June 2006, Volume 6, Number 2
Summary: 
VACHTL, D., KOVÁČ, D., MAYER, D.: Forces Calculation Method of Thompson Levitating Ring During Its NonHarmonic Feeding [full paper] The work represents a contribution to a part of graduate course devoted to magnetic levitation. It deals with computation of electromagnetic levitation force acting on the Thompson ring in case of its steady state nonharmonic feeding. The theoretical analysis was verified on a demonstration device in common with simulation of its magnetic parameters. The results obtained on the basis of theoretical and simulation analyses were validated by measurement.

CHOCHLÍK, M., MATIAŠKO, K.: Interfaces and Adapters to Databases Using Standard Template Library [full paper] This paper presents a set of interfaces and cooperating adapters that greatly simplify the access to datasets, which are the result of a query to a database system in applications developed in the C++ programming language. These interfaces isolate the implementation of the database system from the client code and the adapters allow accessing the records of the dataset, in a more natural way, as native C++ structures possibly using the algorithms from the C++ Standard template library
(STL).

CIMBALA,
R.: The Calculation of Polarization Spectrum and Activation Energy of Insulation During Accelerated Thermal Stress [full paper] One of the cardinal properties of the insulation system of the electrical equipment is its electrical strength. Usually it is expressed as value of breakdown voltage. There is not electrical destruction of material under this one. The determination of breakdown voltage exactly is possible only by doing electrical strength test. It is a destructive test on insulation system made by solid material. This test is not suitable for service condition. There isn't only one test method that can complex diagnose the state of insulation system. The utilization of set of diagnostic methods is necessary. The biggest meaning in monitoring of high voltage insulation system ageing consists in methods based on regular nondestructive diagnostics. The analysis of results from several diagnostic methods is the principle. The issue of such diagnostics is detailed information about ageing process of insulation system of high voltage equipment. The high voltage motor is a very important element in the production process. A breakdown of its insulating system may cause a loss to the production. Therefore the importance of measuring and testing of its electrical properties is increasing more and more in conjunction with advances of power engineering equipment. This paper describes the use of polarization spectrum determination for diagnostic purposes, especially for insulating systems of high voltage machines. The study of absorption current during accelerated thermal degradation is presented in this paper. Absorptive currents are analyzed. The thermal behavior of a simple model of multilayer insulation material based on ReMica is described together with recommendation for practical utilization. The activation energy during accelerated thermal stress is calculated and analyzed.

KLIMEŠ,
C., PROCHÁZKA, J.: New Approaches in Software Development [full paper] In the last few years we can meet modern approaches and concepts like agile methodologies, extreme programming and modeldriven development in software development. These new approaches use methods and technologies that allow us to deliver valuable software products matching all requirements in time as well as decrease the cost of system operation and maintenance. Paper deals with some of these approaches. Technical managers, developers and also management should have at least brief knowledge of them because they can bring time and budget savings mainly in maintenance phase.

NOVITZKÁ,
V.: Church’s Types in Logical Reasoning on Programming [full paper] In our previous paper [1] of this series we defined the basic types as the startpoint of scientific problem solving by help of logically and mathematically founded programming of mathematical machines. In this paper we extend the type system with Church's types that enable the first step of problem solving during logical reasoning.

Wieser,
V.Pšenák,
V. The Performance of SIR–Based Hybrid Link Adaptation Algorithms in Mobile Radio Networks [full paper] In this article we have described and simulated new SIRframe based link adaptation algorithms. Algorithms were designed to increase efficiency of data transmission among user equipment and base stations (uplink). Simulation results of hybrid adaptation (power and modulation BPSK, QPSK, 16QAM, 64QAM) are compared and expressed as data throughput and outage probability for different simulation environments (pedestrian channel with mobile subscriber speed 10 km/s and vehicular channel with speed 120 km/h).

Drutarovský,
M., Šimka, M.Fischer,
V.: Comparison of Scalable Montgomery Modular Multiplication Implementations Embedded in Reconfigurable Hardware [full paper] This paper presents a comparison of possible approaches for an efficient implementation of Multipleword radix2 Montgomery Modular Multiplication (MM) on modern Field Programmable Gate Arrays (FPGAs). The hardware implementation of MM coprocessor is fully scalable what means that it can be reused in order to generate longprecision results independently on the word length of the originally proposed coprocessor. The first of analyzed implementations uses a data path based on traditionally used redundant carrysave adders, the second one exploits, in scalable designs not yet applied, standard carrypropagate adders with fast carry chain logic. As a control unit and a platform for purely software implementation an embedded softcore processor Altera NIOS is employed. All implementations use large embedded memory blocks available in recent FPGAs. Speed and logic requirements comparisons are performed on the optimized software and combined hardwaresoftware designs in Altera FPGAs. The issues of targeting a design specifically for a FPGA are considered taking into account the underlying architecture imposed by the target FPGA technology. It is shown that the coprocessors based on carrysave adders and carrypropagate adders provide comparable results in constrained FPGA implementations but in case of carrypropagate logic, the solution requires less embedded memory and provides some additional implementation advantages presented in the paper.

POČTA,
P., VACULÍK, M.: Determination of Optimal Test Sequence for Intrusive Measurement of VTQoS in Mobile Environment [full paper] This paper describes simulations of a test sequence transmission for intrusive measurement of VTQoS in mobile environment. The aim of the simulation was to analyze an influence of multipath signals propagation and propagation attenuation on the test sequence. Evaluation the generated sequences was based on the calculation of mean square measure and correlation coefficient. These measures were used as a criterion for suitable test sequences selection. Reconsideration of an influence of mobile environment on the test sequences, which are composed from simple signals, is the aim of this paper.

MACHOVÁ,
K., KLIMKO, I.: Classification and Clustering Methods in the Decreasing of the Internet Cognitive Load [full paper] The paper focuses on solving the problem of Internet users' cognitive load decrease based on machine learning methods. It presents the AWS system designed to suggest Web pages. Users are provided with system's suggestions based on their models. The AWS system is based on both classification and clustering machine learning methods. In addition, the system is able to generate information about visitor stereotypes. The system offers information about visitor models for the purpose of server content management. With the help of this information it is possible to customise the content of a server to user needs. The AWS system is an advisory system with offline learning capabilities. It enables both so individual adaptation and the support of global server content adaptation.

KRSTIĆ,
D. S., STEFANOVIĆ, S. Č., MARTINOVIĆ, D.: The Bit Error Probability of PSK System in the Presence of Interference and Noise [full paper] In this paper the bit error probability rather than the lower bound for two interferences is evaluated. The signal, interferences and noise are applied at the input to the phasecoherent communication receiver and an expression for the bit error probability is derived for the case when the reference carrier is not ideal. The analyzed model of the phase locked loop (PLL) is nonlinear. The reference carrier is extracted by the first and second order loop.

BENDIABDELLAH,
A., BACHIR, G.: A Comparative Performance Study between a Matrix Converter and a ThreeLevel Inverter Fed Induction Motor [full paper] In spite of the use of multilevel inverters for industrial high power applications, there has been considerable interest in the potential benefits of matrix converter technology, especially where size and longterm reliability are important factors.

GRINČOVÁ,
A., KRAVECOVÁ, D., KUDLÁČ, M.: Alternative Approach to Data Network Optimization [full paper] This paper offers another than standard view of solving the optimization problems occurring in practice. For description of a given problem we will take a suitable mathematical model which uses the graph theory and the theory of computing complexity. The introduction explains basic terms and it contains the most widely known standard combinatorial problems on graphs. The next chapter describes a particular practical problem. The problem is to find an optimal distribution of the data network among single offices and components of self government when we consider more providers of telecommunication connections and various technical conditions of data transmission. We will transform this problem into one correspondent mathematical model. In this mathematical model, the graph and the used objective function will represent the given network with all its conditions, requirements and also with its limitations. We will find the solution of this optimization problem by solving this mathematical model through the use of known algorithms. The goal of this paper is to show that this alternative approach to the given problem offers more simple and more elegant solution in comparison to solutions of some practical problems using standard optimization methods which can be slow and complicated.
