Quantum Statistics of Three-Dimensional Vortex Filament in Superfluid 4He

The quantum statistics of three-dimensional vortex filament in superfluid ⁴ He is investigated by the use of path integral techniques. The free energy evaluated in the saddle point approximation decreases abruptly at a certain critical value of the applied superflow velocity. This critical behavior is in quantitative agreement with the experimental result of vortex nucleation by a moving ion. The dissipation effects are also discussed within the damped harmonic oscillator approximation.     

Rheological properties of iron oxide particle suspensions

Viscosities of γ-Fe₂O₃ dispersions in epoxy resin, phenol resin, and polyvinyl butyral solutions are measured at shear rate D from 19.2 to 384 sec^?1. Volume fraction of γ-Fe₂O₃ in these dispersions ranges from about 0.002 to 0.03. The concentration dependence of relative viscosity η/η_s is closely represented by the Mooney equation. From this equation, intrinsic viscosity [η] of suspensions is found to decrease from 46.1 at D = 19.2sec^?1 to 14 at D = 384 sec^?1 for epoxy resin solution. The high [η] value indicates the existence of flocs containing immobilized liquid. By increasing the shear rate, the average floc size is reduced to point where at an infinite shear rate, only small clusters or possibly particles remain. Of the three polymers, the lowest [η] value is obtained in the dispersion of the phenol resin solution.     

Degradation of polyacrylamide molecules in aqueous solutions by high-speed stirring

It has been observed that the viscosity of polyacrylamide (PAM) solution decreased with an increase in high-speed stirring time. The viscosities of PAM solutions decrease initially and then remain constant as the stirring time is increased. The final values depend on the stirring speed. This decrease was assumed to be due to a change in the dissolved state and/or the degradation of PAM molecules. It was discovered through experimentation that the molecular weight decreased, implying that the PAM molecules were degraded.     

A consideration of power density and hydrogen production and utilization technologies

The development of hydrogen (H₂) production systems and equipment utilizing hydrogen fuel is a key factor in the creation of a worldwide hydrogen energy network. The World Energy Network (WE-NET) project made significant progress in its development work in FY2002, especially in the critical area of hydrogen fueling stations. This report will examine some of the highlights of the FY2002 WE-NET project, and will also consider the impact of power density on fuel cell cost. Hydrogen production method also evaluated by scale merit (kW/m³).