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Pilleriine Kamenjuk Anto Aasa Jaanus Sellin 《International journal of geographical information science》2017,31(7):1425-1447
Similar to every process involving quantitative research, the study of migration heavily depends on the data available for analysis. The available movement data limit the type of questions that can be asked, and as a result, certain aspects of human spatial mobility have yet to be examined. The development of information and communication technologies and their widespread adoption offers new datasets, methods and interpretations that make it possible to study social processes at a new level. For example, mobile positioning data can aid in overcoming certain constraints embedded in traditional data sources (such as censuses or questionnaires) for study of the connections between daily mobility and change of residence. This study presents a framework for mapping changes of residence using data from passive mobile positioning and an anchor point model to better understand the limits of these methods and their contribution to understanding long-term mobility. The study concludes that the most important considerations in monitoring change of residence using passive mobile position data include the continuity of the time-series data, the varying structure of the mobile tower network and the diversified nature of human mobility. The fine spatial and temporal granularities of passive mobile positioning data allow us to study human movement at a detailed scale. 相似文献
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Lake Peipsi has a surface area of 3,555 km2 and is the fourth largest inland body of water in Europe and one of the best-stocked for fish. Its complex geological history was controlled by the retreat of the Late Pleistocene ice, and more recently by climatic fluctuations and neotectonic movements. The northern part of the N-S elongated basin is now rising, the central part is stable, and the southern part is sinking, but in the past, the differences in elevations were much greater. These processes are still causing the water to spread from north to south, where flooding of large areas poses many social problems. Because of the considerable water-level fluctuations, exceeding 3 m, both the surface area and the volume of the lake vary greatly. High water levels cause marked shoreline damage and pose a serious threat to the buildings and roads in the immediate vicinity. Extensive changes on the coast are also due to the action of hummocky lake ice. 相似文献
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Comparison of some structure contour of northeastern and southeastern Estonia with the bedrock relief patterns leads to the conclusion that direct morphostructures are infrequent in those areas. The formation of bedrock and contemporary relief has been little effected by differential postglacial and recent crustal movements. Morphotectonic analysis enables us to determine the character of those movements only in a few cases. 相似文献
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Abstract— The Ilumetsa impact craters were discovered in 1938 in the course of geological mapping. In the crater field area, the Middle Devonian bedrock consists of light‐yellow weakly cemented siltstones and sandstones of the Givetian Burtnieki Regional Stage, which are overlain by a 1–2 m thick layer of reddish‐brown loamy till. Põrguhaud, the biggest crater, has a diameter of 75–80 m at the top of the uplifted rim and is 12.5 m deep. The zone of authochtonous breccias below the apparent crater extends to 30 m deep. The crater is partly filled with a thin layer of gyttja and peat up to 2 m thick. Radiocarbon ages of 6030 ± 100 (TA‐310) and 5910 ± 100 (TA‐725) years B.P. from the lowermost organic layer and palynological evidence suggest that the age of the impact was ～6000 14C years B.P. The Sügavhaud crater has a diameter of 50 m at the top of the rim and is 4.5 m deep. Organic matter on the bottom of the crater is absent. As precise age determination of the Ilumetsa craters by direct dating methods has proved inconclusive, we proposed a method of geological correlation which is based on the occurrence of impact spherules in lake and bog sediments around the crater field. Radiocarbon dating of samples from a peat layer with glassy spherules of impact origin in the Meenikunno Bog, 6 km southwest of the Ilumetsa crater field, yielded the ages of 6542 ± 50 (Tln‐2214) for the depth interval 5.6–5.7 m and 6697 ± 50 (Tln‐2316) years B.P. for the depth interval 5.7–5.8 m. These dates suggest that the Ilumetsa craters were formed ～6600 years ago. 相似文献
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Anto A. Micheal K. Vani S. Sanjeevi 《Journal of the Indian Society of Remote Sensing》2014,42(2):445-451
Lunar surface exploration is increasing rapidly with priority being given to precision of lunar soft landing. Lunar soft landing is achieved when craters and grabens are used as navigational landmarks. Grabens are formed from localized tensional stress fields or from near-surface dike emplacement. These tectonic features tend to have consistently straight or accurate parallel-striking walls bounded by steep, inward-dipping normal faults. Aiming at navigational application, a novel approach for automatic graben detection based on Hessian technique has been implemented on Digital Terrain Model (DTM) of lunar image. The Hessian technique uses gradient change as a key parameter to identify grabens. Adaptive Binarization using Otsu method is used to extract graben features from the Hessian image. Features such as small grabens and craters are removed using morphological operations, resulting in significant appearance of grabens. The experiment is conducted in different DTM images of lunar surface and the results indicate 90 % of the grabens are detected. The statistical results are evaluated based on visual interpretation, for both automatic and manual graben detection. It is observed that the proposed automatic graben detection technique gives better results than the manual detection. 相似文献
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The effects of neutrino mass and oscillations are investigated in the calculations of energy losses of solar neutrinos. In these calculations, we take into account the full energy dependence of the stopping power of matter for neutrinos. The case of Majorana neutrinos are also investigated. It is found that the total losses of energy of solar neutrinos are too small to account for the solar neutrino problem. 相似文献
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To describe and analyse the role of sediments in the matter cycling in large shallow transboundary Lake Peipsi (L. Peipsi)
in north-eastern Europe, detailed surface-sediment mapping was conducted. On the basis of grain size the surface sediments
fall into three groups: coarse-grained sediments (prevailingly sands in the lake’s southern part), fine-grained sediments
(mainly silts) and silty sands, both in the central deeper part within the 8-m depth contour. The groups of deposits have
a distinct spatial distribution, determined mainly by the current system in the lake. The main source of bottom sediments
is the erosion of the lake floor and shores, the role of the river input seems to be limited. Fine-grained organic-rich sediments
are very cohesive, playing the main role in the circulation of various inorganic and organic pollutants like nutrients and
xenobiotics. Due to the cohesive character of the sediments their physical and chemical properties are extremely diverse and
if the near-bottom shear stress increases (extreme meteorological events, changes in the water level, etc.), the lake floor
may be subjected to episodic erosion and resuspension, which may cause remobilisation of impurities in muddy sediments and
their return to the food chain. 相似文献
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