Journal Issue: 1/2013

The first Issue in the year 2013 of the journal ICCST is out. In the Issue you can read about the state of the art Bulgarian scientific researches by the leading researchers in many subject areas.

A Quality Evaluation of Fruit and Vegetables based on their Spectral Reflectance and Transmittance Characteristics

Authors: Chavdar Damyanov, Tanya Titova, Veselin Nachev

This paper is concerned with the use of on integrated approach to select of informative characteristics of spectral reflectance and transmittance on whole fruits and vegetables, suitable for building of quality evaluation and classification models.          For this purpose, the sensory block consists of a photometric camera which scans one-by-one every product that goes through it. The scanned products are analysed on the basis of their spectral reflectan...

An Algorithm for Synthesis of Families of Frequency Hopping Signals with Ideal Periodic Correlation Properties

Authors: Mihail Iliev, Borislav Bedzhev, Tihomir Trifonov, Lilia Staneva

A key role for the present wireless communications plays the families of signals with low periodic correlation. With regard in the paper an algorithm for synthesis of families of frequency hopping signals, possessing ideal periodic correlation properties, is suggested. The algorithm is very effective from the computational point of view and could be successfully applied in the design of wideband signals with complex inner structure, which are suitable for the perspective communication systems, p...

PAPR Reduction of OFDM Signals by PTS with Recursive Phase Weighting Method

Authors: Mihail Iliev, Viktor Hadzhivasilev, Rumen Rusev

One of the challenging issues for Orthogonal Frequency Division Multiplexing /OFDM/ system is its high peak-to-average power ratio /PAPR/, which causes serious degradation in performance when a nonlinear power amplifier /PA/ is used. Partial Transmit Sequence /PTS/ is one of the most attractive schemes to reduce the PAPR in OFDM systems. However, the conventional PTS technique requires an exhaustive searching over all the combinations of the given phase factors, which results in the computationa...


Authors: Stoyan Yanev, Ivaylo Stoyanov and Valentin Stoyanov

In this article is presented an overview of the existing solutions for smart grids, presents several modelling criteria, which are graded according to the type of consumer. The purpose of this article is to define the most suitable design criteria for the modelling of a Smart Grid (SG) using a photovoltaic power source and supplying a data server. In the proposed SG design, is aimed at making the operation of the system as simple as possible from the viewpoint of controls and communication using...


Authors: Miroljub Mladenov, Martin Dejanov, Stanislav Penchev

The paper presents some investigations held in assessment of grain quality features using color image and spectra analyses. Methods and tools are presented to obtain visible features like color, shape, and dimensions extracted from grain images. Color and surface texture is obtained from the grain spectral characteristics to specify object features. Two data fusion approaches are used for the final classification of grain samples in three quality groups. The first fusion technique is related to ...

Dynamic models for apricots drying using genetic algorithm

Authors: Donka Ivanova, Nikolay Valov, Valentin Stojanov

Drying kinetic of apricots was investigated under different conditions. The drying experiments were performed at air temperatures of 50÷80°C and air velocities of 0.5÷2m/s. Fourteen different mathematical drying models were obtained by using regression analyses. The modified Page model was found most suitable for predicting the drying of apricots. The obtained modified Page model was optimized by genetic algorithm. It was compared the reduced chi-square, mean bias error and roo...


Authors: Lyuben Iliev, Nikolay Panteleev, Nikola Mihaylov

Electronic devices can legally be sold on the market only if they correspond to the standards of electromagnetic compatibility (EMC). In order to shorten the process of development and to lower the expenses required for multiple tests, it is convenient to use simulation for EMC. The current paper shows a simulation of the conducted emissions in the power supply network from switched mode power supply for LED lighting systems. The simulation is made using the CST STUDIO software product and the r...

Evaluation of pork freshness by computer vision

Authors: Zlatin Zlatev, Mirolyub Mladenov

The feasibility of computer vision as a rapid and non-destructive method for assessing the quality of pork is exposed in the report. The changes of color of meat preformed bought from sales network for a period of 3, 5 and 7 days are monitored. An assessment of the information value of the color features from different color models is done. The results of the measurements show a high correlation between the change in pH and color of the meat samples and change the values ??of the color component...

Recognition and Grading of Sound and Fusarium Damaged Corn Seeds of Different Varieties using Prototype System based on Machine Vision

Authors: Eleonora Kirilova, Plamen Daskalov, Tzvetelina Georgieva, Rusin Tzonev

A prototype system for recognition and grading of corn seeds with external signs of Fusarium Moniliforme disease has been reported in this paper. The system could continually present one by one positioned corn kernels to CCD camera, perform a classification procedure of captured images and discharge seeds to assigned containers. The software was developed in the LabVIEW environment to provide graphical and user–friendly interface, while image analysis and classification procedures, includi...

Conceptual Model of Virtual Reality System

Authors: Stoyan Maleshkov,

Conceptual model for describing the essential components, the structure at appropriate level of details, the relationship between the major building blocks and the mode of operation of a virtual reality (VR) system  is presented in this paper. The model represents the interrelation among the basic elements of the VR system: output devices, rendering subsystem, input derives for tracking user position and interacting with the virtual environment, and  database for building and maintaini...

The quality of color-to-gray conversion for medical images: A new metrics for its evaluation.

Authors: Desislava Georgieva,

The aim of this paper is to present a new quality metrics for digitized X-rays c color-to-gray conversion. Discussed are several methods for color-to-grayscale converting as well as some aspects concerning the postprocessed images quality. The new metrics is mainly oriented towards medical applications.

Design and Modeling of a Single-Ended High-Frequency Amplifier Stage for 28 MHz

Authors: Boyan Karapenev,

This paper presents the design and modeling of a single-ended high-frequency amplifier stage with a bipolar transistor for 28 MHz. Some powerful radio-frequency bipolar transistors operating at a large input signal are modelled. The simulation results of the modeled bipolar transistor and amplifier stage were obtained using Electronics Workbench Pro software. The obtained simulation results - oscillogram of input and output signal, amplitude-frequency and phase-frequency responses and some basic...

Increasing student’s engagement and motivation with game-based education – theoretical overview

Authors: Valentina Voinohovska, Svetlozar Tsankov

This paper is related with a research developed in collaboration by three higher education institutions – University of Ruse, New Bulgarian University and South-West University "Neofit Rilski". The research is supported by National fund: Bulgarian science fund, project ????-?01/10. The major objective of the project is to research innovative methods for assessing competence in e-learning environments. The specific article presents a pedagogical rationale for the use of educational computer...