyński Mariusz Figurski 《Acta Geophysica》2012,60(4):1236-1257
In many surveying applications, determination of accurate heights is of significant interest. The delay caused by the neutral
atmosphere is one of the main factors limiting the accuracy of GPS positioning and affecting mainly the height coordinate
component rather than horizontal ones. Estimation of the zenith total delay is a commonly used technique for accounting for
the tropospheric delay in static positioning. However, in the rapid static positioning mode the estimation of the zenith total
delay may fail, since for its reliable estimation longer observing sessions are required. In this paper, several troposphere
modeling techniques were applied and tested with three processing scenarios: a single baseline solution with various height
differences and a multi-baseline solution. In specific, we introduced external zenith total delays obtained from Modified
Hopfield troposphere model with standard atmosphere parameters, UNB3m model, COAMPS numerical weather prediction model and
zenith total delays interpolated from a reference network solution. The best results were obtained when tropospheric delays
derived from the reference network were applied. 相似文献