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Found 6414 publications

Finite element analysis of bridge transition zone for investigating the effect of moving loads

E. Koch

Publication Name: 17th European Conference on Soil Mechanics and Geotechnical Engineering Ecsmge 2019 Proceedings

Publication Date: 2019-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

The problem of track-bridge interaction and its modeling issues have increasingly been emphasized and highlighted due to the presence of high-speed rails. The quality criteria for high-speed rail lines must be stricter than those for conventional rail lines to assure passenger comfort and safety. Experience shows that in transition zones when a train rides from an embankment onto a stiff structure, such as a bridge, tunnel or culvert, an abrupt change occurs in the support stiffness possibly inducing differential settlements. Examples prove that inadequate technical solutions can generate damage that may require long term speed restrictions or lead to short maintenance cycles, significantly increasing the total cost of ownership. The problems associated with the transition zones require complex analysis. The author reports the results obtained by the investigation of a 3D numerical model of a bridge transition zone by means of an advanced constitutive model and time domain analysis. The mechanical behavior of a railway bridge and its soil environment is presented in the study with special regards to factors like train speed, embankment height and the settlement differences apparently developing in the transition zone.

Open Access: Yes

DOI: 10.32075/17ECSMGE-2019-0137

Numerical Determination of Contact Radii in Rail-Wheel Contact

Szabolcs Fischer Zoltán Major Attila Németh Vivien Jóvér

Publication Name: Lecture Notes in Networks and Systems

Publication Date: 2026-01-01

Volume: 1768 LNNS

Issue: Unknown

Page Range: 55-65

Description:

In this paper, the authors present a method for determining the contact radii required to calculate contact stresses, even for distorted rail-wheel contact geometries. This deformation is most often caused by wear between the wheel and rail. In the method used, the authors employ numerical differentiation to derive the required radius values from the data of discrete points defined in the Cartesian x-y coordinate system. The authors validate the applicability of their method on a rail head of 60E1 geometry without wear. A further objective of research is to validate the method for worn geometries. The presented method will help experts obtain a more accurate view of the magnitude of contact stresses, as the formulas used in everyday practice are often significantly incorrect, to the detriment of safety. Thus, by going beyond methods that use a single radius value, they also demonstrate that the calculation of accurate values requires knowledge of four radius values, two of which can be determined effectively using the presented methodology.

Open Access: Yes

DOI: 10.1007/978-3-032-13898-9_6

Computational simulation of mesopic vision based on camera recordings

Gábor Dömötör András Horváth

Publication Name: Light and Engineering

Publication Date: 2014-01-01

Volume: 22

Issue: 1

Page Range: 61-67

Description:

Understanding mesopic vision is one of the hottest topics in lighting engineering [1]. The high importance of the field comes from the wide variety of the applications such as driving and other outdoor activities are performed in mesopic conditions at night. Therefore, it is extremely important to calculate the visibility of different objects in such conditions. In this paper, we present the algorithm and the first results of software, which is able to simulate the behaviour of human retina in scotopic, mesopic and photopic ranges, calculates the direction-dependent acuity. Our aim was to produce a practical tool to examine real-time situations. Therefore, classical camera recordings are used as input, which limits the accuracy but extends the range of applications.

Open Access: Yes

DOI: DOI not available

The Forerunner UAV Concept for the Increased Safety of First Responders

Antal Hiba Ádám Kisari Mihály Nagy Istvan Drotar Attila Gáti Péter Bauer Balázs Lattes

Publication Name: International Conference on Vehicle Technology and Intelligent Transport Systems Vehits Proceedings

Publication Date: 2021-01-01

Volume: 2021-April

Issue: Unknown

Page Range: 362-369

Description:

This paper proposes a novel Forerunner UAV concept to increase the safety of first responders by monitoring the road in front of their emergency ground vehicle (EGV) and notifying the driver about any violation of his/her right of way or approaching danger. The developments are conducted in an R&D project in Hungary. The proposed UAV for the planned urban demonstration is a hexacopter with triple redundant architecture applying a gimbaled camera to monitor the surroundings. In the cooperative control of the EGV and UAV the UAV must fly in front of the EGV which is possible through wireless communication of route data and velocity. Besides the real system a computer simulation representation is also applied including CARLA and Matlab to make exhaustive tests of the system capabilities. Increased attention is devoted to the possible wireless communication solutions as these are safety critical parts of the system. The article ends with the lists of planned simulation and real test scenarios to evaluate the system.

Open Access: Yes

DOI: DOI not available

Artificial Intelligence-Based Colorectal Polyp Histology Prediction by Using Narrow-Band Image-Magnifying Colonoscopy

Istvan Racz Henriett Regoczi Noemi Kranitz András Horváth Gyongyi Kiss Zoltán Horváth

Publication Name: Clinical Endoscopy

Publication Date: 2022-01-01

Volume: 55

Issue: 1

Page Range: 113-121

Description:

Background/Aims: We have been developing artificial intelligence based polyp histology prediction (AIPHP) method to classify Narrow Band Imaging (NBI) magnifying colonoscopy images to predict the hyperplastic or neoplastic histology of polyps. Our aim was to analyze the accuracy of AIPHP and narrow-band imaging international colorectal endoscopic (NICE) classification based histology predictions and also to compare the results of the two methods. Methods: We studied 373 colorectal polyp samples taken by polypectomy from 279 patients. The documented NBI still images were analyzed by the AIPHP method and by the NICE classification parallel. The AIPHP software was created by machine learning method. The software measures five geometrical and color features on the endoscopic image. Results: The accuracy of AIPHP was 86.6% (323/373) in total of polyps. We compared the AIPHP accuracy results for diminutive and non-diminutive polyps (82.1% vs. 92.2%; p=0.0032). The accuracy of the hyperplastic histology prediction was significantly better by NICE compared to AIPHP method both in the diminutive polyps (n=207) (95.2% vs. 82.1%) (p<0.001) and also in all evaluated polyps (n=373) (97.1% vs. 86.6%) (p<0.001) Conclusions: Our artificial intelligence based polyp histology prediction software could predict histology with high accuracy only in the large size polyp subgroup.

Open Access: Yes

DOI: 10.5946/ce.2021.149

Review and conceptual design of FPGA-based application for data-driven power electronic systems

Adrienn Dineva Adam Zsuga

Publication Name: 2021 17th Conference on Electrical Machines Drives and Power Systems Elma 2021 Proceedings

Publication Date: 2021-07-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

AI-based data-driven methods are an emerging research direction in the field of power electronics. However, because of the absence of large datasets, the development of these solutions have some barriers to overcome. To properly train machine learning algorithms and neural networks a large amount of training data is necessary. This dataset can be a union of simulation and measured data. Generating simulation data with computer simulations can be slow process and gathering real data is not cost-effective. Real-Time simulators based on FPGAs can be powerful tools to accelerate simulation, and create datasets for AI applications in a cost-effective and accurate way. In this paper the possible FPGA-based solutions, which can be applicable for the problems, have been reviewed. Their applicability have been discussed, moreover a simplified FPGA-based concept have been designed and embedded into two possible AI-based application area.

Open Access: Yes

DOI: 10.1109/ELMA52514.2021.9503033

Hausdorff dimension of univoque sets

Gábor Kallos

Publication Name: Acta Cybernetica

Publication Date: 1999-01-01

Volume: 14

Issue: 2

Page Range: 303-314

Description:

In this paper we present the results obtained so far for the determination of the Hausdorff dimension of the univoque set, in number systems with base number greater than 1. The investigation is based on the methods presented in [1] and [2]. We illustrate the theoretical results with interesting examples.

Open Access: Yes

DOI: DOI not available

Thermal examination of a simplified exhaust tube-heatshield model

Balázs Vehovszky Tamás Jakubík Marcell Treszkai

Publication Name: Periodica Polytechnica Transportation Engineering

Publication Date: 2019-01-01

Volume: 47

Issue: 3

Page Range: 190-195

Description:

Exhaust system and its surrounding is a thermally highly critical part of a vehicle: during forced operation, hottest elements can reach 600 °C. The thermal conditions turn to even more critical if the forced flow leaves off – e.g. when the car stops at a highway parking place. In such a case not only the cooling effect of cross-flow disappears, but the natural convection starts to bring heat toward nearby elements – resulting potential overheating of concerned parts. A measurement setup for modelling such case was built, and different parameters were examined, which have influence on the heating of aluminium heatshield above the exhaust tube. Measurements were complemented by CFD simulations and flow visualization technique aiming the better understanding of evolving thermal and flow conditions.

Open Access: Yes

DOI: 10.3311/PPtr.12109

Spatial Metaphors in Reporting Emotions: The use of Emotional Deixis in Interviews with Parents of Children with a Language Disorder

Judit Baranyiné Kóczy Krisztina Zajdó

Publication Name: Lublin Studies in Modern Languages and Literature

Publication Date: 2023-01-01

Volume: 47

Issue: 2

Page Range: 47-59

Description:

The paper explores how Hungarian parents of children with a language disorder use emotional deixis to report their child’s condition. Demonstrative pronouns and the metaphorical meaning of space, particularly proximity, are observed in a corpus of six interviews. The questions raised are: a) What entities and relations are typically referenced by emotional deixis? b) What kinds of metaphorical meanings are conveyed by spatial closeness in the use of demonstrative pronouns? Results show that the parents use proximal emotional deixis differently from the usual pattern; instead of expressing their internal direct and positive experience, they employ them to report fundamentally negative experiences of the child’s condition, development, diagnosis or therapy, or other negative experiences. Such application of emotional deixis indicates an intense and vivid experience, namely mental and emotional proximity to negative experiences, which stems from the empathic parental role.

Open Access: Yes

DOI: 10.17951/lsmll.2023.47.2.47-59