Video image analysis techniques

The spinning drop technique measures the shape of the oil drop in the flooding solution in a capillary tube. An automatic measuring system has been developed by combining a video-image analysis, an automatic recording system, and a computer for calculation of the interfacial tension [1865]. 

The microscopic high-speed video recording method has recently been developed further and used to investigate the combustion wave microstructure in the Ti-Si and Ti-N2 systems (Mukasyan et al., 1996 Hwang et al., 1997). The location of the combustion front was estimated using image analysis techniques, and its shape and propagation were characterized quantitatively. 

The feasibility of employing fluorescent tracers and video imaging analysis to quantify dermal exposure to pesticide applicators has been demonstrated under realistic field conditions. Six workers loaded a tracer with the organophosphate pesticide, diazinon, into air blast sprayers, and conducted normal dormant spraying in pear orchards. They were examined prior to and immediately after the application. UV-A illumination produced fluorescence on the skin surface, and the pattern of exposure was digitized with a video imaging system. Quantifiable levels of tracer were detected beneath cotton coveralls on five workers. The distribution of exposure over the body surface varied widely due to differences in protective clothing use, work practices and environmental conditions. This assessment method produced exposure values at variance with those calculated by the traditional patch technique. 

Girault and Schiffrin [6] and Samec et al. [39] used the pendant drop video-image method to measure the surface tension of the ideally polarized water-1,2-dichloroethane interface in the presence of KCl [6] or LiCl [39] in water and tetrabutylammonium tetraphenylborate in 1,2-dichloroethane. Electrocapillary curves of a shape resembling that for the water-nitrobenzene interface were obtained, but a detailed analysis of the surface tension data was not undertaken. An independent measurement of the zero-charge potential difference by the streaming-jet electrode technique [40] in the same system provided the value identical with the potential of the electrocapillary maximum. On the basis of the standard potential difference of —0.225 V for the tetrabutylammonium ion transfer, the zero-charge potential difference was estimated as equal to 8 10 mV [41]. 

R.S. Court, M.P.F. Sutcliffe, S.M. Tavakoli, Ageing of adhesively bonded joints—fracture and failure analysis using video imaging techniques. Int. J. Adhes. Adhes. 21, 455-463... 

For even better results, drop profile analysis can be applied instead of measuring the contact angle directly (axisymmetric drop shape analysis, ASDA Fig. 4.20). This technique extracts experimental drop profiles from video images while slowly increasing or decreasing the droplet volume [42, 43]. The best fit of experimental data with theoretical assumptions based on the Laplace equation of capillarity allows one to calculate the surface/inter-facial tension and subsequently the contact angle. Also droplet radius, droplet volume, and the contact area are computed. ADSA can therefore reveal... 

The information obtained in the OM normally concerns the size, shape and relative arrangement of visible features. Local measurement of optical constants such as the refractive index (Section 2.2.2) and the birefringence (Section 2.2.3) is also possible. Many techniques are used to enhance contrast, and thus make more of the structure visible. Images are typically recorded photographically, on video tape for the study of dynamic processes, or in a computer system for digital image analysis. 

The synthetic database of the forcing mechanism (wave climate) can also be obtained from any simulation process, like autoregressive models. Moreover, the data processing and simulation can be replaced by any technique capable of providing a sample of the different responses of the system. In the case of shoreline related problems, a sample with the position of the shoreline measured from video images would also be feasible for a shorter-term analysis. 

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