On the detection of ultra high energy neutrinos with the Auger observatory     

K.S. Capelle  J.W. Cronin  G. Parente  E. Zas 《Astroparticle Physics》1998,8(4):321-328

We show that the Auger Air Shower Array has the potential to detect neutrinos of energies in the 10¹⁹ eV range through horizontal air showers. Assuming some simple conservative trigger requirements, we obtain the acceptance for horizontal air showers as induced by high energy neutrinos by two alternative methods and we then give the expected event rates for a variety of neutrino fluxes as predicted in different models which are used for reference.  相似文献   

Numerical simulation of high-velocity impact ejecta following falls of comets and asteroids onto the Moon     

N. A. Artemieva  V. V. Shuvalov 《Solar System Research》2008,42(4):329-334

High-velocity comet and asteroid impacts onto the Moon are considered and the material masses ejected after such impacts at velocities above the second-cosmic velocity for the Moon (2.4 km/s) are calculated. Although the results depend on a projectile type and the velocity and angle of an impact, it has been demonstrated that, on average, the lunar mass decreases with time. The Moon has lost about 5 × 10¹⁸ kg, that is, about one-hundredth of a percent of its mass, over the last 3.8–3.9 billion years. The ejection of lunar meteorites and lunar dust, rich in ³He, is considered as well. The results of the study are compared to the results of earlier computations and data on lunar meteorites.  相似文献   

Improving satellite image classification by using fractional type convolution filtering     

C. Quintano  E. Cuesta 《International Journal of Applied Earth Observation and Geoinformation》2010

This letter shows how conventional methods for satellite image classification can be improved by applying some filtering algorithms as a pre-classifying step. We will introduce a filtering scheme based on convolution equations of fractional type. The use of this kind of filter as a pre-classification step will be illustrated by classifying MODerate-resolution Imaging Spectroradiometer (MODIS) data to map burned areas in Mediterranean countries. The methodology we propose improved the estimations obtained by merely classifying the post-fire images (i.e. without filtering) in the study areas considered.  相似文献   

Four-neutrino mixing and Big-Bang Nucleosynthesis     

S. M. Bilenky  C. Giunti  W. Grimus  T. Schwetz 《Astroparticle Physics》1999,11(4):413-428

We investigate the Big-Bang Nucleosynthesis constraints on the elements of the neutrino mixing matrix which connect sterile with massive neutrino fields, in the framework of the two four-neutrino schemes that are favored by the results of neutrino oscillation experiments. We discuss the implications of these constraints for terrestrial short and long-baseline neutrino oscillation experiments and we present several possibilities of testing them in these experiments. In particular, we show that from the Big-Bang Nucleosynthesis constraints it follows that the transition is severely suppressed in short-baseline experiments, whereas its oscillation amplitude in long-baseline experiments is of order 1. We also propose a new parameterization of the four-neutrino mixing matrix U which is appropriate for the schemes under consideration.  相似文献