Search in Publications

Found 6334 publications

Fuzzy Cognitive Maps: Mathematical Challenges

István A. Harmati

Publication Name: Studies in Fuzziness and Soft Computing

Publication Date: 2024-01-01

Volume: 427

Issue: Unknown

Page Range: 95-103

Description:

Although the applications of fuzzy cognitive maps cover a wide variety of scientific and engineering fields, the deep theoretical analysis of their behaviour has a much more weaker literature. In this chapter, first we introduce a more compact description of the updating rule, which makes the further mathematical investigations easier. Then several examples of different qualitative behaviour are shown, highlighting the importance of the strict mathematical discussion of this problem. Finally, the main mathematical factors regarding the behaviour of fuzzy cognitive maps and its extensions will be introduced.

Open Access: Yes

DOI: 10.1007/978-3-031-37959-8_8

Experimental results of sliding and welding tests in a novel construction method for steel-concrete composite bridges

János Szép Daniel Gosztola

Publication Name: Fib Symposium

Publication Date: 2024-01-01

Volume: Unknown

Issue: Unknown

Page Range: 923-930

Description:

The primary objective of this study is to introduce a novel construction method used for steel-concrete composite bridges. Throughout the article, domestic and international solutions and practices will be provided for various girder-prefabricated deck slab connections, as well as construction methods for steel-concrete composite bridges. The new bridge construction technology involves the construction of a prefabricated deck slab on-site, which is moved into its final position on the main girders. During prefabrication, a stud plate is positioned within the formwork, facilitating the sliding of the deck slab elements onto the girder. The upper flange and stud plate are joined by welding following the sliding of the deck parts. The key challenge for this technology is achieving a sufficiently low friction coefficient between the stud plate and the flange using a suitable material. However, it is imperative to identify a material that can be compatible with the welded connection. Laboratory experiments were carried out to investigate the effect of materials on the friction coefficients between steel plates and the welding of the connection. The ideal material has been identified through experiments to lower the coefficient of friction to 4-8% while the welded joint can be achieved.

Open Access: Yes

DOI: DOI not available

Shear Buckling Resistance of I-Beams with Partially Stiffened Webs

G. Hajdú Hartmut Pasternak

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 358-365

Description:

This paper presents the results of laboratory tests and numerical analysis for plate girders with partial height end stiffeners. Design rules for rigid end posts and non-rigid end posts are given in EN 1993-1-5:2006 but the shear resistance of partially stiffened webs is not mentioned. The use of non-tightly fitted stiffeners is hazardous due to insufficient investigations of the real behaviour. To discover this problem parametric studies on beams with different web slenderness are examined with the usage of advanced numerical simulations. The accuracy of the EN 1993-1-5:2006 standard design rule for partially stiffened beams is also examined. The results of the numerical simulations shows that the shear buckling capacity of girders is lower than the design recommendation where the height of the web stiffener is b5% of the web height. For girders with full height stiffeners the EN 1993-1-5:2006 standard leads conservative results.

Open Access: Yes

DOI: 10.3233/ATDE240567

COMPARISON OF THE MOLDING PARAMETERS EFFECTS ON METAL INJECTION MOLDED SPECIMENS IN THE REAL EXPERIMENTAL AND SIMULATION ENVIRONMENTS

Zoltán Weltsch György Ledniczky

Publication Name: Communications Scientific Letters of the University of Zilina

Publication Date: 2024-01-01

Volume: 26

Issue: 2

Page Range: B90-B98

Description:

This article presents a technology that is not widely known. Previous research has investigated the effect of metal injection molding parameters on product shrinkage. The technology is mostly limited by the variations caused by deformation, so it is of paramount importance to focus on shrinkage. Consequently, within this study the injection molding simulations with 17-4PH type material was performed and its results were compared to the previously determined curve characters. The results obtained allow conclusions to be drawn regarding the accuracy of the simulation. Changing the parameters of the injection molding process can significantly affect the shrinkage factor. Changes in mold temperature, melt temperature and holding pressure affect the product dimensions. These parameters are also modified in the simulation setup and compared to the previous real measurements.

Open Access: Yes

DOI: 10.26552/com.C.2024.018

The Impact System of Science Centers and their Activities, in Support of Public Education and Career Guidance, during the COVID Pandemic

Attila Pongracz Szabolcs Rákosi

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2024-01-01

Volume: 21

Issue: 3

Page Range: 73-92

Description:

This paper investigates the complex impact system of the science centers, that play a key role in STEM career orientation and a draft model, for measuring these impacts. A review of the range of science centers in Hungary and an examination of the location of them provides an overview of this industry. Presentation diverse goals of science centers, their functions, along with the spatial effects of different activities, based on the comparative analysis of two institutions is presented herein. In addition to that, the paper also discusses the rural development impacts of science centers through a promising practice, and investigates innovative ways in which science center’s support public education and STEM career guidance during the COVID-19 pandemic. This research is based on the review of the current international literature on science centers. Subsequently, the Hungarian science center ecosystem is described through the analysis of public data, supplemented by the authors' personal, professional experiences in the analysis of the institutions and projects presented using a case study approach. The results show that the importance of science centers goes far beyond their function as tourist attractions, and that regular participation in their programs can enrich the knowledge base of their host city and agglomerations. The study indicates that science centers have all the required tools and methodological experience to effectively support public education in STEM fields. Finally, their ability to adapt quickly to changing circumstances, during the COVID-19 epidemic, demonstrates a “future-oriented” approach and tremendous innovation potential that are inherent in these institutions.

Open Access: Yes

DOI: 10.12700/APH.21.3.2024.3.6

Evaluating the Reliability of Hinge Definitions in Pushover Analyses: A Comparative Study of SAP2000, AxisVM

O. Kegyes-Brassai Kevin Karanja Kuria

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 291-297

Description:

This study evaluates the performance of SAP2000, and AxisVM in conducting pushover analyses, with a focus on the manual (user) definition of plastic hinges versus the automatic definitions provided by the software. Three structures, namely a single column subjected to a point load, a 2D reinforced concrete (RC) frame model, and a 3D RC model, are considered. It explores the performance of the three models in different conditions, including, application of the different software, the use of user defined (manual) hinges, and automatically generated hinges to assess their response to various analytical excitations. The need for engineers to focus on understanding the application of defining the hinge properties according to existing guidelines, including FEMA-356, ASCE 41-13/17, and Eurocodes, is highly emphasized, in addition to the existing methods as found in the literature. This is achieved by considering and comparing the capacity curves generated by the software. The results vary in some instances, especially when comparing results from user-defined and automatic hinges. It is also found that when used with precision, the results are almost similar, it is also important to use software that allows ultimate precision for better results.

Open Access: Yes

DOI: 10.3233/ATDE240558

Military Marxism: Africa’s Contribution to Revolutionary Theory, 1957–2023

Adam Mayer

Publication Name: Military Marxism Africas Contribution to Revolutionary Theory 19572023

Publication Date: 2024-01-01

Volume: Unknown

Issue: Unknown

Page Range: 1-324

Description:

Adam Mayer's Military Marxism: Africa's Contribution to Revolutionary Theory, 1957-2023 explores African Marxist theory and the intellectual merits of Afro-Maxist schools of thought to show how they have developed and impacted sub-Saharan Africa from the Cold War to the present. He also discusses the efficacy of the movements influenced by Marxism and how they are contested today. Through in-depth research, Mayer answers the following questions: Who were the African Marxist intellectuals? What happened to these intellectuals in the 1990s in NGO-administered, deindustrialized Africa? How are these theories inspiring popular rebellions and radical anti-Western military coups today? This book explores how Military Marxism, through its own rich and variegated African theory, has continued to inform and guide the practice of various political movements today.

Open Access: Yes

DOI: 10.5040/9781978747524

Natural disaster as a means of nationalising public administration: the consequences of a flood in 1879

Balázs Pálvölgyi

Publication Name: Rechtskultur

Publication Date: 2024-01-01

Volume: Unknown

Issue: Unknown

Page Range: 467-482

Description:

After the Austro-Hungarian Compromise of 1867 and the restoration of constitutionalism, the government had to resolve not only the day-to-day tasks but also the question of the role of the state, the scope for government and the role of self-government in the civil transformation. The modernisation agenda of the civic transition presupposed the development of a modern public administration, marked by the aim of ‘nationalising’, i.e. centralising public administration. The flood disaster of 1879, which devastated the city of Szeged, was a great help to Prime Minister Kálmán Tisza in achieving these goals. By shelving the institutions of county and city self-government and reconstruction after the disaster through a royal commissioner, the position of the defenders of self-government became practically comparable with the aims of the government that wanted to create a modern administration.

Open Access: Yes

DOI: DOI not available

Modernization of Windows and Doors in Protected Buildings: Possibilities and Their Environmental Impacts

T. Horváth Kitti Karolyfi András Veöreös Dóra Szalai Zsolt Szűrös Rita Rebeka Ördög

Publication Name: Chemical Engineering Transactions

Publication Date: 2024-01-01

Volume: 114

Issue: Unknown

Page Range: 1051-1056

Description:

During the renovation of protected buildings, strict regulations must be met. Buildings of different ages and protection categories require different structural solutions, including the modernization of windows and doors. In addition to heritage protection aspects, environmental awareness, sustainability, energy efficiency regulations, and the objectives of Fit for 55 and the Green Deal are given a prominent role. The research examines how the different categories of protection appear in Hungary in connection with the replacement of windows and doors and what regulations apply to their renovation. A case study of a historic building examines the effects of the interventions, with particular regard to the reduction of CO2 emissions, with the help of life cycle assessment (LCA) based on a BIM model, using machine and manual calculations. The results show that it is worth staying with the original solid wood material because changing the material – for example, to modern PVC or aluminum triple-layer windows – involves a greater environmental impact. The methodology of the analysis can be used as an analogy for the renovation of other similar buildings and can serve as a basis for issuing different tenders.

Open Access: Yes

DOI: 10.3303/CET24114176