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Hristo Hristov

University of Plovdiv, Software Technology, Faculty Member

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Hristo Hristov received PhD from University of Plovdiv “Paisii Hilendarski”. He is currently working as an Associate professor at the Department of Computer Technology, Faculty of Mathematics and Informatics, Plovdiv University, Bulgaria. His research areas include Web Design and Development, Web Accessibility, Computer Networks, eLearning tools and environments, Methodology of Teaching Computer Science and others.

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Bulgarian Academy of Sciences

Todorka Terzieva

Maíra Rejane Marques Samary

Universidad de Chile

Alexander R Jensenius

University of Oslo

Rebecca Reynolds

Rutgers, The State University of New Jersey

Тодорка Глушкова

University of Plovdiv

Todorka Glushkova

University of Plovdiv

ВЕНЕТА ТАБАКОВА-КОМСАЛОВА

Katja Fleischmann

Griffith University

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Papers by Hristo Hristov

Teaching of Web Design and Programming as a Role-Playing Team Building Game

International Journal of Information and Education Technology, 2023

The paper examines a form of training whose aim is to teach technologies for designing and stylin... more The paper examines a form of training whose aim is to teach technologies for designing and styling responsive web page views and implementing web site events by students in an academic environment. In this form of training a role-play, taken by the practice of a software company is simulated. Data collection and evaluation of the results was carried out through qualitative methods of participant observation, survey, interview, and quantitative comparative analysis. The article analyzes in details the role-playing games, training content, stages of implementation and other aspects of the organization of experimental form of training in Web Design and Web Programming. Teaching, as a simulated role-playing game, is performed during six school hours, in two consecutive weeks and consists of four stages. In the role play, students apply knowledge and teamwork skills in HTML, CSS, JavaScript, jQuery etc. Each team is made up of five students with roles of manager, web designer, graphics designer, web stylist and web developer. The teams' organization is based on work products adaptation of the Rational Unified Process Methodology. The end product of the role-playing game is the development of a website by the team, while its final result for the learning process is the knowledge and skills acquired during formal training by the teacher, and the informal training that took place between the students during their teamwork.

A MODEL-BASED APPROACH TO ENHANCING WEB ACCESSIBILITY FOR INDIVIDUALS WITH SPECIAL EDUCATION NEEDs

International Journal on Information Technologies & Security, 2023

An important aspect in software development nowadays is digital opportunities for meeting the nee... more An important aspect in software development nowadays is digital opportunities for meeting the needs of disadvantaged affected people with Special Education Needs (SEN). In this article, we consider the problem of identifying and improving the accessibility of web platforms designed for users who have SEN. To achieve this goal, a model was created and implemented in the web platform sopbg.org. The specialized website, which is maintained and developed by the authors of the publication, unites a community of several thousand users with SEN. The intensive consumption of the platform provided the authors with the opportunity to make a number of improvements to the applied model, some of which should be considered.

Generations of human-computer interactions: evolution, tendencies and perspectives

Journal of Physics: Conference Series

In this paper, we present the usability evolution of human-computer interactions. In addition, we... more In this paper, we present the usability evolution of human-computer interactions. In addition, we group the various user interfaces of human-computer interaction into two generations with three classes each. The most user interfaces for human-computer interaction are assigned into a class depending on objective criteria scores, such as technical literacy level, level of natural interactions, user learning curve and UI’s ability to adapt. In addition, current tendencies for HCI are presented and future perspectives are discussed. Finally, we summarize the achieved results and draw conclusions.

An Approach to Validating the Accessibility of Dynamic Web Pages.

by Hristo Hristov and Stilian Minchev

Hr. Hristov, G. Stoitsov, M. Bliznakov, S. Minchev. (2023). An Approach to Validating theAccessibility of Dynamic Web Pages.TEM Journal, 12(1),233-240., https://www.temjournal.com/content/121/TEMJournalFebruary2023_233_240.pdf, 2023

The purpose of the publication is to present a web page validation approach that is part of a met... more The purpose of the publication is to present a web page validation approach that is part of a method for designing accessible web content. The validation approach is built on standards, principles, guidelines, success criteria and techniques for web content validation. The main standards to which the approach adheres are Web Content Accessibility Guidelines and Technical Specifications for Accessible Rich Internet Applications. The publication discusses the understanding of dynamic web content, dynamic web content design and implementation method and web content validation approach.

A Model for Designing Accessible Color and Contrast for Users with Visual Deficiency and Color Blindness

H. Hristov, T. Glushkova, S. Cheresharov and M. Stoeva, "A Model for Designing Accessible Color and Contrast for Users with Visual Deficiency and Color Blindness," 2022 IEEE 11th International Conference on Intelligent Systems (IS), Warsaw, Poland, 2022, pp. 1-7, 2023

The present work investigates the problem of creating accessible web content for users with reduc... more The present work investigates the problem of creating accessible web content for users with reduced vision and color blindness. The aim of the work is to present a model for the design and evaluation of web content with accessible color and contrast for visually impaired people. Such a model was built as part of the process of updating the web pages of Plovdiv University. It consists of the components: selection of web elements; accessibility standards and criteria; verification and validation tools; design and implementation technologies; identification of situations of dynamic change of web content; accessibility development artifacts; application approach. Its function is to reveal the perspective in gathering requirements and compiling a color and contrast specification

IPTV Monitoring via GPM3 for A1 and Vivacom

H. Hristov, S. Cheresharov, V. Valkanov and A. Ignatov, "IPTV Monitoring via GPM3 for A1 and Vivacom," 2022 IEEE 11th International Conference on Intelligent Systems (IS), Warsaw, Poland, 2022, pp. 1-6, 2023

In this paper we will explore the functionality, planning and development of our software applica... more In this paper we will explore the functionality, planning and development of our software application called General Program Monitoring-version 3 for monitoring Internet Protocol Television. The goal of this paper is to present in theory and in practice the concept of the application. The software application is used to monitor devices of users who are customers of the Bulgarian national operators A1 and Vivacom. To achieve this goal, the discussion included hardware, network and software problems, limitations and means of overcoming specific problems, software architecture, aspects of planning and programming software solutions, the process of the application's performance is presented via a finite-state machine for tracking the condition of the work cycle of monitoring et al. In conclusion a sample scenario is described for working with the application.

Method for Designing Accessible Web Content in The Web Space of "Paisii Hilenarski" Plovdiv University

by Hristo Hristov, Асен Узунов, and Milen Bliznakov

H. Hristov, S. Enkov, M. Bliznakov, A. Uzunov, Method for Designing Accessible Web Content in The Web Space of “Paisii Hilenarski” Plovdiv University. International Journal of Emerging Technologies in Learning (iJET), Vol. 17 No. 21, pp. 184-196, 2022, 2022

The article addresses the problem of accessibility of dynamic web content that is created when de... more The article addresses the problem of accessibility of dynamic web content that is created when developing web pages and services. It discusses basic issues about the accessibility of digital objects and web page content. The aim of the article is to present a method for designing accessibility in the creation of dynamic web content in websites of Paisii Hilendarski Plovdiv University. The developed method is presented through the life cycle of its model, which is applied in parallel with the implementation of a software process in the renewal of the web infrastructure of the university. The method is built on standards, principles, guidelines, accessibility criteria, and techniques for creating and validating web content of the Web Accessibility Initiative. The main standards to which the method adheres are the Web Content Accessibility Guidelines and the Technical Specifications for Accessible Rich Internet Applications. It has been tested in the design and implementation of part of the web content of the web infrastructure of the university created after 2020, which is accessible through the main domain https://uni-plovdiv.bg and many of its sub-domains.

Hierarchical Learning Management System for the Insurance Industry

by Hristo Hristov and Стоян Черешаров

S. Cheresharov, H. Hristov, V. Tabakova-Komsalova, V. Naneva, Hierarchical Learning Management System for the Insurance Industry, International Journal of Emerging Technologies in Learning (iJET), Vol. 17 No. 21. pp. 123-134, 2022 , 2022

This paper describes a model of a Hierarchical Learning Management System (HLMS) for the insuranc... more This paper describes a model of a Hierarchical Learning Management System (HLMS) for the insurance industry. The problem is that LMSs are widely used, but not suitable for each educational environment and domain. The existing LMSs are with the general purpose and do not reflect the specific needs of different domains. The proposed LMS is a specific hierarchic system specially created for the insurance industry. The model uses a hierarchic approach to share, organize and present the learning content. It allows for building an LMS specific for the insurance industry which is reliable, efficient, fast, and easy to use by the insurance professionals.

PIEZOELECTRIC CRYSTAL GENERATOR FOR ELECTRICITY GENERATION

Scientific Research of the Union of Scientists in Bulgaria – Plovdiv, series B. Natural Sciences and Humanities, Vol. XXIII, ISSN: 1311-9192 (Print), ISSN: 2534-9376 (On-line), IXth International Conference of Young Scientists, 14-15 July 2022, 2022

The paper examines electricity generation by means of an invention called "Gravitational piezoele... more The paper examines electricity generation by means of an invention called "Gravitational piezoelectric crystal generator". Said generator uses a method for electricity generation, whereby at least one piezoelectric crystal is subjected to pressure from the gravitational force of a water column. As a consequence of its deformation, the piezoelectric crystal becomes polarised and generates electrical potential. The generated electrical energy is then transported by means of an electrical circuit to the grid, a device that consumes it or to a battery for storage. The invention is patented under the name of "Piezoelectric crystal method and a device for electricity generation".

Generations of human-computer interactions: evolution, tendencies and perspectives

H. Hristov & S. Stavrev, Generations of human-computer interactions: evolution, tendencies and perspectives, Journal of Physics: Conference Series, Volume 2339, International Conference on Electronics, Engineering Physics and Earth Science 2022 (EEPES 2022) 21/06/2022 - 24/06/2022 Varna, Bulgaria, , 2022

In this paper, we present the usability evolution of human-computer interactions. In addition, we... more In this paper, we present the usability evolution of human-computer interactions. In addition, we group the various user interfaces of human-computer interaction into two generations with three classes each. The most user interfaces for human-computer interaction are assigned into a class depending on objective criteria scores, such as technical literacy level, level of natural interactions, user learning curve and UI's ability to adapt. In addition, current tendencies for HCI are presented and future perspectives are discussed. Finally, we summarize the achieved results and draw conclusions.

DESIGN TECHNIQUES AND PRACTICES OF GRID LAYOUTS AND CONTENT OF WEB PAGES

by Hristo Hristov and Николай Чочев

Chochev, N, Hristov, H., Design Techniques and Practices of Grid Layouts and Content of Web Pages,. Scientific Works of the Union of Scientists in Bulgaria - Plovdiv. Series C. Technics and Technologies. Vol. XX, ISSN 1311 -9419 (Print); ISSN 2534-9384 (Online), 2022, pp. 99-103., 2021

This paper presents the perspectives of popular web page layout design techniques and practices. ... more This paper presents the perspectives of popular web page layout design techniques and practices. Applications of basic approaches to view design are considered: from tabular design using fixed size units, through frame, fluid and elastic design by applying relative size units, to responsive design by combining different techniques and practices for adaptability. The article pays attention to current trends in which the overall look of adaptive web pages is designed through the approaches of the cascading style sheets (CSS-cascading style sheets): grid view (Grid Layout), view from flexible areas (FlexBox Layout) and Multiple Column Layout or the application of a developed framework, while the design of web page containers and their layout preserves the trend of applying techniques used in the original specifications of CSS technology. The paper analyzes some of the popular practices in designing modern adaptive web design which are important for quality search engine optimization (SEO-Search Engine Optimization), improving productivity and ease of operation of the server machine (Performance Improvement), reducing the cost and fast loading of resources on the web page in the browser of the client machine (Cost Reduction), etc.

Modeling of Pedagogical Patterns in an E-learning System

E. Hadzhikolev, S. Hadzhikoleva, H. Hristov, E. Yonchev & V. Tsvetkov, Modeling of Pedagogical Patterns in an E-learning System. International Journal of Emerging Technologies in Learning (iJET), vol. 16, no. 24, pp. 205–219, 2021, https://doi.org/10.3991/ijet.v16i24.26775, 2021

Pedagogical patterns describe teaching ideas that can be applied in different ways in teaching in... more Pedagogical patterns describe teaching ideas that can be applied in different ways in teaching in different disciplines, and for different types of students. They are a tool for sharing experience and good practices between teachers. The use of pedagogical patterns in online learning is a challenge that can be met by using an appropriate software system for learning management. The article proposes a model of educational objects, suitable for software implementation, which we call pedagogical pattern instances, or for shortinstances. One instance combines specific learning content with additional features. Learning content can have different "views" that present knowledge in different ways, for example, through text files of presentations, audio or video content, interactive content, etc. Logical categories of characteristics and activities form the "aspects" of the instance, such as methodology, adaptivity, assessment, etc. The proposed pattern instance model is flexible. It can be expanded with new features and adapted to specific goals and designs. The paper also outlines a conceptual framework of an e-learning software system using the presented model of a pattern instance.

MODELLING OF PEDAGOGICAL PATTERNS THROUGH E-LEARNING OBJECTS

H. Hristov, E. Yonchev, V. Tsvetkov, “Modelling of pedagogical patterns throughe-learning objects”, Information Technologies and Learning Tools, 2022, Vol 89, No3, ISSN: 2076-8184. , 2022

Software platforms for e-learning support various options for presenting educational content. One... more Software platforms for e-learning support various options for presenting educational content. One of the ways to organize and structure it is via so-called pedagogical patterns. They are a method for describing and sharing knowledge and practical experience. Pedagogical patterns are used to describe pedagogical situations that occur repeatedly in the learning process. In the context of e-learning systems, there are various approaches to digitalization of pedagogical patterns. The purpose of the paper is to show how to build instances of pedagogical patterns using e-learning pedagogical objects, which can be easily and conveniently used as models in an adaptive e-learning environment. An e-learning pedagogical object is an abstract concept that can be presented in the concrete form of an e-learning object, an e-learning methodological object, an e-learning object for monitoring and diagnostics or an e-learning object with learning outcomes. These objects are building blocks for constructing instances of pedagogical patterns. This paper thoroughly discusses the issue of creating instances of pedagogical patterns of the four types of e-learning pedagogical objects. The instance of a pedagogical pattern is meant to serve to create subsections of educational topics. The instances of the patterns built of e-learning objects are learning units that are used depending on the context of a particular pedagogical situation.
The e-learning pedagogical objects and the pedagogical pattern instances are intended to be applied in an adaptive e-learning environment as teaching aids. Their theoretical models are applied in Moodle LMS in line with the tendency for software to assist and replace some of the teacher functions, while the teacher’s role is raised to a higher organizational, pedagogical and methodological level.
Three instances of pedagogical patterns have been created through e-learning pedagogical objects: “Early Feedback”, “Feedback Sandwich” and “Consistent Metaphor” in LMS Moodle, which have been tested in the training course “Modeling of training courses in Moodle” during the autumn trimester of the academic year 2021/2022 at the Faculty of Mathematics and Informatics of Paisii Hilendarski University of Plovdiv, Bulgaria.

RECOGNITION OF PROBLEMATIC EDUCATIONAL SITUATIONS IN COMPUTER MODELING TRAINING

Hr. Hristov, R. Cherneva, “Recognition of problematic educational situations in computer modeling training”, Mathematics and informatics, vol. 65, no. 3, pp. 247-258, 2021, ISSN 1314 – 8532 (Online), ISSN 1310 – 2230 (Print), 2021

The article presents the results of the training in Computer Modeling in the third and fourth gra... more The article presents the results of the training in Computer Modeling in the third and fourth grades. Through the methods of participatory observation, interviews, discussions, surveys, and content analysis, data was collected, analyzed and systematized by teachers, principals, parents, university methodologists and IT administrators for problematic educational situations arising from technical reasons. An identification system was developed for their establishment. It is used to assess and measure changes in the complexity of the learning process and the workload of the teachers in the Computer Modeling subject in the event of problematic educational situations. In conclusion, guidelines for overcoming and resolving the identified unforeseen situations are provided.

КАЧЕСТВЕНО ИЗСЛЕДВАНЕ НА КОНФЕРЕНТНО ОНЛАЙН ОБУЧЕНИЕ ПРИ СТУДЕНТИ ПО УЕБ ДИЗАЙН

H. Hristov, N. Chochev, “Qualitative Research of Conference Online Learning for Web Design Students” (in Bulgarian), Mathematics and informatics, vol. 64, no. 2, pp. 207-221, 2021, ISSN 1314 – 8532 (Online), ISSN 1310 – 2230 (Print), https://doi.org/10.53656/math2021-2-7-kac, 2021

В настоящата работа е изследван процеса на конферентно онлайн обучение чрез т. нар. качествена ме... more В настоящата работа е изследван процеса на конферентно онлайн обучение чрез т. нар. качествена методология. Приложените методи на изследване са участващо наблюдение, анкетна карта, събеседване и сравнителен анализ. Обучението е проведено по дисциплината „Уеб дизайн“ чрез система на преподаване, включваща конферентна
платформа, специализирани уеб източници, дигитални облачни услуги и др. учебни материали. В статията е обърнато внимание на съществените различия между дистанционната форма на обучение и конферентното онлайн обучение при редовната форма. В нея се
дискутират характеристики на качествените методи и конферентното онлайн обучение.

Information Security in the Design of Web-Based Software Systems

by Hristo Hristov and Svetoslav Chonkov

H. Hristov, S. Cheresharov, S. Chonkov and K. Tsvetanov, "Information Security in the Design of Web-Based Software Systems," 2020 International Conference Automatics and Informatics (ICAI), 2020, pp. 1-6, doi: 10.1109/ICAI50593.2020.9311305., 2020

This article explores trends and practices in the development, integration, maintenance and opera... more This article explores trends and practices in the development, integration, maintenance and operation of web-based systems. From this point of view, issues with the information security of web applications are analyzed. Attention is drawn to the fact that information security is a phenomenon in which the greater the degree of automation of the software process, the greater number of solutions for the information security problems are concentrated in the functionality of the software. We are highlighting the advantages of modular localization in the implementation of modular web-based software systems. Even though there are various studies in this area, there are no commonly accepted solutions and guidelines for solving the problem. The article attempts to fill up this gap by proposing possible guidelines. As a result of analyzing trends in the information security applied to the web-based software systems, a forecast has been made for an increase in the regulatory requirements for software development, the need for an increased general knowledge in the society for the safe and secure use of software applications, as well as the growth in demand for highly specialized information security professionals. Modern practices are introduced for providing information security in software web-based systems through authentication and authorization modules. As a result of the studies and the analysis, guidelines are proposed for the development of a method that will provide information security.

MODEL FOR ASSESSING HIGHER ORDER THINKING SKILLS IN TRAINING IN GRAPH DATABASES

Hadzhikoleva, S., M. Borisova, E. Hadzhikolev, H. Hristov, Model for Assessing Higher Order Thinking Skills in Training in Graph Databases, ICERI2020 Proceedings, 9th-10th November 2020, pp. 6594 - 6603, ISBN: 978-84-09-24232-0, 2020

In a world where the only constant is change, only those can progress who never stop learning. Ed... more In a world where the only constant is change, only those can progress who never stop learning. Education should prepare young people for the challenges of today's dynamic world, develop their abilities for critical, logical and creative thinking. Today, more than ever, higher-order thinking skills (HOTS) are needed-transfer of knowledge and skills, critical thinking and problem solving. The need of HOTS developing in learners poses two challenges to teachers. First-they need to develop and adapt educational models, strategies and approaches for HOTS training. And second-they need to plan, implement and assess the results of conducting HOTS-oriented learning. The article presents an approach for assessing HOTS, formed during training in graph databases. Sample models of test questions classified to Bloom's taxonomy have been developed. Based on the developed models, specific test items have been created for assessing the knowledge and skills in graph databases. A complex model for HOTS assessment is proposed.

АКТИВНО, УЧАСТВАЩО НАБЛЮДЕНИЕ -ТИП ИНТЕРВЮ

H. Hristov, H. Hrushkov, “In-depth Interview”, Mathematics and informatics, vol. 59, no. 4, pp. 368-380, ISSN 1314-8532 (Online), ISSN 1310-2230 (Print). , 2016

В статията се разглеждат въпросите за същността, разработването и приложението на качествения изс... more В статията се разглеждат въпросите за същността, разработването и приложението на качествения изследователски метод "Активно, участващо наблюдение-тип интервю". Обърнато е внимание на спецификата на качествените методи, при които за различните изследвания се налага разработване на отделни, специализирани за предметната област методи. Представен е авторски разработен метод от такъв тип, който е използван при изследването на съвременни теории за създаване на софтуер и анализиране на състоянието на обучението по софтуерни технологии. За основа на разработването му е послужила качествената "Теория, основана на данни" на Б. Глейзър и А. Щраус. Посредством нея в "участващото наблюдение-тип интервю" са интегрирани ключови въпроси на методите "наблюдение" и "интервю". Той е приложен като един от методите, послужили за полагане основите на теория на методика на преподаване на софтуерни технологии.

ОБУЧЕНИЕТО ПО ИНФОРМАТИКА И СОФТУЕРНИ ТЕХНОЛОГИИ: РАЗВИТИЕ И ПЕРСПЕКТИВИ

Христов, Хр, Хр. Крушков, „Обучението по информатика и софтуерни технологии: развитие и перспективи“, Образование и технологии, Бургас, година VI, кн.6, 2015г., стр. 388-394. ISSN 1314-1791 (Print), ISSN 1314-1791 (Online), 2015

This paper traces the development of teaching informatics and software engineering in Bulgarian h... more This paper traces the development of teaching informatics and software engineering in Bulgarian higher education, which follows and pursues professional and scientific development of these areas. Prerequisites are analysed of software engineering to evolve from a discipline to bachelors and masters degree programmes. A review is made of developments and trends in the methods and tools for creation and implementation of software in the terms of software production. A model was developed based on critical analysis and evaluation, revealing prospects for future education in informatics and software engineering. Several levels of training are presented with different abstraction and difficulty called „Software practices“, „Object-oriented approaches, techniques and practises of software development“, „Modelling, creation, and application of software processes“, and „Management and implementation of software projects“.

Архитектура „Модел-изглед-контролер” в помощ на преподаването на уеб-технологии“

H. Hristov, H. Krushkov, Model view controller architecture helping in teaching of web technology, Mathematics and informatic, София, том 56(4), 2013, pp. 368-383. ISSN 1314 – 8532 (Online), ISSN 1310 – 2230 (Print), 2013

През изминалите три деситилетия и половина MVC доказа своята полезност в софтуерната индустрия. Ш... more През изминалите три деситилетия и половина MVC доказа своята полезност в софтуерната индустрия. Широката употреба на MVC е предпоставка за нейното преподаване, изучаване, и ефективно прилагане в разработването на уеб приложения. В работата се анализират трудностите, които срещат преподавателите, студентите и учениците при преподаването и изучаването на архитектура MVC. Предлага се подход на преподаване, като се представят и решения за справяне с трудностите. Подходът разглежда процеса на обучение, като разгръща преподаването на MVC върху завършеността на софтуерната разработка.

Teaching of Web Design and Programming as a Role-Playing Team Building Game

International Journal of Information and Education Technology, 2023

The paper examines a form of training whose aim is to teach technologies for designing and stylin... more The paper examines a form of training whose aim is to teach technologies for designing and styling responsive web page views and implementing web site events by students in an academic environment. In this form of training a role-play, taken by the practice of a software company is simulated. Data collection and evaluation of the results was carried out through qualitative methods of participant observation, survey, interview, and quantitative comparative analysis. The article analyzes in details the role-playing games, training content, stages of implementation and other aspects of the organization of experimental form of training in Web Design and Web Programming. Teaching, as a simulated role-playing game, is performed during six school hours, in two consecutive weeks and consists of four stages. In the role play, students apply knowledge and teamwork skills in HTML, CSS, JavaScript, jQuery etc. Each team is made up of five students with roles of manager, web designer, graphics designer, web stylist and web developer. The teams' organization is based on work products adaptation of the Rational Unified Process Methodology. The end product of the role-playing game is the development of a website by the team, while its final result for the learning process is the knowledge and skills acquired during formal training by the teacher, and the informal training that took place between the students during their teamwork.

A MODEL-BASED APPROACH TO ENHANCING WEB ACCESSIBILITY FOR INDIVIDUALS WITH SPECIAL EDUCATION NEEDs

International Journal on Information Technologies & Security, 2023

An important aspect in software development nowadays is digital opportunities for meeting the nee... more An important aspect in software development nowadays is digital opportunities for meeting the needs of disadvantaged affected people with Special Education Needs (SEN). In this article, we consider the problem of identifying and improving the accessibility of web platforms designed for users who have SEN. To achieve this goal, a model was created and implemented in the web platform sopbg.org. The specialized website, which is maintained and developed by the authors of the publication, unites a community of several thousand users with SEN. The intensive consumption of the platform provided the authors with the opportunity to make a number of improvements to the applied model, some of which should be considered.

Generations of human-computer interactions: evolution, tendencies and perspectives

Journal of Physics: Conference Series

In this paper, we present the usability evolution of human-computer interactions. In addition, we... more In this paper, we present the usability evolution of human-computer interactions. In addition, we group the various user interfaces of human-computer interaction into two generations with three classes each. The most user interfaces for human-computer interaction are assigned into a class depending on objective criteria scores, such as technical literacy level, level of natural interactions, user learning curve and UI’s ability to adapt. In addition, current tendencies for HCI are presented and future perspectives are discussed. Finally, we summarize the achieved results and draw conclusions.

An Approach to Validating the Accessibility of Dynamic Web Pages.

by Hristo Hristov and Stilian Minchev

Hr. Hristov, G. Stoitsov, M. Bliznakov, S. Minchev. (2023). An Approach to Validating theAccessibility of Dynamic Web Pages.TEM Journal, 12(1),233-240., https://www.temjournal.com/content/121/TEMJournalFebruary2023_233_240.pdf, 2023

The purpose of the publication is to present a web page validation approach that is part of a met... more The purpose of the publication is to present a web page validation approach that is part of a method for designing accessible web content. The validation approach is built on standards, principles, guidelines, success criteria and techniques for web content validation. The main standards to which the approach adheres are Web Content Accessibility Guidelines and Technical Specifications for Accessible Rich Internet Applications. The publication discusses the understanding of dynamic web content, dynamic web content design and implementation method and web content validation approach.

A Model for Designing Accessible Color and Contrast for Users with Visual Deficiency and Color Blindness

H. Hristov, T. Glushkova, S. Cheresharov and M. Stoeva, "A Model for Designing Accessible Color and Contrast for Users with Visual Deficiency and Color Blindness," 2022 IEEE 11th International Conference on Intelligent Systems (IS), Warsaw, Poland, 2022, pp. 1-7, 2023

The present work investigates the problem of creating accessible web content for users with reduc... more The present work investigates the problem of creating accessible web content for users with reduced vision and color blindness. The aim of the work is to present a model for the design and evaluation of web content with accessible color and contrast for visually impaired people. Such a model was built as part of the process of updating the web pages of Plovdiv University. It consists of the components: selection of web elements; accessibility standards and criteria; verification and validation tools; design and implementation technologies; identification of situations of dynamic change of web content; accessibility development artifacts; application approach. Its function is to reveal the perspective in gathering requirements and compiling a color and contrast specification

IPTV Monitoring via GPM3 for A1 and Vivacom

H. Hristov, S. Cheresharov, V. Valkanov and A. Ignatov, "IPTV Monitoring via GPM3 for A1 and Vivacom," 2022 IEEE 11th International Conference on Intelligent Systems (IS), Warsaw, Poland, 2022, pp. 1-6, 2023

In this paper we will explore the functionality, planning and development of our software applica... more In this paper we will explore the functionality, planning and development of our software application called General Program Monitoring-version 3 for monitoring Internet Protocol Television. The goal of this paper is to present in theory and in practice the concept of the application. The software application is used to monitor devices of users who are customers of the Bulgarian national operators A1 and Vivacom. To achieve this goal, the discussion included hardware, network and software problems, limitations and means of overcoming specific problems, software architecture, aspects of planning and programming software solutions, the process of the application's performance is presented via a finite-state machine for tracking the condition of the work cycle of monitoring et al. In conclusion a sample scenario is described for working with the application.

Method for Designing Accessible Web Content in The Web Space of "Paisii Hilenarski" Plovdiv University

by Hristo Hristov, Асен Узунов, and Milen Bliznakov

H. Hristov, S. Enkov, M. Bliznakov, A. Uzunov, Method for Designing Accessible Web Content in The Web Space of “Paisii Hilenarski” Plovdiv University. International Journal of Emerging Technologies in Learning (iJET), Vol. 17 No. 21, pp. 184-196, 2022, 2022

The article addresses the problem of accessibility of dynamic web content that is created when de... more The article addresses the problem of accessibility of dynamic web content that is created when developing web pages and services. It discusses basic issues about the accessibility of digital objects and web page content. The aim of the article is to present a method for designing accessibility in the creation of dynamic web content in websites of Paisii Hilendarski Plovdiv University. The developed method is presented through the life cycle of its model, which is applied in parallel with the implementation of a software process in the renewal of the web infrastructure of the university. The method is built on standards, principles, guidelines, accessibility criteria, and techniques for creating and validating web content of the Web Accessibility Initiative. The main standards to which the method adheres are the Web Content Accessibility Guidelines and the Technical Specifications for Accessible Rich Internet Applications. It has been tested in the design and implementation of part of the web content of the web infrastructure of the university created after 2020, which is accessible through the main domain https://uni-plovdiv.bg and many of its sub-domains.

Hierarchical Learning Management System for the Insurance Industry

by Hristo Hristov and Стоян Черешаров

S. Cheresharov, H. Hristov, V. Tabakova-Komsalova, V. Naneva, Hierarchical Learning Management System for the Insurance Industry, International Journal of Emerging Technologies in Learning (iJET), Vol. 17 No. 21. pp. 123-134, 2022 , 2022

This paper describes a model of a Hierarchical Learning Management System (HLMS) for the insuranc... more This paper describes a model of a Hierarchical Learning Management System (HLMS) for the insurance industry. The problem is that LMSs are widely used, but not suitable for each educational environment and domain. The existing LMSs are with the general purpose and do not reflect the specific needs of different domains. The proposed LMS is a specific hierarchic system specially created for the insurance industry. The model uses a hierarchic approach to share, organize and present the learning content. It allows for building an LMS specific for the insurance industry which is reliable, efficient, fast, and easy to use by the insurance professionals.

PIEZOELECTRIC CRYSTAL GENERATOR FOR ELECTRICITY GENERATION

Scientific Research of the Union of Scientists in Bulgaria – Plovdiv, series B. Natural Sciences and Humanities, Vol. XXIII, ISSN: 1311-9192 (Print), ISSN: 2534-9376 (On-line), IXth International Conference of Young Scientists, 14-15 July 2022, 2022

The paper examines electricity generation by means of an invention called "Gravitational piezoele... more The paper examines electricity generation by means of an invention called "Gravitational piezoelectric crystal generator". Said generator uses a method for electricity generation, whereby at least one piezoelectric crystal is subjected to pressure from the gravitational force of a water column. As a consequence of its deformation, the piezoelectric crystal becomes polarised and generates electrical potential. The generated electrical energy is then transported by means of an electrical circuit to the grid, a device that consumes it or to a battery for storage. The invention is patented under the name of "Piezoelectric crystal method and a device for electricity generation".

Generations of human-computer interactions: evolution, tendencies and perspectives

H. Hristov & S. Stavrev, Generations of human-computer interactions: evolution, tendencies and perspectives, Journal of Physics: Conference Series, Volume 2339, International Conference on Electronics, Engineering Physics and Earth Science 2022 (EEPES 2022) 21/06/2022 - 24/06/2022 Varna, Bulgaria, , 2022

In this paper, we present the usability evolution of human-computer interactions. In addition, we... more In this paper, we present the usability evolution of human-computer interactions. In addition, we group the various user interfaces of human-computer interaction into two generations with three classes each. The most user interfaces for human-computer interaction are assigned into a class depending on objective criteria scores, such as technical literacy level, level of natural interactions, user learning curve and UI's ability to adapt. In addition, current tendencies for HCI are presented and future perspectives are discussed. Finally, we summarize the achieved results and draw conclusions.

DESIGN TECHNIQUES AND PRACTICES OF GRID LAYOUTS AND CONTENT OF WEB PAGES

by Hristo Hristov and Николай Чочев

Chochev, N, Hristov, H., Design Techniques and Practices of Grid Layouts and Content of Web Pages,. Scientific Works of the Union of Scientists in Bulgaria - Plovdiv. Series C. Technics and Technologies. Vol. XX, ISSN 1311 -9419 (Print); ISSN 2534-9384 (Online), 2022, pp. 99-103., 2021

This paper presents the perspectives of popular web page layout design techniques and practices. ... more This paper presents the perspectives of popular web page layout design techniques and practices. Applications of basic approaches to view design are considered: from tabular design using fixed size units, through frame, fluid and elastic design by applying relative size units, to responsive design by combining different techniques and practices for adaptability. The article pays attention to current trends in which the overall look of adaptive web pages is designed through the approaches of the cascading style sheets (CSS-cascading style sheets): grid view (Grid Layout), view from flexible areas (FlexBox Layout) and Multiple Column Layout or the application of a developed framework, while the design of web page containers and their layout preserves the trend of applying techniques used in the original specifications of CSS technology. The paper analyzes some of the popular practices in designing modern adaptive web design which are important for quality search engine optimization (SEO-Search Engine Optimization), improving productivity and ease of operation of the server machine (Performance Improvement), reducing the cost and fast loading of resources on the web page in the browser of the client machine (Cost Reduction), etc.

Modeling of Pedagogical Patterns in an E-learning System

E. Hadzhikolev, S. Hadzhikoleva, H. Hristov, E. Yonchev & V. Tsvetkov, Modeling of Pedagogical Patterns in an E-learning System. International Journal of Emerging Technologies in Learning (iJET), vol. 16, no. 24, pp. 205–219, 2021, https://doi.org/10.3991/ijet.v16i24.26775, 2021

Pedagogical patterns describe teaching ideas that can be applied in different ways in teaching in... more Pedagogical patterns describe teaching ideas that can be applied in different ways in teaching in different disciplines, and for different types of students. They are a tool for sharing experience and good practices between teachers. The use of pedagogical patterns in online learning is a challenge that can be met by using an appropriate software system for learning management. The article proposes a model of educational objects, suitable for software implementation, which we call pedagogical pattern instances, or for shortinstances. One instance combines specific learning content with additional features. Learning content can have different "views" that present knowledge in different ways, for example, through text files of presentations, audio or video content, interactive content, etc. Logical categories of characteristics and activities form the "aspects" of the instance, such as methodology, adaptivity, assessment, etc. The proposed pattern instance model is flexible. It can be expanded with new features and adapted to specific goals and designs. The paper also outlines a conceptual framework of an e-learning software system using the presented model of a pattern instance.

MODELLING OF PEDAGOGICAL PATTERNS THROUGH E-LEARNING OBJECTS

H. Hristov, E. Yonchev, V. Tsvetkov, “Modelling of pedagogical patterns throughe-learning objects”, Information Technologies and Learning Tools, 2022, Vol 89, No3, ISSN: 2076-8184. , 2022

Software platforms for e-learning support various options for presenting educational content. One... more Software platforms for e-learning support various options for presenting educational content. One of the ways to organize and structure it is via so-called pedagogical patterns. They are a method for describing and sharing knowledge and practical experience. Pedagogical patterns are used to describe pedagogical situations that occur repeatedly in the learning process. In the context of e-learning systems, there are various approaches to digitalization of pedagogical patterns. The purpose of the paper is to show how to build instances of pedagogical patterns using e-learning pedagogical objects, which can be easily and conveniently used as models in an adaptive e-learning environment. An e-learning pedagogical object is an abstract concept that can be presented in the concrete form of an e-learning object, an e-learning methodological object, an e-learning object for monitoring and diagnostics or an e-learning object with learning outcomes. These objects are building blocks for constructing instances of pedagogical patterns. This paper thoroughly discusses the issue of creating instances of pedagogical patterns of the four types of e-learning pedagogical objects. The instance of a pedagogical pattern is meant to serve to create subsections of educational topics. The instances of the patterns built of e-learning objects are learning units that are used depending on the context of a particular pedagogical situation.
The e-learning pedagogical objects and the pedagogical pattern instances are intended to be applied in an adaptive e-learning environment as teaching aids. Their theoretical models are applied in Moodle LMS in line with the tendency for software to assist and replace some of the teacher functions, while the teacher’s role is raised to a higher organizational, pedagogical and methodological level.
Three instances of pedagogical patterns have been created through e-learning pedagogical objects: “Early Feedback”, “Feedback Sandwich” and “Consistent Metaphor” in LMS Moodle, which have been tested in the training course “Modeling of training courses in Moodle” during the autumn trimester of the academic year 2021/2022 at the Faculty of Mathematics and Informatics of Paisii Hilendarski University of Plovdiv, Bulgaria.

RECOGNITION OF PROBLEMATIC EDUCATIONAL SITUATIONS IN COMPUTER MODELING TRAINING

Hr. Hristov, R. Cherneva, “Recognition of problematic educational situations in computer modeling training”, Mathematics and informatics, vol. 65, no. 3, pp. 247-258, 2021, ISSN 1314 – 8532 (Online), ISSN 1310 – 2230 (Print), 2021

The article presents the results of the training in Computer Modeling in the third and fourth gra... more The article presents the results of the training in Computer Modeling in the third and fourth grades. Through the methods of participatory observation, interviews, discussions, surveys, and content analysis, data was collected, analyzed and systematized by teachers, principals, parents, university methodologists and IT administrators for problematic educational situations arising from technical reasons. An identification system was developed for their establishment. It is used to assess and measure changes in the complexity of the learning process and the workload of the teachers in the Computer Modeling subject in the event of problematic educational situations. In conclusion, guidelines for overcoming and resolving the identified unforeseen situations are provided.

КАЧЕСТВЕНО ИЗСЛЕДВАНЕ НА КОНФЕРЕНТНО ОНЛАЙН ОБУЧЕНИЕ ПРИ СТУДЕНТИ ПО УЕБ ДИЗАЙН

H. Hristov, N. Chochev, “Qualitative Research of Conference Online Learning for Web Design Students” (in Bulgarian), Mathematics and informatics, vol. 64, no. 2, pp. 207-221, 2021, ISSN 1314 – 8532 (Online), ISSN 1310 – 2230 (Print), https://doi.org/10.53656/math2021-2-7-kac, 2021

В настоящата работа е изследван процеса на конферентно онлайн обучение чрез т. нар. качествена ме... more В настоящата работа е изследван процеса на конферентно онлайн обучение чрез т. нар. качествена методология. Приложените методи на изследване са участващо наблюдение, анкетна карта, събеседване и сравнителен анализ. Обучението е проведено по дисциплината „Уеб дизайн“ чрез система на преподаване, включваща конферентна
платформа, специализирани уеб източници, дигитални облачни услуги и др. учебни материали. В статията е обърнато внимание на съществените различия между дистанционната форма на обучение и конферентното онлайн обучение при редовната форма. В нея се
дискутират характеристики на качествените методи и конферентното онлайн обучение.

Information Security in the Design of Web-Based Software Systems

by Hristo Hristov and Svetoslav Chonkov

H. Hristov, S. Cheresharov, S. Chonkov and K. Tsvetanov, "Information Security in the Design of Web-Based Software Systems," 2020 International Conference Automatics and Informatics (ICAI), 2020, pp. 1-6, doi: 10.1109/ICAI50593.2020.9311305., 2020

This article explores trends and practices in the development, integration, maintenance and opera... more This article explores trends and practices in the development, integration, maintenance and operation of web-based systems. From this point of view, issues with the information security of web applications are analyzed. Attention is drawn to the fact that information security is a phenomenon in which the greater the degree of automation of the software process, the greater number of solutions for the information security problems are concentrated in the functionality of the software. We are highlighting the advantages of modular localization in the implementation of modular web-based software systems. Even though there are various studies in this area, there are no commonly accepted solutions and guidelines for solving the problem. The article attempts to fill up this gap by proposing possible guidelines. As a result of analyzing trends in the information security applied to the web-based software systems, a forecast has been made for an increase in the regulatory requirements for software development, the need for an increased general knowledge in the society for the safe and secure use of software applications, as well as the growth in demand for highly specialized information security professionals. Modern practices are introduced for providing information security in software web-based systems through authentication and authorization modules. As a result of the studies and the analysis, guidelines are proposed for the development of a method that will provide information security.

MODEL FOR ASSESSING HIGHER ORDER THINKING SKILLS IN TRAINING IN GRAPH DATABASES

Hadzhikoleva, S., M. Borisova, E. Hadzhikolev, H. Hristov, Model for Assessing Higher Order Thinking Skills in Training in Graph Databases, ICERI2020 Proceedings, 9th-10th November 2020, pp. 6594 - 6603, ISBN: 978-84-09-24232-0, 2020

In a world where the only constant is change, only those can progress who never stop learning. Ed... more In a world where the only constant is change, only those can progress who never stop learning. Education should prepare young people for the challenges of today's dynamic world, develop their abilities for critical, logical and creative thinking. Today, more than ever, higher-order thinking skills (HOTS) are needed-transfer of knowledge and skills, critical thinking and problem solving. The need of HOTS developing in learners poses two challenges to teachers. First-they need to develop and adapt educational models, strategies and approaches for HOTS training. And second-they need to plan, implement and assess the results of conducting HOTS-oriented learning. The article presents an approach for assessing HOTS, formed during training in graph databases. Sample models of test questions classified to Bloom's taxonomy have been developed. Based on the developed models, specific test items have been created for assessing the knowledge and skills in graph databases. A complex model for HOTS assessment is proposed.

АКТИВНО, УЧАСТВАЩО НАБЛЮДЕНИЕ -ТИП ИНТЕРВЮ

H. Hristov, H. Hrushkov, “In-depth Interview”, Mathematics and informatics, vol. 59, no. 4, pp. 368-380, ISSN 1314-8532 (Online), ISSN 1310-2230 (Print). , 2016

В статията се разглеждат въпросите за същността, разработването и приложението на качествения изс... more В статията се разглеждат въпросите за същността, разработването и приложението на качествения изследователски метод "Активно, участващо наблюдение-тип интервю". Обърнато е внимание на спецификата на качествените методи, при които за различните изследвания се налага разработване на отделни, специализирани за предметната област методи. Представен е авторски разработен метод от такъв тип, който е използван при изследването на съвременни теории за създаване на софтуер и анализиране на състоянието на обучението по софтуерни технологии. За основа на разработването му е послужила качествената "Теория, основана на данни" на Б. Глейзър и А. Щраус. Посредством нея в "участващото наблюдение-тип интервю" са интегрирани ключови въпроси на методите "наблюдение" и "интервю". Той е приложен като един от методите, послужили за полагане основите на теория на методика на преподаване на софтуерни технологии.

ОБУЧЕНИЕТО ПО ИНФОРМАТИКА И СОФТУЕРНИ ТЕХНОЛОГИИ: РАЗВИТИЕ И ПЕРСПЕКТИВИ

Христов, Хр, Хр. Крушков, „Обучението по информатика и софтуерни технологии: развитие и перспективи“, Образование и технологии, Бургас, година VI, кн.6, 2015г., стр. 388-394. ISSN 1314-1791 (Print), ISSN 1314-1791 (Online), 2015

This paper traces the development of teaching informatics and software engineering in Bulgarian h... more This paper traces the development of teaching informatics and software engineering in Bulgarian higher education, which follows and pursues professional and scientific development of these areas. Prerequisites are analysed of software engineering to evolve from a discipline to bachelors and masters degree programmes. A review is made of developments and trends in the methods and tools for creation and implementation of software in the terms of software production. A model was developed based on critical analysis and evaluation, revealing prospects for future education in informatics and software engineering. Several levels of training are presented with different abstraction and difficulty called „Software practices“, „Object-oriented approaches, techniques and practises of software development“, „Modelling, creation, and application of software processes“, and „Management and implementation of software projects“.

Архитектура „Модел-изглед-контролер” в помощ на преподаването на уеб-технологии“

H. Hristov, H. Krushkov, Model view controller architecture helping in teaching of web technology, Mathematics and informatic, София, том 56(4), 2013, pp. 368-383. ISSN 1314 – 8532 (Online), ISSN 1310 – 2230 (Print), 2013

През изминалите три деситилетия и половина MVC доказа своята полезност в софтуерната индустрия. Ш... more През изминалите три деситилетия и половина MVC доказа своята полезност в софтуерната индустрия. Широката употреба на MVC е предпоставка за нейното преподаване, изучаване, и ефективно прилагане в разработването на уеб приложения. В работата се анализират трудностите, които срещат преподавателите, студентите и учениците при преподаването и изучаването на архитектура MVC. Предлага се подход на преподаване, като се представят и решения за справяне с трудностите. Подходът разглежда процеса на обучение, като разгръща преподаването на MVC върху завършеността на софтуерната разработка.