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The advent of deep learning has propelled significant advancements in object detection, thereby enhancing the intelligence of underwater autonomous driving systems. In this paper, we explore the cutting-edge applications of autonomous driving technology in the field of underwater exploration, addressing the pivotal role of target detection in navigating and executing tasks within challenging marine environments. In this study, the object detection capability of such systems is enhanced by integrating deep learning and multisensor fusion technology, especially by combining high-precision sensor data with multitask learning models to achieve efficient and robust detection. Our study has three principal contributions. First, we introduce a novel light perception detection system that combines monocular camera technology with 4D radar. It enriches environmental perception by weaving in radar signals and significantly enhances the accuracy and stability of target detection. Second, we have developed a dual-modal detection framework, named Radar-Picture Detection, which utilizes a parallel sequence prediction method. This approach prioritizes radar signal processing, aiding in the improvement of target detection accuracy in intricate underwater environments. Third, we conducted a comprehensive evaluation of our model's performance using the FloW Dataset, which is specifically curated for identifying floating waste in inland waters through unmanned vessel footage. We not only propel forward the field of target detection for underwater autonomous systems but also establish new avenues and a solid foundation for deploying deep learning and multisensor fusion technology in marine environmental perception. Insights and methodologies from this study are poised to spearhead further developments in autonomous marine exploration, enhancing safety, efficiency, and our understanding of underwater environments. [ABSTRACT FROM AUTHOR]

A hybrid maintenance strategy is proposed, combining reliability-centered and condition-based maintenance strategies to prevent engine failures. A case study on the lubrication deficiency of a ship's main engine bearings was conducted. The reliability-centered maintenance phase is based on reliability-increasing rules, equipment facts, and a knowledge base. Then, a strategy is developed where system parameters are continuously monitored. These parameters are evaluated in the inference engine, and maintenance recommendations are provided to the ship operator. The investment cost of th developed system is discussed using a real engine failure case. The study shows that the strategy can improve maintenance on existing ships and system reliability at low costs. The methodology offers a cost-effective approach for the sustainability of the main engine, as demonstrated by a real crankshaft failure report. Unlike existing practices, it provides influential maintenance decisions based on evaluating system parameters within four operation ranges. Simulations show it detects insufficient lubrication faults at low engine loads, superior to current applications. The proposed approach suits different types of existing and newly built ships, engines like dual-fuel, and technologies such as semi-autonomous ships. [ABSTRACT FROM AUTHOR]

The paper aims to investigate the fuel and system options for a floating power plant (FPP) considering economic performance and the decarbonization goals of the International Maritime Organization. Various case studies have been assessed using a reference FPP, encompassing the instant and future retrofitting scenarios. The ready-to-use scenarios involve alternative fuel and organic Rankine cycle-based waste heat recovery system usage. Nuclear energy systems have been evaluated within the reference FPP since they are suitable candidates for achieving zero-carbon objectives and providing low-cost electricity. A simulation framework created in Python has calculated the fuel consumption regarding the power requirement and organized the approaches used in the study. An environmental model comparing the systems has been built to calculate upstream and operational emissions. The cost projection model for 2030 and 2050 has assessed the economic performance. Technique for Order of Preference by Similarity (TOPSIS) one of the multi-criteria decision-making approaches has ranked the systems considering the outcomes of economic and environmental models over the years. Findings demonstrate that the current fuel usage scenario of the FPP is not suitable both environmentally and economically. The other emissions can be near zero and greenhouse gases can be decreased by up to 15.95% using alternative fuels. Nuclear energy is a strong candidate to meet the 2050 targets, but its viability is largely based on economic performance. [ABSTRACT FROM AUTHOR]

The tempering process can increase the mechanical properties of the material, such as hardness and impact strength, as well as enhance the corrosion resistance. Therefore, the selection of appropriate tempering time and cooling environment is crucial. This study aims to investigate changes in properties such as hardness, tensile strength, corrosion resistance, and microstructure of AA5083‐H111 alloy after a brief tempering process (30 minutes, 45 minutes and 60 minutes) at 320 °C, followed by cooling in air and water environments. The study found that tempering time and cooling environment significantly affect the mechanical properties and corrosion rate. The results show that samples labeled as S30 and S60 have the highest hardness and impact strength, but the best corrosion resistance is achieved in the S60 sample. This study demonstrates that even after a limited‐term tempering process, the mechanical properties and corrosion resistance of AA5083‐H111 alloy can be improved. This information is crucial data for use in the production and application of alloys. The findings of this study could have important implications for the production and application of AA5083‐H111 alloy in industries such as aerospace, automotive, and marine engineering. [ABSTRACT FROM AUTHOR]

Understanding accurately the influence of non-plastic fines on stress-dilatancy of coral sand mixture-packing is crucial for marine engineering in various geotechnical applications. This work experimentally examined the effects of non-plastic fines and initial test conditions on stress-dilatancy behavior of mixture. Based on test results, equivalent void ratio ( e ∗ ) was determined to quantify the global effect of fines on shear behavior across different shear stages. Test results show that e ∗ exhibits a reduction as the mean effective stress ( p ′ ) increases, following a power function relationship. Besides, e ∗ variation under phase transformation, peak state, and critical state can be described by a normalized curve. Reduced fines content and increased relative density can contribute to the enhancement of both peak strength and internal friction angle within the mixture. However, the smooth shape and lubrication function facilitated by fines actively contribute to initiation of shear contraction. Furthermore, the stress paths observed in the CD shear tests manifest as a sequence of parallel straight lines within the q - p ′ plane. The length of these lines progressively extends as the stress level escalates. Moreover, deviator stress in q - p ′ curves under character state presents lower and upper limits which are 0.334 and 0.639 corresponding to tested samples determined by fines content and relative density. Elevated fines content combined with reduced relative density can lead to a reduction in both peak-state friction angle and maximum angle of dilation. [ABSTRACT FROM AUTHOR]

The application of remote sensing technology in the retrieval of marine biophysical and physical parameters is becoming increasingly widespread. Accurate atmospheric correction is an essential prerequisite for subsequent retrieval of biophysical and physical parameters of water bodies. However, different atmospheric correction algorithms exhibit significant regional applicability variations across various water body types, requiring researchers to select suitable atmospheric correction algorithms for their study areas. In this study, utilizing Sentinel-2 and Sentinel-3 satellite data sources, global publicly available datasets, and in-situ synchronous measured reflectance data for Type I and Type II water bodies, we evaluated the accuracy of atmospheric correction using three types of algorithms based on radiative transfer, dark spectrum fitting, and neural networks. We analysed the sources of algorithm errors and their applicability from both algorithm principles and water body properties, providing criteria for selecting suitable atmospheric correction algorithms for different characteristic water bodies and proposing recommendations for improving correction accuracy. [ABSTRACT FROM AUTHOR]

Evaluating the filling soil strain and stress behaviors during offshore reclamation and consolidation processes is crucial in forming a stable marine engineering foundation. While, the one-dimensional stress-strain testing technology cannot reflect the three-dimensional (3D) characteristics of the large site, which poses a potential disaster to the uneven settlement of the site. In this study, we construct a platform for 3D testing of strain and stress state during soil consolidation process on the basis of the novel 3D strain rosette and 3D earth stress sensor. Subsequently, the platform was used in a consolidation model test of the Dalian Offshore Airport filling soil, which consists of red clay and stone powder in a mass ratio of 1:4. The results indicate that self-weight consolidation mainly involves an increase in isotropic spherical strain, while load consolidation results in significant shear strain. During soil consolidation process, stress increases first and then dissipates, while vertical compression occurs due to the self-weight of the soil. The evolution law of the principal strain is direction-independent, whereas that of the principal stress remains comparatively stable when the principal stress increases steadily. This study provides a reference for the consolidation deformation and soil strength evaluation of soil fill. [ABSTRACT FROM AUTHOR]

Nickel-based superalloys have gained widespread use in various industries like aerospace, power generation, chemical processing, and marine engineering due to their exceptional mechanical properties. However, machining these superalloys poses significant challenges due to their hardness. To address these issues and improve machining performance, selecting suitable cutting tool materials and coatings is crucial. This state-of-the-art review aims to provide an in-depth understanding of the latest research on cutting tool materials and coatings in enhancing the tool performance in machining the superior nickel-based superalloys. It begins by examining the applications and current challenges associated with machining these alloys. Different types of cutting tool materials, including cemented carbides, ceramic-based tools, and super-hard materials like polycrystalline cubic boron nitride, are analyzed, with a particular focus on tool geometry and failure. The advantages, limitations, and specific applications of each tool material are highlighted. Additionally, the role of coatings in enhancing cutting tool performance is explored. Various coating types, including titanium nitride (TiN), titanium carbonitride (TiCN), and aluminum oxide (Al2O3), are evaluated based on their effectiveness in machining nickel-based superalloys. The review also covers aspects such as tool wear, cutting forces, the surface roughness of machined parts, heat generation, and temperature measurement techniques employed by researchers to assess cutting tool performance. It underscores the importance of tailoring the selection of cutting tool materials and coatings to specific machining conditions for optimal results. The review concludes by summarizing key findings and suggesting potential areas for future research. [ABSTRACT FROM AUTHOR]

Structured marine clay is commonly encountered in offshore engineering projects and engineers are concerned about its impact on the engineering properties of marine clay as well as its correlation with index properties. Current research has emphasized the role of soil structure in these aspects of marine clay. In this study, we investigated the influence of depositional environment and oxidation-induced evolution of clay microstructure on the formation of clay structure in structured clay from Zhanjiang area, a coastal city located in South China. The distinct soil structure observed in marine-terrigenous clay deposited under different environments exhibited sensitivity ranging from 1.6 to 8.9 at varying moisture content levels. The wide range of sensitivity observed in structured marine-terrigenous clay was attributed to free iron oxide derived from siderite present in an acidic environment. Compared to other regions, Zhanjiang marine clay demonstrated favorable mechanical properties but poor physical properties due to its unique clay structure characteristics. Based on these findings, we proposed a modified approach for correlating index properties with engineering properties that yielded good predictions. [ABSTRACT FROM AUTHOR]

This paper explicates the codes that prescribe and shape the marine engineer student in times of massification and high attrition rates in Danish non-university higher education. In a case study of a Danish school of marine engineering, the Bernsteinian concept of knowledge structures and Legitimation Code Theory support analysing the official curriculum along with teacher and student interviews to determine what is considered knowledge and whose knowledge is deemed important. We find that teachers' pedagogical decisions are embedded in the epistemological and social conventions of their individual educational backgrounds. Their struggles on content and pedagogic approach make it difficult for students to understand what is legitimate knowledge and who can claim to be a legitimate knower. To offer more students epistemic access to non-university academic study and increase student success, the epistemic and evaluative logics of the pedagogic discourses to which students are exposed must be clarified and made explicit. [ABSTRACT FROM AUTHOR]

Designing a ship hull to keep the hydrodynamic performance meet the requirements is an indispensable step in the ship's preliminary design. However, in the traditional design process, the design workload is labor-intensive and time-consuming due to the need to estimate a large number of design schemes. To address this issue, this work developed a Neural Network Proxy Model (NNPM) to assist the hydrodynamic resistance prediction for the ship hull design process. The data used in the NNPM construction was supported by two Computational Fluid Dynamic (CFD) methods with different fidelity where the low-fidelity one for tuning and pre-training, and the high-fidelity one for fine-training. To mitigate the risk of overfitting stemming from disparities in data volumes, the parameter freezing strategy is adopted during the high-fidelity dataset-based fine-training. The results obtained from validation numerical experiments indicated that the NNPM exhibited a forecast error of less than 1% when compared to the high-fidelity CFD method. Importantly, this high accuracy is achieved while maintaining a low construction workload, demonstrating the potential of Artificial Intelligence (AI) to predict the hydrodynamic load of hulls in the ship's preliminary design, which can further advance the artificial intelligence-assisted design (AIAD) technology for various marine structures. [ABSTRACT FROM AUTHOR]

This article explores the link between the building of the pioneering motor ship Jutlandia by Barclay Curle & Co. Ltd in 1912 for the East Asiatic Company of Copenhagen and the Burmeister & Wain oil engines which powered it, notably through Scottish shale oil. It traces the difficulties in building and installing machinery that was unfamiliar to Clydeside engineers and the impact that the ultimate success of the vessel had on marine engine building on the Clyde. After the Burmeister & Wain licence was awarded to Harland and Wolff, the North British Diesel Engine Works was created as a joint venture between Barclay Curle and Swan Hunter, brokered by the oil and shipping broker Frederick Lane and financed by oil industry capital. Despite early promise, the First World War and state control of the shale oil industry hampered the wholesale adoption of shale oil fuelled commercial motor shipping. [ABSTRACT FROM AUTHOR]

Turbocharger fouling phenomenon was analyzed from the risk assessment perspective in this study. The research employed exhaust system and turbocharger equipment of commercial ship that equipped with a Doosan-MAN B&W 6S50 MC-C diesel engine was used as the main research materials, and utilized the fuzzy Failure Mode and Effects Analysis (FMEA) based on the expert system as a methodical approach. The experts revealed different types of turbocharger fouling failure modes (FMs), along with their respective causes and subsequent consequences. Following that, the specialists allocated an O, S, and D score to each FM. Within the framework of fuzzy logic, the process entails the establishment of input and output membership functions, as well as the construction of a fuzzy model incorporating an inference mechanism and a rule base. Based on the analysis findings, the three primary factors are as follows: low cylinder compression pressure with a Fuzzy Risk Priority Number (FRPN) score of 6.95, high main engine fuel oil consumption with a score of 6.92, and high CO, CO2, SOx emissions with a 6.45. The phenomenon of turbocharger fouling, being an inherent occurrence, has significant ramifications on the main engine, the vessel as a whole, and the ecological surroundings. The quantitative results presented in this study provide valuable insights into the risks associated with maritime endeavors. The data generated from this research can be used by stakeholders in the maritime industry to better understand this situation and take proactive measures to mitigate potential risks in the future. Furthermore, the findings of the research provide corroboration for the implementation of predictive maintenance procedures. [ABSTRACT FROM AUTHOR]

This study focuses on the successful fabrication of a cost-effective strain sensor using exclusively additive manufacturing Fused Deposition Modeling (FDM) technology, enabling fast on-site production, which is particularly advantageous in maritime settings, reducing downtime, and supporting a circular economy approach by minimizing inventory needs and environmental footprint. The principle of operation of the developed device is based on the piezoresistive characteristics of a carbon nanotube (CNT)-enriched building material, from which the main sensing element consists. The prototype exhibited reliable piezoresistive properties, and a clear correlation was observed between the thermal treatment of the printed piezoresistor and the resulting gauge factor, linearity, and hysteresis. Its robustness, simple design, and single-step manufacturing process, together with its ability to be integrated into the readout circuitry through standard soldering, enhance its reliability and durability. The key advantages of the proposed device include its low cost, simple design, and rapid remote production. [ABSTRACT FROM AUTHOR]

The ocean is the largest carbon reservoir on Earth and serves as a significant sink for atmospheric CO2. Of the known mechanisms for ocean CO2 absorption, the biological pump is considered the most important for carbon sequestration due to its economic and efficient advantages. Using microalgae to capture CO2 has several advantages, including a short cultivation period, high carbon sequestration efficiency, and a low investment cost. This article provides an overview of the methods used to screen algae species in microalgal carbon sequestration technology, as well as the expected effects of carbon sequestration. This article analyzes the appropriate cultivation conditions for algae, including the type of photobioreactor, light intensity, CO2 concentration, and nutritional requirements. The article contends that achieving accurate control of multiple environmental factors during microalgal cultivation and optimizing the internal structure of the cultivation device are key components for improving microalgal biomass production and CO2 fixation ability. The results of life-cycle assessments (LCA) indicate that the production of high-value compounds using microalgae is capable of achieving negative carbon emissions. Finally, this paper evaluates the practicality and economic feasibility of microalgae carbon sequestration and also discusses the future challenges and prospects for the development of this technology. [ABSTRACT FROM AUTHOR]

Research on the marine science and technology innovation efficiency (MSTE) from the perspective of innovation value chain is not only an inevitable requirement for in-depth exploration of Marine science and technology innovation activities, but also an important guidance for the sustainable development and optimization of marine economy. Based on the innovation value chain perspective, the marine science and technology innovation process is divided into three phases: basic innovation, applied research and development, and gainful transformation, and the chain network DEA model is used to measure the MSTE of 11 provinces and municipalities along the coast of China from 2007 to 2021; the modified gravity model and social network analysis are used to examine the spatial correlation network characteristics of the marine MSTE at different phases and their influencing factors. The results show that the spatial correlation of China marine MSTE gradually develops from a sparse and dispersed state to a close trend, and the three phases gradually show a development pattern from unicentre, polycentre and networked. There is no strict hierarchical structure in the spatial correlation network of marine MSTE, the applied research and development and revenue transformation phases are more relevant than the basic innovation phase, and the cross-regional collaborative innovation needs to be improved. The high-efficiency provinces have a strong ability to radiate the MSTE to other provinces, and can absorb a large amount of innovation resources. The spatial correlation network of MSTE development has formed four plates of two-way spillover, broker, net spillover and net benefit in all three phases, and the transmission of kinetic energy of regional MSTE development has obvious gradient characteristics. The strength of government support, marine industry structure, and marine management services are conducive to enhancing the spatial correlation of the three phases of innovation development. Through this study, we can not only grasp the overall pattern and development dynamics of China Marine science and technology innovation, but also deeply analyze the internal logic and formation mechanism of its spatial correlation network structure, so as to provide scientific basis for optimizing resource allocation and improving innovation efficiency. [ABSTRACT FROM AUTHOR]

In the realm of marine environmental engineering, the swift and accurate detection of underwater targets is of considerable significance. Recently, methods based on Convolutional Neural Networks (CNN) have been applied to enhance the detection of such targets. However, deep neural networks usually require a large number of parameters, resulting in slow processing speed. Meanwhile, existing methods present challenges in accurate detection when facing small and densely arranged underwater targets. To address these issues, we propose a new neural network model, YOLOv8-LA, for improving the detection performance of underwater targets. First, we design a Lightweight Efficient Partial Convolution (LEPC) module to optimize spatial feature extraction by selectively processing input channels to improve efficiency and significantly reduce redundant computation and storage requirements. Second, we developed the AP-FasterNet architecture for small targets that are commonly found in underwater datasets. By integrating depth-separable convolutions with different expansion rates into FasterNet, AP-FasterNet enhances the model's ability to capture detailed features of small targets. Finally, we integrate the lightweight and efficient content-aware reorganization (CARAFE) up-sampling operation into YOLOv8 to enhance the model performance by aggregating contextual information over a large perceptual field and mitigating information loss during up-sampling.Evaluation results on the URPC2021 dataset show that the YOLOv8-LA model achieves 84.7% mean accuracy (mAP) on a single Nvidia GeForce RTX 3090 and operates at 189.3 frames per second (FPS), demonstrating that it outperforms existing state-of-the-art methods in terms of performance. This result demonstrates the model's ability to ensure high detection accuracy while maintaining real-time processing capabilities. [ABSTRACT FROM AUTHOR]

Measuring the size of suspended particles in water is crucial in related fields such as environmental engineering, marine engineering, and hydraulic engineering. Considering the size distribution of suspended particles in real rivers, the amplitude (Amp) of the backscattering of particles with sizes ranging from 0.006 mm to 0.030 mm was analysed in this research using a lightweight ultrasonic meter developed by the authors and four probes with bandwidths ranging from 3.0 MHz to 30.0 MHz. In the analysis of Amp measurements for different particle sizes, using 0.008 mm as the reference particle size and converting to the rest of the particle sizes, if the Rayleigh scattering condition is satisfied between the particle sizes and the probe frequency, the conversion error value will be between −10% and 10%. This verifies the correctness of the theoretically derived particle size-Amp theory (the positive power relationship between the particle sizes and the Amp) and reflects the validity constraints of designing this experimental setup. The measurement method based on particle backscattering Amp analysis utilised in this study will help to achieve real-time measurements of suspended particles at river sites. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal "Dalton Transactions: An International Journal of Inorganic Chemistry," published by The Royal Society of Chemistry. It includes various articles covering topics such as synthetic approaches and applications of inorganic compounds, electrode materials, metal-organic frameworks, and catalytic investigations. Additionally, the document includes a correction notice for an article titled "Molybdenum-maltolate as a molybdopterin mimic for bioinspired oxidation reaction." The correction notice provides the correct information for the article, including the names of the authors and the correct page numbers. [Extracted from the article]

Photoelectrochemical (PEC) technology in marine engineering holds significant importance due to its potential to address various challenges in the marine environment. Currently, PEC-type applications in marine engineering offer numerous benefits, including sustainable energy generation, water desalination and treatment, photodetection, and communication. Finding novel efficient photoresponse semiconductors is of great significance for the development of PEC-type techniques in the marine space. Bismuth-based semiconductor materials possess suitable and tunable bandgap structures, high carrier mobility, low toxicity, and strong oxidation capacity, which gives them great potential for PEC-type applications in marine engineering. In this paper, the structure and properties of bismuth binary and mixed-anion semiconductors have been reviewed. Meanwhile, the recent progress and synthetic approaches were discussed from the point of view of the application prospects. Finally, the issues and challenges of bismuth binary and mixed-anion semiconductors in PEC-type photodetection and hydrogen generation are analyzed. Thus, this perspective will not only stimulate the further investigation and application of bismuth binary and mixed-anion semiconductors in marine engineering but also help related practitioners understand the recent progress and potential applications of bismuth binary and mixed-anion compounds. [ABSTRACT FROM AUTHOR]

The digital economy plays an important role in promoting the high quality and sustainable development of the marine fishery economy. Based on the panel data of the digital economy and marine fishery development from 2011 to 2022, we firstly adopted the entropy method to comprehensively evaluate the economy quality level of the digital economy and marine fishing. Secondly, we constructed a two-way fixed effect model to empirically analyze the impact of digital economy development on the marine fishery economy quality and the mediating role of marine green science and technology innovation, and further explored the regional heterogeneity of the digital economy on the marine fishery economy quality. Several findings emerge. The digital economy and the marine fishery economy quality level was relatively low and showed a fluctuating increase. The development of the digital economy can significantly improve the economy quality of marine fishing, and the conclusion was still valid after considering a series of robustness tests. The digital economy can drive the development quality of the marine fishery economy through marine green technology innovation. This paper proposes fostering the advancement of digital technology in the marine fishery sector, to effectively harness the innovation-driven potential of the digital economy, so as to facilitate the harmonious development of both the marine and digital economies. [ABSTRACT FROM AUTHOR]

• Development of novel inverse differential quadrature tool for curved beam analysis. • Three-order improvement in accuracy with iDQM compared to DQM solutions. • 98% computational savings versus DQM-based Strong Unified Formulation. • Greater accuracy of higher-order derivatives than lower order Finite elements required for transverse shear stress recovery. Recent advancements in fibre placement technologies have expanded the potential applications of variable stiffness curved composite beams in industries such as aerospace, automotive, and naval engineering. Accurate solution techniques for examining these beams, especially those composed of advanced composite materials, are indispensable. In view of this demand, this study proposes a new high-order computational tool that combines the higher-order accuracy of the emerging inverse differential quadrature method (iDQM) and the simple kinematics of the Timoshenko beam theory for efficient and accurate prediction of the static behaviour of both constant stiffness and variable stiffness curved beam structures. This novel application of iDQM to curved beam analysis is leveraged upon its excellent potential to mitigate differentiation-induced errors by using the so-called indirect approximation strategy. Simple procedures for implementing different orders of iDQM models are presented to analyse curved beam problems, and are independently benchmarked against closed-form Navier's solutions, as well as numerical solutions obtained through the differential quadrature method (DQM) and finite element method (FEM), demonstrating excellent spectral accuracy. Furthermore, the iDQM scheme offers outstanding potential in recovering transverse shear stress, achieving superior accuracy over lower-order FEM in approximating higher-order derivatives. Remarkably, iDQM predictions for variable stiffness curved beams exhibit satisfactory agreement with the Strong Unified Formulation, achieving over 98% computational efficiency. Finally, convergence analysis of iDQM solutions reveal up to three orders of improved accuracy and faster convergence rates compared to the DQM, constituting a new benchmark for curved beam analysis. [ABSTRACT FROM AUTHOR]

Aluminum plays a crucial role in marine structural engineering. However, the presence of Cl− in the ocean leads to erosion of the alumina film and subsequent destruction of aluminum alloy workpieces. To enhance the corrosion resistance of aluminum and improve the bonding force between the plating layer and the matrix, a Cu/Co-Mo amorphous plating layer was intentionally applied to its surface. By exploring the process parameters during the preparation process and using the polarization curves as a measure of variation, the optimum parameters for the preparation of the plated layers were obtained. The results demonstrated that the optimal process parameters were achieved with a current density of 75 mA cm−2, temperature of 45°C, concentration of Na2MoO4 of 0.04 mol L−1, and time of 45 min. XPS testing revealed that the oxide film formed by the plating played a crucial role in preventing further damage caused by Cl−. In addition, the layers prepared under the optimum process parameters are subjected to a variety of tests, including XRD, SEM, AFM, and EIS. [ABSTRACT FROM AUTHOR]

Corrosion protection of steel bars in alkaline concrete environments poses a common challenge in marine engineering. One approach to mitigate steel bar corrosion is the addition of corrosion inhibitors to the concrete. In alkaline environments, the passivation of rebars occurs through anodic passivation coupled with the cathodic oxygen reduction reaction (ORR). The catalysis of ORR can expedite anode passivation. To investigate the corrosion inhibition of steel bars in alkaline environments, meso‐tetra(4‐carboxyphenyl)porphine (TCPP), known for its ORR catalytic properties, is selected. TCPP forms adsorption films on the surface of steel bars, facilitating the formation of passivation films. TCPP primarily adsorbs onto active sites on the surface of the passivation film, where lattice iron ions have leached. The adsorbed TCPP accelerates the formation of the passivation film through ORR catalysis, inhibiting the development of passivation film defects and enhancing the integrity and protection of the passivation film. The most significant effect is observed when the concentration of TCPP is 0.5 mmol/L. The physical adsorption of TCPP is primarily determined by the negative charge centers, namely the carboxyl group O and the pyrrole N. However, due to steric hindrance caused by the unrestricted rotation of the carboxyl benzene, the pyrrole N does not play a dominant role in chemical adsorption. Instead, the active site for chemical adsorption is the carboxyl group O. The adsorption process significantly reduces the diffusion coefficient of TCPP molecules, providing a robust and stable adsorption binding. Phthalocyanine molecules without carboxyl benzene groups adopt a planar structure, allowing them to form stable adsorption configurations on the iron surface through flat adsorption. This observation provides guidance for the design of novel metal phthalocyanine molecules. Specifically, the development of metal phthalocyanine molecules with modifying groups that are coplanar with the phthalocyanine ring and possess restricted rotation can achieve flat adsorption, improve coverage rate, and enhance adsorption configuration stability. [ABSTRACT FROM AUTHOR]

The application of carbon fiber-reinforced composite materials in marine engineering is growing steadily. The mechanical properties of unbonded flexible risers using composite tensile armor wire are highly valued. However, the curing process generates a certain amount of internal residual stress. We present a detailed analysis of epoxy resin laminates to assess the impact of thermal, chemical, and mechanical effects on the curing stress and strain. An empirical model that correlates temperature and degree of cure was developed to precisely fit the elastic modulus data of the curing resin. The chemical kinetics of the epoxy resin system was characterized using differential scanning calorimetry (DSC), while the tensile relaxation modulus was determined through a dynamic mechanical analysis. The viscoelastic model was calibrated using the elastic modulus data of the cured resin combining temperature and degree of the curing (thermochemical kinetics) responses. Based on the principle of time–temperature superposition, the displacement factor and relaxation behavior of the material were also accurately captured by employing the same principle of time–temperature superposition. Utilizing the empirical model for degree of cure and modulus, we predicted micro-curing-induced strains in cured composite materials, which were then validated with experimental observations. [ABSTRACT FROM AUTHOR]

Bathymetry estimation is essential for various applications in port management, navigation safety, marine engineering, and environmental monitoring. Satellite remote sensing data can rapidly acquire the bathymetry of the target shallow waters, and researchers have developed various models to invert the water depth from the satellite data. Geographically weighted regression (GWR) is a common method for satellite-based bathymetry estimation. However, in sediment-laden water environments, especially ports, the suspended materials significantly affect the performance of GWR for depth inversion. This study proposes a novel approach that integrates GWR with Random Forest (RF) techniques, using longitude, latitude, and multispectral remote sensing reflectance as input variables. This approach effectively addresses the challenge of estimating bathymetry in turbid waters by considering the strong correlation between water depth and geographical location. The proposed method not only overcomes the limitations of turbid waters but also improves the accuracy of depth inversion results in such complex aquatic settings. This breakthrough in modeling has significant implications for turbid waters, enhancing port management, navigational safety, and environmental monitoring in sediment-laden maritime zones. [ABSTRACT FROM AUTHOR]

Rising demand for marine resources has led to a great interest in seabed exploration and mining, while deep-sea environments are faced with cumulative effects of many human activities. Currently, conducting an environmental impact assessment for deep-sea exploration and mining is challenging due to the dynamic nature and a lack of high-quality data. The International Seabed Authority (ISA), which charges with regulating human activities on the seabed beyond the continental shelf, requires contractors to establish both geological and environmental baselines. Also, the ISA provides a general environmental guideline for exploring various seabed resources. However, standardization of its implementation would need to be addressed with specified technical international standards. The marine technology subcommittee of International Standardization Organization (ISO) contributes to the study of standards on deep-sea geological, geophysical and biological surveys, also on marine environmental protection. In this review, we explore two broad aspects of ISO standards: (1) the development of marine geological and geophysical exploration standard, which may help to establish geological map in the seabed area. (2) the current state of development of a series of Marine Environmental Impact Assessment (MEIA) standards, which could standardize the environmental surveys and monitoring activities in the seabed area. We also consider the standardization gap between MEIA and seabed mining, and propose future focus on coordination relationship between marine exploration and environmental protection. [ABSTRACT FROM AUTHOR]

Emergent design failures are ubiquitous in complex systems, and often arise when system elements cluster. Approaches to systematically reduce clustering could improve a design's resilience, but reducing clustering is difficult if it is driven by collective interactions among design elements. Here, we use techniques from statistical physics to identify mechanisms by which spatial clusters of design elements emerge in complex systems modelled by heterogeneous networks. We find that, in addition to naive, attraction-driven clustering, heterogeneous networks can exhibit emergent, repulsion-driven clustering. We draw quantitative connections between our results on a model system in naval engineering to entropy-driven phenomena in nanoscale self-assembly, and give a general argument that the clustering phenomena we observe should arise in many distributed systems. We identify circumstances under which generic design problems will exhibit trade-offs between clustering and uncertainty in design objectives, and we present a framework to identify and quantify trade-offs to manage clustering vulnerabilities. [ABSTRACT FROM AUTHOR]

Large-scale rising bubbles exist in some extreme marine engineering fields, such as the exploitation of combustible ice and submarine volcanism. The violent splitting and coalescence process of large-scale rising bubbles with internal pressure comparable to ambient pressure differs greatly from that of the normal small-scale bubbles and high-pressure bubbles. In this paper, the complex splitting and coalescence characteristics of large-scale rising bubbles are studied with a multi-phase smoothed particle hydrodynamics approach. The effects of the arrangement of bubbles, initial centroid distance, and the ratios of bubble radii on the bubble splitting and coalescence characteristics are investigated. The results show that the arrangement of the bubbles dictates whether or not the two bubbles coalesce and influences the coalescence mode of the bubbles further. When two large-scale bubbles are arranged horizontally, the initial spacing of bubbles has minimal influence on the coalescence features, and they always bounce off each other. When the bubbles are not placed horizontally, the bubbles can coalesce in two modes: direct-absorption coalescence and penetrating reverse-absorption coalescence. When arranged vertically, the initial centroid distance affects the coalescence extent of bubbles, and when the vertical distance exceeds five times the bubble radius, the two bubbles do not interact with each other. When the leading bubble is too large relative to the trailing bubble, the large ratios of bubble radii play negative roles in the coalescence of bubbles. [ABSTRACT FROM AUTHOR]

The extraction of weak acoustic signals under strong background noise is of great significance in the applications of target identification and localization. In this paper, the pulse signal with high randomness is set as the weak signal sound source, random noise and sine sound are used as the background noise. Under the condition of a signal-to-noise ratio of −20 dB, combined with blind source separation and neural network methods, the collected observation signals are subjected to weak sound signal separation and recognition research. The optimization method of centralization and scaling processing is used to eliminate the unfavorable influence of the uncertainty of the separated signal amplitude caused by the blind source separation method on the pattern recognition. The recognition result is verified by the combination of "weak impulse acoustic signal" and "random noise signal," and the output vector (0.99 0.01 0.01) approaches (1 0 0), which is recognized as impulse acoustic signal. By combining blind source separation and neural network methods, the separation and identification of weak pulse signals under the condition of a signal-to-noise ratio of −20 dB can be achieved. [ABSTRACT FROM AUTHOR]

Locating an underwater sensor node over the seabed and acquiring fast, secure data communication between the node and an underwater vehicle could lead to advancements in underwater exploration and marine technology. Currently, the seabed is extensively mapped using multibeam sonar modules, providing detailed information about the bed. Because of its high computational requirements and cost, multibeam sonar is not suitable for this application. The aim of this article is to deploy an experimental setup with a single-beam sonar to localize the node, and then, establish a communication link. The single beam sonar has a 30° beamwidth, which can be improvised to have a full range scan using a custom pan-tilt mechanism setup. To accomplish the full-scale area mapping, underwater servo motors have been used in our customized pan-tilt mechanism. Once the localization is done using a custom pan-tilt mechanism, a line-of-sight optical wireless communication is established with a 200 kbps data rate. The channel is modeled based on the test pool experiments. The channel model is used to simulate underwater optical wireless communication (UOWC) to a longer link length and higher data rate. An underwater link length of 3.13 m was achieved at 1 W and 1 Gbps data rate with a Q factor of 6 and BER of 10−9. For this test setup and simulation parameters, various parameters such as BER and quality factor are examined. [ABSTRACT FROM AUTHOR]

Calcium aluminate cement (CAC) is advantageous in marine engineering, and using materials directly from the sea when mixing CAC can reduce both construction costs and ecological pollution to the sea. However, using seawater as the mixing water in CAC is difficult due to the strength reduction. In this work, CACs were prepared with siliceous minerals (SMs) (diatomite and silica fume (SF)) and sodium chloride solution (SCS) as the mixing water. For comparison, other samples were immersed in SCS rather than mixed with SCS. The strength, mass and length changes of CAC mortars cured at 20°C and 40°C were determined. The phase assemblages and morphology were assessed using X-ray diffraction, thermogravimetric-differential scanning calorimetry and scanning electron microscopy. Using SCS as the mixing water was beneficial to the later strength development of CAC. It promoted the formation of C2ASH8 in CAC pastes and showed no strength loss even when cured at 40°C. The strengths of the SM-modified CAC mortars mixed with SCS were higher than those immersed in SCS. The combination of diatomite and SCS significantly increased the CAC strength, especially at 20°C, while SF contributed to better stability in mass and length. [ABSTRACT FROM AUTHOR]

Marine science technology innovation provides power and guarantees for marine eco-civilization construction, which provides direction and material support for marine science technology innovation. Therefore, the coordinated development of the two is of great significance to the marine economy sustainable development in China's coastal areas. On the basis of clarifying the connotations of marine science technology innovation and marine eco-civilization in China's coastal areas from 2006 to 2019, the mechanism for their coordinated development was analysed. A comprehensive indicator system based on the connotation of the two was constructed, and the coordinated development relationship was empirically tested using the coupled coordination model and the panel vector autoregressive (PVAR) model. The results show that: 1) the level of China's coastal marine science technology innovation continues to improve, gradually forming the core of the development of marine science technology innovation in the north, east and south of Shandong, Shanghai and Guangdong; the level of marine eco-civilization development fluctuating upward trend, showing obvious spatial differentiation characteristics. 2) The degree of coordination of marine science technology innovation and marine eco-civilization is growing over time. There is no causal relationship between marine science technology innovation and marine eco-civilization in the northern marine economic circle, but there is a two-way causal relationship between the two in the eastern and southern marine economic circles. 3) Marine eco-civilization shows a significant positive and continuous impact on marine science technology innovation, and marine science technology innovation shows a long-term, continuous, fluctuating, and lagging impact on marine eco-civilization. The overall role of marine eco-civilization on marine science technology innovation is dominant, and there are significant differences in the impact effects of the two major marine economic circles. [ABSTRACT FROM AUTHOR]

To explore the feasibility of geogrid reinforcement as a promising countermeasure to improve the liquefaction and post-liquefaction resistance of calcareous sand, extensive undrained monotonic and multi-stage triaxial tests were performed on unreinforced and geogrid reinforced calcareous sand with different relative densities. The test results illustrate that pore pressure generation curves of unreinforced and reinforced calcareous sand gradually evolve from S-shaped to hyperbolic-shaped with the increase in relative density, cyclic stress ratio, and effective confining pressure. Following this, a pore pressure model applicable to both unreinforced and reinforced calcareous sand is proposed. The liquefaction resistance of calcareous sand increases with the increase in relative density, whereas an elevated cyclic stress ratio increases its liquefaction susceptibility. A virtually unique relationship can be observed between the liquefaction resistance normalized to the product of phase transformation strength ratio and relative density against the number of cycles for triggering liquefaction, providing an effective means of early assessing sand liquefaction resistance. Moreover, the geogrid exhibits excellent reinforcement efficiency in enhancing the liquefaction resistance of calcareous sand at relative densities of 50% and 70%. During the post-liquefaction stage, increasing relative density and geogrid reinforcement can accelerate the recovery of stiffness and strength for liquefied calcareous sand and improve the post-liquefaction strength. In general, geogrid reinforcement is considered a good alternative to densification for improving the engineering properties of calcareous sand and offers great application prospects in marine engineering construction. • The effects of geogrid reinforcement and relative density on the liquefaction and post-liquefaction behaviors of calcareous sand are investigated. • A pore pressure model applicable to both unreinforced and reinforced calcareous sand is proposed. • The inclusion of geogrid enhances the liquefaction resistance of calcareous sand. • Increasing relative density and geogrid reinforcement accelerate the recovery of stiffness and strength for liquefied calcareous sand and improve the shear strength during the post-liquefaction stage. • Geogrid reinforcement is considered a good alternative to densification for improving the engineering properties of calcareous sand and offers great application prospects in marine engineering construction. [ABSTRACT FROM AUTHOR]

A large number of experiments show that composite materials usually show different modulus properties in tension and compression (bi-modulus). However, for actual composite engineering structures, especially complex models, the numerical simulation calculation is usually based on a single modulus. In order to consider the different modulus characteristics of composite materials in tension and compression, researchers put forward simplified constitutive models of dual-modulus materials. However, these constitutive models have not been verified by a large number of experiments, especially by complex models. In this paper, the GWFMM model is simplified and used to analyze complex structures with different modulus in tension and compression. The experimental results of stiffened plate show that the improved GWFMM model can be used to analyze different modulus of tension and compression of complex stiffened structures. In addition, the influence of elastic modulus ratio in tension and compression under different experimental load conditions is further explored, and the influence law of bending and torsion on structures with bi-modulus is discussed. The relevant conclusions provide reference for the design and optimization of full-scale composite structures in marine engineering. [ABSTRACT FROM AUTHOR]

This article provides an overview of deep ocean expeditions conducted using the MIR-1 and MIR-2 deep manned submersibles. The main objectives of these expeditions were to search for and observe the deepest wooden wreck and the deepest military submarine wreck. The article discusses the techniques and methods employed during these operations. The expeditions were driven by the need to financially sustain the submersibles and the group of professional submariners. Additionally, the article mentions the discovery of a Spanish galleon at a depth of 4,700 meters and the search for a Japanese submarine from World War II. The text also describes two expeditions to locate and explore the wreckage of the I-52 submarine, which sank in 1944. The first expedition in 1995 was unsuccessful due to incorrect coordinates provided by British historians. However, a second expedition in 1998 led by U.S. historian Paul Tidwell successfully located the submarine using archival materials and sonar technology. The exploration of the wreckage revealed significant damage from torpedoes and the absence of gold ingots. Overall, these expeditions were primarily focused on scientific research and the utilization of the MIR submersibles. [Extracted from the article]

Crucial equipment for marine engineering and research, high-power ultra-low frequency sound sources have become necessary with the rapid development of seabed resource exploration, marine environment monitoring, underwater remote target detection, and communication technology. The current ultra-low frequency sound source cannot meet the requirements of practical applications. In this paper, both the finite element method and equivalent circuit method are used to improve the electromagnetic acoustic transducer, focusing on solving the structural design of the functional parts of the transducer, as well as the mechanical, electrical, magnetic parametrization of the transducer and other key technologies. The structural parameters and material parameters in the transducer that affect the final performance response are obtained through the optimization of the genetic algorithm. The results show that the electromagnetic acoustic transducer studied in this paper can emit low-frequency sound waves below 50 Hz, and the maximum sound pressure level reaches 138 dB, which meets the requirements of general low-frequency high-power acoustic wave transducers in practical work. [ABSTRACT FROM AUTHOR]

Remote sensing (RS) technologies are extensively exploited by scientists and a vast audience of local authorities, urban managers, and city planners. Coastal regions, geohazard-prone areas, and highly populated cities represent natural laboratories to apply RS technologies and test new methods. Over the last decades, many efforts have been spent on improving Earth's surface monitoring, including intensifying Earth Observation (EO) operations by the major national space agencies. They oversee to plan and make operational constellations of satellite sensors providing the scientific community with extensive research and development opportunities in the geoscience field. For instance, within this framework, the European Space Agency (ESA) and the Ministry of Science and Technology of China (MOST) have sponsored, since the early 2000s, the DRAGON initiative jointly carried out by the European and Chinese RS scientific communities. This manuscript aims to provide a synthetic overview of some research activities and new methods recently designed and applied and trace the route for further developments. The main findings are related to i) the analysis of flood risk in China, ii) the potential of new methods for the estimation and removal of ground displacement biases in small-baseline oriented interferometric Synthetic Aperture Radar (SAR) methods, iii) the analysis of the inundation risk in low-lying regions using coherent and incoherent SAR methods; and iv) the use of SAR-based technologies for marine applications. [ABSTRACT FROM AUTHOR]

This study investigates the prioritization and resource allocation strategies adopted by the coastal local governments of Qingdao, Dalian, and Xiamen in the context of marine regulatory reform aimed at enhancing regulatory efficiency. Data on relevant opinions, departmental requirements, and existing resource allocations were collected through a questionnaire survey. A backpropagation (BP) neural network was then applied to analyze the survey data, prioritize regulatory tasks, and propose resource allocation schemes. The findings demonstrate that integrating machine learning into marine regulation can significantly improve resource utilization efficiency, optimize task execution sequences, and enhance the scientific and refined nature of regulatory work. The BP neural network model exhibited strong predictive capabilities on the training set and demonstrated good generalization abilities on the test set. The performance of the BP neural network model varied slightly across different management levels. For the management level, the accuracy, precision, and recall rates were 85%, 88%, and 82%, respectively. For the supervisory level, these metrics were 81%, 83%, and 78%, respectively. At the employee level, the accuracy, precision, and recall rates were 79%, 81%, and 76%, respectively. These results indicate that the BP neural network model can provide differentiated resource allocation recommendations based on the needs of different management levels. Additionally, the model's performance was assessed based on the employees' years of experience. For employees with 0–5 years of experience, the accuracy, precision, and recall rates were 82%, 84%, and 79%, respectively. For those with 5–10 years of experience, the metrics were 83%, 86%, and 80%, respectively. For employees with over 10 years of experience, the accuracy, precision, and recall rates were 85%, 88%, and 82%, respectively. These data further confirm the applicability and effectiveness of the BP neural network model across different experience groups. Thus, the adoption of machine learning technologies for optimizing marine regulatory resources holds significant practical value, aiding in the enhancement of regulatory capacity and effectiveness within coastal local governments. [ABSTRACT FROM AUTHOR]

Equipment damage, operational and personnel safety are critical for the sustenance of marine engineering and offshore oil and gas projects. Deepwater installation of heavier equipment are usually faced with harsh environmental conditions which could lead to accidents and assets damage if not carefully handled. In this paper, a floating barge with suspended payload and 3-DOF is modelled to investigate the dynamic response of the floating installation system to oscillating loads, wire-rope tensions, and payload positions. By using Velocity Transformation Technique and Lagrange Energy Method the coupled equations of motion system for a 6-DOF multibody dynamic model are established. The coupled equations of motion systems are numerically solved with Fourth-Order Runge-Kutta Method. The accuracy of the proposed model is validated with the existing floating barge model and it performs better than the OrcaFlex and MOSES models. The proposed model will improve operational design for safe ocean engineering and deepwater equipment installations. [ABSTRACT FROM AUTHOR]

With the increase of Liquefied Natural Gas (LNG) fuel‐powered vessels, LNG bunkering vessels have become an important development direction of LNG bunkering technology for its advantages. However, the LNG bunkering vessel operation risk assessment is relatively few. Formal Safety Assessment (FSA) is a novel structured and systematic risk analysis method for Marine engineering, through the data analysis based on probability theory, people can foresee the risk before the accident and take measures to reduce the risk and avoid heavy loss. In this paper, the LNG bunkering vessel operation process is divided into four subprocesses: the loading process, the navigation process, the bunkering process, and the anchoring process. The FSA method is used to identify and evaluate the risks in each process, judge the negligible risk, reasonable and feasible low risk, unacceptable risk, and put forward corresponding safe measures to provide safety guarantees for the operation of LNG bunkering vessels. Through the standardized assessment steps of FSA, a risk model for the LNG bunkering vessel operation process is established, and reasonable suggestions and measures that can effectively control the risk of the LNG bunkering vessel operation process are proposed, the research results of this paper can provide important technical guidance and reference value for the safe operation of LNG bunkering vessel. [ABSTRACT FROM AUTHOR]

In marine engineering, understanding the compressive behaviour of ice is crucial for accurately modelling ice loads on ships and offshore structures in ice-prone waters. Over the past few decades, numerous studies have focused on numerically simulating the ice-crushing process using various material models. A significant source of contention among these models lies in the representation of ice strength envelopes and their evolution with pressure and strain rate. Moreover, there is ongoing debate regarding whether plasticity or viscoelasticity more effectively captures the rheology of ice. Additionally, various flow rules have been implemented in plasticity models and different damage models have been used in viscoelasticity models, all of which play a critical role in simulating ice loads. This critical review aims to shed light on the reasons behind these disagreements and to evaluate the advantages and limitations of the most commonly used models, based on established theories in ice mechanics and empirical evidence. [ABSTRACT FROM AUTHOR]