Scattering of radiation by a large particle with a random rough surface     

Sonoyo Mukai  Tadashi Mukai  Richard H. Giese  Karin Weiss  Reiner H. Zerull 《Earth, Moon, and Planets》1982,26(2):197-208

Intensity and polarization of scattered light by an absorbing spherical particle with a random rough surface and with a radius larger than the wavelength of radiation are investigated. Multiple reflections of incident light on the rough surface are treated based on the multiple scattering theory.Within the limits of our approximation the model gives good agreement with typical scattering features by irregular shaped particles derived by microwave analogue experiments and laser measurements, namely a backward enhancement of the intensity, and a reduction of magnitude of polarization.Our treatment will be provide a powerful tool for studying scattering problems of interstellar and/or interplanetary grains as well as those of asteroids and the Moon.  相似文献   

Bioavailability of PAH in effluent water from an aluminium works evaluated by transplant caging and biliary fluorescence measurements of Atlantic cod (Gadus morhua L.)     

Jonny Beyer  Endre Aas  Hild Karin Borgenvik  Per Ravn 《Marine environmental research》1998,46(1-5)

Fixed wavelength fluorescence (FF) of bile was used as a biomarker for PAH exposure in fish caged adjacent to an aluminium works. After 30 days of caging, a 20–50 fold increase of pyrene fluorescence was found in groups caged adjacent to the works as compared to two control groups. The PAH uptake occurred mainly from suspended particles rather than from PAH contaminated sediments at the caging sites. Our results demonstrates the combined use of fish caging and bile-fluorescence measurements as a powerful field model for the monitoring of coastal waters subjected to PAH pollution.  相似文献   

Application of a mass-balance model to predict PCDD/F turnover in a Baltic coastal estuary     

O. Magnus Karlsson  J. Mikael Malmaeus  Sarah Josefsson  Karin Wiberg  Lars Håkanson 《Estuarine, Coastal and Shelf Science》2010

A dynamical, process-based mass-balance model was applied to quantify the transports of polychlorinated-p-dibenzodioxins and dibenzofurans (PCDD/Fs) to, within and from the Kallrigafjärden Bay, a coastal estuary in the Baltic Sea, and to predict the PCDD/F levels in the water and sediments of the bay. Before the modelling, a one-year sampling programme was implemented in 2007–2008 to measure the flows of PCDD/Fs in tributaries entering the system, the fluxes from the adjacent sea and the levels in water, sediment and fish within the estuary. The collected data set was used as input data to the model and for validation purposes.  相似文献   

Assessment of acceleration modelling for fluid‐filled porous media subjected to dynamic loading     

B. Lenhof  P. Kettil  K. Runesson  N.‐E. Wiberg 《国际地质力学数值与分析法杂志》2008,32(2):109-119

The purpose of this paper is to examine the importance of different possible simplifying approximations when performing numerical simulations of fluid‐filled porous media subjected to dynamic loading. In particular, the relative importance of the various acceleration terms for both the solid and the fluid, especially the convective contribution, is assessed. The porous medium is modelled as a binary mixture of a solid phase, in the sense of a porous skeleton, and a fluid phase that represents both liquid and air in the pores. The solid particles are assumed to be intrinsically incompressible, whereas the fluid is assigned a finite intrinsic compressibility. Finite element (FE) simulations are carried out while assuming material properties and loading conditions representative for a road structure. The results show that, for the range of the material data used in the simulations, omitting the relative acceleration gives differences in the solution of the seepage velocity field, whereas omitting only the convective term does not lead to significant differences. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Macroscopic diffusivity in concrete determined by computational homogenization     

Filip Nilenius  Fredrik Larsson  Karin Lundgren  Kenneth Runesson 《国际地质力学数值与分析法杂志》2013,37(11):1535-1551

Effective moisture and chloride ion diffusivity coefficients for concrete are determined by computational homogenization, where concrete is modeled on the mesoscale as a heterogenous three‐phase composite material. By imposing moisture and chloride ion gradients on a representative volume element, effective macroscale properties are obtained through finite element analysis. A parametric study of the effects of the ballast content was carried out. The numerical results correspond well with an estimate of the Hashin–Shtrikman type available in the literature. The computational homogenization strategy proposed here also includes the interfacial transition zone, and its influence on the effective diffusivity coefficients is assessed. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Quantitative methods for estimating flood fatalities: towards the introduction of loss-of-life estimation in the assessment of flood risk   总被引：1，自引：0，他引：1  

Manuela Di Mauro  Karin M. De Bruijn  Matteo Meloni 《Natural Hazards》2012,63(2):1083-1113

Risk, including flood risk, can be defined as ??the combination of the probability of an event and its consequences??. Assessing and managing the risk from flooding should explicitly include the estimation of impacts to people. Extensive research is currently ongoing looking at both quantitative and qualitative approaches for assessing flood impacts on people. Although there is some literature available on such approaches, examples of methodological and routinely applications of these methodologies as part of flood risk assessments are rare. This paper focuses on quantitative approaches for estimating impacts of flooding to people, notably on methods for assessing fatality numbers associated with flooding. Three methods for assessing losses of life are discussed in detail. The methods discussed here constitute the forefront of research in Canada, UK and The Netherlands. These methods provide an assessment of the physical consequences of flooding on people and can be used to introduce the impacts to people as quantitative metric for the assessment of flood risk. In this paper, the three methodologies are discussed and applied in a UK case study reproducing the 1953 East Coast flood event. This study aims to provide a comprehensive comparison on both the reliability and the applicability of the methods. We analyse possible added values on using of these methods in systematic analyses, aiming to provide guidelines for applying these methods for flood fatality risk assessment.  相似文献   

23 October 2011 Van (Turkey) earthquake   总被引：2，自引：0，他引：2  

Mustafa Erdik  Yaver Kamer  Mine Demircio?lu  Karin ?e?etyan 《Natural Hazards》2012,64(1):651-665

An earthquake of Mw7.2 on 23 October 2011 occurred in the Van region of Eastern Turkey. The main shock and long series aftershocks caused significant damage and claimed 644 lives. The particular features and the lessons learned are covered.  相似文献   

Palynological evidence for climatic and oceanic variability off NW Africa during the late Holocene     

Ilham Bouimetarhan  Lydie Dupont  Enno Schefuß  Gesine Mollenhauer  Stefan Mulitza  Karin Zonneveld   《Quaternary Research》2009,72(2):188-197

Pollen and organic-walled dinoflagellate cyst assemblages from core GeoB 9503-5 retrieved from the mud-belt ( 50 m water depth) off the Senegal River mouth have been analyzed to reconstruct short-term palaeoceanographic and palaeoenvironmental changes in subtropical NW Africa during the time interval from ca. 4200 to 1200 cal yr BP. Our study emphasizes significant coeval changes in continental and oceanic environments in and off Senegal and shows that initial dry conditions were followed by a strong and rapid increase in humidity between ca. 2900 and 2500 cal yr BP. After ca. 2500 cal yr BP, the environment slowly became drier again as indicated by slight increases in Sahelian savannah and desert elements in the pollen record. Around ca. 2200 cal yr BP, this relatively dry period ended with periodic pulses of high terrigenous contributions and strong fluctuations in fern spore and river plume dinoflagellate cyst percentages as well as in the fluxes of pollen, dinoflagellate cysts, fresh-water algae and plant cuticles, suggesting “episodic flash flood” events of the Senegal River. The driest phase developed after about 2100 cal yr BP.  相似文献   

Water-level variations in Lake Nhauhache, Mozambique, during the last 2,300?years     

Karin Holmgren  Jan Risberg  Johan Freudendahl  Mussa Achimo  Anneli Ekblom  Joao Mugabe  Elin Norstr?m  Sandra Sitoe 《Journal of Paleolimnology》2012,48(2):311-322

Stratigraphic variations in diatom composition and phytolith abundance in a sediment core from a small, hydrologically isolated waterbody, Lake Nhauhache, Mozambique, provide evidence of water-level fluctuations over the past ~2,300?years. Ten AMS radiocarbon dates on bulk sediment samples show that the lake came into existence about 2,300?years ago and that it has dried out since then, but only for brief time periods. Changes in the diatom assemblage composition indicate that lake level fluctuated in response to shifting humidity conditions. The changes reflect wetter conditions ca. 300 BC?CAD 800, more variable conditions between AD 800 and 1150, a distinct dry phase within the time span AD 1150?C1700 and a return thereafter to more humid conditions until present. There is general agreement between the Lake Nhauhache record and other records from the Southern Hemisphere summer rainfall region. This suggests that sediments from small interdunal lakes, which are abundant along the coast of southern Africa, provide reliable, regional paleoenvironmental information about an area from which more such data are needed.  相似文献   

Die Anwendung des Sutcliffeschen Entwicklungstheorems auf die Vb-Wetterlage vom 8. und 9. Oktober 1964     

Dr. Karin Dohnal 《Meteorology and Atmospheric Physics》1967,16(2-3):153-168

Zusammenfassung In der vorliegenden Arbeit wurde versucht, das Sutcliffesche Entwicklungstheorem auf dieV _b -Wetterlage vom 8. und 9. Oktober 1964 anzuwenden. Dabei wurde dieses Theorem einer Kritik unterzogen und allgemeiner gefaßt. Die Anwendung ergab, daß die Entwicklung selbst dadurch nicht richtig erfaßt werden konnte, wohl aber das weitere Verhalten der Zyklone nach ihrer Entwicklung. Für die Entwicklung selbst spielen offenbar die Winddrehung mit der Höhe und der vertikale Vorticitytransport eine entscheidende Rolle, die bei der vorliegenden Untersuchung nicht berücksichtigt wurden.

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Summary In this paper Sutcliffe's theorem of development is applied to theV _b -situation of October 8 and 9, 1964. Doing this the theorem has been critically revised and drafted in more generality. The application shows that the development cannot be explained by this theorem even in the more general drafting, however, the further behaviour of the cyclone after its development was in accordance to the theorem. For the development itself, obviously, the vertical windshear and the vertical transport of vorticity are dominating, both of which were not taken into consideration in the present investigation.

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Résumé Dans la présente étude, on cherche à appliquer le théorème de développement établi par Sutcliffe à la situation météorologique générale diteV _b -cyclone des 8 et 9 octobre 1964. On saisit cette occasion pour soumettre le dit théorème à la critique et pour lui donner une forme plus générale. Cette application a montré qu'il n'était pas possible de bien saisir par là le développement de la situation lui-même, mais, par contre de déterminer le comportement du cyclone après le dit développement. Il semble que la rotation des vents avec l'altitude et le transport vertical de la puissance tourbillonnaire (vorticity) jouent un rôle déterminant pour l'évolution elle-même de la situation. Ce rôle n'a cependant pas été pris en considération dans la présente étude.

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