Renko T.,Meteorological and Hydrological Service |
Kuzmic J.,Meteorological and Hydrological Service |
Soljan V.,Croatia Control Ltd. |
Mahovic N.S.,Meteorological and Hydrological Service
Natural Hazards | Year: 2016
One step toward improving our understanding of all the possible factors and environmental features that are related to waterspout formation is to establish continuous data collection and to provide a preliminary climatology of waterspouts in a region. A waterspout survey was launched on the official Web site of the Croatian Meteorological and Hydrological Service during late spring 2011. This survey helped create an extensive waterspout database, which recorded a total of 359 waterspout events from 2001 to 2013. Because most reports regarding waterspouts were obtained from unofficial sources, we underline the need for new ways to observe relatively short, rare and spatially limited weather events such as waterspouts. The analysis of the collected data in this work includes the spatial and temporal distribution of the waterspout events per year, season, month and time of day. “Non-thunderstorm” and “thunderstorm” waterspouts were separated, and the absolute frequencies of five synoptic types that were relevant to waterspout development are shown. Finally, the thermodynamic environment was analyzed with the help of radio-sounding data. The results show that waterspout events are equally distributed along the eastern part of the Adriatic coast. However, an evident connection exists between the number of spotted events and the locations of more densely populated areas, i.e., big towns or tourist destinations. Waterspouts are more frequent during the summer months, especially during August, and 51.5 % of the recorded events were related to thunderstorms. Most of them were spotted during the day, whereas only two were spotted during the night; waterspouts developed more often during the morning hours. The synoptic environment dominated by a southwesterly flow has proven to be the most supportive for the development of waterspouts. © 2016 Springer Science+Business Media Dordrecht
Poles D.,Croatia Control Ltd.
IEEE EuroCon 2013 | Year: 2013
This paper proposes and analyzes the one-level and the two-level scheduling approach. The one-level scheduling uses one scheduling policy for scheduling all tasks, whereas the two-level scheduling uses one scheduling policy for the scheduling of high priority tasks and other for the scheduling of low priority tasks. Both scheduling approaches use Earliest Deadline First and Rate Monotonic scheduling algorithms, the two-level scheduling only for scheduling of higher priority tasks. The focus of both approaches is the scheduling of the Imprecise Computation Model tasks. The Imprecise Computation Model trades off the quality of computations with the timeliness. It decomposes each task into a mandatory part and an optional part. Only the mandatory part is required to complete by task's deadline. The scheduling of Imprecise Computation Model tasks that minimizes the total-weighted error is considered. The one-level scheduling is based on an extension of mandatory parts that minimizes the total-weighted error. In order to minimize the total-weighted error the two-level scheduling uses modified Algorithm WNTU by the low level scheduler. The analysis of both approaches is provided including complexity, response time analysis and simulations. Based on the theoretical foundations and the results of simulations the use of one-level and two-level scheduling is recommended under certain assumptions. Single preemptive model is assumed. © 2013 IEEE.
Mihetec T.,University of Zagreb |
Steiner S.,University of Zagreb |
Jaksic Z.,Croatia Control Ltd.
Transport Problems | Year: 2012
This paper evaluates feasibility of the new Air Traffic Management (ATM) organisation in Functional Airspace Block Central Europe (FAB CE) and specifies the implementation scenarios that are proposed by Central European Air Traffic Services Coordination Group (CEATS CG). The paper elaborates elements of required Functional Airspace Block Central Europe implementation and identifies and assesses the implementation blockers. Provision of air navigation services in European Civil Aviation Conference (ECAC) area is diversely regulated and highly fragmented.