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Computer Administering of the Psychological Investigations: Set-Relational Representation

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Open Journal of Applied Sciences 2012年第2期2卷 110-114页

作者： Krasimir Yordzhev Ivelina Peneva Department of Psychology Faculty of Philosophy South-West University Blagoevgrad Bulgaria Faculty of Mathematics and Natural Sciences South-West University Blagoevgrad Bulgaria

Computer administering of a psychological investigation is the computer representation of the entire procedure of psychological assessments—test construction, test implementation, results evaluation, storage and maintenance of the developed database, its statistical processing, analysis and interpretation. A mathematical description of psychological assessment with the aid of personality tests is discussed in this article. The set theory and the relational algebra are used in this description. A relational model of data, needed to design a computer system for automation of certain psychological assessments is given. Some finite sets and relation on them, which are necessary for creating a personality psychological test, are described. The described model could be used to develop real software for computer administering of any psychological test and there is full automation of the whole process: test construction, test implementation, result evaluation, storage of the developed database, statistical implementation, analysis and interpretation. A software project for computer administering personality psychological tests is suggested.

关键词： Computer Administering Computer Testing Computer Psycho Diagnostic Mathematical Modeling Set Theory Relational Algebra Databases

Structure of Flavones and Flavonols. Part II: Role of Position on the O-H Bond Dissociation Enthalpy

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Computational Chemistry 2014年第1期2卷 1-5页

作者： Maria Hr. Vakarelska-Popovska Zhivko As. Velkov Department of Chemistry South-West University “NeofitRilski” Blagoevgrad Bulgaria.

The enthalpies of bond dissociations of the hydroxyl groups, the energy of the highest occupied molecular orbitals and the corresponding radicals spin densities of all possible ten isomeric mono-hydroxyl flavones are calculated by means of 3-parameter Becke, Lee, Yang and Parr functional. The structural factors affecting these descriptors of radical-scavenging activity are outlined. The results obtained show that the hydroxyl groups in ring A and C are more involved in the process of a radical-capturing than recently believed.

关键词： DFT BDE EHOMO Maximum Spin Density Flavones Flavonols

An Entertaining Example of Using the Concepts of Context-Free Grammar and Pushdown Automation

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Open Journal of Discrete Mathematics 2012年第3期2卷 105-108页

作者： Krasimir Yordzhev Faculty of Mathematics and Natural Sciences South-West University Blagoevgrad Bulgaria

A formal-linguistic approach for solving an entertaining task is offered in this paper. The well-known task of the Hanoi towers is discussed in relation to some concepts of formal languages and grammars. A context-free grammar which generates an algorithm for solving this task is described. A deterministic pushdown automation which in its work imitates the work of monks in solving the task of the Hanoi towers is built.

关键词： Context-Free Grammar Context-Free Language Pushdown Automation Hanoi towers Discrete Mathematics Learning

Improving Performance of Computer Algebra Systems

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Journal of Software Engineering and Applications 2023年第10期16卷 521-529页

作者： Kostas Zotos Irena Atanassova Department of Informatics Faculty of Science and Mathematics South-West University “NeofitRilski” Blagoevgrad Bulgaria

Computer Algebra Systems have been extensively used in higher education. The reasons are many e.g., visualize mathematical problems, correlate real-world problems on a conceptual level, are flexible, simple to use, accessible from anywhere, etc. However, there is still room for improvement. Computer algebra system (CAS) optimization is the set of best practices and techniques to keep the CAS running optimally. Best practices are related to how to carry out a mathematical task or configure your system. In this paper, we are going to examine these techniques. The documentation sheets of CASs are the source of data that we used to compare them and examine their characteristics. The research results reveal that there are many tips that we can follow to accelerate performance.

关键词： Mathematical Software Computer Algebra Systems CAS Improving Performance CAS Performance CAS Optimization MATLAB Maple Mathematica

Advantages & Disadvantages of Online CAS

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Journal of Software Engineering and Applications 2023年第9期16卷 496-504页

作者： Kostas Zotos Irena Atanassova Department of Informatics Faculty of Science and Mathematics South-West University “Neofit Rilski” Blagoevgrad Bulgaria

Online Computer Algebra Systems (CAS) have become increasingly popular among students and teachers. The reasons are many such as being more flexible, simple to use, accessible from anywhere, etc. However, as with any educational tool, they also have some disadvantages that we should know. The purpose of this study is to analyze advantages and disadvantages of online CASs and propose some techniques to optimize CAS performance in order to reduce weaknesses. The research results reveal that online CAS versions are on the rise but lag in some capabilities in comparison with desktop versions.

关键词： Mathematical Software Online CAS Computer Algebra Systems Advantages of Online CAS CAS

Secret Sharing Based on the Residue Theorem

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通讯和计算机（中英文版） 2012年第2期9卷 148-154页

作者： Boncho Ivanov Alexandrova Nina Vasileva Sinyagina Petko Vasilev Kochevski Department of Applied lnformatics Technical University of Gabrovo Gabrovo 5300 Bulgaria Department of Computer Science South-West University Blagoevgrad 2700 Bulgaria

Which Geopolitics for the European Union？ The EU＇s Eastern Partnership

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International Relations and Diplomacy 2015年第7期3卷 480-486页

作者： Jean F. Crombois American university in Bulgaria Blagoevgrad Bulgaria

This article discusses whether the European Union （EU） has engaged in a geopolitical approach when it comes to its Eastern neighbors, now included in the EU＇s Eastern Partnership. The paper concludes that the EU has not engaged in a geopolitical approach when it comes to its policies towards its Eastern neighbors. Instead, it has approached them through the prisms of inter-connectedness and interdependency. The main reason for that rejection of geopolitical approach lies in the role that the EU has assigned to itself as an international actor, i.e. as a civilian and normative power. Finally, the use of civilian instruments would avoid the EU falling into a geopolitical trap that would lead to a zero sum game situation for its Eastern neighours in their relationships with Russia.

关键词： European Union geo-politics Eastern Partnership

Recent behavior and possible future evolution of the glacieret in the cirque Golemiya Kazan in the Pirin Mountains under conditions of climate warming

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Journal of Mountain Science 2019年第1期16卷 16-29页

作者： Peter NOJAROV Emil GACHEV Karsten GRUNEWALD National Institute of Geophysics Geodesy and Geography Bulgarian Academy of Sciences south-west university "Neofit Rilski" Leibniz Institute of Ecological Urban and Regional Development

This research reveals relationships between climate variables and inter-annual dynamics in the area of the glacieret located in the cirque Golemiya Kazan in the Pirin Mountains. The study period is 1993–2017. The correlations are identified using statistical methods. Also, a statistical model is constructed, including some climate variables as predictors. Despite the evident decrease of the glacieret's size in the period from the 1950 s onwards, the long-term trends for the last decades have been insignificant. The main climatic factors influencing the inter-annual dynamics in the area of the glacieret are air temperature, precipitation, zonal and meridional winds and relative humidity. With respect to the dynamics in the area of the glacieret, the important trends in the different climate variables are those of the warm period air temperatures and zonal(u) wind. They also determine to a great extent its future development by acting in two opposite directions – rising temperatures in the warm period will lead to a rapid decrease of its area by the end of the melting season, while the change of wind directionfrom west to east in the warm period will increase its area. The influence of the zonal wind in the warm period is explained mainly by the location of the glacieret in the cirque. Generally, the glacieret is tilted downwards from west to east. Thus, westerly winds facilitate blowing away the snow from the surface of the glacieret, assisting its melting in the warm period. Easterly winds do not have such an effect. The combination of the opposite effects of these two most important climate variables leads to the most likely scenario for the future development of the glacieret, according to which by the middle of this century it is expected to turn into a semi-permanent snow patch, which disappears after some summers, and by the end of the century to completely melt every year before the end of the melting season.

关键词： Climate warming Glacieret Pirin Mountains Statistical modeling Glacieret area Projection

Natural Rubber Based Composites Comprising Different Types of Carbon-Silica Hybrid Fillers. Comparative Study on Their Electric, Dielectric and Microwave Properties, and Possible Applications

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Materials Sciences and Applications 2016年第6期7卷 295-306页

作者： Ahmed A. Al-Ghamdi Omar A. Al-Hartomy Falleh R. Al-Solamy Nikolay Dishovsky Mihail Mihaylov Petrunka Malinova Nikolay Atanasov Department of Physics Faculty of Science King Abdulaziz University Jeddah KSA Department of Mathematics Faculty of Science King Abdulaziz University Jeddah KSA Department of Polymer Engineering University of Chemical Technology and Metallurgy Sofia Bulgaria Department of Telecommunications University of Telecommunications and Post Sofia Bulgaria Department of Communication and Computer Engineering South-West University "Neofit Rilski" of Blagoevgrad Blagoevgrad Bulgaria

The paper presents a comparative study on the electric, dielectric and microwave properties of natural rubber based composites comprising dual phase fillers prepared from furnace carbon black or conductive carbon black with a different amount of silica. It has been established that, the specifics of the carbon phase have a marked strong effect upon the properties mentioned above. The interpenetration of the two filler phases and the grade of isolation of the conductive carbon phase by the dielectric one depend on the ratio between them. On the other hand, that leads to a change in all properties of the studied composites, which allows tailoring those characteristics.

关键词： Polymer Composites Hybrid Fillers Dielectric Properties Microwave Properties