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Constanta, Romania

Tamas R.D.,Constantza Maritime University
2016 International Workshop on Antenna Technology, iWAT 2016 | Year: 2016

Previously, the author has described a method for measuring the antenna gain in non-anechoic sites. The effects of reflection and diffraction on the neighboring objects can be dramatically reduced by averaging, over a set of distances, a normalized transfer function of the system consisting of the antenna under test and the measuring antenna. The method was successfully tested on dipole type, ultra-wide band antennas. This paper, presents further results on measuring narrow band, monopole antennas. It comes out that averaging does not remove the effect of the diffraction on scatterers close to the radiating element, such as the edges of the antenna ground plane; conversely, it reasonably reduces the effects of scatterers placed at several wavelengths away from the antenna under test. © 2016 IEEE. Source

Croitoru A.-E.,Babes - Bolyai University | Chiotoroiu B.-C.,Constantza Maritime University | Ivanova Todorova V.,Bulgarian Academy of Science | Torica V.,Regional Weather Forecasting Center Constanta
Global and Planetary Change | Year: 2013

Changes in daily extreme precipitations have been identified in many studies conducted at local, regional or global scales. For the Black Sea region, only little research on this issue was done. In this paper, the Black Sea Western coast covering Bulgarian, Romanian and partially Ukrainian coastlines was considered. The present study is focused on the analysis of the trends in daily extreme precipitations indices at a regional scale over 48. yrs (1961-2008). Data sets of daily precipitation recorded in 13 weather stations were analyzed. Among them, eight are located in Bulgaria, four in Romania and one in Ukraine. The main goal was to find changes in extreme daily rainfall using a set of 11 indices adopted from the core indices developed by ETCCDMI with appropriate modifications to suit to the studied area. The indices series and trends were generated using RClimDex software. The results seem integrated to the global and European continental scales findings: increasing trends are dominant for almost all indices; most of the calculated slopes are statistically insignificant; the distribution of positive and negative slopes in the area is extremely irregular and the changes in Northern stations are more significant compared to those calculated for Southern stations. © 2013 Elsevier B.V. Source

Constantin S.L.,Constantza Maritime University
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

This study presents numerical and experimental results concerning a test impeller of a centrifugal pump. From the experimental point of view, the cavitation was visualized at different Inlet Pressure values. Image processing and statistical treatment of the photographs taken at given impeller position allowed to quantify the attached and cloud cavitation extent. A numerical model of 3D cavitating flows, based on the CFD code Fluent 6.1, has been developed to predict the cavitation behavior in the presented model which is considering the entire pump, the impeller and also the casing of the pump, with all its complex geometry and flow parameters. Non-cavitating and cavitating conditions were investigated. Calculations were found to be in good agreement with experimental measurements and visualisations. Experimental and numerical results concerning the pump parameters were investigated. The overall conclusion is the obvious knowledge that the Net Positive Suction Head (NPSH) is indeed affecting the cavitation condition in the centrifugal pumps, having direct impact on the magnitude of static pressures in various locations inside the pump, but is not altering too much the velocities distributions of fluid. © 2012 SPIE. Source

Ciucur V.-V.,Constantza Maritime University
Electronics and Electrical Engineering - Proceedings of the Asia-Pacific Conference on Electronics and Electrical Engineering, EEEC 2014 | Year: 2015

The control system for the speed position of a DC motor, generally can be controlled by a microprocessor, or microcomputer, all these components which can determine the values for speed for each movement and passes. The system can contain a D/A converter. In order to obtain signals which can then be processed by a converter an optical encoder can be used, mounted on the shaft of a DC motor. © 2015 Taylor & Francis Group, London. Source

Liviu-Constantin S.,Constantza Maritime University
2010 The 2nd International Conference on Computer and Automation Engineering, ICCAE 2010 | Year: 2010

This paper represents a step forward toward the introduction of engineering advanced research methods for the study of dynamic behavior of marine propulsion systems. The large dimensions of this work and its both theoretical and research material developed in it via numerical simulation are witnessing of the author effort for an exhaustive treatment of the proposed theme. ©2010 IEEE. Source

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