Constanta, Romania

Time filter

Source Type

Memet F.,Constantza Maritime University
European Journal of Science and Theology | Year: 2017

Nowadays, renewable energy is attractive for investors and also for society. Still, there are needed actions for the population awareness and environmental education. Internationally, religions started to have also an environmental mission, but maybe they should be involved in this issue more seriously. This study is presenting the results of a survey between the Romanian members of the Cross-Border Green Energy Cluster Romania-Bulgaria, investigating a potential link between beliefs of the members and environmental values. The questionnaire was structured on three sets of aspects: religious identity, relationship humans-environment and relationship self-involvement-environmental quality. Although the survey is at scale small-34 participants, it resulted that there are represented people from Orthodox and Muslim communities, sharing many times the same opinion on religious and environmental attitudes. © 2016, Ecozone, OAIMDD. All rights reserved.

Danisor A.,Constantza Maritime University
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

This paper proposes an analysis, especially in time domain, of the electrical noise existent on the power distribution lines. This study is important for the use of powerlines as a channel of information transmissions. This information may refer to analog signals and as well to digital signals. The main problem addressed in this paper consists in the characterization of the background noise and to establish his statistical proprieties. It is very important to know if the noise induced in the transmission channel is a stationary one, or even an ergodic one. The main parameters like the mean value, the mean square value were determined in this paper. The approximation of the probability density function of each statistical parameter was studied. The pulses induced in the transmission channel by the transient phenomena of the power electrical systems were considered deterministic signals and their contributions were not included in this study. © 2016 SPIE.

Danisor A.,Constantza Maritime University
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

In this paper we propose an analysis of the possibilities of spikes detection which appears on the power lines of electrical distribution. The importance of this problem consists in the possibility of surveillance at distance the regimes of power electrical motors. This regime was studied in an industrial network which supplies the power pumps necessary to assures a city water consumption. We consider the industrial electrical networks as a linear, time invariant and causal system which has a certain response to the electrical spikes, assimilates with Dirac impulses. For that reason the output signal represents the impulse response of the system. The main problem is to detect this signal and to establish the moments of its presence. To detect and extract the useful signal linear methods like fourier transform or Short Time Fourier Analysis are not very relevant. A more efficient method to detect the spikes presence consists in using quadratic detectors in timefrequency domain, like detectors based on Wigner-Ville transform or detectors based on Ambiguity Function. In this paper we tried to present the advantages of these last detectors. © 2016 SPIE.

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.

Scupi A.A.,Constantza Maritime University
IOP Conference Series: Materials Science and Engineering | Year: 2016

This paper is conceived on the idea that numerical programs using computer models of physical processes can be used both for scientific research and academic teaching to study different phenomena. Computational Fluid Dynamics (CFD) is used today on a large scale in research and academic institutions. CFD development is not limited to computer simulations of fluid flow phenomena. Analytical solutions for most fluid dynamics problems are already available for ideal or simplified situations for different situations. CFD is based on the Navier- Stokes (N-S) equations characterizing the flow of a single phase of any liquid. For multiphase flows the integrated N-S equations are complemented with equations of the Volume of Fluid Model (VOF) and with energy equations. Different turbulent models were used in the paper, each one of them with practical engineering applications: the flow around aerodynamic surfaces used as unconventional propulsion system, multiphase flows in a settling chamber and pneumatic transport systems, heat transfer in a heat exchanger etc. Some of them numerical results were validated by experimental results. Numerical programs are also used in academic institutions where certain aspects of various phenomena are presented to students (Bachelor, Master and PhD) for a better understanding of the phenomenon itself. © Published under licence by IOP Publishing Ltd.

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.

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.

Scurtu I.C.,Constantza Maritime University
IOP Conference Series: Materials Science and Engineering | Year: 2015

Manufacturing steps for a modern three - column semi-submersible structure are delivered using CFD/CAE software and actual Froude scaled model testing. The three- column offshore is part of the Wind Float Project already realized as prototype for wind energy extraction in water depths more than 40 meters, and the actual model will not consider the wind turbine. The model will have heave plates for a smaller heave motion in order to compare it with the case without heave plates. The heave plates will be part of the Froude scale model.. Using a smaller model will determine a smaller heave motion and this will affect predictions of the vertical movement of the three- column offshore structure in real sea. The Froude criterion is used for the time, speed and acceleration scale. The scale model is manufactured from steel and fiberglass and all parts are subjected to software analysis in order to get the smallest stress in connections inside the model. The model mass was restricted by scale dimensions and also the vertical position of centre gravity will be considered during the manufacturing and design process of the Froude scale offshore structure. All conditions must converge in model manufacturing and design in order to get the best results to compare with real sea states and heave motion data..

Tamas R.D.,Constantza Maritime University
IOP Conference Series: Materials Science and Engineering | Year: 2015

Numerical methods are widely used for modeling different physical phenomena in engineering, especially when an analytic approach is not possible. Time-domain or frequency- domain type variations are generally investigated, depending on the nature of the process under consideration. Some methods originate from mechanics, although most of their applications belong to other fields, such as electromagnetism. Conversely, other methods were firstly developed for electromagnetism, but their field of application was extended to other fields. This paper presents some results that we have obtained by using a general purpose method for solving linear equations, i.e., the method of moments (MoM), and a time-domain method derived for electromagnetism, i.e., the Transmission Line Matrix method (TLM)..

Ciucur V.,Constantza Maritime University
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Of three-phase alternating current electric machines, it brings into question which of them is more advantageous to be used in electrical energy storage system by pumping water. The two major categories among which are given dispute are synchronous and the asynchronous machine. To consider the synchronous machine with permanent magnet configuration because it brings advantages compared with conventional synchronous machine, first by removing the necessary additional excitation winding. From the point of view of loss of the two types of machines, the optimal adjustment of the magnetic flux density is obtained to minimize the copper loss by hysteresis and eddy currents. © 2015 SPIE.

Loading Constantza Maritime University collaborators
Loading Constantza Maritime University collaborators