Landspout across Novi Beograd, 24 may 2012: Synoptic analysis

In this study we have analysed a case of the landspout across Novi Beograd on 24 May 2012. We have used a synoptic analysis method in the research and the description of the landspout event is based on visual evidence and photographs. According to the available data, it can be concluded that there were favourable conditions for a landspout development since there was a process and an increased amount of instability. The landspout occured within the northeast stream which moved over Belgrade and further toward the southeast and west. Based upon synoptic data analysis, it can’t be said that there was a cold air advection. Surface air was warm enough, but not the air in the upper layers of the atmosphere. The conditions for a landspout development were favourable - high relative air humidity and increased vertical and horizontal air currents

Pojava trombe na Novom Beogradu 24. maja 2012. godine - sinoptička analiza

In this study we have analysed a case of the landspout across Novi Beograd on 24 May 2012. We have used a synoptic analysis method in the research and the description of the landspout event is based on visual evidence and photographs. According to the available data, it can be concluded that there were favourable conditions for a landspout development since there was a process and an increased amount of instability. The landspout occured within the northeast stream which moved over Belgrade and further toward the southeast and west. Based upon synoptic data analysis, it can't be said that there was a cold air advection. Surface air was warm enough, but not the air in the upper layers of the atmosphere. The conditions for a landspout development were favourable - high relative air humidity and increased vertical and horizontal air currents.U radu je prikazan slučaj pojave trombe 24.05.2012. na Novom Beogradu. U istraživanju je korišćen metod sinoptičke analize, a opis pojave trombe temelji se na vizuelnom opažanju i fotografijama. Prema raspoloživim podacima može se zaključiti da su uslovi za razvoj trombe bili povoljni, jer je postojao i proces i povećana energija nestabilnosti. Tromba se javila u sklopu severoistočne struje koja se premeštala preko Beograda dalje na jugozapad i zapad. Na osnovu analize sinoptičkog materijala, ne može se reći da se radilo o advekciji jako hladnog vazduha. Bilo je dovoljno toplote u prizemlju, ali ne i po visini. Postojali su povoljni uslovi za nastanak trombe - visoka vlažnost vazduha, izražena vertikalna i horizontalna strujanja

Analysis of impact of shaft speed and external load on the radial ball bearing lubrication regimes

Potrebno je odgovarajuće podmazivanje kotrljajućeg ležaja kako bi se smanjilo trenje između površina u međusobnom kontaktu i njihovo habanje. Mazivo bi trebalo da u potpunosti odvoji kotrljajuće elemente od staza. U radu su analizirane vrednosti koje utiču na efikasnost i režime podmazivanja, nakon čega se uvodi koeficijent režima podmazivanja. Ovaj koeficijent omogućava da se na jednostavan i brz način odabere optimalna kombinacija kotrljajućeg ležaja i maziva na osnovu poznate brzine osovine, spoljašnjeg opterećenja i radne temperature kotrljajućeg ležaja. Za pojedine ležajeve sa radijalnim kontaktom i određena maziva prikazana je zavisnost režima podmazivanja od brzine osovine i kontaktnog opterećenja.Appropriate lubrication of the rolling bearing is needed to lower the friction between the surfaces in mutual contact and their wear. A lubricant should completely separate the rolling elements from the raceways. The values that affect the efficiency and regimes of lubrication are analyzed in the paper, after which it is introduced a lubrication regime coefficient. This coefficient makes it possible to choose in a simple and fast manner an optimum combination of rolling bearing and lubricant based on the known shaft speed, external load, and rolling bearing operating temperature. For certain bearings with radial contact and certain lubricants, the lubrication regime dependence on the shaft speed and contact load is shown

Dendroindication of drought in Rogatica region (eastern Bosnia)

The aim of this study was to investigate the possibility of using the dendrochronological method in drought prediction in eastern Bosnia. As an indicator of drought, the standardized precipitation index (SPI) was used. In the wider area of Rogatica (eastern Bosnia), 11 core samples from trees were taken. The best connection between the width of tree rings and drought was shown by the sample of a 67-year-old European silver fir (Abies alba) from the mountain Boksanica. Removal of the biological trend (standardization) was performed by the autoregressive-moving-average (ARMA) method. Calculations showed that precipitation, i.e. drought in the summer months, is crucial for radial increment of the sample. The obtained results of our research have been confirmed in examples in the region and further

Ispitivanje kvaliteta semena ozime pšenice u periodu 2000-2005. godine

U radu su prikazani rezultati ispitivanja kvaliteta semena jedanaest sorti ozime pšenice: Pobeda, Evropa 90, NS Rana 5, Renesansa, Pesma, Proteinka, Balkan, KG-56, KG-100, Gruža i Takovčanka. Analizirano je 120 uzoraka semena ozime pšenice u prometu u periodu od 2000 do 2005 godine. Ocenjivani su sledeći parametri: procenat čistoće semena, masa 1000 semena, energija klijavosti, ukupna klijavost, vlažnost semena i broj zrna korova u 1000 grama semena. Seme je pripadalo kategoriji prve sortne reprodukcije. Rezultati su pokazali da je prosečna čistoća bila 99,3%, masa 1000 semena 41,4 g, energija klijanja 89%, ukupna klijavost 93%, vlažnost semena 11,9%, broj zrna korova u uzorcima je 0,5 i zdravstveno stanje ispravno, što zadovoljava zakonom propisane vrednosti

Zastupljenost korova u naturalnom semenu lucerke

In this study the presence of seeds of various weed species in natural alfalfa seed of different cultivars from different localities. In all studied cultivars of alfalfa and in all localities was found 25 different weed species, of which 14 species were perennial weeds, while the other 11 were annual weed species. Since dangerous perennial weeds which proliferate by vegetative and generative identified by (Sorghum halepense and Cirsium arvense). The highest number of weed seeds had annual species Picris echioides L. cultivar K-22 at the site Ratari 446 seeds. Also a large number of seeds was determined and the perennial species Cichorium intybus L. in all the cultivars of alfalfa. The lowest number of seeds were found in the species Rumex sp. four seeds and only the cultivar NS-Mediana at the site Bačko Gradište I, as with species Conium maculatum seven seeds only in the cultivar K-28 at the site Banatsko Karađorđevo. Most weeds species present (nine) was found in alfalfa cultivars NS-Mediana at the site Bačko Gradište I, and while the lowest number of weeds species (two) was found in the cultivar Banjalučanka at the site Kozarska Dubica.U ovom radu ispitivana je zastupljenost semena različitih korovskih vrsta u naturalnom semenu različitih sorata lucerke sa različitih lokaliteta. Kod svih ispitivanih sorti lucerke i na svim lokalitetima identifikovano je 25 različitih vrsta korova, od toga 14 vrsta su bili višegodišnji korovi, dok su ostalih 11 bile jednogodišnje korovske vrste. Od opasnih višegodišnjih korova koji se razmnožavaju generativnim i vegetativnim putem identifikovani su (Sorghum halepense i Cirsium arvense). Najveći broj semena korova imala je jednogodišnja vrsta Picris echioides L. kod sorte K-22 na lokalitetu Ratari (446). Takođe veliki broj semena utvrđen je i kod višegodišnje vrste Cichorium intybus L. i to kod svih ispitivanih sorata lucerke. Najmanji broj semena utvrđen je kod vrste Rumex sp. (četiri semena) i to jedino kod sorte NS-Mediana na lokalitetu Bačko Gradište I, kao i kod vrste Conium maculatum (sedam semena) samo kod sorte K-28 na lokalitetu Banatsko Karađorđevo. Najviše prisutnih korovskih vrsta (devet) utvrđeno je kod sorte lucerke NS-Mediana na lokalitetu Bačko Gradište I, dok je najmanji broj korovskih vrsta (dve) konstatovan kod sorte Banjalučanka na lokalitetu Kozarska Dubica

Uticaj različitih tipova kombajna za ubiranje kamilice na kvalitet ubiranja i visinu dobiti u proizvodnji kamilice

This paper presents the results of three conceptually different types of chamomile harvester and their impact on the quality of the harvested chamomile and profit during the production process. Three working modes of each harvester are considered and values of realized losses and the quality of harvested chamomile are determined. It was found that choosing the type of engaged harvester and its working mode can affect the quality of harvested chamomile, as well as the profit achieved in the entire production process. .U ovom radu su prikazani rezultati istraživanja tri koncepcijski različita tipa kombajna za ubiranje kamilice i njihov uticaj na kvalitet ubrane sirovine i ostvarenu dobit tokom procesa proizvodnje. Posmatrana su tri režima rada svakog od kombajna i utvrđeni su vrednosti ostvarenih gubitaka i kvaliteta ubrane kamilice. Utvrđeno je da se izborom tipa angažovanog kombajna i režima rada može uticati na kvalitet ubrane kamilice, kao i na ostvarenu dobit u celokupnom proizvodnom ciklusu.

Dendroindication of drought in Rogatica region (Eastern Bosnia)

The aim of this study was to investigate the possibility of using the dendrochronological method in drought prediction in eastern Bosnia. As an indicator of drought, the standardized precipitation index (SPI) was used. In the wider area of Rogatica (eastern Bosnia), 11 core samples from trees were taken. The best connection between the width of tree rings and drought was shown by the sample of a 67-year-old European silver fir (Abies alba) from the mountain Bokšanica. Removal of the biological trend (standardization) was performed by the autoregressive-moving-average (ARMA) method. Calculations showed that precipitation, i.e. drought in the summer months, is crucial for radial increment of the sample. The obtained results of our research have been confirmed in examples in the region and further. [47007

Organizovano korišćenje sredstava poljoprivredne mehanizacije

Serbian intention for membership in EU requires adoption of overall agricultural system according to the conditions of EU, making the own agricultural policy compatible to the common agricultural policy of EU. Creating of prosperous position for equal competition on international market is one of the main topics. Many of the recent analyses show that the most important issue for solving of this problem is decrement of agricultural mechanization application expenses. Starting from this, in this paper are analyzed production potentials of the Serbian agriculture, considering prosperous conditions for organized using of agricultural machinery in purpose of decreasing expenses as well as total expenses of the agricultural production, e.g. products otal expenses.Opredeljenje Srbije da postane član EU, nalaže prilagođavanje ukupnog agrarnog sistema uslovima EU, čineći svoju agrarnu politiku kompatibilnom sa zajedničkom agrarnom politikom EU. Stvaranje povoljne pozicije za ravnopravan ulazak u konkurentsku borbu na međunarodnom tržištu jedan je od glavnih zadataka. Mnoge dosadašnje analize i radovi ukazuju da je u rešavanju ovog zadataka najznačajnije snižavanje troškova primene sredstava mehanizacije. Polazeći od toga, u radu se analiziraju proizvodni potencijali poljoprivrede Srbije, radi sagledavanja pogodnosti uslova za organizovano korišćenje sredstava poljoprivredne tehnike u cilju smanjenja troškova njihove primene, a time i troškova ukupne poljoprivredne proizvodnje, odnosno cene koštanja poljoprivrednih proizvoda

The analyses of the relation of optical and nonoptical constants applied to material of interest in quantum electronics

The collecting, analysis and computation of data of optical and non-optical quantities of the material of interest in quantum electronics will be presented including the not so common relationships. The relationships between the optical and various non-optical quantities and the structure of the material are the topics of intensive theoretical and experimental work especially in the field of condensed matter. The transition to non-linear regions enhances the complexity. In spite of that, there are some simple relations for the zeroth and the first approximation. Dispersion relations, refractive index increments, reflection coefficient, angular dependencies and coherency of the data obtained by different measuring techniques as well as the corresponding theory will be analyzed. Some calculations for chosen materials will be presented, too. The computations of the refractive index values obtained according to Sellmeier's type relation will be also presented. These computations indicate wavelength ranges where the pulse compression is possible. Obtained results could help in selecting the appropriate material for the compression of the pulses of certain wavelengths or for resonant effects where the evaluation of the exact value or matching effects are important