COMPUTATION OF QUASISTATIC ELECTROMAGNETIC FIELDS OF COMPLEX ELECTRIC POWER FACILITIES

Točan proračun niskofrekvencijskog kvazistatičkog elektromagnetskog polja značajan je za projektiranje naprava za prijenos i pretvorbu električne energije. U okviru ovog rada razrađena je teorijska podloga proračuna pomoću integralnih jednadžbi. Postupci rješavanja tih jednadžbi definirani su primjenom metode momenata i metode usklađivanja u točkama. Nepoznata raspodjela gustoće funkcije izvora na tankožičnim elementima je približena polinomima trećeg stupnja. Na pravokutnim plohama približenje nepoznate funkcije izvora realizirano je bilinearnim elementima. Razvijen je program za paralelni proračun elektromagnetskog polja temeljen na opisanoj metodi.Accurate computation of low-frequency quasistatic electromagnetic fields is important in the design of electricity transmission and conversion devices. This work presents the theoretical groundwork of a computation using integral equations. The procedures for solving these equations are defined by applying the method of moments and the point matching method. The unknown distribution of the source function density on the thin-wire elements is approximated by the third degree polynomials. On rectangular planes the approximation of an unknown source function is achieved by means of bilinear elements. A program has been developed for the parallel electromagnetic field computation based on the described method

THERMAL ANALYSIS OF BURIED HIGH-VOLTAGE CABLES

U okviru ovog rada provedena je spregnuta elektromagnetsko – termička analiza trofaznog sustava sastavljenog od tri jednožilna kabela u konfiguraciji delta. Sustav kabela analizira se u termički stacionarnom i nestacionarnom stanju, uzimajući u obzir nelinearnost provoda topline u tlu u okolini kabela. Složeni model prijenosa topline u tlu, uzrokovan isušivanjem tla u okolini kabela izveden je primjenom dvije zone različitih toplinskih vodljivosti.The present work includes the coupled electromagnetic/thermal analysis of a three-phase system composed of three single-core cables in trefoil configuration. The cable system is analyzed in thermally stationary and non-stationary state, taking into account the non-linearity of heat conduction in the soil surrounding the cable. The complex model of heat transfer in soil, caused by soil drying in the cable’s surrounding, has been made by applying two zones of different heat conductions

Grain Filling Variation in Winter Wheat, Barley and Triticale in Pannonian Environments

Knowledge about the comparative development and grain filling of winter cereals under different environmental conditions is important for stable and high yielding crop production. The objective of this work was to compare patterns of grain filling in bread wheat, barley and triticale grown in the Pannonian region, as well as to investigate relationships among grain filling parameters, time to anthesis and grain yield. The trials with 12 winter cereal genotypes were carried out in four successive seasons at the location Novi Sad, Serbia. Results of this study showed that all studied grain filling parameters were significantly influenced by species, cultivar, growing season, and species by growing season interaction. Longer duration of grain filling period and period to maximum grain filling were observed in triticale and wheat cultivars compared with six and two-rowed barley. Two-rowed barley cultivars had a higher grain filling rate than other cultivars. Furthermore, a negative association between time to anthesis and grain yield indicates that cultivars with the long pre-anthesis period are not recommended for the agro-ecological conditions of the Pannonian plain. Generally, medium early cultivars of small grain cereals had the highest grain weight within species and spike type, suggesting that medium early cultivars have a balanced ratio of pre-anthesis and grain filling period. High values of final grain weight in different growing seasons indicate that weather conditions in the Pannonian plain are mainly suitable for grain growth

Molecular and phenotypic characterisation of diverse temperate maize inbred lines in Southeast Europe

Maize (Zea mays L.) displays large genetic diversity created during the history of introduction from its Mexican centre of origin to other parts of the world and adaptation to a range of diverse environments. Despite such diversity, maize breeders use only a small portion of the available maize germplasm to develop modern hybrids. Broadening diversity of breeding collections by the introduction of new germplasm, as a source of favourable traits, requires its characterisation and classification of new germplasm into heterotic groups. The aim of this study was to estimate genetic diversity of maize breeding material from the Institute of Field and Vegetable Crops in Serbia, including previously uncharacterised inbred lines, elite lines with known pedigrees and historically important inbred lines. Microsatellite-based cluster analysis and principal coordinate analysis separated 96 inbred lines into six clusters, Iowa Stiff Stalk Synthetic (BSSS), Lancaster Sure Crop (LSC), Iodent (IDT) heterotic group, a cluster with unrelated independent inbreds and two clusters of miscellaneous germplasm crossed with inbreds of BSSS and Lancaster background. The microsatellites umc1035, bnlg666, dupssr23, umc1083 and dupssr10 contributed most to the differentiation between the groups. The largest values of molecular diversity parameters were detected in the BSSS group, following by the Lancaster and then the other groups. An analysis of variance showed that almost all traits significantly varied among the groups and between the years. The investigated lines demonstrated sufficient variation in most of the analysed phenotypic traits, proving suitable for further genetic studies. A principal component analysis based on agronomic traits differentiated inbred lines from the BSSS and Lancaster pools, but failed to separate the other groups. The characterisation and classification of genetic resources using microsatellite markers may assist hybrid breeding by efficient exploitation of heterotic patterns

Mogućnost prenošenja Leptosphaeria maculans i Leptosphaeria biglobosa semenom uljane repice

Stem canker (blackleg) is economically the most important disease of oilseed rape world­wide. This disease is caused by two species of pathogenic fungi of the genus Leptosphaeria: Leptosphaeria maculans (Desm.) ces. and de Not anamorf Phoma lingam (Tode. Fr.) Desmas, that causes stem canker and blackleg root and Leptospaeria biglobosa Shoem and Brun, that causes symptoms such as cancers of the upper part of the stem usually causing less damage, and can cause serious damage in countries with higher summer temperatures. Pathogenic fungi from one area to another are transmitted by ascospores and contaminated (infected) seed. In order to prove the modes of transmission of parasites, the test is done transmitting the parasite by seeds. Disinfected seeds of oilseed rape cultivars Quinta were submerged in the suspension of pycnospores. Submerged seeds were kept at 20 º C ± 1 º C and 12 h photoperiod for 48 h. After planting in plastic containers seeds were kept at 25 º C ± 1 º C and 12h photoperiod. In this experiment the following isolates were used: C-5, L-5, K-7, LJ-3, S-11, St-1, GS-3 and Lm as a reference isolate (L. maculans) fol­lowed by K-113, K-115 and Lb as a reference isolate (L. biglobosa). The symptoms were as­sessed after 7 and 14 days after emergence. Ratings were made with + which meant visible symptoms on cotyledons or hypocotyl and - what referred to healthy plants. After 7 days, the isolates (Lm, C-5, L-5, K-7, LJ-3, S-11, St-1, GS-3) were caused disease symptoms on plants of oilseed rape. This pathogenicity is reflected in the number of seedlings, leaf spots and stalk lodging cotyledons. At izolate Lb (reference isolate L. biglobosa) K-113 and K-115 after 7 and 14 days was not observed pathogenicity on rapeseed plants. The control variety seeds were soaked in distilled water. The trial was set in 6 reps, and pathogenicity of fungal isolates in relation to the control was tested using Dunette's test. After 14 days re-isolation of pathogen was done.Rak stabla (crna noga) je najznačajnije oboljenje uljane repice širom sveta. Bolest mogu prouzrokovati dve vrste patogenih gljiva iz roda Leptosphaeria: Leptosphaeria maculans (Desm.) ces. i de Not, anamorf Phoma lingam (Tode. Fr.) Desmas, koja prouzrokuje rak stabla i crnu nogu na korenu i Leptospaeria biglobosa Shoem and Brun, koja prouzrokuje simptome slične raku ali na gornjim delovima stabla obično prouzrokujući manje štete. Ozbiljnije štete mogu nastati u zemljama sa višim letnjim temperaturama. Patogene gljive se iz jedne oblasti u drugu prenose askosporama i zaraženim semenom. Da bi se utvrdili načini prenošenja parazita testirana je mogućnost prenošenja semenom. Dezinfikovano seme uljane repice, kultivara Quinta je potopljeno u suspenziju piknospora. Ovakvo seme je držano na 20ºC ± 1ºC i 12h fotoperiodu tokom 48 sati. Posle setve seme je preneto u plastične posude a temperatura čuvanja je bila 25ºC ± 1º C i fotoperiod od 12h. U ovom eksperimentu korišćeni su sledeći izolati: C-5, L-5, K-7, LJ-3, S-11, St-1, GS-3 i Lm kao referentni izolat (L. maculans) kao i K-113, K-115 i Lb kao referentni izolat (L. biglobosa). Ocena prisustva simptoma je rađena posle 7 i 14 dana od nicanja. Sa znakom + su se obeležavale biljke sa vidljivim simptomima na kotiledonima ili hipokotilu a znakom - biljke bez pojave simptoma. Posle 7 dana izolati Lm, C-5, L-5, K-7, LJ-3, S-11, St-1 i GS-3 su izazvali simptome bolesti na biljkama uljane repice. Patogenost se ogledala kroz broj oštećenih klijanaca, lisnih pega i povijenih kotiledona. Kod izolata Lb (referentni izolat L. biglobosa) K-113 i K-115 posle 7 i 14 dana nije primećena patogenost na biljkama uljane repice. Kontrolna varijanta semena je potapana u destilovanu vodu. Ogled je postavljen u 6 ponavljanja, i patogenost izolata gljive u odnosu na kontrolu je izražena Danetovim testom. Posle 14 dana izvedena je ponovna izolacija patogena

Association analysis of agronomic traits with microsatellites in maize inbred lines

Association analysis or linkage disequilibrium mapping is a method for identification of quantitative trait loci (QTLs) in a panel of divergent unrelated individuals based on historical recombinations during a crop's domestication and selection. It should account for the population structure, which can be the result of adaptation to local conditions or selection, to reduce the possibility of declaring false-positive associations. The aim of this study was to determine potentially significant and consistent associations between markers and agronomic important maize (Zea mays L.) traits using association analysis in a diverse breeding material that can be ultimately implemented in maize selection. To this end, 96 maize inbred lines were evaluated in field trials at three locations in Serbia for eleven agronomic traits and analysed with microsatellite markers. Twenty five microsatellites were used to assess the population structure using Bayesian model-based clustering method and to test the significance of associations between the markers and the traits with general (GLM) and mixed linear (MLM) models. The cluster analysis divided maize inbred lines in four subpopulations, corresponding to the BSSS (Iowa Stiff Stalk Synthetic), LSC (Lancaster Sure Crop), Iodent heterotic groups and exotic and independent germplasm. The models identified associations between twenty five microsatellite markers and eleven agronomic traits, resulting in 133 and 71 associations across the environments for GLM and MLM, respectively. Some of the identified marker-trait associations were significant and consistent in several environments. The associations stable in several environments were identified between the markers bnlg 1067 and two flowering traits; nc005 and bnlg434 and plant height, bnlg434 and ear height; bnlg1643 and umc1127 and leaf number, bnlg1360 and ear diameter; umc1019 and umc1506 and number of rows per ear; bnlg2305 and bnlg1451 and ear length, and between bnlg1175 and thousand-kernel weight. The results of this study indicate that these microsatellites could be used in marker-assisted selection of inbred lines, after validation of the marker-trait associations and testing combining abilities of the inbreds during hybrid development

Molekularni diverzitet i polimorfizam mikrosatelitskih markera savremenih hibrida kukuruza

The aim of this study was to estimate genetic diversity of 97 modern maize hybrids cultivated in Serbia with 12 microsatellite markers. In total, 89 alleles were detected, with the average of 7.4 alleles per locus. The polymorphic information content ranged from 0.42, for umc1792, to 0.81, for dupssr10, with an average of 0.64. The pairwise relatedness Ritland's values varied between 0.787 and -0.129. Eight markers were sufficient to differentiate hybrids with unique genotypes. A principal coordinate analysis distinguished early and late maturing groups of hybrids, although the observed differentiation between groups was low (Fst = 0.4%). Two markers, bnlg1556 and umc1075, contributed most to the discrimination between early and late genotypes. The values of parameters of molecular genetic diversity were higher in early than in late maturing hybrids, indicating broader genetic basis of the former. A high level of polymorphism of the markers indicates their suitability for fingerprinting.Cilj ovog rada bio je da se proceni genetički diverzitet 97 savremenih hibrida kukuruza koji se gaje u Srbiji pomoću 12 mikrosatelitskih markera. Od ukupno 89 alela, prosečno je utvrđeno 7.4 alela po lokusu. Vrednost polimorfnosti pojedinačnih lokusa (PIC) kretala se od 0.42, za marker umc1792, do 0.81, za marker dupssr10, sa prosekom od 0.64. Vrednosti Ritlandovog koeficijenta srodnosti varirale su između 0.787 i -0.129. Osam markera je bilo dovoljno da razdvoji hibride sa jedinstvenim genotipovima. Analiza glavnih koordinata razdvojila je grupu ranih i grupu kasnih hibrida, iako je diferencijacija između grupa bila niska (Fst = 0.4%). Dva markera, bnlg1556 i umc1075, su najviše doprinela razdvajanju ranih i kasnih genotipova. Vrednosti parametara molekularnog genetičkog diverziteta bile su veće kod ranih nego kod kasnih hibirida, što ukazuje na širu genetičku osnovu prve grupe. Visok nivo polimorfizma markera ukazuje na njihovu podobnost za određivanje molekularnog profila hibirida (tzv. fingerprinting)