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Found 6515 publications

A simple technique to estimate the processing window for laser clad coatings

K. Zoltan Lino Costa B. Verö Imre Felde R. Colaço Tamás Réti R. Vilar

Publication Name: International Surface Engineering Congress Proceedings of the 1st Congress

Publication Date: 2003-12-01

Volume: Unknown

Issue: Unknown

Page Range: 237-242

Description:

A semi-empirical method for selecting the processing parameters of laser cladding is proposed. This phenomenological approach uses simple mathematical formulae, derived from a statistical analysis of measured data, to relate the laser cladding parameters with the geometric features of the clad track. Given the required clad height and available laser beam power, the proposed method allows one to calculate values of the scanning speed and powder feed rate which are used to obtain low dilution, pore free coatings, fusion bonded to the substrate. To illustrate the application of this method, variable powder feed rate laser cladding experiments were carried out with Stellite 6 powder on mild steel substrates. In this technique the laser beam power and radius and the processing speed are kept constant, while the powder feed rate is varied along a single track length according to a specified linear function. The expressions derived from the model were used to plot the experimental data in a coherent manner, revealing the combined role of the different processing parameters.

Open Access: Yes

DOI: DOI not available

Aerobic Capacity, Body Composition, and Ventilatory Thresholds in Youth Endurance Athletes: Physiological Characteristics of Hungarian Junior Triathletes

Ferenc Ihász István Barthalos László Suszter Árpád Petrov Ádám Balog Zoltán Alföldi

Publication Name: Applied Sciences Switzerland

Publication Date: 2026-05-01

Volume: 16

Issue: 9

Page Range: Unknown

Description:

Limited data are available regarding the physiological profile of youth triathletes. The aim of this study was to characterize the physiological and body composition profile of Hungarian youth triathletes and to examine the relationships between anthropometric characteristics and aerobic performance indicators. Forty-one youth triathletes (20 females and 21 males; age: 15.8 ± 1.7 years), members of the Hungarian national development squad, participated in the study. Anthropometric and body composition parameters were assessed using standardized procedures and multi-frequency bioelectrical impedance analysis. Aerobic performance was evaluated using a graded cardiopulmonary exercise test on a treadmill with breath-by-breath gas analysis. Male athletes demonstrated higher body height, body mass, fat-free mass, and skeletal muscle mass compared with females (p < 0.05). Cardiopulmonary exercise testing revealed high aerobic capacity, with mean VO2max values of 73.2 ± 5.4 mL·kg−1·min−1 in males and 63.1 ± 5.0 mL·kg−1·min−1 in females. The second ventilatory threshold occurred at approximately 82–86% of VO2max. Strong positive correlations were observed between anthropometric parameters and absolute oxygen uptake (mL·min−1), particularly for fat-free mass, skeletal muscle mass, and body surface area (r = 0.83–0.95). However, these relationships are influenced by body size and were weaker or inverse when relative oxygen uptake (mL·kg−1·min−1) was considered. Regression analyses further indicated that body composition variables, especially fat-free mass and skeletal muscle mass, were positively associated with aerobic performance, while body fat percentage was not a significant predictor when body size and sex were controlled. These findings are based on cross-sectional associations and should be interpreted as descriptive reference data for this population rather than predictive criteria. The results contribute to the characterization of physiological and anthropometric profiles in youth triathletes and may support future research and athlete monitoring.

Open Access: Yes

DOI: 10.3390/app16094449

Multi-objective optimization of building envelopes by bacterial memetic algorithms

János Botzheim Árpád Csík

Publication Name: 2013 World Congress on Nature and Biologically Inspired Computing Nabic 2013

Publication Date: 2013-11-22

Volume: Unknown

Issue: Unknown

Page Range: 245-252

Description:

In the present paper, we apply bacterial memetic algorithms in the context of multi-objective optimization. The goal of the development is to optimize the energetic quality of residential building envelopes in a sustainable manner. Our interest is to determine a good compromise between the quality of the building envelope and the total cost of the installed energy saving components. We provide a description of the applied bacterial operators and the particular ordering of the population that is a non unique procedure. In order to refine the ordering we implement a variant of the distance metric for comparing the non-comparable individuals. The numerical computations are performed by the EnergOpt computational framework of the authors. The performance of the algorithm is demonstrated on the solution of a benchmark test case. Finally, the optimization of an existing building is presented to demonstrate the potential of the methodology. © 2013 IEEE.

Open Access: Yes

DOI: 10.1109/NaBIC.2013.6617870

Learning Factories towards Industry 5.0: Evolutionary or Revolutionary?

No authors available

Publication Name: 19th IMEKO TC10 Conference "MACRO meets NANO in Measurement for Diagnostics, Optimization and Control"

Publication Date: 2023-01-01

Volume:

Issue:

Page Range: Unknown

Description:

Rather than representing a technological leap forward, Industry 5.0 actually nests the Industry 4.0 approach in a broader context, providing regenerative purpose and directionality to the technological transformation of industrial production for people-planet-prosperity [1]. Consequently, Industry 5.0 can be considered as the new engine of the economic and societal transition with a societal concept which can mean more distributed well-being with human-centric and sustainable, resilient industry. The advantage of the learning factory concept therefore lies in the combination of the realistic factory environment, processes and transparency of the structured activities which can provide testing of new features, modules, functionalities, tools, and technologies based on the existing Industry 4.0 framework. Especially, the concepts of implementing new business models with benchmarking emphasise the major difference in achievable results. Transition to a circular economy can only be achieved if up-skilling and re-skilling of workers can also be done which is the core function of the learning factory.

Open Access: No

DOI: DOI not available

An update on recurrent acute pancreatitis: Data from five European countries

Gyula Farkas Hans Beger Paul Lankisch Philippe Levy Raffaele Pezzilli Lucio Gullo Constantine Arvanitakis Marina Migliori Attila Oláh

Publication Name: American Journal of Gastroenterology

Publication Date: 2002-08-01

Volume: 97

Issue: 8

Page Range: 1959-1962

Description:

OBJECTIVE: A great number of studies have been published on acute pancreatitis, but few have focused on the recurrent form. In this study, we have sought to determine the relative frequency and mortality of recurrent acute pancreatitis, and also to update our knowledge of its etiological factors. METHODS: Patients were selected from a total of 1068 persons included in a previous European study of acute pancreatitis. All were admitted to a hospital with an attack of acute pancreatitis between January, 1990 and December, 1994. Data for each patient was recorded on a standardized form. RESULTS: Of the 1068 with acute pancreatitis, 288 (27%) had recurrent pancreatitis; the majority (78.8%) were men, with a mean age of 43 yr (range 16-95 yr). Regarding etiology, alcohol was the most frequent factor (57%), followed by gallstones (25%), other factors (7.6%), and no identified factor (10.4%). Of the 288 patients, 17 (5.9%) died, all of whom had necrotizing pancreatitis; among all of the patients with necrotizing pancreatitis (141 of 288), the mortality was 12.1%. These percentages are lower than those for patients who had a single attack (8.5% and 18.6%, respectively), but not to a statistically significant degree. Mortality was significantly lower among patients with alcoholic pancreatitis (6.9%) than among those with biliary (30%) (p < 0.002) or idiopathic pancreatitis (25%) (p < 0.04). Most of the deaths (82.4%) occurred at the second attack of pancreatitis. CONCLUSION: Acute recurrent pancreatitis remains a frequent disease, with alcohol being the most frequent etiological factor. Mortality is similar to that of a single episode of acute pancreatitis, and it is significantly lower among patients with alcohol as the etiology. © 2002 by Am. Coll. of Gastroenterology.

Open Access: Yes

DOI: 10.1016/S0002-9270(02)04264-8

Reinforcement Learning-Based Robust Vehicle Control for Autonomous Vehicle Trajectory Tracking †

Balazs Nemeth Peter Gaspar Attila Lelkó

Publication Name: Engineering Proceedings

Publication Date: 2024-01-01

Volume: 79

Issue: 1

Page Range: Unknown

Description:

This publication presents a new method by which control methods based on reinforcement learning can be combined with classical robust control methods. The combination results in a robust management system that meets high-quality criteria. The described method is presented through the control of an autonomous vehicle. By choosing the reward function chosen during reinforcement learning, various driving styles can be realized, e.g., lap time minimization, track tracking, and travel comfort. The neural network was trained using the Proximal Policy Optimization algorithm, and the robust control is based on (Formula presented.). The two controllers are combined using a supervisor structure, in which a quadratic optimization task is implemented. The result of the method is a control structure that realizes the longitudinal and lateral control of the vehicle by specifying the reference speed and the steering angle. The effectiveness of the algorithm is demonstrated through simulations.

Open Access: Yes

DOI: 10.3390/engproc2024079030

Ranking of beef cattle sires by their breeding value on progeny performance

Szabolcs Bene J. Péter Polgár Márton Szűcs Ferenc Szabó

Publication Name: Journal of Central European Agriculture

Publication Date: 2020-01-01

Volume: 21

Issue: 4

Page Range: 697-706

Description:

The objective of this study was to rank Limousin sires by their different breeding values based on the weaning weight of their progeny. 205-day weaning weight record of altogether 18746 purebred and crossbred calves sired by breeding bulls of the mentioned breed were used for the estimation. Calves were belonging to three different groups by their genotype. Three different BLUP animal models were used for the estimation. According the results the direct heritability (h2) estimates of 205-day weight ranged between 0.49 and 0.59, while that of the maternal heritabilityd(h2) between m 0.24 and 0.45. The estimated breeding value of the given sires differed by the genotype (purebred or crossbred) of their progeny calves and the method of estimation. Also, there were differences in the rank of the sires depending on the genotype of their progeny, as well as the estimation methods.

Open Access: Yes

DOI: 10.5513/JCEA01/21.4.2821

Fuzzy rule base model identification by bacterial memetic algorithms

János Botzheim László Gál Laszlo T. Koczy

Publication Name: Studies in Computational Intelligence

Publication Date: 2009-09-03

Volume: 222

Issue: Unknown

Page Range: 21-43

Description:

Fuzzy systems have been successfully used in the area of controllers for a long time. The Mamdani method is one of the most popular inference systems for practical applications. The main problem of Mamdani-type inference system and other fuzzy logic based controllers is how to gain the fuzzy rules the inference system based on. Several approaches have been proposed for automatic rule base identification. The bacterial type evolutionary algorithms have been successfully applied for solving this task. These algorithms are based on the Pseudo-Bacterial Genetic Algorithm and are supplied with operations and methods (e.g. the Levenberg-Marquardt method) to complete their task more efficiently. The goal is to create more accurate fuzzy rule bases from input-output data sets as quickly as possible. In this work, we summarize the bacterial type evolutionary algorithms used for fuzzy rule base identification. © 2009 Springer-Verlag Berlin Heidelberg.

Open Access: Yes

DOI: 10.1007/978-3-642-02187-9_3

Influence of welding thermal cycles on microstructure and impact toughness of high-strength steels: A gleeble simulation study

Mahmood Alhafadhi Lama Mkanna

Publication Name: Journal of Materials Research and Technology

Publication Date: 2026-05-01

Volume: 42

Issue: Unknown

Page Range: 10024-10035

Description:

Weldability of high-strength steels is strongly influenced by welding thermal cycles, particularly through their effect on heat-affected zone (HAZ) microstructure, hardness, and susceptibility to hydrogen-assisted cracking. In this study, six commercially available high-strength steels (S355MC, S500MC, S700MC, S960MC, S960QL, and S1100MC) were investigated using Gleeble physical simulation to reproduce welding thermal cycles with cooling times t8/5 = 5-20 s. Microstructural characterization, hardness measurements, and instrumented Charpy impact testing were performed and complemented by Tekken weldability tests. The results show that thermomechanically controlled processed (TMCP) steels (S355MC, S500MC, and S700MC) exhibit stable transformation behavior, maintaining consistent hardness and toughness across the investigated cooling range. In contrast, steels with yield strengths of 960 MPa and above exhibit a narrow processing window, where rapid cooling promotes the formation of hard martensitic microstructures, while slower cooling leads to grain coarsening and reduced impact toughness. Instrumented Charpy testing revealed a significant decrease in absorbed energy and crack resistance with increasing cooling time. The findings demonstrate that weldability in ultra-high-strength steels cannot be reliably assessed based on hardness alone. A combined evaluation of cooling time, microstructural evolution, hardness, and fracture behavior is required to support the selection of appropriate preheating and welding conditions.

Open Access: Yes

DOI: 10.1016/j.jmrt.2026.05.162