Abstract: Energy efficiency for industrial facilities can be achieved by ensuring optimal flow of the production and technological process with the required quality at minimal energy consumption. Managing energy costs in a manufacturing enterprise is a key activity in the implementation of comprehensive energy management. It is known that in dairy processing plants the refrigeration sector occupies a significant share in their energy balance. From this point of view, any organizational or technical measure leading to a reduction in energy consumption can be considered an economical and energy-efficient solution. The article discusses and analyses the factors related to the possibility of reducing energy consumption in the refrigeration sector of a milk processing plant with a capacity of 4000 l / day of milk. It examines the implementation of energy-efficient equipment in the industrial facility under consideration and analyses the environmental benefits and the reduction of CO2 emissions. The scientific novelty is demonstrated by assessing the technical feasibility and economic feasibility of integrating new energy-saving technological units, as well as by proposing new ways of organizing the work of the refrigeration sector of the milk processing plant.

Abstract: A full factorial experiment is an empirical technique used to evaluate the relationship between experimental variables and corresponding decisions. A full factorial experiment helps to develop a statistical model of response by performing a minimum number of well-chosen experiments and to determine the optimal values of the process parameters. To master the methodology of experimental research, a complete understanding of the methods of mathematical statistics and regression analysis is necessary. It is also necessary to develop the ability to analyze the object of study, correctly select the optimization parameter and the essential factors of the object of study, build a matrix for planning the experiment to obtain an adequate mathematical model of the object. In this work, a full factorial experiment was performed to determine the influencing operating and design parameters on the efficiency of the combustion device under consideration. The full factorial experiment was conducted following the reviewed and described stages and sequence of its implementation.

Abstract: This publication investigates the interaction between two gas injection burners. Previous studies conducted under isothermal conditions indicated the potential for forming a jet geometry with practical applications. These preliminary investigations revealed favorable flow characteristics that suggested the feasibility of a useful jet configuration. Subsequent experiments performed under combustion conditions demonstrated the formation of a flame with a sheet-like structure. This flame geometry implies an increased surface area of the resulting composite flame, bringing it closer to that of a planar flame. A detailed analysis is necessary to explore the feasibility of achieving a flame shape that closely resembles a flat configuration. From the perspectives of hydrodynamics and aerodynamics, it is well known that generating a planar jet poses significant challenges. However, such a flow structure can be realized through the controlled interaction of two or more free turbulent jets.

Abstract: Municipal solid waste incineration on a reciprocating step grate is the most common way of reducing the volume of landfill and generate energy as a by product. However, the complex and variable composition of RDF and the large amount of Chlorine, Sulphur, Alkali and heavy metals in the waste lead to difficult to control incineration process with frequent clinker formation and increased level of high temperature corrosion on the pressure parts and refractory anchors. This results to lower asset utilisation rate and increased maintenance cost.

Abstract: In this paper, a review is made about the technological development in Internet of Things (IoT) security over the past decade, emphasizing critical aspects such as authentication, encryption methods, and vulnerability mitigation techniques. The rapid development and widespread adoption of Internet of Things (IoT) devices have significantly increased security challenges, presenting unique vulnerabilities and threats. It outlines practical security considerations relevant to software developers and engineers, highlighting best practices and current trends in secure IoT application design. The study also briefly addresses open challenges and identifies promising future directions to guide further technological improvements in IoT security.

Abstract: VPN is a technology that creates virtual network connectivity between a user and a remote resource such as a server or corporate network using the physical and software infrastructure of a larger public network most commonly the Internet. The purpose of this paper is to present an in-depth analysis of virtual private networks (VPNs) by examining the basic concepts of deployment and configuration, their advantages and disadvantages, and the specific characteristics of VPN technologies. Special attention will be paid to the OpenVPN and L2TP protocols, their features, applications and relevance in the modern digital world. A comparative analysis of their main characteristics will be carried out by implementing VPN connectivity using MikroTik RouterOS.

Abstract: This paper introduces a parallel implementation of Impulsive Gene Regulatory Networks (GRNs) using the Message Passing Interface (MPI), with a focus on enhancing system robustness through h-manifolds analysis. Impulsive GRNs model sudden, discrete changes in gene expression that occur due to environmental or internal factors, posing challenges for accurate and scalable simulation. To address this, we develop an MPI-based framework that partitions the network into subsystems processed concurrently, enabling real-time synchronization of impulsive events. In addition to improving computational efficiency, we incorporate stability criteria to ensure the robustness of the system under uncertainty and external disturbances. This technique allows evaluation and design of gene regulatory networks that can be scalable and quick in simulation, as well as robust against changes. Simulation results demonstrate both performance gains and enhanced system stability, making this method suitable for large-scale biological modeling in high-performance computing environments.

Abstract: Semiconductor elements such as MOSFET, GTO, IGBT, IGCT, etc. are now widely used in power converters for converting electrical energy. These converters find applications in power electronics, industrial drives, telecommunications, transportation, electrical network and many other applications. are realized by heat transfer and convection Cooling technologies are realized by heat transfer and convection. In applications that use natural or forced airborne cooling, with specific coolers – radiators provide effectively heat distribution to reduce the size and weight of the converters. A review of improved stepped radiator concept density of ribs for the purpose of achieving effective isothermally cooling. Where gravity can drive liquid flow, thermosyphons provide effective heat transfer to remote areas fin volumes that can be oriented for natural and/or forced airborne cooling. Liquid cold plates (Liquid Cold Plates LCP) offer means of cooling high thermal loads and thermal flows, including bilateral cooling for the highest density packaging. LCPs can be used in both single-phase cooling water or oil systems cooling liquids, as well as in two-phase cooling systems with dielectric and refrigeration fluids. New concepts were reviewed, including an air - cooled radiator cooling, thermosiphonic radiator, LCP with vortex flow and concept of direct contact cooling.

Abstract: This paper presents a case study on the transformation of a manufacturing process in the automotive industry by automating an existing manual assembly process in order to increase efficiency, quality and productivity. The study focuses on a real industrial case related to the assembly of three components into a single Pivot Part assembly unit. A comparative analysis was performed between the manual process and a fully automated production station, using the OEE (Overall Equipment Effectiveness) indicator to assess the effectiveness. The results show a significant improvement in productivity with the automated machine – an increase in production at the automated station. By moving to a fully automated process, the impact of PLC systems (programmable logic controllers) and machine vision systems was taken into account. The integration of automatic part feeding systems was also considered. The main challenges accompanying the transition to full automation were examined: high initial investments, the need for staff training and adaptation to new technologies. The main advantages and disadvantages of the manual and automated assembly process in the context of the automotive industry are described.

Abstract: The work considers models of centralized, decentralized and distributed management for activating a social network of interacting goal-oriented participants. The behavior of the participants is conformal, i.e. when deciding to change their behavior, each participant takes into account the opinion of other participants in the network. Therefore, a change in the states of some participants at the initial moment of time leads to changes in the states of other participants. The management task consists in finding such a set of participants on which a certain initial impact is exerted, in which the network passes into the required state. An example is the task of information management in social networks. Centralized and distributed management as well as information confrontation are considered.

Abstract: The present work is devoted to the problem of dynamic control of the activation of participants in a social network in continuous time, which is formulated and solved as a choice of the number of activators introduced at each moment of time. Participants are in two states – active or inactive. Each participant makes a decision to be in one of these two states, taking into account the opinion of other participants with whom he contacts, the share of the latter determining his threshold. It is assumed that the change in the initial share of participants is described by a first-degree dynamic equation of the distribution function of the thresholds of the participants. Introducing control (adding activators) leads to a controllable dynamic system that has an equilibrium state. Initially, the reachability set and the monotonicity of the control trajectories are studied. Then, the case of continuous control is investigated. The problem of activating all participants in the social network as well as the case of positional control are also investigated.

Abstract: Nowadays, image recognition and Big Data are two facets that had practically nothing in common, but recent advances in several fields and mainly computer vision has led them to converge to perform tasks using deep machine learning such as detection, recognition and classification. In this report, an image recognition system based on Local Binary Pattern Histogram (LBPH) technique and Haar Cascade Classifier technique is presented to process real-time recognition of an object from camera. This system first prepares the data from which to extract information and perform recognition, these are photos and videos containing information on the image, then it uses Haar Cascade Classifier to perform image object detection. Thereafter, the system proceeds to the extraction of the characteristics of the points in the image to encode the shape of the latter in binary using the LBP technique. Finally the classification of the generated histograms is done which allows seeing if it is the right identified object or not.

Abstract: The rapid deployment of the Internet of Things (IoT) in various areas of household and industry is based on the construction of low-power wide-area wireless networks, taking into account the general requirements for them as automated control systems. Low-power networks allow to provide low-cost energy-efficient wireless communication for telemetry and control. One of the most important technologies in constructing such networks is the LoRa protocol, which consists of a physical layer protocol and a set of open base layer protocols. In this paper, a structural and functional analysis of approaches for implementing wireless sensor networks based on LoRa is performed, taking into account the specifics and logic of functioning at different layers in the exchange of telemetry information.

Abstract: This paper introduces the Smart Traffic Light System (STLS) as a transformative, IoT-enabled solution designed to address multifaceted challenges stemming from traffic congestion through adaptive, real-time traffic management. At its core, STLS leverages a sophisticated integration of IoT sensors, robust communication networks, advanced Artificial Intelligence (AI) and Machine Learning (ML) algorithms, and distributed computing platforms (cloud and edge computing) to dynamically optimize traffic flow in urban centers, specifically theorizing its application to key crossroads in the city of Sliven, Bulgaria. The implementation of STLS promises substantial benefits, including demonstrable reductions in traffic congestion, travel times, fuel consumption, and vehicle emissions, alongside enhanced road safety and improved emergency response times. STLS is positioned as a foundational element for the development of future smart cities, poised to revolutionize urban transportation by creating more efficient, safer, and sustainable urban environments.

Abstract: With the increasing number of renewable energy sources being put into operation—particularly stationary, grid-connected photovoltaic (PV) power plants—various technological solutions have been implemented in terms of the tilt angle of the PV panels. This article presents a comparative analysis of the productivity of grid-connected photovoltaic systems. A simulation study is conducted by varying the tilt angle of the panels, and based on the results, an optimal configuration is proposed. Conclusions and recommendations are provided

Abstract: The electrical devices and electronics that surround us are getting smarter as technology develops. Machines that mimic human intelligence and cognitive processes like learning and problem-solving are referred to as artificial intelligence. This research examines artificial neural networks, a prominent approach to logical computation. Neural networks are a desirable tool for work because of their success and ease of implementation in various application areas.

Abstract: The development offers an innovative solution for managing personal finances through a mobile and web-based FinEdge application, which combines a convenient user interface with functionalities based on artificial intelligence. The application was developed using technologies such as React for the client side and .NET Core Web API for the server logic. Its main goal is to assist users in tracking income and expenses, analyzing financial habits, creating budgets and achieving long-term financial goals. The integrated AI assistant is a significant advantage, as it provides personalized financial advice, identifies spending patterns and warns of potential risks. FinEdge stands out from competing applications such as Spendee, Monefy and 1Money through its combination of ease of use, rich functionality and intelligent assistance. The application offers data visualization, automated reports, a high level of security and accessibility from both mobile devices and desktop platforms. The application is addressed to a wide audience – from beginners to advanced users who are looking for a reliable, adaptable and technologically modern solution for managing their personal finances.

Abstract: The object of study are 6 (six) compositions of high-chromium cast iron, additionally alloyed with boron. The concentration of chromium, molybdenum and the main chemical elements for cast iron - C, Si, P, S, was maintained approximately the same, and only the content of the additional alloying element boron was changed. The studied compositions contain the following concentrations of boron, respectively: 0%, 0.18%, 0.23%, 0.59%, 0.96% and 1.25%. A quantitative X-ray analysis of the carbide (carboboride) phase and the metal base in the molten state was performed.

Abstract: Abrasive wear is responsible for hundreds of tonnes of metal loss in the mining, cement and brick industries. This necessitates the development and testing of wear resistant materials (alloys). Samples of these alloys are tested in conditions that mimic working conditions as closely as possible. The test rig developed enables the assessment of wear resistance between different materials.

Abstract: The global transformation toward a low-carbon economy has intensified interest in hydrogen as a sustainable energy vector in the transport sector. However, designing an efficient and environmentally sound hydrogen supply chain (HSC) remains a complex challenge due to the variety of production methods, storage requirements, transportation options, and environmental constraints. This study presents a mathematical model for optimal strategic design of HSC based on hydrogen production via water electrolysis. Particular focus is placed on the location of hydrogen fueling stations. The model is formulated as a mixed-integer linear programming (MILP) problem and can be solved using GAMS. It integrates economic, environmental, and social criteria to minimize carbon footprint and overall costs while supporting investment and logistical decisions in the transport sector. The proposed optimization framework offers a flexible tool for planning sustainable hydrogen infrastructure and addresses key challenges in the transition toward a hydrogen-based economy.

Abstract: The report presents the artistic design of a capsule collection of stage costumes for preschool children, developed in accordance with the principles of sustainable design. The main emphasis is placed on the integration of folklore ornaments and motifs as an expression of cultural identity. The collection is intended for use during folklore holidays in kindergartens and includes clothing inspired by traditional Bulgarian folk costumes, adapted to the age and physical characteristics of children. The models are designed with versatility and flexibility, allowing them to be worn by different age groups and body types, which contributes to their long-term use and minimizing waste. Sustainability is also reflected in the choice of materials - biodegradable fabrics such as organic cotton, linen, viscose and wool were used. The collection combines tradition, functionality and environmental responsibility, becoming an example of a modern sustainable approach to children's stage costumes.

Abstract: The development presents the possibilities for applying the traditional technique of wool felting in sustainable design for women's outerwear. Various innovative approaches proposed by fashion designers aimed at increasing the sustainability of the industry have been examined. It has been established that one of the most popular methods, which allows for the use of available resources, is the so-called upcycling. This is a process through which, by means of creative activity, new functionality and higher value are given to used items and production waste. A study was conducted on the possibilities for applying the traditional technique of wool felting to implement upcycling in clothing. Experimental samples were created using different textile materials and felting techniques. A comparative analysis was made. A new approach for implementing upcycling in women's outerwear has been proposed

Abstract: The report presents results of a study of the influence of key technological parameters on the properties of clothing made of sustainable nonwovens obtained by the wool felting method. Within the framework of the study, experimental samples were made with variations in key technological factors such as temperature, processing time, amount and distribution of fibers, as well as the use of additional materials. The physicomechanical and aesthetic characteristics of the resulting textile were analyzed, including thickness, density, flexibility and surface texture. A prototype product was made, illustrating the applicability of felted textiles in modern sustainable clothing. The results of the study contribute to optimizing the technological process and promoting sustainable practices in the textile industry

Abstract: The report presents the initial stage of the design process of a contemporary collection of sustainable luxury clothing in a national style. The created collection combines contemporary fashion trends with traditional national elements, preserving their aesthetic and cultural value. The main source of inspiration is Bulgarian embroidery, which is transformed into the models through original and artistic decorative elements. The assortment line includes a variety of semi-fitted and fitted silhouettes that emphasize femininity and provide an elegant and sophisticated look. The design solutions are aimed at combining smooth lines with functionality and freedom of movement. The patterns are created by applying basic artistic means of expression, such as symmetry, asymmetry, rhythm, similarity, contrast. The collection consists of dresses of various lengths, bustiers, shirts, pants and jumpsuits, with each garment bringing a sense of luxury and sophistication. The models in the collection are made from natural fabrics such as cotton, wool and silk, which guarantees sustainable characteristics and comfort when worn. Each model is decorated with machine-made ornaments inspired by traditional Bulgarian embroidery. The main goal of the created collection is the revival of traditional Bulgarian embroidery ornaments, which are adapted into contemporary fashion in the "luxury brand" category, affirming the Bulgarian cultural identity through an innovative design approach.

Abstract: The characteristic of children of this age group is that there are noticeable changes in the length proportions between the individual parts of the body, the neck lengthens, and the abdomen decreases in volume. Although the jacket for boys is not a typical component of children's clothing, it has its place in their wardrobe. This type of product belongs to the group of upper, shoulder garments, which are usually designed in a semi-fitted silhouette and consist of a back, side and front part. In its essential part, the product resembles the shape and topology of a men's jacket, although it has specific features that are reflected in the algorithm for sizing and building the main structure. In this material, a basic structure of a children's jacket with a double-seamed sleeve for boys of the second height group has been developed. The standard size is 140/68/58.5, (size 34), with allowances for freedom of fit along the main component lines and is without allowances for seams. Its purpose is to model on it various variants of classic woven fabrics.

Abstract: In this paper, a methodology for studying the kinematics of a DOBOT MG400 robot is proposed. The main points are related to the creation of a kinematic model using an analytical method for kinematic analysis and the construction of a block structure model in Matlab in order to implement the direct and inverse kinematics problem. A geometric model of the robot in a CAD environment has also been created for the purpose of simulation and comparison of the obtained numerical solutions in Matlab.

Abstract: – The constant increase in energy demand as a result of the growth of the Earth's population, the development of industry, climate change, the rising prices of fossil fuels, are all prerequisites for the search for alternative energy sources. Such energy sources (although with limited application in some places) are renewable energy sources. They are considered renewable or inexhaustible and include wind energy, solar energy, biomass energy, hydroelectric energy, geothermal energy and others. Solar photovoltaic panels currently available on the market convert about 20–25% of the incident solar radiation into electricity. Most of the absorbed energy is dissipated into the environment, being converted into heat. This heat increases the temperature of the photovoltaic panels, thus reducing their efficiency. In recent years, much work has been done to improve the energy efficiency of these installations. One such method is the development of hybrid photovoltaic and thermal collector systems. The advantage of this system is that it generates electrical energy and allows the absorption of thermal energy. Developed in this way, the system increases its efficiency. The purpose of this article is to present the design and construction of a hybrid PV/T system. First, the development of the supporting structure of the photovoltaic panels is described with its possibilities for changing the geographical orientation and installation inclination of the panels. Then, the construction of a hybrid system is presented, with an added solar thermal installation. The possibilities for conducting experiments and the measuring equipment used are described. The laboratory installation presented in this article would allow, in the future, the conduct of numerous experiments in order to evaluate the performance of such a PV/T system. The results obtained would allow the limits of applicability and usability of the facility to be determined.

Abstract: The scientific publication examines a beam from an experimental stand, loaded simultaneously in bending and torsion in laboratory conditions. A computational scheme has been drawn up, consistent with the tested real structure. Strain gauge equipment has been used to measure the relative linear deformations caused by the applied combined external load. The principal stresses at different load points of the arm, perpendicular to the longitudinal axis of the beam, have been experimentally calculated and their directions relative to the coordinate system of the considered structure have been determined. The results obtained experimentally have been compared with the theoretically calculated stresses by applying the classical formulas for bending and torsion. The correspondence between the experimental and theoretical results has been analyzed, reflecting the reasons for the obtained deviations. The study shows the importance of experimental verification in determining the real stress state of machine elements subjected to combined loading and confirms the application of strain gauge methods for engineering analyses. The results of the study have practical significance for greater accuracy in the design and assessment of the load-bearing capacity of machine elements in real conditions.