ecological systems
G. Mihalev, S. Yordanov, H. Stoycheva. Beehive Condition Monitoring System Intended for Application in Beekeeping

Key Words: Beehive monitoring system; precision beekeeping.

Abstract. Honey bees are one of the most important insects for human existence. They have a main role in the production of various agricultural crops, as well as in the development of nature itself. Currently, bee colonies are facing many problems related to climate change, diseases, chemical pollution and most of all human activity regarding the development, production and sustainability of the bee colony. The aim of the present development is to provide a solution or at least to partially suppress certain problems of bee families during their development in their active period, with a minimum expenditure of resources. These problems can be summarized as problems related to the health of the hive, problems related to reproduction and problems related to the production of certain bee products (honey, pollen and wax). A system for monitoring of some bee colonies parameters in real time is proposed, based on cloud services and a microprocessor system with a set of sensors. The obtained information can help the beekeeper take timely action with minimal stress to the bees in the colony. The developed system is based on an ESP32 microcontroller and measures basic parameters, such as internal and external temperature, humidity and weight of the beehive. The data is stored in a cloud structure with a good graphical presentation environment for the purpose of subsequent analysis. Attention is paid to energy saving and communication in difficult to reach places and regions. The architecture of the system and its implementation are described in details. The developed system can be used to monitor the production of honey, prevent the process of swarming, as well as to maintain a high health status of the bee colonies. Results of actual data obtained for the observed values during the active period of development of a beehive are presented. Through the technical and economic analysis, information is given about the achieved socio-economic results.

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ecological systems
K. Boshnakov, B. Koumanova, M. Varbanov, E. Mihailov. Procedure for Analysis and Assessment of Water Quality in the Struma River

Кey Words: Neural classifiers; state of river waters; Struma river; presence of inadmissible pollution.

Abstract. The aim of the present work is to study the possibilities for developing a system for monitoring the state of the water on the Struma River and the presence of unacceptable pollution. The development of the algorithms of the monitoring system is in accordance with the normative documents of the Republic of Bulgaria and is built on the basis of monitoring measurements for the quality of the river waters from six monitoring points for the period 2010-2019. The following variables characterizing water quality were analyzed:
ammonium nitrogen (NH4-N), nitrate nitrogen (NO3-N), nitrite nitrogen (NO2-N), pH, biological oxygen demand (BOD), electrical conductivity (EC), total nitrogen (TN), total organic carbon (TOC), total phosphorus (TP), orthophosphate phosphorus (PO4-P), dissolved oxygen (DO), temperature (T) and chemical oxygen demand (COD).
The section of the river Struma from before Blagoevgrad to the border (bridge for the village of Topolnitsa) was chosen for the research. The available measurement data from six monitoring points in the considered section of the Struma River are as synchronized as possible.
Correlation analyzes were performed for the possibility of combining the available measurements from the six monitoring points and for the presence of a correlation dependence between the measured variables characterizing the water quality in the Struma River. The presence of correlations between the variables directs the use of the principal components method as a mathematical apparatus for building the monitoring system. Procedures have been developed for classifying the status of river waters depending on current measurements / analyzes. Expressions for the main components for eleven of the measured variables characterizing water quality are derived.
Research has been carried out to develop a procedure for classifying these measurements into the terms “excellent”, “good” and “moderate”.
Possibilities for classifications with neural networks have been studied. Measuring some of these variables is a lengthy procedure and can hardly be used for operational actions. For this reason, the possibilities for developing a procedure for monitoring and classifying the status of river waters on the basis of variables, which in principle can be measured automatically (pH, EC, DO and T), have been explored. They also apply the principal components method and classification with neural networks in the same classification categories.
The developed approaches for monitoring the quality of the waters of the Struma River can be applied for each measurement in the six monitored monitoring points.

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ecological systems
S. Kasabov, E. Kirilova. Application of NIR Spectroscopy Combined with Chemometric Modelling Methods for Environmental Analysis of Contamined Soils

Кey Words: NIR spectroscopy; chemometric methods; environmental analysis; contaminated soils.

Abstract. Conducting quantitative analysis of soil properties and contaminants in them is a crucial for an achievement of a good understanding of dynamics of ecosystems and a sustainable soil management.
This study presents the recent progress on the developed combined approaches including NIR spectroscopy and chemometrics for accurate, low-cost and reliable quantitative analysis of soil content, published in prestigious journals for the last 7 years. A classification of the approaches depending on the types of soils components, the type of applied pre-processing and chemometric methods
is done. Their main advantages and disadvantages are shown and some trends for future development are outlined.

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