Customer Churn in Retail E-Commerce Business: Spatial and Machine Learning Approach

This study is a comprehensive and modern approach to predict customer churn in the example of an e-commerce retail store operating in Brazil. Our approach consists of three stages in which we combine and use three different datasets: numerical data on orders, textual after-purchase reviews and socio-geo-demographic data from the census. At the pre-processing stage, we find topics from text reviews using Latent Dirichlet Allocation, Dirichlet Multinomial Mixture and Gibbs sampling. In the spatial analysis, we apply DBSCAN to get rural/urban locations and analyse neighbourhoods of customers located with zip codes. At the modelling stage, we apply machine learning extreme gradient boosting and logistic regression. The quality of models is verified with area-under-curve and lift metrics. Explainable artificial intelligence represented with a permutation-based variable importance and a partial dependence profile help to discover the determinants of churn. We show that customers’ propensity to churn depends on: (i) payment value for the first order, number of items bought and shipping cost; (ii) categories of the products bought; (iii) demographic environment of the customer; and (iv) customer location. At the same time, customers’ propensity to churn is not influenced by: (i) population density in the customer’s area and division into rural and urban areas; (ii) quantitative review of the first purchase; and (iii) qualitative review summarised as a topic.

Hazard Reduction in Deep Excavations Execution

In this article, the authors consider a completely new approach in design, which is related to the use of previously un-adapted technologies known to bridge engineering in geotechnical issues for prestressing of diaphragm wall during deep excavations execution. The bridge technology described here is the prestressing of concrete structures. Hazards related to deep excavations and methods of digging them, such as the ceiling method and top&down method, are presented. Current problems in supporting deep excavation slopes are related to the use of extensive quantities of materials (such as steel struts, ground anchors, or concrete and reinforcement steel). The authors’ method helps to achieve a higher level of sustainability, which is important in a modern approach to geotechnical engineering. The non-linear arrangements of the cables according to the occurrence of the prestressing moments for a given phase are presented. Results related to numerical analysis—showing the correctness of the method and cost optimization results, showing possible savings are presented. The article is a part of the set. In the second (already published) article titled “Modern Methods of Diaphragm Walls Design”, the authors present the concept of the calculation methodology for diaphragm wall design.

Modelling of Mechanisms as a Methodological Tool (the Case of Designing a Cycloidal Pin Transmission)

The suggested modern approach to modelling of objects and systems allows not only to create models but also to use them to study the main properties of the object (system) with a high degree of clarity and adequacy, as well as to develop most important skills of young engineers in creating and implementing digital models of engineering objects.The objective of the study is to analyse capacity of one of the modern automated computational design systems as a methodological tool.The functionality of an automated computational design system is considered for the case of constructing a model of a planetary cycloidal pinion transmission. The resulting model allows visualising the kinematics of the designed mechanism in the form of static or moving graphic images. The model built based on the described approach contains digital images of mechanism parts, which can be transferred without modification to specialised software systems for analysing strength characteristics or manufacturing material models of a product using rapid prototyping methods.The proposed approach allows to perfect actions referring to the analysis of properties and synthesis of new structures using tools that correspond to the modern level of technology development and to get a visual idea of the process of developing a machine from a mathematical model to its material objectification.The research methods are based on the fundamental principles of mathematical and simulation modelling, data analysis and processing using powerful automated computational design tools.The tools used for modelling can be used for different forms of learning, i.e., without reference to specific premises and equipment.

A MODERN APPROACH TO MONITORING THE PROGRESS OF STUDENTS WITH THE USE OF INFORMATION AND COMMUNICATION TECHNOLOGIES

Целью статьи является обоснование эффективности проведения поэтапного мониторинга успеваемости обучающихся с применением информационно-коммуникационных технологий. Актуальность темы обусловлена тем, что важным вопросом современного образования является разработка, апробация и дальнейшее внедрение системы мониторинга качества образовательного процесса в ВУЗах. Основным методом является мониторинг, который может улучшить состояние учебного процесса путем выявления проблем и целенаправленной индивидуальной работы. В статье рассматривается алгоритм реализации поэтапного мониторинга с применением информационно-коммуникационных технологий на занятиях. По результатам проведенных исследований сделаны выводы о необходимости внедрения поэтапного мониторинга на занятиях, направленного на управление аудиторией, развитие воспитательной работы и беспристрастную оценку успеваемости обучающихся. The purpose of the article is to substantiate the effectiveness of the stage-by-stage monitoring of students' progress using information and communication technologies. The relevance of the topic is due to the fact that an important issue of modern education is the development of a system for monitoring the quality of the educational process in universities. The main method is monitoring, which can improve the state of the educational process through problems and purposeful work. The article uses the implementation of step-by-step monitoring with the use of information and communication technologies in the classroom, conducted with information technology. Based on the results of the research, conclusions were drawn about the stage-by-stage monitoring in the classroom, aimed at managing the audience, developing educational work and an impartial assessment of students' progress.

BrJAC mourns the death of Prof. Dr. Miguel Valcárcel Cases and recognizes his great contribution to Analytical Chemistry and Science around the World

Who has not seen or heard about books such as Analytical Chemistry: A Modern Approach to Analytical Science, Principles of Analytical Chemistry: A Textbook, or Foundations of Analytical Chemistry: A Teaching-Learning Approach, or about flow injection analysis-FIA, and sequential injection analysis-SIA? These are, in fact, some contributions from Prof. Miguel Valcárcel Cases, at the University of Córdoba-Spain, who leave us on 9th January 2022 at the age of 75. Prof. Valcárcel was Dean of the Faculty of Sciences at the University of Córdoba, Vice-Rector for academic guidance and teaching and Vice-Rector for quality, as well as the first Director of the Andalusian Institute of Fine Chemistry and Nanochemistry since 1994. Born in Barcelona (Spain), Prof. Valcárcel was a graduate of the University of Seville where also obtained his Ph.D., and was an assistant teacher until 1975. He was an associate professor of Analytical Chemistry at the Faculty of Science of Palma de Mallorca in 1975, an institution where he was also Dean and full professor at the University of Cordoba in the year 1976. He was also President of the Analytical Division of the European Federation of Chemical Societies and was a member for 4 years of the High-Level Expert Group of the European Union's Growth Program. Valcárcel received the Spanish national Enrique Moles prize for Chemical Science and Technology (2005), the Maimónides prize for scientific-technical research from the Junta de Andalucia (1992), and the Solvay Research Prize in Chemical Sciences from the CEOE Foundation (1997). He has the Robert Boyle Medal from the Royal Society of Chemistry (UK, 2004), the Enrich Planquette Prize from the Austrian Chemical Society (1996), the Gold Medal from the University of Warsaw (2000), and the Medal from the Portuguese Chemical Society (2000). He also received the distinction of Cordoba citizen of the year 2006 in the education/research section, and the Averroes de Oro-Cuidad de Córdoba medal in 2006 for his scientific trajectory. He was also awarded the title of Doctor Honoris Causa by the University of Valencia (2010) and the European DAC-EuChMS (Division of Analytical Chemistry of the European Association for Chemical and Molecular Sciences) award in recognition of his scientific and teaching career (2015). He was the author of ca. 700 papers, published 9 scientific books, and co-authored 15 chapters of multi-author books. Owner of a unique vitality and a very accurate vision of Analytical Chemistry, Prof. Valcárcel contributed to the formation of dozens of students, of which he was extremely proud, and some of them are today Full professors spread all over the world. The Brazilian Journal of Analytical Chemistry mourns his death, and through this simple tribute, recognizes his great contribution to Analytical Chemistry and science around the world.

Method for an Effective Selection of Tools and Cutting Conditions during Precise Turning of Non-Alloy Quality Steel C45

The paper presents a constructing methodology for a modern approach to tools selection and solving the problem of assigning optimal cutting parameters for specific production conditions. The mathematical formulation determining the extreme values of the technological process optimality criteria is obtained. A system of technical and economic quality indicators for cutting tools is proposed. This system allows principles’ implementation of decentralization and interoperability “Industry 4.0” via finite element modeling of the cutting process based on solving the problem of orthogonal free cutting modeling. The proposed methodology further usage is possible by creating a standardized database on the parameters of the tool: the adhesive component of the friction cutting coefficient for processing of a specific pair of cutting and tool materials (or tool coating material) and the impacts of the cutting-edge radius on cutting efficiency of a particular material.

Adaptation of Modern Agile Practices in Global Software Engineering

Software engineering has been an active working area for many decades. It evolved in a bi-folded manner. First research and subsequently development. Since the day of its inception, the massive number of variants and methods of software engineering were proposed. Primarily, these methods are designed to cater the time-varying need of modern approach. In this connection, the Global Software Engineering (GSE) is one of the growing trends in the modern software industry. At the same time, the employment of Agile development methodologies has also gained the significant attention in the literature. This has created a rationale to explore and adopt agile development methodology in GSE. It gained rigorous attention as an alternative to traditional software development methodologies. This paper has presented a comprehensive review on the adaptation of modern agile practices in GSE. In addition, the strength and limitation of each approach have been highlighted. Finally, the open area in the said domain is submitted as one of the deliverables of this work.

INCLUSIVE ORIENTATION OF THE EDUCATION SYSTEM IN UKRAINE

Under the influence of global processes of humanization, modern Ukrainian society is changing its attitude towards people with disabilities. These changes can be seen as overcoming social and educational barriers.One of these barriers is the traditional division of education into general secondary and special (correctional), which are represented by segregation institutions. But the modern approach to the development of education breaks down this barrier.Integration processes into the European community determine the urgency of the problem of inclusive education. It is primarily due to the fact that the number of children in need of remedial education is growing steadily. The emergence of the ideology of inclusive education is due to the need to improve the system of organization of children’s education. This improvement is to create a single educational space for each child.The term “inclusion” differs from the terms “integration” and “segregation”. With inclusion, all stakeholders must be actively involved to achieve the desired result. Recognizing the value of inclusive education, it is necessary to take into account certain factors that hinder the implementation of the ideas of inclusive education. We believe that this is primarily not a tolerant attitude of the population to children with disabilities, psychological unwillingness to accept these children as full members of society. But despite the emerging disputes and disagreements, the system of inclusive education is an effective mechanism for the development of an inclusive society. This is the key to inclusive education. Rejecting all misunderstandings, we can say that inclusive education is education for all, regardless of their physical, intellectual, social, emotional, linguistic or other characteristics. It gives the opportunity to join the general process of learning and education (development and socialization), which then allows an adult to become an equal member of society. In general, an inclusive form of education and upbringing is a long-term strategy.The development of inclusive education in Ukraine requires the creation of a barrier-free environment that includes physical and psychological components. Special work with the use of additional education resources on the organization of interaction of children with and without disabilities, aimed at harmonizing children’s relationships; creating an atmosphere of emotional comfort and mutual acceptance. By changing society’s attitude towards children with disabilities, the process of integrating such children into secondary schools will gain popularity and become successful. A well-organized inclusive education will help parents of children to look at the phenomenon of integration in a new way and provide evidence that children with disabilities will not only not harm their children to full development, but will also provide additional opportunities.