Publication Notices

Notifications of the Newest Publications and Reports Released by ERDC

Contact ERDC Library

601.501.7632 - text
601.634.2355 - voice


ERDC Library Catalog

Not finding what you are looking for? Search the ERDC Library Catalog

Tag: Scattering
  • Numerical Analysis of Weak Acoustic Shocks in Aperiodic Array of Rigid Scatterers

    Abstract: Nonlinear propagation of shock waves through periodic structures have the potential to exhibit interesting phenomena. Frequency content of the shock that lies within a bandgap of the periodic structure is strongly attenuated, but nonlinear frequency-frequency interactions pumps energy back into those bands. To investigate the relative importance of these propagation phenomena, numerical experiments using the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation are carried out. Two-dimensional propagation through a periodic array of rectangular waveguides is performed by iteratively using the output of one waveguide as the input for the next waveguide. Comparison of the evolution of the initial shock wave for both the linear and nonlinear cases is presented.
  • PUBLICATION NOTICE: The Urban Ground-to-Ground Radio-Frequency Channel: Measurement and Modeling in the Ultrahigh Frequency Band

    ABSTRACT:  Ground-to-ground radio communication and sensing within the urban environment is challenging because line of sight between transmitter and receiver is rarely available. Therefore, radio links are often critically reliant on reflection and scattering from built structures. Little is known about the scattering strength of different buildings or whether such differences are important to the urban ground-to-ground channel. We tested the hypotheses that (1) diffuse scattering from built structures significantly impacts the urban channel and (2) scattering strength of urban structures varies with surface roughness and materials.  We tested these hypotheses by measuring urban channels in Concord, New Hampshire, and Boston, Massachusetts, and via channel-modeling efforts with three-dimensional representations of the urban environment. Direct comparison between measured and modeled channels suggest that both of these hypotheses are true. Further, it appears that ray-tracing approaches underestimate the complexity of urban channels because these approaches lack the physical processes to correctly assess the power incident on and scattered from built structures. We developed a radio-geospatial model that better accounts for incident power on both directly visible and occluded buildings and show that our model predictions com-pare more favorably with measured channels than those channels predicted via typical ray-tracing approaches.