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We provide experimental results from the scattering of light by deformed liquid droplets and droplets with inclusions. The characterization of droplet deformation could lead to improved measurement of droplet size as measured by commercial aerodynamic particle-sizing instruments. The characterization of droplets with inclusions can be of importance in some industrial, occupational, and military aerosol monitoring situations. The nozzle assembly from a TSI Aerodynamic Particle Sizer was used to provide the accelerating flow conditions in which experimental data were recorded. A helium-neon laser was employed to generate the light-scattering data, and an externally triggered, pulsed copper vapor laser provided illumination for a droplet imaging system arranged orthogonal to the He-Ne scattering axis. The observed droplet deformation correlates well over a limited acceleration range with theoretical predictions derived from an analytical solution of the Navier-Stokes equation. [C] 2000 Optical Society of America OCIS codes: 290.0290, 290.5820, 290.5850.

Two independent definitions for quantifying measurement accuracy and two limiting schemes for their assessment are examined in this paper. Gauss' mean square error MSE is compared to the symmetric-range accuracy A, describing the range of measurements about a measurand. Both measures of accuracy account for systematic error (bias) and imprecision so as to quantify the closeness of estimates to the actual values being measured. Remarkably, it is found that the accuracy functions are closely equivalent for most method applications. Furthermore, details are presented on how to compute confidence limits on measurement accuracy so as to account for error in method evaluation. The confidence limits are qualitatively different in the case that the method undergoes extensive initial evaluation in comparison to a continual re-evaluation at each method application. To this end the statistical theories of tolerance as well as more familiar types of confidence intervals are applied. Published by Elsevier Science Ltd on behalf of British Occupational Hygiene Society. [ABSTRACT FROM AUTHOR]

Errors of estimates of concentration in the diffusive sampling of analytes weakly bound to finite-thickness sorbents are investigated both theoretically and experimentally. Experimental data are presented for sampling concentration pulses of trichloroethylene. using a column of activated charcoal as sorbent. Analysis indicates that analyte loss results in errors in estimates of 8-h time-weighted averages (TWA) between —17 and 51%, the extreme values corresponding to short pulses occurring at the beginning or end of the sampling period, respectively. Experiments were also conducted on pulse sampling using a sampler which employs a liquid (in this case, water) column as sorbent. Both acetone (weakly bound) and methanol (more strongly bound) were studied so as to cover a range of physical phenomena. Limits of several mathematical approximations are discussed within the framework of these experiments. [ABSTRACT FROM PUBLISHER]

Presents a study which evaluated the mass stability of the materials used in the construction of samplers with internal cassettes for the gravimetric measurement of inhalable aerosol exposures. Methods and materials; Results and discussion; Conclusions.