Communications - Scientific Letters of the University of Zilina, 2009 (vol. 11), issue 4
Articles
Multi-Threaded Ant Colony Optimization with Asynchronous Communications for the Vehicle Routing Problem
Maria Lucka, Stanislav Piecka
Communications - Scientific Letters of the University of Zilina 2009, 11(4):5-8 | DOI: 10.26552/com.C.2009.4.5-8 
In this paper we study behaviour of Ant Colony Optimization algorithm for solving the Vehicle Routing Problem implemented by POSIX Threads in parallel cluster environment. The algorithm is based on a fine-grained parallelism strategy which uses asynchronous communication for cooperation in finding solutions. Our aim is to analyze the effect of proposed method on speedup, execution and communication time with respect to the quality of solution.
Design of Compression Members for Durability
Josef Vican, Marian Sykora
Communications - Scientific Letters of the University of Zilina 2009, 11(4):9-14 | DOI: 10.26552/com.C.2009.4.9-14
General principles of structural elements design for durability and their application in the case of compression members are presented in this paper. The degradation effects of material deterioration due to corrosion cause the loss of member resistance, but the limit states method does not directly reflects design and verification allowing for failures caused by material deterioration. The time-dependent loss of compression member resistance was computed for specific corrosion models to express the time-dependent approximation function taking into account effects of corrosion degradation. Then, the design member resistance could be obtained using buckling...
Variance in a Second Language Pronunciation Quality
Zdena Kralova, Martin Krajcovic
Communications - Scientific Letters of the University of Zilina 2009, 11(4):15-23 | DOI: 10.26552/com.C.2009.4.15-23
The study assessed the relation between the overall degree of perceived foreign accent in non-natives' English speech and a variety of factors. Five native speakers of English were asked to auditorily evaluate the samples of free English speech produced by each of 99 non-native talkers using the equal-appearing interval scale. The 5-point scale was used to rate each of the variables for each non-native speaker and the interclass correlation coefficients were calculated to identify the most important predictors of foreign accent.
Radio Map Framework for GSM Positioning
Peter Brida, Jozef Benikovsky
Communications - Scientific Letters of the University of Zilina 2009, 11(4):24-27 | DOI: 10.26552/com.C.2009.4.24-27
This paper introduces radio map framework for creation of GSM (Global System for Mobile communications) network radio maps. These radio maps are structured in the way that they can be utilized later on as a data source for fingerprinting-based localization methods. Attributes of fingerprinting localization method as well as particular radio signal parameters are explained. The framework handles data measurement, data transfer and data visualization scenarios. Data are basically various radio signal parameters coupled with position coordinates. These data make up a database, which allows centralized storage and opens a path to service-oriented localization...
Analysis of Impact of the Different Node Architectures and Wavelength Channel Protection on the Availability WDM Ring Networks
Ivan Rados, Ladislav Schwartz
Communications - Scientific Letters of the University of Zilina 2009, 11(4):28-37 | DOI: 10.26552/com.C.2009.4.28-37
This paper investigates the availability of WDM (Wavelength Division Multiplying) ring networks. An analysis of different nodes, composed of passive and active components, is then carried out, as well as their availability. The availability for optical link, and especially the Span Protection and Route Diversity, is analysed as well. The wavelength channel protection principles being used in WDM ring networks are particularly explicated: OCh (Optical Channel) dedicated and OCh shared protection. The availability models for a WDM ring using these types of protection are given as well as the impact of availability for nodes and optical links on the entire...
Ant Colony Optimization Method and Split-Delivery Vehicle Routing Problem
Andrej Chu
Communications - Scientific Letters of the University of Zilina 2009, 11(4):38-42 | DOI: 10.26552/com.C.2009.4.38-42
This paper deals with a split delivery vehicle routing problem, which is a modification of a vehicle routing problem. It consists in delivery routes optimization in communications network containing initial city of all routes and a given number of places, which is necessary to include in delivery routes, where a customer can be served by more than one vehicle. The objective is to find a set of vehicle routes that serve all the customers and the total distance traveled is minimized. The split delivery vehicle routing problem is NP hard, therefore we present a solution approach by three heuristics, and a metaheuristics called Ant colony optimization (ACO).
Analysis of Factors Influencing Microstructure and Mechanical Properties of Austempered Ductile Iron
Alan Vasko
Communications - Scientific Letters of the University of Zilina 2009, 11(4):43-47 | DOI: 10.26552/com.C.2009.4.43-47
The paper deals with some factors influencing microstructure and mechanical properties of austempered ductile iron (ADI). Final structure and properties of ADI are obtained by exactly controlled process of heat treatment of nodular cast iron. The influence of conditions of isothermal heat treatment on microstructure and mechanical properties of austempered ductile iron, especially different temperature of isothermal transformation of austenite and different holding time at this temperature, is shown in the paper.
Properties of Strain-Gauge Load Cells Applied for Stator Reaction Measurement
Lubomir Miklanek
Communications - Scientific Letters of the University of Zilina 2009, 11(4):48-51 | DOI: 10.26552/com.C.2009.4.48-51
This contribution deals with experience with the measurement of the stator reaction of the dynamometer using load cells. Originally, the stator reaction had been measured using a balance mechanism. Within the framework of the author's research, it was necessary to improve the accuracy of torque measurement of the dynamometer. To accomplish this requirement, the old balance mechanism was replaced by a straingauge load cell. Two various types of the load cells were applied in order to arrange the measuring range to the expecting range of values of the torque. During the calibration, hysteresis in voltage output of the both applied load cells was observed....
How to Change the Travellers' Mobility Behaviours? - Examples of Mobility Plans
Katarzyna Nosal
Communications - Scientific Letters of the University of Zilina 2009, 11(4):52-55 | DOI: 10.26552/com.C.2009.4.52-55
The paper presents a mobility management concept as well as gives examples of mobility plans which are fundamental instruments of mobility management. A mobility plan includes activities for the promotion of sustainable mobility modes: bikes, public transport, walking trips and new means of private car usage (carpooling, carsharing systems). It also consists of solutions which realize an idea of sustainable transportation. Mobility plan activities allow to fulfill travellers' mobility needs and shape their mobility behaviours.
Problems and Key Factors of CRM Implementation
Viliam Lendel
Communications - Scientific Letters of the University of Zilina 2009, 11(4):56-60 | DOI: 10.26552/com.C.2009.4.56-60
CRM value chain identifies five key steps in the development and implementation of a CRM strategy: customer portfolio analysis, customer intimacy, network development, value proposition development, and manage customer life cycle. These five primary stages of the CRM value chain represent three main sequential phases of CRM strategy: analysis, resource development and implementation. This article deals with CRM value chain and diagnostics of the level of Slovak companies in the CRM area.
A Contribution to the Traffic State Estimation by Means of Image Processing
Marija Kopf, Petr Cenek
Communications - Scientific Letters of the University of Zilina 2009, 11(4):61-64 | DOI: 10.26552/com.C.2009.4.61-64
The success of traffic simulations depends largely on the simulation model validity and on accuracy of input data. For input data acquisition, video cameras are used to survey the traffic at junctions or at other places along the road to collect video data. The velocity, distance between the vehicles, acceleration and other relevant parameters can be extracted from the collected data. The estimated values are used for calibration of the simulation model. The data that has to be collected for calibration or validation of the simulation system, differ from country to country and reflects the driver behavior. For that reason, the data collection must...
General Vectorization of Line Objects in Drawn Maps
Peter Tarabek
Communications - Scientific Letters of the University of Zilina 2009, 11(4):65-68 | DOI: 10.26552/com.C.2009.4.65-68
Drawn maps consist of multiple object types. The most important are line objects which represent infrastructure. Attributes of these objects are essential for many tasks but in raster format they provide only low level information. Vectorization must be used to obtain vector data. In this paper general vectorization process consisting of five stages is proposed. For these stages short discussion and basic recommendations are given and some proper methods are presented.