Growth and damping of interfacial waves on a diffuse interface

The resonant interaction of surface and internal waves produces a nonlinear mechanism for energy transfer among wave components in oceans, lakes, and estuaries. In many field situations, the stratification may be well approximated by a two-layer fluid with a diffuse interface. The growth and damping rates of sub-harmonic interfacial waves generated by a surface wave through a three-wave resonant interaction are measured in the laboratory. These measurements are compared with theoretical predictions. A diffuse interface reduces the damping rate and increases the growth rate. The predicted growth rate provides excellent comparison with the laboratory measurements. The inclusion of the effects of a diffuse interface significantly improve the comparison.     

Horizon scanning for South African biodiversity: A need for social engagement as well as science

Ambio - A horizon scan was conducted to identify emerging and intensifying issues for biodiversity conservation in South Africa over the next 5–10 years. South African biodiversity...     

Spray Charging and Trapping Scrubber for Fugitive Particle Emission Control

The control of fugitive process emissions (FPE) with Spray Charging and Trapping (SCAT) scrubber was evaluated both theoretically and experimentally. The SCAT uses air curtain and/or jets to contain, convey, and divert the FPE into a charged spray scrubber.

Experiments were performed on an 8000 cfm bench-scale spray scrubber to verify the theory and feasibility of collecting fugitive particles with charged water spray. The effects of charge levels on drops and particles, nozzle type, drop size, gas velocity, and liquid/gas ratio on collection efficiency were determined experimentally. The results of the experiments and the comparison between theory and data are presented.

An air curtain was developed for conveying the FPE to the spray scrubber, deflecting the crosswind, and containing hot buoyant plume. The design and air flow field for the air curtain are presented.     

FF/C Scrubber Demonstration on a Secondary Metals Recovery Furnace

A flux force/condensation (FF/C) scrubbing system was built to control participate emissions from a secondary metals recovery furnace. Total mass penetration and fractional penetration measurements were made under several different operating modes. The performance of the demonstration scrubber was consistent with the results of previous studies on FF/C scrubbing. The system was generally capable of 90 to 95 % efficiency on particles with a mass median aerodynamic diameter of 0.75 µA. This efficiency was achieved with a 68 cm (27 in.) W.C. gas-phase pressure drop.     

The Effect of Analytical Method on Indicated Atmospheric SO2 Concentration

Atmospheric samples collected in several American cities were analyzed for SO₂ concentration using various analytical methods. The methods were: (1) electroconductivity, (2) West-Gaeke, (3) West-Gaeke with membrane prefdter, (4) West-Gaeke with glass-fiber prefilter, (5) hydrogen peroxide, (6) hydrogen peroxide with membrane prefilter, and (7) hydrogen peroxide with glass-fiber prefilter. The relationships among SO₂ data produced by these methods were evaluated statistically. Where statistical differences among methods, at the 95% confidence level, were determined then relationships were further delineated. Factors considered in these comparisons were: (1) location, {2) time of day, (8) concentration range, (4) particulate concentration, and (5) humidity. Laboratory evaluations of these methods show that each method is subject to different interfering substances. Laboratory evaluations of these methods show that each method is subject to different interfering substances. The relationship among methods obtained in these studies will complement these data and perhaps provide for further laboratory and field evaluation of methods used to measure SO₂. The relationship among SO₂ data produced by these methods should be useful in relating atmospheric SO₂ concentration to its effects and to those involved in establishing ambient air quality standards.     

Methodology for the Study of Public Attitudes Concerning Air Pollution

A significant element of a community's total air pollution picture is the “state of mind” of the people living in the area with respect to air pollution. The reasons why a study of public attitudes can be an important factor in planning an air pollution control program are briefly summarized. The methodology applied in one such study in the St. Louis Metropolitan area is described, and possible variations related to different scope, objectives and survey area characteristics are suggested.     

Flux Force/Condensation Scrubbing

Considerations for the engineering design of flux force/condensation (FF/C) scrubbers are reviewed. Fine par-ticulate removal in multiple sieve plate FF/C scrubbers is predicted, using mathematical design models. Results of experimental studies of two multiple sieve plate scrubbers for the removal of submicron particles are given. The published experimental data on FF/C scrubber performance are summarized. A preliminary analysis of the economics of FF/C scrubbers, compared to the conventional high energy scrubbers, defines the most favorable operating conditions for the application of FF/C scrubbers.