Katia Vutova

20181112-08
Construction of a preliminary educational system for file backup system using secret sharing technique
Takeshi Tanaka, Nobuharu Okamitsu, Noriyuki Yamada, Toyoharu Takemoto, Katia Vutova

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Information-Technology Promotion Agency points out Ransomware as the second-ranked damage to organizations as well as individuals in “10 Major Security Threats 2017”. Information is stored in three data files separately ...  read more

20140506-56
Preliminary Estimation of Incident Ion Energy by Using Simulation Software (PEGASUS)
Hideaki Kozai, Nobuyuki Fujimura, Mitsuhiro Noguchi, Hiroshi Toyota, Yoshito Shirai, Takeshi Tanaka, Katia Vutova

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Plasma base ion implantation (PBII) with self-ignited plasma generated by only pulsed voltages to the test specimen has been applied to the sterilization process. We found that the PBII process reduced the numbers of active ...  read more

20140506-55
Pulse Width Dependence of the Self-Ignited Plasma Using a Plasma-Based Ion Implantation
Kazuhiro Shimono, Nobuyuki Fujimura, Hiromitsu Noguchi, Hiroshi Toyota, Yoshito Shirai, Takeshi Tanaka, Katia Vutova

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Plasma based ion implantation (PBII) with high negative pulsed voltage applied to the test specimen has been applied to the sterilization process as a technique suitable for three-dimensional work pieces. We found that the ...  read more

20140506-46
Study of Electron Beam Resists: Negative Tone HSQ and Positive Tone SML300
Ivan Kostic, Anna Bencurova, Anna Konecnikova, Pavol Nemec, Adrian Ritomsky, Elena Koleva, Katia Vutova, Georgi Mladenov

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In this paper the contrast and sensitivity characteristics are investigated concerning the negative tone electron beam resist HSQ (hydrogen silsesquioxane) and the positive tone SML300 electron beam organic resist, designed ...  read more

20140506-36
Optical and Structural Investigations of WOx Thin Films Deposited by Electron Beam Evaporation Process
Katia Vutova, Vania Vassileva, Alexander Stoimenov, Elena Koleva, Tatyana Ivanova, Georgi Bodurov, Kostadinka Gesheva, Georgi Mladenov

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Thin films of tungsten oxide are obtained at different technological parameters using electron beam evaporation process. Their optical and structure properties are investigated and the relation with process parameters is discussed. ...  read more

20140506-21
Electron Beam Melting and Recycling of Nickel
Vania Vassileva, Katia Vutova, Veliko Donchev, Alexander Stoimenov, Dinesh Amalnerkar, Nagegownivari Munirathnam

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Experimental and theoretical investigations of the process parameters at electron beam melting and refining (EBMR) of nickel samples with the purpose of improving the composition of the performed ingots are presented and discussed. ...  read more

20140506-20
Economic and Conservative Numerical Scheme for Non-Stationary Heat Model for EBMR
Veliko Donchev, Katia Vutova, Tatiana Chernogorova

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Economic and conservative numerical method is proposed for discretization and numerical simulation of non-stationary heat model concerning electron beam melting and refining (EBMR) of metals. The axis-symmetric problem is ...  read more

20180708-07
Control of plasma parameters by Penning ion effect
density distribution of plasma, density of oxygen ions, food sterilization, Pegasus simulations, Penning effect

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We attempted to control the density of oxygen ions by adding argon gas and helium gas with metastable voltage to oxygen gas with ionization voltage, in order to determine the optimum combination and ratio of gases for food ...  read more

20180304-07
Trends in the development of cobalt production
Valeriya K. Kovacheva-Ninova, Georgi M. Savov, Vania Vassileva, Katia Vutova, Evgeni Petrov, Dobrin Petrov

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Cobalt, as one of the “critical” and “strategically important” metals, plays a key role in the contemporary development of the world’s industry. Cobalt has specialized applications where it is currently impossible ...  read more

20160506-53
Training students using presentations at meetings in the fields of physics, engineering and technologies
Tomomi Tanioka, Katia Vutova, Masayuki Yamauchi, Takeshi Tanaka

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Rapid globalization requires for researchers and engineers to have broad scientific knowledge, logical thinking, problem-solving ability, and expressiveness. To improve these skills and to help students advance in their practical ...  read more