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  Comparative analysis of modified semi-supervised learning algorithms on a small amount of labeled data

  (Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute", 2022) Lyubchyk, Leonid Mykhailovych; Yamkovyi, Klym Serhiyovych

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  The paper is devoted to improving semi-supervised clustering methods and comparing their accuracy and robustness. The proposed approach is based on expanding a clustering algorithm for using an available set of labels by replacing the distance function. Using the distance function considers not only spatial data but also available labels. Moreover, the proposed distance function could be adopted for working with ordinal variables as labels. An extended approach is also considered, based on a combination of unsupervised k-medoids methods, modified for using only labeled data during the medoids calculation step, supervised method of k nearest neighbor, and unsupervised k-means. The learning algorithm uses information about the nearest points and classes’ centers of mass. The results demonstrate that even a small amount of labeled data allows us to use semi-supervised learning, and proposed modifications improve accuracy and algorithm performance, which was found during experiments.

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  Тип елементу:Документ,

  Recycling of Multilayer Packaging Foils by using Diferent Organic Solvent

  (Babol Noshirvani University of Technology, 2019) Mumladze, T.; Tatariants, Maksym; Rimšaitė, A.; Yousef, Samy; Denafas, Gintaras

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  Multilayer Packaging wastes are one of the major problem in the world. About 6 billion tons of packages are generated per year in the world (in EU is about 82 million tons per year). Multilayer packaging foils are approximately 17% of all produced packaging films. Most produced multilayer film is based on different polymers, such as: polyethylene terephthalate (PET), polypropylene (PP), and polyethylene (PE) as main components, and an aluminum layer. However, because of their poor recyclability, most multi layers are usually incinerated or landfill, this is counteracting the efforts towards a circular economy. There are different recycling methods for this type of waste, but the main problem is that there is less company which recycling multilayer packaging foils. Also, it is very important that, mostly they recovering only one or two components and others are burned or landfilled. The aim of this research was to find the most suitable solvent for recycling multilayer packaging foils and recover two common components: polymer and Al foil. For the first experiment, there was chosen multilayer packaging foil’s different samples, such as: packaging for chocolate, chips, medicines and coffee. There was used several chemicals: acetic acid, acetone, dimethyl formamide, ethanol, ethyl acetate and toluene. These solvents are on the list of green chemicals and they were selected, due to their less impact on environment and human health. The recycling process and result was different for each samples and solvents, because of their individual characteristics.

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  Тип елементу:Документ,

  Feasibilities for hydrometallurgical recovery of precious metals from waste printed circuit boards in Lithuania

  (Lietuvos mokslų akademija, 2017) Žiūkaitė, Simona; Ivanauskas, Remigijus; Tatariants, Maksym; Denafas, Gintaras

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  Given the current trends in the WPCBs generation and precious metal value in the market, it can be concluded that recovery of precious metals from WPCBs is beneficial both economically and environmentally. Leaching by thiourea demonstrated the feasibility of Au, Cu, Ag and Pd recovery. Also the importance of pre-treatment was confirmed. The metal leaching rate for preliminarily cut and thermally treated WPCBs was 18–100% higher in comparison with that of untreated WPCBs. It can be explained by the removal of a protective soldermask layer, also by partial change of the mass and chemical structure of the WPCB matrix. After the thermal treatment, WPCBs become more crumble, they can decrease consumption of reagents and facilitate cutting. Also it was confirmed that the metal content in the old (age >20 years) WPCBs is significantly higher than in the currently generated WPCBs what is caused by the development of PCB production technology.

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  Тип елементу:Документ,

  Characterization of waste printed circuit boards recycled using a dissolution approach and ultrasonic treatment at low temperatures

  (RSC Publishing, 2017) Tatariants, Maksym; Yousef, Samy; Sidaraviciute, Ruta; Denafas, Gintaras; Bendikiene, Regita

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  Recently, the separation of waste printed circuit boards (WPCBs) using organic solvents has become more prevalent because it is an environmentally friendly and efficient technique. However, the relatively high temperatures (∼135 °C) used during the separation process lead to higher energy consumption, faster solvent degradation, and possibly higher emissions of toxic fumes. This work aims to develop a new approach to separate all layers of WPCBs at lower temperatures to avoid the above-mentioned drawbacks. Di-methyl formamide (DMF) was used in the present technique as an organic solvent, while ultrasonic treatment was applied in order to accelerate the breakage of the internal van der Waals bonds of brominated epoxy resin (BER), thus decreasing the separation time. The experiments were conducted on five WPCB samples with the same surface area of 100 mm2, cut from five different WPCB models. The experiments were carried out at 25 °C (used as a reference), 50 °C, and 75 °C to study the effect of heating rate on the separation time and on the concentration of the BER dissolved in DMF. Ultraviolet-visible spectroscopy, metallographic microscope, and SEM-EDS were used to examine the recovered BER and fiberglass structure as well as the main metal compositions of each sample, respectively. The results showed that separation time and concentration of BER strongly depended on the WPCB models. In addition, the dissolution process at 50 °C resulted in the concentration of BER close to 25 °C for most of the models, while the concentration was lowest at 75 °C. At the same time, the trend in separation time was exactly opposite, with 75 °C resulting in the fastest separation time and 25 °C in the slowest. This facile approach appears promising for its potential applications in WPCB recycling and could be applied on an industrial scale.

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  Тип елементу:Документ,

  Порівняльний аналіз ефективності міофасціального розслаблення та стретчингу як засобів подолання гіподинамії у студентів

  (Національний технічний університет "Харківський політехнічний інститут", 2026) Казак, Володимир Юрійович; Арабаджи, Анна Юріївна; Фоменко, Вікторія Вікторівна

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  У роботі розглянуто проблему тривалого статичного навантаження студентів під час навчання. Проведено порівняльний аналіз двох методик відновлення – міофасціального розслаблення (МФР) та статичного стретчингу. Досліджено вплив цих методів на зняття м’язової напруги в ділянці шиї, спини та нижніх кінцівок. Визначено переваги кожної з методик для самостійного застосування студентами 1-го та 3-го курсів з метою підвищення їхньої розумової працездатності та покращення фізичного самопочуття.

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