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Engineering Proceedings, Volume 121, Issue 1

2026 BulTrans 2025 - 33 articles

The 17th International Scientific Conference on Aerospace, Automotive, and Railway Engineering

Sozopol, Bulgaria | 10–13 September 2025

Volume Editors:

Krasin Georgiev, Faculty of Transport, Technical University of Sofia, Sofia, Bulgaria

Stoilova Svetla, Faculty of Transport, Technical University of Sofia, Sofia, Bulgaria

Cover Story: The 17th International Scientific Conference on Aeronautics, Automotive and Railway Engineering and Technologies (BulTrans-2025) was held at the Summer Holiday House of Technical University of Sofia in Sozopol, 10th–13th September 2025. Bultrans is the most prestigious scientific forum for road, rail and air transport in Bulgaria. It is organised by TU-Sofia as part of a group of conferences, called "Science Days of Technical University of Sofia". The topics of the conference include Aeronautics and Astronautics; Automotive Engineering and Technologies; Internal Combustion Engines and Alternative Fuels; Railway Engineering and Technologies; Transport Management and Logistics; and Dynamics, Strength and Reliability in Transport. The conference was held in a hybrid format with on-site and remote participation.
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Articles (33)

  • Proceeding Paper
  • Open Access
40 Views
11 Pages

2 February 2026

The subject of this study is the dynamic analysis of the energy flow in the transient mode of the movement of the vehicle with a kinetic accumulator, implemented with a purely mechanical transmission. The elements of which include—a flywheel, p...

  • Proceeding Paper
  • Open Access
118 Views
13 Pages

Prediction of the Spare Parts Range Based on Time and Economic Factors

  • Oleksandr Kravchenko,
  • Ján Dižo,
  • Andrej Suchánek and
  • Kristína Kozáková

3 February 2026

This work examines the results of research into internal combustion engine malfunction using the example of a vehicle control group of a specific transport company during the warranty and post-warranty periods. Studies have established that the most...

  • Proceeding Paper
  • Open Access
108 Views
14 Pages

2 February 2026

This paper applies the recently developed Prediction-Based Control Barrier Functions (PB-CBFs) to the obstacle avoidance problem for multirotor air taxis in Urban Air Mobility (UAM). Unlike conventional Control Barrier Functions (CBFs), PB-CBFs incor...

  • Proceeding Paper
  • Open Access
131 Views
10 Pages

On the Aerodynamic Characteristics of the Aurel Persu Car

  • Adrian Clenci,
  • Amélie Danlos,
  • Ivan Dobrev and
  • Victor Iorga-Simăn

21 January 2026

This study investigates the aerodynamics of Romanian engineer Aurel Persu’s car through wind tunnel experiments involving force measurements, Particle Image Velocimetry (PIV), and CFD simulations. Tests using scale models revealed significant f...

  • Proceeding Paper
  • Open Access
111 Views
14 Pages

19 January 2026

Active Debris Removal (ADR) missions demand precise and rapid controllers that lower collision risks specifically in the capture phase of tumbling objects. Sliding Mode Control (SMC), in general, offers robustness against model uncertainties. However...

  • Proceeding Paper
  • Open Access
148 Views
15 Pages

An Integrated Model for the Electrification of Urban Bus Fleets in Public Transport Systems

  • Velizara Pencheva,
  • Asen Asenov,
  • Aleksandar Georgiev,
  • Kremena Mineva and
  • Mladen Kulev

20 January 2026

The article explores the current challenges and prospects for the electrification of the bus fleet in urban passenger transport, with a particular focus on the municipal operator Municipal Transport Ruse EAD. The study is motivated by the growing imp...

  • Proceeding Paper
  • Open Access
385 Views
9 Pages

Legal Frameworks for Asteroid Mining: Techno-Economic Impacts and Regulatory Needs

  • Hamideh Azimzadeh,
  • Mahsa Azadmanesh,
  • Radina Nikolova and
  • Roya Asiaei

20 January 2026

The current space law does not clarify the asteroid mining problem enough. This paper presents a techno-economic analysis to show how legal certainty impacts the profitability and overall investment in asteroid mining projects. Our analysis reveals t...

  • Proceeding Paper
  • Open Access
158 Views
14 Pages

Onboard Deep Reinforcement Learning: Deployment and Testing for CubeSat Attitude Control

  • Sajjad Zahedi,
  • Jafar Roshanian,
  • Mehran Mirshams and
  • Krasin Georgiev

20 January 2026

Recent progress in Reinforcement Learning (RL), especially deep RL, has created new possibilities for autonomous control in complex and uncertain environments. This study explores these possibilities through a practical approach, implementing an RL a...

  • Proceeding Paper
  • Open Access
343 Views
12 Pages

19 January 2026

This study develops a hyperbolic tangent-based model for the hysteretic behavior of automotive grade electrohydraulic semi-active dampers. Model parameters were identified from experimental force–velocity data gathered under sinusoidal excitati...

  • Proceeding Paper
  • Open Access
166 Views
10 Pages

16 January 2026

This paper presents a method for dimensional synthesis of a pulse-type adjustable speed mechanical drive, realized through a Watt II six-bar linkage combined with an overrunning clutch. The goal is to achieve a transmission ratio that varies smoothly...

  • Proceeding Paper
  • Open Access
239 Views
23 Pages

Modelling Heat Recovery System for Efficiency Enhancement in Alkaline Electrolyser

  • Mohamed Amin,
  • Edward Antwi,
  • Taimoor Khan,
  • Romy Sommer,
  • Qahtan Thabit and
  • Johannes Gulden

16 January 2026

The global energy landscape is transitioning towards cleaner solutions, with hydrogen emerging as a key energy source. To unlock hydrogen’s potential, it is crucial to prioritize the development of a more efficient, cost-effective, and environm...

  • Proceeding Paper
  • Open Access
331 Views
16 Pages

Simulating Road Networks for Medium-Size Cities: Aswan City Case Study

  • Seham Hemdan,
  • Mahmoud Khames,
  • Abdulmajeed Alsultan and
  • Ayman Othman

16 January 2026

This research simulates Aswan City’s urban transportation dynamics utilizing the Multi-Agent Transport Simulation (MATSim) framework. As a fast-expanding urban center, Aswan has many transportation difficulties that require extensive modeling t...

  • Proceeding Paper
  • Open Access
209 Views
10 Pages

Experimental Study of Flow Around Stepped NACA 0015 Airfoils at Low Reynolds Numbers

  • Ivan Dobrev,
  • Michael Pereira,
  • Michael Todorov and
  • Fawaz Massouh

15 January 2026

This study investigates the flow around Kline-Fogleman (KF) airfoils using Particle Image Velocimetry (PIV) in a wind tunnel at Reynolds number Re = 6.8 × 104. Three configurations are tested: a clean NACA 0015 airfoil and two modified versions...

  • Proceeding Paper
  • Open Access
195 Views
8 Pages

16 January 2026

The current study presents results from experimental tests of productivity, fuel consumption, and fuel efficiency of a wheeled excavator Hyundai HW160A that were performed at a construction site in Sofia, Bulgaria. The experiments happened during the...

  • Proceeding Paper
  • Open Access
318 Views
14 Pages

Campfire: Innovative Cost Modeling and Market Forecasting for Ammonia as a Maritime Fuel

  • Mohamed Amin,
  • Edward Antwi,
  • Mirko Post,
  • Romy Sommer,
  • Qahtan Thabit and
  • Johannes Gulden

16 January 2026

In recent years, Ammonia has emerged as a promising carbon-free fuel alternative, offering considerable potential to reduce CO2 emissions and contribute to the decarbonization of the transportation industry. This study focuses on the economic feasibi...

  • Proceeding Paper
  • Open Access
264 Views
14 Pages

14 January 2026

The present literature review identifies substantial research and applied potential in the combined utilization of internationally recognized information security standards, Bayesian networks, and AI-based assistants to enhance cyber resilience in Un...

  • Proceeding Paper
  • Open Access
220 Views
10 Pages

14 January 2026

This study provides a comparison between the impact of two gas fuels, compressed natural gas (CNG) and hydrogen (H2), on the exhaust emissions of a single-cylinder diesel engine operating in dual-fuel mode. The analysis is conducted with a constant a...

  • Proceeding Paper
  • Open Access
215 Views
11 Pages

The Influence of Printing Parameters on the Impact Strength of FDM 3D-Printed Polylactic Acid

  • Tsvetomir Gechev,
  • Veselin Tsonev,
  • Petar Ivanov,
  • Ivan Kralov and
  • Krasimir Nedelchev

13 January 2026

The paper investigates experimentally the influence of infill density, infill pattern, layer height, wall number, printing orientation, and material color on the impact strength of 3D-printed PLA (polylactic acid) samples by using the Charpy test met...

  • Proceeding Paper
  • Open Access
219 Views
11 Pages

Design and Verification of Computation Model of Side Flap of Wagon Series Rens

  • Vladislav Maznichki,
  • Svetoslav Slavchev,
  • Stefan Krastev and
  • Stancho Ivanov

13 January 2026

Side flaps are critical structural components of flat freight wagons, directly affecting cargo safety during transportation and playing an essential role in loading and unloading operations. Over the years, their reliability has been well established...

  • Editorial
  • Open Access
154 Views
3 Pages

14 January 2026

The BulTrans International Scientific Conference on Aeronautics, Automotive, and Railway Engineering and Technologies is organized by the Faculty of Transport, Technical University of Sofia [...]

  • Proceeding Paper
  • Open Access
220 Views
12 Pages

Effect of Temperature Variations on Brake Squeal Characteristics in Disc Brake Systems

  • Akif Yavuz,
  • Osman Taha Sen,
  • Mustafa Enes Kırmacı and
  • Tolga Gündoğdu

13 January 2026

Brake squeal is an undesirable high-frequency noise caused by vibrations induced by friction in disc brake systems. The noise is strongly affected by temperature, as this influences the material properties of the friction pair and the dynamic behavio...

  • Proceeding Paper
  • Open Access
375 Views
9 Pages

An Assessment of Diesel Engine Performance Using a Dual-Fuel Diesel—Ammonia Injection

  • Lucian Miron,
  • Vlad-Alexandru Ungureanu,
  • Radu Ionescu and
  • Radu Chiriac

13 January 2026

In the context of promoting strategies to mitigate the global warming effect resulting from greenhouse gas emissions produced by human activities, ammonia stands out as an important player in the decarbonization of various sectors, including transpor...

  • Proceeding Paper
  • Open Access
266 Views
13 Pages

Virtual and Physical Prototyping in Mechanical Shock Test of an EV Battery Module

  • Georgi Todorov,
  • Konstantin Kamberov,
  • Tsvetozar Ivanov and
  • Konstantin Dimitrov

13 January 2026

This study presents a methodology used in the design certification of a battery module for electric vehicle applications. The methodology combines virtual and physical techniques to assess the structure under mechanical shock testing, according to th...

  • Proceeding Paper
  • Open Access
171 Views
13 Pages

Investigation of the Influence of Distributor Valve Position on Longitudinal Train Dynamics During Braking

  • Stefan Krastev,
  • Svetoslav Slavchev,
  • Vladislav Maznichki,
  • Petko Sinapov and
  • Magdalen Velev

13 January 2026

The distributor valve is one of the most important components in the pneumatic braking system of trains. It performs the functions of filling and releasing the brake cylinder. The distributor valve most widely used on Bulgarian railways operates in t...

  • Proceeding Paper
  • Open Access
286 Views
13 Pages

12 January 2026

This article describes the possibilities of using universal flat wagons to transport long cargoes and suggests measures for upgrading them, which involve the installation of superstructures on the load-bearing structures to keep the cargo from overtu...

  • Proceeding Paper
  • Open Access
514 Views
10 Pages

13 January 2026

This paper examines the application of Artificial Intelligence (AI) to protect satellite communication networks, focusing on the identification and prevention of cyber threats. With the rapid development of the commercial space sector, the importance...

  • Proceeding Paper
  • Open Access
225 Views
17 Pages

Optimization of Feeder Buses Route to Connect High-Speed Railway Stations with Urban Areas

  • Seham Hemdan,
  • Mostafa Ramadan,
  • Abdulmajeed Alsultan and
  • Ayman Othman

12 January 2026

Feeder buses play an important role in supporting the accessibility of high-speed railway stations which leads to the improved efficiency of the transportation system. This paper proposes a new optimization technique for the design of feeder bus rout...

  • Proceeding Paper
  • Open Access
215 Views
9 Pages

12 January 2026

The present paper investigates the dynamic behavior of an unbalanced rotor mounted in a balancing machine. Differential equations of motion are derived without linearization using Lagrange equations of the second kind to determine the nonlinear natur...

  • Proceeding Paper
  • Open Access
207 Views
12 Pages

12 January 2026

A new hybrid forecasting model of the number of freight trains is proposed in this paper. This forecasting is performed by combining classification analysis and the use of Histogram-based Gradient Boosting Regressor (HGBR). The freight trains were cl...

  • Proceeding Paper
  • Open Access
231 Views
13 Pages

12 January 2026

Nowadays, the automotive industry is primarily driven by the CO2 policy that targets net zero carbon emissions by 2035 from passenger cars and commercial vehicles. The main path to achieve this goal is the implementation of electric powertrains with...

  • Proceeding Paper
  • Open Access
264 Views
13 Pages

Study of Strength of Open Wagon with Tank Containers Under Operational Modes

  • Alyona Lovska,
  • Juraj Gerlici,
  • Ján Dižo and
  • Pavlo Rukavishnikov

A removable module design is proposed to enable the use of open wagons for container transport. It acts as an intermediate adapter between an open wagon body and a tank container, ensuring the possibility of their reliable interaction. The dynamic lo...

  • Proceeding Paper
  • Open Access
274 Views
15 Pages

This article represents a numerical approach for estimating the helicopter rotor’s blade longitudinal dynamic characteristics considering several operational parameters. A characterization regarding the blade’s longitudinal, flapping, and...

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Eng. Proc. - ISSN 2673-4591