Andrzej Kotyra

Optical fiber system for combustion quality analysis in power boilers

The introduction of low emission techniques of combustion caused side-effects like oxygen lean corrosion. It also enforced more precise management of technological air, better coal milling and application of devices for combustion process monitoring. In the article authors presented their own solution of optical fiber system for combustion quality evaluation, already operating on power boiler type OP-650. Its functionality was described together with selected results of measurements. Directions of further development of the system were also indicated.

Combustion diagnosis by image processing

The paper presents the way that colour can serve solving the problem of calibration points indexing in a camera geometrical calibration process. We propose a technique in which indexes of calibration points in a black-and-white chessboard are represented as sets of colour regions in the neighbourhood of calibration points. We provide some general rules for designing a colour calibration chessboard and provide a method of calibration image analysis. We show that this approach leads to obtaining better results than in the case of widely used methods employing information about already indexed points to compute indexes. We also report constraints concerning the technique. Nowadays we are witnessing an increasing need for camera geometrical calibration systems. They are vital for such applications as 3D modelling, 3D reconstruction, assembly control systems, etc. Wherever possible, calibration objects placed in the scene are used in a camera geometrical calibration process. This approach significantly increases accuracy of calibration results and makes the calibration data extraction process easier and universal. There are many geometrical camera calibration techniques for a known calibration scene [1]. A great number of them use as an input calibration points which are localised and indexed in the scene. In this paper we propose the technique of calibration points indexing which uses a colour chessboard. The presented technique was developed by solving problems we encountered during experiments with our earlier methods of camera calibration scene analysis [2]-[3]. In particular, the proposed technique increases the number of indexed points points in case of local lack of calibration points detection. At the beginning of the paper we present a way of designing a chessboard pattern. Then we describe a calibration point indexing method, and finally we show experimental results. A black-and-white chessboard is widely used in order to obtain sub-pixel accuracy of calibration points localisation [1]. Calibration points are defined as corners of chessboard squares. Assuming the availability of rough localisation of these points, the points can be indexed. Noting that differences in distances between neighbouring points in calibration scene images differ slightly, one of the local searching methods can be employed (e.g. [2]). Methods of this type search for a calibration point to be indexed, using a window of a certain size. The position of the window is determined by a vector representing the distance between two previously indexed points in the same row or column. However, experiments show that this approach has its disadvantages, as described below. * E-mail: A.Nowakowski@ire.pw.edu.pl Firstly, there is a danger of omitting some points during indexing in case of local lack of calibration points detection in a neighbourhood (e.g. caused by the presence of non-homogeneous light in the calibration scene). A particularly unfavourable situation is when the local lack of detection effects in the appearance of separated regions of detected calibration points. It is worth saying that such situations are likely to happen for calibration points situated near image borders. Such points are very important for the analysis of optical nonlinearities, and a lack of them can significantly influence the accuracy of distortion modelling. Secondly, such methods may give wrong results in the case of optical distortion with strong nonlinearities when getting information about the neighbouring index is not an easy task. Beside this, the methods are very sensitive to a single false localisation of a calibration point. Such a single false localisation can even result in false indexing of a big set of calibration points. To avoid the above-mentioned problems, we propose using a black-and-white chessboard which contains the coded index of a calibration point in the form of colour squares situated in the nearest neighbourhood of each point. The index of a certain calibration point is determined by colours of four nearest neighbouring squares (Fig.1). An order of squares in such foursome is important. Because the size of a colour square is determined only by the possibility of correct colour detection, the size of a colour square can be smaller than the size of a black or white square. The larger size of a black or white square is determined by the requirements of the exact localisation step which follows the indexing of calibration points [3]. In this step, edge information is extracted from a blackand-white chessboard. This edge information needs larger Artur Nowakowski, Wladyslaw Skarbek Institute of Radioelectronics, Warsaw University of Technology, Nowowiejska 15/19, 00-665 Warszawa, A.Nowakowski@ire.pw.edu.pl Received February 10, 2009; accepted March 27, 2009; published March 31, 2009 http://www.photonics.pl/PLP

Application of flame monitoring system for flame spectrum analysis in industrial conditions

The flame monitoring system is intended to use in industrial condition for controlling pulverized coal combustion in power boiler. Placing the fiber-optic probes close to the each burner, one can obtain detailed information of the coal combustion process within the single burner. In order to enhance flame-monitoring system sensitivity for detection of fuels composition changes, we have measured flame emission spectra.

Analysis of two dimensional signals via curvelet transform

This paper describes an application of curvelet transform analysis problem of interferometric images. Comparing to two-dimensional wavelet transform, curvelet transform has higher time-frequency resolution. This article includes numerical experiments, which were executed on random interferometric image. In the result of nonlinear approximations, curvelet transform obtains matrix with smaller number of coefficients than is guaranteed by wavelet transform. Additionally, denoising simulations show that curvelet could be a very good tool to remove noise from images.

The fiber optic system detecting the type of burned fuel in power boilers

We present the method of detection the kind of burned fuel in industrial conditions. Wavelet transforms were applied for the signals corresponding to pulsation of chosen flame zone.

The methods of choosing the proper wavelet for analyzing the signals of the flame monitoring system

There no existing universal method of choosing a proper wavelet basis. In this article we present a methodology of choosing the adequate wavelet in detecting some of signals’ features which points to the change of the power burner working point.

Optimization of optical fiber probe for flame monitoring by application of finite element method

In the work we describe the process of design of fibre-optic probe for the flame monitoring system by method of finite elements. Probe made according to the design has successfully passed tests made in industrial boiler 0P650.

Analysis of the operation of an electro-optical Pockels effect sensor

In this paper we describe an electrooptical sensor employing the Pockels effect. We also provide its analysis in order to determine its optical transmission as a function of the voltage applied and the influence of different temperatures on its parameters. Simulation results and the error analysis from the operation of a sensor made of a BSO (Bi12SiO20) crystal have also been demonstrated.

Evanescent field absorption sensor

In this paper we present the analysis, design, and construction of a fiber optic evanescent field sensor. A standard PCS multimode fiber was used in a measurement method called the attenuated total reflection. We present sample measurements taken for an alcohol solution of cobalt chloride CoCl2(DOT)6H2O compared with the results obtained by methods of classical spectrophotometry. The sensor described can be used in the analysis of strongly absorptive substances, especially where the traditional- optical transmission-measurement methods are impossible.

Application of flame image series analysis in estimation of biomass and coal combustion operating point

The paper considers access of combustion process of pulverized coal and biomass blend using analysis of flame images. Several flame image parameters were examined as pointers of one of the basic combustion process input parameters as air and fuel flow rate. Image parameters like greyscale area region, coordinates of centre of gravity and flame area contour length were averaged in a fixed time span. The aim of investigations was assessing ability to determine air and fuel flow rates on the basis of the mentioned image parameters. Streszczenie. W artykule ocenę procesu współspalania biomasy i węgla z wykorzystaniem przetwarzania obrazu. Rozpatrywano kilka parametrów obrazu jako wskaźniki najważniejszych parametrów wejściowych procesu spalania jak wydatki paliwa i powietrza. Parametry obrazu, jak powierzchnia obszaru w skali szarości, współrzędne środka ciężkości i długość konturu były uśredniane w ustalonym oknie czasowym. Celem badań była ocena możliwości określenia wydatków paliwa i powietrza na podstawie wspomnianych parametrów obrazu (Wykorzystanie analizy sekwencji obrazów do estymacji punktu pracy procesu współspalania biomasy z węglem).