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Found 6278 publications

Nonlinear two-dimensional motional finite element modeling of a Rotational eddy current field problem

Miklós Kuczmann Daniel Marcsa

Publication Name: Przeglad Elektrotechniczny

Publication Date: 2009-12-01

Volume: 85

Issue: 12

Page Range: 110-113

Description:

Rotational eddy current field problems with nonlinear effect can be solved by different potential formulations combining motion voltage term. The potential formulations are the motional Az.ast; - A - potential formulation and the motional T,φ - φ - potential formulation taking the nonlinearity of the material into account. The nonlinearity has been handled by the fixed point iteration technique (FPT). The paper presents and compares these formulations through the modified version of TEAM Problem No. 30a, which contains two induction motors.

Open Access: Yes

DOI: DOI not available

Vector hysteresis measurement and simulation

Miklós Kuczmann

Publication Name: Przeglad Elektrotechniczny

Publication Date: 2009-12-01

Volume: 85

Issue: 12

Page Range: 92-95

Description:

The paper presents a Preisach model of hysteresis to simulate the vector hysteresis properties of ferromagnetic materials. The vector behavior has been studied using a single sheet tester with a round shaped specimen at low frequency, and the magnetic flux density vector has been controlled. 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 to study numerically the measurement system.

Open Access: Yes

DOI: DOI not available

Optimal die design in extrusion process using adaptive finite element method

Lotfi Abdelhakim G. Y. Molnarka

Publication Name: Aip Conference Proceedings

Publication Date: 2009-11-26

Volume: 1168

Issue: Unknown

Page Range: 324-328

Description:

In this work, a method for calculation of the optimal shapes of axisymmetrical converging dies by an adaptive finite element method is presented. The shape optimization problem considered in this paper is to find the best shape of the die such that the flow rate will be uniform at the die exit.The optimization problem is to minimize an objective function by varying a part of boundary (ie: the shape of die) subject to constraints imposed by the metal forming problem. In this method, the B-spline functions allow us to determine the shape of the die, using its control points as design variables. An adaptive solution procedure is adapted to control the error due to the finite element approximation. The mesh adaptation is performed using the Zienkiewicz - Zhu (Z2) type error estimator. © 2009 American Institute of Physics.

Open Access: Yes

DOI: 10.1063/1.3241460

The improvement of an existing fuzzy logic rule base for the treatment and simulation of conflicts in the dispositional tasks of a railway traffic control center

Tibor Héray Márk Farkas László T. Kóczy

Publication Name: Proceedings 2009 3rd International Workshop on Soft Computing Applications Sofa 2009

Publication Date: 2009-11-25

Volume: Unknown

Issue: Unknown

Page Range: 203-207

Description:

The paper considers a railway timetable related problem in a simplified form, generated by the delay of one or several incoming trains at a given station. These incoming train delays are either automatically generated or manually entered. Usually there are connecting trains in the timetable, especially in up to date periodic timetables and thus incoming delays might indicate the necessity of introducing a delay with connecting outgoing trains. A hierarchical fuzzy rule base is applied in order to determine the optimal outgoing delay, taking also usual restrictions into consideration. The delays of the incoming trains are modeled by independent exponential distributions and a software simulation is built around the existing rule base. The behavior of the hierarchical fuzzy rule base and the pertinence of the outgoing delay is a subject of further investigation. The delays are also updated periodically that makes the recalculation of outgoing delays necessary from time to time. 1 © 2009 IEEE.

Open Access: Yes

DOI: 10.1109/SOFA.2009.5254850

Utility of time factor in logistic optimization

Peter Foldesi Edit Süle

Publication Name: Proceedings 2009 3rd International Workshop on Soft Computing Applications Sofa 2009

Publication Date: 2009-11-25

Volume: Unknown

Issue: Unknown

Page Range: 209-214

Description:

The paper deals with the investigation of the critical factor of the supply chain, with regards to time. The literature review can give a background to understand and handle the reasons and consequences of the growing importance of time. It analyses the time- and place-value of products and it evaluates time by showing theoretical functions as well. By using utility functions to represent the value of various delivery-times for the different participants in the supply chain, including the final customers, it proves through the Kano-model, that the choices, behaviour and willingness of payment of time-sensitive and non time-sensitive consumers are different for varying lead times, so for optimization soft computing techniques must be applied. © 2009 IEEE.

Open Access: Yes

DOI: 10.1109/SOFA.2009.5254851

Function approximation capability of a novel fuzzy flip-flop based Neural Network

László Gál Rita Lovassy László T. Kóczy

Publication Name: Proceedings of the International Joint Conference on Neural Networks

Publication Date: 2009-11-18

Volume: Unknown

Issue: Unknown

Page Range: 1900-1907

Description:

The function approximation capability of various connectionist systems has been one of the most interesting problems. A method for constructing Multilayer Perceptron Neural Networks (MLP NN) with the aid of fuzzy operations based flip-flops able to approximate single and multiple variable functions is proposed. This paper introduces the concept of fuzzy flip-flop based neural network, particularly by deploying three types of fuzzy flip-flops as neurons. A comparative study of feedbacked fuzzy J-K and two kinds of fuzzy D flip-flops used as neurons, based on fuzzy algebraic, Yager, Dombi, Hamacher and Frank operations is given. Simulation results are presented for several test functions. © 2009 IEEE.

Open Access: Yes

DOI: 10.1109/IJCNN.2009.5178849

A computational model for inference chains in expert systems

Jozsef Sziray

Publication Name: Proceedings 2009 International Conference on Intelligent Engineering Systems Ines 2009

Publication Date: 2009-11-02

Volume: Unknown

Issue: Unknown

Page Range: 183-188

Description:

This paper deals with the calculations performed in the reasoning process of rule-based expert systems, where inference chains are applied. It presents a logic model for representing the rules and the rule base of a given system. Also, the fact base of the same expert system is involved in the logic model. The proposed equivalent representation manifests itself in a logic network. After that, a four-valued logic algebra is introduced. This algebra is used for the calculations where forward chaining is carried out. Next, the notion of line-value justification is described. This operation is applied in the backward chaining process, also on the base of the previously introduced four-valued logic. The paper describes two exact algorithms which serve for the forward and backward chaining processes. These algorithms make it possible to be implemented by a computer program, resulting in an efficient inference engine of an expert system. The achieved result enhances the reliability and usability of the intelligent software systems which is extremely important in embedded environments. ©2009 IEEE.

Open Access: Yes

DOI: 10.1109/INES.2009.4924759

Special network algorithms with gains

Tamás Hartványi András Bakó István Szuts

Publication Name: Proceedings 2009 International Conference on Intelligent Engineering Systems Ines 2009

Publication Date: 2009-11-02

Volume: Unknown

Issue: Unknown

Page Range: 155-158

Description:

Several optimalization algorithms have been proposed for the solution the minimal and the multiterminal minimal path of a network having cost (distance) function. In this paper we present these algorithms in a special network in which on the edges a gain function is given. On the edge (x,y) of the network a t(x,y) transportation cost is defined. In the course of the transportation on the edge (x,y) the goods loose a part of there weight. If one unit of goods is transported from point x to point y then k(x,y) unite of goods arrive at point y, where 0

Open Access: Yes

DOI: 10.1109/INES.2009.4924754

Half-magnitude extensions of resolution and field of view in digital holography by scanning and magnification

Lotfi Abdelhakim Attila Tibor Nagy István Harmati Béla Ráczkevi György Molnar Dezsö Szigethy Attila Nagy G. Y. Molnarka Venczel Borbély Ferenc Gyímesi Aladar Czitrovszky Zoltán Füzessy

Publication Name: Applied Optics

Publication Date: 2009-11-01

Volume: 48

Issue: 31

Page Range: 6026-6034

Description:

Digital holography replaces the permanent recording material of analog holography with an electronic light sensitive matrix detector, but besides the many unique advantages, this brings serious limitations with it as well. The limited resolution of matrix detectors restricts the field of view, and their limited size restricts the resolution in the reconstructed holographic image. Scanning the larger aerial hologram (the interference light field of the object and reference waves in the hologram plane) with the small matrix detector or using magnification for the coarse matrix detector at the readout of the fine-structured aerial hologram, these are straightforward solutions but have been exploited only partially until now. We have systematically applied both of these approaches and have driven them to their present extremes, over half a magnitude in extensions. © 2009 Optical Society of America.

Open Access: Yes

DOI: 10.1364/AO.48.006026