Comparison of theory and in situ observations for electron and ion distributions in the near wake of the explorer 31 and AE-C satellites     

Uri Samir  Ernest G. Fontheim 《Planetary and Space Science》1981,29(9):975-987

Measurements of electron density, plasma potential, and mean ion mass from the Explorer 31 satellite and measurements of ion current, plasma potential, and ion composition from the Atmosphere Explorer C (AE-C) satellite were used in a comparative study with theory regarding the charged particle distribution in the near wake of an ionospheric satellite. The theoretical wake model of Parker (1976) has been used in the study. It is shown that theory and experiment agree fairly well in the angle-of-attack range between 90 and 135°. In that angular range even the neutral approximation (which treats ions as if they were neutral particles thus ignoring the influence of the electric field) gives fair agreement with the measurements. In the maximum rarefaction zone (145 < θ < 180°), however, the theoretical model overestimates the measured ion depletion (AE-C measurements) by several orders of magnitude. A similar conclusion is drawn from the comparison between theory and the Explorer 31 electron measurements where the theory also significantly overestimates the electron depletion. The study indicates that the discrepancies are mainly due to the use of a steady-state theory and of a single ion equation (using a mean ion mass). It is recommended that improved agreement between theory and experiment be obtained by the use of the timedependent Vlasov-Poisson equations with separate equations for the various ion species.  相似文献   

Geochemical prospecting for thorium and uranium deposits: Vol. 16: Developments in Economic Geology. Robert W. Boyle,Elsevier Scientific Publishing Company,Amsterdam 1982, ix + 498 pp., Dfl. 200.00 (ca. US $70.00)     

Ernest E. Angino 《Journal of Geochemical Exploration》1984,20(1):99-100

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Special issue: 125?years of high-mountain research at Sonnblick Observatory (Austrian Alps)     

Hartmut Gra?l  Michael Hantel  Mathias W. Rotach  Ernest Rudel 《Theoretical and Applied Climatology》2012,110(4):489-490

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The climate tourism potential of Alpine destinations using the example of Sonnblick, Rauris and Salzburg     

Andreas Matzarakis  Martin H?mmerle  Elisabeth Koch  Ernest Rudel 《Theoretical and Applied Climatology》2012,110(4):645-658

The climate tourism potential of a region can be described by methods used in human biometeorology and applied climatology. Frequency analyses based on complex thermal bioclimatic indices (e.g. physiologically equivalent temperature) and diagrams of precipitation patterns based on thresholds offer new approaches of visualisation. An integral approach for tourism climatologic analyses is provided by the climate?Ctourism/transfer?Cinformation?Cscheme that also bases on frequency distributions of relevant factors and parameters which are important for a destination. The knowledge about the vertical variability of tourism climatologic factors is of high importance because of the several kinds of tourism activities affected by weather. The same holds for a quantification of extreme events like heat waves because of their possible effects on health and recreation over a year's course. The results show that the vertical gradient of bioclimatic and tourism-related parameters can be of value when developing strategies of adaption to climate change.  相似文献   

Scale mismatches and their ecological and economic effects on landscapes: A spatially explicit model     

Akiko Satake  Thomas K. Rudel  Ayumi Onuma 《Global Environmental Change》2008,18(4):768

Mismatches between the spatial scales of human decision-making and natural processes contribute to environmental problems such as global warming and biodiversity losses. People damage the environment through local activities like clearing land or burning fossil fuels, but the damages only become manifest at larger regional or global scales where no one pays for them. Payments for ecological services like carbon sequestration can correct for these damages caused by scale mismatches. This paper presents a spatially explicit land-use model to investigate the consequences of scale mismatches for pollination and carbon storage services and examine the effect of payment for only carbon storage services. The model integrates processes in multiple spatial scales ranging from the parcel level used by landowners’ decision about deforestation, to the larger scale used by animals to pollinate plants, and finally to the global scale where carbon storage services are supplied. We show that payment for carbon storage services can become an effective mechanism to protect forests at the same time that it creates inequities among landowners in income level.These findings suggest that market-based approaches that focus on conservation of a single ecosystem service may reproduce unequal power relations among landowners.  相似文献   

Excursion to Walton heath and Headley with special reference to the supposed Pliocene deposits: Saturday,June 11th, 1921     

George W. Young  Ernest Arthur Turner 《Proceedings of the Geologists' Association. Geologists' Association》1921,32(4):231-235

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Report of excursion to Borough Green: Weald research committee excursion     

E. Ernest S. Brown 《Proceedings of the Geologists' Association. Geologists' Association》1928,39(2):194-195

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Two-dimensional scattering of in-plane body waves due to a discontinuity in bedrock     

Ernest Heymsfield 《地震工程与结构动力学》1999,28(12):1651-1667

The direct boundary integral equation technique is used to study in-plane surface amplification of in-plane seismic body waves for the case of an inhomogeneity in a bedrock half-space. In the studied soil configuration, a soil layer rests on a rock half-space which includes a rock inclusion. The rock inclusion considered is a semi-infinite horizontal rock layer in which its upper boundary borders the soil layer. Materials in the soil–rock configuration are considered viscoelastic except for the section of the rock half-space below the level of the rock inclusion which is considered elastic. A parametric study is performed to determine controlling factors for surface displacement due to in-plane body waves. The study investigates varying the stiffness and the thickness of the rock inclusion for a range of frequencies and wave incidence angles. Anti-plane waves for this type of soil-rock configuration have been addressed in a previous article by Heymsfield (Earthquake Engng. Struct. Dyn. 28 : 841–855 (1999)). Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Simulation of the subsurface mobility of carbon nanoparticles at the field scale     

Erin Cullen  Denis M. O’Carroll  Ernest K. Yanful  Brent Sleep 《Advances in water resources》2010

The production and use of nanomaterials will inevitably lead to their disposal in the natural environment. To assess the risk that these materials pose to human and ecosystem health an understanding of their mobility and ultimate fate is essential. To date, however, relatively little research has been conducted on the fate of nanoparticles in subsurface systems. In this study the subsurface mobility of two carbon nanoparticles: nano-fullerenes (nC₆₀) and multi-walled carbon nanotubes (MWCNTs) is assessed. A two-dimensional finite element model was used to simulate the movement of these nanoparticles under a range of hydrologic and geological conditions, including a heterogeneous permeability field. The numerical model is based on colloid filtration theory (CFT) with a maximum retention capacity term. For the conditions evaluated the carbon nanotubes are much more mobile than nC₆₀ due to the smaller collector efficiency associated with carbon nanotubes. However, the mobility of nC₆₀ increased significantly when a maximum retention capacity term was included in the model. Model results also demonstrate that, for the systems examined, nanoparticles were predicted to be less mobile in heterogeneous systems compared to the homogeneous systems with the same average hydraulic properties.  相似文献   

Dynamique et modélisation des crues dans le bassin du Mono à Nangbéto (Togo/Bénin)     

Ernest Amoussou  Yves Tramblay  Henri S.V. Totin  Gil Mahé  Pierre Camberlin 《水文科学杂志》2013,58(11):2060-2071

Résumé

Les inondations des dernières années en Afrique de l’Ouest rendent nécessaire la prévision hydrologique pour réduire la vulnérabilité des populations. Nous avons étudié la dynamique des crues dans le bassin du Mono en amont du barrage de Nangbéto (Togo et Bénin) par des méthodes statistiques et déterministes. L’augmentation des précipitations au cours de la décennie 1990 et la mise en eau du barrage de Nangbéto en 1988 ont modifié le régime du Mono, dont les débits d’étiages ont augmenté. Les débits entrants et sortants du barrage sont équivalents, même lors des crues. Les maximums annuels des débits entrants peuvent être modélisés par une distribution des valeurs extrêmes (GEV) de type Fréchet, tandis que ceux des débits sortants, suivent une loi GEV de type Weibull (bornée). Le mécanisme dominant de génération des crues dans le bassin est la montée progressive des eaux associée à l’augmentation de la saturation des sols. L’analyse des débits de crue entre 1988 et 2010 n’a pas montré d’augmentation de la magnitude ou de la fréquence des crues. Le modèle GR4J reproduit bien les débits de crues en période calage, mais ces critères de performance se dégradent lorsque l’on s’en éloigne. Dans ces conditions, l’utilisation de ce modèle pour évaluer les risques futurs de crues serait hasardeuse et il est nécessaire d’envisager d’autres types d’approches.  相似文献