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181.
Andrea Dalla Torre Paolo Gallo Chris Marshall Angelo Montanari Federico Pittino 《地球空间信息科学学报》2019,22(2):89-106
ABSTRACTThe widespread availability of mobile communication makes mobile devices a resource for the collection of data about mobile infrastructures and user mobility. In these contexts, the problem of reconstructing the most likely trajectory of a device on the road network on the basis of the sequence of observed locations (map-matching problem) turns out to be particularly relevant. Different contributions have demonstrated that the reconstruction of the trajectory of a device with good accuracy is technically feasible even when only a sparse set of GNSS positions is available. In this paper, we face the problem of coping with sparse sequences of cellular fingerprints. Compared to GNSS positions, cellular fingerprints provide coarser spatial information, but they work even when a device is missing GNSS positions or is operating in an energy saving mode. We devise a new map-matching algorithm, that exploits the well-known Hidden Markov Model and Random Forests to successfully deal with noisy and sparse cellular observations. The performance of the proposed solution has been tested over a medium-sized Italian city urban environment by varying both the sampling of the observations and the density of the fingerprint map as well as by including some GPS positions into the sequence of fingerprint observations. 相似文献
182.
The introduction of exotic marine species has caused considerable economic and ecological damage around the world. Some of these species possess adaptations such as secondary metabolites which facilitate their successful invasion into new areas. In this study we tested two hypotheses: (i) crude extracts produced by two invasive hard corals Tubastraea coccinea and Tubastraea tagusensis, introduced to the southwest Atlantic, inhibit predation by generalist fish; (ii) substances found in the crude extracts of both species reduce or enhance the settlement of other organisms. In an in situ palatability bioassay the extract of T. tagusensis reduced predation by generalist fish. The extracts of both species of coral showed species‐specific effects on fouling organisms in in situ gel plate bioassays. Control and extract plates had similar total cover, although plates with extracts had significantly fewer Cladophora sp., and Lithophyllum sp. was only detected on control gels. In contrast, a hydrozoan was only found on plates with extracts and overall community ordination demonstrated clear differences in the fouling communities between treatments. These results demonstrate that both coral species have chemical substances which can bring about a negative interaction with potential fish predators and competitors such as algal and invertebrate foulers and the advantage gained could explain their success in invading new regions to the detriment of local fauna and flora. 相似文献
183.
F. A. Temporim Ricardo Ivan Ferreirae da Trindade Marcos Egydio-Silva Tiago Valim Angelo Eric Tohver Caroline Cibele Soares Lucas Pequeno Gouvêa Julio Cesar Mendes Silvia Regina Medeiros Antônio Carlos Pedrosa-Soares Gabriel Gomes Silva 《地学学报》2023,35(1):23-31
Featuring 3 000-km-long large and hot orogen, the Mantiqueira Province provides a rare opportunity to study the process of gravitational collapse at mid to deep crustal levels. Distinct but contemporary (~500 Ma) post-collisional intrusions show structures and anisotropy of magnetic susceptibility (AMS) fabrics related to their emplacements, recording different flow patterns. In southern deep-seated intrusions, ellipsoidal-shaped roots with gabbroic-to-hybrid cores surrounded by granitic rocks show concentric patterns of AMS fabrics that cut across the NE-trending regional foliation. In contrast, northern intrusions, exposed as the upper sections of batholith-size bodies of coarse-grained granite emplaced at the shallow to mid-crust, show general NS-trending magnetic fabrics roughly parallel to strike of the orogen and the regional foliation of host rocks. These contrasting magnetic patterns from shallow to deeper crust suggest vertical magma migration from the overthickened orogenic core to be emplaced across its thinner stretched flanks during the gravitational collapse of the orogenic edifice. 相似文献