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of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

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Author: Elena Koleva

  • TECHNOLOGICAL BASIS OF “INDUSTRY 4.0”

    EBL in the Industry 4.0 Era

    • Ivan Kostic
    • Katia Vutova
    • Elena Koleva
    • Anna Bencurova
    • Robert Andok
    Industry 4.0, Vol. 8 (2023), Issue 8, pg(s) 381-384
    • Abstract
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    In this work, electron beam lithography (EBL) is presented as an important technology shaping the future of semiconductor manufacturing within the Industry 4.0 initiative. The EBL contribution to the ongoing evolution of electronic devices and technologies is discussed in the context of the Industry 4.0 initiative. Semiconductor technologies are foundational to the implementation of Industry 4.0, playing a critical role in enabling advanced computing, communication, sensing, and control systems. They facilitate the creation of intelligent, interconnected, and automated systems in the Industry 4.0 initiative. In addition, we present some of our results in the field of EBL research. The focus is on investigating the electron beam resist profile depending on various process parameters. The influence of electron beam lithography parameters, such as electron energy, resist thickness, and exposure dose, on the resist sidewall shape (profile) is studied for the PMMA (polymethyl-methacrylate) positive electron beam resist. Simulation results based on measurements along the resist profile depth are presented and discussed. The aim of this work is to develop and validate models for predicting and precisely controlling resist profiles in thick PMMA layers applied in the fabrication of electronic devices.

  • DOMINANT TECHNOLOGIES IN “INDUSTRY 4.0”

    Binary logistic regression for defect-free electron beam welding

    • Elena Koleva
    • Asya Asenova-Robinzonova
    Industry 4.0, Vol. 8 (2023), Issue 1, pg(s) 9-11
    • Abstract
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    Using the method of binary logistic regression, the dependence of dichotomous variables on one or more, quantitative or qualitative independent variables is studied. In order to solve problems with binary dependent variables, binary choice model estimation methodologies, such as logistic regression (logit) and probit regression (probit), can be implemented. The logistic model is based on the logistic distribution, while the probit model is based on the normal distribution. In this paper the binary logistic regression methodology is applied for obtaining defect-free welds by electron beam welding process, based on experimental data.

  • MATHEMATICAL MODELLING OF TECHNOLOGICAL PROCESSES AND SYSTEMS

    Multicriterial optimization strategies for electron beam grafting of corn starch

    • Lilyana Koleva
    • Zlatina Petrova
    • Elena Koleva
    • Mirela Braşoveanu
    • Monica R. Nemţanu
    • Georgi Kolev
    Mathematical Modeling, Vol. 5 (2021), Issue 4, pg(s) 133-135
    • Abstract
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    Grafting is the most effective way of modifying and regulating the properties of natural polysaccharides for the production of highly efficient graft copolymers, which have applications as flocculating agents for the treatment of different wastewaters. An experimental investigation connected with the modification of starch by grafting acrylamide with the application of electron beam irradiat ion is performed. In this paper the implementation of different multi-criteria optimization strategies, solving the problem with the choice between several compromise Pareto-optimal solutions are presented and compared for the process of electron beam grafting of corn starch. The compromise Pareto-optimal solutions are obtained by implementation of genetic algorithm and a set of requirements for the desired reference direction (minimum or maximum) and the constraints of the investigated quality characteristics and their variances under production conditions, which ensure the fulfilment of several goals – economic efficiency, assurance of low toxicity and high copolymer efficiency in flocculation process.

  • Electron Beam Melting and Refining of Copper

    • Asya Asenova-Robinzonova
    • Lilyana Koleva
    • Elena Koleva
    • Vania Vassileva
    • Katia Vutova
    Materials Science. Non-Equilibrium Phase Transformations., Vol. 7 (2021), Issue 3, pg(s) 93-95
    • Abstract
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    Experimental results for the quality of electron beam melting and refining of pyro-refined copper samples are analysed by an empirical model estimation approach. Investigation of the influence of the process parameters – melting power and time of refining on the removal efficiency of specific impurities, overall removal efficiency and material losses is performed.

  • DOMINANT TECHNOLOGIES IN “INDUSTRY 4.0”

    Optimization of electron beam lithography processing of resist AR-N 7520

    • Elena Koleva
    • Ivan Kostic
    • Lilyana Koleva
    • Katia Vutova
    • Irina Markova
    • Anna Bencurova
    • Anna Konecnikova
    • Robert Andok
    Industry 4.0, Vol. 6 (2021), Issue 5, pg(s) 189-191
    • Abstract
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    This work presents experimental and theoretical investigation of exposed and developed negative electron resist AR-N 7520 profiles using electron beam lithography system ZBA23 (Raith) at variation of the exposure doses and pre-defined exposure pattern. Several overall geometry quality criteria for the shape of the developed resist profile cross-sections are defined. Empirical models are estimated for the dependence of overall geometry characteristics of the obtained resist profiles on the exposure dose. These overall quality characteristics are used for defining of technological requirements for the formed profiles and for obtaining optimal regimes by multicriterial optimization.

  • THEORETICAL FOUNDATIONS AND SPECIFICITY OF MATHEMATICAL MODELLING

    3D electron beam distribution estimation by neural models

    • Elena Koleva
    • Lilyana Koleva
    • Tsvetomira Tsonevska
    Mathematical Modeling, Vol. 4 (2020), Issue 3, pg(s) 79-81
    • Abstract
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    The electron beam technological processes like electron beam welding, electron beam additive technologies, etc. depend strongly on the characteristics of the electron beam, generated by the electron gun. In this work the estimation of the 3D radial current density distribution using training, testing and validation of different artificial neural networks is considered. The model estimation is based on experimental measurements of the electron beam current distribution in three cross-sections of the beam at different distances from the magnetic lens of the electron gun. The estimated neural models with different structures are compared. Graphical user interface for the evaluation of the radial electron beam distribution in any cross-sections of the beam is developed.

  • SOCIETY

    Development of remote-control smart home system

    • Georgi Kolev
    • Elena Koleva
    • Lilyana Koleva
    Science. Business. Society., Vol. 5 (2020), Issue 3, pg(s) 112-115
    • Abstract
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    The Smart Homes come rapidly into our everyday lives bringing comfort, security, help and many other benefits. The development of Information and Communication Technology and the advances in the applications based on Internet of Things emerged the appearing of more and more Smart Home solutions. The Smart Home System should implement default or custom integrated functions and intelligent self-adaptive methodology, based on the analysis of the habits, requirements and preferences of its inhabitants.
    In this paper the authors consider the development of Android and Wi-Fi based remote control Smart Home System, which integrates the analysis of the survey of the everyday habits of the people. An analysis of habits of 64 surveyed people was made. The results can be taken into account during the process of defining the default integrated functions at the stage of designing a Smart Home. The presence, absence or approaching certain location by the people are included as elements of the Smart Home System.

  • SCIENCE

    Investigation of lipstick properties using statistical methods

    • Lilyana Koleva
    • Zlatina Petrova
    • Marieta Hadzhiyankova
    • Elena Koleva
    Science. Business. Society., Vol. 5 (2020), Issue 3, pg(s) 89-91
    • Abstract
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    The rheological non-destructive oscillation testing is conducted in order to predict and quantify the samples’ properties of the commercial brand lipstick. The influence of the variation of the process parameters temperature, phase angle and strain are investigated. Regression models for the dependencies of the rheological and thermal properties (elastic modulus and shear stress) from the described process parameters are estimated, based on 681 experimental data in the temperature region from 26.9 °C to 74.7 °C.

  • TECHNOLOGIES

    Optimization of the electron beam welding of Steel 45 samples

    • Lilyana Koleva
    • Boriana Spasova
    • Elena Koleva
    • Nikoleta Ilieva
    Machines. Technologies. Materials., Vol. 14 (2020), Issue 8, pg(s) 352-355
    • Abstract
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    An experimental study of the geometrical characteristics of the cross sections of the thermally affected areas obtained by electron beam welding of carbon steel 45 is made. The thermally affected zone and the molten area of the welds from non-stainless steels corresponds to a zone where the physical-mechanical properties and the microstructure of the processed material are changed after the processing. The process parameters that were changed during the experiments are: welding speeds were 0.5, 1.0 and 1.5 cm/sec, the beam current was changed in the range of 30 – 133 mA and the focus position was changed from 72 mm above the sample surface to 62 mm below the sample surface. The accelerating beam voltage was 50 kV. The geometry of the weld in the cases of a deep penetrating electron beam and narrow thermally affected zone is investigated. Electron beam welding process parameter optimization is performed, based on the estimation of regression models. In such way the electron beam optical systems can be tested and the specific quality requirements for the welds obtained by electron beam welding can be fulfilled

Congresses and conferences

  • IX International Scientific Conference
    "High Technologies. Business. Society"
    04.-07.03.2024 - Borovets, Bulgaria
  • XXI International Congress
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    Winter session
    06.-09.03.2024 - Borovets, Bulgaria
  • XIX International Scientific Technical Conference
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    17.-19.04.2024 - Pleven, Bulgaria
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    24.-27.06.2024 - Varna, Bulgaria
  • IX International Scientific Congress
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  • IX International Scientific Conference
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    Summer session
    26.-29.06.2024 - Varna, Bulgaria
  • XII International Scientific Congress
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    26.-29.06.2024 - Varna, Bulgaria
  • XI International Scientific Conference
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    02.-05.09.2024 - Varna, Bulgaria
  • X International Scientific Conference
    "Materials Science. Non-Equilibrium Phase Transformations"
    02.-05.09.2024 - Varna, Bulgaria
  • XVII International Conference for Young Researchers
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    04.-07.09.2024 - Varna, Bulgaria
  • XXI International Congress
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    Summer session
    04.-07.09.2024 - Varna, Bulgaria
  • IX International Scientific Conference
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    09.-12.12.2024 - Borovets, Bulgaria
  • VIII International Scientific Conference on Security
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    09.-12.12.2024 - Borovets, Bulgaria
  • IX International Scientific Conference
    "Industry 4.0"
    Winter session
    11.-14.12.2024 - Borovets, Bulgaria
  • VI International Scientific Conference
    "Mathematical Modeling"
    11.-14.12.2024 - Borovets, Bulgaria

Scientific Technical Union of Mechanical Engineering "Industry-4.0"

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