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Yield and morphological traits of soybean depend on the variety, soil fertility, cultivation practice as well as the weather conditions in certain years. The aim of this research is to test the influence of different plant densities on yield, biomass, pod height and a number of mainstem nodes for three different soybean varieties. Variety Valjevka has achieved the highest yield with crop canopy of 500,000 plants, variety Sava at 450,000 plants and the variety Rubin with 400,000 plants per hectare. By increasing the density of crops the biomass is reduced and the first pod on the plant is higher in these three varieties. Prinos i morfološke osobine soje zavise od sorte, plodnosti zemljišta, agrotehničkih mera, kao i od vremenskih uslova u pojedinim godinama. Cilj ovih istraživanja je da se sagleda uticaj različitih gustina setve na prinos, masu biljaka, visinu mahuna i broj kolenaca na stablu za tri različite sorte soje. Sorta Valjevka je najviši prinos ostvarila pri sklopu od 500000 biljaka, sorta Sava pri 450000 biljaka, a sorta Rubin pri sklopu od 400000 biljaka po hektaru. Povećanjem gustine useva kod sve tri sorte soje smanjuje se masa biljaka i povećava se visina prvih mahuna na stablu soje.

The City of Belgrade is in the process of establishing a new waste management system through a public-private partnership. The project includes the construction of a municipal waste to energy recovery system. The recovery system is designed as a combined heat and power municipal solid waste mass burn incinerator. The impact of utilizing residual municipal solid waste for the generation of heat and power in lieu of coal and natural gas was assessed in terms of the reduction of greenhouse gas emissions. The contributions of energy derived from the waste to energy facility to the total energy consumption in Belgrade were also evaluated.

Mining of material by a bucket wheel excavator is a very complex physical physical-mechanical process. Indicators of the effectiveness of this process depends on a number of various factors, of which in particular may be emphasized: physical-mechanical characteristics of the material to be mined, mode of excavator operation and selection of block technological parameters, slice and cut, and the geometry of the buckets and teeth, etc. A particular problem occurs in the excavation of materials with increased strength, which is often the case in our opencast mines. Sizing of excavator specific digging forces towards smaller masses of extremely hard material is irrational and a solution should be sought either in the excavation of these masses by other equipment or by optimization of bucket wheel excavator operation i.e. in the selection of the optimal type of cut and parameters of slices in order to reduce resistance to digging, reducing energy consumption and reducing the dynamic effects on the structure of the bucket wheel excavator. Current research of this issue, it was found that certain improvements in the operation of the bucket wheel excavator on the mining of materials with increased strength can be achieved by optimizing of some structural and technological parameters, whose main goal is virtually increasing the available cutting forces of the excavator and maximum utilization of the available options with maximum protection of the excavator from the adverse impact of dynamic impacts during operation. Type and parameters of cut are the basic technological parameters that contribute to optimizing may affect: reduction of mining resistance in materials with the increasing strength, increasing the capacity of the bucket wheel excavator, minimizing energy consumption and more favorable dynamic behavior of excavator structure. It is also the subject of this thesis, and the primary goal through conducted researches is to define methodology to be used during selection and the optimal use of bucket wheel excavators in opencast mines in the working environment with the increased resistance to mining. Researches within this thesis were implemented at the theoretical and experimental levels. In this way was perceived an open and determined problem, was reviewed possible, selected optimal solutions, and carried out in practice checkups of results obtained in the concrete conditions of the working environment. Field tests, analysis of the obtained results and optimization of cutting parameters during the mining of materials with increased strength in the opencast mine Gacko has shown that the best effects of excavator operation are achieved with vertical cut and thickness of 0.20 m, width 0.30 m, i.e. with the slewing speed of bucket wheel boom of 24 m/min. It has been demonstrated that it is necessary to change the existing mining technology by the bucket wheel excavator, but also with further complex research to set up a methodology of optimizing the structure of the bucket wheel cutting elements. Otkopavanje materijala rotornim bagerom je veoma sloţen fiziĉko-mehaniĉki proces. Pokazatelji efektivnosti tog procesa zavise od velikog broja raznovrsnih ĉinilaca od kojih se posebno mogu istaći: fiziĉko-mehaniĉke karakteristike materijala koji se otkopava, reţim rada bagera i izbor tehnoloških parametara bloka, odreska i reza, geometrije vedrica i zuba itd. Poseban problem se javlja kod otkopavanja materijala povećane ĉvrstoće, što je ĉest sluĉaj na našim površinskim kopovima. Dimenzionisanje specifiĉne sile kopanja bagera prema manjim masama izuzetno ĉvrstog materijala je neracionalno i rešenje treba traţiti ili u otkopavanju ovih masa drugom opremom ili optimizaciji rada rotornog bagera tj. izboru optimalne vrste reza i parametara odreska u cilju smanjenja otpora na kopanje, smanjenja potrošnje energije i smanjenje dinamiĉkih uticaja na konstrukciju rotornog bagera. Dosadašnjim istraţivanjima ove problematike, ustanovljeno je da se izvesna poboljšanja u radu rotornog bagera na otkopavanju materijala sa povećanom ĉvrstoćom mogu postići optimizacijom odreĊenih konstruktivnih i tehnoloških parametara, ĉiji je osnovni cilj praktiĉno povećanje raspoloţive rezne sile bagera i maksimalno iskorišćenje raspoloţivih mogućnosti bagera uz maksimalnu zaštitu bagera od nepovoljnih dinamiĉkih udara tokom rada. Vrsta i parametri reza su osnovni tehnološki parametri ĉijom se optimizacijom moţe uticati na: smanjenje otpora kopanju u materijalima sa povećanom ĉvrstoćom, povećanje kapaciteta rotornog bagera, minimizaciju potrošnje energije i povoljnije dinamiĉko ponašanje konstrukcije bagera. To je ujedno i predmet istraţivanja ove disertacije, a osnovni cilj je da se kroz sprovedena istraţivanja definiše metodologija koja će se koristiti pri izboru i optimalnom korišćenju rotornih bagera na površinskim kopovima u uslovima radne sredine sa povećanim otporom kopanju. Istraţivanja u okviru doktorske disertacije su realizovana na teorijskom i eksperimentalnom nivou. Na taj naĉin je sagledan, otvoren i determinisan problem, sagledana moguća i odabrana optimalna rešenja i izvršena praktiĉna provera dobijenih rezultata u konkretnim uslovima radne sredine. Terenska ispitivanja, analiza dobijenih rezultata i optimizacija parametara reza pri otkopavanju materijala sa povećanom ĉvrstoćom na površinskom kopu Gacko pokazala su da se najbolji efekti rada rotornog bagera postiţu sa vertikalnim rezom debljine 0,20 m, širine 0,30 m, odnosno sa brzinom obrtanja strele rotora od 24 m/min. Dokazano je da je neophodno promeniti postojeću tehnologiju otkopavanja rotornim bagerom, ali i daljim kompleksnim istraţivanjima postaviti metodologiju optimizacije konstrukcije reznih elemenata rotora.

The immense attention that has been given to environmental issues in recent years can be attributed to a large amount of scientific evidence, according to which the existing and projected patterns of economic activities cause its degradation, which in turn questions the future of these economic activities. Development in the 21st century should be based on the rational use of natural resources, with minimal reversible damage to the environment. The development understood in this way is the starting point of the European Union's Common Agricultural Policy. Appropriate environmental measures have been prescribed for the realization of the planned developmental path, with the obligation to implement and adhere to them gaining more importance. Since its establishment, the Common Agricultural Policy has not focused on the environmental impact of agricultural production. More precisely, the possible environmental consequences of agricultural production on the environment had not been considered, which in turn led to significant problems. The problems that arose were the basis for the development of the environmental policy which defined the principles, measures and determinants for environmental protection and its improvement in the course of time. The analysis of measures and tools in the field of environmental protection, which are an integral part of the European Union's Common Agricultural Policy, was performed in order to point out their importance through reforms of the Common Agricultural Policy in preventing risks of environmental degradation and improving agroecosystem sustainability. In the part of the dissertation related to empirical research, in terms of agricultural development and environmental quality, the degree of interdependence of ecological and economic performances of agricultural production at the level of the EU member countries was analyzed. The EU countries have been classified into homogeneous groups through cluster analysis, according to the achieved level of environmental performance, thus showing the position of the countries between groups in relation to the achieved environmental performance, highlighting the recommendations for further direction of agricultural production and actions in combating climate change which is, needless to say, harmful to the environment. Based on the analysis of predictions of future values and the extent of environmental consequences, climate change has been recognized as an environmental indicator with the most influential negative impact on the environment.

Several unfavorable processes are taking place in the field of energy: large capacities of renewable energy sources (with variable and unpredictable availability) are being put into operation without detailed analises of its influence on electric power systems (EPS), large thermal and nuclear power plants (those who ensured the stability and reliability of EPS) are being closed, energy transmission systems are being cut off for political reasons as well as the import of some most important energy sources (natural gas, coal, oil). Those processes significantly change the role of hydropower plants in the EPS. All types of hydropower plants are becoming specialy important, especially those with water storage reservoirs and large installed capacities. Their role in regulating and ensuring the reliability of EPSs is significantly increasing. Beside the storage hydropower plants, pumped-storage hydropower plants become more important due to their possibilities to regulate the system in conditions of sudden changes of the power of wind and solar power plants,. The article discusses the processes in the world in terms of hydropower, the available hydropower potential in Serbia, as well as the real possibilities for its utilization. The most important hydropower systems remaining for construction are presented in the article. It is pointed out the necessity to clearly delineate which energy sources are really renewable and which contribute to the reduction of greenhouse gas. The importance of spatial planning which should protect the spaces necessary for the construction of hydropower systems is particularly emphasized. U svetu se odigravaju nepovoljni procesi u energetici: nedovoljno prostudirano se uvode u pogon velike snage obnovljivih izvora energije čija je raspoloživost vrlo promenljiva i nepredvidiva, zatvaraju se velike termoelektrane i nuklearne elektrane koje su obezbeđivale stabilnost i pouzdanost elektroenergetskih sistema, iz političkih razloga se prekidaju transferi energije i uvoz nekih ključnih energenata (prirodni gas, ugalj, nafta). Ti procesi radikalno menjaju ulogu hidroelektrana u elektroenergetskim sistemima. Sve vrste hidroelektana dobijaju na posebnom značaju, a posebno akumulacione hidroelektrane velikih instalisanih snaga. Značajno se povećava njihova uloga u regulaciji i obezbeđivanju pouzdanosti elektroenergetskih sistema. Zbog regulacije sistema u uslovima nagle promenljivosti snaga elektrana koje koriste vetar i Sunce, pored akumulacionih hidroelektrana velikih snaga, veliki značaj dobijaju i reverzibilne, pumpno akumulacione hidroelektrane. U članku se razmatraju procesi u svetu na planu hidroenergetike, raspoloživi hidroenergetski potencijali Srbije, kao i realne mogućnosti za njihovu realizaciju. Prikazuju se ključni hidroenergetski sistemi koji su preostali za izgradnju. Ukazuje se na neophodnost da se metodološki jasno razgraniči koji energetski izvori spadaju zaista u klasu obnovljivih izvora energije, i koji zaista doprinose smanjenju emisije gasova staklene bašte. Posebno se naglašava značaj da se prostornim planovina svih nivoa definišu i obezbede od devastacije i zauzeća prostori koji su neophodni za realizaciju hidroenergestkih sistema.

Although the issue of energy security is highly positioned on the scale of priorities of each country, for now there is no commonly accepted definition of energy security. The definitions of energy security can be divided into two groups. The first group consists of definitions that are focused on short-term approach where the focus is on energy supply. The second group is characterized by longterm approach, this type of definitions take a broader aspects of energy security as well as economic indicators and environmental indicators. Although there are a number of definitions and different approaches to energy security, the interest for methodology of calculation of energy security is not so large. Existing methods for quantitative expression level of energy security, in most cases are based on short-term approach, while methods based on the wider concept are mostly the composite indices that include a large number of individual indicators. In this way enable a more comprehensive approach, but practically speaking there are limits to measure because the big problem is the availability of data.

Previous energy strategies for Serbia had various goals in terms of renewable energy sources with the quantification of type of power plants by type, but the national energy planning did not go to the level of determining specific locations for power plants, namely photovoltaic. This caused difficulties for the responsible ministry and public companies to decide which power plants will be connected and which not. Additionally, due to a drop in investment costs, connection requests dramatically increased. In the beginning of 2023 applications for the construction of power plants totaling 14 GW in capacity were under review at public transmission company which further caused delays and stagnation in the construction of these power plants. At the same time, electricity prices for households and industries had increased by 18 and 27% respectively. During the year 2022, only 6 MW of new power plants were realized even with granting the monthly net-metering to the industry and households, which is far below the possible and realistic dynamic of Serbia's energy transition implementation. It was announced in early 2023, with the changes in legislative towards implementing the auctions principles, that the first permits will be issued for the construction of large photovoltaic power plants on land to progress towards meeting an overall capacity goal of 2-3 GW. To guide in selecting sites that will help meet this goal, we mapped 100 suitable photovoltaic power plant locations prioritized not only by energy yield, but also to prevent possible conflicts with other activities (i.e., agriculture, protected areas and cultural heritage). The mapping was carried out using available energy yield data, and geographically specific data of importance for the construction of larger photovoltaic power plants up to 10 MW in size. The 100 locations were selected as best among a much larger number of possible ones. These 100 sites occupy less than 25 km2 of land and would be enough to cover about 5% of household consumption in Serbia. Dosadašnje energetske strategije Srbije su imale različite ciljeve u pogledu obnovljivih izvora energije sa kvantifikacijom pojedinih tipova elektrana, ali nacionalno energetsko planiranje nije išlo do nivoa određivanja konkretnih lokacija, posebno za fotonaponske elektrane. Ovo je izazvalo poteškoće nadležnom ministarstvu i javnim preduzećima jer je pad investicionih troškova ohrabrio veliki broj aplikanata za dozvole za izgradnju elektrana na pogodnim lokacijama od ukupno 14 GW, što je dodatno izazvalo zastoje i stagnaciju u izgradnji ovih elektroenergetskih objekata na zemlji. U isto vreme došlo je do poskupljenja troškova snabdevanja električnom energijom za domaćinstva 18% i 27% za privredu tokom 2022. a iste godine kroz mehanizam neto-merenja realizovano je samo oko 6 MW novih elektrana što je kao rezultat daleko ispod mogućeg, realnog nivoa i neophodne brzine sprovođenja energetske tranzicije Srbije. Početkom 2023. godine, uz izmene zakona u pravcu sprovođenja aukcija, najavljeno je da će biti izdate prve dozvole za izgradnju velikih fotonaponskih elektrana na zemljištu i ulaganja u projekte veličine nekoliko (2-3) GW. Stoga je potrebno izvršiti mapiranje i odabiranje 100 lokacija fotonaponskih elektrana kako bi se bolje razumele pogodne lokacije ne samo sa stanovišta prinosa energije, već i kako bi se predupredili eventualni konflikti sa drugim aktivnostima (poljoprivreda, zaštićena područja, kulturno nasleđe). Mapiranje je sprovedeno korišćenjem raspoloživih podataka o energetskim prinosu, kao i geografski specifičnih podataka od značaja za izgradnju većih fotonaponskih elektrana do 10 MW. Odabrano je 100 najboljih lokacija među mnogo većim brojem mogućih. Količina proizvedene energije na površini koja zauzima manje od 25 km2 bila bi dovoljna da pokrije oko 5% potrošnje domaćinstava u Srbiji.

The importance of school buildings is considerable due to their function, character, purpose, and architectural design, and their refurbishment could lead to significantly better building energy performance. The current research was carried out on select school buildings and is based on a parametric study of the application of energy refurbishment of the thermal envelope (ERTE) and of select passive design systems (PD). The research analyzes the relevant parameters of planning and designing a Trombe wall system (TW), double skin facades (DSF), a green roof (GR), and shading – blinds (BL). In order to determine any possible benefits for increased energy-efficient heating and cooling, models of school buildings were designed using the EnergyPlus software. Climate data which represent a typical meteorological year for the city of Niš were used in the simulation. During modeling, the architectural features of the building were adhered to, as was the layout, the purpose, and the means of using the indoor space. The simulation results indicate that the individual application of the TW, DSF, and GR on the school building models leads to increased energy-efficient heating with decreased energy-efficient cooling. In contrast, the application of BL, independently or in combination with other PD systems, results in the significant increase in energy-efficient cooling. Adequate application of ERTE in combination with TW, DSF, and GR leads to increased energy-efficient heating, while application of ERTE in combination with BL and PD systems leads to the significant increase in energy-efficient cooling. Measures for increased energy-efficient heating and cooling include applying the TW+GR or the DSF+GR system, combined with BL, which confirms that combining numerous PD systems can contribute to significant energy efficiency improvements for the school building models. The application of proper thermal mass and glazing systems significantly increases energy - efficient heating. The application of a TW system, whose thermal mass is either a masonry wall or a 0,25m thick concrete wall, as well as the use of single glazing instead of triple glazing significantly increases energy-efficient heating. The application of a DSF system with an intermediate cavity 0,3 m wide and triple glazing leads to significantly increased energy-efficient heating, compared to applying a DSF system with an intermediate cavity 0.4 m or 0,5 m wide and single glazing. The results confirm that the application of a shading system significantly contributes to increased energy-efficient cooling for the building models. Application of a ventilated TW compared to a non-ventilated one, as well as of a ventilated DSF compared to a non-ventilated one, leads to a significant increase in energy-efficient cooling for the building models. The simulation results offer insight into which parameters provide significant energy efficiency for heating and cooling buildings and confirm the benefits of applying ERTE measures and select PD systems. The applied methodology could be modified, improved, and used in regions with similar climatic characteristics, which would provide a new approach to a decision-making process curbed by limited resources.

Today, most sophisticated numerical methods for predicting building energy consumption are implemented in building energy performance simulation tools. One of the possible ways to improve balance between building energy consumption and occupant thermal comfort in existing buildings is to use simulation-assisted operation of HVAC systems. Simulation-assisted operation can be formulated as a type of operation that implements knowledge of future disturbance acting on the building and that enables operating the systems in such a way to fulfill given goals, which in nature can often be contradictory. The most important future conditions on building energy consumption are weather parameters and occupant behavior and expectations of thermal environment. In order to achieve this type of operation, optimization methods must be applied, i.e. optimal daily operation strategies must be defined for HVAC systems. Methodology to create HVAC system operation strategies on a daily basis is presented in this doctoral dissertation. Methodology is based on using building energy performance simulation software EnergyPlus, data available in short-term weather forecasts, global sensitivity analysis, and for the purpose of this research, developed software. The developed software includes particle swarm optimization method, applied over the moving horizon (planning horizon) thus enabling the use of short-term weather forecasts, with necessary calculations being performed by the chosen simulation tool. Global sensitivity analysis, also performed with the same tool, is used in order to reduce number of input variables for the optimization process. The methodology is applied to real combined-type building in Niš. Objective function of the research is to reduce building energy consumption while satisfying constraints set on thermal comfort in one part of the building. Planning horizon is set to two days, while the resulting strategies are being implemented only on the first day of this horizon. The process repeats for every new planning horizon. The results of the methodology are experimentally verified in real building. The results show that applying this methodology leads to improvement in thermal comfort in most of the premises by using more energy, compared to usual building operation, so it offers a possibility to balance between building energy consumption and thermal comfort. Use of sensitivity analysis as a first step in determining daily building operation strategies, showed that the reduced number of input variables for the optimization would lead to similar thermal comfort and building energy consumption. Since the research was performed for the real building, building energy model calibration was performed in order to make model accurately reproduce the behavior of the real building.

The problem of fuel poverty is one of the key indicators of the decrease in housing affordability under conditions of climate change and rising energy prices. Besides rents, an important factor in determining the affordability of social housing is expenditure on energy in home and transport, and its reduction is necessary in order to ensure a long-term sustainability of this housing sector. In addition to reducing energy consumption, the key benefits of the introduction of energy efficiency measures in social housing include: reducing greenhouse gas emissions, promotion of social sustainability, improving living comfort and health of tenants, increasing the value of housing stock and promotion of innovative technologies. Energy efficiency is an essential element of the current housing policies and practice of social housing renewal and new construction in many developed countries, and based on the international experiences and recommendations, its importance has been recognized in Serbia. However, the existing technical requirements for planning, design and construction of social housing in Serbia fail to address specific guidelines for energy optimization which could be used when making planning decisions, and this is a significant constraint on improving future practice. Energy efficiency measures should be integrally implemented on all levels of the realization of the project, and the conditions for saving energy through the design and construction need to be set already in the phase of urban planning. Based on a review of related scientific and professional literature, in this paper the relevant spatial and physical criteria of energy efficiency in urban planning of social housing are defined. Taking into account the gap between the sustainability promotion in the planned future development of the social housing sector in Serbia and its practical application, the aim of the research is to contribute to creating a methodological framework for the improvement of local urban and architectural practice in this area. Prоblеm еnеrgеtskоg sirоmаštvа јеdаn је оd klјučnih pоkаzаtеlја smаnjеnjа pristupаčnоsti stаnоvаnjа u uslоvimа klimаtskih prоmеnа i rаstućih cеnа еnеrgiје. U оdrеđivаnju pristupаčnоsti sоciјаlnоg stаnоvаnjа, pоrеd zаkupninе, vаžаn fаktоr prеdstаvlјајu trоškоvi еnеrgiје u dоmаćinstvu kao i troškovi za prеvоz, te је njihоvо smаnjеnjе neophodno u cilju оbezbeđivanja dugоrоčnе оdrživоsti оvоg stambenog sеktоrа. Pоrеd smаnjеnjа еnеrgеtskе pоtrоšnjе, klјučnе dоbrоbiti uvоđеnjа mеrа еnеrgеtskе еfikаsnоsti u sоciјаlnu stаnоgradnju su: smаnjеnjе еmisiја gаsоvа stаklеnе bаštе, dоprinоs sоciјаlnој оdrživоsti, unаprеđеnjе stаmbеnоg kоmfоrа i zdrаvlја, uvеćаnjе vrеdnоsti stаmbеnоg fоndа i prоmоciја inоvаtivnih tеhnоlоgiја. Enеrgеtska еfikаsnоst je neizostavan element aktuelnih stambenih politika i prakse obnove i nove izgradnje socijalnog stanovanja u mnogim razvijenim zemljama, a pо uglеdu nа mеđunаrоdna iskustvа i prеpоrukе njen značaj prеpоznаt је i u Srbiјi. Ipak, pоstојеći tеhnički prоpisi zа plаnirаnjе, prојеktоvаnjе i grаđenje sоciјаlnоg stаnоvаnjа kod nas nеdovoljno razmatraju spеcifičnе smеrnicе u оblаsti еnеrgеtskе оptimizаciје kоје bi bilе upоtrеblјivе prilikоm izrаdе plаnskih rеšеnjа, štо prеdstаvlја znаčајnо оgrаničеnjе zа unаprеđеnjе budućе prаksе. Mere enеrgеtske еfikаsnоsti mоrаju sе sprovoditi intеgrаlnо krоz svе nivое rеаlizаciје prојеktа, а uslоvi zа uštеdu еnеrgiје krоz prојеktоvаnjе i grаđеnjе оstvаruјu sе vеć u fаzi urbаnističkоg plаnirаnjа. Nа оsnоvu prеglеdа rеfеrеntnе nаučnе i stručnе litеrаturе, u оvоm rаdu sе dеfinišu rеlеvаntni prоstоrnо-fizički kritеriјumi еnеrgеtskе еfikаsnоsti u urbаnističkоm plаnirаnju sоciјаlnоg stаnоvаnjа. Imајući u vidu rаskоrаk izmеđu prеpоrukа оdrživоsti u plаnirаnоm rаzvојu sоciјаlnоg stаmbеnоg sеktоrа u Srbiјi i njihоvе prаktičnе primеnе, cilј istrаživаnjа је dа dоprinеsе krеirаnju mеtоdоlоškоg оkvirа zа unаprеđеnjе dоmаćе urbаnističkе i аrhitеktоnskе prаksе u оvој оblаsti. Urednici: Mila Pucar, Marina Nenković-Riznić Posebna izdanja br.78