Communications - Scientific Letters of the University of Zilina, 2013 (vol. 15), issue 2A
Articles
Simulation and Examination of a Signal Masking Chaotic Communication System, Based on the Duffing Oscillator
Galina Cherneva, Elena Dimkina
Communications - Scientific Letters of the University of Zilina 2013, 15(11):6-10 | DOI: 10.26552/com.C.2013.2A.6-10 
The study in this paper is focused on the applications of the chaotic Duffing oscillator to signal masking communication scheme. Using the concept of synchronized chaotic systems the signal masking approach is demonstrated with the Duffing oscillator implemented in both the transmitter and receiver. The chaotic masking signal is added at the transmitter to the information signal, and at the receiver, the masking is regenerated and subtracted from the received signal. Chaotic behavior and chaotic masking scheme are designed and simulated using Simulink/Matlab program. All the results are used to illustrate the effectiveness and the applicability of...
Decision Trees as a Tool for Real-Time Travel Time Estimation on Highways
Jakub Wosyka, Pavel Pribyl
Communications - Scientific Letters of the University of Zilina 2013, 15(11):11-16 | DOI: 10.26552/com.C.2013.2A.11-16
This paper presents a time travel estimation model based on a decision tree. Input parameter for travel time prediction is occupancy of detectors. The proposed model was tested on the most widely used arterial in Prague and also in the Czech Republic. This road section has many unmeasured inputs and outputs and with regards to only two detectors within a section it is difficult to estimate the travel time. A temporary installation of ALPR system is used for training the decision tree model which consequently provides reliable travel time estimation.
Self-Calibration of the Resolver Sensor in Servo Drive Application
Jan Faber, Marek Stulrajter, Jan Vittek
Communications - Scientific Letters of the University of Zilina 2013, 15(11):17-22 | DOI: 10.26552/com.C.2013.2A.17-22
Resolver sensor is utilized as absolute position transducer in many industrial motion-control applications where robustness and ability to operate in harsh environment is required. In real system, the quality of position and speed measurement is badly affected by the resolver errors. In this paper, the software-based error-compensation technique is integrated into the control structure of the drive. Compensation scheme adapts online to errors in the resolver signals in order to improve accuracy of the measured position and speed. Performance of the compensation scheme and the effect on the drive operation is verified through experimental testing.
Design, Construction and Experimental Verification of Magnetorheological Brake
Petr Polcar
Communications - Scientific Letters of the University of Zilina 2013, 15(11):23-27 | DOI: 10.26552/com.C.2013.2A.23-27
This article deals with the principle, design and verification of the magnetorheological brake. Physical principles, possible designs and advantages of magnetorheological brakes are presented. A design is chosen, simulated and device is built. Simulations are compared with results obtained from measurements on the device, suitable magnetorheological fluid is chosen and torque characteristics of the brake are experimentally verified.
Yeast Growth Influenced by Parallel Combination of Time-Varying and Static LF EMF
Roman Radil, Ladislav Janousek
Communications - Scientific Letters of the University of Zilina 2013, 15(11):28-32 | DOI: 10.26552/com.C.2013.2A.28-32
Presented article deals with the mechanisms of low frequency electromagnetic field impact on biological structures. Special attention is paid to the theories describing the influence of applied electromagnetic field on microtubule structures and ions bound on the cell membrane surface. These theories are confronted with the experiments presented herein. For better reliability of the experiments, new exposure coil system has been designed and created. Using this exposure system, results are conducted on the eukaryotic cells represented by saccharomyces cerevisiae. Observed effects show a good correlation mainly with ion parametric resonance model predictions...
Analysis of Dielectric Properties of Lithium Phosphate Glasses
Peter Hockicko, Peter Bury, Francisco Munoz
Communications - Scientific Letters of the University of Zilina 2013, 15(11):33-39 | DOI: 10.26552/com.C.2013.2A.33-39
Dielectric relaxation spectra of lithium phosphate glasses are used to analyze the change of real and imaginary part of complex permittivity including loss tangent of ion conductive glasses. The experimental results getting from a.c. and d.c. electric measurements on Li phosphate glasses are analyzed, discussed and compared. Frequency dependence of the permittivity spectra is found to be consistent with the analysis of d.c. electrical conductivity. The universal a.c. conductivity law (universal dynamic response) for glass ionic conductor was confirmed. Arrhenius graphs constructed from a.c. and d.c. electrical measurements including loss tangent are...
Separation of Plastic Particles in Electrostatic Field Produced by Electrodes of Optimized Shape
Frantisek Mach, Pavel Kus, Pavel Karban, Ivo Dolezel
Communications - Scientific Letters of the University of Zilina 2013, 15(11):40-45 | DOI: 10.26552/com.C.2013.2A.40-45
Shape optimization of electrodes for the device for electrostatic separation of triboelectrically charged plastic particles is carried out. The objective function maximizes the efficiency of separation consisting in the highest possible number of particles falling down to the prescribed bins. Electric field in the system is solved numerically, using the fully adaptive higher-order finite element method. The movement of particles in the device influenced by the Coulomb force is determined by means of an adaptive Runge-Kutta-Fehlberg method with a time varying time step. The shape optimization is carried out using a technique based on genetic algorithms....
Losses, Efficiency and Thermal Behavior of the Synchronous Motors with Different PM Materials
Peter Sekerak, Valeria Hrabovcova, Matus Onufer, Pavol Rafajdus, Lukas Kalamen
Communications - Scientific Letters of the University of Zilina 2013, 15(11):46-54 | DOI: 10.26552/com.C.2013.2A.46-54
The paper deals with losses, efficiency and thermal behavior of the synchronous machines with different permanent magnet (PM) materials. Three PMSM are presented in this paper: First, the PMSM with NdFeB PM, which is really constructed. Second, the NdFeB was replaced by ferrites PM. Third, the new design of synchronous motor with ferrites is presented. The volume of PM and the whole size are increased to keep the same power output. Equivalent circuit parameters, EMF, V-curves, losses, efficiency and thermal behavior of all three machines are investigated and compared.
Novel Approach to Color Texture Retrieval Based on GLCM
Miroslav Benco, Robert Hudec, Martina Zachariasova, Patrik Kamencay, Slavomir Matuska
Communications - Scientific Letters of the University of Zilina 2013, 15(11):55-59 | DOI: 10.26552/com.C.2013.2A.55-59
The color and texture are very important features in image analysis. In this paper, the combination of these features is presented. Several approaches for color texture features extraction are researched. The improvement of the one-dimensional version of GLCM (Gray Level Co-occurrence Matrix) for color textures was designed. We named this method as Color Level Co-occurrence Matrix (1D-CLCM). The experiments on database of 2600 color images are provided. Finally, the evaluation and comparison of image retrieval results for separate methods are presented.
Analysis of Switched Reluctance Motor Behavior under Electrical Fault Conditions
Peter Dubravka, Pavol Rafajdus, Pavol Makys, Valeria Hrabovcova, Lorand Szabo
Communications - Scientific Letters of the University of Zilina 2013, 15(11):60-66 | DOI: 10.26552/com.C.2013.2A.60-66
This paper deals with analysis of Switched Reluctance Motor (SRM) behavior under fault conditions. The static parameters of the healthy SRM and SRM with defined faults of phases are investigated by Finite Element Method (FEM). These static parameters are used in dynamic simulation of the SRM. Transients are simulated for the healthy motor and for the motor under fault conditions. Results of the simulations are compared with experimental measurements.
Spectral Transmission Characteristics of Andvanced Amplitude Modulation Formats
Daniel Benedikovic, Jan Litvik, Michal Kuba, Milan Dado
Communications - Scientific Letters of the University of Zilina 2013, 15(11):67-70 | DOI: 10.26552/com.C.2013.2A.67-70
In this paper we focus our attention on numerical investigation of high-order amplitude modulation format in single-channel transmission systems utilizing different kinds of optical fibers. The aim is to show the spectral behavior of advanced amplitude modulated signals in view of fundamental parameters of fiber-optic system. The investigation is realized by solving the nonlinear Schrodinger equation (NLSE) through the pseudospectral split-step Fourier method (SSFM). The obtained results show that the advanced amplitude modulation formats are sensitive to nonlinear phenomenon and they are more desirable for using at short-haul networks.
Restoration of Deterministic and Interference Distorted Signals and Images with Use of the Generalized Spectra Based on Orthogonal Polynomials and Functions
Oleg V. Chernoyarov, Martin Breznan, Alexander V. Terekhov
Communications - Scientific Letters of the University of Zilina 2013, 15(11):71-77 | DOI: 10.26552/com.C.2013.2A.71-77
Restoration algorithms of signals and images on the basis of their generalized spectra in bases of orthogonal polynomials and functions at absence and presence of random distortions have been examined. It is shown that in absence of hindrances the number of coefficients of the generalized spectrum of a restored signal (image) is determined by the desired approximation error at use of one or another metrics of functional space. If hindrances take place then there is an optimum number of coefficients of the generalized spectrum for signal (image) restoration. Working data of the proposed algorithms for various types of useful signals have been illustrated.
Investigation of the Thermal Sensitive Spectral Response of Chalcogenide Fiber Bragg Grating
Eliska Jurisova, Libor Ladanyi, Jarmila Mullerova
Communications - Scientific Letters of the University of Zilina 2013, 15(11):78-83 | DOI: 10.26552/com.C.2013.2A.78-83
This contribution presents numerical studies of the nonlinear fiber Bragg grating (FBG). The proposed model corresponds well to chalcogenide FBG as a considerable tool for optical switching. The spectral response of this device is discussed theoretically. Simulations based on the nonlinear coupled mode theory are used for investigating the relationships between the spectral transmission of nonlinear chalcogenide FBG and the grating parameters. The influence of the temperature dependence of FBG is numerically investigated. Numerical results show that the ambient temperature has an influence on the spectral response of FBG. The results are indications...
Photonic Crystal Fiber Modal Interferometer for Refractive Index Sensing
Daniel Kacik, Peter Tatar
Communications - Scientific Letters of the University of Zilina 2013, 15(11):84-88 | DOI: 10.26552/com.C.2013.2A.84-88
We present a modification of core-cladding intermodal interferometer for refractive index sensing. Its structure consists of double cladding photonic crystal fiber (PCF) as a sensing element. First cladding allows fundamental mode propagation only. Second cladding consists of ring of holes with the average refractive index higher than the basic material of the fiber and it is situated close to interface fiber-external environments. So the cladding mode is confined in the ring of holes and its evanescent field extends to external environment. Advantages of this arrangement against core - cladding interferometers are higher sensitivity and, by suitable...
Semantic Web Related to ITS Systems
Pavel Pribyl, Vit Fabera, Vladimir Faltus, Lukas Tyfa
Communications - Scientific Letters of the University of Zilina 2013, 15(11):89-95 | DOI: 10.26552/com.C.2013.2A.89-95
This paper describes a way to better navigate in an ever increasing number of standards in the field of ITS. Short overview about fundamental ITS models is presented, the principles of related knowledge system are described. Ontology approach is used, especially as domain-oriented ITS ontology, where a new hybrid method is explained.
Calculation and Measurement of RFID Tag Critical Frequency
Peter Vestenicky, Martin Vestenicky, Juraj Palecek
Communications - Scientific Letters of the University of Zilina 2013, 15(11):96-101 | DOI: 10.26552/com.C.2013.2A.96-101
This paper deals with undesirable phenomenon in inductively coupled RFID system, i. e. by fading out the amplitude modulation of carrier signal in RFID reader. It is caused by inaccurate tuning of RFID transponder resonant circuit. The phenomenon is described by mathematical model of the inductively coupled RFID system. The numerical and graphical results of mathematical modelling is then compared by measurement of resonant frequency of real (tuneable) RFID circuit on which the amplitude modulation fades out.
Influence of Selected Parameters on Eddy Currents Attenuation in Non-Destructive Inspection
Ladislav Janousek
Communications - Scientific Letters of the University of Zilina 2013, 15(11):102-106 | DOI: 10.26552/com.C.2013.2A.102-106
Eddy currents attenuation in conductive materials under non-destructive inspection is analyzed in the paper. Influence of selected parameters of the inspection on the attenuation is studied by numerical means. A circular driving coil is employed to induce eddy currents in conductive plates under harmonic excitation. Outer diameter of the coil is varied together with the clearance between the coil and a plate surface for two plates with different thickness. Attenuation of the eddy current density in plates is studied and the results are analyzed in absolute values and the normalized ones as well. It is demonstrated that the investigated parameters of...
Performance and Fuel Consumption Optimizations of Shunting Hybrid Locomotives
Matej Pacha, Jiri Stepanek
Communications - Scientific Letters of the University of Zilina 2013, 15(11):107-112 | DOI: 10.26552/com.C.2013.2A.107-112
In recent years hybrid electric drive has become very popular in public transportation and automobiles. This article deals with hybrid drive technology and its impact on performance and energy consumption optimization of shunting locomotives in comparison with conventional diesel-electric locomotives. Based on classic longitudinal train dynamics theory of train movement and with support of simulation results, a comparison of electrochemical accumulators and super-capacitors impact is also introduced.
Study of the Energy Parameters and Possibilities for Modernization of Electric Vehicles for AC Power
Georgy Pavlov
Communications - Scientific Letters of the University of Zilina 2013, 15(11):113-117 | DOI: 10.26552/com.C.2013.2A.113-117
The main problem with thyristor locomotives operated in the country is the low value of the power factor. The paper presents results of a survey of the quality of power consumption in this type of locomotives. Based on the experimental data analyzed, we have determined the main parameters characterizing the traction power consumption. Indicated are some general guidelines for optimization.
Inversed Matrixes in Electric Circuits Parameters Estimation by Oriented Graphs
Sona Pavlikova, Dusan Maga, Boris Simak
Communications - Scientific Letters of the University of Zilina 2013, 15(11):118-123 | DOI: 10.26552/com.C.2013.2A.118-123
The base of electric circuit analysis is often set up on numerical methods. When taking a look into the principle of any numerical method, a matrix calculus always rises out. The larger the problem is, the larger is the size of the matrix, representing the logical structure of the solved problem [1]. The problem (especially from the mathematical point of view) is in acquiring the inverse matrix, which can be solved with some of a large scale of available numerical (or analytical; based on the size of matrixes) methods. This paper shows another possible approach to obtaining the inverse matrix. The graph theory has already been successfully used to...
Building of Broadcast News Database for Evaluation of the Automated Subtitling Service
Matus Pleva, Jozef Juhar
Communications - Scientific Letters of the University of Zilina 2013, 15(11):124-128 | DOI: 10.26552/com.C.2013.2A.124-128
This paper describes the process of recording, annotation, correction and evaluation of the new Broadcast News (BN) speech database named KEMT-BN2, as an extension for our older KEMT-BN1 and COST-278 databases used for automatic Slovak continuous speech recognition development. The database utilisation and statistics are presented. This database was prepared for evaluation of the automated BN transcription system, developed in our laboratory, which is mainly used for subtitle generation for recorded BN shows. The speech database is the key part of the acoustic models training for specific domains and also for speaker and anchor adapted models creation.
More Accurate Modelling of Digital Subscriber Lines with Inhomogeneity
Jiri Vodrazka, Petr Jares, Boris Simak
Communications - Scientific Letters of the University of Zilina 2013, 15(11):129-133 | DOI: 10.26552/com.C.2013.2A.129-133
The digital subscriber lines are still base of access network to provide Internet connectivity to the public. The transmission capacity is continually increased and performance of digital subscriber lines must be estimated for network provider use. This paper describes two ways for correction of digital subscriber line modelling. The resulting bitrates are calculated with respect to the length of the line and the number of disturbance sources. The article brings new ideas for simulations and calculations of transmission function for line with inhomogeneity and calculations new value of code gain.
Functionality Validation of the New QOS and Security Integration Model for Manet
Jan Papaj, Lubomir Dobos, Anton Cizmar
Communications - Scientific Letters of the University of Zilina 2013, 15(11):134-138 | DOI: 10.26552/com.C.2013.2A.134-138
In this article, the simulation testbed of the new designed model for cooperation between QoS and security is introduced. The field of research about QoS and security provide dynamically developed and important areas of the research and up to now no protocol or mechanisms have been designed to this process. The cooperation is based on using a Cross Layer Design model (CLD) and modified Security Service Vector (SSV). A main idea of testbed is the indication how could security and QoS be integrated as a parameter to the MANET via this model. We also show how this model can affect the functionalities of the whole MANET.
Proposal of Load Aware Routing for OSPF Routing Protocol
Tomas Macha, Radko Krkos, Vit Novotny
Communications - Scientific Letters of the University of Zilina 2013, 15(11):139-144 | DOI: 10.26552/com.C.2013.2A.139-144
This paper deals with route cost assignment using one of the most commonly used routing protocols - Open Shortest Path First (OSPF). The limitation of this protocol is that the algorithm does not take actual link load into consideration. This paper proposes using an alternate costing strategy to avoid this problem. The alternate strategy uses an integer value representing the load of a link as the additive component of metric. Since the link load is a dynamic variable, Exponential Weighted Moving Average is used to counter quick changes. This paper proposes a novel approach to calculate OSPF metrics, aimed to better distribute the load in network.
Novel Watermarking Methods Based on Frequency Domain and Singular Value Decomposition
Petr Cika, Martin Zukal
Communications - Scientific Letters of the University of Zilina 2013, 15(11):145-149 | DOI: 10.26552/com.C.2013.2A.145-149
Nowadays, the copyright laws protecting the digital content are getting quite common. One of the important things is to protect the original or compressed images against illegal use. Frequency domain watermarking methods are used in most cases in today's image- and videowatermarking algorithms. Especially Discrete Wavelet Transform (DWT) and Discrete Cosine Transform (DCT) are used in watermarking algorithms. This paper deals with development of two novel digital image watermarking methods that use DWT with Singular Value Decomposition (SVD) and DCT with SVD. The paper includes step by step process of watermark embedding and extraction and testing...
Exploratory Analysis of Virtualization Tools in Delay-Sensitive Environment
Miroslav Voznak, Jiri Slachta, Filip Rezac, Jan Rozhon
Communications - Scientific Letters of the University of Zilina 2013, 15(11):150-154 | DOI: 10.26552/com.C.2013.2A.150-154
This article deals with an exploratory analysis of virtualized real-time applications. We compare selected virtualizations tools and present the achieved results in boxplots based on the performed exploratory analysis. The paper analyzes the impact of memory size and the number of processor cores on the delay itself and its variance in selected set of virtualization tools.
The Influence of Binary Modulations in OTDM
Petr Munster, Radim Sifta, Vladimir Tejkal, Miloslav Filka
Communications - Scientific Letters of the University of Zilina 2013, 15(11):155-159 | DOI: 10.26552/com.C.2013.2A.155-159
In this paper we propose a simulation test using different binary modulation formats in optical network based on the Optical Time Division Multiplexing (OTDM). OTDM in optical networks is used for high speed data generation in point-to-point networks. Dispersion and nonlinearities in optical fibers can cause transmission disturbances, which can influence the throughput of the transmission system and maximal achievable distance. Basic modulation formats RZ and NRZ with new CRZ and CSRZ formats were tested in OTDM simulation model.
Simulation of Line Array Sound Source
David Kurc, Jiri Schimmel
Communications - Scientific Letters of the University of Zilina 2013, 15(11):160-166 | DOI: 10.26552/com.C.2013.2A.160-166
This paper is focused on the simulation of line array source that consists of eight separate loudspeaker enclosures of the same type having some directional characteristics influenced by the position within the line array. The influence on these characteristics caused by the different positions of enclosures in the array was tested. The characteristics of the line array source were measured in the anechoic chamber. The comparison between the results of the simulation of ideal and real sources is shown.
Performance Analysis of Turbo Codes
Jakub Sedy, Pavel Silhavy, Ondrej Krajsa, Ondrej Hrouza
Communications - Scientific Letters of the University of Zilina 2013, 15(11):167-173 | DOI: 10.26552/com.C.2013.2A.167-173
The article focuses on the performance analyses of Turbo Codes. These codes belong to the group of error correction codes. By their use, it is possible to achieve high system performance. The performance analysis is based on simulations for different code parameters that affect the code gain, bit error rate and computational complexity. Furthermore, it presents the basic structure of the encoder and decoder and the principle of encoding and decoding, which uses the Viterbi algorithm with soft input and soft output.
Image Extrapolation Using Sparse Methods
Jan Spirik, Jan Zatyik
Communications - Scientific Letters of the University of Zilina 2013, 15(11):174-179 | DOI: 10.26552/com.C.2013.2A.174-179
Image extrapolation is the specific application in image processing. You have to extrapolate the image for example when you want to process the given image piecewise. When the border patches are incompleted you must extrapolate them to the given size. Nowadays,some basic extrapolations, e.g. linear, polynomial etc. are used. The advanced methods are presented in this paper. We are using the algorithms that are based on finding the sparse solutions in underdetermined systems of linear equations. Three algorithms are presented for image extrapolation. First one is the K-SVD algorithm. K-SVD is the algorithm that trains a dictionary which allows the optimal...
Bruteforce Attacks Blocking Solution on Embedded SIP Communication Server
Filip Rezac, Jakub Safarik, Miroslav Voznak, Jan Rozhon, Karel Tomala, Jiri Vychodil
Communications - Scientific Letters of the University of Zilina 2013, 15(11):180-184 | DOI: 10.26552/com.C.2013.2A.180-184
This article deals with embedded SIP communication server with an easy integration into the computer network based on open source solutions and its effective defense against the most frequent attack in the present - Denial of Service. The article contains brief introduction into the Bright Embedded Solution for IP Telephony - BESIP and describes the most common types of DoS attacks, which are applied on SIP elements of the VoIP infrastructure including the results of defensive mechanism that has been designed.
Image Segmentation and Feature Extraction Using Sift-Sad Algorithm for Disparity Map Generation
Patrik Kamencay, Martina Zachariasova, Robert Hudec, Miroslav Benco, Jan Hlubik, Slavomir Matuska
Communications - Scientific Letters of the University of Zilina 2013, 15(11):185-190 | DOI: 10.26552/com.C.2013.2A.185-190
In this paper, a stereo matching algorithm based on image segments and disparity measurement using stereo images is presented. We propose the hybrid segmentation algorithm that is based on a combination of the Belief Propagation and Mean Shift algorithms with aim to refine the final disparity map by using a stereo pair of images. Firstly, a color based segmentation method is applied for segmenting the left image of the input stereo pair (reference image) into regions. The aim of the segmentation is to simplify representation of the image into the form that is easier to analyze and is able to locate objects in images. Secondly, results of the segmentation...
IP Telephony Server Emulation for Monitoring and Analysis of Malicious Activity in VOIP Network
Jakub Safarik, Miroslav Voznak, Filip Rezac, Lukas Macura
Communications - Scientific Letters of the University of Zilina 2013, 15(11):191-196 | DOI: 10.26552/com.C.2013.2A.191-196
The paper aims at gathering information about attacks from real internet infrastructure and their analysis. For this purpose, we prepared a set of honeypots monitoring various aspects of VoIP infrastructure including SIP endpoint and SSH terminal emulation. SIP endpoints are registered with real SIP registrar and the incoming calls are routed to a honeypot according the rules in dialplan. The honeypot gathers valuable data about hacker's activity with no threat to production systems. Analysis of the honeypot data is crucial for further improvement of existing security mechanisms in VoIP networks. The paper describes the honeypot's behaviour and brings...