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The research presents an experiment with a model of an electronic generator for energy injection into the plasma of a fusion reactor. By recording a non-ionizing field in the vicinity of a fusion reactor, it was determined that this field has an extremely high growth rate. At the site of the maximum intensity of the field of non-ionizing radiation, commercial surge arresters with a flexible model of surge arresters were used for experimentation. It has been found that the commercial surge arresters have an efficiency of about 20%. For the efficiency of the flexible model, it was found to be slightly less than 40% (and to be achieved by the application of alpha particle radiation). Since neither of these efficiencies guarantee reliable operation of the gas-filled surge arrester, it was concluded that essential electronics in the vicinity of the fusion generator must be protected. However, since this protection can only be implemented in a fusion reactor, the fact remains that the environment of such a reactor is extremely contaminated with non-ionizing radiation. Commercial surge voltages are isolated for testing since the protection of electronic circuits from fast overvoltages is a critical point for the functioning of modern electronics.

The perforated plates are commonly used for gas flow control in the wide-angle diffusers of electrostatic precipitators of large power plants. Many studies dealt with the investigation of the effects of the perforated plate?s geometry on flow parameters in the cases where incoming flow is perpendicular to the plate and the plate is covering the whole cross-section of the flowing channel. These results are partially applicable in cases where flow is inclined on the plate or when the plate is not occupying the whole cross-section of the channel. The subject of this work is a numerical investigation of flow through the rectangular channel with a perforated plate in various positions in the cross-section of the channel. The aim was to investigate the effect of the plate position on the flow. The perforated plates were modeled as thin porous media of finite thickness by using the directional loss model. Numerical experiments are carried out by using Computational Fluid Dynamics software Ansys CFX. Results of pressure drop and velocity distribution behind the plate are compared to the results of CFD simulation of the full 3D plate model. In order to obtain a reasonable agreement both of the pressure drop and velocity distribution behind the plate when using a simplified thin porous plate model, the value of streamwise permeability of the plate had to be adjusted. The level of adjustments has determined iteratively and it depends on the plate position in the channel?s cross-section.

The European initiatives for citizens? inclusion in the air quality monitoring process have impacted the participants? knowledge, and attitudes towards air pollution and have led to a higher sense of community toward activities and measures against air pollution. In the Republic of Serbia, an experiment with self-made sensor kits "Klimerko - Air to the Citizens" started in 2018. In this paper, we have presented the level of agreement of the PM readings from selected Klimerko devices to the PM readings of the reference equivalent PM monitors from the National Air Quality Monitoring Network in the cities of Bor and Belgrade. The Klimerko devices that we tested showed excellent stability and reliability during the comparison period. The conclusion of our investigation is that the properly calibrated Klimerko devices could be applied for indicative measurements of PM mass concentrations in the ambient air.

Homogeneity of the flue gas flow through the chamber of an electrostatic precipitator is one of the basic influencing parameter on dedusting efficiency. This paper presents results of a multiobjective optimization study of the flue gas controlling devices of electrostatic precipitator of 324 MWe lignite fired unit A4 of Thermal Power Plant "Nikola Tesla" in Serbia. The aim was to achieve better flow homogeneity in the cross-section of the precipitator compared to the original design. Additional constraints were to maintain the minimum as possible overall weight of the proposed design as well as pressure drop through the precipitator. Numerical simulations based on Computational Fluid Dynamics were used to investigate dependence of the velocity distribution in the ducts and precipitator?s chamber with respect to the geometrical parameters of tested concepts of turning blades. A series of 22 detailed full-scale numerical models of the precipitator with different concepts of turning vanes designs were developed. Assessment of the flow field uniformity for each tested design was performed based on the analysis of several homogeneity parameters calculated for selected vertical cross-sections of the precipitator. After the reconstruction according to optimized design, results of measurements confirmed significant improvements of the velocity distribution in the vertical cross-sections of the precipitator, increase of dedusting efficiency and reduction of PM emission.

A novel statistical model based on a two-layer, contact and information, graph is suggested in order to study the influence of disease prevalence on voluntary general population vaccination during the COVID-19 outbreak. Details about the structure and number of susceptible, infectious, and recovered/vaccinated individuals from the contact layer are simultaneously transferred to the information layer. The ever-growing wealth of information that is becoming available about the COVID virus was modelled at each individual level by a simplified proxy predictor of the amount of disease spread. Each informed individual, a node in a heterogeneous graph, makes a decision about vaccination “motivated” by their benefit. The obtained results showed that disease information type, global or local, has a significant impact on an individual vaccination decision. A number of different scenarios were investigated. The scenarios showed that in the case of the stronger impact of globally broadcasted disease information, individuals tend to vaccinate in larger numbers at the same time when the infection has already spread within the population. If individuals make vaccination decisions based on locally available information, the vaccination rate is uniformly spread during infection outbreak duration. Prioritising elderly population vaccination leads to an increased number of infected cases and a higher reduction in mortality. The developed model accuracy allows the precise targeting of vaccination order depending on the individuals’ number of social contacts. Precisely targeted vaccination, combined with pre-existing immunity, and public health measures can limit the infection to isolated hotspots inside the population, as well as significantly delay and lower the infection peak.

Sustainable development indicators mainly provide information that can link the observed energy system with sustainable development. This paper considers building energy indicators in order to provide monitoring and measurement of energy performance of buildings. The results of measurement which are considered were obtained in school buildings in Serbia. The aim of this paper is to select, define, and calculate energy indicators as criteria for evaluating the quality of public buildings, with regard to sustainable development. The criteria for assessing sustainability are quantified by certain defined sets of economic, social and environmental indicators. The ASPID method of multi-criteria analysis is also described and mathematically presented. This method is based on the synthesis technique of fuzzy sets and the sustainability of the school buildings was based on their assessment as complex energy systems.

The electrostatic precipitator system of the lignite fired 350 MWe unit B1 of Thermal Power Plant Kostolac B has been modernized during 2014. The results of complex in site measurements, performed in the frame of performance control test at the beginning of the exploitation period of the upgraded electrostatic precipitator proved that, under normal and guarantee working conditions of the boiler and precipitator, the emission of particulate matter do not exceed limiting value. After the period of precipitator further adjustments, five series of measurements in the frame of acceptance test were performed in accordance with relevant standards. This paper presents results of the investigation of particulate matter concentration, laboratory analysis of the lignite, fly and bottom ash samples, working parameters of the unit and upgraded electrostatic precipitator as well as results of the calculations. The averaged mean particulate concentration at the exit of upgraded electrostatic precipitator of the unit B1 during Acceptance test was below guaranteed value. It is confirmed that adjustments of electrostatic precipitator electrical parameters have improved electrostatic precipitator efficiency, as well that electrostatic precipitator could work highly efficiently in energy save mode with lower power consumption. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III42010 Reduction of Air Pollution from Thermal Power Plants of the PE Electric Power Industry of Serbia and Grant no. TR33050]

Substantial knowledge is available on the association of the indoor school environment and its effect among schoolchildren. In the same context, the SINPHONIE (School indoor pollution and health: Observatory network in Europe) conducted a study to collect data and determine the distribution of several indoor air pollutants (IAPs), physical and thermal parameters and their association with eye, skin, upper-, lower respiratory and systemic disorder symptoms during the previous three months. Finally, data from 115 schools in 54 European cities from 23 countries were collected and included 5175 schoolchildren using a harmonized and standardized protocol. The association between exposures and the health outcomes were examined using logistic regression models on the environmental stressors assessed in classroom while adjusting for several confounding factors; a VOC (volatile organic compound) score defined as the sum of the number of pollutants to which the children were highly exposed (concentration > median of the distribution) in classroom was also introduced to evaluate the mul tiexposu re - outcome association. Schoolchildren while adjusting for several confounding factors. Schoolchildren exposed to above or equal median concentration of PM2.5, benzene, limonene, ozone and radon were at significantly higher odds of suffering from upper, lower airways, eye and systemic disorders. Increased odds were also observed for any symptom (sick school syndrome) among schoolchildren exposed to concentrations of limonene and ozone above median values. Furthermore, the risks for upper and lower airways and systemic disorders significantly increased with the VOCs score. Results also showed that increased ventilation rate was significantly associated with decreased odds of suffering from eye and skin disorders whereas similar association was observed between temperature and upper airways symptoms. The present study provides evidence that exposure to IAPs in schools is associated with various health problems in children. Further investigations are needed to confirm our findings. (C) 2020 Elsevier B.V. All rights reserved.

Oxy-fuel combustion is the most promising carbon capture and storage technology, which eliminates carbon dioxide emissions into the atmosphere and also decreases nitrogen oxides emissions thereby lowering global warming potential. In order to implement oxy-fuel combustion technology in full scale power plants, its costs, mainly connected with the amount of pure oxygen produced, must be lowered. The main hypothesis is that it is possible to maintain similar velocity and heat transfer distribution while maintaining stable and efficient burner operation during both combustion technologies modifying burner aerodynamics. Excess oxygen is chosen as a representative parameter of burner's performance and investigation is carried out for four different oxy-fuel burner oxygen excess ratios (λ: 0.8, 0.98, 1.07, and 1.24) together with reference air combustion case. This study suggests a workflow, based on semi-industrial experimental investigations and computational fluid dynamics model composed of advanced sub-models for different combustion phases for development of real scale dual-mode coal swirl burners able for efficient operation during both combustion regimes. The results show that the temperature in near-burner zone and nitrogen oxides emissions increase, while carbon monoxide emissions decrease with the increase of burner oxygen excess ratio, and stable combustion with similar velocity and temperature distributions for both combustion modes is achieved for oxygen excess ratio of 1.07, with decrease in nitrogen oxides and carbon monoxide emissions during oxy-fuel combustion. The performed study demonstrates that it is possible to choose the appropriate burner settings regarding nitrogen oxides and carbon monoxide emissions and burner's ability to operate stably in both air and oxy-fuel combustion modes. © 2019 Elsevier Ltd

Previous studies have shown that poorly ventilated classrooms can have negative impact on the health of children and school staff. In most cases, schools in Serbia are ventilated naturally. Considering their high occupancy, classroom air quality test determines the level of air pollution, after which it is possible to implement corrective measures. The research presented in this study was conducted in four schools which are located in different areas and have different architecture designs. Measurements in these schools have been performed during the winter (heating season) and spring (non-heating season) and the following results were presented: indoor air temperature, relative humidity and carbon dioxide concentration. These results show that the classroom average concentration of carbon dioxide often exceeds the value of 1500 ppm, during its full occupancy, which indicates inadequate ventilation. Measurement campaigns show that carbon dioxide concentration increased significantly from non-heating to heating season in three of the four schools. Analysis of measurements also determined high correlation between relative humidity and carbon dioxide concentration in all schools in winter season. This fact may constitute a solid basis for the fresh air supply strategy. [Projekat Ministarstva nauke Republike Srbije, br. III42008: SINPHONIE - Schools Indoor Pollution and Health: Observatory Network in Europe]

Respirable particulate matter present in outdoor and indoor environments is a health hazard. The particle concentrations can quickly change, with steep gradients on short temporal and spatial scales, and their chemical composition and physical properties vary considerably. Existing networks of aerosol particle measurements consist of limited number of monitoring stations, and mostly aim at assessment of compliance with air quality legislation regulating mass of particles of varying sizes. These networks can now be supplemented using small portable devices with low-cost sensors for assessment of particle mass that may provide higher temporal and spatial resolution if we understand the capabilities and characteristics of the data they provide. This paper overviews typical currently available devices and their characteristics. In addition it is presented original results of measurement and modelling in the aim of one low-cost PM monitor validation.

Indoor air quality (IAQ) is very important for children health and well-being, since children are particularly vulnerable and sensitive on presence of air pollutants. This study was performed in two naturally ventilated schools located in the same municipality. First school is located in urban area, at residential - industrial site, while the other school is situated in rural area. School buildings were chosen based on their urban environment features. The measurements were carried out in heating as well as in non-heating period in duration of five consecutive working days. The objective of the study was to analyze IAQ in the classrooms with special emphasis on levels and diurnal variations of particulate matter (PM10 and PM2.5), carbon dioxide (CO2) and nitrogen dioxide (NO2) in occupied and unoccupied school classrooms. In this paper, the CO2 concentrations were measured at both indoor and outdoor environments. Concentrations of CO2 higher than 1000 ppm were regularly detected in the classrooms during teaching hours. Indoor concentrations of PM10 were not exceeded the guideline, daily average, value of 50 μg/m3. Concentrations of PM2.5 were exceeded the guideline, daily average, value of 25 μg/m3 in both school during heating period. Concentrations NO2 were not exceeded the guideline value of 200 μg/m3. Ventilation rates were calculated and compared with the prescribed limits. In both occupied and unoccupied periods high correlation between CO2 and PM concentrations was determined. [Projekat Ministarstva nauke Republike Srbije, br. III42008]

This study investigated seasonal variation of PAHs and their partition between gas and particulate-bounded phases in indoor and outdoor air in 4 schools In Serbia located at different locations. The sampling campaigns were conducted during one workweek at each school successively. Campaigns were conducted in schools during heating and non-heating seasons in December 2011 and June 2012. Seasonal variations of gas and particle-bounded PAHs concentrations were observed with higher levels during heating season. The highest total PAH values were associated with the gas phase in both sampling periods. The total PAHs concentration at indoor and at the outdoor sites, during heating season, ranged from 88.45 to 447.72 ng/m(3) and 201.69 to 1017.15 ng/m(3), respectively. During non-heating season, the total PAHs concentration ranged from 36.91 to 271.57 ng/m(3) in Indoor environment and 27.00 to 132.32 ng/m(3) in outdoor environment. Most of the I/O ratios were less than 1, which indicated that the indoor PAHs were mostly from outdoor sources. The use of diagnostic ratio showed that traffic emission and coal combustion are the major sources of PAHs. Only the diagnostic ratios for the school located near the industrial area showed significant deviation compared to other schools. U ovom radu su istraživane sezonske promene PAH i njihova raspodela, u gasnoj fazi i respirabilnim česticama u vazduhu unutrašnjeg prostora i spoljašnje sredine u 4 škole u Srbiji koje se nalaze na različitim lokacijama. Kampanja uzorkovanja je sprovedena tokom jedne radne nedelje u toku grejnog i negrejnog perioda (od decembra 2011. do juna 2012.) u svakoj školi. Uočene su sezonske promene nivoa PAH u gasnoj fazi i česticama, sa višim koncentracijama tokom grejnog perioda. Izmerena je veća vrednost zbira ukupnih PAH tokom oba perioda u gasnoj fazi nego PAH u česticama. Ukupna koncentracija PAH tokom grejnog perioda u unutrašnjem prostoru se kretala u opsegu od 88,45 do 447,72 ng/m3, a u spoljašnjoj sredini od 201,69 do 1017,15 ng/m3. Tokom negrejnog perioda, ukupna koncentracija PAH-ova je bila 36,91-271,57 ng/m3 u unutrašnjem prostoru, dok je u spoljašnjoj sredini bila 27,00-132,32 ng/m3. Većina I/O odnosa je bila manja od 1, što ukazuje da PAH u unutrašnjem prostoru uglavnom potiču iz spoljašnjeg vazduha. Na osnovu dijagnostičkih odnosa zaključeno je da su saobraćaj i sagorevanje uglja glavni izvori PAH. Jedino dijagnostički odnosi za školu koja se nalazi u blizini industrijske zone pokazuju značajno odstupanje u poređenju sa drugim školama.

The indoor air quality in schools is very important for health and learning abilities of children. The primary indoor CO2 source in classrooms is the respiration of school building occupants. Also, CO2 comes from outside as a result of fossil fuels combustion. CO2 concentration depends on a ventilation rate, size of the classroom, number of occupants and their activity and time they spend in school building. Unfortunately, ventilation rates in schools were not often measured, even in cases when inadequate ventilation caused pupils health problems and their absence from school. The increase in indoor CO2 concentration above the outdoor concentration is considered as a good surrogate for the indoor concentrations of bio effluents. This paper presents the research of ventilation rates in five naturally ventilated schools in urban and rural areas in Serbia during the heating season. CO2 concentrations were measured outdoor and in three classrooms for five working days, continually. Ventilation rates are calculated based on measured concentrations of CO2. The results have shown that classrooms in Serbian schools have inadequate ventilation during the heating period. Mean value of carbon dioxide concentration has often been exceeding 1000 ppm. (C) 2014 Elsevier Ltd. All rights reserved.

The requirements of the international document Directive 2001/80/EC relating to limitation of the particulate matter emissions from large thermal power plants have been incorporated into relevant regulations of domestic legislation. In accordance with the commitments, since 2005 it was started with reconstruction and modernization of electrostatic precipitator system of all thermal units within the Electric Power Industry of Serbia. The reconstruction and modernization of electrostatic precipitator system of the unit B2 of thermal power plant 'Nikola Tesla B' was done during 2011, while the reconstruction of the electrostatic precipitator system of the unit B1 was conducted in 2012 year. One of the main objectives of performed reconstructions and modernizations, financed by donations of the European Union, was to decrease the emission of particulate matter in the flue gas from these units down to level below 50 mg/Nm3, in normal conditions and under guaranteed operating conditions of the boiler and electrostatic precipitator system. This paper presents results of the measurements of particulate matter concentration performed in accordance with standards ISO 9096 and EN 13284-1, immediately after the reconstruction and shortly before the end of the period of about 1 year after the reconstruction, as a part of control and guarantee investigations of the reconstructed electrostatic precipitators of Thermal Power Plant Nikola Tesla B units. In addition, this paper presents re sults of labosatory analysis of the coal samples taken during test, working parameters of the unit and upgraded electrostatic precipitator system during the tests as well as results of the calculations. The results of the measurements confirm that particulate matter concentration in the flue gas from reconstructed electrostatic precipitators fall down below guaranteed values, thus confirming the effectiveness of the reconstructive operations.

Indicative air quality and environmental parameters data with high temporal and spatial resolution including online resource of near real-time and historical data need to be available for citizens. Currently inexpensive air quality sensors have been developed and embedded in small monitoring platforms whose characteristic have been evaluated. This paper shows first results of an evaluation of the performance characteristics of DNET designed low-cost platform under field conditions. They were collocated next to an air monitoring station (AMS) in Belgrade which was a part of the State Air Quality Monitoring Network. Used platforms consisted of electrochemical and infrared sensors for the gaseous pollutants NO2, NO, O3, CO, CO2, and optical devices for PM0.5-2.5 and PM2.5-10 as well as sensors for monitoring T, p and RH. During the three campaigns (Feb-Mar and Oct-Nov 2014), each in duration of 10-15 days, 13 platforms equipped with the same type of Alphasense sensors for gases and DYLOS (USA) monitor for PMs, were tested. The AMS for the first campaign was next to a street with low/medium traffic, while the AMS for the second and last campaign was near the intersection of roads with medium to intense traffic activity. Pilot DNET platforms may be also used for indicative levels of PM2.5, PM10, CO and CO2. The used low-cost devices need to be improved with sensors that will eliminate the influence of O3. The necessity for improving the methodology of calibration of low-cost devices in the field was identified.

The quality of indoor school air is very important for health and learning performance of children and teachers. The primary indoor CO2 source in classrooms is the respiration of school building occupants. Also, CO2 comes from outside as a result of fossil fuels combustion. CO2 concentration depends on a ventilation rate, size of the classroom and number of occupants and time they spend in school building. Unfortunately, ventilation rate in schools was not measured very often, even in cases when inadequate ventilation caused health problems and the absence of pupils from school. Carbon dioxide concentration is used as a surrogate of the outdoor supply air rate per occupant instead of expensive and potentially complicated measurements. In this paper, the CO2 concentration measurements at the indoor and outdoor environment were performed in five schools in urban and rural areas in Serbia during heating season. Ventilation rates were calculated and presented in comparison with current regulations.

Background: Numerous epidemiological studies have associated exposure to PM in the outdoor environment to adverse health effects. Nowadays, the attention is paid to indoor air pollution, since peop...