Modelling Energy Consumption of the Republic of Serbia using Linear Regression and Artificial Neural Network Technique

The objectives of the study are twofold. First, we aim to examine the most influential socio-economic indicators to explain energy consumption in Republic of Serbia. The second objective is to develop models that are able to predict the future energy consumption in the Republic of Serbia. This could be the first important step towards proper energy management in the country. Several potential socio-economic indicators are selected to be the independent variables. Regression analysis is conducted to select the most relevant independent variables as well as building the multiple linear regression (MLR) models. In addition, an artificial neural networks (ANN) model is developed as a comparison. Finally, the energy demand is projected to the year 2022. It is found that both models show the declining trend with respect to the current level of energy consumption

Reliability of Different Environmental Noise Monitoring Programs in Serbia

Annual environmental noise monitoring is a legal requirement for local self-governments in the Republic of Serbia. However, Serbian legislation does not stipulate specific monitoring procedures, so each local self-government unit has to create its own environmental monitoring program within its jurisdiction. This paper analyzes the reliability of noise monitoring programs in local self-government units, based on short-term measurements. The reliability of applicable environmental noise monitoring programs in Serbia was examined by simulating the program imlementation to the results of noise monitoring obtained through continuous measurement over a period of one year. The above mentioned simulation showed that the monitoring programs based on short-term monthly measurements and a measurement time interval over 24 hours have the best repeatability and reliability result, especially at locations with the same daily noise profile and the occasional occurrence of unexpected short-term noise events. The results obtained in this study indicated that, either with higher or lower degrees of reliability, other programs can be used to monitor noise at measurement points near major urban roads with heavy and relatively constant vehicle flow throughout the day

Approximation of Electric Field in Biological Tissue

This paper presents the method of homogenization of several different biological tissues in order to simplify the numerical calculation of the electric field distribution in certain biological structures of interest. For this purpose, a 3D model was used with blocks that have the same electromagnetic characteristics as their corresponding biological tissues of the human head. The results obtained in the case of homogenized block model were compared with the ones obtained by using the original heterogeneous model containing the following tissues: skin, fat, muscle, bone, and brain. Homogenization of the model has been caried out only for the layers that precede the layer in which the analysis of electric field distribution was performed. A smart phone was used as the source of electromagnetic radiation at a frequency of 0,9 GHz. A comparative analysis of the electric field intensity in the layer of interest indicates good matches for the heterogeneous and homogenized models. Based on the obtained results, deviations in the electric field intensity can be observed for both models. These deviations range from 3,7% to 5,2% for different layer thicknesses.The proposed homogenization method significantly simplifies the modelling and also reduces the simulation time required to obtain appropriate results

Simulation of fire spread between residential buildings regarding safe separation distance

Određivanjem optimalne sigurne udaljenosti između zgrada bave se mnoge sigurnosne i ekonomske analize. Općenito je poznato da se povećanjem razmaka povećava zaštita od širenja vatre na susjednu zgradu, ali se smanjuje isplativost urbanih rješenja. Iz tog se razloga u ovom radu koristi programski paket CFD Large Eddy Simulation method of Fire Dynamics Simulator kako bi se odredila optimalna udaljenost potrebna da bi se spriječilo širenje vatre izmđu dviju stambenih grada okrenutih jedne drugoj. Analizirali su se minimalni uvjeti potrebni da bi se zapalile zavjese na prozorima zgrade izložene vatri smještenoj na raznim udaljenostima (3,5 m, 4,0 m i 4,5 m). Dobiveni rezultati pokazuju da se na udaljenosti od 4,5 m vatra ne širi i da je ulazna količina topline na površini zavjese veća od vrijednosti kritične količine topline od 12,6 kW/m2 prihvaćene u mnogim graditeljskim kodeksima.Determination of optimal safe distance between buildings is a task of many safety and economic analyses. Generally, it is known that increasing separation distance increases fire protection of an adjacent building, but decreases the cost effectiveness of urban solutions. For this reason, CFD Large Eddy Simulation method of Fire Dynamics Simulator software package has been used in this paper to determine optimal separation distance required for preventing fire spread between two residential buildings facing each other. The minimum conditions necessary for ignition of the window curtains in the fire-exposed building located at different building distances (3,5 m, 4,0 m and 4,5 m) were analysed. The obtained results show that the fire does not spread at the distance of 4,5 m, and that the incident heat flux at the curtain surface is higher than the critical heat flux value of 12,6 kW/m2 adopted in many building codes

EMMISION OF POLLUTANTS ORIGINATING FROM MOBILE SOURCES ON THE EXAMPLE OF THE CITY OF KRAGUJEVAC

Traffic jam makes cities less pleasant for living and it also decreases traffic efficiency whereas travel time, fuel consumption and drivers’ stress are increased. A special problem is its influence on people’s health caused by emission of exhaust gases. Emission of pollutants originating from mobile sources is primarily conditioned by a level of technologies applied to the vehicle, vehicle’s technical state, traffic intensity, traffic density, local climate conditions, etc. Air pollution due to use of motor vehicles is becoming one of the major problems in urban areas across the world. With the increase of the number of motor vehicles and traffic intensification, the influence of exhaust gases on human environment also has increased. Considering the average age of the vehicles participating in traffic in the city of Kragujevac and the traffic capacity of traffic arteries, most frequently not designed for such a large number of vehicles concentrated at the core of the city, it is to be expected that the air pollution coming from mobile sources will become a problem that requires detailed analysis. For that purpose, a detailed statistical analysis of the vehicle fleet of the city of Kragujevac is conducted. An estimation of the influence of the vehicles on the air pollution in the city of Kragujevac, has been given in the paper

REDUCTION OF MOTOR VEHICLES EMISSION BY USING NATURAL GAS AS AN ENERGY SOURCE

As the automotive industry perceived negative effects of road transportation to the environment, it has intensively worked on new technological solutions during several decades, with the goal of reducing the negative effect of vehicles to the environment. That is why priorities of contemporary and future development of vehicles, engines and accompanying equipment are the following: reduction of fuel consumption and reduction of emission of exhaust gases. One of the ways to solve current tasks of the automotive industry is the use of alternative fuels, that is, alternative energy potentials. This paper analyzes natural gas as alternative fuel for motor vehicles. After description of basic physical and chemical properties and the analysis of use of natural gas as a fuel for ICE, this paper presents reduction of motor vehicles emission by using natural gas as a fuel

BELT CONVEYOR DRIVE GEARBOX PROBLEM CAUSED BY UNPAIRED GEARS- A CASE STUDY

Abstract: Belt conveyors for all kinds of materials are very important piece of equipment in mining and excavation industries. This paper is presenting a case study of belt conveyor driving unit vibration analysis. The analyzed belt conveyor is operating in cooper production plant and it is conveying cooper ore from mining site to process plant. In order to detect the possible defects on belt conveyor drive units, vibration measurements are conducted on all four drive units. Measurement points are set on bearing housings of electric motor and gearbox as defined by ISO 10816-1.   Key words: gearbox vibration analysis, gear tooth wear, unpaired gears, shaft misalignmen

ACCIDENT PREVENTION IN SEVESO FACILITIES: EXAMPLE OF THE COPPER FLOTATION PLANT IN BOR

In the near future, sustainable development of mining will inevitably be included in the raising of ecological awareness. When Serbia joins the EU, the mining industry will have to abide by European ecological standards and legislation, with which it is currently in the process of harmonization. This will primarily protect the population living in mining areas from large-scale accidents, as well as from the existing pollution sources. Pollution of the town of Bor began more than a century ago when industrialist Đorđe Vajfert was granted the excavation concession, as he hoped he would find gold there. Instead, he found copper, which was first extracted by the French. Since then, the development and survival of the town have depended on copper mining, which necessarily degraded the environment. For the purpose of harmonizing the environmental legal regulation of current copper production and, above all, reducing the risk of large-scale accidents, the Centre for Occupational and Environmental Risk Management of the Faculty of Occupational Safety in Niš has prepared the Report on the Safety of Flotation Plant Bor at the request of Copper Mine Bor, a subsidy of RTB Bor (Mining and Smelting Complex Bor). The Report is essentially a study defining the operation objectives and principles of Seveso facility operators for risk control against chemical accidents. The purpose of this study was to improve the implementation of accident prevention principles at the Flotation Plant Bor. This paper presents the parts of the study that pertain to prescribed preventive procedures and measures against accidents due to hazardous materials that are present during flotation. It covers the following aspects: facilities; equipment; piping; machinery; tools; repositories; flotation tailings pond; analysis and assessment of the effectiveness of the system of occupational safety and fire and explosion safety; assessment of impact on employees, the surrounding population, and buildings, and the possible harmful environmental impact; assessment of unwanted event incidence; and calculations of vulnerable zones

NUMERICAL STATIC ANALYSES OF PANEL AIR FILTER PROTOTYPE

Abstract. The Laboratory for air quality control at the Faculty of Occupational Safety in Niš in cooperation with several companies designed and produced prototypes of industrial panel dust filters as well as prototypes of charcoal cartridge filters. In order to obtain comprehensive and valid research results the authors carried out a number of field tests as well as numerical simulations and analyses of operating parameters and characteristics of several air purifier prototypes on original experimental setup. The aim of this paper is to present simulation results of static (stress and strain, including thermal effect) analyses of industrial air filter prototype. Simulation and visualization of results was done by means of SW SimulationXpress and SW simulation design study modules from Solid Works software package

APPLICATION OF TIME-SERIES METHODS FOR THE MODELING OF SUNSHINE DURATION SEQUENCES

This paper presents the application of statistical methods to determine the length of solar radiation based on the data obtained from the   meteorological station Negotin, and we may presume that these data are also representative for a wider area of northeastern Serbia. Negotin is a town in northeastern Serbia, in the Bor District, with the population of ca. 17000, near the border with Romania and Bulgaria. The results of the application of statistical methods allow us to predict the future trend of the time series, i.e. to predict the sunshine duration in the sample area. We performed the measurements using several models to predict the trend of the time series of sunshine duration, whereby it was essential to use the most suitable model. Selection and evaluation of models were applied to a series of annual sums of sunshine duration observed between 1991 and 2011 in the meteorological station in Negotin. Using an ARIMA model and the trends method, we obtained the predictions of sunshine duration in Negotin up to 2015. The prediction results show reduced sunshine duration on annual basis over the  observed time of prediction