Characterization of Supersonic Compressible Fluid Flow Using High-Speed Interferometry.

This paper presents a very effective interference technique for the sensing and researching of compressible fluid flow in a wind tunnel facility. The developed technique is very sensitive and accurate, yet easy to use under conditions typical for aerodynamic labs, and will be used for the nonintrusive investigation of flutter in blade cascades. The interferometer employs a high-speed camera, fiber optics, and available "of-the-shelf" optics and optomechanics.

THE INFLUENCE OF PINHOLES IN WATERPROOFING MATERIALS ON THE VALUE OF THE RADON DIFFUSION COEFFICIENT.

This article focuses on an experimental study of the influence of imperfections on the value of the radon diffusion coefficient of various waterproofing materials. Microscopic holes were made by a thin tip or by a microdrill bit to imitate the real damage that can be incurred during construction. To determine the change in the radon diffusion coefficient, each waterproofing material was measured five times.

APPLICABILITY OF VENTILATION SYSTEMS FOR REDUCING THE INDOOR RADON CONCENTRATION.

An analysis is presented of the ability of balanced mechanical ventilation systems to reduce the radon concentration in residential buildings efficiently. The analysis takes into account the following parameters: radon supply rate into the building, ventilation intensity, required indoor radon concentration and energy consumption. It is shown that the applicability of ventilation systems is limited mainly by energy consumption.

Radon diffusion coefficients and radon resistances of waterproofing materials available on the building market.

This paper presents radon diffusion coefficient values and radon resistance values determined for 650 widely-used waterproofing materials divided into 29 groups according to their chemical composition. The reliability of two different approaches for determining the radon resistance is discussed, and differences between the two approaches are identified. A comparison between the radon resistances of waterproofing materials and the requirements prescribed by various building standards indicates that some requirements are unnecessarily strict.

A NEW APPROACH TO THE ASSESSMENT OF RADON BARRIER PROPERTIES OF WATERPROOFING MATERIALS.

New definitions of the radon resistance and radon transmittance of waterproofing materials are introduced. They are based on the real steady-state radon distribution within the materials. Both quantities can therefore be considered as suitable parameters for the design of radon-proof insulations.