Text document clustering is a task that organizes text documents according to their semantic similarity. This paper focused on clustering Slovak text documents from Wikipedia into specific categories using different clustering algorithms such as agglomerative hierarchical clustering, divisive hierarchical clustering, K-Means, K-Medoids and self-organizing maps. These algorithms were compared according to several term weighting schemes such as TF-IDF (Term Frequency Inverse Document Frequency), residual IDF, Okapi and others. We also used PCA (Principal Component Analysis) to illustrate the document vectors in three-dimensional space. We used purity and entropy to evaluate the clustering results. The best results were obtained by agglomerative hierarchical clustering using TF-IDF as a term weighting scheme.

This paper provides approaches for day-ahead electricity price forecasting together with problems existing in this field mainly with nonlinear character of modelation. The fundamental model by using neural networks is shown and output results are presented, for example, failure of the model. Comparison with already existed models and other approaches for prediction of electricity prices are mentioned and carried out in this article. As evidence of the correct function of this method difference between real results of the spot market and output of the model is presented.

This paper discuss about long-term dynamics in simplified model of the power grid. This model represents Slovak power system connected trough inter-tie line to interconnected power system – ENTSO-E. The Slovak power system itself is represented by node SEPS. To this node conventional and renewable energy sources are connected. The significant growth of installed power capacity of renewable energy sources (RES) in the last few years may cause incidental disturbance of power balance in the power system. This problem is typical for photovoltaic power stations. It is very hard to predict photovoltaic (PV) power production especially during cloudy weather conditions. Because of this fact it is very important to determine maximum share of RES in each power system. This paper deals with impact of PV in power system.

In this paper the General Series Parallel Resonant Converters (GSPRC) is analyzed using state space techniques and the general mathematical model of the converters has been developed and simulated using MATLAB. The investigations on the series parallel resonant converter topologies such as CLL-T SPRC, LLC-T SPRC and LCL-T SPRC with closed loop operation has been estimated and presented. The comparative analysis of the converters and controllers is presented in this paper. A simple form of transfer function for the GSPRC is developed, which is used to analyses the stability of various resonant topologies. The simulation study indicates the superiority of fuzzy controller over the conventional control methods. A DSP based prototype of 300 W, 100 KHz converter is designed and experimentally demonstrated. The effectiveness of the proposed controller is verified for load and supply disturbance in experimental set up using TMS320F2407 processor. Comparison between experimental and simulations show a very good agreement and the reliability of fuzzy controller.

The Article deals with the use of the Saleh Valenzuela (SV) model in the UWB frequency band. It presents the calculation of the SV model parameters for receiving antenna depending on different positions of transmitting antenna. The calculated SV parameters are derived from the real measured external environment. The calculated parameters will be used for concluding the definition of the signal spread in the measured environment.

The aim of this paper is to provide an overview on pattern-based approaches. At first, it introduces the pattern-based strategies. Then, it explores disciplines and technologies to enable business leaders to advance. Advancement refers to shift from traditional information disciplines to seeking patterns of change (from people, process and information) and acting on them. It presents theories, frameworks and the properties available for the achievement of successful leading of the businesses during times of rapid and unpredictable change: Observe, Orient, Decide and Act (OODA) cycle and Pattern-Based Strategy (PBS). Also, it explores ways in which they complement. Lastly, it compares decision loop based on OODA with military Network Enabled Capability (NEC). It discusses how senior executives, planners and architects can apply OODA and PBS. Aforementioned is needed to speed up organizational decision making. Paper explores the possibility of coordinated response to change as well. It relates to organizations that are striving to be adaptable and describes the underlying technology.

This paper describes the impact of TCSC (thyristors controlled series compensator) on the transient stability of the electricity transmission. Line reactance and the power flow can be changed by TCSC. TCSC can help to better course of the transient phenomenon ongoing in the power system (PS). TCSC is the one of the best ways to improve the transient stability of the power transmission system.

Algorithms are central objects of every nontrivial computer application. Every programmer thus should have basic knowledge from the area of algorithm design in order to work more effectively. Simplifying and deepening the understanding of algorithms operation is the main goal of algorithm visualization. There is active research and development in the area of algorithm visualization in the last decades. Solutions of different quality and serving different purposes are available nowadays, but often it is not an easy task to modify or extend the particular solution to meet specific needs exactly. The paper contains concise overview of development in the area of software visualization, as well as a proposal of software visualization platform with the emphasis on its extensibility and portability.

This paper discusses the control of a new topology of a brushless doubly-fed induction generator (BDFIG) using back-to-back PWM converters and its application to variable speed wind energy generation. The BDFIG has gained renewed attention in variable speed drive applications in recent years for the features of simple structure, favorable characteristics and economical operation. The goal of BDFIG control is to achieve a similar dynamic performance to the doubly fed induction generator (DFIG), exploiting the well-known induction motor vector control philosophy. The performance of hybrid fuzzy proportional plus integrator conventional (HFP+IC) controller has been investigated and compared with the conventional PI controller based BDFIG. The simulation results show that HFP+IC controller is superior to PI controller under dynamic condition.