Traktorsko-mašinski agregati za oranje teških zemljišta

This paper presents results of exploitation testing of three tractors-machinery couples in tillage. Basic of potential pulling characteristics of tractors and technical characteristics plough analyzing. Objective of the study was a tractors-machinery couples for heavy soils ploughing and their working parameters. The aim of the paper was, concerning the obtained results, to give the possibilities of energy savings and higher productivity.U radu je data anliza eksploatacionih ispitivanja tri traktorsko-mašinska agregata za osnovnu obradu zemljišta. Polazna osnova su potencijalne vučne karakteristike traktora i tehničke karakteristike analiziranih oruđa-plugova. Predmet istraživanja su agregati za osnovnu obradu teških zemljišta i njihovi radni parametri. Cilj rada je da se, na osnovu dobijenih rezultata istraživanja, ustanove mogućnosti uštede energije i povećanja produktivnosti rada

Tendencije razvoja poljoprivrednih traktora

General techniques development significantly affects agricultural tractors development. In mechanization of agriculture, three concepts of mobile systems development are present: tractors development, self - propelled chassis development, self - propelled machines development. In further tractors development, next tendencies are emphasized: tractors specialization, engine power increment and its development, gear box characteristics and ergonomically conditions improvement. Hydrostatic systems are much more applied. Actual science accomplishment, agriculture mechanization technical and technological performances, as well as satellites and computer technology, give possibilities of cultivation system defining, for every field and every soil type, particularly. All of these demands should be satisfied by specific tractor construction. Nowadays classic concept of tractor construction is still predominant (about 80 % of all designs), but more specified solutions are present, also.Opšti razvoj tehnike u velikoj meri utiče i na trendove razvoja poljoprivrednih traktora. U mehanizaciji poljoprivrede prisutne su tri koncepcije razvoja mobilnih sistema i to: razvoj traktora, razvoj samohodnih šasija, razvoj samohodnih mašina. Dalje tendencije razvoja traktora usmerene su ka: specijalizaciji traktora, povećanju snage motora i njegovom usavršavanju, poboljšanju karakteristika menjačkog prenosnika, poboljšanju ergonomskih uslova. Primena hidrostatičkih sistema sve je aktuelnija i sve više dolazi do izražaja. Današnja dostignuća nauke, tehničko-tehnološka rešenja poljoprivredne mehanizacije, zatim rešenja satelitske i kompjuterske tehnologije, pružaju mogućnosti da se za svaku parcelu i svako zemljište definiše način obrade. Na sve ove zahteve treba odgovoriti konstrukcijom traktora. Danas još uvek dominira klasičan koncept gradnje traktora (80 % svih rešenja), ali uz sve užu specijalizaciju i namenu

Model ocene kvaliteta obrade na bazi statistike zemljišta

Tillage exposes the soil to different mechanisms of direct or indirect mechanical decomposition, crucially changing its structure. Among others, a possible initial approach in controlling the quality of each specified operation and complete tillage process assumes establishing the functional relations between the operational parameters of applied mechanization and resulting probability density distribution of soil particle sizes. In this paper, the log-hyperbolic function is introduced and experimentally verified in describing the post-tillage soil particle sizes probability density distribution. Cultivation includes a variety of mechanical soil decomposing mechanisms. Consequently, quality control of a tillage concept incorporates the analysis of resulting soil particle sizes distribution, usually different from the normal Gaussian model. Following the common practice, shapes of these distributions are quantified in the paper by skewness S (SS) and flatness F (SF) factors. Data from five experiments gave clear relationships F=F(S) and SF=SF(SS), that might be useful in modeling and controlling the tillage quality.Obrada izlaže zemljište uticaju različitih mehanizama fizičke dekompozicije direktno ili indirektno, suštinski menjajući njegovu mehaničku strukturu. Između ostalih, jedan od mogućih pristupa u analizi kvaliteta svake predviđene operacije i procesa obrade u celini svodi se na uspostavljanje funkcionalnih veza između operativnih parametara primenjene mehanizacije i rezultujuće raspodele čestica obrađenog zemljišta. U ovom radu je, u svojstvu preliminarnog koraka, predložena i eksperimentalno potvrđena primenjivost log-hiperboličke funkcije za opisivanje raspodela veličina čestica obrađenog zemljišta. Obrada zemljišta je mehaničko usitnjavanje zemljišnih frakcija. Stoga je kontrola kvaliteta oranja koncept koji podrazumeva analizu veličina čestica zemljišta i funkciju njihove raspodele koja je obično drugačija od normalne (Gausovog modela). Sledeći opštu praksu, u izvesnim situacijama koriste se faktori asimetrije S (SS) i zaravnjenja F (SF). U radu se analiziraju rezultati pet eksperimenata gde se koriste faktori F=F(S) i SF=SF(SS), a rezultat modeliranja bi koristio za kontrolu kvaliteta rada

Analiza uticaja uslova eksploatacije traktora na njegovu pouzdanost

Tractors exploitation conditions are very complex. This demands different working regimes where each of these are manifested through reactive forces and moments influence on tractors subsystems. These influences are manifested through loads that need to be in accordance with static and dynamic straightest, material "tirenes" and wear resistances in order to have desired level of reliability. Considering the fact that material "tirenes" curves can serve only for evaluating the time of exploitation for an element in tractor subsystem, for more precise determination of period of usage an estimation of spares for certain exploitation conditions is needed. This paper deals with their classification in to six categories concerning the exploitation plot conditions and their influence on tractors.Uslovi eksploatacije traktora su brojni i raznovrsni što zahteva različite režime rada traktora, a svaki od njih se manifestuje kroz uticaj sila i momenata na njegove podsisteme i elemente. Opterećenja koje izazivaju ove sile treba da budu usaglašena sa statičkom čvrstoćom, zamorom i otpornosti na habanje elemenata kako bi se postigao zahtevani nivo pouzdanosti. Kako se na osnovu zamornih krivih dobijenih laboratorijskim ispitivanjem može samo oceniti vek nekog elementa u konstrukciji traktora, a ne i tačno odrediti za preciznije određivanje trajnosti elemenata predlaže se provera rezerve za određene uslove eksploatacije. S obzirom na brojnost i raznovrsnost uslova eksploatacije, u ovom radu je izvršena njihova klasifikacija u šest kategorija na osnovu karakteristika podloge po kojoj se traktor kreće odnosno uticaja podloge na različita radna opterećenja

Struktura izvoza i uvoza mleka i mlečnih proizvoda iz Srbije

The structure of the milk supply market depends on processing capacities in Serbia, which are more oriented to the production of dairy products pasteurized and sterilized milk and fermented dairy products (yoghurt, cream, sour milk, etc.), while the production of solid dairy products (cheeses, cream, spreads, butter, powdered milk, etc.) is significantly lower. Taking into consideration the current situation in Serbia regarding the primary production, purchase and processing of milk, an overview is given of the foreign trade balance of milk and dairy products and their participation in exports and imports. The analysis of the foreign trade of milk and dairy products for the period 2007- 2017 highlights products that are exported and have stable export tendencies, as well as scarce products which are imported and have a markedly negative balance sheet in the observed period. We also analyzed major export-import destinations of Serbia for the trade exchange of milk and dairy products, which primarily refers to the CEFTA countries, the European Union and the Russian Federation.Struktura tržišne ponude mleka zavisi od preradnih kapaciteta u Srbiji, koji su više orijentisani na proizvodnju mlečnih proizvoda pasterizovanog i sterilizovanog mleka i fermentisanih mlečnih proizvoda (jogurt, pavlaka, kiselo mleko itd.) dok je proizvodnja čvrstih mlečnih proizvoda (sirevi, pavlake, namazi, maslac, mleko u prahu itd.) značajno manja. Uzimajući u obzir aktuelno stanje u Srbiji u primarnoj proizvodnji, otkupu i preradi mleka, dat je kratak osvrt na spoljnotrgovinski bilans mleka i mlečnih proizvoda i njihovo učešće u izvozu i uvozu. Analizom spoljnotrgovinske razmene mleka i proizvoda za posmatrani period 2007-2017. godine ukazano je na proizvode koji se izvoze i imaju stabilne izvozne tendencije, kao i na deficitarne proizvode koji se uvoze i imaju izražene negativne bilanse u posmatranom periodu. Analizirane su i najvažnije izvozno- uvozne destinacije sa kojima Srbija ostvaruje trgovinsku razmenu za mleko i mlečne proizvode, pri čemu se to prvenstveno odnosi na zemlje CEFTA grupe, Evropske unije i Rusku Federaciju

Environmental geology and hydrology

Environmental geology is scientific discipline dealing with the interactions between humans and the geologic environment. Many natural hazards, which have great impact on humans and their environment, are caused by geological settings. On the other hand, human activities have great impact on the physical environment, especially in the last decades due to dramatic human population growth. Natural disasters often hit densely populated areas causing tremendous death toll and material damage. Demand for resources enhanced remarkably, as well as waste production. Exploitation of mineral resources deteriorate huge areas of land, produce enormous mine waste and pollute soil, water and air. Environmental geology is a broad discipline and only selected themes will be presented in the following subchapters: (1) floods as natural hazard, (2) water as geological resource and (3) the mining and mineral processing as types of human activities dealing with geological materials that affect the environment and human health

Obrada zemljišta kombinovanim oruđima

Paper present results of exploitation testing tractor-machinery couple in tillage, content plough and roller. Basic of working resistance in variant without roller and with roller and potential pulling characteristics of tractors analyzing. Objective of the study was a working parameters plough and tractors PKB corporation in our tractors machinery couples. The aim of the of researching was, concerning the obtained results, to give the possibilities of energy savings and higher productivity.U radu je data analiza eksploatacionih ispitivanja traktorsko-mašinskih agregata za osnovnu obradu zemljišta. Polaznu osnovu predstavljaju radni otpori pluga u varijanti bez i sa prstenastim valjkom i vučne karakteristike traktora. Tema istraživanja su radni parametari pluga i traktori PKB korporacije koji bi sa njim činili optimalni agregat za obradu. Smisao rada jeste da se na osnovu dobijenih rezultata istraživanja ustanove, mogućnosti za uštedu energije i povećanje produktivnosti rada

Uticaj tehnološko-tehničkog sistema aplikacije mineralnih đubriva na njihove fizičko-mehaničke osobine

Mineral fertilizers have a pivotal role in contemporary agricultural production, especially when seeking to exploit the full biological potential of crops. This paper presents the results of a three-year experiment on the distribution uniformity of different mineral fertilizer application systems. One of the objectives in this study was to define the physical and mechanical properties of four different types of mineral fertilizers and examine their changes during storage, transportation and application. A total of four fertilizers were taken into account: UREA, CAN, MAP and NP. The main physical properties, i.e. particle size, particle size distribution, friction coefficient, angle of repose and particle resistance, were analyzed on samples collected from the storage, the trailer (prior to application) and the field (after application). The results obtained show that fertilizers with a particle size distribution of 3.3 to 4.75 mm exhibit higher values of the angle of repose, friction and resistance. The lowest value of the angle of friction (17.53 0) was observed in the UREA fertilizer after application, whereas the highest angle of friction (24.37 0) was measured in the MAP fertilizer obtained from the storage. The values of the static repose angle varied depending on the fertilizer type and the place of sampling (storage, trailer or field). The lowest value of the static repose angle (30.34 0) was measured in the MAP fertilizer after application, whereas the highest static repose angle (36.91 0) was measured in the NP fertilizer from the storage. The NP fertilizer exhibited the highest value of the dynamic friction angle, whereas the lowest value of the dynamic friction angle was calculated for the UREA fertilizer. The NP fertilizer particles showed the highest resistance, whereas the UREA fertilizer particles were most susceptible to breakage.Savremena poljoprivredna proizvodnja se ne može zamisliti bez primene đubriva, posebno sa aspekta boljeg korišćenja biološkog potencijala rodnosti gajenih biljaka. U radu je prikazan deo rezultata trogodišnjih ispitivanja tehničko-tehnološkog sistema aplikacije mineralnih đubriva različitim tipovima centrifugalnih rasipača. Jedan od ciljeva istraživanja bio je i određivanje fizičko-mehaničkih osobina različitih tipova mineralnih đubriva, njihovih promena tokom samog procesa aplikacije i njihovog uticaja na kvalitet same aplikacije. U istraživanje su uključena četiri tipa mineralnih đubriva i to UREA, KAN, MAP i NP. Dobijeni rezultati tokom ispitivanja fizičko-mehaničkih osobina primenjivanih mineralnih đubriva pokazuju da đubriva koja imaju najveći procenat granula prečnika između 3,3 mm i 4,75 mm imaju najveće uglove trenja i nasipanja, kao i dobru otpornost prema lomu granule. Vrednosti ugla trenja su značajno varirale u zavisnosti od tipa đubriva i mesta uzorkovanja. Najniža vrednost, 17,53o je zabeležena kod UREE nakon aplikacije a najviša, 24,37o kod đubriva MAP iz skladišta na imanju. Vrednosti statičkog ugla nasipanja su takođe statistički značajno varirale u zavisnosti od tipa đubriva i mesta uzorkovanja. Najniža vrednost, 30,34o, je zabeležena kod đubriva MAP nakon aplikacije a najviša, 36,91o, je zabeležena kod NP đubirva iz skladišta. NP đubrivo je pokazalo i najviše vrednosti dinamičkog ulga trenja. Najniže vrednosti ovog parametra, 23,35o, imalo je đubrivo UREA. Čvrstoća granula je varirala u zavisnosti od tipa đubriva i od mesta uzorkovanja. Najviše vrednosti su zabeležene kod đubriva NP u svim fazama manipulacije dok su najniže vrednosti zabeležene kod đubriva UREA

Uticajni faktori navodnjavanja kišenjem na nagibima

Intensive plant production can not be imagined without irrigation. Support to this fact is that 18% of the total arable land in the world is irrigated, and the agricultural production from this area is equal to the total production of agricultural products from the rest of non irrigated area, which is 6 times larger. Irrigation in our country is under the real possibilities and needs, is provided on small areas and doesn’t influence significantly the agricultural production. Irrigation with raining on the slopes is very important because of potential of the hilly region in Serbia. Specific limitations of work on slopes, firstly because of protection from erosion, are directly influencing the selection and working regime of irrigation system.Intenzivna biljna proizvodnja nezamisliva je bez navodnjavanja. U prilog ovoj činjenici ide i podatak da se u svetu navodnjava 18% ukupno obradivih površina sa kojih se dobija isto onoliko poljoprivrednih proizvoda kao sa ostalih oko 6 puta većih nenavodnjavanih površina. U našoj zemlji navodnjava se ispod realnih mogućnosti i stvarnih potreba, obavlja se na malim površinama i ne utiče posebno na obim poljoprivredne proizvodnje. Navodnjavanje kišenjem na nagibima ima veliki značaj obzirom na potencijal brdskog područja u Srbiji. Specifičnosti uzrokovane ograničenjima u radu na nagibu, pre svega sprečavanju izazivanja erozije, direktno se reflektuje na izbor i režim rada sistema za navodnjavanje

Tractor Lifetime Assessment Analysis

In this paper, two different approaches in analyzing the tractor lifetime assessment are presented. The first one is based on reliability theory and the other one is based on the relevant experience that was implemented in the ASABE standards. In this way, the dependence of tractor reliability and lifetime on working conditions is presented through two models verified in the paper. Tractors from two different producers were analyzed. Experimental data were collected during the tractor working engagement at the fields of Agricultural Corporation Belgrade (ACB). Analyzing the obtained data it is possible to find the mismanagement in the tractor usage. Removing them it is possible to extend the period of tractor utilization. In this way the overall organization of tractor- machinery system on a farm can significantly be improved