Items · Journal of Marine Technology and Environment

OCEANOGRAPHIC ENVIRONMENTAL ASSESSMENT USING UNDERWATER GLIDERS

LaurențIu-Florin CONSTANTINOIU; Luis QUARESMA; Eugen RUSU

10/1/2022

DOI: 10.53464/JMTE.02.2022.02

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

REP(MUS) 21 is an annual exercise jointly organised by the Portuguese Navy, the University of Porto, NATO’s Centre for Maritime Research and Experimentation (CMRE) and the NATO Maritime Unmanned Systems Initiative. The exercise gives Allies and NATO partners a chance to field and evaluate new maritime technologies. A Rapid Environmental Assessment warfare group was formed using Maritime Unmanned Systems to perform an environmental assessment of this area, by collecting data from the upper ocean region (0- 200 m.), sea surface, littoral shallow waters, and river estuary. Underwater Gliders were used in the REPMUS21 exercise, brought by several partners, to conduct environmental observations from the underwater domain of the exercise’s Joint Operations Area (JOA). This paper focuses on the use of SeaExplorer underwater gliders to collect oceanographic data during the exercise, and the operational impact of using this knowledge to compile the Recognized Environmental Picture of the exercise area.

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FUTURE DEVELOPMENTS ON CONTAINER SHIP DESIGN

Milis Nilgun CALIBULA; Constantin MILITARU

10/1/2022

DOI:10.53464/JMTE.02.2022.01

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

In this paper shows analysis on container ship design. Today, containers on vessel contain a wide range of different goods from consumer goods as shoes and electronic devices to chemicalsand other raw materials. Nevertheless, a container vessel is a cargo ship that carries all of its load in truck-size intermodal containers, in a technique called containerization. This article briefly discusses the scheduling of current conbtainer ship. Threfore, the manuscript major are: design of cargo ship, analyzed two model from vessel, types of container ships, etc. The design of a cargo ship was done with the NX software from Siemens. Finally, the recent trends in container vessel programming and the shortcomings of existing models are discussed.

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ASSESSMENT OF THE PERFORMANCE A VAPOUR COMPORESSION. REFRIGERATION CYCLE WORKING WITH AMMONIA

Ionela TICU; Elena GOGU

DOI: 10.53464/JMTE.

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

This paper is a part of the efforts done in order to analyse the performance of vapour compression refrigeration cycles. These technologies are used with a high rate in marine refrigeration and are responsible for important amounts of energy consumptions. The obtained results are indicating the fact that the performance of the cycle is decreased when increasing the condensation temperature and keeping constant the evaporation temperature. Gains in the performance are obtained when degrees of superheating and sub cooling are increased, resulting that the cycle with superheating and sub cooling is superior to the one without these two processes. Ammonia or (R717) is a refrigerant often used on board the ships due to its very good thermodynamic properties. Moreover, the concern regarding the environment and the fact that ammonia is a natural refrigerant, offers to this refrigerant the chance to be adopted in the future plants, on board of new ships. The performance of an ammonia based cycle is discussed in terms of coefficient of performance (COP) and exergy efficiency, the theory of the first and second laws of thermodynamics being fundamental.

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PRODUCIBILITY OF FUNCTIONALLY GRADED AlB2/Al COMPOSITE MATERIAL

ÖMer SAVAŞ ; Canberk KARATAŞ

4/1/2022

DOI: 10.53464/JMTE

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

This study is intended to investigate producibility of functionally graded AlB2/Al composites which are used in the manufacture of ship machinery parts. AlB2 particles have been spontaneously formed in liquid matrix as reinforcement. A semi-solid composite (Al(l) - AlB2(s)) prepared at 850°C was solidified under a centrifugal force to grade functionally. The properties of composite materials such as hardness and microstructure have been examined. This research provided the following findings, AlB2 particles can be successfully synthesized with in situ reaction technique in molten aluminum. It was determined that the hardness value of the composites increases with increasing AlB2 reinforcement content within matrix. Functionally graded AlB2/Al composite materials can be successfully produced with centrifugal casting technique. It is also determined that AlB2 reinforcement ratio of the composite materials ranged from 0 to 7 vol. %. In addition, it was observed that the hardness values of the composites increased with the addition of reinforcement ratio.

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NUMERICAL ANALYSIS OF THE BEHAVIOR OF PRESSURE VESSEL SUBJECT TO VARIABLE REQUESTS USING THE FINITE ELEMENT METHOD

Mihalache Adrian CONSTANTIN; Alin DINITA; Valeriu-Nicolaie PANAITESCU

4/1/2022

DOI: 10.53464/JMTE.

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

The behaviour of a metallic material subjected to the action of a variable stress (which generates mechanical stresses in the material with variable intensities over time) differs significantly from that corresponding to the action of constant or monotonically increasing stresses which do not change in intensity over time or which increase continuously in intensity as time passes), its rupture may occur even if the intensity of the mechanical stresses generated during the stress σ is less than the tensile strength of the material Rm. The article studied the static and dynamic behaviour (fatigue) of an equipment consisting of a jacket and two semi-helical lids.

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ONLINE THERMODYNAMICS EDUCATION UNDER PANDEMIC TIMES, IN CONSTANTA MARITIME UNIVERSITY

Feiza MEMET; Mirela-Iuliana SUNDRI

4/1/2022

DOI: 10.53464/JMTE.

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

As well known, the day of 11 March 2020 will remain in the history as the day in which The World Health Organization (WHO) has declared COVID-19 a pandemic. Under these circumstances, the international higher education was forced to remove the campus activities in online. Constanta Maritime University is one of the universities across the world which moved the educational process from face- to- face to online learning. This was a challenging task for the academic, managing and technical administration and for the students, as well. This paper focuses on the disciplined entitled Thermodynamics 1, encountered in the curricula of the Electromechanics Faculty, Constanta Maritime University. The paper describes the steps done during the online education along the semester, both by students and lecturers. At the end of the semester, students and lecturers had to face another challenge: the online examination. Since in the new conditions, the students had to gain the same knowledge as during the classic educational process, we are providing the results obtained by our students. Their exam was scheduled on June 26, 2020. The number of students attending the online examination was 108. The online report for the examination, available on the online platform of the university, indicates that online 17 students were not able to pass the examination (grade 5). The same chart data shows that 19 students have obtained grades in the range (8,00- 8,50), while 2 students obtained grades in the range (9, 50- 10,00). These results are considered to be encouraging for lecturers and students. This type of examination it is seen as a potential long term examination manner, given its benefits: online generation of the test, online verification and not last, transparency.

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ACOUSTIC SIGNAL ANALYSIS AND CLASSIFICATION BASED ON NEURAL NETWORK ALGORITHMS

Said JAMAL; Yahya BENREMDANE; Yahya BENREMDANE; Jawad LAKZIZ; Said OUASKIT

4/1/2022

DOI: 10.53464/JMTE.

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

This paper presents the results of an innovative approach in the underwater domain of research related to the identification, classification and recognition of maritime targets using acoustic data processed. The “Acoustic Signature” is specific to each target type; it is usually produced by the vibration of the propulsion system of surface vessels caused by their radiation into the water. Therefore, the processing of the frequencies generated by these vibrations is essential for the analysis and the classification of different target type. The purpose of this study is to build an alternative method to identify and classify targets with passive sonars using the TPWS (Two - Pass Split - Windows) filter. In this process, the signal generated by the target is processed in time frequency domain. Then a TPSW algorithm is applied in the frequency domain to reduce the background noise and enhance the frequency lines of the target noise. Finally, an artificial intelligence model is applied to classify targets, taking as inputs the narrowband and the broadband analysis. This classification is based on deep learning process, relied on the training, validation, and test phases in order to enhance the accuracy and reduce the loss. Our results showed that the suggested method is accurate (appx 83.5% SNR = 0db), depending essentially on the signal/noise ratio.

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EFFICIENCY STUDY ON THE AIR CONDITIONING SYSTEM ONBOARD A PASSENGER SHIP

Alexandra-Nicoleta GOARDEȘ; Liviu-Constantin STAN

4/1/2022

DOI: 10.53464/JMTE

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

In the conditions of normal operation of ships, due to the release of heat from various machines and people, the increase in humidity as well as due to various releases of gases from on-board systems or goods being transported, the air in the rooms it degrades, requiring its replacement and processing. In the following we will present the issue associated with ensuring the comfort parameters on board ships, a matter regulated by international provisions on ensuring living conditions for crews - International Code for Safety Management and Pollution Prevention (ISM Code).

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MЕANS OF RЕDUCING THЕ IMPACT ON ARCTIC ЕNVIRONMЕNT OF AN ICЕBRЕAKЕR BALLAST SYSTЕM

Alexandra-Nicoleta GOARDEȘ; Liviu-ConstantinSTAN

4/1/2022

DOI: 10.53464/JMTE.

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

Gеnеrally, icеbrеakеrs havе bееn built as nuclеar-powеrеd Arctic ships, but for rеasons rеlatеd to thе protеction of thе еnvironmеnt, and еspеcially thе Arctic еnvironmеnt, this trеnd has bеgun to changе. A nuclеar icеbrеakеr is a typе of nuclеar-powеrеd motor vеssеl for usе in icе-covеrеd watеrs. In wintеr, thе icе along thе North Sеa routе variеs in thicknеss from 1.2 to 2.0 mеtеrs. Thе icе in thе cеntral parts of thе Arctic Ocеan has an avеragе thicknеss of 2.5 mеtеrs. Nuclеar icеbrеakеrs can pass through this icе at spееds of up to 10 knots (19 km/h). In icе-frее watеrs thе maximum spееd of icеbrеakеrs is up to 21 knots (39 km).

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DEFICIENCY ANALYSIS IDENTIFIED IN PSC INSPECTIONS USING EVENT TREE ANALYSIS

S. M. ESAD Demirci; Kadir CICEK

4/1/2022

DOI: 10.53464/JMTE.

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

In the study, PSC inspections data performed in Paris MoU between the years 2016 and 2020 were analysed with the purpose of providing reasonable decision supports for key stakeholders such as ship operators, national and international authorities, cargo owners and classification societies in terms of enhancing safety on board ship and minimizing sub-standard ships in maritime transport. The probabilistic analysis is conducted with the help of Event Tree Analysis (ETA) method on deficiency risk areas respect to the number of deficiencies in each area. In the analysis, the deficiency risk areas are prioritized respect to the different combination of ship type and ship age. In the analysis made on the inspections data, it was found that the number of deficiencies detected under each relevant main item (deficiency risk areas) show significant variation for type of ship and age of ship. With the conducted analysis, in the study, it is aimed to contribute to the more effective inspection by focusing on certain deficiency risk areas in line with the ship type and ship age in the ship inspections.

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THE PROSPECTIVE POSTURE OF MARITIME EDUCATION IN SUPPORT OF SMART SHIPPING

ERGÜN Demirel

4/1/2022

DOI:10.53464/JMTE.

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

Maritime education covers the main seafarer’s education, but after emerging of a new profession in the maritime sector it has started to cover some other aspects of the industry such as port management, fleet management, shipyard management, etc. Additionally, the exponential development of technology enforced education planners to review and revise their programs frequently to meet the expectation of new technological and management structures. Realizing this situation, academicians in the maritime field should understand the new posture of the maritime industry and define their role and missions in the light of the new requirements of the maritime sector. This research aims to investigate the new role and the missions of maritime education institutes considering developments in science and technology in the next decade. In the first step, it is important to understand technological development affecting the maritime sector and imagine the future structure and requirements of the sector. Based on the results of this study a comprehensive study must be done to define what must be done in the education system to respond to new requirements. This research must be exhaustive and detailed. The problem areas are clearly defined and summarized as findings at the end of this step. These requirements must be adopted with academic programs. Adaptation of these corrective proposals to existing academic programs should be discussed considering how these new proposals are associated with the existing programs and/or matched with other related programs This study will assist the academicians and researchers who work on the development of the maritime education and training system using the results of this study.

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A COMPARATIVE ANALYSIS OF INDOOR POSITIONING TECHNOLOGIES IN SHIPYARD DIGITALIZATION CONTEXT

Ibrahim CIL; Fahri ARISOY; Hilal KILINC; Ahmet Yunus CIL

4/1/2022

DOI:10.53464/JMTE.

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

Purpose: In the last few decades, there has been an increasing growth in research into the use of positioning technologies in open environments. Most of the technologies developed for outdoor environments are used successfully, however, they cannot be considered as fully successful indoors. In this context, various technologies based on Radio Frequency, Infrared, Ultrasound, Magnetic, Optical, and computer vision are proposed to improve positioning indoors. In addition to their individual use, it is also seen in hybrid applications. In particular, Radio Frequency based technologies have potential use in shipyard environments. For this purpose, technologies such as Bluetooth, Ultra broadband, Wireless Sensor Network, Wireless Local Area Network, Radio Frequency Recognition and Near Field Communication are seen as suitable technology options for shipyards. The indoor positioning system is a technology that has the potential to significantly improve work efficiency and safety in the shipyard area. It is difficult to achieve a successful digital transformation of the complex shipyard environment without identifying an Indoor positioning technology for the shipyard. In this study, it is aimed to design a positioning technology that will be most appropriate for the shipyard. Methodology: This paper analyses the challenges for the selection of Indoor positioning system for shipyards in evaluating Indoor-positioning technologies. The methodology followed in this study is a comprehensive comparative analysis of existing IPS technologies on how to digitize shipyards. This article provides an advanced assessment of indoor positioning technologies and their use in the challenging shipyard site. In this context, it provides an evaluation framework for different positioning measures such as accuracy, coverage, scalability, cost, privacy and usability of technologies that can be used within the scope of IPS. Results: The work carried out here on indoor positioning systems and components makes a significant contribution to the shipyard industry. Because it has a great impact on the suitability of technologies, especially in relation to the shipyard environment. Both the evaluation model and solution method, and the Bluetooth-based positioning technology, which stands out at the end of the evaluation, are important contributions of the study. Conclusion: To determine which indoor positioning systems are more suitable for the shipyard environment, both a detailed analysis of the shipyard environment and an evaluation were made to select the most suitable technology. The comparison was made based on observations of the shipyard site and the available literature on the field. This article makes important contributions to future shipyards' application of positioning technologies.

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THE STUDY OF A JIB CRANE FROM A CARGO SHIP

Milis Nilgun CAIBULA

4/1/2022

DOI: 10.53464/JMTE.

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

This paper presents the study of a jib crane from a general cargo ship. There are numerous different types of vessels operating today in the various markets worldwide. Besides, thousands of cargo vessel ply the world’s oceans and seas each year, handling the bulk of international trade. The cranes from cargo ship is required to be adequate stability and strength for each load. All cranes from vessel are mounted on deck of the ship. Having regard in particular to the stress induced at its mounting or fixing points, adequately ballasted, securely anchored and supported by outriggers as necessary to ensure its stability when lifting. A jib from a crane from cargo ship is a type of overhead lifting device that is often used in a smaller work cell area for repetitive and unique lifting tasks. The extreme values of the stresses and reaction forces are determined by the finite element method. In this manuscript, the design of the cargo ship and the study of a jib crane are made using NX software from Siemens.

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STUDY OF CORROSION BEHAVIOR OF 1C45 STEEL COATED WITH ALUMINUM AND COPPER

Mihaela Luminița BĂRHĂLESCU

4/1/2022

DOI: 10.53464/JMTE.01.2022.01

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

In the context of the judicious use of natural resources, the obtaining of the mechanical, electrical or protection or resistance characteristics necessary for their use and the economic optimization, it is necessary to study new methods. The method of deposition of surface layers with the help of pulsed lasers offers new directions of development. The deposition of aluminum or copper on cheap basic materials is economically justified but it is necessary to study their corrosion behavior. The study was performed on a 1C45 base material and on samples of the same material with a surface layer of aluminum and copper. The immersion of the samples for a period of 195 days provided measurable results which led to conclusions on the behavior of these materials in the marine environment. Contrary to expectations, the corrosion was manifested in copper, and aluminum showed a high protection capacity. However, the effects of the environment on the strength of the treated surface must also be taken into account during use.

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A TOOL FOR THE ASSESSMENT OF THERMAL EFFICIENCY OF IDEAL DIESEL CYCLES, PROVIDED TO FUTURE MARINE ENGINEERS

Ionela TICU; Elena GOGU

10/1/2021

10.53464/JMTE.02.2021.11

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

Diesel engines are a type of internal combustion engine widely spread in the maritime sector. In a world depending on fossil fuels, the challenge faced by scientists and professionals consists in the efficient use of this kind of fuels. The future of these engines strongly depends on the efficiency enhancement. Future mechanical engineers have to be trained in order to gain engineering judgement and enterprising attitude. In this respect, this paper deals with a theoretical study focused on the improvement of the efficiency of the ideal Diesel cycle. This type of study was recently introduced in Constanta Maritime University, within Thermodynamics seminar activities, delivered to future marine engineers, enrolled in their third semester. This study will reveal the fact that the efficiency of Diesel cycles is affected by the variation of compression ratio, cut off ratio and specific heats ratio. The results obtained will show that, for the ranges taken into discussion, thermal efficiency might be enhanced by the rise of compression ratio and specific heat ratio values and by lowering cut off ratio values. The study is a predecessor of expensive and time costing experiences and it is also a guidance in the hand of future professionals – able to train them for real solutions.

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THE IMPORTANCE OF ECO-CLUSTERS IN THE CONSTANTA COUNTY

Mirela Iuliana SUNDRI

10/1/2021

10.53464/JMTE.02.2021.10

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

Economic theory and international practice confirm the role of clusters as catalysts for competitiveness based on innovation and internationalization. Europe is facing the challenge of becoming a fair and prosperous society based on a modern, competitive and resource-efficient economy. Mobilizing industrial actors towards a clean and circular economy through in-depth cooperation along value chains as well as the use of new technologies, sustainable solutions and disruptive innovation are critical to achieving this goal. Clusters play an important role in operationalizing smart specialization strategies. Eco-clusters aim to increase the competitiveness of enterprises included in "cluster" structures in sectors of economic relevance, by concentrating resources and developing the production of innovative goods such as technologies, products, services, with the greatest possible reduction of waste. Constanta County, through its strategic positioning, through the concentration of economic activities, education and research is an area of maximum interest for the development of eco-innovation and eco-clusters. This study highlights the premises for the establishment of eco-clusters in the Constanta area, given their role as a driver in greening economic policies in the region and developing partnerships in order to obtain clean products. Through eco-clusters, there are also developments in the process of eco-innovation and implementation of sustainable development strategies in the Constanta area, as a means for a long-term socio-ecological transition.

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ANALYSIS OF THE ENGINE STRUCTURAL AND THERMAL STRESS

Liviu Constantin STAN

10/1/2021

10.53464/JMTE.02.2021.09

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

The paper aims to analyse the demands of four-stroke naval pistons. To begin with, a brief analysis of the evolution of shipbuilding was made. Mechanical requests are produced by the gas pressure force and inertial force of the alternate moving masses. Under its action the piston suffers an axial deformation. The thermal demands appearing in the engine are all the more important as the engine power is higher. The possibility of calculating them is more difficult due to the complexity of the thermogazodynamic phenomena in the engine cylinder. Thus, in the piston head, which comes in contact with both the hot gases and the fresh (much cooler) load, a non-stationary heat flow is installed which leads to a certain thermal regime of the engine. Considering the demands outlined in the last chapter, they lead to the final conclusion that although the most unfavourable loading situation was considered as the maximum pressure during the processes and even exaggerated in establishing the working conditions, the piston is still close to the elastic limit. This demonstrates that the way of calculating the dimensions of the piston is correct and safe, as long as its constructive dimensions are not oversized.

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WASTE MANAGEMENT ON BOARD SEAGOING SHIPS

Liliana Viorica POPA

10/1/2021

10.53464/JMTE.02.2021.08

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

The reality remains uncomfortable, the climate crisis is coming with extreme phenomena more and more devastating around the globe and more and more people and more and more parts of ecosystems are suffering from the greed of large companies and lack of constructive action and coherent decision-makers. There are various types of waste generated during operation, and to be able to implement a waste management system, it is necessary to identify and quantify the different types of waste on board. The purpose of this paper is to examine the responsibilities, management, handling and disposal of ship-generated waste and the requirements for the preparation of an on-board waste management plan.

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THE EIS OPTIONS AT MONITORING THE SPREAD OF POLLUTION IN THE STREAM

Jana PAŘÍLKOVÁ; Zbyněk ZACHOVAL; Jan JANDORA; Šimon POŠPÍŠILÍK; Jan MIKULKA; Jan DUŠEK; David JUŘIČKA; Boriss GJUNSBURGS; Algirdas RADZEVIČIUS; Rytis SKOMINAS

10/1/2021

10.53464/JMTE.02.2021.07

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

Water pollution is one of the most significant problems in the world today and is a global problem. Surface water pollution in streams and reservoirs is reflected in the deterioration of the quality of aquatic ecosystems, including those that occur in their vicinity or follow them. Lack of quality drinking water is one of the main causes of various diseases, which can lead to death, especially in developing countries. Therefore, it is important to detect water pollution in time and anticipate how it could develop and be transported in the stream. Measurements on a physical model are time-consuming and economically demanding, but for a given locality it can provide comprehensive information, including the proposal of possible measures and their verification. It is also a suitable approach for calibration and verification of mathematical models. One of the main tasks in the physical modelling of the spread of pollution in the stream was to find a suitable substance that would simulate the pollution without being aggressive towards the water pumping circuit. The method of electrical impedance spectrometry was chosen for its detection in the stream.

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ENERGY EFFICIENCY IN CONSTANTA HARBOR - A THEORETICAL ASSESSMENT OF THE PERFORMANCE OF A HEAT PUMP FOR HEATING NEEDS, FOR A LESS POLLUTANT ADMINISTRATION OFFICE

Feiza MEMET

10/1/2021

10.53464/JMTE.02.2021.06

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

In accordance with the present energetic exigencies, the energy consumption in port buildings is of a vital importance. From this perspective, heat pumps are less pollutant and more energy efficient options than the traditional heating technologies. This study focuses on an air source heat pump (ASHP), operating in an administration office located in Constanta harbor, Romania, in order to supply heated water during December of 2020. Electrically driven heat pumps are seen as a successful alternative to classical expensive heating means, such as electrical heating or the one based on fossil fuels combustion. Within this research, are investigated influences of the heated water temperatures and exterior air temperatures on the theoretical Coefficient of Performance, the compression ratio and the discharge temperature. The cycle is working with R134a, with 50C superheating and sub cooling. It will be considered that the heated water is supplied in the range (40-50) 0C, while the outdoor air temperature varies in the range (0-10) 0C. Obtained results show that the highest efficiency of the ASHP is obtained for the lowest value of the heated water temperature and for the highest value of the outdoor air temperature. This situation corresponds also to the good working of the compressor of the refrigeration plant, since are seen lowest values of the compression rate and the discharge temperature, as well. This means that the compressor do not consume high amounts of energy and the oil is not damaged because of high temperatures of the refrigerant vapors.

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THE ENERGY POTENTIAL OF BLACK SEA IN ROMANIAN SEASIDE AREA

Valentina JALAN; Dumitru DINU; Raluca RĂDULESCU

10/1/2021

10.53464/JMTE.02.2021.05

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

The Black Sea is considered a relatively calm sea, the optimal choice for the capture process is influenced by the wave regime and its peculiarities. This sea is characterized by winds that blow towards land with greater intensity in January causing the sea to be more agitated and with less power in May, June and July, when the sea was the calmest of the year. It should be noted that the frequency of strong winds is 38%, and of those of low speed of 1m/s of only 1.5%. For the collection of oceanographic and meteorological information, data provided by the Gloria platform located in front of Romania’s coast were is used, as well as records from the three offshore buoys anchored in the Romanian seaside area and which are part of the EMSO EUXINUS research infrastructure managed by National Institute for Research and Development on Marine Geology and Geoecology - GeoEcoMar. In addition, free data such as those provided by the site of the research institute Grigore Antipa were easily accessed. Presently there are three fixed platforms in the Black Sea. Wave energy is underexploited, both worldwide and in the Black Sea. The potential of this type of energy is huge, and the environmental impact is low compared to other renewable energy technologies.

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STABILIZING THE PERIODIC ORBITS IN A CHAOTIC MAPPING DESCRIBING THE DISCRETE HEALTH SYSTEMS VIA PREDICTION-BASED CONTROL

Dumitru DELEANU

10/1/2021

10.53464/JMTE.02.2021.04

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

In the paper the problem of location and stabilization of unstable periodic orbits (UPOs) in discrete systems is investigated via the prediction-based control (PBC). It involves using the state of the free system one period ahead as reference for the control signal. Two types of control gains are tested, the first requiring the knowledge of the UPO to be stabilized and the second depending only on the actual state of the trajectory. The effectiveness of PBC is demonstrated on a chaotic mapping describing the malignant tumor growth. When the results obtained with the two control laws are compared with each other, it is found that the second variant is qualitatively superior, both in terms of convergence and the number of stabilized UPOs, especially for long-period orbits.

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RESEARCH ON OPTIMIZING THE OPERATION OF SHIPS IN CONTAINER TERMINALS

Robert Alexandru DĂINEANU; Dumitru DINU; Mariana PANAITESCU; Fănel-Viorel PANAITESCU

10/1/2021

10.53464/JMTE.02.2021.03

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

The time allotted to a single ship at berth varies greatly depending on the characteristics of the ship, the volume of cargo and its specifications.. Taking into account the service time and the problem of terminals by overcrowding of waiting ships and available berths (which may vary in number, depending on the size of ships already berthed), the average waiting time is calculated and obtained. The operating process is usually sequential, ie each type of cargo is stacked separately from the other types. For this reason, the operating time was considered to consist of four other indicators, which correspond to the main types of cargo of Ro-Ro / Ro-Pax ships: complete trucks, semi-trailers, • passenger cars, vehicles as goods themselves. Also, the time of operation of the goods by the dockers can be formulated by two other different terms: the time related to the ship and the time in the terminal. In this context, we intend to analyze the capacity of the terminal in Constanța Port.. Two different scenarios are considered: a more "common" case for the studied terminal with 40 semi-trailers and 80 trucks to be unloaded and the same amount to be loaded and an "extreme" case in which all goods are composed of semi-trailers ( 160 plus 160 in total). By using simulation models, the values for the optimal quay time were obtained, in relation to the number of units for loading data in the specified scenarios. Using modeling algorithms, we obtain reports of situations that include tables and graphs that allow the optimization of terminal operation.

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ELECTRICAL DRIVE AND CONTROL OF AN ELECTRIC MOTOR STEP BY STEP BY STEP BIPOLAR

Violeta-Vali CIUCUR

10/1/2021

10.53464/JMTE.02.2021.02

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

PWM, (Pulse Width Modulation) is the most effective way to control analog circuits using numerical outputs by changing the duration and frequency of the signal. The duration of each state t1 and t2, so the filling factor, where T = t1 + t2 = constant. If only one of the times (t1 or t2) varies, then the Tt period of a cycle varies, so the f = 1 / T frequency varies. The PWM signal is actually a modulated rectangular signal over the duration by modifying the duration of each period t1, t2 of the cycle as well as the change in frequency. The maximum benefit of a stepper motor can only be obtained if it is ordered correctly, this requiring a direct current source, an electronic switch and a controlled pulse generator (numerical information). The frequency of the CLOCK cycle is measured in Hz and the filling factor is measured in percentage (%). The amplitude of the output signal is constant even if the amplitude of signals producing the fill factor varies.

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Increasing the Efficiency Of Marine Energy Conversion

Violeta-Vali CIUCUR

10/1/2021

10.53464/JMTE.02.2021.01

Marine sciences and engineering; Renewable energies; Marine renewable energies and Sustenability; Advanced technologies for MET; Climate changes

New approaches need to be taken into account in adopting the configuration of residual heat recovery systems, design, operation and control and to consider equipment and the energy conversion process in the perspective of integrated systems in order to increase measurable energy efficiency in existing marine energy systems as well as other new systems.

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