Transmission Line Crisis Management

Višestruki trajni kvar dalekovoda uzrokovan klimatsko-atmosferskim utjecajima stvarnost su koja pogađa mnoge elektroenergetske sustave. Izravne štete zbog tih kvarova vrlo su velike, no marginalne su u odnosu na društvenu štetu uzrokovanu redukcijom potrošnje električne energije. Kako je neekonomično graditi dalekovode otporne na atmosferske utjecaje, treba nastojati preventivnim akcijama što efikasnije sanirati nastale štete, odnosno skratiti rokove popravaka. Radna skupina CIGRÉ (WG B2 13) priredila je Upute za djelovanje u kriznim situacijama temeljenim na iskustvima velikih poremećaja. I naša iskustva s višestrukim trajnim kvarom dalekovoda kao i značaj naše prijenosne mreže dovode do zaključka da bi bilo mudro da HEP OPS pristupi odgovarajućoj organizaciji preventive u dogovoru s HERA-om. U manjoj mjeri taj se problem odnosi i na sabirnice 400 kV.Multiple failures of transmission lines caused by climatic/atmospheric impact plague many electric power systems. Direct damage from such failures is quite huge, yet it is marginal compared with the social damage caused by the reduction in the supply of electricity. As it is not economical to construct weatherproof transmission lines, preventive actions should be employed the most effective restoration, or to reduce restoration time. A working group of CIGRÉ (WG B2 13) has prepared emergency guidelines based on the experience of large-scale disruptions. Our experience with multiple transmission line failure, as well as the importance of our power grid, lead to the conclusion that it would be wise for HEP OPS to begin with an appropriate organisation of preventive actions in agreement with HERA. To a lesser extent, this also applies to 400 kV buses

Testing the toughness of polypropylene filled with glass powder

Svrha rada je da se polimerni otpad prikaže kao sirovina ili na drugi način iskoristljiv materijal dobijen djelimičnim razdvajanjem komunalnog otpada. U radu je obrađena mogućnost ponovne upotrebe polipropilena recikliranjem uz dodatak staklenog praha, sa stanovišta žilavosti usljed udarnog opterećenja. Ispitivane su standardne epruvete, napravljene od osnovnog materijala - polipropilena i uz dodatak 0%, 5%, 10%, 15%, 20%, 25% i 30% staklenog praha granulacije manje od 0,5 mm, kroz šest ciklusa prerade. Izmjerene vrijednosti dale su mogućnost formiranja obrazaca promjene žilavosti posmatranog materijala sa različitim sadržajem stranog tijela, kroz cikluse prerade, što može pomoći u daljim istraživanjima i analizama.The purpose of this paper is to show polymer waste as a raw material or otherwise usable material derived from a partial separation of communal waste. This paper describes the possibilities of polypropylene re-use through recycling with addition of glass powder, from the point of view of toughness caused by impact load. Standard test specimens, made of basic material - polypropylene, with addition of 0%, 5%, 10%, 15%, 20%, 25% and 30% of glass powder with granulation less than 0,5 mm, have been tested through six processing cycles. The measured values gave a possibility of forming patterns for changes of the observed material with different content of additives, through processing cycles, which can be helpful in further research and analysis

Klimatske promene i nacionalna odbrana

Climate change, as one of the greatest challenges facing the contemporary society, continues to attract the attention of both political and scientific community for a rather long time. The variability of climate change consequences, as well as their effects on the environment and humanity, are on the agenda of most international conferences, and discussions on possible strategies for reducing their impact have been held both at national and international levels. However, most of these discussions are restricted mainly to the effects of climate change caused in the environment and, in this framework, to the effects that such changes might have on people's lives in terms of availability of basic supplies and resources. It had been rather long before the consideration of the impact of climate change exceeded the scope of environmental study, and in recent years the awareness of the impacts of climate change on the organization and functioning of national defense, especially in developed countries, has significantly increased. The changed nature of threats poses high standards before systems of defense in terms of capacities and capabilities for providing an effective response. The fact that climate change is affecting different segments of human civilization, which ultimately has an impact on the fulfillment of the mission of defense, necessarily imposes the need to put more efforts in addressing this issue in the future. Therefore, this paper aims, by considering some of the dominant climate change tendencies, to explore their impact on the functioning of the defense in the changing environmental conditions.Klimatske promene, kao jedan od najvećih izazova sa kojim se suočava savremeno društvo, već duže vreme ne prestaju da zaokupljaju pažnju, kako političke, tako i naučne javnosti. Varijabilnost posledica klimatskih promena, kao i njihovi efekti na životnu sredinu i čovečanstvo, nalaze se na agendi većine međunarodnih skupova, a diskusije o mogućim strategijama za redukciju njihovog uticaja vode se, kako na nacionalnom, tako i na međunarodnom nivou. Ipak, većina ovakvih diskusija ograničavala se pretežno na efekte koje klimatske promene izazivaju u životnoj sredini i, u okviru toga, na efekte koje takve promene mogu imati na život ljudi u smislu dostupnosti osnovnih namirnica i resursa. Prošlo je dosta vremena dok razmatranje posledica klimatskih promena nije izašlo iz okvira studija zaštite životne sredine, a u poslednjih nekoliko godina posebno je evidentan porast svesti o uticaju klimatskih promena na organizovanje i funkcionisanje nacionalne odbrane, posebno u razvijenim zemljama. Promenjena priroda pretnji postavlja pred sistem odbrane visoke standarde u pogledu kapaciteta i sposobnosti za efikasan odgovor na njih, a činjenica da klimatske promene pogađaju različite segmente ljudske civilizacije, što u krajnjoj liniji ima uticaja na ispunjavanje misije odbrane, nužno nameće potrebu da se ovoj problematici ubuduće posveti više pažnje. Zato, ovaj rad ima za cilj da, razmatranjem nekih od dominantnih trendova u kretanju klimatskih promena, analizira njihov uticaj na funkcionisanje odbrane u promenjenim ambijentalnim uslovima

Study of Green Nanoparticles and Biocomplexes Based on Exopolysaccharide by Modern Fourier Transform Spectroscopy

The intention of this chapter is to contribute in clarification of nanoparticle synthesis and biocomplexes based on exopolysaccharide, green synthetic method development, their physico‐chemical characterization by modern spectroscopy, as well as testing of their antimicrobial activity. Silver nanoparticles of polysaccharide type have scientific interest, but practical importance too, because of their application in pharmaceutical and cosmetic product development due to proven antimicrobial and antioxidant activities. On the other hand, the biocomplexes based on exopolysaccharides are important in treatment of biometal deficiency in human and veterinary medicine, as well as in metal ion transporting in organism. Despite a number of studies of this kind of complexes, the investigations of effect of their structure to pharmaco‐biological activity are still interesting. It is important that question of interaction between reducing and stabilizing agents with metal ions is still opened. In this respect, the presented chapter offers further progress in the examination of silver nanoparticles and cobalt biocomplex synthesis with dextran oligosaccharides and its derivatives (such as dextran sulfate and carboxymethyl dextran). The complex structure, spectroscopic characterization, and the spectra‐structure correlation have been analyzed by different Fourier transform infrared (FTIR) spectroscopic techniques combined with energy‐dispersive X‐ray (EDX), X‐ray diffraction (XRD), scanning electron microscopy (SEM), and surface plasmon resonance UV‐Vis methods

Učestalost, karakteristike i stepen izraženosti hipomineralizacije na prvim stalnim kutnjacima i sekutićima kod dece koja žive na području severnog dela Kosova i Metohije

Introduction/Objective: Molar-incisor hypomnineralization (MIH) is relatively common developmental anomaly characterized by hypomineralized enamel defects in the first permanent molars and incisors. The aim of this study was to determine the prevalence of hypomineralization of the first permanent molars and incisors in children aged eight and 10 years who live in the northern part of Kosovo and Metohija. Methods: The study included 712 respondents, 289 of whom aged eight (40.6%) and 423 of whom aged 10 years (59.4%). Criteria according to Weerheijm were used for diagnosis of hypomineralization and the severity of changes was determined. Results: The frequency of hypomineralized changes in the first permanent molars and incisors of the examined children in this area was 12.2%. It was lower in children aged eight years (10.7%) compared to those aged 10 (13.2%). Demarcated enamel opacity was more common in younger children, whereas both atypical restoration and tooth extraction due to hypomineralization were more common in older children. Mild form is more common in children aged eight years, whereas both severe form and severe form with extracted teeth are more common in children aged 10 years. The results indicate that the first permanent molars were most commonly affected by MIH changes. Conclusion: The percentage of the respondents with MIH changes in the northern part of Kosovo and Metohija, which is 12.2%, is not negligible and points to the necessity of early diagnosis in order to prevent and reduce the complications of the condition by timely prevention and treatment.Uvod/Cilj: Hipomineralizacija kutnjaka i sekutića (HKS) relativno je česta razvojna anomalija koja se karakteriše pojavom hipomineralizovanih defekata gleđi na prvim stalnim kutnjacima i sekutićima. Cilj ovog rada bio je da se ispita učestalost hipomineralizacije na prvim stalnim kutnjacima i sekutićima kod dece uzrasta osam i deset godina na području severnog dela Kosova i Metohije. Metode: U istraživanju je bilo uključeno 712 ispitanika – 289 uzrasta osam godina (40,6%) i 423 (59,4%) uzrasta deset godina. Za dijagnozu oboljenja primenjeni su kriterijumi po Weerhejim-u i određen je stepen izraženosti promena. Rezultati: Učestalost hipomineralizovanih promena na prvim stalnim kutnjacima i sekutićima kod ispitivane dece na ovom području iznosio je 12,2%. Kod dece od osam godina učestalost ovih promena je manja (10,7%) u odnosu na ispitanike od deset godina (13,2%). Ograničena zamućenost gleđi bila je učestalija kod dece mlađeg uzrasta, dok je kod dece starijeg uzrasta učestalija atipična restauracija i ekstrakcija zuba kao posledica hipomineralizacije. Blaga forma je učestalija kod dece od osam godina, dok je kod dece od deset godina učestalija teška forma, kao i teška forma koja uključuje i ekstrahirane zube. Rezultati pokazuju da su prvi stalni kutnjaci najčešće zahvaćeni hipomineralizovanim promena. Zaključak: Procenat od 12,2% ispitanika sa promenama HKS na području severnog dela Kosova i Metohije nije zanemarljiv. Ovakvo stanje ukazuje na neophodnost rane dijagnostike da bi se blagovremenom prevencijom i terapijom sprečile i ublažile komplikacije ovog oboljenja

ANTIMICROBIAL ACTIVITY OF METHANOL EXTRACTS OF FOUR PARMELIACEAE SPECIES

The methanol extracts of four Parmeliaceae lichens: Hypogymnia physodes, Evernia prunastri, Flavoparmelia caperata and Parmelia sulcata, were screened for their in vitro antimicrobial activity using a disk diffusion assay against 11 bacteria, fungi A. niger and yeast C. albicans. Aglomerative cluster analysis (AHC) of obtained activity showed that  H. physodes and E. prunastri extracts manifested stronger activity (diameter of inhibition zones ranged from 17 to 26 mm) than F. caperata and  P. sulcata extracts (diameter of inhibition zones ranged from 15 to 22 mm). Based on microorganisms´ susceptibility towards extracts two groups were distinguished: the first consisting of Gram negative bacteria (P. vulgaris and K. pneumoniae) and fungi (A. niger and C. albicans) and the second group including all Gram positive bacteria and three Gram negative bacteria (E. coli, S. enteritidis and  P. aeruginosa). F. caperata and E. prunastri extracts inhibited A. niger and C. albicans slightly more than Nystatin standard which suggests their possible use as active ingredients in phyto-therapeutics

Paraunitary oversampled filter bank design for channel coding

Oversampled filter banks (OSFBs) have been considered for channel coding, since their redundancy can be utilised to permit the detection and correction of channel errors. In this paper, we propose an OSFB-based channel coder for a correlated additive Gaussian noise channel, of which the noise covariance matrix is assumed to be known. Based on a suitable factorisation of this matrix, we develop a design for the decoder's synthesis filter bank in order to minimise the noise power in the decoded signal, subject to admitting perfect reconstruction through paraunitarity of the filter bank. We demonstrate that this approach can lead to a significant reduction of the noise interference by exploiting both the correlation of the channel and the redundancy of the filter banks. Simulation results providing some insight into these mechanisms are provided

Analysis of 14 C-bearing compounds released by the corrosion of irradiated steel using accelerator mass spectrometry

The combination of ion chromatography (IC) with accelerator mass spectrometry (AMS) was developed to determine the speciation of 14C-(radiocarbon) bearing organic compounds in the femto to pico molar concentration range. The development of this compound-specific radiocarbon analysis (CSRA) of carboxylic acids is reported and the application of the method on a leaching solution from neutron-irradiated steel is demonstrated. The background and the dynamic range of the AMS-based method were quantified. On using 14C-labelled standards, the measurements demonstrate the repeatability of the analytical method and the reproducible recovery of the main target carboxylic acids (i.e., acetate, formate, malonate, and oxalate). The detection limit was determined to be in the mid fmol 14C per L level while the dynamic range of the analytical method covers three orders of magnitude from the low fmol to the mid pmol 14C per L level. Cross contamination was found to be negligible during IC fractionation and was accounted for during eluate processing and 14C detection by AMS. The 14C-bearing carboxylates released from an irradiated steel nut into an alkaline leaching solution were analysed using the CSRA-based analytical method with the aim to check the applicability of the approach and develop appropriate sample preparation. The concentrations of 14C-bearing formate and acetate, the main organic corrosion products, were at a low pmol 14C per L level for convenient dimensions of the alkaline leaching experiment which demonstrates that compound-specific 14C AMS is an extremely sensitive analytical method for analysing 14C-bearing compounds. The content of total organic 14C in solution (TO14C) determined by the direct measurement of an aliquot of the leaching solution agrees well with the sum of the 14C concentrations of the individual carboxylates within the uncertainty of the data. Furthermore, the TO14C content is in good agreement with the calculated value using the corrosion rate determined from the 60Co release and the 14C inventory of the irradiated steel specimen

Neural networks in petroleum geology as interpretation tools

Abstract Three examples of the use of neural networks in analyses of geologic data from hydrocarbon reservoirs are presented. All networks are trained with data originating from clastic reservoirs of Neogene age located in the Croatian part of the Pannonian Basin. Training always included similar reservoir variables, i.e. electric logs (resistivity, spontaneous potential) and lithology determined from cores or logs and described as sandstone or marl, with categorical values in intervals. Selected variables also include hydrocarbon saturation, also represented by a categorical variable, average reservoir porosity calculated from interpreted well logs, and seismic attributes. In all three neural models some of the mentioned inputs were used for analyzing data collected from three different oil fields in the Croatian part of the Pannonian Basin. It is shown that selection of geologically and physically linked variables play a key role in the process of network training, validating and processing. The aim of this study was to establish relationships between log-derived data, core data, and seismic attributes. Three case studies are described in this paper to illustrate the use of neural network prediction of sandstone-marl facies (Case Study # 1, Okoli Field), prediction of carbonate breccia porosity (Case Study # 2, Beničanci Field), and prediction of lithology and saturation (Case Study # 3, Kloštar Field). The results of these studies indicate that this method is capable of providing better understanding of some clastic Neogene reservoirs in the Croatian part of the Pannonian Basin

Procena sadržaja i raspodele teških metala u površinskom sedimentu akumulacije 'Barje' - Srbija

In this study, the nature of the association of heavy metals (Fe, Co, Ni, Cu, Cd, Pb, Mn, and Zn) in sediments of the recent reservoir 'Barje' (Leskovac, Serbia) was investigated. The aim was to make the identification of their substrates, as well as to define the external factors (hydrological and anthropogenic affecting their distribution) which will contribute to a better understanding of the interactions that take place in the reservoir and predict the mobility of the investigated heavy metals. Chemical distribution of heavy metals was tested by using the method of sequential extraction and by data processing using statistical methods such as correlation, cluster and factor analysis. Based on the obtained results it can be concluded that major substrates of heavy metals are in the residual immobile fraction (Fe, Zn and Ni). Since the accumulation has a small organic substance content, Fe and Mn oxides are the most important binding substrates of heavy metals. Although it was determined that lead and cadmium are of the carbonate nature, their concentrations in the reservoir are negligible.Cilj ovog rada je da se ispitivanjem prirode asocijacija teških metala (Fe, Co, Ni, Cu, Cd, Pb, Mn, Zn) izvrši identifikacija njihovih supstrata u akumulaciji 'Barje' (Leskovac, Srbija), kao i da se definišu spoljni faktori (hidrološki i antropogeni koji utiču na njihovu raspodelu) što će doprineti boljem razumevanju interakcija koje se odigravaju u akumulaciji i prognozu mobilnosti na osnovu toga. Hemijska raspodela teških metala ispitana je korišćenjem metode sekvencijalne ekstrakcije i obradom dobijenih podataka statističkim metodama kao što su korelaciona, klaster i faktorska analiza. Na osnovu dobijenih rezultata može se zaključiti da se većina teških metala nalazi u rezidualnoj nepokretnoj frakciji (Fe, Zn i Ni). Zato što je u akumulaciji mali sadržaj organske supstance oksidi gvožđa i mangana su najznačajniji supstrati za vezivanje teških metala. Iako je utvrđeno da je olovo i kadmijum karbonatne prirode njihove koncentracije u akumulaciji su zanemarljivo male