AEEE. 2011, vol. 9

Permanent URI for this collectionhttp://hdl.handle.net/10084/84480

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Now showing 1 - 20 out of 33 results

Comparison of current frame-based phoneme classifiers
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Pfeifer, Václav; Balík, Miroslav
This paper compares today’s most common frame-based classifiers. These classifiers can be divided into the two main groups – generic classifiers which creates the most probable model based on the training data (for example GMM) and discriminative classifiers which focues on creating decision hyperplane. A lot of research has been done with the GMM classifiers and therefore this paper will be mainly focused on the frame-based classifiers. Two discriminative classifiers will be presented. These classifiers implements a hieararchical tree root structure over the input phoneme group which shown to be an effective. Based on these classifiers, two efficient training algorithms will be presented. We demonstrate advantages of our training algorithms by evaluating all classifiers over the TIMIT speech corpus.
E-model MOS estimate improvement through jitter buffer packet loss modelling
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Kováč, Adrián; Halas, Michal; Orgon, Miloš; Vozňák, Miroslav
Proposed article analyses dependence of MOS as a voice call quality (QoS) measure estimated through ITU-T E-model under real network conditions with jitter. In this paper, a method of jitter effect is proposed. Jitter as voice packet time uncertainty appears as increased packet loss caused by jitter memory buffer under- or overflow. Jitter buffer behaviour at receiver’s side is modelled as Pareto/D/1/K system with Pareto-distributed packet interarrival times and its performance is experimentally evaluated by using statistic tools. Jitter buffer stochastic model is then incorporated into E-model in an additive manner accounting for network jitter effects via excess packet loss complementing measured network packet loss. Proposed modification of E-model input parameter adds two degrees of freedom in modelling: network jitter and jitter buffer size.
Security analysis system to detect threats on a SIP VoIP infrasctructure elements
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Řezáč, Filip; Vozňák, Miroslav; Tomala, Karel; Rozhon, Jan; Vychodil, Jiří
SIP PBX is definitely the alpha and omega of any IP telephony infrastructure and frequently also provides other services than those related to VoIP traffic. These exchanges are, however, very often the target of attacks by external actors. The article describes a system that was developed on VSB-TU Ostrava as a testing tool to verify if the target VoIP PBX is adequately secured and protected against any real threats. The system tests the SIP element for several usually occurring attacks and it compiles evaluation of its overall security on the basis of successfully or unsuccessfully penetrations. The article describes the applications and algorithms that are used by system and the conclusion consists recommendations and guidelines to ensure effective protection against VoIP PBX threats. The system is designed as an open-source web application, thus allowing independent access and is fully extensible to other test modules.
Innovation of methods for measurement and modelling of twisted pair parameters
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Čepa, Lukáš; Kozák, Miloš; Vodrážka, Jiří
The goal of this paper is to optimize a measurement methodology for the most accurate broadband modelling of characteristic impedance and other parameters for twisted pairs. Measured values and theirs comparison is presented in this article. Automated measurement facility was implemented at the Department of telecommunication of Faculty of electrical engineering of Czech technical university in Prague. Measurement facility contains RF switches allowing measurements up to 300 MHz or 1GHz. Measured twisted pair’s parameters can be obtained by measurement but for purposes of fundamental characteristics modelling is useful to define functions that model the properties of the twisted pair. Its primary and secondary parameters depend mostly on the frequency. For twisted pair deployment, we are interested in a frequency band range from 1 MHz to 100 MHz.
Study of Vivaldi algorithm in energy constraint networks
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Morávek, Patrik; Komosný, Dan; Vajsar, Pavel; Švéda, Jaroslav; Handl, Tomáš
The presented paper discusses a viability of Vivaldi localization algorithm and synthetic coordinate system in general to be used for localization purposes in energy constraint networks. Synthetic coordinate systems achieve good results in IP based networks and thus, it could be a perspective way of node localization in other types of networks. However, transfer of Vivaldi algorithm into a different kind of network is a difficult task because the different basic characteristic of the network and network nodes. In this paper we focus on the different aspects of IP based networks and networks of wireless sensors which suffer from strict energy limitation. During our work we proposed a modified version of two dimensional Vivaldi localization algorithm with height system and developed a simulator tool for initial investigation of its function in ad-hoc energy constraint networks.
Tree-oriented data acquisition architecture
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Novotný, Vít
Hierarchical system of network nodes is suitable solution how to collect and how to pre-process data from large amount of end-nodes. By contrast to flat (one layer) architecture there are special intermediary nodes used and they are called summarization nodes. These special nodes have to be suitably placed in the network to enable efficient data collection and their number in the hierarchy is one of the key parameters of the architecture. The article deals with the tree architecture design, with its optimisation and with the problem of limited number of summarization nodes.
The efficiency of constraint based routing in MPLS networks
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Mecvecký, Martin
The paper presents the simulation results and evaluates the efficiency of constraint base routing algorithms used in MPLS network from the point of their usability in Next Generation Networks. The efficiency of constraint based routing is evaluated according following criteria: optimal path selection, routing priority of traffic flows selected for constraint routing and bandwidth allocation by MAM or RDM bandwidth constraints models.
Damaged watermarks detection in frequency domain as a primary method for video concealment
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Hudec, Róbert; Bojmir, Martin; Benco, Miroslav
This paper deals with video transmission over lossy communication networks. The main idea is to develop video concealment method for information losses and errors correction. At the beginning, three main groups of video concealment methods, divided by encoder/decoder collaboration, are briefly described. The modified algorithm based on the detection and filtration of damaged watermark blocks encapsulated to the transmitted video was developed. Finally, the efficiency of developed algorithm is presented in experimental part of this paper.
Cross-sectional measuring of optical beam
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) David, Tomáš; Látal, Jan; Hanáček, František; Koudelka, Petr; Vitásek, Jan; Šiška, Petr; Skapa, Jan; Vašinek, Vladimír
This article deals with problematic of measuring of optical beam in free space optics (FSO). The professional FSO link was created between two buildings standing 1,5 kilometers apart from each other. Signal passing through the atmospheric media between optical heads is affected. This happens due to effects in atmospheric media. This article describes creating of the device for measuring the intensity of optical beam in 2D space and its subsequent rendering into 3D graph.
A concept of a hybrid WDM/TDM topology using the Fabry-Perot laser in the Optiwave simulation environment
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Pobořil, Radek; Látal, Jan; Hanáček, František; Koudelka, Petr; Vitásek, Jan; Šiška, Petr; Skapa, Jan; Vašinek, Vladimír
The aim of this article is to point out the possibility of solving problems related to a concept of a flexible hybrid optical access network. The entire topology design was realized using the OPTIWAVE development environment in which particular test measurements were carried out as well. Therefore, in the following chapters, we will subsequently focus on individual parts of the proposed topology and will give reasons for their functions whilst the last part of the article consists of values measured in the topology and their overall evaluation.
Application of results of experimental identification in control of laboratory helicopter model
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Dolinský, Kamil; Jadlovská, Anna
This article deals with experimental identification and control of laboratory helicopter model CE 150 manufactured by company Humusoft. Structure of the identified system was approximated by linear black-box models. Discrete Input/Output Auto-Regressive Moving Average model with eXternal input (ARMAX) and its state space equivalent were used. Parameters of the models were estimated by regression techniques using System Identification Toolbox for Matlab. Acquired models were validated using simulations, residual analysis and real-time control. Input/output data necessary for identification were obtained by measurements from laboratory model and were processed using Real-Time Toolbox for Matlab. Based on acquired mathematical models input/output and state space controllers were designed (input/output pole placement with integration, state space pole placement with integration and observer). Designed controllers were implemented in Matlab environment using the Real Time Toolbox and their performance was verified by real-time control of the helicopter model.
Novel power flow problem solutions method’s based on genetic algorithm optimization for banks capacitor compensation using an fuzzy logic rule bases for critical nodal detections
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Abdelfatah, Nasri; Brahim, Gasbaoui
The Reactive power flow’s is one of the most electrical distribution systems problem wich have great of interset of the electrical network researchers, it’s cause’s active power transmission reduction, power losses decreasing, and the drop voltage’s increase. In this research we described the efficiency of the FLC-GAO approach to solve the optimal power flow (OPF) combinatorial problem. The proposed approach employ tow algorithms, Fuzzy logic controller (FLC) algorithm for critical nodal detection and gentic algorithm optimization (GAO) algorithm for optimal seizing capacitor.GAO method is more efficient in combinatory problem solutions. The proposed approach has been examined and tested on the standard IEEE 57-bus the resulats show the power loss minimization denhancement, voltage profile, and stability improvement. The proposed approach results have been compared to those that reported in the literature recently. The results are promising and show the effectiveness and robustness of the proposed approach.
Temperature characterization of passive optical components for WDM-PON FTTx
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Chovan, Jozef; Uherek, František; Kurinec, Radoslav; Satka, Alexander; Pavlov, Jozef; Seyringer, Dana
In this paper we report on the experimental test set-up for the temperature characterization of optical multiplexers/demultiplexers in the C - telecommunication band. Particularly the temperature change of transmission parameters like polarization dependent loss and insertion loss are investigated. The measurements were performed in the temperature range and under ambient air-conditions equal to the installation of passive optical elements in the external outdoor non–climatic environment.
Efficient propulsion structure with an axial flux rotary converter for hev drive unit
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Havel, Aleš; Vaculík, Petr; Slivka, David
This paper describes an efficient axial flux arrangement of the four quadrant rotary converter for hybrid electric vehicles. The design of the axial flux wound stator and both axial flux squirrel cage rotors is based on the arrangement of radial air gap induction motor and permanent magnet synchronous motor. The method of constant magnetic circuit volume is utilized for dimensions conversion, which results into basic dimensions of stator and rotor discs in axial flux conception. This allows the creation of real 3D models in the CAD application. Finally, the finite element simulations of electromagnetic induction in the axial flux stator pack are presented in the concluding part of this paper.
Modelling of attenuation and crosstalk of cascaded transmission lines
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Lafata, Pavel
This paper deals with the measurements and modelling of attenuation and near-end (NEXT) and far-end (FEXT) crosstalk for cascaded metallic transmission lines. The transmission parameters of homogenous metallic line can be easily described by telegraph equations or cascade matrix; there are also several models for NEXT and FEXT frequency dependence. But these models and equations could not be applied in the situation of two or more different cascaded transmission lines, because these cascaded lines do not meet the essential condition of overall homogenous transmission line. However in such case, it is still possible to estimate the overall transmission characteristics of the whole combination thanks to the characteristics of each separate element. This paper brings the description of complex measurements performed for the combination of three different metallic cables and based on these measurements, several conclusions about the possibilities of modelling the attenuation and NEXT and FEXT crosstalk for cascaded transmission lines are presented.
Methods of calculation of digital signals spectra
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Cepciansky, Gustav; Schwartz, Ladislav
Modern telecommunication networks work on the transmission method of common data streams in which data bursts consisting of packets that further consist of particular bits are multiplexed from various traffic sources. The larger amount of data is transmitted through a transmission medium (optical fibre), the more frequently bursts occur, and the lower amount of data, the more rarely they follow. If it is required to monitor how large amount of data is being transmitted in a network branch in order to find out, to which measure this branch is occupied, it is not necessary to take each information unit (each packet or even each particular bit). It will do if information whether a data burst occurs in the transmission or does it not occur is taken in certain time intervals – with a certain sampling frequency. The paper deals with these sampling intervals.
A five level NPC inverter controlled by using SHEPWM strategy
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Cherchali, Noureddine Ould; Tlemcani, Abde Abdelhalim; Barazane, Linda; Boucherit, Mohamed Seghir
The object of this paper is to analyse the behavior and the performances of a three-phase induction machine supplied with a five level neutral-point-clamped (NPC) inverter controlled by Selective Harmonic Eliminated Pulse-Width Modulation Technique (SHEPWM). First, the modeling of the inverter and the machine is presented. Thereafter, a theoretical study of the harmonics elimination strategy is detailed; where the genetic algorithm (GA) for elimination purposes is used. After that, this strategy is validated by simulation. Finally, a behavior of the induction machine controlled with this inverter is presented.
Safety evalution of cryptography modules within safety related control systems for railway applications
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Franekova, Maria; Vyrostko, Marek
The paper deals with the problem of safety evaluation of cryptographic modules used within safety-related control system for applications with increasing safety integrity level. The requirements to cryptographic techniques in safety-related communication for railway application are describe. The mainly part is oriented to description of mathematical apparatus for an error probability of cryptography code with a safety code, used in an additional safety communication layer. The practical results are related with the quantitative evaluation of an average error probability of code word for Euroradio protocol recommended for communication in European Train Control System.
Data communication between programmable logic controllers in the industrial distribution applications
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Bystricanova, Anna; Rybovic, Daniel
The impact of automation is visible in all areas of industry as well as in everyday life. Automation makes the process control more efficient, increases productivity of work, manufacturing quality, decreases manufacturing costs. Automation is still in development so that it could succeed in filling all requirements of today’s technical advance. For this reason we daily meet new questions about implementation of automation systems, their handling and expanding. One of these is the question of communication in industrial applications. In case of having more PLCs in one industrial network, it is necessary to solve their inter-communication. We should deal with this question in dependence on some facts, for example: used control system, used industrial network, transmission reliability requirements and so on. In this article we would like to present a solution for inter-communication between PLCs in one industrial network by S7 communication. S7 communication via Industrial Ethernet allows program-controlled communication using communication SFBs/FBs via configured S7 connections.
Analysis of reconfigured control loop with a virtual actuator
(Vysoká škola báňská - Technická univerzita Ostrava, 2011) Filasova, Anna; Serbak, Vladimir; Gontkovic, Daniel
Control reconfiguration changes the control structure in response to a fault detected in the plant. This becomes necessary, because a major fault like loss of an actuator breaks the corresponding control loop and therefore renders the whole system inoperable. An important aim of control reconfiguration is to change the control structure as little as possible, since every change bears the potential of practical problems. The proposed solution is to keep the original controller in the loop and to add an extension called virtual actuator that implements the necessary changes of the control structure. The virtual actuator translates between the signals of the nominal controller and the signal of the faulty plants. This paper is concerned with the analysis of reconfigured loop with a virtual actuator for the system with the faulty actuator. The proposed analysis is illustrated on numerical example.

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