H. Najdenski 3-4
I. MAN
AND BIOSPHERE
Strategic noise mapping for Sofia
airport
B. Mihaylov, A.
Piskova
5-16
D. Benov, D. Benova
17-29
Z. Tsvetanova, H.
Najdenski
30-43
Simulation
of the
wind turbines’ operation in laboratory conditions
Z. Zarkov
44-53
I. Simeonov, S.
Mihajlova, D. Galabova, N. Kostadinova, V. Akivanov
54-65
S.
Bogdanov
66-72
THE
ROAD OF
A DREAM: 50th Anniversary
of Space
Research
and Technology Institute - BAS
R.
Nedkov 73-78
STRATEGIC NOISE
MAPPING FOR SOFIA AIRPORT
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
Zvezdimira
Tsvetanova, Hristo Najdenski
Key words: antibiotics; antimicrobial resistance; antibiotic
resistant bacteria; antibiotic resistance genes; natural
waters; wastewater
SIMULATION
OF THE WIND TURBINES’ OPERATION IN LABORATORY
CONDITIONS
Zahari Zarkov
Abstract: The article presents the author’s 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.
ANAEROBIC
DIGESTION OF LIGNOCELLULOSIC WASTES IN A PILOT SCALE
BIOGAS PLANT
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 55°C 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.
SOIL CONDITIONS
UNDER HIGH PRODUCTIVE SPRUCE STANDS
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.