Marine Technology Research Articles

Underwater Wireless Optical Communication System Channel Modelling With Oceanic Bubbles and Water Constituents Under Different Wind Conditions

Optical wireless data transmission from an autonomous underwater vehicle (AUV) to a sea-surface buoy has become a viable solution to support the increasing needs for many applications in the field of marine technology. Despite having unique characteristics and advantages, underwater wireless optical communication remains a challenging field due to the difficulties associated with the harsh marine environments and severe attenuation caused by the bubbles and particulates. This study aims to evaluate the uplink UWOC system in the presence of particles and bubbles under various wind speeds. To calculate the link distances and signal loss between a transmitter and a receiver of the UWOC system, simulations were performed with the inputs of the water optical properties obtained from the Bay of Bengal and Southern Ocean waters and bubble properties derived from the Hall-Novarini (HN) model. Consequently, the normalized received power were calculated for the different receiver configurations and oceanic conditions without and with bubbles. Our results showed that the received power decreased with the increasing wind speeds and smaller bubble populations. The angular and spatial distributions of the received beam increased for smaller bubble populations under high wind speeds. When compared to the clean bubbles, the received power slightly decreased for the non-absorbing coated bubbles with different film thicknesses (0.01 ∼ 1.0 μm) and increased for the absorbing coated bubbles with higher thicknesses (≥1 μm). These results will significantly help the system designer to develop and optimize an UWOC system under different bubble populations and wind speed conditions.

СУЧАСНІ МЕТОДИ МАТЕМАТИЧНОЇ ПІДГОТОВКИ МАЙБУТНІХ СУДНОВОДІЇВ

In recent years, the world fleet has changed significantly: new types of ships have appeared, this requires new constructive solutions, many functions that were performed by humans have been transferred to automation. A significant part of working processes on ships is automated, which led to an increase in shipowners' requirements for the qualification of specialists in maritime specialties. Contemporary heavy cargo sea vessels with high speeds can be operated only by highly educated specialists – professionals who have good shipboard training and own the latest methods and means of navigation. This fact largely determines the nature of the training of a modern navigator. Scientists rightly note that the main task of a higher maritime educational institution in the process of training ship navigators is to train specialists who are able and ready to manage modern technical means and a crew, navigate in various, including extreme, situations, and quickly make the right decisions. One cannot but agree with the opinion that despite the constant rapid development of marine technology, seafaring remains an area of increased danger for humans, and therefore a marine engineer must receive a fundamental education, which puts mathematical training in the first place. When considering the mathematical training of cadets of maritime higher educational institutions, it is necessary to take into account the individual abilities of each cadet. There is a need to correctly choose the way, form and methods of organizing educational activities in the process of forming and developing mathematical competence. Their understanding of the need for mathematical knowledge for successful professional activity. The article deals with the expediency of strengthening the mathematical component in the process of training higher education applicants of maritime institutions and presents innovative elements of teaching mathematical disciplines, the application of which in the educational process will make it possible to improve the quality of knowledge in mathematics, which is necessary in the professional activity of a modern navigator. Therefore, the relevance of the work is determined by the need for constant revision and improvement of the fundamental professional training of a modern navigator, in particular its mathematical component.

The impacts of extreme marine weather and marine scientific and technological innovation on marine economic development: Evidence form China’s coastal regions

The extreme marine weather is a very vital factor and has important implications for of marine economic development. However, there is a lack of systematic and quantitative analyses of its impact on the marine economic development. Here, we study the impacts of extreme marine weather on marine economic development of 11 coastal regions in China, using the dynamic panel model. We found that extreme marine weather exerts a significant negative impact on the marine economic development. The marine scientific and technological innovation promotes marine economic development in a prominent manner. The marine scientific and technological innovation slows down the unfavorable impact of extreme marine weather on the marine economy. After considering different industries for marine economic development and heterogeneity, we found that extreme marine weather and marine scientific and technological innovation have a great impact on marine economic development in the tertiary industry and the areas with high development concerning marine economy level, while deliver a small impact on the marine economic development in the primary industry and the areas low development level. This paper empirically studies the relationship between the two variables of marine extreme weather and marine science and technology innovation and its impact on marine economic development, enriches the research perspective of extreme weather on marine economic development, and provides new method evidence for improving the level of marine scientific and technological innovation and promoting the development of marine economy.

Marine Demonstration of Alternative Fuels on the Basis of Propulsion Load Sharing for Sustainable Ship Design

As the IMO aims to reduce greenhouse gas emissions from ships by more than 50% by 2050 compared to 2008, the paradigm of the shipbuilding and shipping industries is changing. The use of carbon-free fuels, such as hydrogen and ammonia, is progressing, along with the incorporation of batteries and fuel cells in ships. With the introduction of various propulsion power sources, the application of electric propulsion systems to ships is also expected to accelerate. The verification of reliability and safety is of paramount importance in the development of new technologies designed in response to environmental regulations. However, maritime demonstration is time-consuming and expensive. Therefore, an effective means of demonstrating the performance, reliability, and safety of various marine carbon-neutral technologies with a small burden is required. This study introduces a ship design for marine demonstration, integrating eco-friendly alternative fuels and electric propulsion system components. We further demonstrate a preparation process for the realization of marine carbon neutrality and future ship design through international joint research, standardization, and ship development, which can be linked to manpower training.

Profiles of Two JOMAE Associate Editors (The Fifth in a Continuing Series)

Profiles of Two JOMAE Associate Editors (The Fifth in a Continuing Series)

Secure Marine Environment Communication: A Multiobject Authentication Protocol Based on Secret Sharing

In the field of marine communication, with the rapid development of the Internet of Things, big data, blockchain, and other new-generation information technology, marine information security is gradually being attached to more and more coastal countries, and marine information technology has ushered in epoch-making development opportunities. However, marine communication networks are open, and marine equipment is vulnerable to attacks on communication systems. On the one hand, a malicious adversary can intercept and analyze information, obtain relevant data with high probability, and even obtain the identity information of the equipment. On the other hand, attackers can also maliciously inject false information. At the same time, it is difficult for the existing marine information security technology to guarantee the confidentiality and authenticity of information simultaneously, which will bring substantial potential hidden dangers to the development of the ocean. We propose a multitarget authentication and key exchange protocol for secure communication. Our protocol assigns complex cryptographic operations to servers, thus balancing the system’s security and efficiency. The secret is divided into multiple subsecrets using the secret sharing feature, and the subsecret information is used to manage the identity credentials of resource-constrained devices. Then, after successful authentication, the server reassigns the subsecret information of the device to achieve the dynamic generation of identity credentials. Meanwhile, a multitarget authentication scheme is proposed based on recovering secrets. In addition, device extension measures are provided to replace or increase devices. Finally, well-established cryptographic assumptions are used to prove the protocol’s security. Simulation results verify the effectiveness of the protocol in multiobjective authentication.

Unearthing marine ecological efficiency and technology gap of China’s coastal regions: A global meta-frontier super SBM approach

With the promotion of the maritime power strategy and progressively increasing and severe environmental problems, marine ecological efficiency is fast becoming an essential object of research in achieving sustainable development. By applying the meta-frontier super SBM model and the global Malmquist-Luenberger index, this paper aims to explore the marine ecological efficiency of coastal regions in China and the technology gaps between different regions during 2006–2017. On this basis, the changes in marine ecological efficiency were decomposed to investigate the driving factors. The results indicate that the marine ecological efficiency of China’s coastal regions was still ineffective, and there was a significant gap between the group production technology and the potential optimal production technology. Also, there was a significant regional technological heterogeneity. The Yangtze River Delta region had optimal production technology level, while the Beibu Gulf region distinctly had a sizeable technological gap with the other three regions. Besides, the primary factor affecting marine ecological efficiency was technological progress. Finally, the results of this paper passed the robustness check. Based on these conclusions, some specific policy suggestions are provided for China’s coastal regions.

HTDet: A Hybrid Transformer-Based Approach for Underwater Small Object Detection

As marine observation technology develops rapidly, underwater optical image object detection is beginning to occupy an important role in many tasks, such as naval coastal defense tasks, aquaculture, etc. However, in the complex marine environment, the images captured by an optical imaging system are usually severely degraded. Therefore, how to detect objects accurately and quickly under such conditions is a critical problem that needs to be solved. In this manuscript, a novel framework for underwater object detection based on a hybrid transformer network is proposed. First, a lightweight hybrid transformer-based network is presented that can extract global contextual information. Second, a fine-grained feature pyramid network is used to overcome the issues of feeble signal disappearance. Third, the test-time-augmentation method is applied for inference without introducing additional parameters. Extensive experiments have shown that the approach we have proposed is able to detect feeble and small objects in an efficient and effective way. Furthermore, our model significantly outperforms the latest advanced detectors with respect to both the number of parameters and the mAP by a considerable margin. Specifically, our detector outperforms the baseline model by 6.3 points, and the model parameters are reduced by 28.5 M.

Maritime Communications: A Survey on Enabling Technologies, Opportunities, and Challenges

Water covers 71% of the Earth’s surface, where the steady increase in oceanic activities has promoted the need for reliable maritime communication technologies. The existing maritime communication systems involve terrestrial, aerial, and space networks. This article presents a holistic overview of the different forms of maritime communications and provides the latest advances in various marine technologies. This article first introduces the different techniques used for maritime communications over the radio frequency (RF) and optical bands. Then, we present the channel models for RF and optical bands, modulation and coding schemes, coverage and capacity, and radio resource management in maritime communications. After that, this article presents some emerging use cases of maritime networks, such as the Internet of Ships and the ship-to-underwater Internet of Things. Finally, we highlight a few exciting open challenges and identify a set of future research directions for maritime communication, including bringing broadband connectivity to the deep sea, using terahertz and visible light signals for on-board applications, and data-driven modeling for radio and optical marine propagation.

Resource Constraints and Economic Growth: Empirical Analysis Based on Marine Field

To explore the contribution of marine resources to marine economic growth, this study uses panel data from 2006–2019 across 11 coastal provinces and cities in China and establishes threshold regression models using marine capital, labor, and science and technology as threshold variables affecting marine resources and economic growth. The findings reveal that the impact of marine resources on marine economic growth only demonstrates a single threshold effect under the primary industry marine resources; in general, with increased capital investment, the marine economy presents a positive development trend. The impact of primary and secondary marine resources on marine economic growth has a single threshold effect of labor input, while the impact of tertiary marine resources on marine economic growth has a double threshold effect of labor input. With investment in marine science and technology, marine resource development and utilization in the primary industries have played a consistent role in promoting marine economic growth. However, the impact of this role is gradually decreasing; marine resource development and utilization in the secondary and tertiary industries shows a development pattern wherein the driving effect of marine economic growth is first large, then small, and then large again. Based on the above analysis, China should promote the transformation of labor-intensive to capital-intensive industries by increasing investment in marine capital, training marine talent, and developing marine science and technology innovation to increase the development level of China’s marine economy.

Empirical study on green development of marine economy driven by marine scientific and technological innovation and its influencing factors

In this study, the green development of marine economy driven by marine scientific and technological innovation is empirically studied and the influencing factors are analyzed. The results show that the development of marine science and technology is significantly positively correlated with the green development of marine economy as a whole, and each input variable has a promoting effect on economic development, but with varied degree of effect. The analysis on the growth models of “Circum-Bohai Sea Economic Zone,” “Yangtze River Delta Economic Zone” and “Pearl River Delta Economic Zone” shows that at present, science and technology in each marine economic zone play an obvious role in promoting economic development, and each input variable plays a different role in promoting the green development of regional marine economy. With the help of threshold panel model, the influences of five factors, namely opening to the outside world, government investment, financial development, human capital and technology investment, on the green development of marine economy driven by marine scientific and technological innovation are investigated, and it is concluded that all kinds of external influencing factors will interfere with the role of marine scientific and technological innovation and achieve the effect of promoting or restricting it.

Micro-Three-Coil Sensor with Dual Excitation Signals Use Asymmetric Magnetic Fields to Distinguish between Non-Ferrous Metals.

Intelligent operation and maintenance technology for vessels can ensure the safety of the entire system, especially for the development of intelligent and unmanned marine technology. The material properties of metal abrasive particles in oil could demonstrate the wear areas of the marine mechanical system because different components consist of different materials. However, most sensors can only roughly separate metallic contaminants into ferromagnetic and non-ferromagnetic particles but cannot differentiate them in greater detail. A micro-three-coil sensor is designed in this paper; the device applies different excitation signals to two excitation coils to differentiate materials, based on the different effects of different material particles in the asymmetric magnetic field. Therefore, a particle's material can be judged by the shape of the induction electromotive force output signal from the induction coil, while the particle size can be judged by the amplitude of the signal. Experimental results show that the material differentiation of four different types of particles can be achieved, namely, of aluminum, iron, 304 stainless steel, and carbon steel. This newly designed sensor provides a new research prospect for the realization of an inductive detection method to distinguish non-ferrous metals and a reference for the subsequent detection of metal contaminants in oil and other liquids.

A literature review and future research agenda on fault detection and diagnosis studies in marine machinery systems

Fault detection and diagnostics (FDD) have great potential to enable safety, efficiency, and reliability measures of critical machinery systems. However, it is clear that there is a lack of systematic literature review to identify and classify the FDD studies conducted within the scope of marine engineering. This paper offers a systematic review of FDD models particular to marine machinery and systems. The numbers of 72 core articles were highlighted through a comprehensive literature review conducted in the 2002–2022 period. The studies are classified based on the mostly utilized methods such as data-driven, model-based, knowledge-based, and new generation-hybrid. In addition, new generation and hybrid methods are discussed in detail. The experimental environment (i.e. shipboard, labs, simulator) and technical details of the conducted studies are extensively discussed. While 56.94% of the examined studies are related to the main engine, 43.06% of them are related to auxiliary engines. In addition, the main and auxiliary engine studies are also divided into subject headings and examined in detail. Given the recent developments in green and smart maritime concepts, a future research agenda of the FDD studies on marine machinery systems is then pinpointed. Consequently, the study stimulates scholars interested in FDD while it enables innovative ideas for marine engineers, technology providers, ship operators, and maritime entrepreneurs.

Assessing the marine ecological welfare performance of coastal regions in China and analysing its determining factors

This study used three-stage data envelopment analysis (DEA) and Tobit regression models to comprehensively evaluate the performance levels, trends, and differences of marine ecological welfare (MEW) in China, and explore its influencing factors to derive relevant policy suggestions. The evaluation results indicate that the three-stage DEA model performed better on MEW than the traditional DEA model by effectively eliminating the influence of random errors and external environmental factors. However, it underestimated the coastal MEW performance of the country. The southern marine economic circle showed an overall improvement, whereas the overall northern marine economic circle did not improve much; the eastern marine economic circle was stable. Moreover, the external environmental factors significantly impacted the performance of MEW, and the value of average MEW performance of each province changed to some extent under the influence of the slack variables of resource consumption and environmental consumption input. Other factors that significantly influenced China’s coastal MEW performance were the level of economic developments on land and government environmental regulations, which correlated positively. Meanwhile, inadequate development momentum in marine research and technology or poor achievement transformation rate negatively influenced it. Finally, countermeasures and suggestions were proposed based on the results of empirical analysis.

Effectiveness of Self-Evaluation, Peer Evaluation and 2nd-Step Self-Evaluation- Covering Anchoring Training in Maritime Education and Training

Evaluation is an essential part of education and training, and it can be used in maritime education and training to help learners organize their knowledge and improve their skills, as well as to improve education and training methods. In this study, self-evaluation and mutual evaluation were conducted during anchoring training on the training ship Shioji Maru belonging to the Tokyo University of Marine Science and Technology. In a survey of students trained in 2020 and 2021 regarding the acquisition of knowledge and skills, 94.5% of students rated themselves as “very effective” or “effective” in their self-evaluation and 92.0% of students rated themselves as “very effective” or “effective” in their mutual evaluation. Comparing the self-evaluation scores with the mutual evaluation scores, it was found that the mutual evaluation scores tended to rank higher than the self-evaluation scores. This is thought to be due to a lack of confidence in one’s own ship handling skills, which leads to harsh evaluations of oneself and more lenient evaluations of others. It was also found that the higher the instructor’s evaluation score, the smaller the difference between the self-evaluation score and the instructor’s evaluation score. Students with higher scores in the instructor’s evaluation were more confident in their ship handling skills, which is thought to indicate that they can evaluate themselves more accurately. On the other hand, self-evaluation was conducted at an early stage immediately after the training, and the bridge operation team and the entire team also conducted the self-evaluation again after the debriefing. In other words, a 2nd-step self-evaluation was conducted through two evaluations conducted at different times. We show the results of a qualitative analysis of the students’ impressions and opinions of these self-evaluations and peer evaluation using the steps for coding and theorization (SCAT) method.

Conferences on Marine Technology in Croatia

Conferences on Marine Technology in Croatia

Detection and classification of man-made objects for the autonomy of underwater robots

Recent developments in marine technologies allow underwater vehicles to perform survey missions for data collection in an automatic way. The scientific community is now focusing on endowing these vehicles with strong perception capabilities, aiming at full autonomy and decision-making skills. Such abilities would bring benefits to a wide range of field applications, e.g. Inspection and Maintenance (I&M) of man-made structures, port security, and marine rescue. Indeed, most of these tasks are currently carried out employing remotely operated vehicles, making the presence of humans in water necessary. Projects like Metrological Evaluation and Testing of Robots in International CompetitionS (METRICS), funded by the European Commission, are promoting research on this field by organising events such as the Robotics for Asset Maintenance and Inspection (RAMI) competition. In particular, this competition requires participants to develop perception techniques capable of identifying a set of specific targets. Within such context, this paper presents an algorithm able to detect and classify Objects of Potential Interest (OPIs) in underwater camera images. First, the proposed solution compensates for the quality degradation of underwater images by applying color enhancement and restoration procedures. Then, it exploits deep-learning techniques, as well as color and shape based methods, to recognize and correctly label the predefined OPIs. Preliminary results of the implemented neural network using restored images are provided, and a mean Average Precision (mAP) of about 92% was achieved on the dataset provided to the RAMI competition participating teams by the NATO Science and Technology Organization Centre for Maritime Research and Experimentation (STO CMRE).

Development Strategy for Marine Scientific Equipment and Technologies

Development Strategy for Marine Scientific Equipment and Technologies

Canada's marine carbon sink: an early career perspective on the state of research and existing knowledge gaps

Improving our understanding of how the ocean absorbs carbon dioxide is critical to climate change mitigation efforts. We, a group of early career ocean professionals working in Canada, summarize current research and identify steps forward to improve our understanding of the marine carbon sink in Canadian national and offshore waters. We have compiled an extensive collection of reported surface ocean air–sea carbon dioxide exchange values within each of Canada's three adjacent ocean basins. We review the current understanding of air–sea carbon fluxes and identify major challenges limiting our understanding in the Pacific, the Arctic, and the Atlantic Ocean. We focus on ways of reducing uncertainty to inform Canada's carbon stocktake, establish baselines for marine carbon dioxide removal projects, and support efforts to mitigate and adapt to ocean acidification. Future directions recommended by this group include investing in maturing and building capacity in the use of marine carbon sensors, improving ocean biogeochemical models fit-for-purpose in regional and ocean carbon dioxide removal applications, creating transparent and robust monitoring, verification, and reporting protocols for marine carbon dioxide removal, tailoring community-specific approaches to co-generate knowledge with First Nations, and advancing training opportunities for early career ocean professionals in marine carbon science and technology.

Research on the Legislation of the Law of Marine Science and Technology from the Strategic Perspective of China's Maritime Power

Research on the Legislation of the Law of Marine Science and Technology from the Strategic Perspective of China's Maritime Power