Items

  • THE IMPORTANCE OF TRAINING IN LEADERSHIP IN MARITIME UNIVERSITIES

    RICARDO Rodríguez-Martos
    04/01/09
    2 citations
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    There is a lack of training in managing and leadership for future captains and officers. On the other side, companies pay more attention of a good management that of a good leadership. This article tries to underlines the importance of leadership and also deals with the question about the possibility to combine managing with leadership. Another important question to face is if man can be trained to be a leader and which concepts should be learned in this case. how a manager can also becomes a leader and how leadership can and should be learned. It will be also made a reference to the special aspect of multicultural crews and finally some ideas about the topics that should be teached for training in leadership
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  • A DINAMIC CURRENT UNIT FOR GETTING SYMMETRY OF THRE FAZE ELECTRICAL POWER SYSTEM

    PETKO Petkov; GEORGI Stoilov; MARIN Nedev; VLADIMIR Chikov; GINKO Angelov
    04/01/09
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    In the paper is subscribed a possibility of design and producing the electronic unit for dynamic current symmetrycity for three phase electrical distribution bar and system in cases of nonsymmetrical electrical loads. There is shown the investigated algorithm for control of the microprocessor’s unit. There is subscribed the results of experiment with the produced electronic microprocessor’s unit in real maintenance.
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  • COMPOSITE AND POLYMERIC MATERIALS USED IN NAVAL INDUSTRY

    Alexandra NIŢĂ
    04/01/09
    No citations
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    In the article [4] is published a mathematical model of optimization thermal stress-relief process which are conditioned by the plastic yield speed phenomenon. This new paper take in advance thermal stressrelief process and complete with overlapping ultrasonic stresses which is acting during cooling after welding process. In conformity with theory, Nevill and Brotzen [5] said that residual stresses are decreased because these overlapping stresses determined the altering of metallic yielding stress. In this article, using numerical method Runge-Kutta [1] is computed the overlapping ultrasonic stresses above welding residual stresses at OLC45 steel.
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  • AN ESTIMATING OF ELECTRICAL POWER FOR SUPPRESIOIN OF HARMONICS IN THE ELECTRICAL DISTRIBUTION BARS AND SYSTEMS WITH THE CURRENT IMPULSES INFLUENCE

    Marin NEDEV; Petko PETKOV ; VladimirCHIKOV; Ginko ANGELOV
    04/01/09
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    There made an estimating of electrical power, needed for suppresion the high harmonics in the electrical power distribution systems by the active filters with appling of current impulses. These metod is based on summerising of instantaneous current value and current impulses with the constant pulse width from the special function generator. The mentioned method is compared to other known solutions for decreasing of high harmonics. There is an estimating of possibility of applying in the autonomic electric power system.
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  • ANALYSIS OF THE MOST OCCURED AND TYPICAL FAILURES OF SLOW SPEED MARINE DIESEL ENGINES (SSMDE) RELATED TO CRANKSHAFT (CS).

    Julian MOSKOV
    04/01/09
    No citations
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    This report is a description of the case with main engine MAN 8L42MC, in which case, known by the experience, a failure related to turning round the crankshaft main journal from 1st to 7th movement is ascertained. Registering the problem is realized by means of the ship Mean Indicated Pressure (MIP) system. The deviations in the operation characteristics of the engine cylinders are indicated. Conclusions are reached and the procedure on restoring the engine normal operation mode is described with the purpose of diagnostics and avoiding similar failures in future.
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  • SOME ASPECTS REGARDING THE LNG OFFSHORE TERMINALS

    Feiza MEMET; Ender ASYALI
    04/01/09
    No citations
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    The important role of natural gas as a primary fuel in the energy industry led to the increase of its transportation on board the ships. This kind of transportation is made under the form of Liquefied Natural Gas (LNG), on board of special vessels, called LNG carriers which are equipped with cryogenic tanks. LNG carriers deliver it to terminals for storage and re-gasification, after which LNG is supplied to consumers from the LNG production plant, situated offshore. This paper presents the vaporization technology based on open-rack vaporizers (ORV), a modern technology for LNG terminals. Also, is discussed the environmental aspect connected with the construction of the terminal.
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  • THE OFF-SHORE PETROLEUM TERMINALS IMPACT ON THE MARINE ENVIRONMENT

    R. HANZU-PAZARA
    04/01/09
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    In the present days the energy request at the world level is growing-up. This increasing needs a necessity of more quantities of basic fuel, especially oil and coal. To satisfy the industrial and civil requirements and to cover the necessary quantities the transport field, mainly the maritime transport increase the transport capacity of their units. For the oil transport at sea, the tanker ship capacity has been expended from around 30,000 tones up to over half a million tones. These developments of maritime transport capacities impose to be developing new operational capacities. The operational capacities, the terminals, are difficult to be expend and improve when are placed in a limited space as harbors. This aspect conduct to necessity to create new terminals, placed outside of port area, in open sea, with possibility to receive and operate ships with tonnage more over the harbor terminals possibilities. This positioning in the open sea area has the risk of damaging the environment higher than port terminals. In the present paper will be presented some aspects of the impact on marine environment of the off-shore petroleum terminals.
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  • THE RAMSEY ALGORITHM

    ENG. Gabriela - Simona DUMITRESCU
    04/01/09
    No citations
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    This algorithm improved the best bounds known for approximating the independent set and graph coloring problems and prove that the approaches used to date to obtain such results can not be improved much further. I start with the Ramsey algorithm for finding independent sets in graphs, which is actually a schema of algorithms parameterized by the pivoting function applied, similar to the greedy algorithm. It has the property that its solution on any graph is at least as large as the one the corresponding greedy algorithm finds. The algorithm Ramsey is related to a classical problem in extremal graph theory [1].
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  • COMPUTATIONAL ULTRASONIC STRESS-RELIEF PROCESS

    Constantin DUMITRACHE; Corneliu COMANDAR; Mihaela BĂRHĂLESCU; Adrian SABĂU
    04/01/09
    No citations
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    In the article [4] is published a mathematical model of optimization thermal stress-relief process which are conditioned by the plastic yield speed phenomenon. This new paper take in advance thermal stressrelief process and complete with overlapping ultrasonic stresses which is acting during cooling after welding process. In conformity with theory, Nevill and Brotzen [5] said that residual stresses are decreased because these overlapping stresses determined the altering of metallic yielding stress. In this article, using numerical method Runge-Kutta [1] is computed the overlapping ultrasonic stresses above welding residual stresses at OLC45 steel.
    Full text Read PDF

  • SAINT VENANT EQUATIONS: AN ATTEMPT TO MODEL A TSUNAMI WAVE PROPAGATION

    DELEANU Dumitru
    04/01/09
    1 citation
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    By means of the homotopy analysis method, the solution of the unidimensional Saint Venant equations are obtained in this paper. These equations are a commonly accepted governing approximation for Tsunami wave propagation in the deep ocean as well as near-shore regions which include inundations. The dependent variables are the fluid heigh and the fluid velocity field. Analytical results agree well with the basic features of the tsunami waves. Numerical results are also presented and shown graphically.
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  • SOME APPLICATIONS OF THE FINITE ELEMENTS METHOD IN OBSERVATION OF THE MAGNETIC FIELD AND THE THERMAL PROCESSES IN 3 – PHASE INDUCTION MOTORS

    Bohos APRAHAMIAN
    04/01/09
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    The magnetic field of 3 – phase induction motors is studied using the finite elements method and the professional programming system ANSYS Emag. A model of induction motor, presenting a 20 degree sector of the motor, including two stator and two rotor grooves and two casing gills is studied due to the motor’s symmetry. Full pattern of the motor’s magnetic field is obtained in steady-state regime. All magnetic flux density vector flows are calculated and displayed too. Our study enables us to obtain the magnetic field of all induction motor’s parts in different steady-state working regimes. The transitional and stationary thermal processes in 3 – phase induction motors are studied using the finite elements method and the professional programming system ANSYS Emag too. Full pattern of the motor’s temperature field is obtained as well in transitional and in stationary temperature rate. All heat flows are calculated and displayed too. Our study enables us to obtain the overheat of all induction motor’s parts in different working regimes.
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  • STRUCTURAL ANALYSIS ON SUPERFICIAL LAYER WITH CARBIDE ELECTRODES

    Mihaela BARHALESCU; Cornel MUNTEANU; Constantin DUMITRACHE
    04/01/09
    No citations
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    The paper shows some theoretical and experimental aspects with reference to the superficial processing using electrical sparking. The tests objective was the superficial processing through sparking process on alloy and non alloy steel samples using a sinter carbide W and Ti electrodes type WCo8 and Ti15Co6. The paper shows metallographic analysis on sparking superficial layers. The analysis was made on NEOPHOT 32 (special microscope) and MC-2 and MC-6 (metallographic microscope). Optic metallographic analyses of sparking superficial layers obtained using “hard” carbide electrodes W and Ti sinterysed had as a result a white layer resistant at normal chemical reactive attack on sample surface. Under this layer a transition zone will form which is obvions at hardened proofs and under “hard” working condition.
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  • PROPOSAL OF INDICATORS OF SUSTANAIBILITY IN THE SECTOR OF THE MARITIME TRANSPORT

    Santiago ORDÁS; Jordi MESSEGUER
    4/1/2008
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    It is necessary to establish a system of indicators of the sustainable development in the maritime transport that allow to value the evolution of this sector for the ambience of the sustanaibility. The indicators have to reflect the triple dimension of the sustainable development: economic, social and environmental. These indicators of sustanaibility are hardware of evaluation that they help to construct a society with tuning with the environment. The following paper presents a series of indicators and his expression of calculation for the concrete case of the maritime transport. Some of these proposed indicators use the concept of unit of load of the ship, and in our case the concept of TEU is used, but there might be used the value of tons of load of the ship.
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  • MULTINATIONAL CREWS AND THEIR POSSIBLE INFLUENCE ON INCIDENTS WHICH ATTEMPT AGAINST ENVIRONMENT IN PORT

    Ricardo Rodríguez-Martos DAUER ; Joan Martín MALLOFRE ; Ricardo González BLANCO
    4/1/2008
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    In the last decades the number of multinational crews on board ships is increasing. It is a phenomenon that is closely related to Flags of Convenience and the employment of eventual crews of the 3rd World countries, through manning agencies. The problems regarding the join of different languages and cultures, and the questions about professional qualifications, induce us to presume that vessels with multinational crews are expected to suffer more incidents that can damage the environment, that others. In order to carry out with this investigation, it was made an analyse about the flags of the ships entered in Barcelona, Tarragona and Valencia in the last 3 years, to know the percentages of Spanish, foreign and convenience flags. The second step was to get a list of the incidents happened in those ports in the period between 1994 and 1999. From it we have try to establish a relation between risk of incidents and composition of crews. The third step was to collect opinions of ship agents. This paper cannot be used as determinant, but it let us take some first conclusions in order to warn the maritime community about the importance of composition of crews for safety and environment protection.
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  • MODERN ASPECTS OF MODELLING THE DYNAMIC BEHAVIOR OF HYDRAULIC POSITIVE DISPLACEMENT UNITS AND SYSTEMS PART I. GENERAL MODELLING APPROACH

    Peicho TOMOV
    4/1/2008
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    This report reviews in general results obtained by the author during his long scientific research experience in the field of hydraulic power drive systems and control systems with marine application. With modelling the static and dynamic of the operational processes, the thermal effects are observed by taking into account the working liquid condition. The non-isothermal approach is proved to be of great importance for the proper exploitation and maintenance of the system and its elements. The author submits a patentprotected hydraulic unit, which is experimentally examined and provides a theoretical base for the implementation of frequency controlled hydraulic drives. This kind of hydraulic drives is modern and perspective alternative of the classic hydraulic drives, which incorporate a variable displacement units.
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  • AN APPROACH TO THE DEVELOPMENT OF VIRTUAL DGPS NETWORKS

    MIROSLAV J. TSVETKOV; KOSTA I. IVANOV
    4/1/2008
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    This paper represents an approach for developing of a virtual reference systems network (Virtual DGPS Network) for the needs of the maritime navigation. The current status of DGPS coverage over the Mediterranean – Black Sea region is analyzed. The use of the data generated by the suggested model increases considerably the accuracy of GPS measurements, thus satisfying the requirements of the International Maritime Organization (IMO) and the requirements of the US Department of Defense and US Department of Transportation “2001 Federal Radionavigation Systems” (FRS).
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  • ENVIRONMENTAL, SOCIAL AND ECONOMIC ANALYSIS OF THE BIOGAS USE IN SPARK – IGNITION ENGINES

    Feiza MEMET
    4/1/2008
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    The biogas resulted from manure can be utilized in internal combustion engines in order to produce energy and to improve farms energy balance, in the famework of environmental pollution reduction. This issue has also a socioeconomic aspect because the discharging of rejects in the environment led to important concerns all over the world. The economic analysis should identify the best solution to burn the biogas flow in internal combustion engines, that is why are needed all incomes and expenses of the cogeneration plant.
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  • THE SUBMARINE CONTROL SIMULATOR “VALNA – K” – FEATURE DEVELOPMENT AND IMPROVEMENT DIRECTIONS

    Kancho KANEV; Evgeni MILANOV; Stefan ATANASOV
    4/1/2008
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    The use of simulators is a lasting trend in the process of training and maintaining the skills and habits of the crews of naval vessels. The contemporary computer technologies allow great possibilities for the development of simulators with a high degree of representation of processes and physical objects ( maneuvering ships, other processes in real time, ship systems, devices and complexes) [1], [2]. The Republic of Bulgaria has the design experience as well as the scientific and research units with well-proven achievements in the computer simulation and the development of maritime simulators. One of them is the “Valna-k” submarine control simulator.
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  • THERMAL STRESS-RELIEF PROCESS - NUMERICAL COMPUTATIONAL MODEL

    Constantin DUMITRACHE; Adrian SABĂU; Mihaela BĂRHĂLESCU
    4/1/2008
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    In the article [3] the authors propose a mathematical model of optimization thermal stress-relief process which are conditioned by the plastic yield speed phenomenon. These actual models take in advance experimental results but don’t reflect another practical phenomenon, the plastic yield speed is increasing in the vicinity of material yield point. In this paper is computed using numerical method Runge-Kutta [1] the time variation law σ(t) of thermal residual stresses at OLC45 steel.
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  • DISTORTIONAL SIMULATION IN THE STUDY OF FLOW THROUGH CIRCULAR CONDUITS

    Dumitru DINU; Monica STOIAN
    4/1/2008
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    In the paper we propose to use the FLUENT program to make a comparison between the results of application normal similitude and distortional similitude in the experiments regarding flow through circular conduits. First, we established the model law, taking into account the physical magnitudes which influence the analyzed phenomena. Afterwards we calculated the scales of these physical magnitudes for normal similitude (one geometrical scale) and distortional similitude (two geometrical scales). Using FLUENT we determined the values of the velocity in the conduit axis, putting the pressure parameters and the dimensions of the conduit according to the two cases of similitude. Finally, we compared the “experimental” results with theoretical results, calculated by application of scale of physical magnitudes.
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  • FACULTY MOTIVATION AND THE ROLE OF SOCIAL CAPITAL IN HIGHER EDUCATION

    Dimitar KANEV; Boyan MEDNIKAROV
    4/1/2008
    1 citation
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    The objective of this paper is to investigate the incentive structure of higher education and the role of social capital in it. In the beginning are proven the limited capabilities of the market mechanisms to stimulate the creation of high quality educational outcomes. After that are revealed the benefits from reciprocal relations in higher education institutions and development of a system of altruistic moral norms, which turn universities into communities centered on the cooperation, tolerance and solidarity values. Next the paper considers the role of social capital for increasing educational revenues and decreasing the transaction costs and personnel expenditures. Finally the question of social capital accumulation sources is analyzed. The latter are sought in the choice of the social enterprise as an organizational form and adopting those management structures that stimulate freedom and equality among the members of higher education institutions.
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  • APPROXIMATE SOLUTIONS TO AN APPROPRIATE MODEL EQUATION FOR FINITE-AMPLITUDE WAVES ON SHALLOW WATER SURFACES

    Dumitru DELEANU
    4/1/2008
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    Nonlinear phenomena play a crucial role in applied mathematics and physics. The results of solving nonlinear equations can guide us to know the described process deeply. Because it is difficult to obtain the exact solution for these problems, we can use one of the standard methods for solving nonlinear differential equations. In this paper, we apply the variational iteration method (VIM) for finding approximate solutions of the Korteweg-de Vries (KdV) equation, which describes the propagation of finite-amplitude waves in shallow water surfaces. The obtained solutions are compared with exact solution. The results are in good agreement, especially for higher iterations.
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  • AN APPLICATION OF NEURAL NETWORKS IN AUTOMATIC TARGET RECOGNITION AT SEA

    Chavdar ALEXANDROV; Christo PANCHEV
    4/1/2008
    1 citation
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    An approache to sea target recognition is examined in this paper. The automatic recognition of the target of observation is considered as detection of its tonnage class, approximate size and resulting maneuvering abilities. A neural network method is used to solve this problem. A number of experiments on real targets are described. Possibilities for application of Automatic Target Recognition (ATR) in sea navigation are proposed based on these experimental findings.
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  • SOME APPLICATIONS OF NANODIMENSIONAL FUNCTIONAL LAYERS IN SHIP ELECTRONICS

    Bohos APRAHAMIAN
    4/1/2008
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    Nanostructured materials have a number of desirable thermal, electromagnetic and mechanical properties and can play a significant role in improving key parameters of the ship electronic equipment. Our recent work consist the obtaining of resistive elements, formed upon electroinsulated plates of alumina ceramics with nanodimensional conductive layers. Different layer compositions are experimented and the change of the electrical resistance due to the temperature rate is studied. The elements are applied as sensors in electronic bridge circuit for positive temperature measuring. In recent years, nanoscaled magnetic materials have received much attention too, due to the fundamental interest in the unique magnetic property different from that in the bulk phase and to their promising applications in technology such as in the high-density magnetic storage. The magnetic properties are usually dictated by the size, dimension, shape, structure, morphology of the constituent phases, along with the type and strength of magnetic coupling between them. The magnetic metals, including Fe, Co, Ni, and their related alloys in low dimensional form, are one of the most important subjects to study. Nanostructured materials can improve key antenna parameters like radiation-efficiency, directivity and mechanical robustness. Electromagnetic absorption properties can be controlled by changing the particle size distribution in nano-materials and application-specific, tailored materials can be produced.
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  • COATINGS FOR CORROSION PROTECTIONS OF STEEL CARBON OBTAINED THROUGH IMPULSE ELECTRICAL DISCHARGES

    Mihaela BARHALESCU; Constantin DUMITRACHE
    4/1/2008
    Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced; technologies for MET; Climate changes
    The work entitled “Coatings for corrosion protections of steel carbon obtained through impulse electrical discharges” presents the research done by the authors in regards with obtaining some superficial metallic layers, on parts made of carbon steel OL 37 brand, with the help of some electrodes from a corrosion resistant material (Cu). The corrosion resistance of the experimental attained layers was obtained with the polarization curves method. The superficial layers subjected to electrochemical corrosion where analyzed through optical metallographic microscopy, using the computers QX3 Intel Play microscope. The investigations made reflected an improvement of the superficial layers quality in regard to thermodynamics corrosion probability.
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