in this paper the reflection coefficient of electromagnetic wave incidence on the walls of the buildings and obstacles that occurs in mobile communication path was modified by solving the riccati nonlinear equations. for this purpose, the building walls are assumed inhomogeneous layers where their permittivity changes as function of the wall thickness. using this reflection coefficient, a new p...

This paper describes an improved model for multiple building diffraction modeling based on the uniform theory of diffraction (UTD). A well-known problem in conventional uniform theory of diffraction (CUTD) is multiple-edge transition zone diffraction. Here, higher order diffracted fields are used in order to improve the result; hence, we use higher order diffraction coefficients to improve a hy...

Using the geometrical optics approximation, a theoretical prediction of the deflection angle correlation of a laser beam propagating in a hot turbulent jet is found as a functional form of the turbulent spectrum of the refractive index fluctuations. By applying the modified Von Karman model and Tatarskii model, the structure coefficient of the refractive index and the deflection angle correlati...

Diffraction methods [13] continue to provide the main tool for the structure analysis of solids. The corresponding inverse problem of determining a structure from its diffraction is difficult and, in general, does not define a structure uniquely. Kinematic diffraction, an approximation that is reasonable for X-ray diffraction where multiple scattering effects can be neglected, is well suited fo...

We investigate the errors due to the use of unphysical values of light quark masses in lattice extractions of αs. A functional form for the pion mass dependence of the quarkonium mass splittings (∆m) is given as an expansion in mπ/(4πfπ) and mπrB, where rB is the quarkonium Bohr radius. We find that, to lowest order, ∆m ≃ A + Bmπ, where the scale of B is given by f 2 πr 3 B. To order m 4 π ther...

$EVWUDFW A simple “Bread and Peace” model shows that aggregate votes for President in postwar elections were determined entirely by weighted-average growth of real disposable personal income per capita during the incumbent party’s term and the cumulative numbers of American military personnel killed in action as a result of U.S. interventions in the Korean and Vietnamese civil wars. The model i...

The collisional damping of satellite wakes at the edge of the Encke gap of Saturn's rings is studied using N-body simulations. The self-gravity of the ring particles is neglected. The wake damping rate is determined as a function of ring optical depth, particle size, and the coefficient of restitution of colliding particles. The amplitude decay of the wakes is nonuniform and is not a simple fun...

Ringing, the high-frequency response of a structure to relatively low-frequency waves, has been a great concern in offshore engineering. To investigate this phenomenon, we solve the third-harmonic diffraction problem using a three-dimensional higher-order panel method in the low-frequency range. In this thesis, the boundary integral equations are derived from two different theories , based on c...

We investigate theoretically the nonlinear propagation of the limited diffraction Bessel beam in nonlinear media, under the successive approximation of the KZK equation. The result shows that the nth-order harmonic of the Bessel beam, like its fundamental component, is radially limited diffracting, and that the main beamwidth of the nth-order harmonic is exactly 1/n times that of the fundamental.