34 research outputs found
Ukupna taložna tvar na podruÄju Primorsko-goranske županije u razdoblju 1975.-2008.
Dustfall measurements in Primorsko-goranska county started in 1975 in the Bakar Bay (Site 2 - Bakar and Site 3 - Kraljevica). The measurements were extended to the city of Rijeka (Site 1 - Rijeka) in 1982, to the nearby islands (Site 4 - Krk and Site 5 - Cres) in 1986, and inland to Gorski Kotar (Site 6 - Delnice and Site 7 - Lividraga) in 1995. This article brings the results of dustfall measurements from 1975 to 2008. Dustfall was low in the city, the nearby islands, and Gorski Kotar. Recommended and limit values
were occasionally exceeded in the Bakar Bay due to emissions from the coke plant and harbour at Site 2 (1979-1997) and from the shipyard at Site 3. Lead content in the dustfall was below the national limits, save for two occasions at Site 2. Deposition of sulphur and nitrogen at the inland sites were below the respective critical load values.Ispitivanja ukupne taložne tvari u Primorsko-goranskoj županiji zapoÄela su 1975. godine na podruÄju Bakarskog zaljeva. Mjerenja su se 1982. god proÅ”irila na grad Rijeku, 1986. na otoke Krk i Cres, a 1995. i na podruÄje Gorskog kotara. U radu su prikazani rezultati mjerenja ukupne taložne tvari u razdoblju 1975.-2008. na sedam odabranih postaja: u gradu Rijeci, dvije na podruÄju Bakarskog zaljeva (Bakar i Kraljevica), dvije na otocima (Krk i Cres) te dvije u Gorskom kotaru (Delnice i Lividraga). Analizirano je kretanje prosjeÄnih godiÅ”njih vrijednosti ukupno istaloženih tvari te u njima prisutnih koliÄina sagorivog pepela, sulfata, nitrata, amonija i olova. Na podruÄju grada Rijeke, otoka Krka i Cresa te Gorskog kotara
koliÄina ukupne taložne tvari je niska. KoliÄine ukupne taložne tvari povremeno su prelazile preporuÄenu graniÄnu vrijednost u Bakru (1979.-1994.), zbog emisija iz koksare i iz luke za rasuti teret te u Kraljevici, gdje se osamdesetih godina osjeÄao utjecaj koksare u Bakru, a od sredine devedesetih pojaÄani rad u brodogradiliÅ”tu. KoliÄine olova u taložnoj tvari su niske na svim postajama, osim povremenih skokova u Bakru, kada su prijeÄene preporuÄene vrijednosti. KoliÄine istaloženog sumpora i duÅ”ika na podruÄju
Gorskog kotara ispod su odgovarajuÄih vrijednosti kritiÄnog optereÄenja za ispitivana podruÄja
Upravljanje vjetroagregatom otporno na oÅ”teÄenja kaveza asinkronog generatora
Wind turbines are usually installed on remote locations and in order to increase their economic competence malfunctions should be reduced and prevented. Faults of wind turbine generator electromechanical parts are common and very expensive. This paper proposes a fault-tolerant control strategy for variable-speed variable-pitch wind turbines in case of identified and characterised squirrel-cage generator rotor bar defect. An upgrade of the torque control loop with flux-angle-based torque modulation is proposed. In order to avoid or to postpone generator cage defects, usage of pitch controller in the low wind speed region is introduced. Presented fault-tolerant control strategy is developed taking into account its modular implementation and installation in available control systems of existing wind turbines to extend their life cycle and energy production. Practical implementation aspects such as estimation of variables used in control and estimate errors are considered and respected in operation, as well as fault-induced asymmetries. Simulation results for the case of a megawatt class wind turbine and the identified rotor bar fault are presented.Vjetroagregati se obiÄno postavljaju na udaljene, nepristupaÄne lokacije te je potrebno sprijeÄiti nastanak kvarova da bi se poveÄala njihova ekonomska konkurentnost. Kvarovi elektromehaniÄkih dijelova generatora vjetroagregata Äesti su i vrlo skupi. U ovom radu predstavljen je koncept upravljanja vjetroagregatima s promjenjivom brzinom vrtnje i zakretom lopatica za sluÄaj identificiranog i okarakteriziranog oÅ”teÄenja kaveza asinkronog generatora. Predložena je nadogradnja na postojeÄi algoritam upravljanja momentom zasnovana na njegovoj modulaciji s obzirom na položaj magnetskog toka generatora. Da bi se izbjeglo ili usporilo Å”irenje napuknuÄa kaveza generatora, predložena je primjena regulacijskog kruga za zakret lopatica i u režimu rada vjetroagregata ispod nazivne brzine vrtnje. Predstavljena strategija upravljanja razvijena je uvažavajuÄi moguÄnost modularnog nadovezivanja na postojeÄe metode upravljanja veÄ postavljenih vjetroagregata s ciljem produženja njihova životnog vijeka i poveÄanja proizvodnje energije. Razmatrani su i uvaženi aspekti vezani uz praktiÄnu izvedbu, kao Å”to je estimacija varijabli koriÅ”tenih u upravljaÄkom algoritmu i pripadajuÄe pogreÅ”ke estimata, kao i nesimetrije uzrokovane nastankom kvara. U radu su dani simulacijski rezultati za sluÄaj vjetroagregata iz megavatne klase s dijagnosticiranim napuknuÄem kaveza rotora
Structure of 24Mg excited states and their influence on nucleosynthesis
The main idea of the two presented experiments is to study the decay of resonances in 24Mg at excitation energies above the 12C+12C decay thresh- old, in the astrophysical energy region of interest. The measurement of the 12C(16O,Ī±)24Mg* reaction was performed at INFN-LNS in Catania. Only the Ī±+20Ne decay channel of 24Mg is presented here, because it was a motivation for conducting a new experiment, a study of the 4He(20Ne,4He)20Ne reaction, performed at INFN-LNL in Legnaro. Some preliminary results of this measurement are also presented
13C+4He resonant elastic scattering on a thick gas target
Resonant elastic scattering of 13C on a thick 4He target has been measured. Reaction products from 13C(4He, 4He) were detected at several beam energies and gas pressures. Raw yield was efficiency corrected using Monte Carlo simulations and an averaged yield spectrum was produced. The observed peaks correspond well to the previously measured elastic scattering data
Analysis of states in <sup>13</sup>C populated in <sup>9</sup>Be + <sup>4</sup>He resonant scattering
Measurements of 9Be+Ī± resonant scattering have been performed using the thick-target approach with a 4He gas volume and a large area silicon strip detector. 9Be beam energies in the range 12 to 21.4 MeV were used to measure the 13C excitation energy spectrum between 13.2 and 16.2 MeV. An R-matrix analysis has been performed to characterize the spins and widths of 13C resonances, some of which have been proposed to be associated with a 3Ī±+n molecular band
Study of 24Mg resonances relevant to carbon burning nucleosynthesis
We have studied the decays of the resonances of 24Mg at excitation energies 1ā6 MeV above the 12C+12C decay threshold, using the 12C(16O,Ī±)24Mg* reaction at E(16O) = 94 MeV. Some preliminary results are presented and further analysis is in progress
Clusters in neutron-rich light nuclei
Due to their high selectivity, transfer and sequential decay reactions are powerful tools for studies of both single particle (nucleon) and cluster states in light nuclei. Their use is particularly simple for investigations of Ī±-particle clustering (because Ī±-particle has JĻ=0+, which simplifies spin and parity assignments to observed cluster states), but they are also easily applicable to other types of clustering. Recent results on clustering in neutron-rich isotopes of beryllium, boron and carbon obtained measuring the 10B+10B reactions (at 50 and 72 MeV) are presented. The highly efficient and segmented detector systems used, built from 4 Double Sided Silicon Strip Detectors (DSSSD) allowed detection of double and multiple coincidences and, in that way, studies of states populated in transfer reactions, as well as their sequential decay