门限自回归模型在预测岩溶泉水流量中的应用——以桂林岩溶试验场为例   总被引：1，自引：0，他引：1  

戴爱德等  袁道先  蔡五田  P·比多 《中国岩溶》1988,7(3):259-264

门限自回归模型(TAR)是一种分段线性的非线性时间序列模型。因此,用于线性模型的定阶,参数估计,诊断性检验的BOX—JENKINS方法亦可用于TAR模型,与其它非线性模型相比具有计算简单,可用计算机自动建模的优点。在中法合作的中国桂林岩溶试验场,将它应用在岩溶泉系统的水量输入输出预测的研究方面,获得成功。   相似文献   

Effect of temperature on an alga‐grazer trophic transfer: A dual stable isotope (13C, 15N) labeling experiment          下载免费PDF全文

Erwann Legrand  Sophie Martin  Cédric Leroux  Pascal Riera 《Marine Ecology》2018,39(2)

In this study, we examined the impact of temperature on the carbon and nitrogen trophic transfers from a macroalga to a macro‐grazer by the use of dual ¹³C‐ and ¹⁵N‐labeling. Using an experimental approach in mesocosms, individuals of the urchin Psammechinus miliaris were maintained for 1 month at 17°C (mean summer temperature in the Bay of Brest) and at 20°C (maximum summer temperature) and fed with ¹³C‐ and ¹⁵N‐labeled Solieria chordalis. The results showed that the urchins’ ¹³C uptake was 0.30 µg¹³C g dry weight (DW)^?1 at 17°C and 0.14 µg¹³C g DW^?1 at 20°C at the end of the experiment. The lower uptake at the higher temperature may be attributed to a decrease in metabolic activity at 20°C, involving lower feeding and/or respiration rates. Conversely, no significant effect of temperature was detected on ¹⁵N uptake. At the end of the experiment, the urchins’ ¹⁵N uptake was 0.04 µg¹⁵N g DW^?1 at 17°C and 0.03 µg¹⁵N g DW^?1 at 20°C. This suggests that temperature may affect carbon and nitrogen trophic fluxes differently. The use of dual isotope labeling offers interesting prospects and needs to be further extended in order to better understand trophic interactions in marine communities and the consequences of current environmental changes, such as global warming.  相似文献   

Model-based optimization of source locations for 3D acoustic seismic full-waveform inversion     

Valérie Winner  Pascal Edme  Hansruedi Maurer 《Geophysical Prospecting》2023,71(1):3-16

Besides classical imaging techniques, full-waveform inversion is an increasingly popular method to derive elastic subsurface properties from seismic data. High-resolution velocity models can be obtained, and spatial sampling criteria are less strict than for imaging methods, because the entire information content of the seismic waveforms is used. As high operational costs arise from seismic surveys, the acquirable data volume is often limited by economic criteria. By selecting optimal locations for seismic sources, the information content of the data can be maximized, and the number of sources and thus the acquisition costs can be reduced compared with standard acquisition designs. The computation of such optimized designs for large-size 3D inverse problems at affordable computational cost is challenging. By using a sequential receiver-wise optimization strategy, we substantially reduce the computational requirements of the optimization process. We prove the applicability of this method by means of numerical 3D acoustic examples. Optimized source designs for different receiver patterns are computed for a realistic subsurface model, and the value of the designs is evaluated by comparing checkerboard inversion tests with different acquisition designs. Our examples show that inversion results with higher accuracy can be obtained with the optimized designs, regardless of the number of sources, the number of receivers, or the receiver distribution. Larger benefits of the optimized designs are visible when a sparse receiver geometry is used.  相似文献   

On dynamic sliding with rate- and state-dependent friction laws     

Pascal Favreau  Ioan R. Ionescu  & Michel Campillo 《Geophysical Journal International》1999,139(3):671-678

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The impact of internal waves on upper continental slopes: insights from the Mozambican margin (southwest Indian Ocean)     

Elda Miramontes  Gwenael Jouet  Estelle Thereau  Miguel Bruno  Pierrick Penven  Charline Guerin  Pascal Le Roy  Laurence Droz  Stephan J. Jorry  F. Javier Hernández-Molina  Antoine Thiéblemont  Ricardo Silva Jacinto  Antonio Cattaneo 《地球表面变化过程与地形》2020,45(6):1469-1482

Evidences of sedimentation affected by oceanic circulation, such as nepheloid layers and contourites are often observed along continental slopes. However, the oceanographic processes controlling sedimentation along continental margins remain poorly understood. Multibeam bathymetry and high-resolution seismic reflection data revealed a contourite depositional system in the Mozambican upper continental slope composed of a contourite terrace (a surface with a gentle seaward slope dominated by erosion) and a plastered drift (a convex-shape sedimentary deposit). A continuous alongslope channel and a field of sand dunes (mainly migrating upslope), formed during Holocene, were identified in the contourite terrace at the present seafloor. Seismic reflection data of the water column show internal waves and boluses propagating in the pycnocline near the upper slope. The channel and the dunes are probably the result of the interaction of the observed internal waves with the seafloor under two different conditions. The alongslope channel is located in a zone where intense barotropic tidal currents may arrest internal solitary waves, generating a hydraulic jump and focused erosion. However, upslope migrating dunes may be formed by bottom currents induced by internal solitary waves of elevation propagating landwards in the pycnocline. These small-scale sedimentary features generated by internal waves are superimposed on large-scale contouritic deposits, such as plastered drifts and contourite terraces, which are related to geostrophic currents. These findings provide new insights into the oceanographic processes that control sedimentation along continental margins that will help interpretation of palaeoceanographic conditions from the sedimentary record. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd  相似文献   

Large-scale in situ permeability tensor of rocks from induced microseismicity   总被引：10，自引：0，他引：10  

Sergee A. Shapiro  Pascal Audigane  & Jean-Jacques Royer 《Geophysical Journal International》1999,137(1):207-213

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A case study of impact‐induced hydrothermal activity: The Haughton impact structure,Devon Island,Canadian High Arctic     

Gordon R. Osinski  Pascal Lee  John Parnell  John G. Spray  Martin Baron 《Meteoritics & planetary science》2005,40(12):1859-1877

Abstract— The well‐preserved state and excellent exposure at the 39 Ma Haughton impact structure, 23 km in diameter, allows a clearer picture to be made of the nature and distribution of hydrothermal deposits within mid‐size complex impact craters. A moderate‐ to low‐temperature hydrothermal system was generated at Haughton by the interaction of groundwaters with the hot impact melt breccias that filled the interior of the crater. Four distinct settings and styles of hydrothermal mineralization are recognized at Haughton: a) vugs and veins within the impact melt breccias, with an increase in intensity of alteration towards the base; b) cementation of brecciated lithologies in the interior of the central uplift; c) intense veining around the heavily faulted and fractured outer margin of the central uplift; and d) hydrothermal pipe structures or gossans and mineralization along fault surfaces around the faulted crater rim. Each setting is associated with a different suite of hydrothermal minerals that were deposited at different stages in the development of the hydrothermal system. Minor, early quartz precipitation in the impact melt breccias was followed by the deposition of calcite and marcasite within cavities and fractures, plus minor celestite, barite, and fluorite. This occurred at temperatures of at least 200 °C and down to ?100–120 °C. Hydrothermal circulation through the faulted crater rim with the deposition of calcite, quartz, marcasite, and pyrite, occurred at similar temperatures. Quartz mineralization within breccias of the interior of the central uplift occurred in two distinct episodes (?250 down to ?90 °C, and <60 °C). With continued cooling (<90 °C), calcite and quartz were precipitated in vugs and veins within the impact melt breccias. Calcite veining around the outer margin of the central uplift occurred at temperatures of ?150 °C down to <60 °C. Mobilization of hydrocarbons from the country rocks occurred during formation of the higher temperature calcite veins (>80 °C). Appreciation of the structural features of impact craters has proven to be key to understanding the distribution of hydrothermal deposits at Haughton.  相似文献   

Structure of the upper mantle in the convex side of the New Hebrides island arc     

X. Goula  G. Pascal 《Geophysical Journal International》1979,58(1):145-167

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Dynamics analysis of a system of hinge-connected flexible bodies     

Madeleine Pascal 《Celestial Mechanics and Dynamical Astronomy》1987,41(1-4):253-274

The subject of this work is the dynamics of flexible space vehicles modelled by a chain of rigid and elastic bodies with tree structure. The aim of this investigation is to obtained an impedance matrix giving in frequency domain the response of the structure to external forces. We show that it is possible to obtain an expansion of this impedance matrix in terms of an infinite set of modal frequencies termed constrained modes and an expansion of the inverse of this impedance matrix in terms of an other set of modes. The work is a generalization of the theory made by Hugues [3] and others for systems with star structure.  相似文献   

Glass transitions and thermodynamic properties of amorphous SiO2, NaAlSinO2n+2 and KAlSi3O8     

Pascal Richet  Yan Bottinga 《Geochimica et cosmochimica acta》1984,48(3):453-470

A drop calorimetric study, between 900 and 1800 K, of amorphous SiO₂, NaAlSi₃O₈, NaAlSi₂O₆, NaAlSiO₄ and KAlSi₃O₈ shows the increase in heat capacity which results from glass transitions. For these glasses, the fictive temperature has a negligible effect on the heat capacity above room temperature, but it has an important influence on the enthalpy of formation as obtained from solution calorimetry. From these results and published Cp and enthalpy of solution data, several properties have been calculated: the enthalpies of fusion of high albite, nepheline, Jadeite and high sanidine, the thermodynamic functions of amorphous NaAlSi₃O₈ and KAlSi₃O₈ between 0 and 2000 K, and some mixing properties of liquids along the join SiO₂-NaAlSi₃O₈. The latter data suggest that these liquids behave more closely as athermal solutions than as regular solutions.  相似文献