Relative Perturbation Theory for Quadratic Eigenvalue Problems

In this paper, we derive new relative perturbation bounds for eigenvectors and eigenvalues for regular quadratic eigenvalue problems of the form $\lambda^2 M x + \lambda C x + K x = 0$, where $M$ and $K$ are nonsingular Hermitian matrices and $C$ is a general Hermitian matrix. We base our findings on new results for an equivalent regular Hermitian matrix pair $A-\lambda B$. The new bounds can be applied to many interesting quadratic eigenvalue problems appearing in applications, such as mechanical models with indefinite damping. The quality of our bounds is demonstrated by several numerical experiments.Comment: 27 page

Uticaj koncepcije mikser prikolica na uniformnost distribucije hraniva

The aim of this investigation was analysis of main mixing-distribution trailer working parameters. This will serve as a base for evaluation of possibilities for obtaining better feed preparation quality on farms, more uniform feed distribution, higher productivity and energy saving. Results have shown that different conceptions of mixing-distribution trailers have different quality of food distribution. Best uniformity of distribution was achieved by using of trailer with horizontal mixing rotor and with tiller for silage cutting and loading.Cilj ovog rada je analiza parametara rada savremenih mikser prikolica u uslovima eksploatacije, kako bi se sagledala mogućnost pripreme kvalitetnijeg obroka sa stanovišta mešanja i homogenizacije, ostvarila bolja ravnomernost distribucije pripremljenog hraniva, povećala produktivnost rada i smanjila potrošnja energije. Na osnovu podataka određeni su ravnomernost distribucije hraniva i prosečna količina izbačene mase. Analizom dobijenih rezultata konstatovano je da mikser prikolice sa horizontalnim rotorima daju bolje rezultate u pogledu ravnomernosti distribucije hraniva

Sinteza, NMR i DFT proračunavanja i ispitivanje antimikrobne aktivnosti Zn(II) kompleksa sa N-benziloksikarbonil-S-alaninom

In this study, the first complexes of Zn(II) with the N-benzyloxycarbonyl-S-alaninato ligand (N-Boc-S-ala) were synthesized. The new complexes were characterized by elemental analysis, conductometric measurements, IR. (1)H-NMR, (13)C-NMR and 2D-NMR spectroscopy. On the basis of the experimental data, tetrahedral geometry of the Zn(II) complexes was proposed. A very good agreement between the NMR and DFT calculated data was obtained. Investigation of antimicrobial activity of the newly synthesized complexes was also performed. It was established that [Zn(N-Boc-S-ala)(2)] was selective and acts only on Candida aibicans.U ovom radu su sintetizovani prvi kompleksi Zn(II) sa N-benziloksikarbonil-S-alaninato ligandom (N-Boc-S-ala). Kompleksi su okarakterisani elementalnom analizom, konduktometrijskim merenjem, IR, 1H-NMR, 13C-NMR i 2D-NMR spektroskopijom. Tetraedarska geometrija Zn(II) kompleksa pretpostavljena je na osnovu eksperimentalnih podataka. Dobijeno je veoma dobro slaganje između NMR i DFT podataka. Ispitivana je antimikrobna aktivnost novosintetizovanih kompleksa. Ustanovljeno je da je [Zn(N-Boc-S-ala)2] kompleks selektivan i da deluje samo na gljivu Candida albicans

Unapređene metode tretmana goveđeg stajnjaka

On a dairy farm where 2000 milk cows were maintained, crude solid manure deriving from the mixture of excrements and wheat straw, in the ratio of 1 kg straw: 9 l excrements, was subjected to aerobic and anaerobic fermentation. During the experiment, changes of temperature, volume, water contents organic matter contents, pH values, total macroelement contents and their low soluble forms were measured. Crude solid manure was converted by aerobic care into compost within 7 weeks; its volume was decreased by 2.3 times macroelement contents were decreased by 4 times as compared to unit volume of compost obtained by anaerobic care. Therefore, considerably higher economic effectiveness of compost production and application to cultivated areas was achieved.U radu su prikazani rezultati istraživanja koje je sprovedeno na farmi sa 2000 muznih krava. Mešavina naturalnog čvrstog stajnjaka i slame strnih žita u odnosu 1 kg slame sa 9 l ekskremenata, je izlagana aerobnoj i anaerobnoj fermentaciji. Praćene su promene temperature, zapremine, sadržaja vlage sadržaja organske materije, pH vrednosti i sadržaja teškorastvorljivih makroelemenata u masi. Naturalni čvrsti stajnjak je aerobnom fermentacijom prevođen u kompost tokom nege u trajanju od 7 nedelja. Njegova zapremina se smanjila 2.3 puta, a sadržaj makroelemenata je opao 4 puta, u poređenju sa kontrolnim tretmanom dobijanja komposta anaerobnom fermentacijom stajnjaka. Time je postignuta značajno veća efikasnost i ekonomičnost proizvodnje komposta i njegove primene na poljoprivrednim zemljištima

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

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

Primena konzervacijske obrade zemljišta u postrnoj proizvodnji kukuruza i soje

Adoption and improvement of different farming systems toward agricultural sustainability has a great social, economical and environmental importance. The base of sustainability is system productivity as ratio of output to input in a given system, measured in the same units, commonly as energy requirements. Therefore the objective of this study was to evaluate the aspect of energy requirements in the different conservation tillage systems regarding total energy consumption under conventional tillage. The appropriate measuring at the field conditions, conducted during summer period of 1997 on humoglay soil type on the plots with conventional tillage (CT - shallow plowing or double disking using heavy disc harrows + pre-sowing preparation), mulch tillage (MT- mulch subsoiler + mulch cultivator), and no-tillage (NT - direct sowing into wheat stubble covered with all amounts of straw residues using no-till planter John Deer Max emerge 2 with double disc openers) were included: operating speed, specific draft, draft per drill unit, working efficiency, power expenditure, total energy requirements, and slippage. The long-term data for the yield of maize (Zea mays L.) and soybean (Glycine max Merr.) following winter wheat (Triticum aestivum L.) in a double cropping system were collected from trials settled at the experimental field of Maize Research Institute in Zemun Polje, and from farms Stari Tamis and Omoljica, near Pancevo. The values of the analyzed energy parameters fluctuated under the different tillage methods along to increasing operating speed (8-12 km per hour). Conventional sowing were done under drafts 10,79-13,24 kN (2,69-3,31 kN per drill unit) with the power expenditure of 23,95 - 44,13 kW and working efficiency 1,04-1,56 ha per hour. On the plots following mulch tillage drafts were 10,30-13,20 kN and specific drafts 2,7-3,3 kN per drill unit, while engaged tractor power were 22,8-44,00 kW. Under the same speed interval significant increase of specific drafts 12,5-14,22 kN and 3,12-3,55 kN per individual drill were appointed using no-till planter. Engaged tractor power 27,7-47,4 kW were higher regarding to the values on the CT and MT plots. Besides total energy requirements (tillage practice, nitrogen, herbicides and irrigation), no tillage system can define as low-input technology that provides high productivity and sustainability on the basis of established input/output ratio.Prilagođavanje i unapređenje različitih sistema zemljoradnje u pravcu održivosti poljoprivredne proizvodnje ima ogroman socijalni, ekonomski i ekološki značaj. Osnova održivosti jeste produktivnost sistema izražena kao odnos inputa i autputa, najčešće u energetskom pogledu. Cilj ovog rada je zbog toga bio poređenje ispitivanih konzervacijskih sistema i konvencionalnog sistema obrade zemljišta sa energetskog i proizvodnog aspekta. Odgovarajuća merenja u poljskim uslovima, izvedena tokom leta 1997 godine na ritskoj crnici u sistemima konvencionalne obrade (CT-plitko oranje ili tanjiranje + predsetvena obrada zemljišta), zaštitne obrade (MT- obrada malč gruberom + malč setvospremačem) i direktne setve (NT - usejavanjem u strnište pokriveno celokupnom masom žetvenih ostataka korišćenjem John Deer-ove sejalice za direktnu setvu Max emerge 2) uključila su utvrđivanje brzine kretanja agregata, specifičnog otpora zemljišta, otpora po ulagaču, učinka, potrošnje snage i klizanja. U analizama su korišteni višegodišnji podaci o visini prinosa kukuruza i soje u postrnoj setvi iz poljskih eksperimenata izvedenih na oglednom polju Instituta za kukuruz u Zemun polju i sa gazdinstva Omoljica kod Pančeva. Vrednosti analiziranih parametara su varirale u različitim sistemima obrade pri povećanju brzine kretanja agregata (8-12 km h-1). Setva na klasičnom sistemu obrade zemljišta izvedena je pri otporu od 10,79-13,24 kN, odnosno 2,69-3,31 kN po ulagaču, uz angažovanu snagu traktora od 23,95 - 44,13 kW i učinkom 1,04-1,56 ha h-1. Na varijanti sa zaštitnom obradom zemljišta otpor raste sa povećanjem brzine agregata 10,30 na 13,20 kN, odnosno 2,7-3,3 kN po ulagaču, dok je angažovana snaga 22,8- 44,00 kW. U istom intervalu radne brzine konstatovan je porast specifičnog otpora pri direktnoj setvi od 12,5-14,22 kN, odnosno 3,12-3,55 kN po ulagaču, dok je angažovana snaga (27,7-47,4 kW) značajno prevazilazila vrednosti na CT i MT varijantama. Obzirom na ukupne zahteve u dopunskoj energiji (obrada zemljišta, azotna hraniva, herbicidi i navodnjavanje) i na bazi analiziranih odnosa energetskih inputa i autputa, sistem direktne setve se može definisati kao low-input tehnologija gajenja postrnih useva, koja osim visoke produktivnosti obezbeđuje i stabilnost poljoprivredne proizvodnje

Savremeni žitni kombajni u uslovima ubiranja kukuruza

The goal of the investigation was to analyze parameters and indicators of performance for modern combine harvesters, under conditions of PKB Corporation, as a basis to review the possibility for improved performance productivity, and decrease in fuel consumption, per unit of product. Based on investigations values for relevant parameters and indicators of fuel consumption up to 14.04 l/ha. i.e. 58.97 l/ha for performance of 24.2 ha/h and average speed of 8.0 km/h were established. The level of combine harvesters utilization was 0.70% with the potential for considerable improvement of this parameter by providing better coordination between the regime and working conditions.Cilj ispitivanja je analiza parametra i pokazatelja rada savremenih žitnih kombajna u uslovima ubiranja kukuruza, na osnovu čega će se sagledati mogućnosti povećanja učinka, produktivnosti rada, i smanjenja utroška goriva po jedinici proizvoda. Na osnovu ispitivanja utvrđene su vrednosti relevantnih parametara i pokazatelja, potrošnje goriva od 14,04 l/ha, odnosno 58,97 l/h pri učinku od 4,2 ha/h i prosečnoj brzini kretanja od 8,0 km/h. Stepen iskorišćenja kombajna iznosi 0,70%, s tim da bi se vrednost ovog stepena mogla znatno povećati sa boljom usaglašenosti režima rada i uslova rada

Mobilni sistemi za navodnjavanje kišenjem

This paper provides the synthesis of long lasting research of mobile raining irrigation systems in crop and vegetable production. The research included three mobile linear type irrigation devises, self-propelled rain wing and self-propelled rain gun. The paper is aimed at determining exploitation indicators, work quality indicators and yielding effects in cropping with emphasis to special characteristic of this irrigation systems in our production conditions in regard to favorable water resources. Field testing and exploitation monitoring in adequate seasonal use provided the indicators of energy consumption, productivity and work quality. - The productivity of linear mobile system was 2.47 ha/h, energy consumption 44.21 kWh/ha, at irrigation norm of 14.78 mm per passage. - The productivity of self-propelled rain wing was 0.55 ha/h, energy consumption 62.72 kWh/ha, at irrigation norm of 10 mm per passage. - The productivity of self-propelled rain gun was 0.12 ha/h, energy consumption 131.59 kWh/ha, at irrigation norm of 29 mm per passage. Extremely significant yield was recorded in greenpeas silage maize, seed maize, peas and potatoes in comparison to dry cropping and it was up to 105 % at some cultivation.Rad predstavlja sintezu višegodišnjih istraživanja navodnjavanja kišenjem mobilnim uređajima nekih ratarskih i povrtarskih kultura. Program istraživanja je obuhvatio tri mobilna uređaja za navodnjavanje tipa lineara samohodnog kišnog krila i samohodnog kišnog topa. Cilj rada je utvrđivanje eksploatacionih pokazatelja, pokazatelja kvaliteta rada i efekata navodnjavanja na prinos gajenih kultura s naglaskom na specifičnost ovih sistema za navodnjavanje u našim proizvodnim uslovima s obzirom na povoljne vodne resurse. Poljskim ogledima i eksploatativnim praćenjem u sezonama primene utvrđeni su pokazatelji potrošnje energije, proizvodnosti i kvaliteta rada: - Proizvodnost mobilnog linearnog sistema bila je 2,47 ha/h potrošnja energije 44,21 kWh/ha, pri normi navodnjavanja od 14,78 mm po prohodu. - Proizvodnost samohodnog kišnog krila bila je 0,55 ha/h, potrošnja energije 62,72 kWh/ha, pri normi navodnjavanja od 10 mm po prohodu. Proizvodnost samohodnog kišnog topa bila je 0,12 ha/h, potrošnja energije 131,59 kWh/ha, pri normi navodnjavanja od 29 mm po prohodu. Efekti na prinos boranije, silažnog kukuruza, semenskog kukuruza, graška i krompira su bili vrlo značajni u odnosu na suvo ratarenje i kreću se kod pojedinih kultura i do 105 %

Potencijali alternativne primene poljoprivredne avijacije

In this work was taken into consideration alternative use of agricultural aviation, with reference to using the newest technologies and highly qualified staff that executed mentioned technological operations. These high technologies are used in a fine and detailed way, with the strong scientific base. These scientific studies showed the potential possibilities of using aero planes, emphasizing the results of various scientific institutions and the success and efficiency of mentioned technological operations.U radu je razmatrana alternativna primena poljoprivredne avijacije, odnosno korišćenje najnovijih tehnologija i visokokvalifikovanog kadra za sprovođenje navedenih tehnoloških operacija, kod kojih se visoke tehnologije koriste na prefinjen i obuhvatan način sa jakom naučnom osnovom. Ova izučavanja su pokazala potencijalne mogućnosti primene aviona, isticanje rezultata raznih naučnih ustanova, kao i uspeh i delotvornost navedenih tehnoloških operacija