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91.
Mahmoud Sakr Esteban Zimányi Alejandro Vaisman Mohamed Bakli 《Transactions in GIS》2023,27(2):323-346
Performance indicators of road networks are a long-lasting topic of research. Existing schemes assess network properties such as the average speed on road segments and the queuing time at intersections. The increasing availability of user trajectories, collected mainly using mobile phones with a variety of applications, creates opportunities for developing user-centered performance indicators. Performing such an analysis on big trajectory data sets remains a challenge for the existing data management systems, because they lack support for spatiotemporal trajectory data. This article presents an end-to-end solution, based on MobilityDB, a novel moving object database system that extends PostgreSQL with spatiotemporal data types and functions. A new class of indicators is proposed, focused on the users' experience. The indicators address the network design, the traffic flow, and the driving comfort of the motorists. Furthermore, these indicators are expressed as analytical MobilityDB queries over a big set of real vehicle trajectories. 相似文献
92.
Short-range forecast of heavy precipitation and strong wind using the convection-allowing WRF models
N. F. Vel’tishchev V. D. Zhupanov Yu. B. Pavlyukov 《Russian Meteorology and Hydrology》2011,36(1):1-10
The results are stated of estimation of short-range forecasting of heavy precipitation (P ≥ 10 mm/12 hours) and strong wind at the height of 10 m (V ≥ 10 m/s) using three nonhydrostatic models from the WRF family: ARW, ARW Glob, and NMM. The forecasts on the basis of all three models were carried out using two grids. The horizontal resolution of external grids varied from 9 to 16.5 km and that of the nested grids, from 3 to 5.5 km. For the ARW and NMM models, the values at side boundaries of external nested grids were taken from the forecasts on the basis of the global GFS NCEP model and for the ARW Glob model, from the global forecasts based on this model. The convection parameterization was turned off at nested grids for all models. The forecasts of heavy precipitation and strong wind at nested grids over the European territory of Russia were estimated from the radar and station measurements in summer 2008. It is obtained that all three models reproduce well enough the mesoscale convective systems and associated areas of heavy precipitation and strong wind but they have common shortcomings: they overestimate the amount and area of heavy precipitation and underestimate the strong wind speed. To a lesser degree, these shortcomings are typical of the ARW model. The possible reasons for systematic errors in the forecasts are discussed. 相似文献
93.
94.
Brazil has extensive sugar cane monocultures, which significantly alter hydrogeochemical material fluxes. We studied dissolved organic matter (OM) fluxes in the Manguaba lagoon-estuary system, which drains a sugar cane monoculture-dominated hinterland and discharges into the Atlantic coastal ocean. The OM fluxes into the lagoon originate from baseflow, field runoff and sugar cane factory effluents. In the study, dissolved organic carbon (DOC) concentration, δ13C DOC and UV absorbance were analysed along a freshwater-seawater salinity gradient that encompasses river (DOC 9-11 mg l−1, δ13C −22.2‰ to −25.5‰); lagoon (4-11 mg l−1, −20.5‰ to −24.8‰); estuary (3-9 mg l−1, −22.6‰ to −25.3‰) and coastal waters (1.64 mg l−1, −21‰) with different intra-seasonal runoff conditions. We used the carbon isotope data to quantify the sugar cane derived DOC. Where river water meets brackish lagoon water, substantial loss of DOC occurs during rainy conditions, when suspended sediment from eroded fields in the river is very high. During dry weather, at much lower suspension levels, DOC increases, however, presumably from addition of photolysed resuspended sedimentary OM. In the estuary, mixing of DOC is strictly conservative. Ca. 1/3 of riverine DOM discharged into the lagoon has a sugar cane source. Within the lagoon on avg. 20% of the bulk DOM is comprised of sugar cane DOM, whereas during heavy rainfall the amount increases to 31%, due to intensified drainage flow and soil erosion. In the estuary, 14-26% is of sugar cane origin. The sugar cane-derived component follows the mixing patterns of bulk DOM. 相似文献
95.
The Cariaco basin, located ∼40 km off the central part of the coast of Venezuela, is the largest (∼4000 km2) and bathymetrically deepest (1400 m BSL) Neogene fault-bounded basin within the right-lateral strike-slip plate boundary zone that separates the Caribbean and South American plates. Using subsurface geophysical data, we test two previously proposed tectonic models for the age, distribution and nature of east-west-striking, strike-slip faults, and basin-forming mechanism for the two main depocenters of the Cariaco basin. The earliest interpretation for the opening of the twin Cariaco depocenters by Schubert (1982) proposes that both depocenters formed synchronously by extension along transverse (north-south) normal faults at a ∼30-km-wide rhomboidally-shaped pull-apart basin between the right-lateral, east-west-striking, and parallel San Sebastian and El Pilar fault zones. A later model by Ben-Avraham and Zoback (1992) proposes that both depocenters formed synchronously by a process of ”transform-normal parallel extension”, or rifting in a north-south direction orthogonal to the east-west-striking and parallel strike-slip faults.We use more than 4000 km of 2D single- and multi-channel seismic data tied to 11 wells to map 5 tectono-stratigraphic sequences and to produce a series of structural and isopach maps showing how the faults that controlled both Cariaco depocenters evolved from Paleogene to the present. Comparison of fault and isopach maps for dated horizons from Paleogene to late Neogene in age show three main phases in basin development: 1) from middle Miocene to Pliocene, the West Cariaco basin formed as a rhomboidally-shaped pull-apart at a 30-km-wide stepover between the northern branch of the San Sebastian fault and the El Pilar fault zone; 2) during the early Pliocene, a new strike-slip fault transected the West Cariaco basin (southern branch of the San Sebastian fault) and caused extension to cease; and 3) during the early Pliocene to recent, a “lazy-Z” shaped pull-apart formed along the curving connection between the southern branch of the San Sebastian and El Pilar fault zones. 相似文献
96.
Di Virgilio Giovanni Evans Jason P. Di Luca Alejandro Grose Michael R. Round Vanessa Thatcher Marcus 《Climate Dynamics》2020,54(11):4675-4692
Climate Dynamics - Coarse resolution global climate models (GCMs) cannot resolve fine-scale drivers of regional climate, which is the scale where climate adaptation decisions are made. Regional... 相似文献
97.
Laura McFarlane Tranquilla April Hedd Chantelle Burke William A. Montevecchi Paul M. Regular Gregory J. Robertson Leslie Ann Stapleton Sabina I. Wilhelm David A. Fifield Alejandro D. Buren 《Estuarine, Coastal and Shelf Science》2010
Ocean climate change is having profound biological effects in polar regions. Such change can also have far-reaching downstream effects in sub-polar regions. This study documents an environmental relationship between High Arctic sea ice changes and mortality events of marine birds in Low Arctic coastal regions. During April 2007 and March 2009, hundreds of beached seabird carcasses and moribund seabirds were found along the east and northeast coasts of Newfoundland, Canada. These seabird “wrecks” (i.e. dead birds on beaches) coincided with a period of strong, persistent onshore winds and heavily-accumulated sea ice that blocked bays and trapped seabirds near beaches. Ninety-two percent of wreck seabirds were Thick-billed Murres (Uria lomvia). Body condition and demographic patterns of wreck murres were compared to Thick-billed Murres shot in the Newfoundland murre hunt. Average body and pectoral masses of wreck carcasses were 34% and 40% lighter (respectively) than shot murres, indicating that wreck birds had starved. The acute nature of each wreck suggested that starvation and associated hypothermia occurred within 2–3 days. In 2007, first-winter murres (77%) dominated the wreck. In 2009, there were more adults (78%), mostly females (66%). These results suggest that spatial and temporal segregation in ages and sexes can play a role in differential survival when stochastic weather conditions affect discrete areas where these groups aggregate. In wreck years, southward movement of Arctic sea ice to Low Arctic latitudes was later and blocked bays longer than in most other years. These inshore conditions corresponded with recent climate-driven changes in High Arctic ice break-up and ice extent; coupled with local weather conditions, these ice conditions appeared to be the key environmental features that precipitated the ice-associated seabird wrecks in the Low Arctic region. 相似文献
98.
Ezer Tal Carniel Sandro Amin Chabchoub de Camargo Ricardo Estrada-Allis Sheila N. Gao Guoping Greatbatch Richard J. Lermusiaux Pierre F. J. Liu Zhiyu Miyazawa Yasumasa Forster Alejandro Orfila Panickal Swapna Phillips Helen Pinones Andrea Stanev Emil Volker Christoph Xu Fanghua Young Emma 《Ocean Dynamics》2023,73(1):35-38
99.
Alejandro Feinstein 《Astrophysics and Space Science》1983,96(2):293-302
New photoelectric UBVRI data for stars in the young open cluster Tr 14 in the Great Carina Nebula (NGC 3372) are presented. The two-color diagram separates clearly the member from the nonmember stars. Thus, the membership of about 39 stars is suggested. Those located in the compact core of the cluster, have smaller reddening dispersion than those around it. No star appears above the Main Sequence at the faint end of the color-magnitude diagram. A distance modulus ofV 0?Mv=12.20±0.2 is obtained, which gives an age of about 5×106 yr. From only the photometry it is concluded to be slightly older than the nearby cluster Tr16. 相似文献
100.
The rip current hazard in Costa Rica 总被引:1,自引:1,他引:0