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481.
482.
Interstellar extinction is presented in a unified picture from the infrared (=104 nm or 10 m) to the X-rays (E=1.25 nm or 10 keV), as a cross-section normalized per hydrogen atom. Analytical expressions for the cross-section covering the whole range are cited or given in the Appendix for computational purposes.
Résumé L'extinction interstellaire est présentée de manière unifiée, de l'infrarouge (104 nm ou 10 m) jusqu'aux rayons X (1.25 nm ou 10 keV) comme une section efficace normalisée par atome d'hydrogène. Des expressions analytiques de cette section efficace couvrant tout le domaine sont eitées ou données dans l'appendice pour permettre des calculs à l'ordinateur.
  相似文献   
483.
If no correction is performed, the inertia of the sensors for temperature and humidity in research aircraft leads to an error in the calculation of turbulent fluxes. Simple considerations give an estimation of the order of magnitude of these errors. A simple method for the in-situ estimation of temperature sensor inertia is given.  相似文献   
484.
中国大陆东部及海域地壳-上地幔结构研究c   总被引:8,自引:0,他引:8       下载免费PDF全文
中国大陆东部及海域(98~150E,5~50N)位于欧亚大陆和太平洋两大板块的衔接地带,且深受来自印度洋板块活动的影响.本文利用该区域内的35个数字地震台记录的面波资料,采取多重滤波技术等时频分析方法,求得了1252条路径上基阶瑞利波的频散曲线,然后将研究区域划分为11的网格,通过Occam反演方法求得了10~158s周期范围内基阶瑞利波群速度在研究区域内的分布.这些速度分布大致反映了不同深度范围介质S波速度的横向变化情况.利用求得的纯路径频散,进一步反演得到了青藏高原东部——太平洋、南海——蒙古两个剖面的S波速度随深度的变化,发现研究区内的横向不均匀性直到400km仍很明显,各构造单元的划分与速度结构有明显的关系.   相似文献   
485.
DPFT is a lumped approach for operational flash flood forecasting, based on the unit hydrograph. Using a multi-event alternating iterative algorithm, it identifies a robust and stable average transfer function and a consistent set of effective rainfall series associated with each event at the same time. This key ingredient allows an objective calibration of different loss functions, relating gauged precipitation and effective rainfall. A case study based on an operational French basin (545 km2) is presented. Three lumped production functions have been calibrated and compared. The results show that more elaborate models of loss functions must be proposed, and some possible directions for this are pointed out.  相似文献   
486.
The project of an ultradeep drill hole (KTB) in the Oberpfalz area at the western margin of the Bohemian Massif has completed a pilot drill hole to a depth of 4000.1 m in April 1989. This well is situated only about 200m away from the main drill hole aimed at 10 km depth where drilling started in September 1990. The cores of the pilot well have a diameter of 9.4 cm or 10.16 cm, respectively. In addition to cores and cuttings there was also mud available for geochemical, petrological and some geophysical measurements. The pilot drill hole has a core recovery length of as much as 3042.6 m (about 76%), among which 193.1 m were obtained by rotary drilling and 2849.5 m by wireline drilling. Several petrophysical parameters were measured in a specially established field laboratory at the drill site immediately after sampling in order to obtain as good as possible in-situ values. Results for the following parameters are reported: density, natural gamma ray activity, velocities of seismic longitudinal and shear waves, thermal conductivity, electrical resistivity, natural remanent magnetization, magnetic susceptibility, porosity and inner surface. The methods of measurement are characterized briefly and the results of the pilot drill hole are presented and discussed in connection with the lithology and the geophysical anomalies, which have been observed on the surface.  相似文献   
487.
Tetracycline marking of coregonids at the time of egg fertilization   总被引:2,自引:0,他引:2  
Tetracycline marking of otoliths can be achieved by osmotic importation at fertilization when hardening is conducted in tetracycline solutions. Marks produced are recognizable even in fish of catchable size without a very extensive otolith preparation. The method can contribute to estimations of stocking efficiency and to discern recruits of natural and artificial reproduction.  相似文献   
488.
A semi-probabilistic approach to the seismic hazard assessment of Greece is presented. For this reason, a recent seismotectonic model for shallow and intermediate depth earthquake sources, based on historical as well as on instrumental data, was used. Different attenuation formulae were proposed for the macroseismic intensity and the strong ground motion parameters for the shallow and the intermediate focal depth shocks. The data were elaborated in terms of McGuire's computer program, which is based on the Cornell's method.A grid of equally spaced points at 20 km distance was made and the seismic hazard recurrence curves for various parameters of the seismic intensity was estimated for each point. Finally, seismic hazard maps for the area of Greece were compiled utilizing the entire range of recurrence curves. These maps depict areas of equal seismic hazard and for every area the analytical relations of the typeSI =f(Tm), whereSI is a seismic intensity parameter andTm is the mean return period, were determined.  相似文献   
489.
Presented are the results of the winter 2014 radiophysical expedition, within the framework of which the Baikal ice cover was investigated by electromagnetic methods. The primary objectives the expedition were to detect irregularities in the ice cover, such as cracks and thawing steamed holes in the ice, and to determine the ice thickness and structure in the area of the thawing holes by the GPR sounding method. We used in the experiments the OKO-2 ground-penetrating radar (GPR) of the decimeter band and the nanosecond radar with the wavelength of 3 cm. The measurements were made carried out from the Khivus hovercraft and from the UAZ automobile. The ice thickness of Lake Baikal was determined by non-contact electromagnetic measurement methods. Radargrams of reflected signals from the ice cover are presented. Radar patterns of reflected signals from artificial irregularities of the ice cover were obtained by the short-pulse radar method. The concept of radiophysical monitoring is suggested, which provides a means of determining the ice cover parameters of a water body with high spatial resolution. We present an integral approach to investigating the conditions of the ice cover in order to integrate different physicochemical methods for diagnosing the objects studied. A further development of the concept of integrated ice cover research, and the creation of the monitoring network involves solving a number of scientific and engineering tasks that include developing physical models and information and measurement systems as well as the rationale for an integrated monitoring network.  相似文献   
490.
Résumé

Nous confirmons, par l’utilisation d’une base de données géochimiques sur un très grand nombre de roches magmatiques actuelles ou récentes ordonnées selon des critères géotectoniques rigoureux, la validité de la démarche de discrimination géotectonique, par les éléments traces, pour des laves et plutons contenant moins de 55% de Si02. Nous précisons les limites des champs discriminants, dans le diagramme Th-Tb-Ta, et montrons leur position non aléatoire vis à vis du point représentatif du Manteau Primordial, chaque contexte pouvant être caractérisé par un mode de fractionnement particulier des systèmes Th-Ta et Tb-Ta. Ceci suggère que la discrimination géotectonique reflète à la fois l’hétérogénéité des sources des magmas et la permanence des caractères de la (des) source(s) dans un contexte donné. Cette démarche est appliquée à une quinzaine de métabasites (amphibolites et éclo-gites) échantillonnées lors d’une campagne de cartographie de la chaîne panafricaine du Togo et supposées représentatives de différentes unités lithostructurales. Par leurs caractéristiques géochimiques, ces échantillons s’apparentent aux basaltes associés au système Afar/Mer Rouge ou aux tholéiites continentales. Aucun ne présente les signatures géochimiques des laves émises en contexte de convergence de plaques ou des basaltes de rides médio-océa-niques “normales” (“N-type MORB”). Ces résultats suggèrent la mise en place du magmatisme préorogénique dans un contexte de rift continental mais n’apportent pas d’argument en faveur de la résorption d’un vaste domaine océanique dans cette partie de la chaîne panafricaine.  相似文献   
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