September 2008, Volume 8, Number 3

KOVÁČOVÁ, I. — KOVÁČ, D.:
Non-Harmonic Power Measuring

KURHINEN, J. — JANATUINEN, J.:
Delay Tolerant Routing in Sparse Vehicular Ad Hoc Networks

KOLÁŘOVÁ, E.:
Instantaneous Non-Active Power Approach for Airgap Eccentricity Fault Diagnosis in Three-Phase Induction Motors

DRIF, M. — CARDOSO, A.:
The Use of Improved Root-MUSIC Frequency Estimation Method for Three Phase Induction Motor Incipient Rotor’s Faults Detection

GAMEC, J. — GAMCOVÁ, M.:
The Fast Search Motion Estimation Algorithms and their Errors

NAAMA, B. — BOUZEBOUDJA, H. — RAMDANI, Y. — CHAKER, A.
Hybrid Approach to the Economic Dispatch Problem Using a Genetic and a Quasi-Newton Algorithms

ILLÉS, Z. — PŠENÁKOVÁ, I. — HEIZLERNÉ-BAKONYI, V.:
New Perspectives of M-Learning

KLIMEŠ, C.:
Expert System Utilization for Modeling the Decision Making Processes upon Indetermination

BENDJEBBAR, M. — ZERIKAT, M.:
Contribution to the Neuro-Fuzzy Control of Voltage Induction Machine Inverter Fed

KOLLÁR, M.:
Evaluation of Real Call Set up Success Rate in GSM

HAMOUDA, M. — FLAZI, S.:
Study of the Pollution Resistance in Front of the Flashover Discharge on a Disk Model

CHOCHLÍK, M.:
Storing Dimensions and Units of Physical Quantities in a Relational Database

MIŠÁK, M.::
Mathematical Model of Electric Arc Respecting Mayr Theory in EMTP-ATP

Summary:
KOVÁČOVÁ, I. — KOVÁČ, D.:
Non-Harmonic Power Measuring [full paper]

The paper deals with the basic mathematical and computer simulation models of Hall probe. This probe is possible to utilize for converter’s non-harmonic signal measuring very easy. The benefits of such construction solution consist in galvanic isolation of evaluated signals and also in non-delaying signal processing. Functionality of the designed simulation model is confirmed by presented computer simulation results.


KURHINEN, J. — JANATUINEN, J.
Delay Tolerant Routing in Sparse Vehicular Ad Hoc Networks [full paper]

Low density of network nodes in Vehicular Ad Hoc Networks (VANETs) outside the rush hours and in peripheral areas limits usability of traditional ad hoc networking, which requires end-to-end connectivity between communicating parties. In this article, we survey how usability of vehicular networks could be escalated with delay-tolerant networking, in which vehicles store and carry network data while waiting opportunities to forward it. With delay-tolerant networking applications are able to get eventual data delivery even in sparse networks. We address the routing problem in delay-tolerant vehicular networks and introduce a novel geographical routing scheme, which is based on movement predictions. As our simulations show, the presented protocol attains efficient results even in sparse networks.


KOLÁŘOVÁ, E.:
An Application of Stochastic Integral Equations to Electrical Networks [full paper]

In this paper we present an application of the Itˆo stochastic calculus to the problem of modelling inductor-resistor electrical circuits. The deterministic model of the circuit is replaced by a stochastic model by adding a noise term in the source. We also consider the case when both the source and the resistance are random. The analytic solutions of the resulting stochastic integral equations are found using the multidimensional Itˆo formula. We also examined statistical estimates of the stochastic solutions. The programming language C#, a part of the new MS .NET platform, is used for numerical simulations.


DRIF, M. — CARDOSO, A.
Instantaneous Non-Active Power Approach for Airgap Eccentricity Fault Diagnosis in Three-Phase Induction Motors [full paper]

This paper firstly presents a modelling and simulation study concerning the occurrence of airgap eccentricity in three-phase induction motors. For that purpose, the winding function approach is considered. Then, the instantaneous non-active power signature analysis is used as a new tool for the detection of mixed airgap eccentricity condition in operating three-phase squirrel cage induction motors. Simulation and experimental results are presented to illustrate the merits of the proposed approach.


GAMEC, J. — GAMCOVÁ, M.
The Fast Search Motion Estimation Algorithms and their Errors [full paper]

This paper presents the analysis of errors produced by block matching motion estimation methods with lower computational cost (fast search algorithms). We try to find an answer on the question what measure can be used to determine correctness of searched motion vectors and which motion vectors are founded as fault (corrupted by noise). We consider the vector fields obtained by using of full search algorithm (FSA) as lossless data. We take the vectors of movement obtained by using 2D logarithmic (2D log) search procedure as data corrupted by noise. The results of analysis can help optimize post processing of motion vectors in endeavoring to reduce computational cost or regularize vector fields.


NAAMA, B. — BOUZEBOUDJA, H. — RAMDANI, Y. — CHAKER, A.:
Hybrid Approach to the Economic Dispatch Problem Using a Genetic and a Quasi-Newton Algorithms [full paper]

In this paper, we present a hybrid optimization approach to solving the economic dispatch (ED) problem. The objective is to minimize the total fuel cost and keep the power flows within the security limits. The idea consists in combining principles from real coded genetic algorithms (RCGAs) [1] and a parallel quasi-Newton method (QN), in order to find a better compromise trade-off and a better precision while requiring a reasonable computing time. The approach that is presented utilizes both local and global optimization algorithms to find good design points more efficiently than either could. A parallel quasi-Newton method is used to explore the space of research and exploit all local information to progress towards a better point. The proposed approach improves the equality of the solution and speed of convergence of the algorithms. The hybrid methods developed is compared with a RCGAs and a classical methods of QN. The proposed approach has been tested on the IEEE 57 bus system [2].


ILLÉS, Z. — PŠENÁKOVÁ, I. — HEIZLERNÉ-BAKONYI, V.:
New Perspectives of M-Learning [full paper]

The traditional learning methods were completed with electronic possibilities due to the spread of internet. The global needs, for mobilities have an effect of this field too. Be Mobile! Everything everywhere! We meet the usage of mobile environments in the most different field of life. There are available now a lot of educational, learning possibilities (E-Learning). The needs of mobile technology, require that the methodology and the server framework of the E-Learning tool-kit has to be changed. It is often used M-Learning as an ELearning independent from location, time or space. A good method of changing the framework can be the storing small contents in XML structures this guarantees the quick and effective page generation and the structural relations.


KLIMEŠ, C.
Expert System Utilization for Modeling the Decision Making Processes upon Indetermination [full paper]

Computer aided modeling of the decision making processes requires the availability of a system, enabling to gather the knowledge of numerous experts. That is why the subject matter concerns first the simulation of the decision making processes, as well as the methods and procedures of knowledge acquisition from the above experts.


BENDJEBBAR, M. — ZERIKAT, M.:
Contribution to the Neuro-Fuzzy Control of Voltage Induction Machine Inverter Fed [full paper]

This article presents a modern strategy to improve the performance of electrical drives control. The approach used consists of combining both fuzzy and neural control algorithms to make better use of the knowledge resulting from both techniques. The numerical simulation tests carried have shown that the techniques robustness are very good and the obtained results validate the proposed neuro-fuzzy control diagram taking into account the induction motor model complexity due to high non linearity presence.


KOLLÁR, M.:
Evaluation of Real Call Set up Success Rate in GSM [full paper]

The Call Set up Success Rate is one of the most important Key performance Indicators (KPIs) used by all mobile operators. However there is no standard measurement possible for this parameter. Therefore the different operators can measure it differently. In this paper, a definition of a real Call Set up Success Rate, possibility of its implementation using the current technologies in GSM and difference between the real and implemented Call Set up Success rate is provided. The “real” in this case means that Call Set up Success Rate is calculated as ratio of the assigned TCHs to the channel requests. The error in measurement of real Call Set up Success Rate with activated Direct TCH Assignment feature is evaluated as well. The proposed error modeling can be used in order to guarantee a quality in measurement of Call Set up Success Rate.


HAMOUDA, M. — FLAZI, S.:
Study of the Pollution Resistance in Front of the Flashover Discharge on a Disk Model [full paper]

In this paper the pollution resistance before the foot of the discharge, and the geometrical form of the leakage current lines, during the evolution of the discharge until flashover, is very important for the modelling of this phenomenon on a real insulator, and for the determination of its critical conditions. To study this problems, we have achieves a new model of laboratory. This model looks like a real insulator of electric lines in his shape and also in his pollution. The suggested model is valid to act well as go-between the real insulator and simple laboratory models which have carefully studied. In this paper we present our model with its characteristics and the experimental results of its use for measuring the critical voltage and the pollution resistances between the ground electrode and a static discharge for many discharge positions.


CHOCHLÍK, M.:
Storing Dimensions and Units of Physical Quantities in a Relational Database
[full paper]

Many relational databases store records with columns containing various physical properties of the stored items. However when using these data, the dimension and unit checking is often left to the application logic. In physical calculations the individual terms represent various quantities both those having dimensions and dimensionless. Furthermore the values can be expressed in various units. The dimensions and units are important as a type system that is ensuring correctness and provide information about the meaning of the terms and results of the calculations. This paper presents the design of a working implementation of a subsystem representing physical quantities and units in the PostgreSQL database system.

MIŠÁK, M.:
Mathematical Model of Electric Arc Respecting Mayr Theory in EMTP-ATP [full paper]

The mathematical interpretation of an electric arc is practically very difficult by virtue of its extremely accidental character. But on the other side, the mathematical formulation course of the electric arc is possible with transfer to the area of the mathematical modeling for specific conditions. Limits of influences of the electric arc are possible to determine with using results from mathematical simulations. The mathematical model of the electric arc defined at simulation program EMTP-ATP and respecting Mayr theory is introduced within this paper. Results from simulations defining the influence of the electric arc on the medium voltage system are introduced within paper too.


 

Publisher

    Faculty of Electrical Engineering and Informatics, Technical University of Košice, Slovak Republic

    Reg. No.: EV 2921/09,
    thematic group B1,
    ISSN 1335-8243
    The editorial board assumes no responsibility for damages suffered due to use of acts, methods, products, instructions for use or other ideas published by the article authors whatsoever.
EAN 9771335824005