Slavica Prvulovic

• University of Novi Sad

This paper aims to enhance the efficiency of biogas plants for the production of electrical and thermal energy by optimizing substrate selection and digester heating techniques. The study presents a comprehensive project of a biogas plant, including all necessary installations and a detailed methodology for equipment selection. Specific substrates...

This study examines the impact of cutting regimes on determining cutting resistance in the processing of polypropylene (PP) using the CNC lathe EMCO F5. The rationale for this research stems from polypropylene's rarity among thermoplastics in possessing structural stability, allowing for its comparison to metals and practical application in product...

This study investigated the solar power potential and performance in Serbia, a country with favorable solar conditions but limited resource utilization. The principal objectives of the investigation were to analyze the performance ratio (PR) and assess the electricity production of simulated solar power plants in different distribution areas. The P...

This study investigates the relationship between machine learning (ML) and marketing strategies, highlighting its transformative potential for businesses and governments. Machine learning enables sophisticated customer segmentation, predictive analytics, and personalization, all of which lead to more refined and effective marketing strategies. The...

This study focuses on the level of vibrations in technical systems, risk models, and the reduction of both vibrations and associated risks. The research subject includes hydropower plant facilities, which are strategically significant for the power industry, hold substantial investment value, and consequently are crucial for the state. Vibration di...

In this paper we are studying the problems of oil manufasturing and methods for solving them on the oil field in Amal. Problems on the oil field in Amal are: deposition of paraffin, occurrence of stratified sand, inefficient operation of the gas-lift system, salt deposition, inefficient oil desalination, and environmental problems. Without taking a...

The paper describes an analysis of the temperature drop and heat losses of crude oil along the l = 91000 m main oil pipeline. The analysis was performed for domestic paraffin oil with an average paraffin content of 15% and a pour point of 26 oC, when the initial heating temperature is t1 = 40 oC. Such oils have high flow temperatures and unfavorabl...

This work presents Combined Heat and Power (CHP) gas engine factory as one of the possible solutions for cogeneration in the industry which has high values of electrical and total efficiency, and the electrical efficiency relatively changes little with the change in power of the plant. The cost‐effectiveness of such a plant is significant to the su...

The paper presents a procedure for determining the optimal amount of thermal energy for the profitable operation of a biogas plant. The temperature at which anaerobic fermentation takes place shortens the time of fermentation and biogas production, but also the provision of higher temperatures requires a certain amount of thermal energy, whose cons...

The folowing article considers the process of determining the working temperature of the workpiece in the cutting zone when machining the machine plastic on the lathe. Maintenance of the processing temperature of the workpiece in the limits of less than 100 °C is possible with the application and programming of the fuzzy logic controller (FLC) for...

Paraffins and paraffin waxes are chemically stable. For that reason, for many types of oil, the treatment of high-paraffinic oils is conducted with the addition of modifiers of rheological properties. The flow properties of high paraffin oils are affected by the number and shape of formed paraffin crystals. The process of modifying of rheological p...

The paper presents the results of experimental research and simulation of the parameters of crude oil transport of pipes. The content of paraffin in oil has a dominant influence on the properties of paraffin oil, and in particular has an impact on the reduction of the flow properties of the oil. Oil heating improves the flow properties, reduces the...

In this paper the analysis and description of the operation of the Premix station for dosing the substrate into existing digesters whose location is in the system of the device for processing of liquid waste are described. Apart from the capacity and other entry parameters, the necessary diameter of the pipeline with the length of the section for s...

Three-phase controlled rectifiers have a wide range of applications, from small rectifiers to large. They are used for electro-chemical process, many kinds of motor drives, traction equipment, controlled power supplies, and many other applications. A simple analytic method of calculating higher harmonics of current generated by a three phase bridge...

The paper presents results of experimental research and simulation of the main parameters of crude oil pipeline transport. In Serbia, 70 % of the produced oil belongs to a paraffin type, of which over 25 % has a high content of paraffin. High-content paraffin oil usually has a high pour point. The paraffin content in crude oil from Vojvodina, Serbi...

The paper presents and describes in detail the specific procedures that are carried out during the repair of the crawler unit on the belt wagon BRs 1200.29/32, whose performance is the basis for high quality and efficient maintenance of these machines on site, as well as in repair shops. These procedures are complex interventions performed as part...

The paper gives an example of a biogas plant used for electricity and heat production. First, the role and importance of the biogas plant is presented, then an overview of the raw materials used for biogas production is given, a project of the biogas plant with constituent elements is given, as well as a description of the technological process and...

Three-phase controlled rectifiers have a wide range of applications, from small rectifiers to large. They are used for electro-chemical process, many kinds of motor drives, traction equipment, controlled power supplies, and many other applications. A simple analytic method of calculating higher harmonics of current generated by a three phase bridge...

The paper analyzes the development opportunities of solar systems in the Republic of Serbia. Renewable energy sources and their energy potential, such as solar energy, should be considered in order to meet the needs of consumers. Solar energy can be considered the most modern renewable energy whose utility is still developing, and it is not represe...

This article presents the aspects of solar radiation and the use of solar energy in Serbia. It also considers why Serbia does not use thermal conversion of solar radiation in spite of much greater potential comparing to the countries of the Western and Central Europe, which are leading in the use of solar energy. The low standard of living, low ele...

The spray dryer is very often applied in chemical and food - processing industries. This drying method includes suspension - spraying with the contents about 30 to 65% of dried substance. The drying period in most cases is only several seconds. The drying agent is the warm air. A model of momentum, heat and mass transfer in the atomization - swirle...

Measurement of a phase is necessary in a single or multiple balancing of rotating machines. Rate of phase shift is also very important because it can indicate presence of a critical speed. Amplification factor or log decrement in a certain mode can also be determined out of a rate of phase shift. Having a phase referent mark of complex rotating mac...

Reciklaža automobila podrazumeva različite procedure koje omogućavaju dobijanje proizvoda jednorodnih materijala (metali, plastika, guma, staklo), pogodna za proizvodnju novih materijalnih dobara. U radu je analiza reciklaže motornih vozila. Industrijska reciklaže vozila doprinosi održivosti i zaštiti životne sredine i uštedi energije. Korišćenjem...

Pneumatic transport is the most commonly performed transport of fine-grained and powder materials to manufacturing plants. It is considered that this is the most applicable transport within the manufacturing companies for the processing of grain and powder materials. The need for this kind of transport to be more sustainable, improved and to perfec...

This paper presents, based on the existing European standards, the assembled literature and the existing laboratory methods, results of the investigations of certain chemical-caloric parameters of the quality of the energetic pellets made of biomass after pressing and cooling of the compacted material. Based on the existing methods, the investigati...

In this article, the solar radiation in Vojvodina (a region which is located on the north of Republic of Serbia) is discussed. Its application up until now in this region and possible additional applications of solar energy in the future are reviewed. The aim of this work is to overview the energy and exploitation possibility in using solar energy...

This article shows the overview of renewable energy resources in Serbia, since many reseach shows that Serbia has great potential of RES (renewable energy source). It also has good conditions for electricity production and heat energy from renewable resources. The aim is to research and represent the development possibility of a country in a sector...

In this article the authors present an example of an agricultural farm that produces wheat corn, soya, and other plants. After harvesting granular products, large amounts of plant remains (biomass) are used as biofuel at the boiler in order to heat the agricultural farm. We present the results of research of energetic characteristics and boiler eff...

This paper discusses the process of increasing the effectiveness of CNC lathe for carrying out the appropriate experiments. Experiments are related to the plastics processing machine and programming fuzzy logic controller (FLC) for the requirements of machining. Input parameters of the FLCare obtained as a result of previous experimental parameters...

In modern life conditions, when emphasis is on environmental protection and sustainable development, fuels produced from biomass are increasingly gaining in importance, and it is necessary to consider the quality of end products obtained from biomass. Based on the existing European standards, collected literature and existing laboratory methods, th...

This paper will give details of described methods for the laboratory on the examination of biomass energy pellets after they have been through the pressing and cooling process of pressed material. These methods are based on previous experiments collected through the literature. The fundamentals of these experiments are examinations of shape and dim...

Due to the increase in price of fossil fuel, utilization of biofuel as a renewable type of fuel is getting more cost-effective. In this article, the research results of drying rice grain using corn grain and its waste as a biofuel are presented. Comparative tests were conducted using heating oil and biofuel.The testing was conducted on two batch gr...

This paper is an overview of the results of automatic monitoring of air quality parameters. An air quality assessment and development of criteria for evaluating air quality were performed on the basis of average daily data available, obtained from the automatic monitoring of air quality in the area of Smederevo. In order to enable more precise eval...

This paper presents the current approach of maintenance based on predictive maintenance. This approach is based on permanent monitoring of the plant in the on-line or off-line mode and simultaneous diagnostics, and this approach allows the competent authorities to have full access to the complete state of the plant at all times and to focus their a...

An experimental and theoretical research on the technology and application of contact drying on the rotating cylinder dryer is presented. Results of measurements of drying parameters of drying starch solution in real working conditions of drying are analysed. Based on tests numerical values of the coefficient of heat transfer, heat transfer model,...

In this paper the multi-criteria analysis of seven technological alternatives for agricultural irrigation was done, with the aid of PROMETHEE/GAIA methodology. Based on five criteria, which are considered important for decision makers in the selection, we made the ranking and selection of most optimal irrigation solution. On the basis of the offere...

In this paper are shown results of the research of turbo-aggregate - (steam turbine and generator). There are shown: basic theoretical research of system stability by the Niquist and Bode procedure, turbo-aggregate experimental details with measuring result, research result and their analysis. The goal of research is to evaluate dynamic state, sens...

This paper provides a description of under floor storage plant for the production of edible oil because of its complexity has almost all forms of transport material Also one of the reasons is the way of management of these transporters and storehouse work organization which was processed by computers. Transportation systems which are used in under...

The paper presents experimental and theoretical research related to problems of heat transfer in rotating cylinders. Given are the results of measuring the relevant parameters of the rotating cylinder systems in working conditions. The rotating cylinder is heated by steam from the inside. Given a description of the experimental apparatus with the m...

This work deals with the application of Promethee-Gaia methodology and the choice of three systems for drying paltry-seeds and powder materials pneumatic driers, spiral driers and rotation driers with a drum with regard to five different criteria. The analysis is based on the Promethee I method, the Promethee II method and the Promethee-Gaia method...

Spraying is very often applied in the chemical and food-processing industries. It includes the spraying of a suspension - spraying with a content of about 30 % to 65 % of a dry substance. The drying time is in most cases only several seconds. In this work the convective drying principle in warm air is presented. A mathematical model of momentum, he...

This paper gives the basic aspects of multicriteria analysis and PROMETHEE-GAIA methodology, which has successful usage in multicriteria decision making. Analysis was based on hypothetical example of customer decision making process during a purchase of new car tyre. The selection process was made among four types of tires equal dimension and same...

The biomass supply chain constitutes a system that is highly dynamic. The developed and proposed systems architectures for the management of the supply chains of typical industrial products do not directly apply to the case of the biomass supply chain. Nevertheless, it is imperative that a dedicated framework is needed according to the industrial s...

This paper presents the results of research which can be useful in designing and construction of such dryers in food industry. It refers to the technological and technical characteristics of the dryer, energy balances, coefficients of heat transfer and kinetic drying. The accomplishment of heat transfer in these systems is based on the principle of...

In this paper is presented production of sunflower, soy and rape in hectares, all being oil plants with excellent energy potential necessary in production of this eco-fuel. There are directions for development and the possibility that Serbia becomes a potential leader in the production of biodiesel. Studies, which are made for biodiesel, show that...

Experimental and theoretic researches are presented in this paper and they are implemented on the real industrial equipment of convection dryer for maize starch. The numeric values are given for optimum parameters of drying, energetics characteristics and balances as well as the coefficient of heat transfer. Heat transfer in these systems is accomp...

Job satisfaction is an historically popular variable in studies of vocational psychology. Employees' encounters with aspects of the work environment, such as work-related Stressors and the nature of work tasks can influence their satisfaction. Research presented in this paper indicates the existence of a personal or dispositional component to job s...

Experimental and theoretic research was conducted and the results were implemented in a real industrial environment on convection dryer with pneumatic transport of material. The numeric values are given for optimum parameters of drying, energetic characteristics and balances as well as the models of heat transfer. Accomplishment of the heat transfe...

An installation that contains 12 crystallizers, each unit of volume 35, m(3) Was analyzed in this paper. The effective time for crystallization from the moment when crystallizer is filled up until to the moment when the temperature of molasses falls to 36 degrees C was determined to be 45 h. Released heat from the crystallization process is used fo...

Experimental and theoretic research was conducted and the results were implemented in a real industrial environment on a convection dryer with pneumatic transport of material. The numeric values are given for optimum parameters of drying, energetic characteristics and balances as well as the models of heat transfer. Accomplishment of the heat trans...