Holocene paleoenvironmental change inferred from two sediment cores collected in the Tibetan lake Taro Co     

Laug  Andreas  Haberzettl  Torsten  Pannes  Andre  Schwarz  Anja  Turner  Falko  Wang  Junbo  Engels  Stefan  Rigterink  Sonja  Börner  Nicole  Ahlborn  Marieke  Ju  Jianting  Schwalb  Antje 《Journal of Paleolimnology》2021,66(3):171-186

Journal of Paleolimnology - The Tibetan Plateau, also known as the “Water Tower of Asia” because of its function as a water storage and supply region, responds dramatically to modern...  相似文献   

A geomorphologic kinematic‐wave (GKW) model for estimation of floods from small alpine watersheds     

Dominique D. Brod  Vijay P. Singh  Andre Musy 《水文研究》1999,13(9):1391-1416

A geomorphologic kinematic‐wave (GKW) model was developed for simulation of extreme floods from small alpine catchments. The GKW model couples the kinematic‐wave theory and the geomorphologic representation of the catchment based on the Horton–Strahler ordering scheme. The model was tested on two small alpine catchments in Switzerland, and the agreement between simulated and observed floods was good. Care must however be taken with the computation of slope and roughness parameters. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Numerical simulation and seismic performance evaluation of buried pipelines rehabilitated with cured‐in‐place‐pipe liner under seismic wave propagation          下载免费PDF全文

Zilan Zhong  Andre Filiatrault  Amjad Aref 《地震工程与结构动力学》2017,46(5):811-829

The cured‐in‐place‐pipe (CIPP) liner technology involves installation of flexible polymeric composite liners coated with thermosetting resin to the inner surfaces of existing buried pipelines. This innovative technology provides an efficient, economic, and environmentally friendly alternative for rehabilitation of structurally compromised underground pipelines without expensive and disruptive excavation. However, the lack of analytical/numerical procedures to quantify the seismic performance of CIPP liner reinforced pipelines remains a barrier to the seismic design and rehabilitation of underground pipelines. This paper first develops an experimentally validated hysteretic model of ductile iron push‐on joints, reinforced with one particular type of CIPP liner under repeated axial loading. A numerical procedure is then proposed to systematically assess the seismic performance and fragility of straight buried pipelines incorporating push‐on joints and subjected to transient ground deformations. The numerical results indicate that CIPP liner‐reinforced pipelines exhibit favorable robust seismic performance with limited joint damage under high‐intensity transient ground deformations. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Effect of graded levels of dietary carbohydrate on growth,feed utilisation and intestinal microbial community structure in dusky kob Argyrosomus japonicus fed a pelleted diet     

NC Mabasa  PJ Britz  CLW Jones  A Nel 《African Journal of Marine Science》2018,40(3):267-277

The ability to utilise carbohydrates is limited for many predatory marine fishes. Graded levels of dietary carbohydrate (4.1–24.6%) were formulated using pregelatinised maize starch, to determine optimal levels for dusky kob Argyrosomus japonicus, an emerging mariculture finfish for which pelleted feeds are being developed. Specific growth rate increased with an increase in the carbohydrate level up to 16.72%, after which it declined. Feed utilisation followed a similar trend, with the best feed conversion ratio (1.28) and protein efficiency ratio (1.76) recorded at 16.4% carbohydrate. Lipid vacuolisation of the hepatocytes was evident in all livers examined, with melano-macrophage aggregates in those of fish fed 24.6% carbohydrate suggesting starvation. Gut bacterial community profiles were variable but were not influenced by dietary carbohydrate level and differed mostly between fish fed trout feed prior to the trial and those fed experimental diets containing starch. The dusky kob were able to clear glucose from their blood when fed up to 16.4% carbohydrate, but glucose removal was not achieved at 24.6% carbohydrate. In conclusion, dusky kob has a limited ability to utilise cooked starch as a carbohydrate source, which may be included in pelleted feed at 16.4% without adverse effects. For this species, levels of dietary carbohydrate above this may result in symptoms consistent with physiological breakdown, including reduced growth, reduced feed intake and feed conversion efficiency, prolonged hyperglycaemia, liver pathology and altered microbial communities in the foregut.  相似文献   

Identification of low frequency waves in the vicinity of the terrestrial bow shock     

M.A. BalikhinO.A. Pokhotelov  S.N. Walker  M. Andre 《Planetary and Space Science》2003,51(11):693-702

In this paper, methods for the determination of the wave mode for low frequency waves based on observed differences in phase are reviewed. Examples, using measurements made in the terrestrial foreshock and magnetosheath, are used to illustrate the application of these methods. The use of advance methods such as NARMAX modelling or genetic algorithms to identify the plasma wave mode is also discussed.  相似文献   

The Nu Expression for Probabilistic Data Integration   总被引：4，自引：0，他引：4  

Evgenia I. Polyakova  Andre G. Journel 《Mathematical Geology》2007,39(8):715-733

The general problem of data integration is expressed as that of combining probability distributions conditioned to each individual datum or data event into a posterior probability for the unknown conditioned jointly to all data. Any such combination of information requires taking into account data interaction for the specific event being assessed. The nu expression provides an exact analytical representation of such a combination. This representation allows a clear and useful separation of the two components of any data integration algorithm: individual data information content and data interaction, the latter being different from data dependence. Any estimation workflow that fails to address data interaction is not only suboptimal, but may result in severe bias. The nu expression reduces the possibly very complex joint data interaction to a single multiplicative correction parameter ν ₀, difficult to evaluate but whose exact analytical expression is given; availability of such an expression provides avenues for its determination or approximation. The case ν ₀=1 is more comprehensive than data conditional independence; it delivers a preliminary robust approximation in presence of actual data interaction. An experiment where the exact results are known allows the results of the ν ₀=1 approximation to be checked against the traditional estimators based on assumption of data independence.  相似文献   

In-flight Performance of the Advanced Camera for Surveys CCDs     

Mark Clampin  Marco Sirianni  George F. Hartig  Holland C. Ford  Garth D. Illingworth  Bill Burmester  William Koldewynd  Andre R. Martel  Adam Riess  Ronald J. Schrein  Pamela C. Sullivan 《Experimental Astronomy》2002,14(2):107-115

The Advanced Camera for Surveys (ACS), installed in the Hubble Space telescope in March 2002, will significantly extend HST's deep, survey imaging capabilities. ACS has met, or exceeded, all of its key performance specifications. In this paper we briefly review the in-flight performance of the instrument's CCD detectors and preview early ACS science observations. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Quantitative antimony speciation in shooting-range soils by EXAFS spectroscopy   总被引：1，自引：0，他引：1  

Andreas C. Scheinost  Andre Rossberg  Irene Xifra  Ann-Kathrin Leuz  C. Annette Johnson 《Geochimica et cosmochimica acta》2006,70(13):3299-3312

The Sb speciation in soil samples from Swiss shooting ranges was determined using Sb K-edge X-ray absorption spectroscopy (XAS) and advanced statistical data analysis methods (iterative transformation factor analysis, ITFA). The XAS analysis was supported by a spectral data set of 13 Sb minerals and 4 sorption complexes. In spite of a high variability in geology, soil pH (3.1-7.5), Sb concentrations (1000-17,000 mg/kg) and shooting-range history, only two Sb species were identified. In the first species, Sb is surrounded solely by other Sb atoms at radial distances of 2.90, 3.35, 4.30 and 4.51 Å, indicative of metallic Sb(0). While part of this Sb(0) may be hosted by unweathered bullet fragments consisting of PbSb alloy, Pb L_III-edge XAS of the soil with the highest fraction (0.75) of Sb(0) showed no metallic Pb, but only Pb²⁺ bound to soil organic matter. This suggests a preferential oxidation of Pb in the alloy, driven by the higher standard reduction potential of Sb. In the second species, Sb is coordinated to 6 O-atoms at a distance of 1.98 Å, indicative of Sb(V). This oxidation state is further supported by an edge energy of 30,496-30,497 eV for the soil samples with <10% Sb(0). Iron atoms at radial distances of 3.10 and 3.56 Å from Sb atoms are in line with edge-sharing and bidentate corner-sharing linkages between Sb(O,OH)₆ and Fe(O,OH)₆ octahedra. While similar structural units exist in tripuhyite, the absence of Sb neighbors contradicts formation of this Fe antimonate. Hence the second species most likely consists of inner-sphere sorption complexes on Fe oxides, with edge and corner-sharing configuration occurring simultaneously. This pentavalent Sb species was present in all samples, suggesting that it is the prevailing species after weathering of metallic Sb(0) in oxic soils. No indication of Sb(III) was found.  相似文献   

Fluid geochemistry of natural manifestations from the Southern Poroto–Rungwe hydrothermal system (Tanzania): Preliminary conceptual model     

Manuëlla Delalande  Laurent Bergonzini  Fabrizio Gherardi  Massimo Guidi  Luc Andre  Issah Abdallah  David Williamson 《Journal of Volcanology and Geothermal Research》2011,199(1-2):127-141

The South Poroto–Rungwe geothermal field, in the northern part of the Malawi rift, Tanzania divides in two main areas. The relatively high altitude northern area around the main Ngozi, Rungwe, Tukuyu and Kyejo volcanoes, is characterised by cold and gas-rich springs. In contrast, hot springs occur in the southern and low-altitude area between the Kyela and Livingstone faults. The isotopic signature of the almost stagnant, cold springs of the Northern district is clearly influenced by H₂O–CO_2(g) exchange as evidenced from negative oxygen-shifts in the order of few deltas permil. In contrast, the isotopic signature of waters discharged from the hot springs of the Southern district is markedly less affected by the H₂O–CO_2(g) interaction. This evidence is interpreted as an effect of the large, permanent outflow of these springs, which supports the hypothesis of a regional-scale recharge of the major thermal springs. Measurements of carbon isotope variations of the dissolved inorganic carbon of waters and CO_2(g) from the Northern and Southern springs support a model of CO_2(g)-driven reactivity all over the investigated area. Our combined chemical and isotopic results show that the composition of hot springs is consistent with a mixing between (i) cold surface fresh (SFW) and (ii) Deep Hot Mineralised (DHMW) Water, indicating that the deep-originated fluids also supply most of the aqueous species dissolved in the surface waters used as local potable water. Based on geothermometric approaches, the temperature of the deep hydrothermal system has been estimated to be higher than 110 °C up to 185 °C, in agreement with the geological and thermal setting of the Malawi rift basin. Geochemical data point to (i) a major upflow zone of geothermal fluids mixed with shallow meteoric waters in the Southern part of the province, and (ii) gas absorption phenomena in the small, perched aquifers of the Northern volcanic highlands.  相似文献   

Natural and forced air temperature variability in the Labrador region of Canada during the past century     

Robert G. Way  Andre E. Viau 《Theoretical and Applied Climatology》2015,121(3-4):413-424

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