1,721,026 research outputs found
Biodegradation of PAH (polycyclic aromatic hydrocarbon) using immobilized phanerochaete chrysosporium
No full textA catalytic burner using propane and toluene alternately for the drying of textile coatings
No full textThis study aims to develop a low-temperature catalytic burner using propane and toluene alternately as a fuel and to apply it to the drying of acrylic coatings on textiles. Pt catalysts deposited on ceramic fibres (Al2O3) were employed, For propane, the diffusive catalytic burner was used. The combustion efficiency of the diffusive catalytic burner deteriorated rapidly when it was installed in a downward position. Two concepts of forced diffusion combustion and premixed combustion were introduced to improve the downward placed diffusive catalytic burner, The combustion efficiency was enhanced with these modifications, but the forced diffusion was preferred since premixed combustion raised the temperature of the catalyst above 700 degrees C leading to sintering of the catalyst. For the toluene catalytic burner the premixed combustion mode was adopted. Its optimum operation conditions were obtained by analyzing the temperatures within the catalyst layer and by adjustment of the toluene mixture. Field tests were performed on the drying acrylic coatings using the catalytic burners. The results showed that the use of catalytic burners had several benefits such as energy savings and less pollutant emissions. Copyright (C) 1999 John Wiley & Sons, Ltd
Numerical studies of catalytic combustion in a catalytically stabilized combustor
No full textThis work aims to investigate numerically the catalytic combustion of a catalytically stabilized combustor. The numerical model treated a catalytic channel deposited with Pt and used a plug model of laminar, one-dimensional, and steady-state how. The predicted conversions of mixture and ignition temperatures of surface reaction agreed well with the measured data when a multi-step mechanism was used for the CH4 surface reaction over Pt. The flame speed of a mixture supported by catalytic surface reaction was found to increase compared with a mixture without a catalytic combustion. CO mole fractions were analysed for three cases-gas reaction, surface reaction, and gas reaction coupled with surface reaction. The case of solely gas reaction produced the most CO emission and the case of solely surface reaction generated the least CO emission. The position where flame ignites was also evaluated numerically. There was only a small difference between the measured and predicted results on the starting points of flame in the catalytic channel. As a result, the plug model was shown to model surface ignition very well, however, it did not predict well the position of flame ignition. Copyright (C) 2000 John Wiley & Sons, Ltd
Perceived illumination measured
No full textWe consider a method of measurement of apparent illumination using the perceptual phenomenon of fluorescence to which we give a psychophysical explanation based on the hypothesis of direct relation of perception of self-luminosity to the apparent illumination of the scene observed by the viewer. We report results of three experimental studies: (1) measurements of apparent illumination when a fiat mondrian in the darkness is observed; (2) measurements of apparent illumination in a "rich" 3D scene; (3) testing linearity of the subjective illumination space. Based on the obtained data, we confirm the basic hypothesis of a relation between the self-luminosity phenomenon and the perceived illumination, and show that the suggested method of measurement of apparent illumination gives reliable and accurate (errors were in the range 4-10%) values of its chromatic components. Apparent illumination in the case of a mondrian observed in the darkness is found unstable, which can be expected given that the context of such a scene is insufficient for obtaining a unique solution for all the components of the photometric problem. In the second experiment, we show that the measurement results remain constant when the context of a "rich" 3D scene is changed and that they follow the changes in illumination conditions. In the third experiment, we study the composition of different illuminations and show that the simple relation f = f(1) + f(2) holds for the measurement of the illumination (f) when two other illuminations (f(1), f(2)) are applied simultaneously. (C) 1998 John Wiley & Sons, Inc.Authors thank Du Sik Park for development of the software used in the experiments; they are indebted to all the colleagues from SP Lab of SAIT who participated in the experiments; they are grateful to J. McCann, O. Orlov, V. Maximov, and A. Gilchrist for inspiring and helpful discussions. Significant improvement of the first version of the article was done by T. Schapiro and D. Petrov in Sleepy Hollow, MI, for which the authors are very thankful
Effect of interfacial tension on micellization of a polystyrene-poly(ethylene oxide) diblock copolymer in a mixed solvent system
No full textThe micellization of a polystyrene-poly(ethylene oxide) (PS-PEO) diblock copolymer in a mixed solvent of water and tetrahydrofuran (THF) was studied in terms of an aggregation number as measured by laser light scattering. The results show the aggregation number (f) of the micelle decreases monotonically as the amount of THF is increased. These experimental results are compared with a theoretical model that includes the variations in the interfacial tension. Experimentally, the interfacial tension is adjusted with the addition of relatively low levels of THF. The theory indicates that the aggregation number decreases as the interfacial tension is decreased. The theoretical prediction is in very good agreement with the experimental results. The main conclusion of this study is that the interfacial tension is the key factor in determining the aggregation number of the diblock copolymer micelle in a water-THF solvent system. (C) 2002 Elsevier Science Ltd. All rights reserved
A fast and stable method for detecting and tracking medical organs in MRI sequences
No full textA discrete dynamic model for defining contours in 2-D medical images is presented. An active contour in this objective is optimised by a dynamic programming algorithm, for which a new constraint that has fast and stable properties is introduced. The internal energy of the model depends on local behavior of the contour, while the external energy is derived from image features. The algorithm is able to rapidly detect convex and concave objects even when the image quality is poor
Experimental and numerical studies on combustion characteristics of a catalytically stabilized combustor
No full textThis study aims to investigate surface catalytic reaction and flame combustion of lean premixed mixture in a catalytically stabilized combustor through experiment and modeling. Five types of catalyst beds composed of Various combinations of noble metal catalysts, Pd and Pt, and a high temperature catalyst, La-Mn-hexaaluminate, were tested. Results showed that the most active catalyst system consisted of a Pd catalyst in the first stage of the catalyst bed and a Pt catalyst in the second stage. A numerical simulation, consisting of three sets of multi-step elementary surface reactions for CH4 oxidation over Pt, was conducted and the most accurate model was used to evaluate the catalyst bed and the homogeneous reaction. The numerical simulation showed that the flame speed of the mixture supported by catalytic surface reaction was much raised as compared to the mixture without a catalytic combustion. (C) 2000 Elsevier Science B.V. All rights reserved
Illuminant direction and shape of a bump
No full textAn algorithm for recovering illuminant direction from the image data of a smooth Lambertian surface illuminated with a distant pointwise light source is presented. The algorithm is based on analysis of intensity distributions around structural elements of the image, such as image regions corresponding to bumps. After recognition of a bump in the image and estimation of the illuminant direction, the image data are integrated in order to recover the shape of the surface patch. The shape integration algorithm, which is based on a novel theoretical approach, is used to compute the normal vector field in the bump region without use of any explicitly given initial curve or initial data about the bump region. The theoretical consideration is illustrated with some results achieved on simulated and on realistic images. (C) 1998 Optical Society of America
Home photo categorization based on photographic region templates
No full textIn this paper, we propose new photo categorization which is suitable for a home photo album. To enhance the categorization, both local and global concepts of the photos are modeled and their combined concept learning method for the photo categorization is proposed. The local and global concepts are trained by individual support vector machines. Region templates for the local concepts of generic home photos are proposed. Further, local concepts are merged with confidence to lead to the global concept to achieve reliable categorization. Experiment results show that the proposed method is useful to detect multi-category concepts for the home photo album
Automatic photo indexing based on person identity
No full textIn this paper, we propose a novel approach to automatically index digital home photos based on person identity. A person is identified by his/her face and clothes. The proposed method consists of two parts: clustering and indexing. In the clustering, a series of unlabeled photos is aligned in taken-time order, and is divided into several sub-groups by situation. The situation groups are decided by time and visual differences. In the indexing, SVMs are trained with features of pre-indexed faces to model target persons. The representative feature vector of the person group from the clustering is queried to the trained SVMs. Each SVM outputs a numeric confidence value about the query person group. The query person group is determined to the target person by the most confident SVM. The experimental results showed that the proposed method outperformed traditional person indexing method using only face feature and its performance increased to 93.56% from 72.31%
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