WEB APPLICATION FOR MEASURING OF THE COMPONENTS CONTENT WITH PHASE TRANSITION IN HETEROGENEOUS MATERIALS

The possibility of using raster images to improve the accuracy of processing differential thermal analysis (DTA) data is considered. Estimation of error in measuring of components content with a phase transition in heterogeneous materials by the DTA data presented in the form of raster images was made. Using languages HTML, CSS, JavaScript as well as Canvas technology, a web-application for processing DTA data presented as raster images was created. The application allows measuring the relative content of components with a phase transition in heterogeneous materials with an error of ±3% by scan data of peaks in DTA curves. The application created in this work can use any Internet browser as a software environment.


Problem statement and purpose of research.
Research data is often obtained in visual form. Such data can be oscillograms of signals, the results of differential thermal analysis (DTA), of microscopy, and others. To increase the accuracy of measurements based on such data, they must be digitized.
Digitization for visual information takes the form of the raster (digital) images [1]. If the instruments recording the visual information do not initially present it as a raster image, digitization can be performed by photographing the output data of these instruments with a digital camera.
The necessary information can be extracted from a raster image by the scanning and subsequent calculations based on the scan data. This requires the creation of programs for processing raster images. Significant opportunities for such processing are provided by means used in the Internet: HTML, CSS and object-oriented programming language JavaScript. HTML and CSS languages allow creating a convenient user interface in the form a web page. JavaScript language provides all necessary means for SSN 1562-9945 (Print) ISSN 2707-7977 (Online) 68 processing of raster images. Any Internet browser can be the software environment for web applications created by these languages.
In a study of the processes in materials associated with phase transitions (PT), the differential thermal analysis method [2] is widely used. The results of this method are usually obtained in visual form. The presence of endothermic and exothermic peaks in the DTA data not only identifies the phase transition in the material, but also makes it possible to obtain from these peaks information on temperature and heat of phase transition. DTA data of heterogeneous materials containing a component with a phase transition make it possible to measure the content of this component. Such measurement can be performed by comparing the peak areas for DTA curves of the calibration sample containing 100% of the material with phase transition and heterogeneous material [3]. The area of objects in raster image can be determined with high accuracy on the base of scan data [4]. This makes it possible to use DTA data, presented in the form of raster images, for measuring with high accuracy the content of components with phase transition in heterogeneous materials.
In view of the foregoing, the purpose of this work is to create by web software a program that allows using differential thermal analysis data presented in the form of raster images to measure the relative content of components with phase transition in heterogeneous materials.
Main part. As known [3], the relative content of C component with PT in heterogeneous material can be determined from DTA data as % 100 % 100 where me, mx are masses of calibration sample and tested material; Se, Sx are the peak areas associated with PT in the DTA curves of calibration sample and tested material; ke = me/Se is the calibration coefficient.
If DTA data is presented as a raster image, then after scanning along the contour of DTA peak associated with phase transition, the array of points coordinates in pixels xi, yi (1 ≤ i ≤ N) can be obtained. On the basis of this array, one can calculate the peak area by using the Gauss formula [5] as (2) In the case where the DTA data for calibration sample and tested material are recorded under the same conditions (the same heating rate and sensitivity of DTA), it is possible to determine in accordance with (1) the relative content of component with phase transition in heterogeneous material by performing the scanning of DTA peak for the tested sample and calculation the value of Sx in accordance with the formula (2). Taking into account (1) and neglecting the small error in determining the mass during analytical weighing, we can obtain the assessed value of the absolute error at determining C: ( If we do not take into account the blurriness of DTA lines, then the absolute error at scanning of the points coordinates in raster image is equal to the quantization step of 1 pixel. Therefore, when the length of contour along which the DTA peak of tested material was scanned is equal to P, we can estimate the absolute error in determining of the area ∆Sx on the basis of scan data xi, yi (1 ≤ i ≤ N) in the following way:       As it can be seen in Fig. 3, at performing the steps of ke determination, the user must introduce the mass of calibration sample me in the form field and perform a scanning along the DTA contour of the peak for this sample.
The calculation of ke occurs after pressing the "Find coefficient" button. The script serving these processing steps contains means for checking the filling of the "me =" form and performing a scan. If the form is empty or the scan is unperformed, the alert() method opens a dialog window with the corresponding message. The value of the calibration coefficient ke in units of mg/pixel 2 can be seen in window opened by alert() method after pressing the "Find coefficient" button ( Fig. 3).
When pressing the "Content" button, the transition to processing steps associated with the measurement of relative content of component with phase transition in the heterogeneous material takes place. The user must introduce the mass of the testing sample in the "mx =" form field and scan the DTA peak of this sample. When pressing the "Calculate content" button, the program performs calculations according to formulas (1) -(4) and displays the measurement results in the hidden form fields (Fig. 4). The raster images of DTA data allows measuring the relative content of component with phase transition in heterogeneous material with a relative error of about ± 3%, when processing is executed using the program described above.
Conclusions. The program for processing raster images with differential thermal analysis data was created by languages that are used for the information presenting on the Internet (HTML, CSS, JavaScript). The program is implemented as a web application that allows using the scan data of DTA peaks to measure the relative content of components with a phase transition in heterogeneous materials. The measurement accuracy is ~ ±3%. The application can use any Internet browser as a software environment.