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Found 6289 publications

A regularized multi-level technique for solving potential problems by the method of fundamental solutions

Csaba Gáspár

Publication Name: Engineering Analysis with Boundary Elements

Publication Date: 2015-06-03

Volume: 57

Issue: Unknown

Page Range: 66-71

Description:

The method of fundamental solutions is investigated in the case when the source points are located along the boundary of the domain of the original problem and coincide with the collocation points. The appearing singularities are eliminated by several techniques: by using approximate but continuous fundamental solutions (regularization) and via auxiliary subproblems to avoid the stronger singularities that appear in the normal derivatives of the fundamental solution (desingularization). Both monopole and dipole formulations are investigated. A special iterative solution algorithm is presented, which converts the original (mixed) problem to a sequence of pure Dirichlet and pure Neumann subproblems. The pure subproblems can be handled efficiently by using conjugate gradients. The efficiency is significantly increased by embedding the resulting method in a natural multi-level context. At the same time, the problem of the use of highly ill-conditioned matrices is also avoided.

Open Access: Yes

DOI: 10.1016/j.enganabound.2014.05.002

A novel multimodal communication framework using robot partner for aging population

János Botzheim Dalai Tang Bakhtiar Yusuf Chee Seng Chan Naoyuki Kubota

Publication Name: Expert Systems with Applications

Publication Date: 2015-06-01

Volume: 42

Issue: 9

Page Range: 4540-4555

Description:

In developed country such as Japan, aging has become a serious issue, as there is a disproportionate increasing of elderly population who are no longer able to look after themselves. In order to tackle this issue, we introduce human-friendly robot partner to support the elderly people in their daily life. However, to realize this, it is essential for the robot partner to be able to have a natural communication with the human. This paper proposes a new communication framework between the human and robot partner based on relevance theory as the basis knowledge. The relevance theory is implemented to build mutual cognitive environment between the human and the robot partner, namely as the informationally structured space (ISS). Inside the ISS, robot partner employs both verbal as well as non-verbal communication to understand human. For the verbal communication, Rasmussen's behavior model is implemented as the basis for the conversational system. While for the non-verbal communication, environmental and human state data along with gesture recognition are utilized. These data are used as the perceptual input to compute the robot partner's emotion. Experimental results have shown the effectiveness of our proposed communication framework in establishing natural communication between the human and the robot partner.

Open Access: Yes

DOI: 10.1016/j.eswa.2015.01.016

Optimum control strategy for PMSM in field-weakening region by constant power

I. Szenasy Zoltán Szeli Z. Varga

Publication Name: Electrical Systems for Aircraft Railway and Ship Propulsion Esars

Publication Date: 2015-05-04

Volume: 2015-May

Issue: Unknown

Page Range: Unknown

Description:

For electric vehicles an applied control of PMSM is the flux weakening operation for extending the region over nominal speed on nominal voltage. This paper deals with these questions and its impacts. Proved methods increase the torque angle and the d axis directed component of the stator current vector reduces the main flux, but the eddy current loss developing in magnets became significant. These impacts and their reduction need several investigations. This paper preents the possibilities and limits of flux-weakening for a given PMSM, and gives a usable optimum control strategy on nominal power's region by varied speeds.

Open Access: Yes

DOI: 10.1109/ESARS.2015.7101435

Ambient concentrations of PM10, PM10-bound polycyclic aromatic hydrocarbons and heavy metals in an urban site of Győr, Hungary

Andrea Szabó Nagy József Erdős János Szabó

Publication Name: Air Quality Atmosphere and Health

Publication Date: 2015-04-01

Volume: 8

Issue: 2

Page Range: 229-241

Description:

An assessment of the air quality of Győr (Hungary) was performed by determining the ambient concentrations of PM10, PM10-bound polycyclic aromatic hydrocarbons (PAHs) and regulated heavy metals (Pb, Cd, As and Ni) in the period of 2008−2012. The PM10 concentrations ranged from 7.90 to 119.14 μg/m3 with the mean value of 34.94 μg/m3. On average, the total PAHs (sum of the concentrations of 18 individual PAH compounds) and the four metals contents in the PM10 fraction amounted to 0.04 and 0.06 %, respectively. The total PAH concentrations ranged from 0.29 to 88.30 ng/m3, which were predominated by intermediate and high molecular weight PAHs. Higher concentrations of both PM10 and PAHs were detected in samples collected in the heating seasons. The mean metallic concentrations calculated for the 5-year sampling period were found in decreasing order of Pb (14.47 ng/m3), Ni (3.73 ng/m3), As (0.64 ng/m3) and Cd (0.60 ng/m3). Very little seasonal variation was observed in metal concentrations. Moreover, the comparison of the PM10, bezo[a]pyrene (BaP) and heavy metal concentrations determined with other Hungarian and European urban sites and the limit or target values for health protection has revealed that the air quality of Győr and other Hungarian cities for the above pollutants generally corresponds to the EU average. It is important to reduce PM10 and BaP pollution to concentrations lower than those specified in current legislation. However, the Hungarian cities have excellent air quality with respect to heavy metals.

Open Access: Yes

DOI: 10.1007/s11869-015-0318-7

The analysis of injection molding defects caused by gate vestiges

Norbert Krisztián Kovács A. Suplicz J. G. Kovacs Tamás Tábi Béla Zink H. Hargitai Ferenc Szabó

Publication Name: Express Polymer Letters

Publication Date: 2015-04-01

Volume: 9

Issue: 4

Page Range: 394-400

Description:

Issues of product safety are the most serious problems of an injection molded product due to their risk to human health. Such a safety problem can be the needle-shaped vestige at the gate zone of injection molded products, called a gate vestige. Only observations of the formation of gate vestiges can be found in the literature, but the processing parameters influencing their dimensions, especially their height have not been studied yet. Our goal was to study the effect of various injection molding processing parameters and gate constructions on gate vestige formation.

Open Access: Yes

DOI: 10.3144/expresspolymlett.2015.37

Road patterns of housing estates in Hungary

Pál Hegyi

Publication Name: Pollack Periodica

Publication Date: 2015-04-01

Volume: 10

Issue: 1

Page Range: 83-92

Description:

This paper deals with the road patterns of housing estates in eight Hungarian cities. The investigation was directed to the characteristic of street networks using geographic information system. The different types of housing estates were compared using the following indicators: ratio of T and X junctions, ratio of the dead ends, average distance between nodes, connectivity index, and road density. It is concluded that according to their street network the housing estates have three periods.

Open Access: Yes

DOI: 10.1556/Pollack.10.2015.1.8

In-cylinder pressure indication of internal combustion engines for diagnostic purposes

Peter Dely István Lakatos

Publication Name: Sami 2015 IEEE 13th International Symposium on Applied Machine Intelligence and Informatics Proceedings

Publication Date: 2015-03-16

Volume: Unknown

Issue: Unknown

Page Range: 37-40

Description:

Beside onboard diagnostic methods, procedures examining the basic processes of engine operation are also of high importance in the field of vehicle diagnostics. Thermodynamic investigation of the combustion process, for instance, is excellently applicable not only for research and development but for service diagnostic purposes too. Possibilities and significance of the above tests as well as our newly developed methods are presented in the article.

Open Access: Yes

DOI: 10.1109/SAMI.2015.7061902

Numerical investigation of heat transfer in air cooled permanent magnet electrical machines

Lotfi Abdelhakim

Publication Name: Aip Conference Proceedings

Publication Date: 2015-03-10

Volume: 1648

Issue: Unknown

Page Range: Unknown

Description:

The aim of this study is to present a magneto-thermal analysis of an external-rotor permanent magnet synchronous machine based on finite element method. The developed model can be used to predict temperature distribution inside the studied motor during the rated operation. Electromagnetic computation is carried out with the aid of two 2D finite-element (FE) simulations on the cross-section of the PM motor. 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. After the loss calculation, the temperatures of the machine are calculated by using 3D finite element method. The results obtained by the model are compared with experimental results from testing the prototype electric motor.

Open Access: Yes

DOI: 10.1063/1.4913164

Integral operators in relation to the HOSVD-based canonical form

András Rövid Peter Varlaki Lászlõ Szeidl

Publication Name: Asian Journal of Control

Publication Date: 2015-03-01

Volume: 17

Issue: 2

Page Range: 459-466

Description:

This paper describes the relation of the higher order singular value decomposition (HOSVD) based canonical form to the Hilbert-Schmidt type integral operators. This connection between the canonical form of f(x) and the integral operators determined by function f(x) is important; on the one hand it gives a new aspect for the consideration of LPV models, and on the other hand it allows for the approximation of eigenfunctions and integral operators based on a numerical reconstruction of the canonical form.

Open Access: Yes

DOI: 10.1002/asjc.1017