bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bin weather data of Varna and their influence on the seasonal efficiency of heat pumps with energy source outdoor air
Authors: Chakyrova D , Doseva N , Kalcheva N 
Published: January 2021

Abstract
The seasonal transformation coefficient (SCOP) of a heat pump with a heat source outside air as a function of the temperature of the latter is studied. The bin method was used to determine the climatic data for the city of Varna. Outdoor air temperature data were used and statistical analysis of the data was performed. The average frequency and cumulative distribution of temperature bins values in the period from 2005 to 2019 in the city of Varna is calculated. The results are presented using graphs and tables. In the data stability assessment report, the standard deviation and coefficient of variation were used. The SCOP of a heat pump heating installation operating in Varna has been calculated. All results were compared with those of other studies of the authors under different conditions and with reference data.
Achievement of maximum energy efficiency through vector control of induction motor electric drive
Authors: Rachev S , Ivanova G 
Published: January 2021

Abstract
Electric motors are the predominant driving devices globally, consuming electricity. For this reason, research aimed at minimizing their energy consumption is very relevant. The paper concerns an applied energy-saving method - vector control of an induction motor. With regard to this, a necessary condition for achieving maximum efficiency is to choose the optimal value of the magnetizing current. If the magnetizing current is not controlled properly, the result may be higher electricity consumption from a frequency-controlled motor than that of a direct-on-line power supply. In this case, a specific electric drive with certain parameters is analyzed. The research is based on a mathematical model, representing a system of differential equations, which is transformed and solved by appropriate software. The aim is to look for a minimum of electrical power losses. The physical side of the topic is treated exclusively without analyzing the economic benefits of the introduction of energy saving measures.
Influence of buoyancy forces in multi-storey buildings on the efficiency of a regenerative air handling unit with heat recovery
Authors: Penev A , Tsokov L 
Published: January 2021

Abstract
Various solutions are currently being offered to modernize the ventilation in old residential buildings. In small apartments, it is very appropriate to use decentralized ventilation units - for example with regenerative heat exchangers. Theoretical and experimental studies of such devices show a significant impact of the operational mode of regenerators (determined by the environment) on their efficiency. The aim of this article is to demonstrate the impact of the buoyancy forces in multi-storey buildings on the efficiency of a regenerative air handling unit for decentralized residential ventilation with heat recovery. Numerical solutions are presented for close to the real operating modes, airflow rates and air temperatures of the supply and the exit air, and the temperature ratio.
Hydraulic power take off system for wave energy utilization
Authors: Velichkova R , Pushkarov M , Angelova R A , Simova I , Markov D , Denev I , Stankov P 
Published: January 2021

Abstract
Wave energy from seas and oceans is among the most promising and abundant energy sources on the Earth. There are different designs of conversion systems for the utilization of the wave energy, resulting from the different ways of the wave energy absorption, and depending on the location characteristics. The paper proposes a new hydraulic power take-off system (PTOS) that can be used in various types of wave energy conversion systems.
Experimental investigation of the refrigeration cycle of water-to-water heat pump
Authors: Kolev Z D , Mushakov P G , Kadirova S Y 
Published: January 2021

Abstract
The refrigeration cycle of a reversible water-to-water heat pump has been investigated at different operation parameters of a laboratory installation. The investigation has been accomplished in cooling working conditions. The real operation cycles of the pump have been plotted in “logp-h” diagram by determination of definite thermodynamic parameters of the refrigerant. For this purpose, COOL PACK software has been used. The investigated refrigeration cycles are characterized by different switch off temperature of the heat pump. Based on the obtained results, the following parameters characterizing the heat pump’s efficiency have been determined: specific heat of vaporization, specific compression work, specific heat of condensation, and coefficient of performance.
Methodology for assessing the residual resource during the operation of high-temperature units
Authors: Nikiforov A , Prikhodko E , Kinzhibekova A , Karmanov A 
Published: January 2021

Abstract
The article analyses the main methods for determining the residual resource of these aggregates. Considering the imperfection of the above methods for estimating the residual resource, a method was developed for determining the residual resource of the linings of high-temperature units. The main parameters, which influence the residual resource of the lining, were determined during the operation of the units. In order to take into consideration the influence of temperature stresses on the residual resource of the sintering furnace, we examined a schedule for heating the furnace after an overhaul and calculated the temperature stresses that occur during heating and compared them with the acceptable values. Considering the temperature of the working medium, which exceeded the calculated one – was made according to the records of the operation logs. In general, the obtained result reflects a picture of the actual operation of the sintering furnace between its repairs. For its implementation into real operation, it is necessary to combine a number of measuring processes into a single information complex: a continuous measurement of the lining temperatures during heating; a burner performance (from the position of the torch profile and fuel oil spills); the quality of the resulting technological cakes, etc.
Modeling the influence of the characteristics of renewable organic materials on the energy performance of the boiler
Authors: Nikiforov A , Prikhodko E , Kinzhibekova A , Nurkina Sh 
Published: January 2021

Abstract
The object of the modeling is the process of burning organic waste, depending on the nature of the origin of the fuel, its chemical and fractional composition, density and lower calorific value. Processing the results of experimental study using analysis of variance will allow to estimate the variance caused by each factor individually and determine the level of influence of the factors on the output parameters of the process. It is necessary to obtain not only the form of this dependence, relying on the experimental data, but also to assess the influence of each factor on the lower calorific value. The analysis of the obtained dependence shows that the airflow speed and the fractional composition of this fuel have the greatest influence on the efficiency of the boiler plant. Checking the significance of the coefficients showed that all the coefficients of this model are significant. The regression dependencies were obtained that estimate the lower calorific value and the efficiency of the boiler which burns briquettes from organic matter; the analysis of the obtained dependencies was carried out, the significance of the coefficients included in the model was checked; the composition factor has the greatest influence on the lower calorific value.
Modeling the basis power in the systems for continuous transport of fluids and bulk materials
Authors: Dinolov O , Ilieva K 
Published: January 2021

Abstract
This paper presents a novel developed model for calculating the totally useful power in the systems for continuous transport of fluids and bulk cargoes, allowing deeper and more functional analysis of the energy efficiency of this systems by physically based decomposition of the electricity consumption of a useful and unhelpful ingredient. The model consists of nine mathematical expressions by which, after determining the type of system, the physically required minimum possible power consumption can be calculated and compared with the total consumption. A pumping system for the transport of condensate water from a deaerator to the drum of a steam generator of a thermal power plant has been selected as the subject of the model demonstration experiment. In the investigation carried out, the basis power of the pumping system was 606.6 kW and the total losses were about 302 kW. Other energy efficiency indices have also been identified. The researches should be continued in the direction of algorithmization of the model and its justification mainly for the Type II systems.
Development of innovative methods of thermal waste processing in modular waste burners with a high degree capture of harmful emissions
Authors: Orumbayev R K , Kibarin A A , Iliev I K , Torgayev A A , Kumargazina M B 
Published: January 2021

Abstract
Innovative methods have been developed for the thermal processing of solid waste in modular waste incineration plants with mechanical furnaces of boilers from 1.16 MW with gas afterburning over the layer and with a high degree of capture of harmful emissions in compact emulsifiers and activated carbon filters.
Wind energy assessment for low complex terrain using reference meteorological mast
Authors: Terziev A K , Panteleev Y , Ivanov M 
Published: January 2021

Abstract
The wind flow distribution over semi-complex terrains is evaluated by the roughness factor of the topography and the terrain peculiarities. The energy yield from the turbines in the park is based on the wind parameters extrapolated from the on-site measurement point to wind turbine hug height. For the lower zones of the terrain, the wind shear is influenced by the boundary layer, which can hardly be modeled using only tall tower data and a linear numerical model. The implementation of a second mast (reference), however, gives enough reliable data about the wind parameters at the lower part of the location and is used to adjust the flow and directional behavior from the main mast. The current study shows that for the low complex terrains using the proposed methodology an improvement of the assessed energy yield from the farm with 3% might be anticipated. Furthermore, for more complex terrains where the effect of the orography on the wind shear is more significant the expected improvement should be higher.
Estimation of wind speed and energy potential by atmospheric model for day-ahead market and wind power plants in Turkey
Authors: Devrim M A , Sakalli A 
Published: January 2021

Abstract
The requirement for energy has expanded day by day due to excessive consumption, developing technology, and population growth, especially after the Industrial Revolution. Since the investments for promoting renewable energy sources, The Turkish energy sector has been progressing in the way of renewable energy. This inevitable change in the energy sector and variable power generation values in wind energy directly affect the energy markets. Accompanying with the structural transformation of the energy sector, Turkey had launched the Day-Ahead electricity marketing system in December 2011. The price per megawatt-hour is determined on the open market by the supply and demand. Hatay province was selected in this study because of its highest wind potential. Temperature and wind speed values, observed in Hatay Samandağı for October 2019, were determined. The data was configured with The Weather Research and Forecasting Model. The results indicate that the wind speed at high altitudes could reach above 7 meters per second on Turkey’s eastern Mediterranean coast, Hatay. The results were compared with the real-time data, and the error rates were determined. In the selected region, the electrical energy values generated using the model results were calculated the day before.
Utilization of the energy potential of waste meal and creating of “green” workplaces
Authors: Mladenov M K , Yaneva S A 
Published: January 2021

Abstract
The issue of finding a suitable eco-technological approach for the utilization of waste meals generated in the production of vegetable oil is extremely relevant in terms of achieving a high “non-waste” degree in modern oil production. In practice, the direction related to the application of the meal as a material resource in animal husbandry is widely known – mainly for feeding of farm animals. At the same time, there are alternative areas related to other economic sectors, such as composting, biodiesel production, heat treatment and others, whose economic efficiency is still not sufficiently substantiated. Along with the topic of waste recovery, the measures for prevention of workers and ensuring safe and healthy working conditions are considered. The creation of “green” jobs, which directly or indirectly contribute significantly to the protection and restoration of the environment and to the reduction of the consumption of energy and raw materials, is extremely relevant in this direction.
Change point detection in recent hydropower generation in Romania
Authors: Neagoe A , Tică E-I , Popa F , Popa B 
Published: January 2021

Abstract
In Romania, about thirty percent of the installed capacity in National Power Grid and a third of the electricity generation is in hydropower plants. Thus, any aspect related to this form of renewable energy source is very valuable. Chronological records of yearly hydropower generation in Romania represent a time series that can be statistically analysed. The aim of this work is to determine the trend of this time series and, also, to locate the change points, where the time series has significant change. The period analysed is from 1980 to the present. To determine the change point of this time series, the Pettitt method was applied.
Plexiglass glove box for organic solar cells
Authors: Szolga L A , Stan C A 
Published: January 2021

Abstract
The term Glove Box probably creates an image of a glass box with black gloves, but Glove Boxes are as varied as the applications in which they are used. It is a hermetically sealed, watertight box, built for the purpose of sensitive applications. In this paper we present the design, the implementation and the testing of a Glove Box using plexiglass of 6mm thickness. The entire control of the system is flashed on an ATmega328 microcontroller. The sensors inside the box include oxygen sensor, gas sensor, humidity and temperature sensor. The plexiglass used provides robustness for the system but being lightweight it can be easily moved in different places in a research laboratory, compared with the steel Glove Boxes which are difficult to handle. The Glove Box was tested, by filling it up with Argon (inert gas) and introducing bulk heterojunction organic solar cells (BHJ OSC) and leaving them inside for 12hours. The measurement of the OSCs after 12h revealed that their efficiency decreased with only 20% compared to those left outside of the Glove Box which had an efficiency decrease of more than 70% from their initial value.
Robotic arm controlled by Android app through Bluetooth connection for organic solarcell manipulation
Authors: Szolga L A , Flueras G 
Published: January 2021

Abstract
In this paper we present the design of a three joint robotic arm printed out in polyethylene terephthalate glycol material which provide durability and has good chemical resistance. To move the arm, we used four servomotors for a complex orientation in horizontal and vertical plane. At the tip of the robotic arm a 5V vacuum pump was mounted to handle organic solar cells printed out on indium tin oxide treated glass sheets with a dimension of 25/24/1mm. For an easy and precise control of the robotic arm an Android application was developed with an intuitive user-friendly interface. The communication between the robotic arm and the Android App is established through Bluetooth protocol. The control of the robotic arm is executed by a custom program on an ATmega328 microcontroller.
High-level model based calibration technique design for SAR ADC
Authors: Skripnichenko M N 
Published: January 2021

Abstract
This article presents a method of developing and debugging algorithms for mixed-signal schemes using mathematical model. SAR ADC is used as an example to present the method. A divided capacitor array with is used in the mathematical model. The Laplase transform is used to replace differential integral equations with algebraic ones. The input dependence of the comparator on the switches in the capacitor array is the basis of the mathematical model. There are two additional models – capacitance mismatch model, which was performed by randomly adding the value of the uniform distribution from -0.01 to 0.01 unit of the smallest capacitance, and noise model, which was performed as randomly changing comparator offset. As a result, there is a mathematical model of SAR ADC with event-driven architecture. Switching of K0 sample switch and bit switches leads to changing of circuit state. Mismatch in the capacitor array during chip manufacturing leads to deterioration of key characteristics of ADC – signal-to-noise ratio and spurious-free dynamic range. There is an algorithm, that can calculate the capacitors mismatch and correct the output code. Such an algorithm shows the efficiency under the conditions of capacitor mismatch and comparator input noise. With this algorithm, the signal-to-noise ratio has been increased by 7.3 dB, which is equivalent to 1.2 bit ENOB. The spurious-free dynamic range has been increased by 16.8 dB. Using the mathematical model when designing and debugging calibration algorithms speeds up these processes.
Information management and monitoring system for a grapes harvesting robot
Authors: Tziridis K , Nikolaou A , Kalampokas T , Vrochidou E , Pachidis T , Papakostas G A , Kaburlasos V G 
Published: January 2021

Abstract
In recent years, there has been an increasing integration of high technology in the execution of agricultural tasks towards improving the quality of the produced products, while reducing production costs. In this context, there is a special interest in the development of automatic agricultural robots (Agrobots) with advanced techniques of collecting, processing data, decision making and applying actions. A key element of the successful integration of such autonomous robots is the information management and monitoring system (IM2S) that accompanies it. This work presents the IM2S developed for an autonomous grapes harvesting robot, as part of a national project. Details regarding the system’s design are presented, covering system requirements, functional specifications, Graphical User Interface (GUI) design, database design and system-robot communication. Along with the presentation of the IM2S design, the special functional and technological requirements that must be met, are also discussed. Thus, the system could be a useful tool for the human operator. Moreover, the designed system can be easily adapted to collaborate with any robot meeting specific communication requirements. This makes the proposed IM2S a universal tool for any grape harvesting Agrobot already deploy or will be developed in the future.
Kinematic model of a cow milking manipulator with simultaneous positioning at four given points
Authors: Ruzin S S , Shilin D V , Dorokhov A S , Pavkin D Yu , Chepurina E L 
Published: January 2021

Abstract
During the study, the authors have solved the problems associated with the kinematics of a manipulator intended for the automatic care of cattle. The working unit of the manipulator is a system positioning all four milking cups in the individual location of the udder teats. A significant advantage of this manipulator kinematics is the ability to simultaneously connect milking cups to the teats of a cow’s udder to provide physiologically more correct milking and reduce the total milking time.
A review on the methods for big data analysis in agriculture
Authors: Evstatiev B I , Gabrovska-Evstatieva K G 
Published: January 2021

Abstract
The integration of information and communication technologies into agriculture lead to the development of precision agriculture. Nowadays it relies on Internet of Things devices, geospatial data, historical and real-time information, which has the potential to transform farming into smart farming. However the use of Big Data requires significantly different skills and knowledge, compared to what many farmers and agronomists possess, which is an obstacle for their effective use. This study aims to summarize and provide insight into the common methods used for data analysis in a wide variety of agricultural applications. Initially, the basic characteristics and sources of agricultural data are explained. Next, a review of the common data analysis methods (classification, clustering and regressions) is provided, containing information about the data sources used as well as the desired goal of the analysis. At the end of the paper, a summary is given on the applicability of data analysis methods depending on the desired goals.
Effect of Si element on the interfacial reaction of Ti3SiC2 reinforced Al matrix aomposites
Authors: Zhang Jianbo , Jin Yiming , Man Xucun , Zeng Hao , Liu Jinping , Zhang Xuehui 
Published: January 2021

Abstract
The interfacial reaction behavior of Ti3SiC2/Al andTi3SiC2/Al-10si matrix composites at high temperature was studied by XRD and SEM. The results showed that the reaction between Ti3SiC2 and Al matrix is

Ti

3

SiC

2

+
Al
→
TiCx
+
Si
+

Al

3

Ti
.

Ti3SiC2 particles in the Ti3SiC2/Al composite were almost completely reacted after 700 °C/1 h treatment, whilea large amount of Ti3SiC2 particles still existed in the Ti3SiC2/Al-10Si composite under the same treatment condition. In addition, the friction coefficient and wear amount of Ti3SiC2/Al composite were 0.54 and 0.167 g, respectively, and that in Ti3SiC2/Al-10Simatrix composites were 0.29 and 0.019 g. According to the critical condition of ΔG = 0, it is calculated that when the activity of Si is greater than 0.57, the interfacial reaction between Ti3SiC2 and Al matrix is inhibited.
ZnO as an anti-reflective layer for GaAs based heterojunction solar cell
Authors: Jin Xin , Tang Naiyun 
Published: January 2021

Abstract
Currently, how to improve the efficiency of solar cells has attracted wide attention. ZnO film is one of the most effective films today, which can act as both emitter and anti-reflective coating of solar cells. In this paper, n-type ZnO/p-type GaAs solar cell is modeled by analyzing the band edge discontinuities, electric field distributions at the ZnO/GaAs interface and cell parameters with varying ZnO layer thickness, affinity values and carrier concentration. Moreover, in order to improve the band offset alignment at the heterojunction, Mg doped ZnO emitter is a possible alternative. Then, the thickness and carrier concentration of MgZnO emitter layer are studied and simulation results show stronger electric field, better fill factor and higher efficiency. After optimization of two solar cells by using Silvaco Atlas, it is observed that the conversion efficiencies of ZnO/GaAs and MgZnO/GaAs solar cells are 22.84% and 23.44% respectively.