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Maximum daily rainfall analysis at selected meteorological stations in the upper Lusatian Neisse River basin

Wdowikowski M., Kaźmierczak B., Ledvinka O.

Meteorology Hydrology and Water Management. Research and Operational Applications

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2016

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Vol. 4, Iss. 1

53--63

EN

The scope of this study was to assess the usefulness of top probability distributions to describe maximum rainfall data in the Lusatian Neisse River basin, based on eight IMWM-NRI meteorological stations. The research material was composed of 50-year precipitation series of daily totals from 1961 to 2010. Misssing measurement data were estimated using a weighted average method. Homogeneity for refilled data were investigated by precipitation double aggregation curve. Correlation between the measurement data varied from 96 to 99% and did not indicate a violation of the homogeneity of rainfall data series. Variability of recorded daily precipitation maxima were studied by linear regression and non-parametric Mann-Kendall tests. Long-term period changes at maximum rainfalls for four stations remained statistically insignificant, and for the other four were significant, although the structure of maximums was relatively similar. To describe the measured data, there were used the Fréchet, Gamma, Generalized Exponential Distribution (GED), Gumbel, Log-normal and Weibull distributions. Particular distribution parameters were estimated using the maximum likelihood method. The conformity of the analyzed theoretical distributions with measured data was inspected using the Schwarz Bayesian information criterion (BIC) and also by the relative residual mean square error (RRMSE). Among others, the Gamma, GED, and Weibull distributions fulfilled the compliance criterion for each meteorological station respectively. The BIC criterion indicated GED as the best; however differences were minor between GED on the one hand and the Gamma and Weibull distributions on the other. After conducting the RRMSE analysis it was found that, in comparison to the other distributions, GED best describes the measured maximum rainfall data.

2

Wykorzystanie rozkładu GED do modelowania rozkładu stóp zwrotu spółek sektora transportowego

Purczyński J., Czyżycki R.

Logistyka

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2014

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nr 6

8996--9005

PL

W artykule przedstawiono możliwość wykorzystania rozkładu GED, do modelowania dziennych stóp zwrotu wybranych spółek sektora transportowego, notowanych na Warszawskiej Giełdzie Papierów Wartościowych. W badaniach wykorzystano zarówno klasyczną, jak i logarytmiczną stopę zwrotu oraz przyjęto roczny, półroczny oraz kwartalny okres estymacji parametrów omawianego rozkładu.

EN

The paper discusses the possibility of applying GED distribution in modeling daily rates of return on selected transportation sector companies listed on the Warsaw Stock Exchange. In the research both classical and logarithmic return rates were applied. Furthermore, yearly, half-yearly and quarterly periods of parameter estimation of the distribution in question were considered.

3

Influence of the User Importance Measure on the Group Evolution Discovery

Saganowski S., Bródka P., Kazienko P.

Foundations of Computing and Decision Sciences

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2012

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Vol. 37, No. 4

295--305

EN

One of the most interesting topics in social network science are social groups, i.e. their extraction, dynamics and evolution. One year ago the method for group evolution discovery (GED) was introduced. The GED method during extraction process takes into account both the group members quality and quantity. The quality is reflected by user importance measure. In this paper the influence of different user importance measures on the results of the GED method is examined and presented. The results indicate that using global measures like social position (page rank) allows to achieve more precise results than using local measures like degree centrality or no measure at all.