Similarity between chaos analysis and frequency analysis of pressure fluctuations in fluidized beds

In literature the dynamic behavior of fluidized beds is frequently characterized by spectral analysis and chaos analysis of the pressure fluctuations that are caused by the gas-solids flow. In case of spectral analysis, most often the power spectral density (PSD) function is quantified, for example, by the frequency at the largest power and/or by the power-law fall-off at the higher frequencies. In case of chaos analysis, most often the correlation entropy (or Kolmogorov entropy) is used to characterize the fluidized bed dynamics. In this paper, it is shown theoretically that a relationship exists between the correlation entropy and the PSD function. This relationship is experimentally verified by a large set of experimental pressure fluctuation data from slugging, bubbling, and circulating fluidized beds. It is shown that the correlation entropy is linearly proportional to the average frequency that is obtained from the PSD function. As the average frequency can be directly interpreted in terms of the physical phenomena underlying the pressure fluctuations, the average frequency is suggested as a first, simple, characteristic of fluidized bed dynamics. (C) 2004 Elsevier Ltd. All rights reserved

Strategies for rare-event detection:An approach for automated fetal cell detection in maternal blood

This article explores the feasibility of the use of automated microscopy and image analysis to detect the presence of rare fetal nucleated red blood cells (NRBCs) circulating in maternal blood. The rationales for enrichment and for automated image analysis for "'rare-event" detection are reviewed. We also describe the application of automated image analysis to 42 maternal blood samples, using a protocol consisting of one-step enrichment followed by immunocytochemical staining for fetal hemoglobin (HbF) and FISH for X- and Y-chromosomal sequences. Automated image analysis consisted of multimode microscopy and subsequent visual evaluation of image memories containing the selected objects. The FISH results were compared with the results of conventional karyotyping of the chorionic villi. By use of manual screening, 43% of the slides were found to be positive (greater than or equal to 1 NRBC), with a mean number of 11 NRBCs (range 1-40). By automated microscopy, 52% were positive, with on average 17 NRBCs (range 1-111). There was a good correlation between both manual and automated screening, but the NRBC yield from automated image analysis was found to be superior to that from manual screening (P = .0443), particularly when the NRBC count was >15. Seven (64%) of 11 XY fetuses were correctly diagnosed by FISH analysis of automatically detected cells, and all discrepancies were restricted to the lower cell-count range. We believe that automated microscopy and image analysis reduce the screening workload, are more sensitive than manual evaluation, and can be used to detect rare HbF-containing NRBCs in maternal blood