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Found 6278 publications

Universal autonomous robot navigation using quasi optimal path generation

Gábor Pék Peter Varlaki Áron Lászka Annamária R. Várkonyi-Kóczy

Publication Name: Icara 2009 Proceedings of the 4th International Conference on Autonomous Robots and Agents

Publication Date: 2009-06-05

Volume: Unknown

Issue: Unknown

Page Range: 458-463

Description:

Autonomous robot navigation is an important research field because these robots can solve problems where the human presence is impossible, dangerous, expensive, or uncomfortable. In this paper, a new hybrid autonomous navigation method is introduced. The algorithm is composed of visibility graph based global navigation and simple potential field based local navigation parts. It applies a new automated graph generation method which may become necessary if, because of the observed new obstacles, a new path should be generated. The quasi optimal route is found by applying the well known A* algorithm on the graph. The presented technique offers a quasi optimal universal navigation technique which can successfully be used in all, known, unknown, and dynamically changing environments. ©2009 IEEE.

Open Access: Yes

DOI: 10.1109/ICARA.2000.4804008

The kinetic energy operator in the subspaces of wavelet analysis

János Pipek Szilvia Nagy

Publication Name: Journal of Mathematical Chemistry

Publication Date: 2009-06-01

Volume: 46

Issue: 1

Page Range: 261-282

Description:

At any resolution level of wavelet expansions the physical observable of the kinetic energy is represented by an infinite matrix which is "canonically" chosen as the projection of the operator - Δ/2 onto the subspace of the given resolution. It is shown, that this canonical choice is not optimal, as the regular grid of the basis set introduces an artificial consequence of its periodicity, and it is only a particular member of possible operator representations. We present an explicit method of preparing a near optimal kinetic energy matrix which leads to more appropriate results in numerical wavelet based calculations. This construction works even in those cases, where the usual definition is unusable (i.e., the derivative of the basis functions does not exist). It is also shown, that building an effective kinetic energy matrix is equivalent to the renormalization of the kinetic energy by a momentum dependent effective mass compensating for artificial periodicity effects. © 2008 Springer Science+Business Media, LLC.

Open Access: Yes

DOI: 10.1007/s10910-008-9458-4

Health capital in the 'cis-elbanian' vs. 'trans-elbanian' grand regions: Frame disputes about framing ambiguities and misframings

Károly Varga Miklós Losoncz Sára Jeges

Publication Name: European Journal of Mental Health

Publication Date: 2009-06-01

Volume: 4

Issue: 1

Page Range: 3-26

Description:

The present study forms an operational variation of the task undertaken in the outlook paragraph of the authors' earlier article to study with the help of the Sense of Coherence (SOC) as a group property, the health and general well-being of the Hungarian national community (in an international comparison). With Hungary being the only Eastern Central European ('Trans-Elbanian') country joining the EU-project with the title Corporate Culture and Regional Embeddednes (CURE), we Hungarians tried to help achieve this goal by making the following proposal to the researchers of the five Western-European ('Cis-Elbanian') countries partaking in the project: the drastically different Health Capital level of the Grand Regions situated on the two sides of the Elbe-Leitha boundary ('centrum versus semi-periphery') should be inserted as a control variable into the original research model of the project, which has propounded the hypothesis that the interaction between the organisational culture of the corporations operating in the sample region of the individual countries and the national culture of the respective regions has had an impact on the development of the region. We have presumed that this enormous difference between the Health Capital levels can bring to light the true underlying historical-social-economical impact factors which appear to be 'cultural' when approached for the first time. The leadership of the project allowed the Hungarian team to check, beyond the qualitative research design of the project, with the quantitative method of the research, the model variation enriched with a Health Capital variable. The conclusive results thus gained anticipate an affirmation of the results achieved in the original qualitative variation of the project design and may serve as an example for the whole research team to also implement an internationally exact investigation of the effect of the Health Capital as a control variable of the cultural impact in a possible follow up. The present study displays the first, pilot study results of this research undertaking, to be implemented in our country within the frame of the CURE project, and to be transferred into the international comparison if it proves successful. These preliminary results illustrate the interdependency of the cultural dimensions and the Health Capital apprehended in a salutogenic cross section. © 2009 Akadémiai Kiadó, Budapest.

Open Access: Yes

DOI: 10.1556/EJMH.4.2009.1.1

Simulation of 2D inviscid, adiabatic, compressible flows on emulated digital CNN-UM

Sándor Kocsárdi Zoltán Nagy Árpád Csík Péter Szolgay

Publication Name: International Journal of Circuit Theory and Applications

Publication Date: 2009-05-01

Volume: 37

Issue: 4

Page Range: 569-585

Description:

In the area of mechanical, aerospace, chemical and civil engineering the solution of partial differential equations has been one of the most important problems in mathematics for a long time. In this field, one of the most exciting areas is the simulation of fluid flow, which involves for example, problems of air, sea and land vehicle motion. In this paper a CNN-UM based solver of 2D inviscid, adiabatic, compressible fluids will be presented. The governing equations are solved by using first- and second-order numerical methods. Unfortunately the necessity of the coupled multi-layered computational structure with nonlinear, space-variant templates does not make it possible to utilize the huge computing power of the analog CNN-UM chips. To improve the performance of our solution emulated digital CNN-UM implemented on FPGA has been used. Properties of the implemented specialized architecture is examined in terms of area, speed and accuracy. Copyright © 2008 John Wiley and Sons, Ltd.

Open Access: Yes

DOI: 10.1002/cta.565

Multi-level meshless methods based on direct multi-elliptic interpolation

Csaba Gáspár

Publication Name: Journal of Computational and Applied Mathematics

Publication Date: 2009-04-15

Volume: 226

Issue: 2

Page Range: 259-267

Description:

A short overview on the direct multi-elliptic interpolation and the related meshless methods for solving partial differential equations is given. A new technique is proposed which produces a biharmonic interpolation along the boundary and solves the original problem inside the domain. An error estimation is also derived. To implement the method, quadtree-based multi-level methods are used. The approach avoids the use of large, dense and ill-conditioned matrices and significantly reduces the computational cost. © 2008 Elsevier B.V. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.cam.2008.08.005

Simulation of Two-Dimensional supersonic flows on emulated-digital CNN-UM

Sándor Kocsárdi Zoltán Nagy Árpád Csík Péter Szolgay

Publication Name: Eurasip Journal on Advances in Signal Processing

Publication Date: 2009-04-09

Volume: 2009

Issue: Unknown

Page Range: Unknown

Description:

Computational fluid dynamics (CFD) is the scientific modeling of the temporal evolution of gas and fluid flows by exploiting the enormous processing power of computer technology. Simulation of fluid flow over complex-shaped objects currently requires several weeks of computing time on high-performance supercomputers. A CNN-UM-based solver of 2D inviscid, adiabatic, and compressible fluids will be presented. The governing partial differential equations (PDEs) are solved by using first- and second-order numerical methods. Unfortunately, the necessity of the coupled multilayered computational structure with nonlinear, space-variant templates does not make it possible to utilize the huge computing power of the analog CNN-UM chips. To improve the performance of our solution, emulated digital CNN-UM implemented on FPGA has been used. Properties of the implemented specialized architecture is examined in terms of area, speed, and accuracy.

Open Access: Yes

DOI: 10.1155/2009/923404

Input parameters of transdanubian clay for the hardening soil and soft soil models

Edina Koch

Publication Name: Pollack Periodica

Publication Date: 2009-04-01

Volume: 4

Issue: 1

Page Range: 93-104

Description:

In recent years, finite element modeling has become an important design tool. Advanced programs make it possible to use more complex soil models in addition to standard elasto-plastic models with Mohr-Coulomb failure criteria. These new models can follow nonlinear behavior and complicated loading sequences. The two most promising new models are: the Hardening Soil Model (HS) and the Soft Soil Model (SS). This paper focuses on the behavior of Transdanubian Clay, common in Hungary. Sampling, laboratory testing, and evaluation of data aiming at determining parameters for HS and SS models are described. Results based on oedometer tests using unloading/reloading sequences proved to be adequate for input to these models. © 2009 Akadémiai Kiadó.

Open Access: Yes

DOI: 10.1556/Pollack.4.2009.1.10

Fuzzy rule extraction by bacterial memetic algorithms

János Botzheim Cristiano L. Cabrita António E. Ruano László T. Kóczy

Publication Name: International Journal of Intelligent Systems

Publication Date: 2009-03-01

Volume: 24

Issue: 3

Page Range: 312-339

Description:

In our previous papers, fuzzy model identification methods were discussed. The bacterial evolutionary algorithm for extracting fuzzy rule base from a training set was presented. The Levenberg-Marquardt method was also proposed for determining membership functions in fuzzy systems. The combination of the evolutionary and the gradient-based learning techniques is usually called memetic algorithm. In this paper, a new kind of memetic algorithm, the bacterial memetic algorithm., is introduced for fuzzy rule extraction. The paper presents how the bacterial evolutionary algorithm can be improved with the Levenberg-Marquardt technique. © 2009 Wiley Periodicals, Inc.

Open Access: Yes

DOI: 10.1002/int.20338

Effect of emulated head-tracking for reducing localization errors in virtual audio simulation

György Wersényi

Publication Name: IEEE Transactions on Audio Speech and Language Processing

Publication Date: 2009-02-01

Volume: 17

Issue: 2

Page Range: 247-252

Description:

Virtual audio simulation uses head-related transfer function (HRTF) synthesis and headphone playback to create a sound field similar to real-life environments. Localization performance is influenced by parameters such as the recording method and the spatial resolution of the HRTFs, equalization of the measurement chain as well as common headphone playback errors. The most important errors are in-the-head localization and front-back reversals. Among other cues, small movements of the head are considered to be important to avoid these phenomena. This study uses the BEACHTRON sound card and its HRTFs for emulating small head-movements by randomly moving the virtual sound source to emulate head-movements. This method does not need any additional equipment, sensors, or feedback. Fifty untrained subjects participated in the listening tests using different stimuli and presentation speed. A virtual target source was rendered in front of the listener by random movements of 1 -7 . Experiments showed that this kind of simulation can be helpful to resolve in-the-head localization, but there is no clear benefit for resolving front-back errors. Emulation of small head-movements of 2 could actually increase externalization rates in about 21% of the subjects while presentation speed is not significant. © 2009 IEEE.

Open Access: Yes

DOI: 10.1109/TASL.2008.2006720