17,214 research outputs found
Research relative to angular distribution of snow reflectance/snow cover characterization and microwave emission
Remote sensing has been applied in recent years to monitoring snow cover properties for applications in hydrologic and energy balance modeling. In addition, snow cover has been recently shown to exert a considerable local influence on weather variables. Of particular importance is the potential of sensors to provide data on the physical properties of snow with high spatial and temporal resolution. Visible and near-infrared measurements of upwelling radiance can be used to infer near-surface properties through the calculation of albedo. Microwave signals usually come from deeper within the snow pack and thus provide depth-integrated information, which can be measured through clouds and does not relay on solar illumination.Fundamental studies examining the influence of snow properties on signals from various parts of the electromagnetic spectrum continue in part because of the promise of new remote sensors with higher spectral and spatial accuracy. Information in the visible and near-infrared parts of the spectrum comprise nearly all available data with high spatial resolution. Current passive microwave sensors have poor spatial resolution and the data are problematic where the scenes consist of mixed landscape features, but they offer timely observations that are independent of cloud cover and solar illumination
Pulsar motions from neutrino oscillations induced by a violation of the equivalence principle
We analize a possible explanation of the pulsar motions in terms of resonant
neutrino transitions induced by a violation of the equivalence principle (VEP).
Our approach, based on a parametrized post-Newtonian (PPN) expansion, shows
that VEP effects give rise to highly directional contributions to the neutrino
oscillation length. These terms induce anisotropies in the linear and angular
momentum of the emitted neutrinos, which can account for both the observed
translational and rotational pulsar motions. The violation needed to produce
the actual motions is completely compatible with the existing bounds.Comment: 6 pages, no figure
Cosmic Acceleration and Anisotropic models with Magnetic field
Plane symmetric cosmological models are investigated with or without any dark
energy components in the field equations. Keeping an eye on the recent
observational constraints concerning the accelerating phase of expansion of the
universe, the role of magnetic field is assessed. In the absence of dark energy
components, magnetic field can favour an accelerating model even if we take a
linear relationship between the directional Hubble parameters. In presence of
dark energy components in the form of a time varying cosmological constant, the
influence of magnetic field is found to be limited.Comment: 19 pages, 3 figures, submitted to EPJ plu
Alternative efficiency measures for multiple-output production
This paper has two main purposes. Firstly, we develop various ways of defining efficiency in the case of multiple-output production. Our framework extends a previous model by allowing for nonseparability of inputs and outputs. We also specifically consider the case where some of the outputs are undesirable, such as pollutants. We investigate how these efficiency definitions relate to one another and to other approaches proposed in the literature. Secondly, we examine the behavior of these definitions in two examples of practically relevant size and complexity. One of these involves banking and the other agricultural data. Our main findings can be summarized as follows. For a given efficiency definition, efficiency rankings are found to be informative, despite the considerable uncertainty in the inference on efficiencies. It is, however, important for the researcher to select an efficiency concept appropriate to the particular issue under study, since different efficiency definitions can lead to quite different conclusions
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