EEEP 4/ 2019

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Boris Mihaylov, Ana Piskova

Summary: The recent paper presents in brief the realized from spectri ltd. project for creating Strategic Noise Maps for Sofia Airport (approved in 2019). Bellow are cited the used methodology and instrumentation. In brief are shown the overall final results, and the main conclusions out of them. The input data were taken both from ATSA theoretical data, and from airport noise monitoring and flight tracking system. Calculation have been verified with real on cite measurements, maintained last 5 years. Overall results show low noise impact of the airport to Sofia city for the integrated noise indexes, and limited local impact re. LAmax results.

Keywords: noise, noise map, airport




Dobriyan Benov, Diyana Benova

Abstract. Contemporary big city (urban agglomeration) is the noisiest place for work and/or dwelling chosen by a considerable part of mankind. We should also note that noise is (1) extremely aggressive and widespread form of pollution of urbanized environment, and (2) the growth of urban population and their mobility lead to an increase in noise, including the emergence of new sources.

After stating the diversity of noise sources in cities most researchers put in the first place the impact of traffic noise. This is determined by the increasingly developed street network, increase in number of automobiles, irrational traffic organization and other suchlike factors. However, there are some other noise sources, some of them related to the specific nature of urban life that should not be underestimated.

This material is a summary of some applications of the Monte Carlo method in urban acoustics, and in particular the determination of the noise characteristics of different types of noise sources and the prediction of the propagation of sound waves.

Keywords: Monte Carlo Method, urban acoustics, noise characteristics, quazi-cylindrical sound wavs


Antibiotic resistance of microbiome in natural waters and waters unfer anthropogenic impact

Zvezdimira Tsvetanova, Hristo Najdenski

Abstract. Increasing bacterial resistance to antibiotics is considered to be one of the major threats to public health. Despite linking the problem mainly with the clinical pathogens, there is increasing evidence of interrelations of antimicrobial resistance with the anthropogenic impact on water environment. The review discusses the the spread of antibiotic resistance among bacterial communities in drinking water, surface water and wastewater. The available data on the content of residual antibiotics, antibiotic resistant bacteria and antibiotic resistance genes as emerging contaminants in water environment are summarized.

Key words: antibiotics; antimicrobial resistance; antibiotic resistant bacteria; antibiotic resistance genes; natural waters; wastewater



Zahari Zarkov

Abstract: The article presents the authors experience in the field of wind turbine emulator design for physical modeling of wind energy conversion systems (WECS). The wind turbine is replaced by DC motor with electronic converter controlled with a microcontroller. An appropriate real-time software is developed for control of the motor torque and speed in order to follow wind turbine mechanical characteristics for different wind speeds. The software is based on a mathematical model of the wind turbine and a PI controller with speed and motor current or torque feedback. Mathematical models, block diagrams and experimental study present two different wind turbine emulators developed by the author. The results prove that the approach to replace a wind turbine by DC motor drive with appropriate control is working and gives good results. The wind turbine emulators give the possibility to study the processes in WECS in laboratory conditions without having real wind turbine.

Keywords: Wind turbine emulator, DC motor drive, Wind energy conversion systems, Wind turbines

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 I. Simeonov, S. Mihajlova, D. Galabova, N. Kostadinova, V. Akivanov

 Abstract. The paper deals with anaerobic digestion (AD) of three types of lignocellulosic waste (corn stalks, wheat straw and barley straw) in a pilot bioreactor under batch and continuous operation modes. Corn stalks were termochemically pretreated with NaOH at 55C for 24 hours (Experiment 1), wheat and barley untreated straw (Experiments 2 and 3) and barley straw treated with fungi fungal strain Trametes trogii, representative of Phylum Basidiomycota (Experiment 4). The organic load used was 10 g/L. Biogas yield and concentrations of methane and carbon dioxide in the biogas were measured on a daily basis, as well as organic dry matter at the beginning and end of the batch experiments. The results show that the pretreatment of lignocelluloses waste results in a significant increase in the specific yield of both biogas and methane. The concentration of the two major gases is practically the same - 56% methane and 43% carbon dioxide. In Experiments 2 and 3, the specific yields of biogas and methane were 0.204 L biogas/g organic dry matter and 0.110 L methane/g organic dray matter for wheat straw and 0.240 L biogas/g organic dry matter and 0.120 L methane/g organic dray matter for barley straw, respectively. The highest specific yield was obtained with corn stalks treated with sodium base (0.625 L biogas/g organic dray matter and 0.340 L methane /g organic dray matter), followed by barley straw treated with fungi (0.480 L biogas/g organic dray matter and 0.252 L methane/g organic dray matter).

            The AD of untreated wheat straw in a continuous mode of operation (manual and automatic feed of the substrate) at organic loads of 10 and 15 g/l was also investigated. Some improvements of the automated pilot biogas installation of the Stefan Angelov Institute of Microbiologists, BAS are presented.

 Keywords: anaerobic digestion, lignocellulosic waste, chemical treatment, batch mode, continuous mode



Simeon Bogdanov

Abstract. The paper presents results from study on Brown Forest soils (Dystric - Eutric Cambisols) and Darkcolored Forest soils (Umbric Cambisols) under high productive spruce stands (Picea abies (L.) Karst.). They are situated in the Middle forest vegetation zone (700 2000 m a. s. l.) of the Tracian forest vegetation area. The factors of soil formation and the soil properties have been analyzed. A dendrometric study of the stands has been made in order to determine their productivity. The data obtained show conformity between soil properties and forest productivity as well as possibilities to create mixed-species forests.

Key words: forest soils, factors of soil formation, soil properties, spruce stands.