to enhance the understanding of the impact of obstacle buildings on pollution transportationand dispersion in the atmospheric boundary layer, it is necessary to know the atmospheric flow characteristics over terrains. wind flow characteristics in a boundary layer over a step-shaped cliff topography model with rough and smooth surfaces were studied numerically using computational fluid dynamics ...

In this paper, the effect of atmospheric turbulence on bit error probability in free-space optical CDMA scheme with Sequence Inverse Keyed (SIK) optical correlator receiver is analyzed. Here Intensity Modulation scheme is considered for transmission. The turbulence induced fading is described by the newly introduced gamma-gamma pdf[1] as a tractable mathematical model for atmospheric turbulence...

Atmospheric turbulence has significant influences on both the trajectories and strengths of wake vortices. In this paper, a quasi-wavelet method is used to generate a random atmospheric turbulence field based on the von Kármán spectrum, in which atmospheric turbulence is represented by groups of random eddies. An inviscid wake vortex system, out-of-ground effect or in-ground effect, is immersed...

The ergodic hypothesis is a basic hypothesis typically invoked in atmospheric surface layer (ASL) experiments. The ergodic theorem of stationary random processes is introduced to analyse and verify the ergodicity of atmospheric turbulence measured using the eddy-covariance technique with two sets of field observational data. The results show that the ergodicity of atmospheric turbulence in atmo...

to enhance the understanding of the impact of obstacle buildings on pollution transportationand dispersion in the atmospheric boundary layer, it is necessary to know the atmospheric flow characteristics over terrains. wind flow characteristics in a boundary layer over a step-shaped cliff topography model with rough and smooth surfaces were studied numerically using computational fluid dynamics ...

In this paper, we present a novel method to analyze the effects of atmospheric turbulence and misalignment fading (or pointing error) on performance of serial relaying M -ary pulse-position modulation (PPM) free-space optical (FSO) systems. Our study is more comprehensive than previous ones since we take into account the effect of beam size variation due to turbulence by using the partially coh...

In this paper the performance of a binary polarization shift keying (BPOLSK) modulated free space optical (FSO) link employing coherent detection in the presence of the atmospheric turbulence is investigated. First, a closed-form expression for the bit error rate (BER) of a BPOLSK-FSO system is presented taking into account the atmospheric turbulence-induced fading and noise. The BER performanc...

At the Naval Research Laboratory (NRL), we have developed a testbed for simulating atmospheric turbulence using Kolmogorov statistics for testing the correctibility of an Adaptive Optical System (AOS). In this testbed, a Liquid Crystal Spatial Light Modulator is being used to induce the atmospheric turbulence and a MEM deformable mirror is being used in the AOS to correct it. This atmospheric t...

Laser speckle can influence lidar measurements from a diffuse hard target. Atmospheric optical turbulence will also affect the lidar return signal. We present a numerical simulation that models the propagation of a lidar beam and accounts for both reflective speckle and atmospheric turbulence effects. Our simulation is based on implementing a Huygens-Fresnel approximation to laser propagation. ...