Transient Phenomena during the Three-Phase 300MVA Transformer Energization on the Transmission Network

Connecting the transformer to the network may incur inrush current, which is significantly higher than the rated current of the transformer. The main cause of this phenomenon lies in the nonlinearity of the magnetic circuit. The value of the inrush current depends of the time moment of the energization and the residual magnetism in the transformer core. While connecting, the operating point of the magnetization characteristic can be found deep in the saturation region resulting in occurrence of large transformer currents that can trigger the transformer protection. Tripping of protection immediately after the transformer energization raises doubts about the transformer health. Inrush current can cause a number of other disadvantages such as the negative impact on other transformers connected on the same busbar; the increase of the transformer noise due to the large current value, the increase of the voltage drops in the network. The paper presents a simulation of the 300 MVA transformer energization using the MATLAB/Simulink software. 

Integration of Solar Power Plant in Distribution Network

This paper presents the integration of the solar power plant SE Gumiimpex, rated power of  1 MW in Croatian distribution network. Basic data of solar power plant are presented as well as the analysis of its impact on the distribution network. Power quality measurements, seven days before and seven days after the connection of PV plant to the grid are performed and obtained power quality indices are compared to those stated in the power quality standard HRN EN 50160/2012 and Croatian grid code. There are also presented results of the simulation of protection relays selection and coordinatio

Axial light emission and Ar metastable densities in a parallel plate dc micro discharge in steady state and transient regimes

Axial emission profiles in a parallel plate dc micro discharge (feedgas: argon; discharge gap d=1mm; pressure p=10Torr) were studied by means of time resolved imaging with a fast ICCD camera. Additionally, volt-ampere (V-A) characteristics were recorded and Ar* metastable densities were measured by tunable diode laser absorption spectroscopy (TDLAS). Axial emission profiles in the steady state regime are similar to corresponding profiles in standard size discharges (d=1cm, p=1Torr). For some discharge conditions relaxation oscillations are present when the micro discharge switches periodically between low current Townsend-like mode and normal glow. At the same time the axial emission profile shows transient behavior, starting with peak distribution at the anode, which gradually moves towards the cathode during the normal glow. The development of argon metastable densities highly correlates with the oscillating discharge current. Gas temperatures in the low current Townsend-like mode (T= 320-400K) and the high current glow mode (T=469-526K) were determined by the broadening of the recorded spectral profiles as a function of the discharge current.Comment: submitted to Plasma Sources Sci. Techno

Playing with fire: Exploring ceramic pyrotechnology in the Late Neolithic Balkans through an archaeometric and experimental approach

Addressing ceramic pyrotechnology plays a key role in understanding a wide range of cultural and social behaviours associated to pottery production. Firing is the process which transforms clay into ceramic, which is one of the most frequently preserved materials in the majority of Neolithic and later archaeological sites. Though firing temperatures and the functions of various pyrotechnological installations have been extensively investigated in archaeology, both have often been addressed separately. Most of our knowledge on firing structures and procedures in the Neolithic are still largely based on ethnoarchaeological evidence. To move forward, we need to consider all aspects involved in ancient pyrotechnology, together with use of additional investigative tools. This study aims to address Neolithic pottery firing from a diverse perspective that merges archaeometric analyses and experimental archaeology. To demonstrate the potential of this approach, we combined an archaeometric case study of pottery from the late Neolithic (5200–4800 BCE) from the site of Gradište-Iđjoš (Serbia) with experimental pit firings, likely one of the mostly frequently employed firing techniques used in prehistoric periods. Scientific analyses include X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), and ceramic petrography. These methods were run on both archaeological materials and experimental reproductions. Additionally, a detailed program of firing temperature monitoring, integrated observations on atmospheric conditions, soaking time, and duration were recorded to contribute to the study. The experiments enabled us to collect results useful for our understanding of the pyrotechnological knowledge of Neolithic potters from a technological and social point of view. In addition, they demonstrated the potential of a dedicated methodological framework for studying pottery firing that can be applied to other chronological and cultural contexts

Spatiotemporal profile of emission from oscillating dc micro discharges

The axial light distributions in parallel-plate dc microdischarges in argon show similar behavior to large scale discharges. Between the low-current Townsend mode and the high current glow mode exists a large region of currents where different oscillations appear and the dynamic Volt-Ampere characteristic shows hysteresis behavior. During the oscillations the maximum peak intensity moves closer to the cathode, which is characteristic for the abnormal glow regime even though the average current is considerably smaller.Comment: submitted to: IEEE Trans. Plasma Sci., Spec. Issue on Images in Plasma Sc

Ugt1a1 (ta)(n) promoter genotype: diagnostic and population pharmacogenetic marker in Serbia

The UGT1A1 enzyme is involved in the metabolism of bilirubin and numerous medications. Unconjugated hyper-bilirubinemia, commonly presented as Gilbert syndrome (GS), is a result of decreased activity of the UGT1A1 enzyme, variable number of TA repeats in the promoter of the UGT1A1 gene affects enzyme activity. Seven and eight TA repeats cause a decrease of UGT1A1 activity and risk GS alleles, while six TA repeats contribute to normal UGT I Al activity and non-risk GS allele. Also, the UGT1A1 (TA)(n) promoter genotype is recognized as a clinically relevant phannacogenetic marker. The aim of this study was to access diagnostic value of UGTIAI (TA) n promoter genotyping in pediatric GS patients. Correlation of the UGT1A1(TA)(n) genotypes and level of unconjugated bilirubin at diagnosis and after hypocaloric and phenobarbitone tests in these patients was analyzed. Another aim of the study was to assess phannacogenetic potential ofUGT1A1 (TA)(n) variants in Serbia. Fifty-one pediatric GS patients and 100 healthy individuals were genotyped using different methodologies, polymerise chain reaction (PCR) followed by acrylamide electrophoresis, fragment length analysis and/or DNA sequencing. Concordance of the UGT1A1 (TA)(n) promoter risk GS genotypes with GS was found in 80.0% of patients. Therefore, UGT1A1 (TA)(n) promoter genotyping is not a reliable genetic test for GS, but it is useful for differential diagnosis of diseases associated with hyperbilirubinemia. Level of bilimbin in pediatric GS patients at diagnosis wasUGT1A1 (TA)(n) promoter genotype-dependent. We found that the frequency of phannacogenetic relevant UGT1A1 (TA)(n) promoter genotypes was 63.0%, pointing out that UGT1A1 (TA)(n) promoter genoty ping could be recommended for preemptive pharmacogendic testing in Serbia

Seroepizootiološko-epidemiološka istraživanja i mapiranje infekcije Zapadnog Nila u Republici Srbiji

The disease caused by the West Nile virus (WNV) has been known since 1937 when it was described for the first time in Uganda. After spreading to Europe and the Middle East, the disease has changed its primary location. Today WN infection is a significant health problem in the world. As a result of the current epizootiological and epidemiological situation in Europe studies on the occurrence of WND were introduced in Serbia, also. The investigation on the presence of WNV antibodies was intensified in the period from 2008 to 2012. In this period a total of 3618 serum samples were tested from 18 localities (2736 animal sera from 8 different species and 882 human sera samples). The method applied was gel immunodiffusion and the representative samples were confirmed by the plaque reduction test (PRNT-90). Out of the total number of samples WNV antibodies were present in 3.97% horses, 0.93% dogs, 0.31% poultry and 1.36% man. In one horse serum sample there was a positive reaction with a positive control serum, thus indicating the presence of WNV antigen. The results have confirmed that WNV antibodies are present in 9 out of 18 tested locations in the Republic of Serbia. The percentage of seropositive samples varies from 0.42% in Pozarevac (horses and humans) up to 6.45% in Novi Pazar (dogs). Out of the investigated species the highest seropositivity was recorded in horses (3.97%), and lowest in poultry (0.31%). WNV is present and widespread in the Republic of Serbia, thus enabling distribution mapping.Bolest koju izaziva virus Zapadnog Nila (WNV) je poznata još od 1937. kada je po prvi put opisana u Ugandi. Posle širenja virusa u Evropu i na Bliski istok, bolest je promenila prvobitnu lokaciju. Danas je WN infekcija značajan zdravstveni problem u svetu. Kao rezultat trenutne epizootiološko-epidemiološke situacije u Evropi, uvedena su istraživanja prisustva WNV i u Srbiji. Istraživanja prisustva antitela za WNV intenzivirana su u periodu od 2008. do 2012. godine. U ovom periodu ukupno je ispitano 3618 seruma sa 18 lokaliteta (2736 seruma životinja, od 8 različitih vrsta i 882 seruma ljudi). Korišćen je metod imunodifuzije u gelu a reprezentativni uzorak potvrđen je testom neutralizacije plaka (PRNT- 90). Od ukupnog broja uzoraka na prisustvo antitela za WNV bilo je pozitivno 3,97% konja, 0,93% pasa, 0,31% domaće živine i 1,36% ljudi. U serumu jednog konja pojavila se pozitivna reakcija sa pozitivnim kontrolnim serumom, ukazujući na prisustvo antigena WNV. Dobijeni rezultati su potvrdili da su antitela za WNV prisutna u 9 od 18 ispitivanih lokacija u Republici Srbiji. Procenat seropozitivnih varira od 0.42% u Požarevcu (konji i ljudi) do 6,45% u Novom Pazaru (psi). Od ispitivanih vrsta najveća seropozitivnost je registrovana kod konja (3,97%), a najniža kod živine (0,31%). Raspoloživi podaci ukazuju da je WNV prisutan i značajno raširen u Republici Srbiji, što je omogućilo i mapiranje njegovog širenja

Multiuser Cognitive Radio Networks: An Information Theoretic Perspective

Achievable rate regions and outer bounds are derived for three-user interference channels where the transmitters cooperate in a unidirectional manner via a noncausal message-sharing mechanism. The three-user channel facilitates different ways of message-sharing between the primary and secondary (or cognitive) transmitters. Three natural extensions of unidirectional message-sharing from two users to three users are introduced: (i) Cumulative message sharing; (ii) primary-only message sharing; and (iii) cognitive-only message sharing. To emphasize the notion of interference management, channels are classified based on different rate-splitting strategies at the transmitters. Standard techniques, superposition coding and Gel'fand-Pinsker's binning principle, are employed to derive an achievable rate region for each of the cognitive interference channels. Simulation results for the Gaussian channel case are presented; they enable visual comparison of the achievable rate regions for different message-sharing schemes along with the outer bounds. These results also provide useful insights into the effect of rate-splitting at the transmitters, which aids in better interference management at the receivers.Comment: 50 pages, 15 figures, submitted to IEEE Transactions on Information Theor

Community-acquired pneumonia

Introduction: Community-acquired pneumonia (CAP) today, as well as a few decades ago, is a current medical problem considering the incidence and the mortality rate of the population, despite the availability of new and powerful antimicrobials and vaccines effectiveness. Objective: Analysis of outpatients diagnosed with pneumoniae, determination of the most common risk factors for their development, analysis of the success of outpatients' treatments and complications. Methods: Medical exams of 38 patients were analyzed. Each case is chosen by following previously prepared protocol, including patients with respiratory symptoms and infectious syndrome, positive auscultatory findings on the lungs which are radiologicaly confirmed and laboratory treated (SE, Le, FBC, the first and the tenth day of the therapy). Demographic data and associated illnesses, as well as a severity assessment of the illness, were made at the first medical examination, when pneumonia was suspected. Results: In the period from 01.11.2014 to 01.05.2015, there were 33 diagnosed pneumoniae. Associated illnesses, in population older than 65 years, were present in 92.85% of patients and some of them had two or three comorbidities. CRB65 proved itself as a good parameter in assessment of the disease severity for both groups. Applied antibiotic therapy proved to be effective in 80% of patients. There is no significant difference in pneumonia presentation with regards to gender and age. In data proccessing, descriptive statistics methods and no parameter x2 test were used for statistical significance assessment. Conclusion: All patients with clear indications should be hospitalized, but large percentage of patients can be treated in outpatints' facilities, with good patient cooperation. Also vaccination, as an available resource, seems to have not received a significant place in our environment

Contact process in a wedge

We prove that the supercritical one-dimensional contact process survives in certain wedge-like space-time regions, and that when it survives it couples with the unrestricted contact process started from its upper invariant measure. As an application we show that a type of weak coexistence is possible in the nearest-neighbor ``grass-bushes-trees'' successional model introduced in Durrett and Swindle (1991).Comment: 11 pages, 4 figure