Convergence Properties of the Waveform Relaxation Method as Applied to Electric Power Systems

Several theoretical results are presented and simple examples examined in order to determine the suitability of waveform relaxation for transient power system simulation. This examination leads to two practical suggestions that can easily be satisfied for power systems. The first is to break the simulation interval into sections, the first of which should be narrow and be used to kill off errors in the initial guess that activate the stiff modes. The second is to partition the system into subsystems that are stable, as this not only aids convergence but ensures multirate numerical stability

Metal fume fever

Prikazana su dva slučaja cinkove groznice s osvrtom na etiopatogenezu, kliničku sliku i terapiju tog oboljenja. Dijagnoza je postavljena na osnovu anamneznih podataka i kliničke slike. Ukazano je na potrebu rigoroznije primene preventivnih mera, budući da je oboljenje najčešće posledica njihovog neprimenjivanja.Two cases of metal fume fever are described. The etiopathogenesis, clinical picture and therapy of the disease are dealt with. The diagnosis is based on anamnestic data and clinical picture. The necessity for strict preventive measures is pointed out, as the disease is mainly due to the lack of prophylaxis

Results of the 2015 national indoor radon intercomparison measurements in Serbia

Results and conclusions of interlaboratory comparison of indoor radon in 2015 in Serbia are presented. The participants were three accredited laboratories from Serbia: Serbian Institute of Occupational Health Dr Dragomir Karajovic, Laboratory for Radioactivity and Dose Measurements at the Faculty of Sciences, University of Novi Sad and Radiation and Environmental Protection Department, Vinca Institute of Nuclear Science. The laboratories make use of the same method for radon measurement, using charcoal canisters according to US Environmental Protection Agency (EPA) protocol 520/5-87-005. Calibration of detection efficiency was performed using EPA radium standard. Radon activity concentrations were determined on the basis of the intensity of short-living radon daughters, Bi-214 and Pb-214, gamma lines. The results of intercomparison were evaluated by using the u-test, which was calculated according to the International Atomic Energy Agency criteria. In this paper, not only limitations but also the advantages and possibilities of application of this method for measuring levels of human exposure to radon are discussed

Reduction of hexavalent chromium by bacillusspp. Isolated from heavy metal-polluted soil

Hexavalent chromium, Cr(VI), one of the major pollutants from industrial facilities, is very toxic and harmful for human health and environmental quaky. Due to the lack of conventional methods, bioremediation was recommended as an environmentally friendly and effective technique. The aim of this paper was the isolation, identification and selection of the microorganisms which are capable of Cr(VI) reduction in vitro. Heavy metal concentration, detected in four soil samples, within and around the former bicycle factory Wog" (Republic . of Slovenia), was measured using the ICP-OES method. Bacteria were isolated and tested for chromium tolerance using LB agar supplemented with various Cr(VI) concentrations, whilst Cr(VI) reduction and bacterial growth was determined using the LB liquid medium. From 53 bacterial isolates, five of them showed a tolerance of 1000 mg/L of Cr(VI). Those five isolates showed the capability of growth under various Cr(VI) concentrations (50-1000 mg/L). Initial Cr(VI) concentrations ranging from 50 to 100 mg/L were completely reduced by four bacterial isolates, whilst 500 to 1000 mg/L by Bacillus safensis 342-9. Using 16S rDNA and tuf gene sequence analyses, isolates 270-9R and 342-9 were identified as Bacillus safensis, isolates 351-9 and 270-9C as Bacillus subtilis subsp. subtilis, and 212-9 as Bacillus thuringiensis. These results indicated that these bacteria may be promising tools for remediation of metal-polluted sites

Dystrophia retinae pigmentosa sine pigmento as a cause of early working disability

Prikazana su tri bolesnika (dva zaposlena na poslovima elektrovarioca, jedan na poslovima ljevača-talioca) kod kojih se radilo o nedijagnosticiranoj nasljednoj bolesti Dystrophia retinae pigmentosa sine pigmento prije zaposlenja, a kasnije je ta bolest bila razlog za promjenu poslova i radnih zadataka nakon kratkog radnog staža.Three cases of dystrophia retinae pigmentosa sine pigmento are described. In two welders and one founder the disease, which failed to be diagnosed at preemployment screening examination. appeared after a short period of work causing disability. The workers had to be removed from their workplaces and changed occupation

First steps towards national radon action plan in Serbia

Radon problem has a special attention in many countries in the world and the most of them have established national radon programmes. The radon issues in Serbia have not been approached in a systematic and organized way. Currently, there are many research groups and institutions working in radon field, and it is a good basis to integrate all these activities into a comprehensive national programme to define the strategic objectives and action plan for the next few years. Also, Serbia as a candidate for membership in the EU is obliged to harmonize its legislation, including the field of radiation protection in which the radon issues has an important role. In this report, a brief history of radon research, present status and plans for the future activity on radon issues in Serbia are presented. Regarding the long-term plans, the establishment and implementation of the Radon Action Plan with the primary goal of raising awareness about the harmful effects of public exposure to radon and implementing a set of measures for its reduction. In that sense, the synergy between the national, regional and local organizations responsible for public health and radiation protection must be achieved

Revitalizacija i informaciona integracija proizvodnih resursa u cilju podizanja konkurentnosti TRAYAL korporacije na međunarodnom tržištu – rekapitulacija ukupnih rezultata na projektu TR-6362A

U uvodnom delu ovog rada izloženi su organizacija, osnovni sadržaj planiranih istraživanja i ciljevi na projektu TR-6362A koji su zajednički realizovali Mašinski fakultet Univerziteta u Beogradu, Trayal Korporacija iz Kruševca i Informatika A.D. iz Beograda. Dalje se detaljno navode ključni rezultati projekta ostvareni u trogodišnjem istraživačkom periodu koji su realizovani sa globalnim ciljem sistematskog unapređenja stanja izabranih proizvodnih resursa Trayal korporacije za domen mehaničke prerade elastomera, upravljanja proizvodnjom i praćenja kvaliteta proizvoda. Pored toga u radu se navode i neka opšta zapažanja vezana za stanje Trayal korporacije i faze kroz koje je prolazila u procesu svojinske transformacije. Na kraju, navode se dalje perspektive praktične primene ostvarenih rezultata i mogućnosti nastavka saradnje po ovom osnovu u narednom periodu