73 research outputs found

    Comparative assessment of methods for forecasting river runoff with different conditions of organization

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    The article presents the results of comparative analysis of application of traditional statistical methods and non linear multilayer neural networks for processing multi year data of the river runoff with the aim of its forecasting. The obtained in the work optimal parameters for learning predictive neural networks are recommended ed for learning transformation and forecast of river runoff in the situation of permenant anthropogenic influence on basinyesБелгородский государственный университе

    Evaluation of siltation of rivers with intensive economic development of watersheds

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    In regions with a high degree of agricultural development with an active development of erosion processes and the critical level of degradation of the river network to which the Middle-Russian Upland belongs, the evaluation of sedimentation for various combinations of natural and economic conditions becomes an immediate proble

    Systematics of Inclusive Photon Production in 158 AGeV Pb Induced Reactions on Ni, Nb, and Pb Targets

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    The multiplicity of inclusive photons has been measured on an event-by-event basis for 158 AGeV Pb induced reactions on Ni, Nb, and Pb targets. The systematics of the pseudorapidity densities at midrapidity (rho_max) and the width of the pseudorapidity distributions have been studied for varying centralities for these collisions. A power law fit to the photon yield as a function of the number of participating nucleons gives a value of 1.13+-0.03 for the exponent. The mean transverse momentum, , of photons determined from the ratio of the measured electromagnetic transverse energy and photon multiplicity, remains almost constant with increasing rho_max. Results are compared with model predictions.Comment: 16 pages including 4 figure

    Scaling of Particle and Transverse Energy Production in 208Pb+208Pb collisions at 158 A GeV

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    Transverse energy, charged particle pseudorapidity distributions and photon transverse momentum spectra have been studied as a function of the number of participants (N_{part}) and the number of binary nucleon-nucleon collisions (N_{coll}) in 158 A GeV Pb+Pb collisions over a wide impact parameter range. A scaling of the transverse energy pseudorapidity density at midrapidity as N_{part}^{1.08 \pm 0.06} and N_{coll}^{0.83 \pm 0.05} is observed. For the charged particle pseudorapidity density at midrapidity we find a scaling as N_{part}^{1.07 \pm 0.04} and N_{coll}^{0.82 \pm 0.03}. This faster than linear scaling with N_{part} indicates a violation of the naive Wounded Nucleon Model.Comment: 13 pages, 16 figures, submitted to European Physical Journal C (revised results for scaling exponents

    Low background detector with enriched 116CdWO4 crystal scintillators to search for double beta decay of 116Cd

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    A cadmium tungstate crystal boule enriched in 116^{116}Cd to 82% with mass of 1868 g was grown by the low-thermal-gradient Czochralski technique. The isotopic composition of cadmium and the trace contamination of the crystal were estimated by High Resolution Inductively Coupled Plasma Mass-Spectrometry. The crystal scintillators produced from the boule were subjected to characterization that included measurements of transmittance and energy resolution. A low background scintillation detector with two 116^{116}CdWO4_4 crystal scintillators (586 g and 589 g) was developed. The detector was running over 1727 h deep underground at the Gran Sasso National Laboratories of the INFN (Italy), which allowed to estimate the radioactive contamination of the enriched crystal scintillators. The radiopurity of a third 116^{116}CdWO4_4 sample (326 g) was tested with the help of ultra-low background high purity germanium γ\gamma detector. Monte Carlo simulations of double β\beta processes in 116^{116}Cd were used to estimate the sensitivity of an experiment to search for double β\beta decay of 116^{116}Cd.Comment: 24 pages, 13 figures, 3 tables, accepted for publication on Journal of Instrumentatio

    The bright Type IIP SN 2009bw, showing signs of interaction

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    We present photometry and spectroscopy of the type IIP supernova 2009bw in UGC 2890 from few days after the outburst to 241 days. The light curve of SN 2009bw during the photospheric phase is similar to that of normal SNe IIP but with brighter peak and plateau (Mmax R = -17.82 mag, Mplateau R = -17.37 mag). The luminosity drop from the photospheric to the nebular phase is one of the fastest ever observed, ~2.2 mag in about 13 days. The radioactive tail of the bolometric light curve indicates that the amount of ejected 56 Ni is \approx 0.022 M\odot. The photospheric spectra reveal high velocity lines of H{\alpha} and H{\beta} until about 105 days after the shock breakout, suggesting a possible early interaction between the SN ejecta and pre-existent circumstellar material, and the presence of CNO elements. By modeling the bolometric light curve, ejecta expansion velocity and photospheric temperature, we estimate a total ejected mass of 8-12M\odot, a kinetic energy of ~0.3 foe and an initial radius of ~ 3.6 - 7 \times 10^13 cm.Comment: Accepted for publication in MNRAS, 19 pages, 13 figures, 9 table

    Freeze-Out Parameters in Central 158AGeV Pb+Pb Collisions

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    Neutral pion production in central 158AGeV Pb+Pb collisions has been studied in the WA98 experiment at the CERN SPS. The pi0 transverse mass spectrum has been analyzed in terms of a thermal model with hydrodynamic expansion. The high accuracy and large kinematic coverage of the measurement allow to limit previously noted ambiguities in the extracted freeze-out parameters. The results are shown to be sensitive to the shape of the velocity distribution at freeze-out.Comment: 5 pages including 3 figures, small changes due to review process, accepted for publication in Phys.Rev.Let

    Direct Photon Production in 158 AGeV Pb+Pb Collisions

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    A measurement of direct photon production in Pb+Pb collisions at 158 AGeV has been carried out in the CERN WA98 experiment. The invariant yield of direct photons in central collisions is extracted as a function of transverse momentum in the interval 0.5 < pT < 4 GeV/c. A significant direct photon signal, compared to statistical and systematical errors, is seen at pT > 1.5 GeV/c. The results constitute the first observation of direct photons in ultrarelativistic heavy-ion collisions which could be significant for diagnosis of quark gluon plasma formation.Comment: Talk presented at Nucleus-Nucleus 2000, Strasbourg, Franc

    Comparative assessment of methods for forecasting river runoff with different conditions of organization

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    yesThe article presents the results of comparative analysis of application of traditional statistical methods and non linear multilayer neural networks for processing multi year data of the river runoff with the aim of its forecasting. The obtained in the work optimal parameters for learning predictive neural networks are recommended ed for learning transformation and forecast of river runoff in the situation of permenant anthropogenic influence on basinБелгородский государственный университе
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