Nir Shiloah - Academia.edu (original) (raw)

Papers by Nir Shiloah

&lt;p&gt;Clouds are a severe disturbance in a very wide range of applications, su... more &lt;p&gt;Clouds are a severe disturbance in a very wide range of applications, such as aviation, and solar energy, and in ground based, airborne, and satellite observations. The ability to accurately predict cloud-base heights (CBH) using the weather models is of crucial importance&lt;/p&gt;&lt;p&gt;In recent years, information on CBH has been added as an integral part of the output of the European Operational Model, the Integrated Forecasting System (IFS) of the European Center for Medium-Range Weather Forecasts (ECMWF).&lt;/p&gt;&lt;p&gt;In order to examine the quality of the IFS forecasts, a CBH comparison was made in this work for low-level clouds at the eastern basin of the Mediterranean, between the IFS model predictions, observations from different meteorological satellites - VIIRS and CALIPSO, ceilometer observations at two sites in Israel - Beit Dagan (Coastal Plain) and Jerusalem (Mountainous area), and aviation weather report data from airports.&lt;/p&gt;&lt;p&gt;The comparison shows that there is a very good agreement between CBH IFS predictions, and ground observations from ceilometers (in most months the difference is less than 25% of the CBH), and a good agreement in cloud cover between IFS forecast and observations of aviation weather reports.&lt;/p&gt;&lt;p&gt;The comparison also shows that there is a good agreement between CBH IFS predictions, and CALIPSO satellite measurements (the difference is on average less than 35% of the CBH, and an excellent 95% fit if CBH measurements are paired compared. Similar comparison of VIIRS satellite observations with CBH IFS predictions, shows good agreement too (the difference is less than 20% of the CBH).&lt;/p&gt;

Selected Topics in Electronics and Systems, 2009

ABSTRACT

AIP Advances, 2018

Understanding the multi-mass model and sound generation of vocal fold oscillation AIP Advances 9,... more Understanding the multi-mass model and sound generation of vocal fold oscillation AIP Advances 9, 105002 (2019);

Journal of Quantitative Spectroscopy and Radiative Transfer, 2019

SPIE Proceedings, 2003

ABSTRACT We consider here the electromagnetic wave scattering by a long and thin-wire helical par... more ABSTRACT We consider here the electromagnetic wave scattering by a long and thin-wire helical particle. In contrast to several previous theoretical works, we adopt here the Mie theory to this case. In the present work a long helical particle is considered as a hollow cylinder with a thin non-homogeneous membrane for which the periodical boundary conditions are imposed.

Journal of Quantitative Spectroscopy and Radiative Transfer, 2003

In this paper a simple algorithm is presented for calculating light scattering by a multi-layered... more In this paper a simple algorithm is presented for calculating light scattering by a multi-layered spheroid for both normal and oblique incidence. Results of several numerical tests are given. They present the extinction e ciency for di erent aspect-ratio spheroids in comparison with that of the proper multi-layered sphere and cylinder.

Journal of Quantitative Spectroscopy and Radiative Transfer, 2010

This paper studies characteristics of the electro-magnetic wave scattering by a long helical part... more This paper studies characteristics of the electro-magnetic wave scattering by a long helical particle in cases of oblique incidence with different polarizations. The dependence of the resonant peaks and the phase function on the incidence angle is analyzed for different values of helix parameters. The analysis is based on the model developed by the authors and presented in previous publications.

Journal of Quantitative Spectroscopy and Radiative Transfer, 2007

ABSTRACT The scattering properties of metal-coated fibers are studied. It is shown that an optima... more ABSTRACT The scattering properties of metal-coated fibers are studied. It is shown that an optimal thickness of the metal layer exists, for which the extinction efficiency can significantly exceed the extinction efficiency of uncoated homogeneous metal fibers of identical size. At the same time the scattering efficiency of coated fibers remains lower than that of the homogeneous ones.

Journal of Quantitative Spectroscopy and Radiative Transfer, 2001

The calculation procedure for the scattering coe cients appearing in the Mie theory is discussed ... more The calculation procedure for the scattering coe cients appearing in the Mie theory is discussed for a case of multilayered particles with a large size parameter. There are two di erent aspects to the problem. The ÿrst aspect concerns a case where the imaginary part of the size parameters remains small. Shown here is the possibility for avoiding the canonical recommendations which prescribe using both upward and downward recursions for di erent types of Bessel functions. We have justiÿed the procedure based on the upward recursions only where results are as stable as those in the canonical one. The second aspect concerns the case with a large imaginary part of the size parameter. The calculation procedure for a multilayered particle fails in such a case because of 0=0-type uncertainty. However, this problem can be overcome by using the proper asymptotic relations at crucial points. The numerical results are demonstrated for spherical and cylindrical multilayered particles.

Applied Optics, 2000

3. Moroz, A. (2005). A recursive transfer-matrix solution for a dipole radiating inside and outsi... more 3. Moroz, A. (2005). A recursive transfer-matrix solution for a dipole radiating inside and outside a stratified sphere. Annals of Physics, 315 (2), 352-418.

Journal of Quantitative Spectroscopy and Radiative Transfer, 2008

ABSTRACT We consider here the electromagnetic scattering by a long helical particle made from a t... more ABSTRACT We consider here the electromagnetic scattering by a long helical particle made from a thin (in comparison to the wavelength) wire. In contrast to several previous theoretical works, we adopt here the algorithm developed for scattering by a multi-layered fiber. In the present work, the helical particle is considered as a hollow cylinder with a thin non-homogeneous membrane for which periodical boundary conditions are imposed.

SPIE Proceedings, 1999

ABSTRACT The operation of laser radar in an automotive collision avoidance system under poor visi... more ABSTRACT The operation of laser radar in an automotive collision avoidance system under poor visibility conditions is analyzed. The equations were formulated to calculate (1) the signals returned to a laser radar system by a reflecting target positioned at a given range and (2) signals caused by the scattering of laser radiation by atmospheric particles only. The dependence of calculated signals on the density and the scattering properties of the atmospheric medium on one hand and on the geometry of the system on the other hand was studied. The multiple scattering processes were included in these calculations, and the polarization properties of the calculated signals were analyzed. An experimental verification of the theoretical results in a clear atmosphere and in a dense atmospheric environment has been performed. Good agreement was achieved only when multiple scattering was included in the theory. It is shown that multiple scattering is the main contributor to the signals received from the medium. Utilization of the results of this work can reduce significantly the very high false alarm rate typical for dense atmospheric conditions where successful anti- collision system performance is most crucial.

Journal of Quantitative Spectroscopy and Radiative Transfer, 1999

The purpose of the paper is to develop a formalism for solving the problem of scattering of elect... more The purpose of the paper is to develop a formalism for solving the problem of scattering of electromagnetic waves by a tilted, in"nite, multilayered cylinder. The approach allows us to obtain the Mie scattering coe$cients without involving matrix calculations. This method provides the basis for constructing an e$cient algorithm for the case of a multilayered cylinder, extending the procedure developed for a multilayered sphere. For the case of a cylinder, such a procedure does not follow directly from the boundary conditions, but requires a special mathematical justi"cation. The proof is presented in this study.