Browsing by Author "Bubela, Tetiana"

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Bit operations with elements of the RSA algorithm in encryption-decryption of color images
(Видавництво Львівської політехніки, 2022-02-28) Kovalchuk, Anatoliy; Peleckh, Yuriy; Bubela, Tetiana; Lviv Polytechnic National University
An image as a stochastic signal is one of the most common forms of information. Protecting images from unauthorized access and applying is a correspondingly urgent task. This causes the use of well-known classical encryption methods in the case of image encryption. But the image is a signal that possesses, in addition to typical informativeness, also visual informativeness. Informativeness for modern image processing methods makes it possible to ensure unauthorized access. Creating an attack on an encrypted image is possible in two ways: by traditional hacking of encryption methods, or by classical methods of visual image processing (filtering, highlighting contours, etc.). In this regard, one more requirement is put forward to encryption methods in the case of their application concerning images – this is the complete noise of the encrypted image. This is necessary so that the use of visual image processing methods becomes impossible. The RSA algorithm is one of the most widely known industrial standards for encrypting signals. Unlike symmetric encryption, in an open-key encryption scheme, it is impossible to calculate the decryption procedure, knowing the encryption procedure. Namely, the working time of the algorithm for calculating the decryption procedure is so great that it cannot be implemented on any modern computers, as well as on computers of the future. Such coding schemes are called asymmetric. Therefore, the urgent task is to implement the application of the RSA algorithm so that when encrypting an image: – the cryptographic stability of the RSA algorithm has not become worse; – the full image noise was achieved to prevent the use of visual image processing techniques. The algorithm of elements of the RSA algorithm, as the most resistant to unauthorized decryption of signals, and bitwise operations for a compatible combination during encryption and decryption of images is proposed by the authors. Encryption – decryption is performed without additional noise. The proposed algorithm is applied to images in which there are strictly extracted contours. Elements of the RSA algorithm are assigned to perform bitwise operations on the intensity values of pixels of a color image. The developed algorithm has higher cryptographic stability compared to the traditional RSA algorithm. The authors described the possibilities of using elements of the RSA algorithm in bitwise transformations when encrypting and decrypting images. The results of encryption simulation for cryptographic transformations of color images of a given dimension are presented. Modified models and algorithmic procedures of key formation processes of direct and inverse cryptographic transformations have been developed. They are reduced to elemental mathematical operations.
Characteristic express checking of admittance measurement units for cyber-physical systems
(Publishing House of Lviv Polytechnic National University, 2016) Yatsuk, Vasyl; Pokhodylo, Yevhen; Bubela, Tetiana; Yatsuk, Yurii; Lviv Polytechnic National University
Measurement of RLC-parameters of objects non-electric nature (for example, biological, agricultural, environmental, etc.) with high metrological characteristics is an essential element for building a cyber-physical systems analytical purposes. The reliability of the measurement results of the equipment can be provided only by periodic metrological control over the exploitation conditions. Traditionally analytical RLC-meters are calibrated by means of standard samples and it leads to significant problems in their metrological assurance and complicates whole procedure. It is suggested to make operating check of admittance measurement units metrological characteristics by use of intelligent devices based on code-controlled measures. Critical analysis of available approaches for measures creation was carried out and an admittance codecontrolled measure scheme based on active simulators was designed. The mathematic model for measuring transfer function, analytical devices calibration process and advantages of the operating check based code-controlled measure was presented too.
Means of measurement of relative quality indicators by immittance parameter
(Видавництво Львівської політехніки, 2005-02-24) Pokhodylo, Yevgen; Yatsuk, Vasyl; Bubela, Tetiana; Lviv Polytechnic National University
The paper describes the problems of implementation of the differential method of product quality assessment using the immittance method. The differential method of quality control is realized through a comparison of parameters of the immittance of the controlled and reference samples. The application of traditional meters of CLR-parameters complicates the process of the differential method implementation. Such units cannot directly measure relative quality. Virtually all models of such measuring instruments measure only the parameters of the monitored object through the input device. Thus, they are not adapted to the direct measurement of relative quality indicators. The authors propose to introduce a product pattern with the values of the code-controlled measure of admittance. These values are obtained by measuring the parameters of a standard pattern of products of a given quality level with a traditional immittance meter. The structure of the measuring instrument for the direct measurement of the relative quality index is given. The method is realized by comparing the parameters of the controlled object and the electrical standard pattern in the form of a code-controlled measure of admittance. This allows building quality control means for any nonelectrical products. Controlled products are supplied by electrical parameters of immittance with means of capacitive primary converters. Direct application of the differential method of quality assessment allows simplifying the measuring instrument as much as possible and reduce the time of product quality assessment. The proposed structure of the unit enables us to determine the deviation of the relative indicator from the value one. According to the obtained value of the indicator, products can be quickly classified by quality levels.
Preconditions for the creation of a meat freshness control and identification system
(Видавництво Львівської політехніки, 2023-02-28) Bubela, Tetiana; Bohush, Bohdan; Lviv Polytechnic National University
The relevance of creating a comprehensive system for meat control and identification to determine its freshness level has been demonstrated in the study. The drawbacks of traditional organoleptic and laboratory methods commonly used for meat inspection were analyzed. The authors presented the advantages and challenges of employing an electronic nose. A design for a meat control and identification system was proposed, which includes an Arduino Uno microcontroller, Raspberry Pi, USB to TTL adapter, gas sensors, color sensor, thermal camera, and image sensor. The proposed implementation of the electronic nose system on a single-board computer demonstrates its success in controlling and identifying meat freshness. A matrix of semiconductor gas sensors, TGS2602, MQ137, and MQ138, is formed as olfactory sensors, and TCS3200 is used as an RGB vision sensor, enabling the identification of the smell and color of different degrees of meat freshness. To obtain clear output differences from the gas sensors that react to the freshness level of meat, the baseline method is proposed for use. Therefore, a system enhanced with neural network capabilities will replace traditional devices for identifying meat freshness.
Термоелектричне матеріалознавство і нанотехнології. Практика та теорія
(Видавництво Львівської політехніки, 2019-02-28) Стадник, Б.; Яцишин, С.; Луцик, Я.; Бубела, Т.; Фрьоліх, Т.; Stadnik, Bohdan; Yatsyshyn, Svyatoslav; Lutsyk, Yaroslav; Bubela, Tetiana; Frohlich, T.; Національний університет “Львівська політехніка”; Технічний університет м. Ільменау; Lviv Polytechnic National University; Technical University of Ilmenau
Прогрес у галузі термоелектрики вимагає подальшого розвитку матеріалознавства углиб речовини завдяки використанню прикладних і теоретичних здобутків нанотехнологій, зокрема нанотермодинаміки. Це дає змогу розширити спектр чинних термодинамічних сил з урахуванням сил, притаманних наноструктурованим речовинам, та підвищити ефективність залучення концепції вихрових термоелектричних струмів для точнішого вимірювання температури термоелектричними сенсорами. Проведені дослідження матеріалів термоелектричних сенсорів охоплюють не лише вивчення стабільності термо-ЕРС, але й вивчення їх методами неруйнівного акустичного контролю. Це дає змогу оцінити й розвинути роль специфічних механізмів формування вихрових термоелектричних струмів у дрейфі термо-ЕРС.