Scanning and analysis of reconstructed holograms of a one-litre sample volume containing particles with varying sizes and shapes at high resolution is a major challenge. A completely automated system for analysing in-line holograms recorded in the ocean, which resolves particles larger than 10 µm, has been developed. It measures the three-dimensional coordinates of all the particles within the reconstructed volume and records their in-focus images. Scanning and analysing a reconstructed volume of about 500 cm 3 that contains several thousand particles takes about 5 h. The analysis consists of several steps. After compensating for exposure non-uniformities, the reconstructed images are scanned continuously with a digital camera. Then, superposition of thresholded images weighted by depth is introduced as a method compressing the 3D data to a plane to increase the efficiency of segmentation analysis. Subsequently, edge filtering is used for pinpointing the depth coordinate. To detect particles smaller than 50 µm, the reconstructed images are band-pass filtered optically. This approach is based on analysis that identifies interference of the reference beam with off-axis scattered light as the primary contributor to background noise. The scanning, thresholding and edge detection processes are repeated for the small particles. Additional procedures remove duplicate detections, and post-processing classifies the particles based on geometrical parameters. Sample data are presented.

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The focus of this paper is to discuss the unique challenges introduced through the use of unstructured grids in rotorcraft computational fluid dynamics (CFD)-computational structural dynamics (CSD) coupling. The use of unstructured grid methodology in CFD has been expanding because of the advantages in grid generation and modeling of complex configurations. However, the resulting amorphous distribution of the grid points on the rotor blade surface provides no information with regard to the orientation of the blade, in direct contrast to structured grid methodology that can take advantage of the ordered mapping of points to identify the orientation as well as simplifying airloads integration. A methodology has been developed and is described here, which now permits unstructured methods to be utilized for elastic rotary-wing simulations. This methodology is evaluated through comparison of the UH60A rotor with available flight test data for forward flight.

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