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Found 6278 publications

On the positivity step size threshold of Runge-Kutta methods

Zoltán Horváth

Publication Name: Applied Numerical Mathematics

Publication Date: 2005-05-01

Volume: 53

Issue: 2-4

Page Range: 341-356

Description:

In the first part of this paper we determine the largest step size of Runge-Kutta (RK) methods for which the corresponding numerical approximations are positive (component-wise non-negative) for arbitrary positive initial vector, whenever the underlying initial value problem (IVP) possesses the related positivity preserving property. We prove that step size thresholds for certain classes of positive IVPs guaranteeing positivity that we derived in a former paper are strict for irreducible and non-confluent RK methods. Investigating the strict positivity step size thresholds we can see that these are rather small if at all positive: often they are, roughly speaking, inverse proportional to the Lipschitz constant of the problem. However, for certain (stiff) IVPs with some particular initial vectors, e.g., for some "smooth" vectors in semi-discretized diffusion problems, we experience preservation of positivity with much larger step sizes than the strict positivity step size threshold. To catch this phenomenon, in the second part of the paper we construct positively invariant sets of positive vectors and derive step size thresholds for the discrete version of the positive invariance. The resulting threshold for discrete positive invariance is, roughly speaking, inverse proportional to the one-sided Lipschitz constant only and is shown in good accordance with some displayed computational experiments. © 2004 IMACS. Published by Elsevier B.V. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.apnum.2004.08.026

Optimal life-time maintenance policy and deterioration process

András Bakó Lajos Tóth

Publication Name: Ines 05 IEEE 9th International Conference on Intelligent Engineering Systems Proceedings

Publication Date: 2005-01-01

Volume: 2005

Issue: Unknown

Page Range: 229-232

Description:

With the recognition that the engineering structures maintenance and repair needs far exceed the rescourses available to adress these needs, many firms have to turned to the development of ESMS (Enginnering Structures Management System) as a method to improve the allocation of these limited resources and the condition of their engineering structures. The ESMS is based on performance modelingbecause of without the actual condition of the structures and the future deterioration process any model could not be build up. The paper provides an overviev of the need for ESMS and the posibble description of the performance modeling. © 2005 IEEE.

Open Access: Yes

DOI: 10.1109/INES.2005.1555163

Hawkes processes: some key ideas, links to neuroscience and system identification

Dániel Fabó György Perczel Loránd Erőss Zsuzsanna Vágó László Gerencsér

Publication Name: Communications in Information and Systems

Publication Date: 2021-01-01

Volume: 21

Issue: 3

Page Range: 385-413

Description:

The primary objective of the present paper is to provide a brief survey of basic ideas and some key results of the theory of Hawkes processes that may serve as an interface for multidisciplinary research between mathematics and neurosciences, with hints to epidemiology. The class of Hawkes processes is considered as an appropriate model to describe the pattern of neuronal firing, see [56] [38]. As such, it is a prime candidate for detecting changes in brain activity, and consequently to predict epileptic seizures. Most of the advanced results will be presented via simple examples. In addition, we elaborate on links between the theory of Hawkes processes and linear stochastic systems, in particular system identification. A few new results in this context will be also presented with the outline of their proofs.

Open Access: Yes

DOI: 10.4310/cis.2021.v21.n3.a4

Quantifying the overlooked groundwater component in the water budget of a shallow soda lake in Hungary amidst climate change concerns

Anita Erőss Ádám Tóth Péter Szabó Petra Baják András Csepregi Katalin Hegedűs-Csondor Máté Chappon

Publication Name: Journal of Hydrology Regional Studies

Publication Date: 2024-12-01

Volume: 56

Issue: Unknown

Page Range: Unknown

Description:

Study region: Lake Velence. Study focus: Soda lakes are extreme habitats whose special hydrochemical characteristics can partly be explained by groundwater inflow. The relationship between groundwater and Lake Velence has never been properly investigated. A significant decrease in the lake's level in recent years urged an evaluation of the components of the lake's water budget, including groundwater as well. A 3D transient numerical groundwater flow simulation, using Visual MODFLOW, was performed between 1990 and 2021 to evaluate the lake's relationship with groundwater and quantify the groundwater discharge into the lake. To assess future lake level changes until 2050, six lake level simulations were run based on three different regional climate models and two global warming scenarios (RCP2.6 and RCP8.5). New hydrological insights for the region: Our results showed that groundwater inflow accounts for up to 12 % of the total annual inflow into Lake Velence. It has been numerically shown that precipitation and evaporation are the primary drivers of lake level changes, meaning that the variation of these two parameters will impact the lake's future. As for the future lake level changes, the RCP2.6 scenario resulted in an increase of 11 cm, while the RCP8.5 scenario led to a decrease of 30 cm compared to the observed annual average lake level until 2050. Our results emphasize the importance of integrating soda lakes into topography-driven groundwater flow systems to develop climate change adaptation strategies.

Open Access: Yes

DOI: 10.1016/j.ejrh.2024.101961

Frame Design Using Nonprismatic Members – Satisfying the Need for Speed

No authors available

Publication Name: Proceedings of the Annual Stability Conference Structural Stability Research Council, SSRC 2023

Publication Date: 2023-01-01

Volume:

Issue:

Page Range: Unknown

Description:

This paper discusses a combination of best practices and procedures from recent work in Europe and the US, providing rational and economical calculations addressing the complexities associated with frame design using nonprismatic members. Recommendations are provided in the context of US design practice. A primary objective is to achieve maximum simplicity, transparency, and design speed while facilitating rigor of the underlying calculations. The paper provides several focused examples illustrating the recommended design verification procedures.

Open Access: No

DOI: DOI not available

Enhancing decision-making with linear diophantine multi-fuzzy set: application of novel information measures in medical and engineering fields

Dragan Pamucar Nasreen Kausar J. Vimala Jeevitha Kannan Vladimir Simic

Publication Name: Scientific Reports

Publication Date: 2024-12-01

Volume: 14

Issue: 1

Page Range: Unknown

Description:

This study offers a comprehensive analysis of novel information for linear diophantine multi-fuzzy sets and illustrates its applications in practical scenarios. We introduce innovative similarity metrics tailored for linear diophantine multi-fuzzy sets, including Cosine similarity, Jaccard similarity, and Exponential similarity. Additionally, we propose Entropy, Inclusion, and Distance measures, providing a robust theoretical foundation supported by developed theorems that explain the interactions between these metrics. The practical implications of these theoretical advancements are demonstrated through various case studies. Specifically, we apply the similarity measures to predict preeclampsia, a severe condition affecting pregnant women, showcasing their potential in medical diagnostics. The entropy measure is used to identify the optimal materials manufacturing method for medical surgical robots, underscoring its importance in ensuring patient safety and the effectiveness of medical procedures. Furthermore, the inclusion measure is employed in pattern recognition tasks, highlighting its utility in complex data analysis. The comparative and superiority analysis shows the effectiveness of our research. The novel aspect of this study is the implementation of information metrics for LDMFS. These efforts aim to enhance the impact and practical applicability of linear diophantine multi-fuzzy sets, fostering innovation and improving outcomes across multiple fields.

Open Access: Yes

DOI: 10.1038/s41598-024-79725-0

The business behaviour of representatives of small-and medium-sized enterprises in cross-cultural interaction situations

Julia Szoke

Publication Name: Tarsadalomkutatas

Publication Date: 2014-01-01

Volume: 32

Issue: 2

Page Range: 162-175

Description:

In the present paper based on the database of our own research from 2012 we examine with the help of some dimensions of national culture how the business behaviour of representatives of small-and medium-sized enterprises (henceforth SMEs) can be characterised in cross-cultural interaction situations. Previous pieces of research (e.g. Hofstede 1980, Bartlett-Ghoshal 1990) have already verifi ed that the norms, habits and behaviour patterns learnt as part of national culture strongly influence the behaviour of the members of the society therefore the business behaviour of employees as well, however, according to our hypothesis the business behaviour of representatives of SMEs is not unifi ed in cross-cultural interaction situations but can be subdivided into different categories. One novelty of our paper is that our research was concentrated on a geographical area since the sample included only representatives of Hungarian SMEs from the three counties of West-Transdanubian region with the condition that they participate in cross-cultural business relations with Austrian partner. The other novelty of the research is that the business behaviour of the respondent representatives was analysed by using some national culture dimensions of three researchers (Hofstede 1980, Trompenaars 1995, Hall 1975 and 1990), but based on the fi ndings the culture dimensions of a fourth researcher, Gesteland (2005) were outlined from the data. In our paper we fi rst introduce the theoretical background of the research, then we draw up its methodology, and fi nally as a result of our research we present the business behaviour of the representatives of SMEs from the examined region in cross-cultural interaction situations and its characteristics.

Open Access: Yes

DOI: 10.1556/Tarskut.32.2014.2.5

Novel communication services based on ENUM technology

Miklós F. Hatwágner T. Heckenast Agnes Varga N. Varjasi B. Benyo K. Kovacs

Publication Name: Ines 05 IEEE 9th International Conference on Intelligent Engineering Systems Proceedings

Publication Date: 2005-01-01

Volume: 2005

Issue: Unknown

Page Range: 217-220

Description:

ENUM is the short name for a protocol for connecting resources of telecommunication and the Internet to one another. It specifies a rule that makes it possible to relate a domain to a telephone number without any risk of ambiguity. This domain can then be used to identify various communication services like fax, mobile radio, voice-mail systems, e-mail addresses, IP telephony addresses, web pages, GPS coordinates, call diverts or unified messaging. Several countries in the world examine the possibilities of the use of ENUM in national trials. Recently two Hungarian universities and an Internet service provider established a research project aiming the development of ENUM based communication services. In Hungary we have to deal not only with the questions of creating and providing the technological background, but also with the business aspects of ENUM based service development. The article will firstly give an overview about the ENUM itself. Then it will deal with ENUM services and business models. After that we discuss the situation of ENUM in different European countries. It will present the planned and accomplished ENUM based services in these countries. Then we are going to give the aims of the project in Hungary, which is led by the Szechenyi Istvan University in Gy6r. In setting these aims we can rely on the projects of other countries, and learn from them. © 2005 IEEE.

Open Access: Yes

DOI: 10.1109/INES.2005.1555160

Design thinking for innovation in 3D VR over-voltage protection with memristor

Gyorgy Elmer Zoltan Kvasznicza Ildiko Perjesi-Hamori Ildiko Horvath

Publication Name: 11th IEEE International Conference on Cognitive Infocommunications Coginfocom 2020 Proceedings

Publication Date: 2020-09-23

Volume: Unknown

Issue: Unknown

Page Range: 417-424

Description:

This paper shows an example of CogInfoCom as during analyses the operation of a memristor in a real 3D VR based teaching. This paper looks at the possibility of the application of a macroscopic memristor (MR), not yet available, combined with a spark gap for over-voltage protection purposes. During teaching the memristor as a disruptive technologies the lecturers and the students do a close cooperative work in the 3D VR space, using several mathematical softwares for analyzing of not yet avaliable memristor, so the humans and ICT are not separable on cognitive level. In this 3D VR education the cooperation of the intelligent systems with humans help to analyse, systemize the information and create new information. Memristors will possibly find applications in the field of electromagnetic compatibility, specifically in over-voltage protection, so it is timely to include it in the curriculum of electrical engineering education in BsC level. The examination of a physically non-existent memristor is made possible by 3D VR space and mathematical and infocommunication softwares. So, presenting another cost-effective opportunity for the educational applicability of VR.

Open Access: Yes

DOI: 10.1109/CogInfoCom50765.2020.9237879