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Found 6278 publications

Supersonic flow simulation on IBM cell processor based emulated digital cellular neural networks

Sándor Kocsárdi Zoltán Nagy András Kiss Árpád Csík

Publication Name: Proceedings IEEE International Symposium on Circuits and Systems

Publication Date: 2009-10-26

Volume: Unknown

Issue: Unknown

Page Range: 1225-1228

Description:

In the area of mechanical, aerospace, chemical and civil engineering the solution of partial differential equations (PDEs) has been one of the most important problems of 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 engineering applications the temporal evolution of non-ideal, compressible fluids is quite often modeled by the system of Navier-Stokes equations. They are a coupled set of nonlinear hyperbolic partial differential equations and form a relatively simple, yet efficient model of compressible fluid dynamics. 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 Cellular Neural Network Universal Machine (CNN-UM) chips. To improve the performance of our solution emulated digital CNN-UM implemented on IBM Cell Broadband Engine has been used. The goal is to perform the operations with the highest possible parallelism. ©2009 IEEE.

Open Access: Yes

DOI: 10.1109/ISCAS.2009.5117983

Fuzzy communication and motion control by fuzzy signatures in intelligent mobile robots

Tamás D. Gedeon Áron Ballagi László T. Kóczy

Publication Name: Studies in Computational Intelligence

Publication Date: 2009-10-26

Volume: 241

Issue: Unknown

Page Range: 147-164

Description:

This paper presents two examples for the deployment of fuzzy signatures in the field of intelligent mobile robots. The first shows a complex lateral drift control method base on fuzzy signatures. This method considers the motion system of the robot as a whole, unlike as simple parts of a complex system. The state space is written down by fuzzy signatures which add up flexibility, adaptability and learning ability to the system. In the second experiment a new communication approach is investigated for intelligent cooperation of autonomous mobile robots. Effective, fast and compact communication is one of the most important cornerstones of a high-end cooperating system. In this paper we propose a fuzzy communication system where the codebooks are built up by fuzzy signatures. We use cooperating autonomous mobile robots to solve some logistic problems. © 2009 Springer-Verlag Berlin Heidelberg.

Open Access: Yes

DOI: 10.1007/978-3-642-03633-0_9

The value of routine second-look endoscopy in the management of the acute gastroduodenal ulcer bleeding

Tibor Kárász Márta Jánoki Hussam Saleh Istvan Racz Nora Dancs Katalin Szocs Andrea Szabó Zoltán Horváth Mihaly Csöndes

Publication Name: Orvosi Hetilap

Publication Date: 2009-10-01

Volume: 150

Issue: 42

Page Range: 1932-1936

Description:

The role of routine second-look endoscopy in the management of patients with acute peptic ulcer bleeding is controversial. A more precise identification of higher risk patient group, based on both clinical and endoscopic criteria, is needed to determine whether there are high-risk patients who may benefit from this management strategy. Aim: Or aim was to find out whether scheduled second-look endoscopy has any beneficial effect in the clinical outcome. Methods: Both endoscopic and clinical data were analyzed in 274 acute gastroduodenal ulcer bleeding patients. The need for repeated endoscopic haemostatic intervention was used as a measure to evaluate the potential beneficial effect of the second look endoscopy. Patients were categorized according to the Forrest classification detected during the emergency endoscopy. Results: In the subgroup of actively bleeding patients (Forrest Ia, Ib) a second endoscopic haemostasis was performed in 23.8% of cases. In the patient subgroup with visible vessel ulcers (Forrest IIa) and in those with adherent clot covered ulcers (Forrest IIb) the needs for a repeated haemostasis were 13.0% and 13.3% respectively. Despite the not statistically significant differences, remarkable clinical impact was noted favoring scheduled second look endoscopy in patients with initially active ulcer bleeding. Conclusion: In the light of the retrospective study results it may be concluded that the scheduled second look endoscopy strategy offers a beneficial clinical outcome for selected patients estimated to be a very high risk of re-bleeding following the initial endoscopic therapy for active bleeding.

Open Access: Yes

DOI: 10.1556/OH.2009.28725

Results of Joint Experiments and other IAEA activities on research using small tokamaks

E. Dufkova J. Brotankova M. Berta R. Dejarnac A. Fonseca A. Duarte A. Neto G. Ramos G. M. Vorobjev A. Talebitaher J. Sentkerestiova D. Dunai F. J.R. Simes B. Brotas I. El Chama Neto R. Gonzales M. Kolokoltsov I. Nedzelski D. Nurov V. Pavlov V. Soldatov B. Tl E. Sukhov D. Valcrcel I. Ďuran J. Figueiredo J. G. Ferreira B. Brotas L. Petrov A. Singh A. Czarnecka P. Carvalho N. Dreval J. Santos H. Hegazy H. Hegazy A. Sharnin P. Khorshid C. R. Gutierrez Tapia L. Ruchko G. Kirnev N. Kirneva L. A. Berni V. Vershkov A. Malaquias M. Hron A. W. Kraemer-Flecken P. Balan B. Kuteev G. Mank M. Gryaznevich L. I. Krupnik E. Del Bosco H. Figueiredo V. Budaev A. Ovsyannikov A. Melnikov H. Fernandes G. Van Oost M. Sokolov R. Gomes R. Coelho C. Silva Y. Kuznetsov J. Herrera P. Peleman J. Zajac S. Zoletnik V. Weinzettl J. Stöckel M. Nieto-Perez

Publication Name: Nuclear Fusion

Publication Date: 2009-09-21

Volume: 49

Issue: 10

Page Range: Unknown

Description:

This paper presents an overview of the results obtained during the Joint Experiments organized in the framework of the IAEA Coordinated Research Project on 'Joint Research Using Small Tokamaks' that have been carried out on the tokamaks CASTOR at IPP Prague, Czech Republic (2005), T-10 at RRC 'Kurchatov Institute', Moscow, Russia (2006), and the most recent one at ISTTOK at IST, Lisbon, Portugal, in 2007. Experimental programmes were aimed at diagnosing and characterizing the core and the edge plasma turbulence in a tokamak in order to investigate correlations between the occurrence of transport barriers, improved confinement, electric fields and electrostatic turbulence using advanced diagnostics with high spatial and temporal resolution. On CASTOR and ISTTOK, electric fields were generated by biasing an electrode inserted into the edge plasma and an improvement of the global particle confinement induced by the electrode positive biasing has been observed. Geodesic acoustic modes were studied using heavy ion beam diagnostics on T-10 and ISTTOK and correlation reflectometry on T-10. ISTTOK is equipped with a gallium jet injector and the technical feasibility of gallium jets interacting with plasmas has been investigated in pulsed and ac operation. The first Joint Experiments have clearly demonstrated that small tokamaks are suitable for broad international cooperation to conduct dedicated joint research programmes. Other activities within the IAEA Coordinated Research Project on Joint Research Using Small Tokamaks are also overviewed. © 2009 IAEA, Vienna.

Open Access: Yes

DOI: 10.1088/0029-5515/49/10/104026

Fuzzy rule base model identification by bacterial memetic algorithms

János Botzheim László Gál László T. Kóczy

Publication Name: Studies in Computational Intelligence

Publication Date: 2009-09-03

Volume: 222

Issue: Unknown

Page Range: 21-43

Description:

Fuzzy systems have been successfully used in the area of controllers for a long time. The Mamdani method is one of the most popular inference systems for practical applications. The main problem of Mamdani-type inference system and other fuzzy logic based controllers is how to gain the fuzzy rules the inference system based on. Several approaches have been proposed for automatic rule base identification. The bacterial type evolutionary algorithms have been successfully applied for solving this task. These algorithms are based on the Pseudo-Bacterial Genetic Algorithm and are supplied with operations and methods (e.g. the Levenberg-Marquardt method) to complete their task more efficiently. The goal is to create more accurate fuzzy rule bases from input-output data sets as quickly as possible. In this work, we summarize the bacterial type evolutionary algorithms used for fuzzy rule base identification. © 2009 Springer-Verlag Berlin Heidelberg.

Open Access: Yes

DOI: 10.1007/978-3-642-02187-9_3

Comparison of the A*-A and T φ-phi; Formulations for the 2-D analysis of solid-rotor induction machines

Miklós Kuczmann Daniel Marcsa

Publication Name: IEEE Transactions on Magnetics

Publication Date: 2009-09-01

Volume: 45

Issue: 9

Page Range: 3329-3333

Description:

We present two eddy-current field potential formulations to solve rotating electrical machine problems by applying the finite-element method (FEM) using the motional ${\mbi A}^{*}{-}{\mbi A}$-potential formulation and the motional ${\mbi T}, {\bf \Phi}{-}{\bf \Phi}$-potential formulation. We use the single-phase and three-phase solid-rotor induction motors of Problem No. 30a of TEAM Workshops to compare the potential formulations. We have solved both problems in the time domain and the frequency domain. © 2009 IEEE.

Open Access: Yes

DOI: 10.1109/TMAG.2009.2022328

Fractal properties of gold, palladium and gold-palladium thin films on InP

Antal Ürmös Bernadett Varga Imre Mojzes Szilvia Nagy

Publication Name: Vacuum

Publication Date: 2009-08-25

Volume: 84

Issue: 1

Page Range: 247-250

Description:

Thermal interaction of indium phosphide (InP) bulk compound semiconductor with thin gold metal films was investigated in the course of the present work. The interaction of the InP/Au system resulted in a pattern showing fractal dimensions. The temperature dependence of the fractal parameters was investigated in a broad temperature range from 200 to 600 °C. No significant temperature dependence of the fractal dimension was observed. The same calculations will be presented for Au/InP and AuPd/InP systems. Our calculations show that the Pd-based contacts have a different behaviour than AuGe metallization where a strong temperature dependence of the fractal number was observed earlier. Another topology measure, the structural entropy is also calculated for the samples. The structural entropy is usually applied for determining the type of the localization of charge distributions, but it can also be used for generalized charges, such as the lightness of the pixels of an electron microscopy picture. © 2009 Elsevier Ltd. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.vacuum.2009.06.004

Structural entropy in detecting background patterns of AFM images

L. M. Molnár Imre Mojzes Szilvia Nagy

Publication Name: Vacuum

Publication Date: 2009-08-25

Volume: 84

Issue: 1

Page Range: 179-183

Description:

Structural entropy was developed for detecting the type of localization in charge distributions on a finite grid, especially in mesoscopic electronic systems. However, it is possible to detect and analyze superstructures, i.e., topologies consisting of more structures with different types of localization properties. In the definition of the structural entropy, the von Neumann entropy of the system is divided into two parts: first, the extension entropy, which is simply the logarithm of the occupation number; the second part is the structural entropy. On a structural entropy versus logarithm of the spatial filling factor map, the different types of localizations follow different, well-characterized curves. Spatial filling factor measures the percentage of the "filled" (i.e., high intensity) pixels of the image. An atomic force microscopy (AFM) image can be interpreted as some kind of charge distribution on a grid: after normalization, the darkness (or lightness) of the pixels fulfills all the necessary conditions. AFM image artifacts can be detected by plotting the structural entropy versus the logarithm of the spatial filling factor maps of the images. Not only the type of an added large-scale Gaussian, parabolic, exponential, or other function can be identified, but also by careful study of the curves belonging to the structures, the parameters can be detected, too. © 2009 Elsevier Ltd. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.vacuum.2009.04.025

Fractal properties of AlGeNi layers on GaAs surfaces

L. M. Molnár Bernadett Varga Imre Mojzes Szilvia Nagy

Publication Name: Vacuum

Publication Date: 2009-08-25

Volume: 84

Issue: 1

Page Range: 251-253

Description:

The thermal interactions of thin AlGe and AlNiGe layers with a bulk GaAs monocrystal were investigated. The heat treatment of these systems was carried out in the working chamber of a scanning electron microscope. The SEM pictures were analysed using a fractal mathematical technique. It was found that the surface of the samples has fractal character. No temperature dependence of the fractal dimension was observed. The samples were also studied using the structural entropy versus filling factor maps of the samples in order to find their localization properties. The SEM pictures of AlGe perform mostly as a Gaussian functions, whereas the AlNiGe samples show usually a behaviour with exponential decay. © 2009 Elsevier Ltd. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.vacuum.2009.06.005