Wersenyi G.,Szechenyi Istvan University
AES: Journal of the Audio Engineering Society | Year: 2012
Localization performance and spatial hearing abilities of blind persons are complex issues. In everyday life we rely on the "fact" that blind people can hear better, without thinking of what "better" means. Localization performance depends on many parameters such as properties of the excitation signal, environmental conditions, individual aspects, and visual influence. Our goal was to create a virtual environment aimed at helping the blind community use personal computers. In developing this environment we were concerned to cover technical and hearing related questions, as well as human factors. At first, this project included sighted subjects and basic properties of the virtual audio system and the applied HRTFs were tested. Subsequently, blind persons have been involved and comparative measurements performed using the same equipment and selected localization tasks. Twenty-eight blind person's localization performances were tested and compared with the results of 40 sighted subjects in a virtual audio environment. Blind subjects tended to be better in detecting movements in the horizontal plane around the head, localizing static frontal audio sources, and orientation in a 2-D virtual audio display. On the other hand, sighted subjects performed better identifying ascending sound sources in the vertical plane and detecting static sources in the back. In-the-head localization error rates and MAA results appeared to be about the same for both groups. The evaluation was also supported by some informal questions.
Gaspar C.,Szechenyi Istvan University
Engineering Analysis with Boundary Elements | Year: 2015
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. © 2015 Elsevier Ltd. All rights reserved.
Reti T.,Szechenyi Istvan University
Match | Year: 2012
The Zagreb indices introduced by Gutman and Trinajstić more than thirty years ago are graph-based molecular structure descriptors. The research and application of the Zagreb indices appears mainly in mathematical chemistry. In this paper we present some new inequalities related to the first and the second Zagreb indices. By introducing the notions of P-dominant graphs, and of the valency-functions of a graph, correspondences with the novel inequalities presented are discussed. In addition, we find examples characterizing the validity of Zagreb indices inequality and equalities for some particular classes of connected biregular graphs.
Harmati I.A.,Szechenyi Istvan University
Fuzzy Sets and Systems | Year: 2011
Fullér, Mezei and Várlaki defined the f-weighted possibilistic correlation coefficient as a new measure of interactivity of fuzzy numbers, which can be determined from the joint possibility distribution. At the end of their paper they formulated problems in connection with the lower limit of the f-weighted possibilistic correlation coefficient, if we know only the marginal distributions. In this paper we will discuss these problems. © 2010 Elsevier B.V. All rights reserved.
Kuczmann M.,Szechenyi Istvan University
Physica B: Condensed Matter | Year: 2011
The paper presents a Preisach model to simulate the vector hysteresis properties of ferromagnetic materials. The vector behavior has been studied using a single sheet tester with a disk-shaped specimen at low frequency. The locus of the magnetic flux density vector has been controlled by a digital measurement system. An inverse vector Preisach hysteresis model has been developed and identified by applying the measured data. Finally, the inverse model has been inserted into a finite element procedure through the fixed point technique and the reduced magnetic scalar potential formulation to simulate the measurement system. The applicability of the measurement system as well as the developed model has been proven by comparing measured and simulated results. © 2011 Elsevier B.V. All rights reserved.