Absorption-line strengths of 18 late-type spiral galaxies observed with SAURON     

Katia Ganda  Reynier F. Peletier  Richard M. McDermid  Jesús Falcón-Barroso  P. T. de Zeeuw  Roland Bacon  Michele Cappellari  Roger L. Davies  Eric Emsellem  Davor Krajnovi&#;  Harald Kuntschner  Marc Sarzi  Glenn van de Ven † 《Monthly notices of the Royal Astronomical Society》2007,380(2):506-540

  相似文献   

Legal aspects of development on dolomite land in South Africa     

A. van Schalkwyk 《Environmental Geology》1998,36(1-2):167-169

 Dolomite rock formations underlie large areas of the Gauteng, North, North-West and Mpumalanga Provinces in South Africa. Sinkholes, subsidences and dolines that may form at any place and at any time on these formations pose a threat to the properties and lives of thousands of people who live and work there. Since much urban, industrial and mining development has taken place in these areas, and the demand for housing development is on the increase, the risk of surface damage must be minimized by means of proper site investigations, hazard and risk evaluation and selection of appropriate development. The legal aspects pertaining to development on dolomite land in South Africa and the requirements for geotechnical investigations as outlined in the various ordinances and acts are reviewed here. Received: 15 September 1996 · Accepted: 12 May 1998  相似文献   

Using vulnerability indicators to develop resilience networks: a similarity approach     

Stephanie E. Chang  Jackie Z. K. Yip  Shona L. van Zijll de Jong  Rebecca Chaster  Ashley Lowcock 《Natural Hazards》2015,78(3):1827-1841

  相似文献   

Biofuel scenarios in a water perspective: The global blue and green water footprint of road transport in 2030     

P.W. Gerbens-Leenes  A.R. van Lienden  A.Y. Hoekstra  Th.H. van der Meer 《Global Environmental Change》2012,22(3):764-775

Concerns over energy security and climate change stimulate developments towards renewable energy. Transport is expected to switch from fossil fuel use to the use of fuel mixtures with a larger fraction of biofuels, e.g. bio-ethanol and biodiesel. Growing biomass for biofuels requires water, a scarce resource. Existing scenarios on freshwater use usually consider changes in food and livestock production, and industrial and domestic activities. This research assesses global water use changes related to increasing biofuel use for road transport in 2030 and evaluates the potential contribution to water scarcity. To investigate water demand changes related to a transition to biofuels in road transport, the study combines data from water footprint (WF) analyses with information from the IEA APS energy scenario for 2030. It includes first-generation biofuels, bio-ethanol from sugar cane, sugar beet, sweet sorghum, wheat and maize, and biodiesel from soybean, rapeseed, jatropha and oil palm. Under the IEA APS scenario, the global biofuel WF will increase more than tenfold in the period 2005–2030. The USA, China and Brazil together will contribute half of the global biofuel WF. In many countries, blue biofuel WFs significantly contribute to blue water scarcity. The research provides a first exploration of the potential contribution of transport biofuel use to blue water scarcity. In 2030, the global blue biofuel WF might have grown to 5.5% of the totally available blue water for humans, causing extra pressure on fresh water resources. When biofuel use continues to expand after 2030, countries should therefore consider the water factor when investigating the extent to which biofuels can satisfy future transport energy demand.  相似文献   

Holocene vegetation and fire dynamics in the supra‐mediterranean belt of the Nebrodi Mountains (Sicily,Italy)     

Martina Bisculm  Daniele Colombaroli  Elisa Vescovi  Jacqueline F. N. van Leeuwen  Paul D. Henne  Julian Rothen  Giovanni Procacci  Salvatore Pasta  Tommaso La Mantia  Willy Tinner 《第四纪科学杂志》2012,27(7):687-698

High‐resolution pollen, macrofossil and charcoal data, combined with accelerator mass spectrometry ¹⁴C dating and multivariate analysis, were used to reconstruct Holocene vegetation and fire dynamics at Urio Quattrocchi, a small lake in the supra‐mediterranean belt in the Nebrodi Mountains of Sicily (Italy). The data suggest that after 10 000 cal a BP increasing moisture availability supported closed forests with deciduous (Quercus cerris, Fagus sylvatica and Fraxinus spp.) and evergreen (Quercus ilex) species. Species‐rich closed forest persisted until 6850 cal a BP, when Neolithic activities caused a forest decline and affected plant diversity. Secondary forest with abundant Ilex aquifolium recovered between 6650 and 6000 cal a BP, indicating moist conditions. From 5000 cal a BP, agriculture and pastoralism led to the currently fragmented landscape with sparse deciduous forests (Quercus cerris). The study suggests that evergreen broadleaved species were more important at elevations above 1000 m a.s.l. before ca. 5000 cal a BP than subsequently, which might reflect less human impact or warmer‐than‐today climatic conditions between 10 000 and 5000 cal a BP. Despite land use since Neolithic times, deciduous supra‐mediterranean forests were never completely displaced from the Nebrodi Mountains, because of favourable moist conditions that persisted throughout the Holocene. Reconstructed vegetation dynamics document the absence of any pronounced mid‐ or late‐Holocene ‘aridification’ trend at the site, an issue which is controversially debated in Italy and the Mediterranean region. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Planet earth: an encyclopedia of geology | A. Hallam (editor), 1977. Elsevier/Phaidon,Oxford, 320 pp., £ 7.95     

F.W.B. van Eysinga 《Earth》1978,14(2):203

  相似文献   

Flux comparison of Eulerian and Lagrangian estimates of Agulhas leakage: A case study using a numerical model     

Erik van Sebille  Peter Jan van Leeuwen  Arne Biastoch  Wilhelmus P.M. de Ruijter 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(3):319-327

Estimating the magnitude of Agulhas leakage, the volume flux of water from the Indian to the Atlantic Ocean, is difficult because of the presence of other circulation systems in the Agulhas region. Indian Ocean water in the Atlantic Ocean is vigorously mixed and diluted in the Cape Basin. Eulerian integration methods, where the velocity field perpendicular to a section is integrated to yield a flux, have to be calibrated so that only the flux by Agulhas leakage is sampled. Two Eulerian methods for estimating the magnitude of Agulhas leakage are tested within a high-resolution two-way nested model with the goal to devise a mooring-based measurement strategy. At the GoodHope line, a section halfway through the Cape Basin, the integrated velocity perpendicular to that line is compared to the magnitude of Agulhas leakage as determined from the transport carried by numerical Lagrangian floats. In the first method, integration is limited to the flux of water warmer and more saline than specific threshold values. These threshold values are determined by maximizing the correlation with the float-determined time series. By using the threshold values, approximately half of the leakage can directly be measured. The total amount of Agulhas leakage can be estimated using a linear regression, within a 90% confidence band of 12 Sv. In the second method, a subregion of the GoodHope line is sought so that integration over that subregion yields an Eulerian flux as close to the float-determined leakage as possible. It appears that when integration is limited within the model to the upper 300 m of the water column within 900 km of the African coast the time series have the smallest root-mean-square difference. This method yields a root-mean-square error of only 5.2 Sv but the 90% confidence band of the estimate is 20 Sv. It is concluded that the optimum thermohaline threshold method leads to more accurate estimates even though the directly measured transport is a factor of two lower than the actual magnitude of Agulhas leakage in this model.  相似文献   

Capillary hysteresis and gravity segregation in two phase flow through porous media     

Mitra  K.  van Duijn  C. J. 《Computational Geosciences》2022,26(1):101-114

We study the gravity driven flow of two fluid phases in a one dimensional homogeneous porous column when history dependence of the pressure difference between the phases (capillary pressure) is taken into account. In the hyperbolic limit, solutions of such systems satisfy the Buckley-Leverett equation with a non-monotone flux function. However, solutions for the hysteretic case do not converge to the classical solutions in the hyperbolic limit in a wide range of situations. In particular, with Riemann data as initial condition, stationary shocks become possible in addition to classical components such as shocks, rarefaction waves and constant states. We derive an admissibility criterion for the stationary shocks and outline all admissible shocks. Depending on the capillary pressure functions, flux function and the Riemann data, two cases are identified a priori for which the solution consists of a stationary shock. In the first case, the shock remains at the point where the initial condition is discontinuous. In the second case, the solution is frozen in time in at least one semi-infinite half. The predictions are verified using numerical results.

  相似文献   

Landslide detection in the Himalayas using machine learning algorithms and U-Net     

Meena  Sansar Raj  Soares  Lucas Pedrosa  Grohmann  Carlos H.  van Westen  Cees  Bhuyan  Kushanav  Singh  Ramesh P.  Floris  Mario  Catani  Filippo 《Landslides》2022,19(5):1209-1229

Landslides - Event-based landslide inventories are essential sources to broaden our understanding of the causal relationship between triggering events and the occurring landslides. Moreover,...  相似文献   

Pullout behavior of biocement–geosynthetic reinforcement system: a parametric study     

Hang  Lei  Gao  YuFeng  He  Jia  Li  Chi  Zhou  YunDong  van Paassen  Leon A. 《Acta Geotechnica》2022,17(12):5429-5439

Acta Geotechnica - In the biocement–geosynthetic system, biocement is combined with geosynthetic to increase the pullout resistance of the geosynthetic and thereby the stability of reinforced...  相似文献