Experimental Determination of Reactions of Wind-Resistant Support of Circular Stacks in Various Configurations
Higher capacities of power plants together with increased awareness on environmental considerations have led to taller height of stacks. It is seen that strong wind can result in falling of stacks. So, aerodynamic consideration of stacks is very important in order to save the falling of stacks. One stack is not enough in industries and power sectors and two or three stacks are required for proper operation of the unit. It is very important to arrange the stacks in proper way to resist their downfall. The present experimental study concentrates on the mutual effect of three nearby stacks on each other at three different arrangements, viz. linear, side-by-side and triangular. The experiments find out the directions of resultant forces acting on the stacks in different configurations so that proper arrangement of supports can be made with respect to the wind directionality obtained from local meteorological data. One can also easily ascertain which stack is more vulnerable to wind in comparison to the others for a particular configuration. Thus, this study is important in studying the effect of wind force on three stacks in different arrangements and is very helpful in placing the supports in proper places in order to avoid failing of stack-like structures due to wind. Keywords—Stacks, relative positioning, drag and lift forces, resultant forces and supports.
Drag of circular cylinders in the atmospheric turbulence
A field experiment on the drag of circular cylinders was conducted during the approach of typhoon T9806 towards Kagoshima, Japan. A rotatable drag-measurement facility was developed which could orient itself perpendicular to the mean wind, and was deployed in an open field. Using this facility, we have successfully evaluated the drag coefficients Cd of circular cylinders. The results show that the Cd values of cylinders in a highly turbulent flow in the atmosphere are approximately equal to those in a smooth flow in wind tunnel experiments. This implies that the cylinder drags in a large-scale turbulence are close to the values in a smooth flow.
Urea removal strategies for dialysate regeneration in a wearable artificial kidney.
The availability of a wearable artificial kidney (WAK) that provides dialysis outside the hospital would be an important advancement for dialysis patients. The concept of a WAK is based on regeneration of a small volume of dialysate in a closed-loop. Removal of urea, the primary waste product of nitrogen metabolism, is the major challenge for the realization of a WAK since it is a molecule with low reactivity that is difficult to adsorb while it is the waste solute with the highest daily molar production. Currently, no efficient urea removal technology is available that allows for miniaturization of the WAK to a size and weight that is acceptable for patients to carry. Several urea removal strategies have been explored, including enzymatic hydrolysis by urease, electro-oxidation and sorbent systems. However, thus far, these methods have toxic side effects, limited removal capacity or slow removal kinetics. This review discusses different urea removal strategies for application in a wearable dialysis device, from both a chemical and a medical perspective.