Bratislava, Slovakia
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Sipkova V.,Slovak Academy of Sciences | Hluchy L.,Slovak Academy of Sciences | Dobrucky M.,Slovak Academy of Sciences | Bartok J.,Microstep MIS | Nguyen B.M.,Hanoi University of Science and Technology
Proceedings of the 2016 IEEE 12th International Conference on e-Science, e-Science 2016 | Year: 2016

The Weather Research and Forecasting (WRF) model represents a mesoscale numerical weather prediction system designed for both the atmospheric research and operational forecasting use. WRF offers several computationally efficient platforms while providing serial and parallel models running with or without multi-threading. The main goal of the work described in this paper was to develop management software tools facilitating the execution of WRF simulations on High Performance Computing (HPC) infrastructures. The management tools enable easily to carry out the complex simulation process, representing a workflow of central jobs, i.e. preprocessing, modeling and post-processing, which are running primarily on our local HPC cluster with the possibility to exploit also the computational power of the European Grid infrastructure. The second objective of this work was the investigation of parallel MPI and hybrid parallel MPI+OpenMP WRF models using the created tools to run simulations. The aim was to find out the most suitable combination of hardware and software configuration setting for the realization of the WRF simulation process with the given input scenario. Performance results of real simulation processes running on various hardware configurations of the cluster are presented. © 2016 IEEE.

Povinec P.P.,Comenius University | Gera M.,Comenius University | Holy K.,Comenius University | Hirose K.,Sophia University | And 7 more authors.
Applied Radiation and Isotopes | Year: 2013

Large quantities of radionuclides were released in March-April 2011 during the accident of the Fukushima Dai-ichi Nuclear Power Plant to the atmosphere and the ocean. Atmospheric and marine modeling has been carried out to predict the dispersion of radionuclides worldwide, to compare the predicted and measured radionuclide concentrations, and to assess the impact of the accident on the environment. Atmospheric Lagrangian dispersion modeling was used to simulate the dispersion of 137Cs over America and Europe. Global ocean circulation model was applied to predict the dispersion of 137Cs in the Pacific Ocean. The measured and simulated 137Cs concentrations in atmospheric aerosols and in seawater are compared with global fallout and the Chernobyl accident, which represent the main sources of the pre-Fukushima radionuclide background in the environment. The radionuclide concentrations in the atmosphere have been negligible when compared with the Chernobyl levels. The maximum 137Cs concentration in surface waters of the open Pacific Ocean will be around 20Bq/m3. The plume will reach the US coast 4-5y after the accident, however, the levels will be below 3Bq/m3. All the North Pacific Ocean will be labeled with Fukushima 137Cs 10y after the accident with concentration bellow 1Bq/m3. © 2013 Elsevier Ltd.

Smetanova I.,Slovak Academy of Sciences | Holy K.,Comenius University | Zelinka J.,State Nature Conservancy of the Slovak Republic | Omelka J.,MicroStep MIS
Radiation Protection Dosimetry | Year: 2014

Continual monitoring of radon activity concentration was performed in two caves: Domica and Važecká. Radon in the air of the Domica cave was monitored from June 2010 to July 2011. Radon research in the Važecká cave started in June 2012 and it is still being carried out. Radon concentration in cave atmosphere exhibited seasonal, short-term and daily variations. Daily average of radon in Domica varied from 0.5 to 2.7 kBq m-3. Seasonal trend was characterised by the highest concentration in September and the lowest from February to March. Radon concentration in the Važecká cave was significantly higher, and the daily average ranged from 1.0 to 5.3 kBq m-3. The highest values were registered from June to September and in January. The seasonal and daily variations of 222Rn activity concentration in the atmosphere of both caves are assumed to be associated with the atmospheric temperature. No effect of atmospheric pressure on radon short-term variation was found. © The Author 2014. Published by Oxford University Press. All rights reserved.

Bartokova I.,Comenius University | Kl'ocova M.,Microstep MIS | Bartok J.,Microstep MIS
Contributions to Geophysics and Geodesy | Year: 2014

Recently we can see the trend of introducing a new instrumentation and automatization in the field of information and monitoring systems for the meteorology, hydrology and crisis centers. Nowadays a great number of sensors are used in projects in many countries of various climates. Therefore it is crucial to deeply understand how the change of sensor types will affect the accuracy of measurements and how is accuracy of individual sensor type affected by different weather conditions. We analyzed several screen/shields and rain gauges at the premises of faculty of Meteorology and Climatology of FMFI UK. On the basis of our results we can recommend as a most accurate and not depending on weather condition artificially ventilated screen although it is the most expensive. Our second choice would be a large naturally ventilated shield. In case of Stevenson screens we would recommend painting it with a high gloss coating. Our last choice would be a small naturally ventilated screen because of its high sensitivity to the global radiation. Our first choice of the participating rain gauges would be the weighing rain gauge because of its best results in both cases, of rainfalls up to 2 mm and also over 2 mm. The tipping bucket rain gauge gave also agreeable result in both cases. The optical sensor gave very good results in rainfalls over 2 mm but it is unsuitable for rainfalls up to 2 mm. The radar sensor is also completely unsuitable for low intensity rainfalls and his performance for rainfalls over 2 mm was just average. © by Ivana Bartoková 2014.

Bartokova I.,Microstep MIS | Bott A.,University of Bonn | Bartok J.,Microstep MIS | Gera M.,Comenius University
Boundary-Layer Meteorology | Year: 2015

A new model for nowcasting fog events in the coastal desert area of Dubai is presented, based on a machine-learning algorithm—decision-tree induction. In the investigated region high frequency observations from automatic weather stations were utilized as a database for the analysis of useful patterns. The induced decision trees yield for the first six forecasting hours increased prediction skill when compared to the coupled Weather Research and Forecasting (WRF) model and the PAFOG fog model (Bartok et al., Boundary-Layer Meteorol 145:485–506, 2012). The decision tree results were further improved by integrating the output of the coupled numerical fog forecasting models in the training database of the decision tree. With this treatment, the statistical quality measures, i.e. the probability of detection, the false alarm ratio, and the Gilbert’s skill score, achieved values of 0.88, 0.19, and 0.69, respectively. From these results we conclude that the best fog forecast in the Dubai region is obtained by applying for the first six forecast hours the newly-developed machine-learning algorithm, while for forecast times exceeding 6 h the coupled numerical models are the best choice. © 2015 Springer Science+Business Media Dordrecht

Bartok J.,Microstep MIS | Bott A.,University of Bonn | Gera M.,Comenius University
Boundary-Layer Meteorology | Year: 2012

Modern weather prediction models use relatively high grid resolutions as well as sophisticated parametrization schemes for microphysical and other subgrid-scale atmospheric processes. Nonetheless, with these models it remains a difficult task to perform successful numerical fog forecasts since many factors controlling a particular fog event are not yet sufficiently simulated. Here we describe our efforts to create a mechanism that produces successful predictions of fog in the territory located on the north coast of the Arabian Peninsula. Our approach consists in the coupling of the one-dimensional PAFOG fog model with the three-dimensional WRF 3. 0 (Weather Research and Forecast) modelling system. The proposed method allows us to construct an efficient operative road traffic warning system for the occurrence of fog in the investigated region. In total 84 historical situations were studied during the period 2008-2009. Moreover, results of operative day-by-day fog forecasting during January and February 2010 are presented. For the investigated arid and hot climate region the land-sea breeze circulation seems to be the major factor affecting the diurnal variations of the meteorological conditions, frequently resulting in the formation of fog. © 2012 Springer Science+Business Media B.V.

Mihailovic D.T.,University of Novi Sad | Krmar M.,University of Novi Sad | Mimic G.,University of Novi Sad | Nikolic-Doric E.,University of Novi Sad | And 4 more authors.
Radiation Physics and Chemistry | Year: 2015

In this paper we have analyzed 222Rn concentration variation in Domica cave (Slovakia) for the period June 2010-June 2011. In that sense we have applied a complexity analysis on 222Rn concentration time series. We have considered possible existence of a periodical component in the variation of 222Rn concentration and some environmental parameters, as well as possible correlation between them. In addition we have offered novel complexity measures based on the Kolmogorov complexity (KC), i.e. the Kolmogorov complexity spectrum, its highest value (KCM) and the integral Kolmogorov complexity (KCI). These measures have been applied on 222Rn concentration time series: (i) to establish the dependence of 222Rn concentration on cave environmental parameters (wind speed inside the cave, external wind speed, air temperature, atmospheric pressure and CO2 concentration) and (ii) to see whether influence of some parameters make the distribution of measured quantity less or more stochastic. © 2014 Elsevier Ltd.

Macica J.,MicroStep MIS | Farkas P.,Slovak University of Technology in Bratislava | Krile S.,University of Dubrovnik
Radioengineering | Year: 2010

Computational technique for lower bound on Two-dimensional Diamond-1 constrained channel capacity is presented in this paper. It is basically an amalgamation of Matrix Fractal Grow Method (MFGM) and a new Matrix Fractal Reduction Method both applicable to state transition matrices of the corresponding constrained channels and Rayleigh Quotient Iteration method. Also other programming tricks are presented which improve its implementation. Estimation of lower bound values on the mentioned capacity is made using it. The results are in good alignment with known exact results, which is a verification of the new method. The method could be generalized for other constraints which are restricted only on one neighbor symbol in 2D constrained channel such as for example Square-1 and Hexagonal-1.

Peter K.,Slovak Academy of Sciences | Ladislav H.,Slovak Academy of Sciences | Juraj B.,Microstep MIS
SISY 2013 - IEEE 11th International Symposium on Intelligent Systems and Informatics, Proceedings | Year: 2013

Chemistry and nuclear physics represent one of possible options of large area for practical data mining applications. Radio-active nuclides are related with many sectors, such as medicine or industry. Successful detection and identification of radio-nuclides allows the realization of specific safety precaution and then increasing of security level in nuclear power plants, or medicine institutes. Data obtained by radio spectroscopy method reach high level of relevancy. Thus these data are suitable for using data mining methods, because the presented problem corresponds with classification task. Two radio-nuclides identification methods were presented in this paper; the second method is designed specially for this purpose. © 2013 IEEE.

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