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Rotaru A.,Technical University Gheorghe Asachi | Kolev C.,Todor Kableshkov University of Transport
Environmental Engineering and Management Journal | Year: 2010

Dobruja is a historical region shared by Romania and Bulgaria; it is located on the western Black Sea coast, around the Danube River. The main geological, seismic and geotechnical features, as well as natural hazards are presented in this review. A comparative analysis is made between the northern and southern parts of Dobruja. The region has witnessed various kinds of natural hazard over the past decades, and this paper describes the geotechnical characteristics and chronology of two of the more frequently occurring events, namely earthquakes and soil liquefaction. The structural relationships between the different rock formations in Romania and Bulgaria are analyzed, to show the extent to which they influence the dynamics of these events. The stability of foundations on liquefacted sand, silty clay and karsts on which installations such as wind generators, the nuclear power station and breakwaters are built have been examined in the light of the geoenvironmental risks. The similarity in structural, geotechnical and environmental relationships between Romania and Bulgaria engender common risks that could be properly addressed only through collaboration between scientists from both countries. Source

Marinov M.,Northumbria University | Agajere O.D.,Northumbria University | Bigotte M.,University of Lisbon | Proietti D.,University of Rome La Sapienza | Gerenska I.,Todor Kableshkov University of Transport
Transport Problems | Year: 2014

The main goal of this paper is to analyze customer satisfaction factors for Light Rail, identify a successful case and compare the level of service of this case with another system so that improvements in terms of price, time of journey and connectivity can be elaborated and suggested. The Docklands Light Railway (London, UK) has been identified as a successful case, which service levels have been compared to 'Metro Sul do Tejo, MST' (Almada, Portugal). As a result, a set of solutions to improve MST are proposed. Source

Hristova M.,Todor Kableshkov University of Transport
Cybernetics and Information Technologies | Year: 2016

The present article models and examines k∨n systems, in particular Triple modular redundancy (2∨3) and 3∨5. The aim of the study is to derive mathematical models, which are used for determining the impact of structural redundancy (the number of channels n and the threshold of the quorum function k) on the reliability of the system. The probability of failure-free operation p and the Mean Time Between Failures (MTBF) are used as reliability indicators. Source

Katev P.D.,Todor Kableshkov University of Transport
Proceedings of 9th International Conference, ELEKTRO 2012 | Year: 2012

Networks based on WiMAX (Worldwide Interoperability for Microwave Access) provide efficient packet radio interface. These networks enable high data transmission rates. WiMAX is the newest wireless broadband Internet technology based on IEEE 802.16 standard. Based on OFDM (Orthogonal Frequency Division Multiplexing), this system uses radio frequency range from 2 to 11 GHz. Calculation of path loss is very important, because it gives approximate values compared to any, obtained from real measurements. So it is helpful for initial deployment of WiMAX networks, providing an opportunity for cell planning. In this paper I discuss and compare following path loss models - Free Space Path Loss Model (FSPL Model), Hata-Okumura Extended Model (called also ECC-33 Model), Cost 231 Walfish-Ikegami Model and Stanford University Interim Model. In this paper I take the information on the location of buildings, the height of the transmitting antenna, receiving antenna and the others, consistent with conditions in Bulgaria. In each country, there are portions of the spectrum set aside for commercial purposes. In Europe and much of Asia, the 3.5 GHz spectrum range is used for broadband wireless, so I make calculations for 3.5 GHz. From calculations, that I made, can be concluded, that FSPL model, gives the lowest path loss, in all type of terrains - rural, suburban and rural areas. Model ECC-33 can predict path loss in urban and suburban areas, but it is unusable in rural areas. Also I can conclude, that model SUI, has approximately the same values of path loss with those, computed with FSPL model. My research shows that all four models for calculating the path loss are applicable to various areas, and we must compromise between coverage area and low interference of the transmitted signals, when we design WiMAX network. © 2012 IEEE. Source

Niculescu M.,Polytechnic University of Bucharest | Golgojan A.I.,Polytechnic University of Bucharest | Bednarz A.,Silesian University of Technology | Ivanova G.,Todor Kableshkov University of Transport | Maly T.,Brno University of Technology
Transport Problems | Year: 2014

This paper discusses smart railway infrastructure systems. The meaning of "smart" is described followed by a discussion on the benefits of the use of smart infrastructure. Some key components of smart infrastructure, few examples and case studies are presented. Our analysis suggests that the implementation of a smart system may well lead to energy savings of 25%, therefore smart systems should be implemented in larger scale. Source

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