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Open AccessEditorial

Statement of Peer Review

by Nikolay Kakanakov and Sevil Ahmed-Shieva

Eng. Proc. 2025, 100(1), 67; https://doi.org/10.3390/engproc2025100067 - 15 Aug 2025

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Abstract

In submitting conference proceedings to Engineering Proceedings, the volume editors of the proceedings certify to the publisher that all papers published in this volume have been subjected to peer review administered by the volume editors [...] Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

2 pages, 151 KB

Open AccessEditorial

Preface of the 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems

by Sevil Ahmed-Shieva, Nikolay Kakanakov, Nikola Shakev and Valyo Nikolov

Eng. Proc. 2025, 100(1), 68; https://doi.org/10.3390/engproc2025100068 - 15 Aug 2025

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Abstract

The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems was organized by the Technical University of Sofia, Plovdiv Branch, within the frame of “Science Days of Technical University of Sofia” and supported by the University Scientific and Research Sector [...] Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

Other

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6 pages, 2316 KB

Open AccessProceeding Paper

Simulation of Gravity Filling in a Silica Sand Mold with Gray Cast Iron (EN-GJL-250)

by Krum Petrov, Antonio Nikolov and Anton Mihaylov

Eng. Proc. 2025, 100(1), 1; https://doi.org/10.3390/engproc2025100001 - 25 Jun 2025

Viewed by 1015

Abstract

This study presents a simulation modeling of the gravity filling of a sand casting mold with gray cast iron EN-GJL-250. An analysis of the fluid flow, the nature of the filling of the casting mold, and the possibility of forming defects, such as [...] Read more.

This study presents a simulation modeling of the gravity filling of a sand casting mold with gray cast iron EN-GJL-250. An analysis of the fluid flow, the nature of the filling of the casting mold, and the possibility of forming defects, such as voids and porosity due to metal shrinkage during the crystallization process, was performed. The simulation was performed using specialized software for simulating metal casting processes. The software allows the modeling of fluid dynamics and thermal conditions during the filling of the casting mold. The results obtained show the influence of the design of the sprue system, pouring temperature, and casting geometry on the movement of the fluid flow and the crystallization of the metal. The simulation also allows the visualization of turbulence and temperature gradients, helping to localize areas prone to defects. The results of this study could improve the quality of the specific casting and aid in selecting appropriate technology for the casting of a small series of high-quality castings. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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12 pages, 938 KB

Open AccessProceeding Paper

Energy Management of Charging Stations for Electric Vehicles

by Todor Stoilov, Krasimira Stoilova and Denis Chikurtev

Eng. Proc. 2025, 100(1), 2; https://doi.org/10.3390/engproc2025100002 - 26 Jun 2025

Viewed by 994

Abstract

The energy distribution between several charging stations for electric vehicles (EVs) is considered. An optimization problem is defined that aims to minimize the service time for EV charging. The charging sequence is evaluated and determined in view of the energy capacity constraint that [...] Read more.

The energy distribution between several charging stations for electric vehicles (EVs) is considered. An optimization problem is defined that aims to minimize the service time for EV charging. The charging sequence is evaluated and determined in view of the energy capacity constraint that is allocated to the set of stations. Empirical simulations and comparisons are performed to prove the “shorter EV charging capacity first” charging policy. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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11 pages, 1502 KB

Open AccessProceeding Paper

A Methodology for Modernization of Hydropower Unit in Pumped Hydro Energy Storage Systems

by Georgi Todorov, Konstantin Kamberov and Tsvetan Tsalov

Eng. Proc. 2025, 100(1), 3; https://doi.org/10.3390/engproc2025100003 - 26 Jun 2025

Viewed by 1792

Abstract

This study aims to preview the possibilities for the modernization of pumped hydro energy storage systems, using actual engineering tools. The survey starts with a detailed analysis of the existing approaches and practices. Furthermore, a detailed methodology is developed and commented on in [...] Read more.

This study aims to preview the possibilities for the modernization of pumped hydro energy storage systems, using actual engineering tools. The survey starts with a detailed analysis of the existing approaches and practices. Furthermore, a detailed methodology is developed and commented on in detail. The major aim of this methodology is to evaluate both the technical and economic aspects of the modernization and to obtain maximal output of the system. The methodology involves the assessment of the current state of the art of the examined structures, using virtual prototyping techniques that are later combined with reliability prediction and failure modes and effects analysis, to be used together with a financial analysis of possible solutions. A primer of experienced damage in existing infrastructure further demonstrates the developed methodology. Its examination shows possible rehabilitation methods that are commented on and targeted for future detailed evaluation. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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7 pages, 581 KB

Open AccessProceeding Paper

Non-Linear Investigation of a Functionally Graded Pipe

by Victor Rizov

Eng. Proc. 2025, 100(1), 4; https://doi.org/10.3390/engproc2025100004 - 30 Jun 2025

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Abstract

A pipe subjected to an evenly distributed internal pressure is investigated in this theoretical paper. The pipe has a thin wall that is built-up by a functionally graded engineering material. The circumferential stresses and strains in the pipe wall are investigated. In essence, [...] Read more.

A pipe subjected to an evenly distributed internal pressure is investigated in this theoretical paper. The pipe has a thin wall that is built-up by a functionally graded engineering material. The circumferential stresses and strains in the pipe wall are investigated. In essence, the current investigation is non-linear since the wall behaves as a non-linear elastic body with non-linearly distributed properties through the wall thickness. The different stages of the work of the wall are investigated and the corresponding parameters of stressed and strained state are derived. The dependence of the pressure on the material and geometrical parameters are studied. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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6 pages, 229 KB

Open AccessProceeding Paper

Reliability of Electro-Power Equipment Determined by Data in Its Operation and Storage

by Nikolay Gueorguiev, Atanas Nachev, Yavor Boychev, Konstantin Nesterov and Svetlana Yaneva

Eng. Proc. 2025, 100(1), 5; https://doi.org/10.3390/engproc2025100005 - 1 Jul 2025

Cited by 1 | Viewed by 692

Abstract

The reliability of the electro-power equipment of electrical power transmission systems is essential in ensuring an uninterrupted power supply with the necessary voltage and frequency stability. This is especially important when performing lengthy procedures requiring the serviceability of the electrical equipment used, such [...] Read more.

The reliability of the electro-power equipment of electrical power transmission systems is essential in ensuring an uninterrupted power supply with the necessary voltage and frequency stability. This is especially important when performing lengthy procedures requiring the serviceability of the electrical equipment used, such as those related to foundries and metallurgical processes, or with the processes of testing complex means for the remote control of electromagnetic radiation within the implementation of the Sustainable development of the Competence Center “Quantum Communication, Intelligent Security Systems and Risk Management” (QUASAR) Project, funded with the participation of the EU under the “Research, Innovation and Digitalization for Smart Transformation” Program 2021.2027 according to procedure BG16RFPR002-1.014. One of the main issues in this case is related to the availability of information regarding the technical condition of the deployed or reserve energy resources. In this connection, this study proposes methods for determining the quantity of operational equipment that is either in use or in storage, based on the reliability testing of a representative sample of it. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

19 pages, 946 KB

Open AccessProceeding Paper

Tariff Responses: A Graph-Theoretic Approach with Industry Dependencies

by George Pashev and Silvia Gaftandzhieva

Eng. Proc. 2025, 100(1), 6; https://doi.org/10.3390/engproc2025100006 - 1 Jul 2025

Cited by 1 | Viewed by 1173

Abstract

In response to the growing prevalence of tariffs as instruments of economic policy and strategic competition, this paper introduces a formal mathematical framework for optimizing counter-tariff strategies. We model the global trade ecosystem as a multi-layered, directed, weighted hypergraph, where vertices represent countries, [...] Read more.

In response to the growing prevalence of tariffs as instruments of economic policy and strategic competition, this paper introduces a formal mathematical framework for optimizing counter-tariff strategies. We model the global trade ecosystem as a multi-layered, directed, weighted hypergraph, where vertices represent countries, industries, and subindustries, and hyperedges capture complex trade relationships and supply chain dependencies. The proposed framework employs bilevel optimization techniques to maximize strategic impact on target economies while minimizing self-inflicted economic costs. Through integration of graph theory, spectral analysis, and multilevel optimization methods, we develop a rigorous formalism that enables policymakers to identify optimal counter-tariff portfolios under various constraints. Our model explicitly accounts for industrial interdependencies, where export competitiveness depends on imported inputs, thus providing a more realistic representation of global value chains. Case studies applying our model to historical trade disputes demonstrate its capacity to generate superior strategic outcomes compared to conventional approaches. The framework’s axiomatic foundation allows for rapid recalibration in response to shifting economic conditions and policy objectives. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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6 pages, 460 KB

Open AccessProceeding Paper

Non-Linear Creep of Spherical Container with Fluid Under Increasing Pressure

by Victor Rizov

Eng. Proc. 2025, 100(1), 7; https://doi.org/10.3390/engproc2025100007 - 1 Jul 2025

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Abstract

This paper presents an analysis of the time-dependent response of a spherical container to internal pressure that increases over time. The wall of the container is relatively thin, in the sense that the wall thickness is negligible in comparison to the container’s radius. [...] Read more.

This paper presents an analysis of the time-dependent response of a spherical container to internal pressure that increases over time. The wall of the container is relatively thin, in the sense that the wall thickness is negligible in comparison to the container’s radius. The wall is composed of three layers. The two surface layers of the wall are identical, i.e., they are made from the same material and have the same thickness. One of the most important features regarding the response of the wall layers is the non-linear creep. The stresses and strains are determined, and their relationships with the parameters of the layers are studied. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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9 pages, 1742 KB

Open AccessProceeding Paper

Investigation of the Efficiency of a Peltier Element

by Atanas Radulov, Mario Dechev and Misho Matsankov

Eng. Proc. 2025, 100(1), 8; https://doi.org/10.3390/engproc2025100008 - 1 Jul 2025

Cited by 2 | Viewed by 1737

Abstract

This paper presents the implementation of a modern approach for automatic measurement, data acquisition, and processing using custom-developed software based on the ARDUINO version: 2.3.6 platform. State-of-the-art sensing elements are employed for enhanced precision and reliability. The obtained results are graphically visualized for [...] Read more.

This paper presents the implementation of a modern approach for automatic measurement, data acquisition, and processing using custom-developed software based on the ARDUINO version: 2.3.6 platform. State-of-the-art sensing elements are employed for enhanced precision and reliability. The obtained results are graphically visualized for comprehensive analysis. The ARDUINO microcontroller and its associated open-source programming environment are primarily designed for general-purpose users rather than specialized industrial applications. The study focuses on the experimental investigation of the characteristics of a Peltier element. The interdependence between current, voltage, internal resistance, and temperature differential is examined in detail. The findings concerning efficiency analysis are intended to support students across various engineering disciplines during their educational process. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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9 pages, 2824 KB

Open AccessProceeding Paper

Approaches to Creating Colorful 3D-Printed Parts and Reliefs

by Mihail Zagorski, Radoslav Miltchev, Boyan Dochev and Nikolay Stoimenov

Eng. Proc. 2025, 100(1), 9; https://doi.org/10.3390/engproc2025100009 - 2 Jul 2025

Cited by 1 | Viewed by 1394

Abstract

The present article aims to examine different approaches and technologies for producing multi-color 3D printed parts and reliefs using FDM/FFF printing technology. Several examples of parts used in the fields of technology, architecture, marketing and art are presented. The innovative HueForge software version [...] Read more.

The present article aims to examine different approaches and technologies for producing multi-color 3D printed parts and reliefs using FDM/FFF printing technology. Several examples of parts used in the fields of technology, architecture, marketing and art are presented. The innovative HueForge software version 0.8.1 is used to create a multi-color relief. The process of establishing the Transmission Distance parameter of a given filament, which is key to creating colored reliefs with HueForge, is also examined. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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16 pages, 7834 KB

Open AccessProceeding Paper

Exploring the Connection Between Design and Materials Through the Digitalization of Modular Solutions

by Mihaela Gadzheva-Nedelcheva and Ivelina Daulova

Eng. Proc. 2025, 100(1), 10; https://doi.org/10.3390/engproc2025100010 - 3 Jul 2025

Cited by 1 | Viewed by 782

Abstract

This research presents a methodically consistent creative act related to the digitization of planar pictorial images. After the transformation based on the modular grids, completely new images are created—different from their original source. The successful solutions found in this way are applicable to [...] Read more.

This research presents a methodically consistent creative act related to the digitization of planar pictorial images. After the transformation based on the modular grids, completely new images are created—different from their original source. The successful solutions found in this way are applicable to various areas of graphic and product design. Multiple experiments were conducted in a digital environment on the same image applied to different material carriers in relation to the function of the product—different types of textiles and paper. To more accurately describe the experiments, three-dimensional realistic shapes from different materials have been created, onto which the modular designs have been applied. The report provides a methodical modular principle of thinking and action, justified by the applied results of the set experiment. The experiment was conducted and directly implemented under a scientific research project for an R&DS (The Research and Development Sector) project (Agrmt. 241XTД0006-06) at the Technical University, Sofia. The study involved three students from the Engineering Design Department, as well as the authors of this article—all supporters of the creative principle. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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8 pages, 1970 KB

Open AccessProceeding Paper

Optimization of Accuracy and Repeatability in Laser Micro-Processing Using Experimental Design

by Todor Gavrilov, Todor T. Todorov, Yavor Sofronov, Hristiana Nikolova and Angel Todorov

Eng. Proc. 2025, 100(1), 11; https://doi.org/10.3390/engproc2025100011 - 2 Jul 2025

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Abstract

This study focuses on optimizing the laser micromachining process to achieve precise geometric features. The main objective is to develop a systematic approach for analyzing the process parameters that influence the repeatability of laser material removal for edge-rounding of 50 and 75 μm [...] Read more.

This study focuses on optimizing the laser micromachining process to achieve precise geometric features. The main objective is to develop a systematic approach for analyzing the process parameters that influence the repeatability of laser material removal for edge-rounding of 50 and 75 μm in radius. The research employs the Taguchi method for the experimental design, allowing the identification of optimal process parameters that ensure high consistency. Repeatability is assessed through the evaluation of eight consecutive layers in depth, where the laser removes material, and the average depth is calculated by dividing the total removed depth by eight. This statistical approach allows for a comprehensive analysis of process stability. A key aspect of this study is the development of a predictive model based on experimental data, allowing a selection of the most influential parameters to achieve the desired outcome. By implementing a structured optimization process, this research aims to enhance process efficiency, minimize deviations, and improve the overall quality of laser micromachining. These findings contribute to the advancement of precision manufacturing techniques by providing a reliable methodology for process control and repeatability enhancement. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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8 pages, 830 KB

Open AccessProceeding Paper

Process Optimization with Smart BLE Beacons

by Stanimir Kabaivanov and Veneta Markovska

Eng. Proc. 2025, 100(1), 12; https://doi.org/10.3390/engproc2025100012 - 3 Jul 2025

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Abstract

The optimization of workflows and processes based on available data and observations is very important for gaining efficiency, but is often limited by the amount of available information and the time required to collect it. In this paper we suggest a flexible solution, [...] Read more.

The optimization of workflows and processes based on available data and observations is very important for gaining efficiency, but is often limited by the amount of available information and the time required to collect it. In this paper we suggest a flexible solution, based on wearable radio beacons and software analysis of their inputs. A prototype of the system was built with NRF52832 smart tags and the Raspberry Pi 4 gateway and data analysis system. Experiments carried out on the first samples indicate that it is indeed possible to seamlessly collect and process information that is then used to optimize various actions, ranging from production to administrative tasks. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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14 pages, 1805 KB

Open AccessProceeding Paper

Helicopter Rotor Aerodynamic Characteristics in Ground Effect: Numerical Study

by Gabriel Georgiev

Eng. Proc. 2025, 100(1), 13; https://doi.org/10.3390/engproc2025100013 - 4 Jul 2025

Cited by 2 | Viewed by 2423

Abstract

This article represents a full estimation of helicopter rotor aerodynamic characteristics in ground effect conditions through the application of a coupled empirical blade element–momentum theory algorithm. The main focus of this research includes the evaluation of the required weighted power coefficients [...] Read more.

This article represents a full estimation of helicopter rotor aerodynamic characteristics in ground effect conditions through the application of a coupled empirical blade element–momentum theory algorithm. The main focus of this research includes the evaluation of the required weighted power coefficients

(\frac{C_{P}}{σ})

for a hovering state in close proximity to obstacles and their relation to the weighted thrust force coefficients’ values

(\frac{C_{T}}{σ}),

varying the relative distance from the helicopter rotational plane to the ground surface

(\frac{H}{R})

and the rotor’s collective pitch angle (θ). The represented numerical and experimental results show that an increase in the collective pitch angles (θ) leads to a rise in the generated weighted thrust force coefficients

(\frac{C_{T}}{σ})

and in the weighted power coefficients

(\frac{C_{P}}{σ})

for every individual fixed normalized distance from the ground surface

(\frac{H}{R})

. Moreover, a decline in the relative distance from the ground

(\frac{H}{R})

requires less power to keep the rotation going in hover. The dependencies indicate that the ground effect zone covers a distance of up to 2R from the rotational plane to the ground surface. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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8 pages, 1954 KB

Open AccessProceeding Paper

Ensuring Accuracy in Turning

by Svetlana Koleva

Eng. Proc. 2025, 100(1), 14; https://doi.org/10.3390/engproc2025100014 - 4 Jul 2025

Viewed by 855

Abstract

At the stage of the final processing of surfaces, the quality indicators of the surfaces of parts—size, shape in cross-section and longitudinal section, mutual arrangement of surfaces, and roughness—are obtained. This includes technical and organizational measures and activities that are laid down or [...] Read more.

At the stage of the final processing of surfaces, the quality indicators of the surfaces of parts—size, shape in cross-section and longitudinal section, mutual arrangement of surfaces, and roughness—are obtained. This includes technical and organizational measures and activities that are laid down or taken into account in the applied technology. This publication constructs cause-and-effect diagrams of the factors influencing the achievement of each of these accuracy indicators. Ways to reduce the negative impact of some factors are indicated. Errors related to the components of the technological system are analyzed and grouped. Tasks related to accurate process design are defined. Guidelines related to structural accuracy design are given. The technological conditions for ensuring the accuracy of finishing operations when processing parts by turning are formulated. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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10 pages, 2832 KB

Open AccessProceeding Paper

Gaining Python Skills Through Interactive Education Robot Ozobot EVO

by Maya Staikova

Eng. Proc. 2025, 100(1), 15; https://doi.org/10.3390/engproc2025100015 - 4 Jul 2025

Viewed by 1679

Abstract

This paper explores the potential of the Ozobot EVO mobile robot as an educational tool for teaching Python programming. While the robot is currently designed for younger students through color and block programming, it is not yet widely utilized for teaching text-based coding. [...] Read more.

This paper explores the potential of the Ozobot EVO mobile robot as an educational tool for teaching Python programming. While the robot is currently designed for younger students through color and block programming, it is not yet widely utilized for teaching text-based coding. The Ozobot’s compatibility with Python presents a valuable opportunity for students to visualize their programming concepts through the robot’s actions, offering a more engaging alternative to console-based learning. The increasing use of the Raspberry Pi, a single-board computer programmed in Python, has necessitated the inclusion of Python in the curriculum. However, students often find learning Python challenging and demotivating. To enhance STEM education and student motivation, this paper proposes sample Python code for the Ozobot EVO, aiming to encourage educators to integrate the robot into their teaching. I suggest some Python code examples for the Ozobot EVO. This is to help educators see how they can use the robot in their lessons. Specifically, code examples for controlling motion, sound, light, and combinations of these functionalities are presented. When students see the robot react immediately to their code, they can understand programming ideas much better than just seeing text in the Python console. The Ozobot EVO mobile robot offers a solid foundation for learning Python programming. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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13 pages, 5812 KB

Open AccessProceeding Paper

Development of an Educational Omnidirectional Mobile Manipulator with Mecanum Wheels

by Nayden Chivarov, Radoslav Vasilev, Maya Staikova and Stefan Chivarov

Eng. Proc. 2025, 100(1), 16; https://doi.org/10.3390/engproc2025100016 - 4 Jul 2025

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Abstract

The developed omnidirectional mobile manipulator is an educational omnidirectional mobile manipulator that utilizes the Raspberry Pi Pico W and is programmed in Python. It is designed to enhance STEM education by providing an interactive environment for studying robotics, sensor integration, and programming techniques. [...] Read more.

The developed omnidirectional mobile manipulator is an educational omnidirectional mobile manipulator that utilizes the Raspberry Pi Pico W and is programmed in Python. It is designed to enhance STEM education by providing an interactive environment for studying robotics, sensor integration, and programming techniques. The robot is built on an off-the-shelf chassis equipped with Mecanum wheels and a robotic arm actuated by servo motors. As part of this project, the control electronics were designed and implemented to enable seamless operation. While the platform allows students to program the robot as part of the STEM curriculum, our base software solution, developed in Python, provides control of both the mobile base and the robotic arm via a web interface accessible through the robot’s Wi-Fi hotspot. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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6 pages, 525 KB

Open AccessProceeding Paper

LoRaWAN IoT System for Measuring Air Parameters in a Traffic Monitoring Station

by Stefan Lishev, Grisha Spasov and Galidiya Petrova

Eng. Proc. 2025, 100(1), 17; https://doi.org/10.3390/engproc2025100017 - 7 Jul 2025

Cited by 3 | Viewed by 3395

Abstract

Traffic measurement systems are an essential part of intelligent transportation systems (ITS). These are specialized transport infrastructures where traffic data is collected and analyzed in order to optimize the use of road systems, improve transport safety, and implement future transport plans. The rapid [...] Read more.

Traffic measurement systems are an essential part of intelligent transportation systems (ITS). These are specialized transport infrastructures where traffic data is collected and analyzed in order to optimize the use of road systems, improve transport safety, and implement future transport plans. The rapid development of transportation systems, urbanization, and industrialization have led to a global problem of air pollution. This has raised the topical issue of measuring and monitoring environmental parameters at traffic monitoring stations in ITS. In this paper, we present a wireless environmental monitoring system, which is a subsystem of a traffic monitoring station. Along with measuring traffic parameters, the station also collects useful meteorological information. A novel hybrid, dual-band IoT system based on LoRa and LoRaWAN for environmental parameters monitoring is presented. The hardware realization of a developed hybrid LoRaWAN end device, together with the sensors used for the measurement of air parameters, is described. Initial results from real test monitoring of environmental parameters on the road in urban environments are presented as a proof of concept. The presented wireless environmental monitoring system can also be used for indoor or outdoor air pollution monitoring, serving as a useful complement to intelligent transport systems. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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7 pages, 532 KB

Open AccessProceeding Paper

FPGA Prototyping of Heterogeneous Security Architecture for Educational Purposes

by Stefan Stoyanov, Nikolay Kakanakov and Maria Marinova

Eng. Proc. 2025, 100(1), 18; https://doi.org/10.3390/engproc2025100018 - 7 Jul 2025

Cited by 2 | Viewed by 1007

Abstract

Modern day hardware design is heavily focused on software simulations and verification. ASIC design is complex, and its abstraction may lead to losing motivation to develop knowledge and skills in the field. It is also very costly and inaccessible outside the industry, especially [...] Read more.

Modern day hardware design is heavily focused on software simulations and verification. ASIC design is complex, and its abstraction may lead to losing motivation to develop knowledge and skills in the field. It is also very costly and inaccessible outside the industry, especially on a larger scale. FPGAs are devices which are affordable and allow unexperienced people, like students, to have an accessible and observable starting point in hardware development. On the other hand, protocol standards and devices nowadays are so complex that one will need to spend years to understand and feel comfortable dealing with corporate methodologies, environments and development process. One of the still evolving, recently developed ISA for example, RISC-V, is a broad area to learn. Often the fastest and in-depth way to learn is by observation, getting familiar with accessible yet challenging design and making modifications to and experimenting with such platforms. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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9 pages, 249 KB

Open AccessProceeding Paper

Applications of Virtual Reality Simulations and Machine Learning Algorithms in High-Risk Environments

by Velyo Vasilev, Dilyana Budakova and Veselka Petrova-Dimitrova

Eng. Proc. 2025, 100(1), 19; https://doi.org/10.3390/engproc2025100019 - 7 Jul 2025

Cited by 1 | Viewed by 1558

Abstract

In this article, the application of virtual reality technology for the realistic and immersive visualization of various tasks and scenarios in fields such as power engineering and fire safety has been examined in order to help prepare students and professional electrical engineers with [...] Read more.

In this article, the application of virtual reality technology for the realistic and immersive visualization of various tasks and scenarios in fields such as power engineering and fire safety has been examined in order to help prepare students and professional electrical engineers with electrical safety, the operation of electrical substations, potential emergencies, injury prevention, fire safety, and others. Additionally, the use of machine learning algorithms to guide evacuations from hazardous environments, fault prevention, fire prediction, and discovery of conductive materials has been examined. The most frequently used algorithms in these areas have also been described and summarized, and conclusions have been made about the combined advantages of using VR and ML algorithms. Finally, the needs, contributions, and challenges of using machine learning in virtual reality projects have been examined. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

6 pages, 904 KB

Open AccessProceeding Paper

Determination of the Size of an Astronomical Object Using Photon Counting Mode

by Boryana Pachedjieva

Eng. Proc. 2025, 100(1), 20; https://doi.org/10.3390/engproc2025100020 - 8 Jul 2025

Viewed by 460

Abstract

A methodology for radiometric determination of the size of an astronomical object using photon counting mode is proposed in this study. An algorithm for applying the methodology is developed. The measurement accuracy and value of the characteristic coefficient of the photon counting mode [...] Read more.

A methodology for radiometric determination of the size of an astronomical object using photon counting mode is proposed in this study. An algorithm for applying the methodology is developed. The measurement accuracy and value of the characteristic coefficient of the photon counting mode are investigated. A numerical determination of the size of an astronomical object is developed with simulated experimental data and example measurement system parameters. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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8 pages, 1034 KB

Open AccessProceeding Paper

Investigation of the Mechanical Properties of Thermosetting Polymers Reinforced with Carbon Particles

by Boyan Dochev, Desislava Dimova, Mihail Zagorski, Filip Ublekov, Nikola Tomanov and Daniela Valeva

Eng. Proc. 2025, 100(1), 21; https://doi.org/10.3390/engproc2025100021 - 7 Jul 2025

Cited by 1 | Viewed by 764

Abstract

In this work, the mechanical properties of composites with a polymer matrix and reinforced with carbon particles have been studied. It has been established that the obtained engineering materials have increased elastic and plastic characteristics. The thermosetting polymers used are epoxy, polyester, and [...] Read more.

In this work, the mechanical properties of composites with a polymer matrix and reinforced with carbon particles have been studied. It has been established that the obtained engineering materials have increased elastic and plastic characteristics. The thermosetting polymers used are epoxy, polyester, and vinylester resins. The carbon particles are carbon nanotubes and waste carbon from the plasma decomposition of methane in the production of green hydrogen. The carbon particles used are in an amount of 1 wt% and 2 wt% of the weight of the composite, and they are not subjected to pre-treatment (modification). The studied composites are used in shipping, automotive, and aviation technology, and the presence of carbon particles in them is a prerequisite for improving their anti-radar properties. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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10 pages, 3944 KB

Open AccessProceeding Paper

Modelling and Optimization of the Precision Hot Forging/Extrusion Process of an Asymmetric C45E/1.1191 Carbon Steel Bearing Element

by Antonio Nikolov, Anton Mihaylov and Dimiter Yankov

Eng. Proc. 2025, 100(1), 22; https://doi.org/10.3390/engproc2025100022 - 8 Jul 2025

Viewed by 1615

Abstract

Precision extrusion forging is an innovative manufacturing process for trouble-free production of high-quality components with an accurate shape. The process provides a reduced technological chain and high production efficiency, as only certain surfaces need additional processing. This study used QForm software as an [...] Read more.

Precision extrusion forging is an innovative manufacturing process for trouble-free production of high-quality components with an accurate shape. The process provides a reduced technological chain and high production efficiency, as only certain surfaces need additional processing. This study used QForm software as an environment for simulating precision extrusion forging. The main goal of this research was to present a brief overview of the latest research on the simulation of precision extrusion forging, with an emphasis on the production cycle rather than on mathematical description. This article examines the processes of simulation modeling of precision extrusion forging with newly designed tooling for the manufacture of a newly introduced asymmetric load-bearing facade element patented by Braykov. With the help of simulation modeling, appropriate modes for specific production were established, and were later implemented. The production process itself is briefly presented at the end of this article. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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8 pages, 880 KB

Open AccessProceeding Paper

An Algorithm for Assessment of Time Series Data Related to the Materials Used for Packaging in the Market

by Delyana Dimova

Eng. Proc. 2025, 100(1), 23; https://doi.org/10.3390/engproc2025100023 - 8 Jul 2025

Viewed by 564

Abstract

This article presents an algorithm for the assessment of time series data related to the materials used for packaging in the market in Bulgaria for the period 2010–2023. The considered elements include the quantities of the following types of materials: paper/cardboard, plastic, wood, [...] Read more.

This article presents an algorithm for the assessment of time series data related to the materials used for packaging in the market in Bulgaria for the period 2010–2023. The considered elements include the quantities of the following types of materials: paper/cardboard, plastic, wood, metal, glass, and others. They are extracted from the built relational database and subsequently processed and summarized. In this regard, relevant criteria (rules) are formed and applied and certain variables are calculated. In addition, analysis of variance (Anova) and Tukey’s test are also used for these data. The results show that one of the materials (paper/cardboard) in 2010–2018 has relatively higher quantities compared to the rest materials. A similar situation occurs for the element plastic, in 2019–2023. The calculated relative shares of the respective quantities of packaging materials show that more than half of them in the market are made of paper/cardboard and plastic. Some dynamic changes are observed in the quantities for the materials metal and wood. The indicator values for the other materials are significantly lower than the rest. The developed algorithm can be applied to study other time series data in fields such as ecology, finance, etc. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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8 pages, 1683 KB

Open AccessProceeding Paper

Investigation of Technological System Stability During Side Milling

by Iliya Chetrokov, Sabi Sabev and Plamen Kasabov

Eng. Proc. 2025, 100(1), 24; https://doi.org/10.3390/engproc2025100024 - 9 Jul 2025

Viewed by 554

Abstract

This study analyzes technological system stability during side milling by evaluating the influence of two critical parameters: the radial depth of cut (A_e) and feed per tooth (f_z). The experiment was conducted on prismatic samples with stepped geometries to [...] Read more.

This study analyzes technological system stability during side milling by evaluating the influence of two critical parameters: the radial depth of cut (A_e) and feed per tooth (f_z). The experiment was conducted on prismatic samples with stepped geometries to measure deformation at various levels of Ae and f. Regression analysis showed a significant influence of both factors on deformation, with Ae having a stronger effect. The model explains a high level of the variance, confirming the reliability of the experimental data. The results provide guidance for optimizing parameters to improve stability and reduce dimensional deviations. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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10 pages, 1971 KB

Open AccessProceeding Paper

An Experimental Evaluation of Latency-Aware Scheduling for Distributed Kubernetes Clusters

by Radoslav Furnadzhiev

Eng. Proc. 2025, 100(1), 25; https://doi.org/10.3390/engproc2025100025 - 9 Jul 2025

Cited by 2 | Viewed by 2340

Abstract

Kubernetes clusters are deployed across data centers for geo-redundancy and low-latency access, resulting in new challenges in scheduling workloads optimally. This paper presents a practical evaluation of network-aware scheduling in a distributed Kubernetes cluster that spans multiple network zones. A custom scheduling plugin [...] Read more.

Kubernetes clusters are deployed across data centers for geo-redundancy and low-latency access, resulting in new challenges in scheduling workloads optimally. This paper presents a practical evaluation of network-aware scheduling in a distributed Kubernetes cluster that spans multiple network zones. A custom scheduling plugin is implemented within the scheduling framework to incorporate real-time network telemetry (inter-node ping latency) into pod placement decisions. The assessment methodology combines a custom scheduler plugin, realistic network latency measurements, and representative distributed benchmarks to assess the impact of scheduling on traffic patterns. The results provide strong empirical confirmation of the findings previously established through simulation, offering a validated path forward to integrate not only network metrics, but also other performance-critical metrics such as energy efficiency, hardware utilization, and fault tolerance. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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9 pages, 1693 KB

Open AccessProceeding Paper

Methodology for the Design and Verification of a Securing Structure for Transporting Cylindrical Rollers on Load Bogies

by Plamen Kasabov and Marian Kalestrov

Eng. Proc. 2025, 100(1), 26; https://doi.org/10.3390/engproc2025100026 - 10 Jul 2025

Viewed by 554

Abstract

The safe transport of cylindrical loads such as metal, paper, or polymer rollers requires specialized securing structures that address the complex dynamic forces encountered during rail movement. This paper presents a structured methodology for the design and verification of such securing systems, combining [...] Read more.

The safe transport of cylindrical loads such as metal, paper, or polymer rollers requires specialized securing structures that address the complex dynamic forces encountered during rail movement. This paper presents a structured methodology for the design and verification of such securing systems, combining theoretical analysis, standardized load models, and numerical simulations. The method includes load calculations based on EN 12195-1:2010, EN 15551, and Eurocode 1, and validation through finite element modeling in Ansys Workbench. The proposed structure ensures stability under static and dynamic loads, including acceleration, braking, turning, and wind forces, while optimizing wagon space utilization. Simulation results confirm that the design meets strength and safety criteria without exceeding material stress limits, offering a reliable solution for the secure transport of cylindrical rollers. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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8 pages, 869 KB

Open AccessProceeding Paper

Research on and Analysis of Brake Fluid Impact on Brake System Performance

by Georgi Mladenov, Nikola Kuzmanov and Vladimir Hristov

Eng. Proc. 2025, 100(1), 27; https://doi.org/10.3390/engproc2025100027 - 10 Jul 2025

Cited by 2 | Viewed by 3124

Abstract

The present study focuses on the influence of brake fluid on the efficiency of a braking system. Consecutive tests were conducted on the brake discs of a laboratory vehicle heated to approximately 400 °C, and the temperature of the brake fluid was measured. [...] Read more.

The present study focuses on the influence of brake fluid on the efficiency of a braking system. Consecutive tests were conducted on the brake discs of a laboratory vehicle heated to approximately 400 °C, and the temperature of the brake fluid was measured. The boiling points of the brake fluid in the brake system of the test vehicle were also measured and compared with other brake fluids of different brands but identical specifications. The brake fluids tested were both new brake fluids stored in an unopened state and brake fluids that had been opened for more than a year. This was intended to determine which of the elements has the most critical effect on the braking properties of the brake system. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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8 pages, 1503 KB

Open AccessProceeding Paper

A Wind Tunnel Study of the Aerodynamic Characteristics of Wings with Arc-Shaped Wingtips

by Stanimir Penchev and Hristian Panayotov

Eng. Proc. 2025, 100(1), 28; https://doi.org/10.3390/engproc2025100028 - 11 Jul 2025

Viewed by 1981

Abstract

Wingtip devices like winglets and other types have been created to improve the aerodynamic efficiency of aircraft based on minimizing the induced drag of tip vortices. This study aims to investigate the aerodynamic characteristics of these devices at low Reynolds numbers. In the [...] Read more.

Wingtip devices like winglets and other types have been created to improve the aerodynamic efficiency of aircraft based on minimizing the induced drag of tip vortices. This study aims to investigate the aerodynamic characteristics of these devices at low Reynolds numbers. In the present study, the models of a basic non-swept tapered wing and a wing with arc-shaped wingtips are examined. For this purpose, the basic model is equipped with replaceable tips with different geometries. The measurements are performed in a low-speed wind tunnel at a Reynolds number of around 100,000. The analysis of the collected data shows that the best aerodynamic characteristics have a configuration with a 45-degree dihedral angle at the tips of the wing. These results can be used in the conceptual design of small unmanned aerial vehicles (UAVs) to improve their performance in terms of range and endurance. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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8 pages, 2051 KB

Open AccessProceeding Paper

Predicting Traffic Load Data: ARIMA and SARIMA Comparison

by Todor Peychinov, Adeliya Karaivanova and Teodora Mecheva

Eng. Proc. 2025, 100(1), 29; https://doi.org/10.3390/engproc2025100029 - 11 Jul 2025

Cited by 1 | Viewed by 1304

Abstract

The article presents comparison of two statistical methods of data prediction over transport datasets. Autoregressive integrated moving average and its seasonal modification—seasonal autoregressive integrated moving average—are often applied in timeseries data. In current article their effectiveness is assessed using transport data. The data [...] Read more.

The article presents comparison of two statistical methods of data prediction over transport datasets. Autoregressive integrated moving average and its seasonal modification—seasonal autoregressive integrated moving average—are often applied in timeseries data. In current article their effectiveness is assessed using transport data. The data are acquired from data surveillance traffic system of Technical University of Sofia, branch Plovdiv. The conducted experiment encompasses STL transformation, ADF and KPSS stationarity tests, analysis of ACF and PACF, and comparison of different ARIMA and SARIMA configurations. Comparative analysis of MAE, MAPE, and RMSE confirms that ARIMA outperforms SARIMA in current datasets. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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9 pages, 428 KB

Open AccessProceeding Paper

Sensors and Sensing Methods for Early Detection of Life-Threatening Sudden Illnesses in Motor Vehicles Drivers

by Hristo Radev and Galidiya Petrova

Eng. Proc. 2025, 100(1), 30; https://doi.org/10.3390/engproc2025100030 - 11 Jul 2025

Viewed by 918

Abstract

Due to the increasing number of vehicles and the aging population, the vulnerability to sudden medical emergencies among drivers is a growing problem. Events such as heart attack, stroke, and loss of consciousness can occur without warning and endanger everyone on the road. [...] Read more.

Due to the increasing number of vehicles and the aging population, the vulnerability to sudden medical emergencies among drivers is a growing problem. Events such as heart attack, stroke, and loss of consciousness can occur without warning and endanger everyone on the road. Modern vehicles, equipped with electronic systems, can support real-time driver’s health monitoring through early detection technologies. The existing Driver Monitoring Systems (DMS) in our cars assess behavioral states such as drowsiness and distraction. In the future, DMS will include biometric sensors to monitor vital signs such as heart rate and respiration. By finding predictors of sudden illnesses (SI), such a system will provide valuable time for the driver to react before the strike of a medical event. In this paper, we present our vision for DMS operation with physiological monitoring capabilities. A brief overview of sensor’s types and their locations in the vehicle interior used in the research studies for monitoring the corresponding physiological parameters is presented. A comparative analysis of the advantages and disadvantages of the sensing methods used for physiological monitoring of the driver in real driving scenarios is made. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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12 pages, 2175 KB

Open AccessProceeding Paper

A Performance Comparison of Shortest Path Algorithms in Directed Graphs

by Fatima Sapundzhi, Kristiyan Danev, Antonina Ivanova, Metodi Popstoilov and Slavi Georgiev

Eng. Proc. 2025, 100(1), 31; https://doi.org/10.3390/engproc2025100031 - 11 Jul 2025

Cited by 4 | Viewed by 5709

Abstract

This study examines the performance characteristics of four commonly used short-path algorithms, including Dijkstra, Bellman–Ford, Floyd–Warshall, and Dantzig, on randomly generated directed graphs. We analyze theoretical computational complexity and empirical execution time using a custom-built testing framework. The experimental results demonstrate significant performance [...] Read more.

This study examines the performance characteristics of four commonly used short-path algorithms, including Dijkstra, Bellman–Ford, Floyd–Warshall, and Dantzig, on randomly generated directed graphs. We analyze theoretical computational complexity and empirical execution time using a custom-built testing framework. The experimental results demonstrate significant performance differences across varying graph densities and sizes, with Dijkstra’s algorithm showing superior performance for sparse graphs while Floyd–Warshall and Dantzig provide more consistent performance for dense graphs. Time complexity analysis confirms the theoretical expectations: Dijkstra’s algorithm performs best on sparse graphs with O (E + V log V) complexity, Bellman–Ford shows O (V · E) complexity suitable for graphs with negative edges, while Floyd–Warshall and Dantzig both demonstrate O(V³) complexity that becomes efficient for dense graphs. This research provides practical insights for algorithm selection based on specific graph properties, guiding developers and researchers in choosing the most efficient algorithm for their particular graph structure requirements. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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12 pages, 2700 KB

Open AccessProceeding Paper

Implementation of Cored Wire Treatment Technology in Nodular Cast Iron Foundries

by Gergana Buchkova

Eng. Proc. 2025, 100(1), 32; https://doi.org/10.3390/engproc2025100032 - 11 Jul 2025

Viewed by 1842

Abstract

Nodular cast iron is one of the most widely used materials in the machine building industry. The main reasons for this are its strength, elongation, and competitive price compared to other steels and metals. The possibility to have a high strength and elongation [...] Read more.

Nodular cast iron is one of the most widely used materials in the machine building industry. The main reasons for this are its strength, elongation, and competitive price compared to other steels and metals. The possibility to have a high strength and elongation together is thanks to the spheroidal shape of the graphite inserts in the metal structure of the iron. To exploit these advantages, special treatments such as adding magnesium are used after the melting process but before pouring the metal in the casting mold. Classic technology is called tundish/sandwich technology when ferrosiliconmagnesium alloy in bulk is placed at the bottom of a ladle before filling it with liquid cast iron. In the present article, an alternative technology will be presented where a fesimg alloy is filled in a steel wire and inserted automatically into a ladle. The advantages of this technology will be described in detail. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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13 pages, 2392 KB

Open AccessProceeding Paper

A Numerical Parametric Study of the Dynamic Factor in the Rope of a DC-Motor-Driven Hoisting Mechanism

by Rosen Mitrev, Venelin Jivkov and Nikolay Nikolov

Eng. Proc. 2025, 100(1), 33; https://doi.org/10.3390/engproc2025100033 - 11 Jul 2025

Viewed by 962

Abstract

This paper presents a numerical parametric study of a dynamic lumped-parameter model of a hoisting mechanism driven by a DC electric motor. The analysis focuses on two operating scenarios: hoisting with an initially tight rope and hoisting with an initially slack rope. The [...] Read more.

This paper presents a numerical parametric study of a dynamic lumped-parameter model of a hoisting mechanism driven by a DC electric motor. The analysis focuses on two operating scenarios: hoisting with an initially tight rope and hoisting with an initially slack rope. The model considers the inertial, elastic, and damping characteristics of the mechanical system, as well as the motor’s dynamic behavior. Systematic simulations are used to evaluate the influence of key design parameters on the rope’s dynamic factor. Sensitivity analysis is carried out by varying each parameter within a ±20% range, and Monte Carlo simulations are employed to compute Pearson correlation coefficients and perform multiple linear regression. The results indicate that the slack rope scenario produces significantly higher peak dynamic loads than those observed in the tight rope scenario, emphasizing its importance for structural sizing and safety. The findings enhance our understanding of parameter influence and support more robust hoisting system design in transient conditions. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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9 pages, 2222 KB

Open AccessProceeding Paper

Research and Analysis of the Real-Time Interaction Between Performance and Smoke Emission of a Diesel Vehicle

by Iliyan Damyanov, Rosen Miletiev and Tsvetan Ivanov Valkovski

Eng. Proc. 2025, 100(1), 34; https://doi.org/10.3390/engproc2025100034 - 14 Jul 2025

Cited by 1 | Viewed by 1221

Abstract

In recent decades, environmental requirements for reducing the toxic components emitted from vehicle exhausts have decreased drastically. Technologies for after-treatment of diesel vehicle emissions are being improved continuously in order to meet increasingly stringent regulations. Passenger cars are a significant source of air [...] Read more.

In recent decades, environmental requirements for reducing the toxic components emitted from vehicle exhausts have decreased drastically. Technologies for after-treatment of diesel vehicle emissions are being improved continuously in order to meet increasingly stringent regulations. Passenger cars are a significant source of air pollution, especially in urban areas. The EU has decided to phase out internal combustion engines. Stricter Real Driving Emissions (RDE) testing procedures have also been introduced, aiming to assess the emissions of nitrogen oxides (NO_x) and particle number (PN). The present work investigates the interaction between performance and smoke emissions of a diesel vehicle on a pre-established route in an urban environment with an everyday (normal) driving style. The results showed that when the vehicle is technically sound and meets its technical specifications, smoke emissions are within normal limits. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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10 pages, 1194 KB

Open AccessProceeding Paper

Wind Tunnel Investigation of Wake Characteristics of a Wing with Winglets

by Stanimir Penchev, Hristian Panayotov and Martin Zikyamov

Eng. Proc. 2025, 100(1), 35; https://doi.org/10.3390/engproc2025100035 - 14 Jul 2025

Viewed by 947

Abstract

Aircraft performance metrics such as range and endurance are highly dependent on induced and vortex drag. There is a close relationship between wake structure and aerodynamic performance. In the present paper, the velocity field behind the model of a wing with winglet is [...] Read more.

Aircraft performance metrics such as range and endurance are highly dependent on induced and vortex drag. There is a close relationship between wake structure and aerodynamic performance. In the present paper, the velocity field behind the model of a wing with winglet is studied. The methodology and equipment for study in a low-speed wind tunnel ULAK–1 are presented. The pressure field was obtained using a five-hole pressure probe, which was positioned in a cross plane at 300 mm behind the wing trailing edge. The acquired experimental data are used to calculate the cross flow velocity and vorticity fields at an angle of attack of 6 degrees—around the maximum lift-to-drag ratio. The results are compared to the data of a model with planar wing. During the subsequent processing, coefficients of lift and induced drag can be obtained. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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9 pages, 654 KB

Open AccessProceeding Paper

Machine Learning-Powered Agents for Optimized Product Management in Performance Max Campaigns

by Veselka Petrova-Dimitrova

Eng. Proc. 2025, 100(1), 36; https://doi.org/10.3390/engproc2025100036 - 11 Jul 2025

Viewed by 1135

Abstract

Digital advertising is evolving rapidly with the integration of machine learning algorithms, increasingly used for real-time decisions and campaign optimization. This article presents the use of intelligent agents to enhance the effectiveness of Performance Max campaigns. Since campaign-level settings alone are insufficient for [...] Read more.

Digital advertising is evolving rapidly with the integration of machine learning algorithms, increasingly used for real-time decisions and campaign optimization. This article presents the use of intelligent agents to enhance the effectiveness of Performance Max campaigns. Since campaign-level settings alone are insufficient for detailed product-level optimization, two machine learning-based agents were developed: one to detect anomalies in product performance, and another to reallocate products between campaigns based on performance. The first agent analyzes products’ daily metrics and triggers alerts for unusual deviations. The second agent autonomously moves products between campaigns based on their performance to maximize the results, as well as improve the performance in terms of visibility and return on investment of the moved products. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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22 pages, 893 KB

Open AccessProceeding Paper

Research and Analysis of Traffic Intensity on a Street with High Traffic Load: Case Study of the City of Sofia

by Durhan Saliev, Georgi Mladenov and Plamen Petkov

Eng. Proc. 2025, 100(1), 37; https://doi.org/10.3390/engproc2025100037 - 11 Jul 2025

Cited by 1 | Viewed by 1681

Abstract

The study of traffic parameters in cities is the basis for making adequate decisions related to the organization and regulation of traffic. This publication presents a study of one of the main parameters of transport flows, namely, its intensity. The study covers one [...] Read more.

The study of traffic parameters in cities is the basis for making adequate decisions related to the organization and regulation of traffic. This publication presents a study of one of the main parameters of transport flows, namely, its intensity. The study covers one of the busiest streets in the city of Sofia, which is part of the radial connection in the radial circular street network of the city, for the evening peak period of the day. Data analysis presents the influence of the intensity of transport flows at the intersections, which are formed by the intersection with other streets, on the load of the studied street. The share of the load of each transport flow at the individual intersections on the total load of the studied section was recorded for the subsequent assessment of the existing traffic management. The results have been provided to the relevant directorates in the structure of Sofia Municipality for information and use. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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11 pages, 3933 KB

Open AccessProceeding Paper

Thermal and Structural Analysis of Gasoline Engine Piston at Different Boost Pressures

by Krasimir Ambarev and Stiliyana Taneva

Eng. Proc. 2025, 100(1), 38; https://doi.org/10.3390/engproc2025100038 - 14 Jul 2025

Cited by 2 | Viewed by 2749

Abstract

The piston, as one of the main components of the crankshaft mechanism, is subjected to significant mechanical and thermal loads. The mechanical properties of the alloy from which it is made and the technology of its manufacture are related to the maximum allowable [...] Read more.

The piston, as one of the main components of the crankshaft mechanism, is subjected to significant mechanical and thermal loads. The mechanical properties of the alloy from which it is made and the technology of its manufacture are related to the maximum allowable value of the combustion pressure. The purpose of this paper is to determine the maximum value of the boost pressure of an existing gasoline engine, without causing damage to its piston. To achieve this goal, the stress and strain state of the piston was determined using finite element analysis (FEA) with consideration of the influence of temperature at different values of the boost (intake) pressure. The temperature distribution of the piston was determined using transient thermal analysis. The analyses were performed using SolidWorks Simulation. The obtained results were compared and analyzed. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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19 pages, 1680 KB

Open AccessProceeding Paper

Engineering and Environmental Analysis of Additive Manufacturing in the Food Industry

by Valentina Nikolova-Alexieva, Katina Valeva, Margarita Terziyska and Hristian Panayotov

Eng. Proc. 2025, 100(1), 39; https://doi.org/10.3390/engproc2025100039 - 14 Jul 2025

Cited by 1 | Viewed by 1283

Abstract

In the context of increasing demands for sustainability and individualization in the food industry, additive manufacturing (AM) represents a promising technology with the potential to transform manufacturing processes. This study proposes an integrated engineering–environmental analysis of the applicability of additive manufacturing in the [...] Read more.

In the context of increasing demands for sustainability and individualization in the food industry, additive manufacturing (AM) represents a promising technology with the potential to transform manufacturing processes. This study proposes an integrated engineering–environmental analysis of the applicability of additive manufacturing in the food sector through a combined methodological framework, including techno-economic assessment (TEA) and life cycle assessment (LCA). This article provides a structured methodology and practical engineering models for assessing additive manufacturing. These can support strategic decision-making by industrial manufacturers and research communities aiming for sustainable and flexible manufacturing systems. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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16 pages, 2354 KB

Open AccessProceeding Paper

Design and Implementation of a Passive Optical Network for a Small Town

by Fatima Sapundzhi, Boyko Zarev, Slavi Georgiev, Snezhinka Zaharieva, Metodi Popstoilov and Meglena Lazarova

Eng. Proc. 2025, 100(1), 40; https://doi.org/10.3390/engproc2025100040 - 15 Jul 2025

Cited by 1 | Viewed by 3126

Abstract

The increasing demand for high-speed internet and advanced digital services necessitates the deployment of robust and scalable broadband infrastructure, particularly in smaller urban and rural areas. This paper presents the design and implementation of a passive optical network (PON) based on a gigabit-capable [...] Read more.

The increasing demand for high-speed internet and advanced digital services necessitates the deployment of robust and scalable broadband infrastructure, particularly in smaller urban and rural areas. This paper presents the design and implementation of a passive optical network (PON) based on a gigabit-capable passive optical network (GPON) standard to deliver fiber-to-the-home (FTTH) services in a small-town setting. The proposed solution prioritizes cost-effectiveness, scalability, and minimal energy consumption by leveraging passive splitters and unpowered network elements. We detail the topology planning, splitter architecture, installation practices, and technical specifications that ensure efficient signal distribution and future network expansion. The results demonstrate the successful implementation of an optical access infrastructure that supports high-speed internet, Internet Protocol television (IPTV), and voice services while maintaining flexibility for diverse urban layouts and housing types. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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7 pages, 482 KB

Open AccessProceeding Paper

Parameters Characterizing the Performance of Automotive Electronic Control Systems on Petrol Engine Emissions

by Hristo Konakchiev and Evgeni Dimitrov

Eng. Proc. 2025, 100(1), 41; https://doi.org/10.3390/engproc2025100041 - 15 Jul 2025

Cited by 2 | Viewed by 965

Abstract

It is evident that a novel engineering solution is required in order to elevate a greater number of polluting cars into a higher category. There appears to be a paucity of direct interest in upgrading Euro 1, 2, 3, 4, and 5 vehicles [...] Read more.

It is evident that a novel engineering solution is required in order to elevate a greater number of polluting cars into a higher category. There appears to be a paucity of direct interest in upgrading Euro 1, 2, 3, 4, and 5 vehicles to the highest possible level, primarily through software modifications of the parameters determining the performance of the internal combustion engine (ICE). The potential for advancement in this area is evidenced by the presence of systems that enhance environmental efficiency, even in Euro 2 vehicles. These include exhaust gas recirculation, catalytic converter, lambda sensor, electronic control fuel injection, and ignition timing. It is precisely these vehicles that are subject to optimization, a process which would allow the maximum service life of otherwise more reliable but older vehicles to be exploited. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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9 pages, 2291 KB

Open AccessProceeding Paper

A Comparative Study of Vibrations in Front Suspension Components Using Bushings Made from Different Materials

by Krasimir Ambarev and Stiliyana Taneva

Eng. Proc. 2025, 100(1), 42; https://doi.org/10.3390/engproc2025100042 - 15 Jul 2025

Cited by 1 | Viewed by 1518

Abstract

The design of the suspension system affects handling and stability, vibrations of the steered wheels, vehicle ride comfort, and tyre tread wear. One of the most important vibration parameters is acceleration; high acceleration values can have an adverse effect on both the driver [...] Read more.

The design of the suspension system affects handling and stability, vibrations of the steered wheels, vehicle ride comfort, and tyre tread wear. One of the most important vibration parameters is acceleration; high acceleration values can have an adverse effect on both the driver and passengers, as well as on the components of the vehicle’s suspension and handling. This paper presents the results of the effects of acceleration on the components of a front-independent MacPherson suspension system. Data on the accelerations were obtained from theoretical and experimental studies. A simulation study was conducted, taking into account the elastic and damping characteristics of the elastic components. The experimental study was conducted under laboratory conditions by using a suspension tester, BEISSBARTH, and a measuring system developed with LabVIEW 2021 SP1 and MATLAB R2022b software. The experiments were conducted with different tyre pressures and by using bushings made from different materials. The experimental tests were conducted with two rubber bushings within the mounting of the arm, as well as a rubber bushing and a polyurethane bushing. The experimental results were compared and analyzed. Two theoretical models were considered: one is a mathematical model, and the other is a simulation model which uses the finite element method. Numerical dynamic analysis of the suspension was performed using the SolidWorks 2023. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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9 pages, 2918 KB

Open AccessProceeding Paper

A Study on a Phase-Shift Controlled ZVS DC-DC Converter with a Synchronous Rectifier

by Tsvetana Grigorova, Georgi Bodurov and Mihail Dobrolitsky

Eng. Proc. 2025, 100(1), 43; https://doi.org/10.3390/engproc2025100043 - 15 Jul 2025

Cited by 1 | Viewed by 1145

Abstract

The paper presents a study on a phase-shift controlled zero-voltage switching (ZVS) full-bridge DC-DC converter employing synchronous rectification using the LTC3722-1 controller. This analysis aimed to examine the impact of additional commutating inductance on the establishment of ZVS conditions, the precision of switching [...] Read more.

The paper presents a study on a phase-shift controlled zero-voltage switching (ZVS) full-bridge DC-DC converter employing synchronous rectification using the LTC3722-1 controller. This analysis aimed to examine the impact of additional commutating inductance on the establishment of ZVS conditions, the precision of switching control, and the dynamic interaction between ZVS performance and varying load conditions. The validity of this approach is achieved by presenting both simulation and experimental results, which illustrate its application in practical applications. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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12 pages, 450 KB

Open AccessProceeding Paper

Methodology for Automatic Information Extraction and Summary Generation from Online Sources for Project Funding

by Mariya Zhekova

Eng. Proc. 2025, 100(1), 44; https://doi.org/10.3390/engproc2025100044 - 11 Jul 2025

Viewed by 1928

Abstract

The summarized content of one or more extensive text documents helps users extract only the most important key information, instead of reviewing and reading hundreds of pages of text. This study uses extractive and abstractive mechanisms to automatically extract and summarize information retrieved [...] Read more.

The summarized content of one or more extensive text documents helps users extract only the most important key information, instead of reviewing and reading hundreds of pages of text. This study uses extractive and abstractive mechanisms to automatically extract and summarize information retrieved from various web documents on the same topic. The research aims to develop a methodology for designing and developing an information system for pre- and post-processing natural language obtained through web content search and web scraping, and for the automatic generation of a summary of the retrieved text. The research outlines two subtasks. As a first step, the system is designed to collect and process up-to-date information based on specific criteria from diverse web resources related to project funding, initiated by various organizations such as startups, sustainable companies, municipalities, government bodies, schools, the NGO sector, and others. As a second step, the collected extensive textual information about current projects and programs, which is typically intended for financial professionals, is to be summarized into a shorter version and transformed into a suitable format for a wide range of non-specialist users. The automated AI software tool, which will be developed using the proposed methodology, will be able to crawl and read project funding information from various web documents, select, process, and prepare a shortened version containing only the most important key information for its clients. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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6 pages, 326 KB

Open AccessProceeding Paper

Traffic Flow Model for Coordinated Traffic Light Systems

by Iliyan Andreev, Durhan Saliev and Iliyan Damyanov

Eng. Proc. 2025, 100(1), 45; https://doi.org/10.3390/engproc2025100045 - 17 Jul 2025

Cited by 2 | Viewed by 991

Abstract

Traffic in large cities is increasing due to continuous urbanization, the construction of new housing complexes and the accompanying new street network. The growth of cities creates prerequisites for increasing the intensity of transport, pedestrian, and bicycle flows, especially during peak periods. To [...] Read more.

Traffic in large cities is increasing due to continuous urbanization, the construction of new housing complexes and the accompanying new street network. The growth of cities creates prerequisites for increasing the intensity of transport, pedestrian, and bicycle flows, especially during peak periods. To improve the conditions in which traffic flows, it is necessary to introduce an effective method for reducing delays that arise at intersections, especially those regulated by traffic light systems. One of the possible approaches to this is to coordinate the operation of traffic light systems. The main thing in this is to determine relatively accurate times for the movement of individual flows, for which adequate traffic models are needed. This article presents a model of the movement of transport flows when starting from the first intersection in a coordinated mode of operation of traffic light systems. This is of particular importance when determining the times of individual signals and, above all, has an impact on the moment for switching on the permitting signal at the next intersection. The presented model aims to provide an opportunity to determine accurate times of passage of vehicles through consecutive intersections that operate in a coordinated mode of traffic light systems. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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10 pages, 3334 KB

Open AccessProceeding Paper

A Study of the Microstructure of Non-Standardised Alternative Piston Aluminium–Silicon Alloys Subjected to Various Modifications: The Influence of Modification Treatments on the Microstructure and Properties of These Alloys

by Desislava Dimova, Valyo Nikolov, Bozhana Chuchulska, Veselin Tsonev and Nadezhda Geshanova

Eng. Proc. 2025, 100(1), 46; https://doi.org/10.3390/engproc2025100046 - 16 Jul 2025

Cited by 1 | Viewed by 1062

Abstract

The present study examines the structure, properties and use of complex-alloyed hypereutectic aluminium-silicon alloys, emphasising the control of the morphology of primary silicon via treatment with various modifiers as well as their effects on its shape and distribution. Furthermore, this study reviews the [...] Read more.

The present study examines the structure, properties and use of complex-alloyed hypereutectic aluminium-silicon alloys, emphasising the control of the morphology of primary silicon via treatment with various modifiers as well as their effects on its shape and distribution. Furthermore, this study reviews the experimental work related to the simultaneous modification of primary and eutectic silicon, which leads to the conclusion that favourable results can be obtained by complex modification treatment involving first- and second-type modifiers. After being cast, the AlSi18Cu3CrMn and AlSi18Cu5Mg non-standardised piston alloys are subjected to T6 heat treatment intended to enhance their mechanical performance, harnessing the full potential of the alloying elements. A microstructural analysis of the shape and distribution of both primary and eutectic silicon crystals following heat treatment was employed to determine their microhardness. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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9 pages, 1161 KB

Open AccessProceeding Paper

An Approach for the Accelerated Heat Aging of Test Specimens Produced Using 3D Additive Materials

by Miglena Paneva and Peter Panev

Eng. Proc. 2025, 100(1), 47; https://doi.org/10.3390/engproc2025100047 - 18 Jul 2025

Cited by 2 | Viewed by 1435

Abstract

In this work, an approach has been developed for the accelerated aging of test specimens with an electrical furnace for tensile strength and hardness testing, manufactured using a 3D Fused Deposition Modeling (FDM) printer. A detailed study of the climatic conditions and temperature [...] Read more.

In this work, an approach has been developed for the accelerated aging of test specimens with an electrical furnace for tensile strength and hardness testing, manufactured using a 3D Fused Deposition Modeling (FDM) printer. A detailed study of the climatic conditions and temperature amplitudes of the city of Sofia, Bulgaria, over a period of one calendar year was conducted. The ASTM D3045 standard was used, and numerical expressions were compiled, which guided the authors in determining the period and temperature of heating. Eight types of FDM 3D printing materials with different properties and characteristics were used in this study. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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11 pages, 1452 KB

Open AccessProceeding Paper

Event-Driven Data Orchestration: A Modular Approach for High-Volume Real-Time Processing

by Stanislav Dakov and Megi Dakova

Eng. Proc. 2025, 100(1), 48; https://doi.org/10.3390/engproc2025100048 - 18 Jul 2025

Viewed by 1038

Abstract

This article presents a model for orchestrating data extraction, processing, and storage, addressing the challenges posed by diverse data sources and increasing data volumes. The proposed model includes three primary components: data production, data transfer, and data consumption and storage. Key architectures for [...] Read more.

This article presents a model for orchestrating data extraction, processing, and storage, addressing the challenges posed by diverse data sources and increasing data volumes. The proposed model includes three primary components: data production, data transfer, and data consumption and storage. Key architectures for data production are explored, such as modular designs and distributed processes, each with advantages and limitations regarding scalability, fault tolerance, and resource efficiency. A buffering module is introduced to enable temporary data storage, ensuring resilience and asynchronous processing. The data consumption module focuses on transforming and storing data in data warehouses while providing options for parallel and unified processing architectures to enhance efficiency. Additionally, a notification module demonstrates real-time alerts based on specific data events, integrating seamlessly with messaging platforms like Telegram. The model is designed to ensure adaptability, scalability, and robustness for modern data-driven applications, making it a versatile solution for effective data flow management. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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13 pages, 2619 KB

Open AccessProceeding Paper

Planning Resources by Model Predictive Control

by Krasimira Stoilova, Todor Stoilov and Galia Angelova

Eng. Proc. 2025, 100(1), 49; https://doi.org/10.3390/engproc2025100049 - 18 Jul 2025

Cited by 1 | Viewed by 1089

Abstract

The effective functioning of an organization is directly related to properly planning the necessary resources. The purpose of the study is to propose a solution for appropriate resource planning to help the decision-maker. An applied approach integrates forecasting using linear autoregressive analysis, optimal [...] Read more.

The effective functioning of an organization is directly related to properly planning the necessary resources. The purpose of the study is to propose a solution for appropriate resource planning to help the decision-maker. An applied approach integrates forecasting using linear autoregressive analysis, optimal determination of regression coefficients as solutions to optimization problems with an embedded least squares method and sliding shift procedure for a new start of historical data. Two linear predictive models were created and validated with real data in a simulation environment under two scenarios. Comparisons were made with the real data, as well as between the two models. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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9 pages, 1551 KB

Open AccessProceeding Paper

Tensile Testing of Polymer Material Specimens Obtained by Fused Deposition Modeling

by Miglena Paneva, Peter Panev and Veselin Tsonev

Eng. Proc. 2025, 100(1), 50; https://doi.org/10.3390/engproc2025100050 - 18 Jul 2025

Cited by 2 | Viewed by 1982

Abstract

In this work, a comparative analysis of polymer test specimens from different types of filaments, manufactured using FDM technology, was performed. A tensile strength test was executed on test specimens after 3D additive printing, made from different groups of materials—PLA, PLA Wood, PETG, [...] Read more.

In this work, a comparative analysis of polymer test specimens from different types of filaments, manufactured using FDM technology, was performed. A tensile strength test was executed on test specimens after 3D additive printing, made from different groups of materials—PLA, PLA Wood, PETG, PC, PA6, ASA, CPE HG100 and FilaFlex SEBS. Test specimens from the same materials were subjected to accelerated aging, after which they were tested again for tensile strength. The results of all tests were analyzed and compared. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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8 pages, 1746 KB

Open AccessProceeding Paper

Application of a Three-Dimensional Model in the Analysis of a Traffic Accident Involving a Motorcycle and a Pedestrian

by Milena Savova-Mratsenkova and Borislav Vasilovski

Eng. Proc. 2025, 100(1), 51; https://doi.org/10.3390/engproc2025100051 - 21 Jul 2025

Viewed by 809

Abstract

In this research work, the authors propose an approach for analyzing a traffic accident involving a motorcycle and a pedestrian. The study was conducted under the condition that there are objects in the accident area that limit the visibility of the participants. For [...] Read more.

In this research work, the authors propose an approach for analyzing a traffic accident involving a motorcycle and a pedestrian. The study was conducted under the condition that there are objects in the accident area that limit the visibility of the participants. For this purpose, a three-dimensional simulation model was developed to determine the relative positions of the pedestrian and the motorcycle-driver system at discrete moments, examining the period of time from the moment the pedestrian steps onto the roadway to the moment of contact between the participants. Data from a real traffic accident were used. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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14 pages, 5148 KB

Open AccessProceeding Paper

Numerical Modeling and Analysis of Fatigue Failure in 42CrMo4 Steel Pivot Bolts at Different Heat Treatments

by Ivanka Delova, Tsvetomir Borisov, Yordan Mirchev and Raycho Raychev

Eng. Proc. 2025, 100(1), 52; https://doi.org/10.3390/engproc2025100052 - 17 Jul 2025

Viewed by 988

Abstract

This study presents a numerical model for analyzing fatigue crack growth in 42CrMo4 steel pivot bolts under different heat treatments and service loads. The finite element method (FEM) in the ANSYS Workbench environment (version 2019R1) (SMART Crack Growth), along with algorithms based on [...] Read more.

This study presents a numerical model for analyzing fatigue crack growth in 42CrMo4 steel pivot bolts under different heat treatments and service loads. The finite element method (FEM) in the ANSYS Workbench environment (version 2019R1) (SMART Crack Growth), along with algorithms based on Paris’s law implemented in MATLAB (version R2016a), was used. The results highlight the significant influence of heat treatment on fatigue resistance and serve as a basis for optimizing design parameters and improving the durability of the structural components. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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11 pages, 8000 KB

Open AccessProceeding Paper

A Functional Model Printing Approach Optimized for Cost-Efficiency Using FDM Technology

by Blagovest Bankov, Todor T. Todorov and Georgi Todorov

Eng. Proc. 2025, 100(1), 53; https://doi.org/10.3390/engproc2025100053 - 21 Jul 2025

Viewed by 1249

Abstract

The study focuses on optimizing the Fused Deposition Modeling (FDM) process by implementing a cost-efficient support structure strategy. The main objective is to develop a systematic approach for analyzing structural and technological parameters considering print time, material consumption, and surface quality. The study [...] Read more.

The study focuses on optimizing the Fused Deposition Modeling (FDM) process by implementing a cost-efficient support structure strategy. The main objective is to develop a systematic approach for analyzing structural and technological parameters considering print time, material consumption, and surface quality. The study focus is on manually designed support structures as an alternative to automatic generation, allowing for precise control over print settings. The methodology includes comparative analysis of various support strategies using a Prusa MK3S+ printer under standardized conditions. Statistical and visual evaluations confirm that the designed support structures reduce print time by up to 59 min while maintaining comparable material use and superior surface finish. The findings offer a practical framework for optimizing 3D printing processes, reducing waste, and enhancing efficiency in prototyping and small-batch production. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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6 pages, 927 KB

Open AccessProceeding Paper

Investigation of the Influence of Deposition Temperature and N₂ Flow on the Hardness of TiN Coating

by Chavdar Pashinski

Eng. Proc. 2025, 100(1), 54; https://doi.org/10.3390/engproc2025100054 - 17 Jul 2025

Viewed by 621

Abstract

Although the field of industrial coatings grows rapidly, some classic solutions do not lose their relevance. In this work, the creation and study of a TiN coating are described, taking into account the influence of two important factors in the process—deposition temperature and [...] Read more.

Although the field of industrial coatings grows rapidly, some classic solutions do not lose their relevance. In this work, the creation and study of a TiN coating are described, taking into account the influence of two important factors in the process—deposition temperature and N₂ flow rate. The method shown here could also be applied to other coatings, especially in the initial stage of their development. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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6 pages, 1910 KB

Open AccessProceeding Paper

Design and Construction of an Engine Oil Viscosity Meter with Electronic Control

by Penko Mitev, Atanasi Tashev and Yordan Stoyanov

Eng. Proc. 2025, 100(1), 55; https://doi.org/10.3390/engproc2025100055 - 22 Jul 2025

Cited by 2 | Viewed by 1357

Abstract

This study presents the design and implementation of a novel, sensor-based falling-sphere viscometer specifically tailored for measuring the viscosity of engine oil. The equipment utilizes a metallic sphere and two strategically placed sensors to determine the travel time over a predetermined distance within [...] Read more.

This study presents the design and implementation of a novel, sensor-based falling-sphere viscometer specifically tailored for measuring the viscosity of engine oil. The equipment utilizes a metallic sphere and two strategically placed sensors to determine the travel time over a predetermined distance within an oil-filled tube. By applying fundamental principles of fluid dynamics, including Stokes’ law, the system accurately calculates the dynamic viscosity based on the sphere’s velocity and the oil’s density. Experimental validation at particular temperature demonstrates the device’s sensitivity and reliability, which are critical for assessing oil degradation and engine performance. The simplicity and low cost of the design make it an attractive alternative to conventional, more complex viscometers. Furthermore, the automated data acquisition system reduces human error and enhances reproducibility of results. Overall, the developed instrument shows great promise for both laboratory research and practical maintenance applications in the automotive industry. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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10 pages, 1207 KB

Open AccessProceeding Paper

Generalized Net Model for Analysis of Behavior and Efficiency of Intelligent Virtual Agents in Risky Environment

by Dilyana Budakova, Velyo Vasilev and Lyudmil Dakovski

Eng. Proc. 2025, 100(1), 56; https://doi.org/10.3390/engproc2025100056 - 17 Jul 2025

Viewed by 506

Abstract

In this article, two generalized net models (GNMs) are proposed to study the behavior and effectiveness of intelligent virtual agents (IVA) working in a risky environment under different scenarios and training algorithms. The proposed GNMs allow for the selection of machine learning algorithms [...] Read more.

In this article, two generalized net models (GNMs) are proposed to study the behavior and effectiveness of intelligent virtual agents (IVA) working in a risky environment under different scenarios and training algorithms. The proposed GNMs allow for the selection of machine learning algorithms such as intensity of characteristics Q-learning (InCh-Q), as well as the modification of multi-plan reinforcement learning (RL), proximal policy optimization (PPO), soft actor–critic (SAC), the generative adversarial imitation learning (GAIL) algorithm, and behavioral cloning (CB). The choice of action, the change in priorities, and the achievement of goals by the IVA are studied under different scenarios, such as fire extinguishing, rescue operations, evacuation, patrolling, and training. Transitions in the GNMs represent the scenarios and learning algorithms. The tokens that pass through the GNMs can be the GNMs of the IVA architecture or the IVA memory model, which are enriched with knowledge and experience during the experiments, as the scenarios develop. The proposed GNMs are formally correct and, at the same time, understandable, practically applicable, and convenient for interpretation. Achieving GNMs that meet these requirements is a complex problem. Therefore, issues related to the design and use of GNMs for the reliable modeling and analysis of the behavior and effectiveness of IVAs operating in a dynamic and risky environment are discussed. Some advantages and challenges in using GNMs compared to other classical models used to study IVA behavior are considered. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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16 pages, 1913 KB

Open AccessProceeding Paper

Collaborative Robots as an Engineering Tool for the Transition of the Food Industry to Industry 5.0

by Valentina Nikolova-Alexieva, Katina Valeva, Margarita Terziyska and Nikola Shakev

Eng. Proc. 2025, 100(1), 57; https://doi.org/10.3390/engproc2025100057 - 22 Jul 2025

Cited by 1 | Viewed by 4252

Abstract

The article examines the application of collaborative robots (cobots) as a modern engineering tool for the transformation of the food industry following the principles of Industry 5.0. A conceptual engineering model has been developed that integrates collaborative robots with IoT systems, digital twins, [...] Read more.

The article examines the application of collaborative robots (cobots) as a modern engineering tool for the transformation of the food industry following the principles of Industry 5.0. A conceptual engineering model has been developed that integrates collaborative robots with IoT systems, digital twins, and predictive analytics to increase the flexibility, safety, and sustainability of production processes. The proposed model is validated through a practical case study focused on a yogurt packaging line in the dairy sector, where cobot systems demonstrate a significant improvement in operational efficiency and process safety. A step-by-step strategic roadmap is presented to guide industrial enterprises through the various stages of implementation, from the initial assessment to the full-scale integration of solutions. Additionally, a comparative analysis has been performed between traditional automated systems and the integrated approach with collaborative robots, which highlights the technological, economic, and human-oriented advantages of the latter. The results of the study confirm that collaborative robotics offers an effective and applicable path for transforming the food and beverage industry towards a sustainable, adaptive, and human-centered manufacturing ecosystem characteristic of Industry 5.0. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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8 pages, 2537 KB

Open AccessProceeding Paper

Theoretical and Experimental Research on Centrifugal Casting of Short and Long Castings

by Angel Velikov, Ivan Georgiev, Boyko Krastev and Krum Petrov

Eng. Proc. 2025, 100(1), 58; https://doi.org/10.3390/engproc2025100058 - 28 Jul 2025

Viewed by 1276

Abstract

The technological process of the centrifugal casting of short and long castings is examined during development. The values of the technological parameters at applying heat-resistant coating on the working surface of metal molds were established. With a high-speed camera, the temperature of the [...] Read more.

The technological process of the centrifugal casting of short and long castings is examined during development. The values of the technological parameters at applying heat-resistant coating on the working surface of metal molds were established. With a high-speed camera, the temperature of the free surface during the pouring of the melts was measured. Research experiments were conducted. A mathematical model of the centrifugal casting process with a horizontal axis was created. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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9 pages, 1552 KB

Open AccessProceeding Paper

Kolmogorov–Arnold Networks for System Identification of First- and Second-Order Dynamic Systems

by Lily Chiparova and Vasil Popov

Eng. Proc. 2025, 100(1), 59; https://doi.org/10.3390/engproc2025100059 - 30 Jul 2025

Cited by 3 | Viewed by 1910

Abstract

System identification—originating in the 1950s from statistical theory—has since developed a wealth of algorithms, insights, and practical expertise. We introduce Kolmogorov–Arnold neural networks (KANs) as an interpretable alternative for model discovery. Leveraging KANs’ inherent property to approximate data and interpret it by employing [...] Read more.

System identification—originating in the 1950s from statistical theory—has since developed a wealth of algorithms, insights, and practical expertise. We introduce Kolmogorov–Arnold neural networks (KANs) as an interpretable alternative for model discovery. Leveraging KANs’ inherent property to approximate data and interpret it by employing learnable activation functions and decomposition of multivariate mappings into univariate transforms, we test its ability to recover the step responses of first- and second-order systems both numerically and symbolically. We employ synthetic datasets, both noise-free and with Gaussian noise, and find that KANs can achieve very low RMSE and parameter error with simple architectures. Our results demonstrate that KANs combine ease of implementation with symbolic transparency, positioning them as a compelling bridge between classical identification and modern machine learning. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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10 pages, 3823 KB

Open AccessProceeding Paper

Investigation of Triple-Microcantilever Sensor for Ultra-Low Mass-Sensing Applications

by Luca Banchelli, Vladimir Stavrov, Borislav Ganev, Nikolay Nikolov and Todor Todorov

Eng. Proc. 2025, 100(1), 60; https://doi.org/10.3390/engproc2025100060 - 17 Jul 2025

Cited by 1 | Viewed by 902

Abstract

This paper discusses a new method and sensor for the detection of ultra-low masses, such as those of viruses and biomarkers. The sensor contains three microcantilevers with a common substrate that vibrates. The detection method processes phase-shifted signals from Wheatstone bridges from connected [...] Read more.

This paper discusses a new method and sensor for the detection of ultra-low masses, such as those of viruses and biomarkers. The sensor contains three microcantilevers with a common substrate that vibrates. The detection method processes phase-shifted signals from Wheatstone bridges from connected piezoresistors formed on the vibrating microcantilevers and passive resistors on the rigid substrate. Each microcantilever has a gold pad that can be either active or passive. When a mass is detected, the shape of the amplitude–frequency response changes. The proposed method has high mass sensitivity and can respond up to one minute, which is an important challenge for nanocantilever sensors. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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11 pages, 2935 KB

Open AccessProceeding Paper

Crack Growth Modeling in CT Specimens: The Influence of Heat Treatment and Loading

by Raycho Raychev, Ivanka Delova, Tsvetomir Borisov and Yordan Mirchev

Eng. Proc. 2025, 100(1), 61; https://doi.org/10.3390/engproc2025100061 - 21 Jul 2025

Viewed by 1046

Abstract

This study provides a combined numerical and analytical investigation of fatigue crack growth in compact tension specimens made of 42CrMo4 steel. Through simulations in ANSYS Workbench (SMART Crack Growth module) and numerical modeling in MATLAB, the model is validated by comparing its results [...] Read more.

This study provides a combined numerical and analytical investigation of fatigue crack growth in compact tension specimens made of 42CrMo4 steel. Through simulations in ANSYS Workbench (SMART Crack Growth module) and numerical modeling in MATLAB, the model is validated by comparing its results with the standard ASTM E399 and Paris’ law relationships. The effect of heat treatments and loading on crack growth rate was investigated. The results confirm the model’s applicability in predicting fatigue behavior in the linear–elastic region. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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21 pages, 3033 KB

Open AccessProceeding Paper

Robot Modeling and Control in Digital Twin System

by Denis Chikurtev, Vladimir Ivanov, Simeon Tsvetanov and Kaloyan Yovchev

Eng. Proc. 2025, 100(1), 62; https://doi.org/10.3390/engproc2025100062 - 21 Jul 2025

Cited by 3 | Viewed by 1696

Abstract

This paper presents studies of a digital twin system. A conceptual model of the system is proposed to be used to control an industrial robot and can be integrated into different fields of application such as industry, manufacturing, farming, livestock breeding and others. [...] Read more.

This paper presents studies of a digital twin system. A conceptual model of the system is proposed to be used to control an industrial robot and can be integrated into different fields of application such as industry, manufacturing, farming, livestock breeding and others. On the principle of software engineering, the overall architecture of the system is developed, and its constituent elements are presented in detail. A kinematic analysis of the considered industrial robot is presented. To realize the digital twin, a simulation model of the industrial robot was developed to fully meet the dimensions and kinematic characteristics of the real one. Experiments have been made on the operation of the system so as to compare the movements of the real and simulated robot. The results obtained show almost identical motions both in the end effector of the robots and in the motions of each of the joints. A short methodology for the steps of creating systems using digital twins is presented to assist developers and scientists. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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8 pages, 1542 KB

Open AccessProceeding Paper

Mapless Navigation with Deep Reinforcement Learning in Indoor Environment

by Anastasiya Slavova and Vladimir Hristov

Eng. Proc. 2025, 100(1), 63; https://doi.org/10.3390/engproc2025100063 - 25 Jul 2025

Cited by 1 | Viewed by 2236

Abstract

One of the crucial tasks for autonomous robots is learning to safely navigate through obstacles in real-world environments. An intelligent robot must not only perform the assigned task but also adapt to changes in its environment as quickly as possible. In this work, [...] Read more.

One of the crucial tasks for autonomous robots is learning to safely navigate through obstacles in real-world environments. An intelligent robot must not only perform the assigned task but also adapt to changes in its environment as quickly as possible. In this work, we propose an improved version of the Deep Reinforcement Learning (DRL) Proximal Policy Optimization (PPO) algorithm by modifying a deep neural network of the Actor and Critic. Then we compare the results of our work by comparing them with those of classical PPO. Algorithm testing is conducted in a Flatland simulation environment, which allows for integration with the ROS2 operating environment. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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12 pages, 1486 KB

Open AccessProceeding Paper

Comparative Analysis Between Simulation Using Specialized Software for Photovoltaic Power Plant Design and Real-World Data from a Solar Power Plant

by Mincho Velkov and Stanimir Stefanov

Eng. Proc. 2025, 100(1), 64; https://doi.org/10.3390/engproc2025100064 - 31 Jul 2025

Viewed by 1545

Abstract

This study presents a comparative analysis between simulated results obtained using PVSol Expert software and real operational data from a functioning photovoltaic power plant (PVPP) located in Plovdiv, Bulgaria. The primary objective is to evaluate the accuracy and practical applicability of simulation-based predictions [...] Read more.

This study presents a comparative analysis between simulated results obtained using PVSol Expert software and real operational data from a functioning photovoltaic power plant (PVPP) located in Plovdiv, Bulgaria. The primary objective is to evaluate the accuracy and practical applicability of simulation-based predictions compared to actual system performance under real-world climatic and geographical conditions. The analysis is based on a comprehensive dataset, including generated electricity, solar irradiance levels, ambient temperature, and system losses. These real measurements are systematically compared against a PVSol Expert simulation model constructed using identical input parameters—such as module orientation and tilt, number and type of panels, inverter specifications, and electrical configuration. The results provide insight into the reliability of simulation tools for design verification and performance forecasting in photovoltaic applications. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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13 pages, 733 KB

Open AccessProceeding Paper

AI-Based Assistant for SORA: Approach, Interaction Logic, and Perspectives for Cybersecurity Integration

by Anton Puliyski and Vladimir Serbezov

Eng. Proc. 2025, 100(1), 65; https://doi.org/10.3390/engproc2025100065 - 1 Aug 2025

Viewed by 1699

Abstract

This article presents the design, development, and evaluation of an AI-based assistant tailored to support users in the application of the Specific Operations Risk Assessment (SORA) methodology for unmanned aircraft systems. Built on a customized language model, the assistant was trained using system-level [...] Read more.

This article presents the design, development, and evaluation of an AI-based assistant tailored to support users in the application of the Specific Operations Risk Assessment (SORA) methodology for unmanned aircraft systems. Built on a customized language model, the assistant was trained using system-level instructions with the goal of translating complex regulatory concepts into clear and actionable guidance. The approach combines structured definitions, contextualized examples, constrained response behavior, and references to authoritative sources such as JARUS and EASA. Rather than substituting expert or regulatory roles, the assistant provides process-oriented support, helping users understand and complete the various stages of risk assessment. The model’s effectiveness is illustrated through practical interaction scenarios, demonstrating its value across educational, operational, and advisory use cases, and its potential to contribute to the digital transformation of safety and compliance processes in the drone ecosystem. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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7 pages, 888 KB

Open AccessProceeding Paper

Analyzing at Scale the Effects of Optimal Global Sequence Alignment on Sequence Similarity Using a GPU-Optimized Implementation of the Needleman-Wunsch Algorithm and the SBERT Module

by Emilia Pardo, Valko Milev, Ventsislav Kolev and Maria Marinova

Eng. Proc. 2025, 100(1), 66; https://doi.org/10.3390/engproc2025100066 - 4 Aug 2025

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Abstract

Global sequence alignment remains a fundamental technique in bioinformatics, yet its large-scale application is often limited by computational demands. In this work, we explore the impact of optimal global sequence alignment on sequence similarity by combining a GPU-accelerated version of the Needleman–Wunsch algorithm [...] Read more.

Global sequence alignment remains a fundamental technique in bioinformatics, yet its large-scale application is often limited by computational demands. In this work, we explore the impact of optimal global sequence alignment on sequence similarity by combining a GPU-accelerated version of the Needleman–Wunsch algorithm with Sentence-BERT (SBERT), a transformer-based embedding model. This setup allows us to perform exhaustive alignments across large datasets while also capturing semantic similarities that traditional scoring schemes may miss. By comparing alignment scores with SBERT-derived similarity metrics, we examine where classical alignment aligns with—or diverges from—contextual similarity. Our results show that while there is general agreement between the two approaches, notable exceptions highlight cases where semantic meaning extends beyond structural alignment. The combination of efficient global alignment and deep semantic modeling offers new insights into the relationship between sequence form and function, opening the door for more nuanced similarity measures in both biological and textual sequence analysis. Full article

(This article belongs to the Proceedings of The 14th International Scientific Conference TechSys 2025—Engineering, Technologies and Systems)

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