No abstract

This study deals with the photocatalytic treatment of saccharin (SAC) and bisphenol-A (BPA) under UV irradiation. For this purpose, novel submicronic anatase-rutile nanocomposite particles with tuned phase ratio produced by thermohydrolysis of acidic Ti(IV) solutions in the presence of controlled amounts of Sn(IV) were used. These catalysts were then assessed regarding their efficiency to degrade SAC or BPA, which are contaminants of increased environmental and health concern. The effect of various operating conditions, such as the anatase-rutile ratio (100:0, 85:15, 70:30), catalyst concentration (50-600 mg/L) and solute concentration (3-10 mg/L) was investigated. Furthermore, catalyst reuse-an important but little studied aspect-was assessed. Anatase-rutile nanocomposites were successfully prepared presenting good crystallinity and surface quality. Their activity was about the same for removing SAC or BPA from water. It was found that photocatalytic performance was increased with catalyst loading up to 400 mg/L. A further increase to 600 mg/L did not significantly enhance BPA removal, thus associating this tendency with screening effects. Also, photocatalytic efficiency was increased with initial solute concentration decrease. Organics degradation followed a pseudo-first order kinetic rate in terms of both SAC and BPA removal. The reproducibility of catalyst activity was assessed in three successive reuse cycles, where the removal percentage of initially 5 mg/L SAC was maintained as high as 70% at the end of the 3 rd cycle, in the presence of initially 400 mg/L anatase catalyst, and after 90 min of treatment. Finally, additional experimental runs were carried out with ultrasound cleaning (US) being applied to the reactant mixture at the beginning of each reuse cycle, but it was found to have no significant effect on treatment efficiency.

Externally slung loads and their mission applications are becoming more common on human and autonomously piloted air vehicles. Flight speed is often limited not by the performance envelope but by the danger of divergent load oscillations. Certifying this limiting speed for every load-vehicle combination, is a huge barrier to operations. The conservatism dictated by this uncertainty may itself be life-threatening in critical applications. Computing the dynamics of slung loads for a specific load/vehicle combination has been hindered by lack of knowledge on bluffbody aeromechanics. The prevailing top-down approach is to incorporate slung load aeromechanics calculations into large comprehensive aeromechanics codes for rotorcraft. We argue for a bottom-up approach. This allows on-the-fly system identification and dynamics simulation. The Slung Load Amplification Detector (SLAD) concept provides an on-board safety system to predict, detect, avoid and alleviate divergent oscillations. SLAD is based on a knowledge base derived from wind tunnel data and simulation results including canonical geometries, as well as practical shapes. Validation of simulation results against two practical test cases lends confidence. SLAD allows reliable distinction between pseudo and absolute divergence, permitting an increase of as much as 50% speed in safe flight speed, and guidance on active alleviation of oscillations.

No abstract