http://repository.ukd.edu.ua/xmlui/handle/123456789/2074 Thu, 23 Apr 2026 17:26:42 GMT 2026-04-23T17:26:42Z http://repository.ukd.edu.ua/xmlui/handle/123456789/2079 Highly porous activated carbon derived from plant raw material as high-performance anode for aqueous sodium-ion supercapacitors Boichuk, Tetiana; Boichuk, Andrii; Vashchynskyi, Vitalii; Changarath, Mahesh Eledath; Krecmarova, Marie; Abargues, Rafael; Martínez-Pastor, Juan P.; Sanchez-Royo, Juan F. High power sodium energy generation devices, such as symmetric and hybrid supercapacitors, have great potential for cheap and green post-lithium applications. However, it is imperative to obtain porous structures with large surfaces and optimized pore size to enhance the electrode sorption property and to ensure fast electrochemical reactions. In this work, we investigated the influence of KOH carbon activation conditions on the morphology, porosity, and electrochemical parameters in aqueous sodium electrolytes. Our activated carbon had a maximum surface area of 1556 m2/g and a notably high mesopore content, this varying from 5 to 19 % of the total pore area. Electrochemical parameters are not only influenced by the total number of pores, but also by the optimal ratio of meso and micro pores. It is shown that in the case of sodium-based electrolytes, mesopores provide good electrode-electrolyte contact, and the capacity is mainly provided by micropores. High operating values of activated carbon in sodium aqueous electrolytes (specific capacity about 78 F/g, energy density 11 W*h/kg and power density 470 W/kg) indicates that the optimal electrode materials for a high-power device are activated carbon with a high content of mesopores obtained by the ratio of C and KOH as 1:4. Tetiana Boichuk , Andrii Boichuk , Vitalii Vashchynskyi , Mahesh Eledath Changarath , Marie Kreˇcmarov´a, Rafael Abargues, Juan P. Martínez-Pastor , Juan F. Sanchez-Royo. Highly porous activated carbon derived from plant raw material as high-performance anode for aqueous sodium-ion supercapacitors // Journal of Power Sources, 2024. Vol 622. Article 235356. Pp. 1-9: Fig.7, table 1. Mon, 01 Jan 2024 00:00:00 GMT http://repository.ukd.edu.ua/xmlui/handle/123456789/2079 2024-01-01T00:00:00Z http://repository.ukd.edu.ua/xmlui/handle/123456789/2078 Використання машинного навчання при вивченні еволюції космічних тіл та їх систем Бойчук, Андрій Михайлович; Бойчук, Тетяна Ярославівна Бойчук А. М., Бойчук Т. Я. Використання машинного навчання при вивченні еволюції космічних тіл та їх систем // Концептуальні проблеми розвитку сучасної гуманітарної та прикладної науки: матеріали VI Міжнародного науково-практичного симпозіуму (м. Івано-Франківськ, 20 травня 2022 року). Івано-Франківськ: Редакційно-видавничий відділ Університету Короля Данила, 2022. С. 36-38. Fri, 20 May 2022 00:00:00 GMT http://repository.ukd.edu.ua/xmlui/handle/123456789/2078 2022-05-20T00:00:00Z http://repository.ukd.edu.ua/xmlui/handle/123456789/2077 Аналіз стану ІТ ринку України Стисло, Тарас Романович; Ващишак, Сергій Петрович; Бойчук, Андрій Михайлович; Стисло, Оксана Василівна; Доценко, Ярослав Іванович У роботі проаналізовано основні моделі підготовки персоналу і на основі аналізу було запропоновано до впровадження оновлену модель підготовки персоналу основану на результатах співбесіди та критеріях бажаної вакансії. Today, the global IT community is experiencing significant growth in digital production and software. Nearly 30 million software developers from around the world are working to meet the digital needs of the population. And this number is constantly growing. Many factors have led to an increase in digital production all over the world, namely: the transition of most trading platforms to online commerce, the introduction of online services in most countries, the digitalization of public services, the rapid growth and promotion of technologies related to the circulation and implementation of cryptocurrencies and block-chain, the rapid growth of digital technology in the medical field and much more. It is important to note that the growth of Ukrainian IT is significantly exceeding the global figure in terms of growth and has reached 26 percent since the beginning of this year. Given the rapid change in technology and market segmentation in accordance with the practical skills of certain technologies, universities often can’t adapt themselves to current market needs and train a sufficient number of specialists. The number of trained specialists is positively affected by internal courses being offered by leading Ukrainian and global companies. Often such programs are designed to train professionals who just begin their careers in the field, and for university graduates who lack practical experience in projects. Such programs are more concerned with preparation of specialists at the Trainee and Junior level, which is certainly important, but the main shortage of staff is being observed in the segment of specialists at the middle and higher level. Given the peculiarities of the domestic information technology market, it is sometimes difficult to find a specialist in accordance with the requirements of a vacancy, as the specifics of each company, technology and requirements for specialists are significantly different. At the present stage there is an actual issue of training of a potential candidate for the position by the employer and employee of his company at the Middle level and above. Стисло Т. Р., Ващишак С. П., Бойчук А. М., Стисло О. В., Доценко Я. І. Аналіз стану ІТ ринку України=Analysis of the state og the Ukrainian it market // Вісник Хмельницького національного університету. Технічні науки, 2022. №1(305). С. 43-49: табл.1, рис.7. Sat, 01 Jan 2022 00:00:00 GMT http://repository.ukd.edu.ua/xmlui/handle/123456789/2077 2022-01-01T00:00:00Z http://repository.ukd.edu.ua/xmlui/handle/123456789/2076 Направлена антена для контролю бездротових мереж передавання даних діапазону 5 ГГЦ Ващишак, Сергій Петрович; Бойчук, Андрій Михайлович; Стисло, Тарас Романович; Мельничук, Степан Іванович; Мануляк, Ірина Зіновіївна В роботі наведено результати конструювання та досліджень активної конічної рупорної антени для роботи в діапазоні 5 ГГц, яка має здатність працювати у важких польових умовах з високим коефіцієнтом підсилення та низьким рівнем власних шумів. Recently, there has been an intensive development of wireless data networks in the 2.4 and 5 GHz ranges, or Wi-Fi. The popularity of these networks is mainly due to the transmission of multimedia information. Existing standards and data protocols for these networks ensure their smooth and high-performance operation in «ideal conditions». In fact, in cities and densely populated centers with a significant amount of such equipment as well as lack of backup channels, there is radio frequency interference. These interferences are caused by the impact of one piece of equipment on another when it is impossible to adjust by switching to backup channels. Due to the interference, the data transmission speed is reduced, and in some complex cases, the data transmission is stopped completely. This negative phenomenon especially affects the 5 GHz range, in which the signal range is less than that for the 2 GHz range. To assess the quality of wireless data transmission networks, the following characteristics are monitored: the average emission frequency and the emission bandwidth. When these characteristics go beyond the standard values, there are interferences detected by the radio frequency monitoring bodies. Monitoring is carried out monthly throughout the year by specialized measuring systems, which include spectrum analyzers and antennas. Existing antennas have the following disadvantages: instability of the amplification gain, significant noise radiation, low reliability of pushbutton switches and significant weight. To eliminate these shortcomings, the design of an active antenna with a conical horn, which has the ability to change the parameters of the antenna within the entire range of 5 GHz. The optimal parameters of the horn are calculated as well. To obtain high values of the amplification gain of the horn antenna and maintain them with high stability at temperatures from -20 to +45оС used a signal amplification unit on a high-frequency operational amplifier SZA5044Z with a thermostat on a powerful transistor. Additional stability of the electrical characteristics of the amplifier is provided by double stabilization of the supply voltage. Electronic antenna control increases the reliability of the antenna by using electronic switching instead of push-button. Electronic control also protects the antenna amplifier from overheating, changing the polarity of the battery and electromagnetic interference. Laboratory and field studies of the directional horn antenna showed high stability of its parameters, reliability and ergonomics. Additional stability of the electrical characteristics of the amplifier is provided by double stabilization of the supply voltage. Electronic antenna control increases the reliability of the antenna by using electronic switching instead of push-button one. Electronic control also protects the antenna amplifier from overheating, change of the battery polarity and electromagnetic interference. Laboratory and field studies of the beam horn antenna showed high stability of its parameters, reliability and ergonomics. Ващишак С. П. , Бойчук А. М. , Стисло Т. Р., Мельничук С. І. , Мануляк І. З. Направлена антена для контролю бездротових мереж передавання даних діапазону 5 ГГЦ=Beam antenna for controlling wireless 5 GHZ data transmission networks // Вісник Хмельницького національного університету. Технічні науки, 2021. № 5(301). С. 119-126: табл.3, рис.7. Fri, 01 Jan 2021 00:00:00 GMT http://repository.ukd.edu.ua/xmlui/handle/123456789/2076 2021-01-01T00:00:00Z