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Publications - 6383

Experiments on the influence of oil temperature and pressure on subsynchronous bifurcation and shaft orbit behaviour in automotive turbochargers

Cs Tóth-Nagy Márk Pesthy

Publication Name: Mechanical Systems and Signal Processing

Publication Date: 2026-04-01

Volume: 249

Issue: Unknown

Page Range: Unknown

Description:

This work presents a comprehensive experimental study of the nonlinear dynamic behavior of a high-speed automotive turbocharger rotor system supported by semi-floating bearings. The investigation focuses on how oil supply temperature and pressure influence subsynchronous bifurcation, dynamic instability, and shaft orbit evolution under realistic lubrication environments. Experiments were performed on a dedicated test bench that enabled precise control and monitoring of oil parameters while decoupling rotor dynamics from engine-related disturbances.Shaft-end displacements were measured using dual radial probes, with simultaneous high-frequency vibration and speed tracking. Order spectra and Fourier analysis were conducted at key operational points, and orbit patterns were visualized through whirl plots to capture changes in rotor motion across a full range of speeds. The results reveal that elevated oil temperature markedly lowers the bifurcation threshold, causing nonlinear instabilities—marked by earlier onset of complex, multi-loop orbits—at reduced speeds. These transitions are dominated by two principal subsynchronous spectral components, Sub 1 (cylindrical and conical modes) and Sub 2 (translational and bending modes), whose evolution is mapped in detail using both spectral and orbit-based methods. A distinctive trend toward thermal saturation in the lubrication system was identified, as outlet oil temperature increases plateau at higher inlet temperatures, indicating a thermal energy absorption limit.Comparative analysis demonstrated that the system’s dynamic response is highly sensitive to both viscosity and supply pressure, with higher temperatures and lower viscosities amplifying instability and orbit complexity. Filtered vibration signals provided consistent results with displacement data, validating their use for practical bifurcation detection.By combining advanced order-domain diagnostics with direct orbit visualization, this study establishes clear experimental benchmarks for understanding turbocharger instability mechanisms, justifies the focus on the dominant subsynchronous modes, and highlights the importance of oil rheology and thermal effects in governing rotor dynamics. These insights support the development of improved predictive models and informed maintenance or control strategies for higher efficiency and reliability in turbocharger systems.

Open Access: Yes

DOI: 10.1016/j.ymssp.2026.114088

Integrating generative and parametric design with BIM: A literature review of challenges and research gaps in construction design

János Szép Álmos Semjén

Publication Name: Applications in Engineering Science

Publication Date: 2025-09-01

Volume: 23

Issue: Unknown

Page Range: Unknown

Description:

Parametric Design (PD), Generative Design (GD), and Building Information Modelling (BIM) have emerged as transformative tools in the construction industry, offering significant potential for design optimisation, interdisciplinary collaboration, and data-driven decision making. This paper presents a comprehensive literature review to evaluate the current state of PD, GD, and BIM integration, highlighting practical applications and identifying research gaps. In addition to mapping the academic discourse, the review also highlights selected practical implementations from existing literature to illustrate how these technologies are being translated into applied workflows. Furthermore, the methodology section critically reflects on the limitations of the keyword-based search strategy and suggests future directions to mitigate potential literature gaps. While many studies demonstrate efficiency gains in early design phases, the integration of these technologies across the full building lifecycle remains limited. Key challenges include insufficient interoperability between platforms, lack of standardisation, and minimal adoption of GD-BIM combinations in construction and logistics. Furthermore, few studies address the regulatory compliance and real-world scalability of AI-assisted generative models. The review concludes that although these digital methods can accelerate innovation and sustainability, their practical implementation requires further research in construction management, code-based automation, and human-in-the-loop design workflows.

Open Access: Yes

DOI: 10.1016/j.apples.2025.100253

Comparison of Italian and Hungarian Black Spot Ranking

Dániel Miletics Attila Borsos Salvatore Cafiso C. D'Agostino

Publication Name: Transportation Research Procedia

Publication Date: 2016-01-01

Volume: 14

Issue: Unknown

Page Range: 2148-2157

Description:

Black spot ranking is an important tool for finding the sites with potential safety improvement on the road network. The EU Directive on Road Infrastructure Safety Management also demands the ranking of high accident concentration sites. This paper gives an introduction to localizing high accident concentration sites and the indicators used by Italy and Hungary. Accident and traffic volume data are gathered for motorway sections from both countries. Safety ranking is made using two conventional indicators, absolute number of accidents and accident rate. A more sophisticated ranking using the Empirical Bayes method is applied. Expected average crash frequency with Empirical Bayes adjustment is calculated. Based on the estimation of the crash frequency, the Critical Crash Rate (CCR) was added to identify and rank black spots. This additional performance measure is able to take into account traffic volume as required by the EU Directive. Results of the Empirical Bayes method are compared with the conventional procedures. It is concluded that the results are not comparable; inasmuch as there are modifications in the order of black spots. Based on the comparison of results recommendations are given to change the practice in both countries.

Open Access: Yes

DOI: 10.1016/j.trpro.2016.05.230

Controlled bidirectional energy transfer by ultracapacitors in electric drive

Z. Puklus András Fehér

Publication Name: 12th IEEE International Symposium on Computational Intelligence and Informatics Cinti 2011 Proceedings

Publication Date: 2011-12-01

Volume: Unknown

Issue: Unknown

Page Range: 31-34

Description:

This paper shows the possibility of the two-directional energy transfer between energy sources using the example of ultracapacitors. The showed method allows bidirectional energy transfer between power systems which use different voltage levels. We used PSIM program to simulate the bidirectional energy transfer and study the operation of the applied model. © 2011 IEEE.

Open Access: Yes

DOI: 10.1109/CINTI.2011.6108526

An effective reduction method with Caughey damping for spurious oscillations in dynamic problems

Balázs Pere Daniel Serfozo

Publication Name: Meccanica

Publication Date: 2025-09-01

Volume: 60

Issue: 9

Page Range: 2927-2946

Description:

The numerical solution of dynamic problems often results spurious oscillations. In order to eliminate them, a damping effect must be included in the numerical scheme. However, the concrete shape of the damping characteristics has a great importance in the efficiency of oscillation reduction. In this article, a novel approach has been introduced with adjustable damping character. The damping effect is exerted as viscous damping according to the formulation of Caughey damping. Using the proposed method, a wide range of damping curves can be approximated with high accuracy. The newly developed method is mainly useful for contact-impact and wave propagation problems.

Open Access: Yes

DOI: 10.1007/s11012-025-02036-9

The probability of obstructive sleep apnea disorders emergence by odds ratio of main risk factors

Ferenc Ihász Krisztina Szabó

Publication Name: Orvosi Hetilap

Publication Date: 2017-05-01

Volume: 158

Issue: 21

Page Range: 823-828

Description:

Introduction: The quality of sleep plays a serious role in the individual's daytime performace and state of health, there by it has a strong influence on the society. Aim: The present study measures the probability developing and severity of obstructive sleep apnea syndrome, - which belongs to group of disorders of the respiratory - through odds ratio of leading risk factors. Method: 127 persons were examined in the test. The sleep structure test data were processed by polysomnographic screening device. Results: The nutritional level of body in mass index (BMI), and the neck circumferences data were recorded in cm. On the basis of the examination the gender as a risk factor it can be said that the odds ratio for men compared to women, more than three times higher of emergence of disease. Conclusions: Men's chance of the emergence of serious disease is more than four times higher than women's chance. In the men's test group the most significant predictor of obstructive sleep apnea amongst the risk factors is the circumference according to odds ratio. In women's group the leader odds ratio is BMI. More than 50% of test goup don't report about daytime sleepiness, and this fact draws our attention to the role of risk factors' odds ratio in selection.

Open Access: Yes

DOI: 10.1556/650.2017.30742

Adaptive improvement of a passive antilock brake control

J. O. Pedro S. John László T. Kóczy

Publication Name: IEEE AFRICON Conference

Publication Date: 2011-12-12

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

The use of reliable or at least realistic friction models is a key factor in simulation studies related to antilock brake control systems. In the literature a plethora of strongly nonlinear tyre-road friction models are available. Certain models have singular expressions in the arguments of exponential terms in the vicinity of zero car body velocity though this region has practical significance. Since the parameters of these singular models may quickly vary in time with the variation of the road conditions their realtime identification was evaded in a paper that applied a simple observer instead. This method has been improved in the present paper by applying a novel adaptive technique for compensating the effects of the imprecisely known other (i.e. not related to the tyre-road friction) parameters. By the use of a particular friction model it was found via simulations that the adaptive technique can considerably shorten the braking distance. © 2011 IEEE.

Open Access: Yes

DOI: 10.1109/AFRCON.2011.6072040

Machine learning and fuzzy cognitive maps in a hybrid approach toward freeway on-ramp traffic control

Miklós F. Hatwágner Mehran Amini László T. Kóczy

Publication Name: Saci 2023 IEEE 17th International Symposium on Applied Computational Intelligence and Informatics Proceedings

Publication Date: 2023-01-01

Volume: Unknown

Issue: Unknown

Page Range: 587-591

Description:

The infrequent emergence of traffic congestion on freeways can result in the decline of the transportation system over time. Without the implementation of appropriate countermeasures, congestion can escalate, leading to unfavorable impacts on other aspects of the traffic network. As a result, there is a greater need for reliable and optimal traffic control. The goal of this research is to manage the number of vehicles entering the main freeway from the ramp merging area, in order to balance the demand and capacity to satisfy the maximum utilization of the freeway capacity. Despite extensive research into different ramp metering techniques, this study aims to utilize the fuzzy cognitive map as a macroscopic traffic flow model in conjunction with the Q-learning algorithm. This combination prevents freeway congestion and maintains optimal performance by keeping freeway density below a key threshold. The inherent uncertainty of traffic conditions is addressed through the application of reinforcement learning, which is constructed on the principles of the Markov decision process. This approach represents an exploration-exploitation trade-off, as implemented through the Q-learning algorithm. The proposed technique was evaluated for its efficacy in the regulation of freeway ramp metering in both controlled and uncontrolled simulations. The findings demonstrate a significant improvement in the control of the mainstream traffic flow.

Open Access: Yes

DOI: 10.1109/SACI58269.2023.10158585

Numerical modelling of a solenoid optimization problem with a superposition-based model order reduction method

Tamas Orosz Kristóf Levente Kiss

Publication Name: Computers and Structures

Publication Date: 2025-09-01

Volume: 316

Issue: Unknown

Page Range: Unknown

Description:

This work investigates the application of a Model Order Reduction technique based on the Cauer ladder network method to the air cored solenoid geometry of the number 35 benchmark problem from the Testing electromagnetic analysis methods series, approaching both source and discrete radius optimization tasks. A projection-based reduced-order model was developed to accelerate the optimization process, achieving an average computational speedup factor of 35 compared to full-order finite element simulations. For discrete radius optimization, the problem was reformulated as a source optimization, enabling effective model order reduction application. The multiport Cauer ladder network approach reduced to a superposition of magnetic fields due to the simplicity of the problem. The reduced order model preserved consistency with the full order model when a small enough element size was chosen in the finite element model during its creation process. The error of the proposed methodology is an order of magnitude lower than the lowest objective function values in the optima, therefore it is suitable for multi-objective optimization.

Open Access: Yes

DOI: 10.1016/j.compstruc.2025.107906