We have reconstructed a three-dimensional instantaneous temperature distribution inside the turbulent flame of a propane-air premix burner using multidirectional holographic interferograms by constructing a geometric model of the three-dimensional isothermal surfaces, and have read out the temperature values. To reconstruct this asymmetric temperature field, interference fringe data were acquired using an eight-directional Twyman-Green interferometer surrounding the object flame, and all data were simultaneously acquired. A ruby laser was used to obtain clear fringe patterns. The temperature distribution was reconstructed from the refractive index distribution, obtained from the fringe patterns, by a computed tomography technique using a convolution reconstruction algorithm. Isothermal profiles were calculated in horizontal cross sections from the temperature data. All of the multiple isotherms in each horizontal section were approximated with polygons and then stacked vertically to form polyhedra in a solid model format, having side facets with the corresponding isothermal values. Models, not only of the initial isothermal solids, but also of the solids resulting from multiple Boolean operations on them, were reconstructed to show the distribution in detail. This development will be of help in studying the local instantaneous structure of turbulent flames.
We have reconstructed a three-dimensional instantaneous temperature distribution inside a turbulent flame of a propane-air premixed burner using multidirectional holographic interferograms and visualized by constructing a geometric model of the three-dimensional isothermal surfaces. To reconstruct a three-dimensional asymmetric temperature field, the interference fringe data were acquired using an eight-directional Twyman-Green interferometer, over a full range of viewing angles, around the object flame, and all data are simultaneously acquired. A ruby laser, having a beam with a 20-30 ns pulse width, was used to obtain clear fringe patterns for this type of turbulent phenomena. The temperature distribution was reconstructed from the refractive index distribution, obtained from the fringe patterns, based on a computed tomography technique of a convolution reconstruction algorithm. Isothermal profiles were calculated in horizontal cross sections from the temperature data. All of the multiple isothermal contour lines in each horizontal section were approximated with polygons and then stacked up vertically to form polyhedra of the solid model format, having side facets of corresponding isothermal values. Computer graphics of the solid models, not only of the initial isothermal solids, but also of the solids resulting from multiple Boolean operations on them, were used to show the distribution in detail. This development will be of help in studying the local structure of the instantaneous turbulent flame and in integrating the experimental modeling with the numerical simulation.
A personal authentication method is proposed by integrating palmar geometry with the palmar and finger flexion crease analysis. A 900 x 900 image of either palm, placed freely on the flat transparent plate, is captured. Feature extraction involves: area, width and perimeter of the palm; areas, perimeters, skeletal axes and their lengths of the four fingers; shape factors of the palm and the fingers derived from the areas and the perimeters; aspect ratios; lengths of all of the finger flexion creases; intersecting points of the finger axes and the finger flexion creases; intersecting points of the finger axes and the major palmar flexion creases, those are prominent and typically classified into the thenar crease, the proximal transverse crease and the distal transverse crease. Some minor or secondary flexion creases are additionally detected. Orientation of the crease at each point of intersection is also detected. These metrics define the feature vectors for matching. We have tested the method on a limited set of palm images collected in a laboratory environment. Matching results, especially featured the oriented intersecting points of palmar creases, are encouraging. This integration with the palmar feature extraction will contribute to a more robust and reliable authentication system.
An automated modeling system that represents an object body by a solid model of polyhedral approximation was developed using multi-directional image inputs. The principle of this solid model generation is based on the calculation of viewing pyramids consisting of the image boundary and the corresponding focal point. Applications to the non-contacting three-dimensional measurement of the shape of irregular and complicated object such as a doll, a fish, a spiral shell, and a lemon, to the automated mesh generation for the boundary element analysis of the lemon, to the CAD of a tillage blade, and to the shape, deformation and motion analysis of an aerodynamic tuft, a small tracer particle, and an alcohol wick flame for the flow visualization are presented. It appears to have considerable utility in bio-mechanics and various industrial applications.
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