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.
Straked in-line steel stacks with low mass-damping parameter☆
In wind-tunnel tests on a single stack and a row of five slender stacks with a very low mass-damping parameter, Mδ = 2Mδs/ϱD2 = 3.3, the locking-in and buffeting effects have been investigated. It has been shown that the influence of fitting a cone on the lower part of the stack is negligible for the vortex-exciting oscillation. The effectiveness of strakes on the upper part of the cylindrical stack depends on the mass-damping parameter, i.e. on the nondimensional oscillation amplitude. Below a specific limit of Mδ the strakes lose their damping effect and the oscillation increases to a magnitude similar to that for the plain stack. 
 
For stacks in a row arrangement the dynamic response is distinctly increased by buffeting. For distance ratios of the stacks a/D ≌10, the enhancement is nearly 70%. Larger distance-ratios give lower enhancement, and for a/D ⩾ 23 the buffeting effect may be neglected. 
 
The use of a dynamic damping-absorber of mass 2% of the total stack mass leads to very low amplitudes y0 less than 0.02D, due to a 30 times larger effective damping.
Rotating dialysis cell as in vitro release method for oily parenteral depot solutions.
The purpose of the study was to investigate an in vitro release method based on a rotating dialysis cell for parenteral oil depot formulations using different model conditions and test formulations. The total amount of drug released from the rotating dialysis cell was in accordance with the theoretical values calculated from the partition coefficients. The release rates were shown to depend on the total amount of drug available for the release process and to follow first order kinetics. The rotating dialysis cell has a potential as in vitro release method for characterization of oily depot formulations for parenteral administration.