Communications - Scientific Letters of the University of Zilina, 2009 (vol. 11), issue 3
Articles
A Security Model for an Operating System for Security-Critical Applications in Small Office and Home Environment
Jaroslav Janacek
Communications - Scientific Letters of the University of Zilina 2009, 11(3):5-10 | DOI: 10.26552/com.C.2009.3.5-10 
Personal computers are often used in small office and home environment for different purposes ranging from general web browsing and e mail processing to processing data that are sensitive regarding their confidentiality and/or integrity. Common operating systems do not provide sufficient protection. We present asecurity model combining the well known benefits of mandatory access control in classified information processing systems with the typical home and small office computer use. We use a simple two-dimensional data classification scheme and present a security model with provable properties that significantly reduces the risks of confidentiality...
A Multi Label Algorithm for K Shortest Paths Problem
Stanislav Paluch
Communications - Scientific Letters of the University of Zilina 2009, 11(3):11-14 | DOI: 10.26552/com.C.2009.3.11-14
The paper presents an algorithm for computing k shortest walks or k shortest paths in a directed graph G (V, A). The proposed algorithm can be applied for solving the k shortest paths problem in an undirected graph G (V, E), too, by transforming the graph G (V,E) to the digraph G(V, A) where the arc set A contains a couple of arcs (u,v), (v,u) for every edge {u,v} E.
Parallel Backtracking Algorithm for Hamiltonian Path Search
Karol Grondzak, Penka Martincova
Communications - Scientific Letters of the University of Zilina 2009, 11(3):15-19 | DOI: 10.26552/com.C.2009.3.15-19
The speed of calculations is a common problem to tackle in many areas of scientific research and real life. This paper presents an implementation of a parallel backtracking algorithm. The performance of the proposed algorithm is demonstrated on the problem of Hamiltonian Path search. Obtained results exhibit significant improvement of the parallel algorithm over the sequential one. Different aspects of parallelization of backtracking algorithm are studied and presented.
Heuristics for the Solution of a Very Large Street Routing Problem with Mixed Transportation Mode
Peter Matis
Communications - Scientific Letters of the University of Zilina 2009, 11(3):20-24 | DOI: 10.26552/com.C.2009.3.20-24
Servicing a large number of customers in a city zone is often a considerable part of many logistics chains. This problem is called a Street Routing Problem (SRP). As presented, only using systems such as Geographical Information Systems (GIS) it is possible to effectively manage SRP. New heuristic for solving a very large SRP is evaluated on the real data. One of the key properties of GIS for use with the routing software is its flexible interactive and user-friendly environment. The paper presents several approximations of length for SRP with mixed transportation mode.
Solution of the Bus Route Design Problem
Vladimir Pribyl
Communications - Scientific Letters of the University of Zilina 2009, 11(3):25-28 | DOI: 10.26552/com.C.2009.3.25-28
The paper deals with a single bus route design problem. It consists of two stages. The first one is to choose the set of stops fulfilling a defined constraint. The second one is the precising of the order of the stops on the route. Both exact and heuristic methods are proposed and verified on 9 randomly generated networks. Very high computational complexity of the exact method and some ways how to reduce it are discussed in the paper. Comparison of the experimental results is presented in the final table.
Optimal Evacuation Plan Design with IP-Solver
Jaroslav Janacek, Michal Sibila
Communications - Scientific Letters of the University of Zilina 2009, 11(3):29-35 | DOI: 10.26552/com.C.2009.3.29-35
This paper deals with two different computer-supported approaches to an evacuation plan design, which should assign the available vehicles to endangered dwelling places so that the total time of evacuation is minimal. It is assumed that some safe place is pre-assigned to each endangered dwelling place and there are determined locations of homogenous fleets of available vehicles, which can be used for transport of the endangered population from their dwelling places to the pre-assigned places. In this paper, we suggest and compare two approaches to the evacuation plan design. The first approach assigns all vehicles of a fleet to one evacuated dwelling...
Pickup and Delivery Problem
Jan Pelikan, Jan Fabry
Communications - Scientific Letters of the University of Zilina 2009, 11(3):36-38 | DOI: 10.26552/com.C.2009.3.36-38
Vehicle routing problem and traveling salesman problem are classical problems in operational research; this modification of those problems consists of a transport among nodes of the communication network using cyclical routes of vehicles with a given capacity. A transportation demand is given by the place of pickup, the place of delivery and quantity of goods. The goal is to find cyclical routes of a minimal length which ensure the transport requirements. In the paper there are two models proposed for the problem, both are demonstrated on an example. The problem is based on a case study from practice.
Minimal Total Area Convex Set Partitioning Problem
Stefan Pesko
Communications - Scientific Letters of the University of Zilina 2009, 11(3):39-42 | DOI: 10.26552/com.C.2009.3.39-42
The linear binary model for finding set partitioning of the points in the plane is studied. We present heuristic which generates partitioning of points to clusters for a given number of seeds with searched seeds of clusters in a plane. For this cluster the convex hulls are constructed via Graham's scan algorithm. This approach is demonstrated on the real instance of Florida area with 235 points for 10 and 13 clusters.
A Contour Approach to Thinning Algorithms
Peter Tarabek
Communications - Scientific Letters of the University of Zilina 2009, 11(3):43-48 | DOI: 10.26552/com.C.2009.3.43-48
Thinning algorithms are widely used in many image processing tasks. Many thinning algorithms were proposed but they usually tend to process all image pixels in every iteration. Two approaches to contour thinning are described and a short discussion about their features is given. These approaches can be implemented as sequential or parallel algorithms with different deletion rules. Results of comparison and analysis are presented in this paper.
Mathematical Formulas in Text to Speech System
Peter Caky, Juraj Boron, Martin Klimo, Katarina Bachrata
Communications - Scientific Letters of the University of Zilina 2009, 11(3):49-53 | DOI: 10.26552/com.C.2009.3.49-53
A modular based system for synthesis of a written text allows solving partial problems separately. If there is designed a logical structure with clear interfaces, it could be possible to prepare modules for variant processes by different members of the team, without necessity of the coordinated work. The paper deals with amodule for engine reading of mathematical formulas in aSlovak text-to-speech system. The problem consists in the conversion of formulas to the written text in Slovak language and consequently additional conversion to the phonetic form. The main idea is to use the markup language LaTeX.
Algorithm for Generating Text Descriptions of Bit Calendars
Hynek Bachraty, Emil Krsak, Marek Tavac
Communications - Scientific Letters of the University of Zilina 2009, 11(3):54-62 | DOI: 10.26552/com.C.2009.3.54-62
The article deals with the problematics of generating calendar text descriptions based on their bit map. We introduce the description of the algorithm we have designed, its basic ideas and parts. We also present the results of testing the successfulness of the algorithm before it is primarily used.
Methods and Techniques for Design of Effective and Competitive Single Wagon Load Transportation
Michal Kohani, Peter Marton
Communications - Scientific Letters of the University of Zilina 2009, 11(3):63-67 | DOI: 10.26552/com.C.2009.3.63-67
European freight railway operators are losing money with their single wagon load transportation activities. Closing down this business segment does not appear to be a valid option, since single wagon load transportation is connected with full train load business and intermodal traffic. This paper presents methods and techniques that were chosen to solve different problems of single wagon load transportation.