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Found 6374 publications

Dynamic Preisach model identification applying FEM and measured BH curve

Miklós Kuczmann

Publication Name: COMPEL the International Journal for Computation and Mathematics in Electrical and Electronic Engineering

Publication Date: 2014-01-01

Volume: 33

Issue: 6

Page Range: 2043-2052

Description:

Purpose - The purpose of this paper is to develop a viscous-type frequency dependent scalar Preisach hysteresis model and to identify the model using measured data and nonlinear numerical field analysis. The hysteresis model must be fast and well applicable in electromagnetic field simulations. Design/methodology/approach - Iron parts of electrical machines are made of non-oriented isotropic ferromagnetic materials. The finite element method (FEM) is usually applied in the numerical field analysis and design of this equipment. The scalar Preisach hysteresis model has been implemented for the simulation of static and dynamic magnetic effects inside the ferromagnetic parts of different electrical equipment. Findings - The comparison between measured and simulated data using a toroidal core shows a good agreement. A modified nonlinear version of TEAM Problem No. 30.a is also shown to test the hysteresis model in the FEM procedure. Originality/value - The dynamic model is an extension of the static one; an extra magnetic field intensity term is added to the output of the static inverse model. This is a viscosity-type dynamic model. The fixed-point method with stable scheme has been realized to take frequency dependent anomalous losses into account in FEM. This scheme can be used efficiently in the frame of any potential formulations of Maxwell's equations.

Open Access: Yes

DOI: 10.1108/COMPEL-11-2013-0368

Parallel edge finite elementmethod to solve eddy current field problems

No authors available

Publication Name: Acta Technica CSAV (Ceskoslovensk Akademie Ved)

Publication Date: 2015-01-01

Volume: 60

Issue: 3

Page Range: 277-290

Description:

Two non-overlapping domain decomposition methods are presented and compared. They are used for parallelization of the finite element method with edge element approximation. In this case, the methods under investigation are the Schur complement method and the Lagrange multiplier based finite element tearing and interconnecting method, and their solvers. The performance of these methods and solvers is investigated in detail for two-dimensional eddy current field problems as case studies.

Open Access: No

DOI: DOI not available

Optimising Portfolio Risk by Involving Crypto Assets in a Volatile Macroeconomic Environment

Gergő Thalmeiner László Pataki Attila Bányai Tatay Tibor

Publication Name: Risks

Publication Date: 2024-04-01

Volume: 12

Issue: 4

Page Range: Unknown

Description:

Portfolio diversification is an accepted principle of risk management. When constructing an efficient portfolio, there are a number of asset classes to choose from. Financial innovation is expanding the range of instruments. In addition to traditional commodities and securities, other instruments have been added. These include cryptocurrencies. In our study, we seek to answer the question of what proportion of cryptocurrencies should be included alongside traditional instruments to optimise portfolio risk. We use VaR risk measures to optimise the process. Diversification opportunities are evaluated under normal return distributions, thick-tailed distributions, and asymmetric distributions. To answer our research questions, we have created a quantitative model in which we analysed the VaR of different portfolios, including crypto-diversified assets, using Monte Carlo simulations. The study database includes exchange rate data for two consecutive years. When selecting the periods under examination, it was important to compare favourable and less favourable periods from a macroeconomic point of view so that the study results can be interpreted as a stress test in addition to observing the diversification effect. The first period under examination is from 1 September 2020 to 31 August 2021, and the second from 1 September 2021 to 31 August 2022. Our research results ultimately confirm that including cryptoassets can reduce the risk of an investment portfolio. The two time periods examined in the simulation produced very different results. An analysis of the second period suggests that Bitcoin’s diversification ability has become significant in the unfolding market situation due to the Russian-Ukrainian war.

Open Access: Yes

DOI: 10.3390/risks12040068

Physical and numerical modelling of climate-change influenced, poorly-compacted glacial till embankments

No authors available

Publication Name: Geotechnical Engineering for Infrastructure and Development - Proceedings of the XVI European Conference on Soil Mechanics and Geotechnical Engineering, ECSMGE 2015

Publication Date: 2015-01-01

Volume: 7

Issue:

Page Range: 3911-3916

Description:

Cutting and embankment slopes are subject to seasonally changing hydraulic boundary conditions. This results in repeated wetting and drying of the soil mass, which in certain combinations of slope geometry, soil type, fabric feared to induce significant swellshrink cycles raising serviceability issues and possibly lead to extensive down-slope displacements. Since the response of infrastructure embankments is particularly relevant in light of the current global climate change, numerical and centrifuge model studies focusing on saturated overconsolidated clay earthworks - mainly representing cutting slopes - have been carried out to investigate the above mentioned effects. Some of these tests suggested that, even a slope failure may be triggered after a number of cycles due to softening of the soil. More recent centrifuge model test results of compacted glacial till embankment with more shallow slopes reviled that the observed behaviour for heavily overconsolidated steep slopes representing cutting like conditions should not be directly adopted when investigating the behaviour of poorly compacted embankments with dominant inter-granular porosity influencing both hydraulic and mechanical response of the structure. The paper thus aims to improve the understanding by undertaking series of numerical modelling and analysis using Plaxis. The input parameters for the implemented advanced hypoplastic constitutive model that could capture the small-strain nonlinearity have been determined based on earlier and more recent advanced element test results. The boundary conditions were set to match those from the centrifuge tests, and finally the model has been refined to reproduce the experienced hydraulic and mechanical behaviour.

Open Access: No

DOI: DOI not available

Application of evolutionary algorithms for energy efficient building design

János Botzheim Attila Talamon János Balázs Mihály Retek Árpád Csík Tamás Csoknyai

Publication Name: Iwaciii 2011 International Workshop on Advanced Computational Intelligence and Intelligent Informatics Proceedings

Publication Date: 2011-12-01

Volume: Unknown

Issue: Unknown

Page Range: 6

Description:

The topic of energy efficient building design is an attractive philosophy in the era of diminishing fossil energy sources drained by the ever increasing thirst of the Earth's population for energy. In this paper we propose to apply evolutionary algorithms aiding the design of energy efficient buildings. We employ a simple mathematical model involving a large number of parameters. Energy efficiency is defined in terms of these parameters through algebraic evaluations. The quasi-optimal values of the fitness function representing the level of energy efficiency are obtained by Bacterial Evolutionary Algorithms. Results indicate that in the case of a prescribed total construction cost close to 80% improvement can be achieved in terms of energy efficiency. On the other hand, if one targets a prescribed energy efficiency, more than 30% of the total construction costs can be saved by proper optimization.

Open Access: Yes

DOI: DOI not available

Numerical modeling of levees according to Eurocode 7

No authors available

Publication Name: Geotechnical Engineering for Infrastructure and Development - Proceedings of the XVI European Conference on Soil Mechanics and Geotechnical Engineering, ECSMGE 2015

Publication Date: 2015-01-01

Volume: 4

Issue:

Page Range: 2019-2024

Description:

In many European countries, flood protection and development of levees has a great importance due to ever-increasing flood levels. The final version of Eurocode 7 includes three chapters that govern the levee design. They suggest mainly conventional concepts and principles but do not provide a comprehensive design methodology for use in practice as it was formerly given in the national standards. Analytical seepage calculations used in present-day practice are based on numerous simplifying assumptions, so they often do not simulate actual conditions. The method of slices, generally used for stability analysis, is sometimes criticized for theoretical reasons. Recently, development of numerical modeling and software have employed coupled finite element analysis for mechanical and hydraulic problems. A single FEM model can apply to levee design, stability analysis, underseepage and through seepage, and analysis of seepage forces. This paper reports research results gained about modeling levees by Plaxis to meet the requirements of the Eurocode 7.

Open Access: No

DOI: DOI not available

Multi-Physics thermal analysis of permanent magnets motors with exterior rotor

No authors available

Publication Name: Civil-Comp Proceedings

Publication Date: 2015-01-01

Volume: 108

Issue:

Page Range: Unknown

Description:

This paper presents a magneto-thermal analysis of an external-rotor permanent magnet synchronous machine based on finite element method. The model developed can be used to predict the temperature distribution inside the motor during the rated operation. Electromagnetic computation is carried out with the aid of two twodimensional finite-element simulations of the cross-section of the permanent magnet motor [1]. In addition, the magnetic core losses of the stator and rotor are modelled based on the results from the electromagnetic analysis and a post-processing formula based on the loss-separation principle. To analyse the process of heat transfer in an electrical machine, empirical correlations are used to describe the convective heat transfer from the different surfaces of the permanent magnet motor. The heat transfer coefficients are determined using dimensionless numbers and the Nusselt number [2]. After the loss calculation, the temperatures of the machine are calculated using a three-dimensional finite element method. The results obtained from the model are compared with the experimental results from testing the prototype electric motor.

Open Access: No

DOI: DOI not available

Enhancement and assessment of engineering soft skills in a game-based learning environment

No authors available

Publication Name: Proceedings of the European Conference on Games-based Learning

Publication Date: 2015-01-01

Volume: 2015-January

Issue:

Page Range: 178-185

Description:

Engineering education literature shares a consensual vision of the importance of soft skills for every workplace. Despite of the growing demand for graduates with high EQ (Emotional Intelligence Quotient), one of the main challenges of the industry is the lack of soft skills, in particular, communication and negotiation skills, problem-solving skills, interpersonal skills, as well as critical and creative thinking skills. This paper investigates the enhancement of skills in a game-based learning environment, which was specifically designed to develop both hard (technical) and soft (personal) skills of engineering students through hands on experiences and observations. The acquired data is gathered using data triangulation, and it consists of self-assessments, observations, questionnaires and technical measurements. Preliminary results indicate that the environment has a significant impact on soft skill development, and show a correlation between soft-skill development and the level of motivation and self-evaluation.

Open Access: No

DOI: DOI not available

Creative cities in Central and Eastern Europe-Examining the position of Gyor from the creative and cultural aspects of this macro-region

Szabolcs Morvay Dávid Fekete

Publication Name: Regional Statistics

Publication Date: 2019-01-01

Volume: 9

Issue: 2

Page Range: 45-66

Description:

The European Union is paying increasing more attention to the creative sector, acknowledging the economic significance of the sphere and appreciating the social benefits of creative and cultural activities. Its latest innovation is the Cultural and Creative Cities Monitor (CCCM), which shows the creative vibrancy of 168 European cities, thus enabling a comparison and ranking in terms of different creative and cultural aspects. Gyor has been included in this platform's list besides Budapest, Pecs, and Szeged. In this study the creative position of Gyor, in relation to similar mid-sized Central and Eastern European cities is examined, thus estimating the creative potential of Gyor. The analysis enables us to observe the elements and indicators of a creative city that are used to measure and show creativity. Exploring the city's strengths and weaknesses provides guidance as the CCCM annually renews its evaluation and changes the ranking. With conscious initiatives Gyor may become more creative, both internationally and locally. Based on the CCCM scores Gyor has numerous strengths: favourable geographic location, adequate amount of cultural offerings, strong economic potential, cultural vibrancy, and a high level of participation in cultural life. However, the city has weak features too, that require strengthening. The aim is for the cities to become more creative, but this requires analysis from the creative and cultural aspects. We offer an analysis that focuses on Hungarian cities, on our macro-region and on the creative and cultural elements of these cities.

Open Access: Yes

DOI: 10.15196/RS090209