Linear stability analysis on surface tension‐induced instability of LiBr aqueous solution absorbing water vapor

Linear stability analysis is applied to the absorption of water vapor into lithium bromide aqueous solution film when a small amount of surfactant is added to the solution. The condition under which an instability occurs and the role of the surfactant are investigated. The analysis shows that the film becomes unstable at a positive Marangoni number when the heat transfer is more determining than the mass transfer. In contrast, when the mass transfer is more determining, the film becomes unstable at a negative Marangoni number. As for LiBr aqueous solution, mass transfer is more rate determining than heat transfer, so the instability is promoted and maintained when the Marangoni number is negative. In the case of film flow absorption, the analysis shows that the disturbance of the film flow becomes more unstable in the transverse direction than in the longitudinal direction as the Reynolds number increases. © 2000 Scripta Technica, Heat Trans Asian Res, 29(7): 581–597, 2000     

Growth of yttria stabilized zirconia thin films by metallo-organic, ultrasonic spray pyrolysis

Randomly and preferentially oriented thin films of yttria stabilized zirconia (YSZ) have been prepared on fused quartz substrates by ultrasonic spray pyrolysis using zirconium octylate and yttrium octylate as metallo-organic precursors at a substrate temperature of 873–1023 K. The as-deposited films composed of fine columnar grains were found to be crystalline and transparent with a cubic fluorite structure. With increasing substrate temperature the growth rate and diameter of the columnar grains increased and the crystal habit showed a preferential orientation at the (111) plane.     

Vanadium solid-salt battery: Solid state with two redox couples

We present the “vanadium solid-salt battery” (VSSB), which has high energy density, is low cost, is easily recycled, operates at ambient temperature, and has no requirement for special solvents. The VSSB contains two types of vanadium solid salts that are supported on carbon felts with a minimal amount of hydrosulfuric acid added to moisten the ion-exchange membrane. The optimized VSSB shows a cell potential of 1.34 V, excellent reproducibility for charging and discharging for nearly 100 cycles, a high energy efficiency (87%) and a high energy density (77 W h kg⁻¹ at 5 mA cm⁻² using the carbon felt XF208). The energy density is enhanced by 250-350% compared with conventional vanadium redox-flow batteries.     

Deformation near parallel cracks close to interface in bonded dissimilar plate

Tensile tests are carried out by using rectangular plate specimens extracted from the explosion clad plate. Artificial parallel cracks are made perpendicularly to the explosive interface in each specimen. When a tensile load is applied perpendicularly to the crack plane, strain, plastic deformation near cracks and crack opening displacement are examined by experiments as well as elasto-plastic finite element analysis. The effects of the material inhomogeneity, the change of material characteristics, the residual stress and the interaction between parallel cracks on the deformation behavior are revealed. The plastic zone around parallel cracks, at relatively low applied stress level, grows mainly ahead of and between two cracks. The interaction between parallel cracks on the crack opening displacement can be explained from the square of stress intensity factor at the low applied stress level and from the plastic deformation at the high applied stress level.