Defect of the five-thirds law using the Wiener-Hermite expansion

Application of the refined Wiener-Hermite expansion with moderate to high Reynolds numbers Re to homogeneous, isotropic turbulence is presented. The results show a defect to Kolmogorov's five-thirds law, increase in the absolute value of the exponent comparable with many theoretical predictions. Midrange spectra up to fluctuation Reynolds numbers of 10⁸ show little, if any, dependence of the defect on Re, as long as the initial spectra do not deviate too far from their equilibrium states. The renormalization scheme has also been proven to have no effect on the final shape of the spectrum.     

The effect of curvature variation on the scattering from rough surfaces

The general high-frequency, rough-surface reflection process is treated by the method of stationary phase. In particular, the principle of stationary phase is applied to each of the local reflection events, which appear to depend on surface curvature as well as slope. However, we show that the number of reflecting highlights also depends on curvature and cancels the curvature dependence. These results agree fully with those obtained by Beckmann and Spizzichino for the special case of the Gaussian process.     

On the simple-source theory of sound from statistical turbulence

A theory for the generation of aerodynamic sound, stated in terms of convected simple sources and dipoles, is presented. The sources are found to depend upon convective derivatives of the hydrodynamic pressure within the turbulent source region. The results are similar to earlier efforts involving simple sources, sometimes called dilatational sources. The results are modified for effects involving measurements on moving flows. The theory shows explicitly the refractive effects of shear flow within the source region, as well as of temperature changes (if any) within the source region. The oscillating cylinder problem is discussed and the results of the present theory are found to agree with those obtained by Lauvstad using a matched asymptotic expansion for the same problem. The theory is used to predict the temperature dependence of sound power for hot jets.Consultant for Bolt Beranek and Newman, Inc.     

Development of field-deployable instrumentation based on “antigen–antibody” reactions for detection of hemorrhagic disease in ruminants

Development of field-deployable methodology utilizing antigen–antibody reactions and the surface plasmon resonance (SPR) effect to provide a rapid diagnostic test for recognition of the blue tongue virus (BTV) and epizootic hemorrhage disease virus (EHDV) in wild and domestic ruminants is reported. A Spreeta chip, which utilizes microelectronic technology to implement the SPR effect, is shown to possess sufficient sensitivity and operating speed to detect either BTV and EHVD antigens or antibodies in real time. The biosensor consists of an outer active surface layer comprised of either an antibody or antigen immobilized by covalent bonds through several other organic layers including a self assembled monolayer to a gold surface. Parallel experiments were run on the biosensor surface using either a home-built high resolution SPR instrument or a low resolution solid state Spreeta SPR chip. Both instruments were capable of monitoring the antigen–antibody reaction used to selectively detect the presence of BTV and EHDV viral pathogens. Results for the antibody and antigen reactive layers with antigen or antibody solutions as well as the modeling of these layers are discussed. The characteristics of these biosensors – specificity and time of reaction – were assessed. The antibody surface biosensors exhibited a high degree of specificity, even when using low resolution instrumentation. The time of analysis was under 20 min, which was the arbitrary exposure time.     

Stochastic representation of nearly-Gaussian,nonlinear processes

The use of polynomial functionals of the white noise process is discussed for the treatment of nonlinear random processes. It is noted that such treatments are useful for nearly-Gaussian processes. Applications of such representations to nonlinear systems and to nonlinear fluid mechanics problems (turbulence) are reviewed.