An Improved Method to Determine Particle Dispersion Width for Efficient Modeling of Turbulent Two‐Phase Flows

An improved approach is presented for the hybrid Eulerian‐Lagrangian modeling of turbulent two‐phase flows. The hybrid model consists of a nonlinear k–ε model for the fluid flow and an efficient Lagrangian trajectory model for the particulate flow. The improved approach avoids an empirical correlation required to determine the dispersion width for the existing Stochastic‐Probabilistic Efficiency Enhanced Dispersion (SPEED) model. The improved SPEED model is validated using experimental data for a poly‐dispersed water spray interacting with a turbulent annular air jet behind a bluff‐body. Numerical results for the number‐mean and Sauter‐mean droplet diameters, as well as mean and fluctuating droplet velocities are compared with the experimental data and with the predictions of other dispersion models. It is demonstrated that higher computational efficiency and smoother profiles of Sauter‐mean diameter can be obtained with the improved stochastic‐probabilistic model than with the eddy‐interaction model.     

Changes in vocal intensity in Parkinson's disease following pallidotomy surgery

The present study was designed to examine changes in vocal intensity following unilateral posteroventral pallidotomy (PVP) in a large sample of speakers with Parkinson's disease (PD) that exhibited a range of hypokinetic dysarthria. Twenty-five persons with PD were recorded using a variety of speech tasks, once prior to and once following PVP. The pre-PVP vocal SPL was subtracted from the post-PVP vocal SPL to derive a relative change in vocal SPL. Mildly dysarthric participants had significantly greater relative increases in vocal SPL following PVP than either moderately or severely dysarthric participants who had reduced vocal SPL following PVP. If future results follow those observed in the present data, mildly dysarthric Parkinson's patients may benefit most from unilateral PVP perhaps due to less overall destruction of the basal ganglia sensorimotor control circuits involved in oral facial functions, thus increasing the chances to observe improvements postsurgery.     

Coulomb energies and nuclear radii in the energy density formalism

The relation between Coulomb displacement energies,ΔE _c , andΔr=r _n -r _p , the difference between the rms radii of neutrons and protons in nuclei, is investigated within the energy density formalism (EDF). The variational equation, obtained by minimizing the Coulomb plus symmetry energies, is solved assuming the symmetry interaction is a simple functional of the local nuclear matter density. Varying parameters of the model, rather unique relation betweenΔE _c andΔr is obtained (within ±50 keV).ΔE _c isindependent ofr _ex, the rms radius of the excess neutrons distribution. Using the experimental values ofr _p and adjusting the model to reproduce the recent data onΔr (Δr∽~0.05 fm for⁴⁸Ca and²⁰⁸Pb), which are significantly smaller than those obtained from current Hartree-Fock calculations, the calculatedΔE _c agree with the experimental results. Using the value ofΔr～0.05 fm and the experimental values ofr _ex, a small compression (<0.02 fm) of the proton core in the analogue state relative to its parent state emerges, thus contributing an additional electrostatic term to the Coulomb displacement energy. The size of this relative core-compression effect depends on the values assumed forΔr andr _ex, it increases with the decreasing ofΔr and the increasing ofr _ex. IfΔr～0.05 fm the effect is large enough to remove the long standing Coulomb energy anomaly. The main result of the present work is the correlation betweenΔE _c andΔr, suggesting that the difficulties of current Hartree-Fock calculations in reproducing isotope shifts ofr _p , the small value ofr _n ?r _p and the values ofΔE _c may all be different manifestations of some missing residualp n effective interaction.     

Photopolymerization of Methyl Acrylate in Dimethyl Sulfoxide

Abstract

Methyl acrylate in dimethyl sulfoxide was polymerized by 2537 A ultraviolet light. The photo reaction exhibited zero-order kinetics for a given initial concentration and produced short chain polymers (M[Mbar]_W ～ 20,000). Low sulfur values of isolated polymers indicated no appreciable solvent incorporation during the polymerization.     

75th anniversary of Vladimir K. Baev

Anniversary Dates

75th anniversary of Vladimir K. Baev     

Existence of the Møller wave operators for V(r)=γ sin(μrα)rβ

We prove the existence of the Møller wave operators and the unitarity of the S operator for quantum mechanical potential scattering by potentials of the form

This includes the Special case $\text{V(r) =}\text{sin}\text{(r)}\text{r}$.