Predict the evolution of mechanical property of Al-Li alloys in a marine environment

The ocean is one of the essential fields of national defense in the future,and more and more attention is paid to the lightweight research of Marine equipment and materials.This study it is to develop a Machine learning(ML)-based prediction method to study the evolution of the mechanical properties of Al-Li alloys in the marine environment.We obtained the mechanical properties of Al-Li alloy samples under uniaxial tensile deformation at different exposure times through Marine exposure experiments.We obtained the strain evolution by digital image correlation(DIC).The strain field images are voxelized using 2D-Convolutional Neural Networks(CNN)autoencoders as input data for Long Short-Term Memory(LSTM)neural networks.Then,the output data of LSTM neural networks combined with corrosion features were input into the Back Propagation(BP)neural network to predict the mechanical properties of Al-Li alloys.The main conclusions are as follows:1.The variation law of mechanical properties of2297-T8 in the Marine atmosphere is revealed.With the increase in outdoor exposure test time,the tensile elastic model of 2297-T8 changes slowly,within 10%,and the tensile yield stress changes significantly,with a maximum attenuation of 23.6%.2.The prediction model can predict the strain evolution and mechanical response simultaneously with an error of less than 5%.3.This study shows that a CNN/LSTM system based on machine learning can be built to capture the corrosion characteristics of Marine exposure experiments.The results show that the relationship between corrosion characteristics and mechanical response can be predicted without considering the microstructure evolution of metal materials.

Corrosion behavior of HVOF Inconel 625 coating in the simulated marine environment

High velocity oxygen fuel(HVOF)spraying process is commonly used to produce superalloy coatings.Inconel 625 coating was prepared on Q235B low carbon steel by HVOF.A series of experiments were conducted to examine the surface and corrosion resistance properties of Inconel 625 HVOF coating.In this paper,potentiodynamic polarization tests and electrochemical impedance spectroscopy(EIS)tests were carried out to evaluate the corrosion resistance of Inconel 625 coating under simulated marine environment.The experiment-al results showed that Inconel 625 coating revealed low porosity and desired coating thickness.Shift in the corrosion potential(E_(corr))to-wards the noble direction combined with much low corrosion current density(i_(corr))indicating a significant improvement of HVOF Inconel 625 coating compared with the substrate.

Bio-inhibitive effect of an algal symbiotic bacterium on corrosion of magnesium in marine environment

It is a longstanding and challenging task to develop sustainable environment-friendly and cost-effective corrosion-protection technologies for Mg alloys, especially under marine conditions in which corrosion can normally be significantly accelerated by bacterial activity. However,this paper reports on the corrosion of highly active Mg interestingly inhibited by an algal-symbiotic bacterium Bacillus altitudinis. The corrosion of Mg in the presence of the bacterium drastically reduced by one order of magnitude after 14 days of immersion. This means that the algal-symbiotic bacterium widely available in natural ocean environments may be employed as a green and sustainable inhibitor in the marine industry. Based on electrochemical measurements, surface analyses and microbe experiments, a combined inhibition mechanism is proposed in the paper to interpret the interesting corrosion behavior of Mg.

Uncertainty analysis for the calculation of marine environmental design parameters in the South China Sea

The calculation results of marine environmental design parameters obtained from different data sampling methods,model distributions,and parameter estimation methods often vary greatly.To better analyze the uncertainties in the calculation of marine environmental design parameters,a general model uncertainty assessment method is necessary.We proposed a new multivariate model uncertainty assessment method for the calculation of marine environmental design parameters.The method divides the overall model uncertainty into two categories:aleatory uncertainty and epistemic uncertainty.The aleatory uncertainty of the model is obtained by analyzing the influence of the number and the dispersion degree of samples on the information entropy of the model.The epistemic uncertainty of the model is calculated using the information entropy of the model itself and the prediction error.The advantages of this method are that it does not require many-year-observation data for the marine environmental elements,and the method can be used to analyze any specific factors that cause model uncertainty.Results show that by applying the method to the South China Sea,the aleatory uncertainty of the model increases with the number of samples and then stabilizes.A positive correlation was revealed between the dispersion of the samples and the aleatory uncertainty of the model.Both the distribution of the model and the parameter estimation results of the model have significant effects on the epistemic uncertainty of the model.When the goodness-of-fit of the model is relatively close,the best model can be selected according to the criterion of the lowest overall uncertainty of the models,which can both ensure a better model fit and avoid too much uncertainty in the model calculation results.The presented multivariate model uncertainty assessment method provides a criterion to measure the advantages and disadvantages of the marine environmental design parameter calculation model from the aspect of uncertainty,which is of great significance to analyze the uncertainties in the calculation of marine environmental design parameters and improve the accuracy of the calculation results.

Microplastics in Marine Environment: Occurrence, Distribution, and Extraction Methods in Marine Organisms

The pervasive presence of microplastics in marine environments has raised significant concerns. This review addresses the pressing issue of microplastic pollution in marine ecosystems and its potential implications for both the environment and human health. It outlines the current state of microplastic occurrence, distribution, and extraction methods within marine organisms. Microplastics have emerged as a significant environmental concern due to their harmful effects on ecosystems and their potential human health risks. These particles infiltrate marine environments through runoff and atmospheric deposition, ultimately contaminating beaches and posing threats to marine life. Despite the gravity of this issue, there has been limited research on the presence and distribution of microplastics in marine organisms. This review aims to bridge this knowledge gap by comprehensively examining the occurrence, distribution, and various extraction methods used to detect microplastics in marine organisms. It emphasizes the urgent need for targeted measures to manage microplastic pollution, highlights the significant role of human activities in contributing to this problem, and underscores the importance of reducing human-induced pollution to safeguard marine ecosystems. While this paper contributes to the understanding of microplastic pollution in marine environments and underscores the critical importance of taking action to protect marine organisms and preserve our oceans for future generations, it also emphasizes that, in effectively tackling the microplastic problem, a well-coordinated approach is essential, involving research initiatives, policy adjustments, public involvement, and innovative technologies. Crucially, prompt and resolute responses must exist to counteract the escalating peril posed by microplastics to the oceans and the global environment.

Influence of Corrosion on the Reliability of SMA Materials in the Marine Environment

The research of new materials on the basis of memory shape today occupies the special attention of researchers in various industrial fields,such as medicine,traffic,robotics,etc.This paper analyzes the possibility of applying SMAs(shape memory alloys)in the maritime industry in terms of monitoring the behavior of SMAs in different marine environments.The subject of the research is Cu-Al-Ni and Ni-Ti CC alloys processed by CC(continuous casting)in the shape of bars and Ni-Ti as cast processed by casting in the shape of disk.Using the method of EDX(energy dispersion X-ray spectrophotometry),the chemical composition of alloy elements in zones such as in the air,on the surface of the sea and in the sea was determined after six and twelve months of exposure.By applying the theory of reliability,an assessment of the reliability of the alloy elements was obtained.According to the obtained results of the Cu-Al-Ni alloy,nickel is the most reliable in the sea.Aluminum is the least reliable in the sea.The Ni-Ti CC alloy in the marine environment is more reliable than the Ni-Ti as cast alloy.Based on the changes in the chemical composition of alloys in all three considered zones,it is concluded that all three alloys have the lowest reliability in the sea and the highest in the air.

Structural strength deterioration of coastal bridge piers considering non-uniform corrosion in marine environments

In the aggressive marine environment over a long-term service period,coastal bridges inevitably sustain corrosion-induced damage due to high sea salt and humidity.This paper investigates the strength reduction of coastal bridges,especially focusing on the effects of non-uniform corrosion along the height of bridge piers.First,the corrosion initiation time and the degradation of reinforcement and concrete are analyzed for bridge piers in marine environments.To investigate the various damage modes of the concrete cover,a discretization method with fiber cells is used for calculating time-dependent interaction diagrams of cross-sections of the bridge piers at the atmospheric zone and the splash and tidal zone under a combination of axial force and bending moment.Second,the shear strength of these aging structures is analyzed.Numerical simulation indicates that the strength of a concrete pier experiences dramatic reduction from corrosion initiation to the spalling of the concrete cover.Strength loss in the splash and tidal zone is more significant than in the atmospheric zone when structures’service time is assumed to be the same.

Risk Assessment of Marine Environments Along the South China Sea and North Indian Ocean on the Basis of a Weighted Bayesian Network

Marine environments have a considerable influence on the construction of the Chinese 21st Century Maritime Silk Road.Thus,an objective and quantitative risk assessment of marine environments has become a key problem that must be solved urgently.To deal with the uncertainty in marine environmental risks caused by complex factors and fuzzy mechanisms,a new assessment technique based on a weighted Bayesian network(BN)is proposed.Through risk factor analysis,node selection,structure construc-tion,and parameter learning,we apply the proposed weighted BN-based assessment model for the risk assessment and zonation of marine environments along the Maritime Silk Road.Results show that the model effectively fuses multisource and uncertain envi-ronmental information and provides reasonable risk assessment results,thereby offering technical support for risk prevention and disaster mitigation along the Maritime Silk Road.

Degradation and Mechanism of the Mechanics and Durability of Reinforced Concrete Slab in A Marine Environment

An experimental research was conducted to determine the corrosion and bearing capacity of a reinforced concrete（RC） slab at different ages in a marine environment.Results show that the development of corrosion-induced cracks on a slab in a marine environment can be divided into three stages according to crack morphology at the bottom of the slab.In the first stage,cracks appear.In the second stage,cracks develop from the edges to the middle of the slab.In the third stage,longitudinal and transverse corrosion-induced cracks coexist.The corrosion ratio of reinforcements nonlinearly increases with the age,and the relationship between the corrosion ratio of the reinforcements and the corrosion-induced crack width of the concrete is established.The flexural capacity of the corroded RC slab nonlinearly decreases with the age,and the model for the bearing capacity factor of the corroded RC slab is established.The mid-span deflection of the corroded RC slab that corresponds to the yield of the reinforcements linearly increases with the increase in corrosion ratio.Finally,the mechanisms of corrosion morphology and the degradation of the mechanical properties of an RC slab in a marine environment are discussed on the basis of the basic theories of steel corrosion in concrete and concrete structure design.

Modeling Boundary and Edge Effect of Chloride Diffusion for Durability Design of Concrete Structures Exposed in Marine Environment

According to the Fick＇s second law of diffusion, six analytical solutions of chloride profile in concrete were studied and discussed with regard to different boundary and initial conditions. In those analytical solutions, the most prevailing error-function solution which is based on semi-infinite assumption is the simple one, but may under-estimate the chloride content in concrete and over-rate the life time prediction of concrete structures. The experimental results show that compared with other solutions, the chloride content in concrete predicted by error-function model is the minimum, and the calculation difference produced by different analytical models should not be ignored. The influence of models on chloride content prediction is more than other environment and material coefficients in some time. In order to get a more realistic prediction model, modification to error-function model is suggested based on analysis and calculation examples concerning the boundary and edge effect.

Drivers of Change in Estuarine and Coastal Marine Environments: An Overview

Anthropogenic climate and non-climate drivers of change are causing significant impacts on estuarine and coastal marine environments. Climate change poses a particular threat to the structure and function of biotic communities in these environments because it acts on the most extensive temporal and spatial scales relative to other anthropogenic drivers of change. The interaction of multiple environmental drivers exacerbates degradation of ecosystem condition. Estuaries are most susceptible to climate-change mediated biotic shifts and direct anthropogenic impacts due to burgeoning human population growth and development in coastal watersheds. Multiple anthropogenic drivers of change, which often interact synergistically, alter physical, chemical, and biological characteristics. Ecological responses may be increasingly nonlinear, with cumulative effects manifested by marked changes in organism abundance, distribution, diversity, and productivity. Detrimental biotic effects in impacted coastal environments cascade up from individual organisms to population and community levels, culminating in ecosystem-level changes including reduced services. Multiple drivers of change and their impacts are increasing in estuarine and coastal marine environments with greater anthropogenic forcing in the coastal zone and global effects of climate change, creating greater challenges for environmental management and conservation programs.

Spatial Heterogeneity of Marine Environment Changes:A Case Study in Laizhou Bay and Its Adjacent Waters,China

Temporal and spatial heterogeneity identifications of marine environment and its changes have great significances in marine spatial planning and offshore pollution control.In this study,considering the integration of marine ecological environment and sea-land interaction,we built a spatialized evaluation model named Marine Environment Change Spatial Assessment(MECSA)to quantify the marine environment status and changes.In MECSA,we applied the geospatial model and the pressure-state-response(PSR)model for processing and integrating evaluation indicators.A case study in the Laizhou Bay showed that the marine environment quality was generally in a declining state from 2009 to 2015.In 2015,the Marine Environment Index(MEI)had decreased by 0.1 compared with 2009,although the two years all reached a‘Good'level.The spatial MEI layers of the two years showed a same distribution:the southwestern part was in poorer status,with a fan ring shape gradually getting better to the northeast.The Marine Organisms Response Index(MORI)contributed the most to the MEI.Therefore,future marine environmental assessment and spatial planning should focus on the identification the marine environment with its changes from the perspective of spatial heterogeneity and systemicity.Based on single indicators and comprehensive evaluation results,we can propose spatially targeted policies and recommendations scientifically.

The marine environmental evolution in the northern Norwegian Sea revealed by foraminifera during the last 60 ka

Both planktonic and benthic foraminifera were identified in a sediment core collected from the northern Norwegian Sea to reconstruct the paleoceanographic evolution since the last glaciation.The assemblages and distribution patterns of dominant foraminiferal species with special habitat preferences indicated that three marine environments occurred in the northern Norwegian Sea since 62 ka BP:(1)an environment controlled by the circulation of the North Atlantic Current(NAC);(2)by polynya-related sinking of brines and upwelling of intermediate water surrounding the polynya;(3)by melt-water from Barents Sea Ice Sheet(BSIS).At 62-52.5 ka BP,a period with the highest summer insolation during the last glaciatial period,intensification of the NAC led to higher absolute abundances and higher diversity of foraminiferal faunas.The higher abundance of benthic species Cibicidoides wuellerstorfi indicates bottom water conditions that were well-ventilated with an adequate food supply;however,higher abundances of polar planktonic foraminiferal species Neogloboquadrina pachyderma(sin.)indicate that the near-surface temperatures were still low.During mid-late Marine Isotope Stage(MIS)3(52.5-29 ka BP),the marine environment of the northern Norwegian Sea alternately changed among the above mentioned three environments.At 29-17ka BP during the last glacial maximum,the dominant benthic species Bolivina arctica from the Arctic Ocean indicates an extreme cold bottom environment.The BSIS expanded to its maximum extent during this period,and vast polynya formed at the edge of the ice sheet.The sinking of brines from the formation of sea ice in the polynyas caused upwelling,indicated by the upwelling adapted planktonic species Globigerinita glutinata.At 17-10 ka BP,the northern Norwegian Sea was controlled by melt-water.With the ablation of BSIS,massive amounts of melt water discharged into the Norwegian Sea,resulting in strong water column stratification,poor ventilation,and an oligotrophic bottom condition,which ledto a drastic decline in the abundance and diversity of foraminifera.At 10-0 ka BP,the marine environment was transformed again by the control of the NAC,which continues to modern day.The abrupt decrease in relative abundance of Neogloboquadrina pachyderma(sin.)indicates a rise in near-surface temperature with the strengthening of the NAC and without the influence of the BSIS.

The Impact of Shipping Accidents on Marine Environment in Albanian Seas

Shipping accidents are unexpected events that result in financial loss and properties,damages and either loss of people.Several reasons as human errors,technical failures,natural conditions,shipping factors,route conditions and cargo related factors play role in these accidents.Unfortunately,shipping accidents are inevitable cases of maritime field,in contravention of creative and innovative technologies in shipping sector and execution of precautionary safety rules and regulations.Marine accidents adversely affect the human,the marine environment,properties and activities aboard ships and ashore in various forms and degree of extent.The effects of accidents vary from minor injuries to fatalities and from insignificant damage to very severe damage to the environment and property.The cost of accidents,including fatalities and injuries,damage to property and the environment,prevention and mitigating measures,and insurance accounts for a considerable share of transport costs.Main purpose of this paper is to investigate the effects of shipping accidents on marine environment in Albanian Seas.Within this scope firstly,the literature related shipping accidents and marine environment were handled.Then,the statistics of shipping accidents and marine environment in Albanian Seas were analyzed.Finally,future projections were provided in the light of presented matters and current developments.

Management Strategies to Mitigate Anthropogenic Impacts in Estuarine and Coastal Marine Environments: A Review

A wide range of anthropogenic activities impacts estuarine and coastal marine environments including interactive climate and non-climatic drivers of change that can significantly degrade biotic communities and habitats. Many of these environments are in decline due to changes in ecosystem structure and function resulting from multiple stressor effects. In addition, inadequate governance has supported a patchwork of single issues or sectoral approaches rather than integrated management of multiple human uses and activities to maintain healthy, productive, resilient, and sustainable ecosystems and the provision of goods and services. Ecosystem-based marine spatial planning is a viable framework for a more effective governance structure and management of these vital coastal environments. An important component of this approach is a holistic effort to assess the environmental, economic, and societal impacts of anthropogenic activities. Thus, a multidisciplinary integrated approach is preferred that links ecological, physical, and socio-economic systems, increasing the protection of resources and societal benefits. For degraded estuarine and coastal marine ecosystems, restoration and rehabilitation initiatives are important intervention strategies used to reverse the loss of habitats and biotic resources and to support management programs. Marine Protected Areas (MPAs) are an integral element of marine management plans to conserve and sustain estuarine and coastal marine environments by protecting threatened ecosystems and their resources from anthropogenic activities. National and international regulatory frameworks and directives are also in place to protect and conserve these environments.

Effects of Environmental Factors on Corrosion Behavior of E690 Steel in Simulated Marine Environment

The effects of hydrostatic pressure, dissolved oxygen, temperature and flow velocity, and their interaction on the corrosion rates of E690 high-strength steel (HSS) in simulated marine environments were studied using response surface methodology. The results show that the flow velocity exerts the most significant influence on the corrosion rate of E690 HSS. Consequently, the corrosion behavior of E690 HSS under varying flow velocities were analyzed profoundly from initial pitting corrosion to long-term corrosion properties. The results indicate that the flow state facilitates the mass transfer and enhances the adsorption tendency of Cl− by enhancing the electrochemical activity of the steel surface. These factors accelerate the electrochemical reactions, resulting in increased pitting density, depth and the long-term corrosion rates in dynamic seawater environments.

The corrosion characteristic and mechanism of Mg-5Y-1.5Nd-xZn-0.5Zr(x=0,2,4,6 wt.%)alloys in marine atmospheric environment

The microstructure and precipitated phases of as-cast Mg-5Y-1.5Nd-x Zn-0.5Zr(x=0,2,4,6 wt.%)alloys were investigated by optical microscopy,scanning electron microscopy,energy-dispersive spectrometry and X-ray Diffraction.The exposure corrosion experiment of these magnesium alloys was tested in South China Sea and KEXUE vessel atmospheric environment.The corrosion characteristic and mechanism of magnesium alloys of Mg-5Y-1.5Nd-x Zn-0.5Zr(x=0,2,4,6 wt.%)alloys were analyzed by weight loss rate,corrosion depth,corrosion products and corrosion morphologies.The electrochemical corrosion tests were also measured in the natural seawater.The comprehensive results showed that Mg-5Y-1.5Nd-4Zn-0.5Zr magnesium alloy existed the best corrosion resistance whether in the marine atmospheric environment and natural seawater environment.That depended on the microstructure,type and distribution of precipitated phases in Mg-5Y-1.5Nd-4Zn-0.5Zr magnesium alloy.Sufficient quantity anodic precipitated phases in the microstructure of Mg-5Y-1.5Nd-4Zn-0.5Zr alloy played the key role in the corrosion resistance.

Scalable rolling-structured triboelectric nanogenerator with high power density for water wave energy harvesting toward marine environmental monitoring

In the context of advocating a green and low-carbon era,ocean energy,as a renewable strategic resource,is an important part of planning and building a new energy system.Triboelectric nanogenerator(TENG)arrays provide feasible and efficient routes for large-scale harvesting of ocean energy.In previous work,a spherical rolling-structured TENG with three-dimensional(3D)electrodes based on rolling motion of dielectric pellets was designed and fabricated for effectively harvesting low-frequency water wave energy.In this work,the external shape of the scalable rolling-structured TENG(SR-TENG)and internal filling amount of pellets were mainly optimized,achieving an average power density of 10.08 W∙m^(−3)under regular triggering.In actual water waves,the SR-TENG can deliver a maximum peak power density of 80.29 W∙m^(−3)and an average power density of 6.02 W∙m^(−3),which are much greater than those of most water wave-driven TENGs.Finally,through a power management,an SR-TENG array with eight units was demonstrated to successfully power portable electronic devices for monitoring the marine environment.The SR-TENGs could promote the development and utilization of ocean blue energy,providing a new paradigm for realizing the carbon neutrality goal.

Effect of Retained Austenite on Corrosion Behavior of Ultrafine Bainitic Steel in Marine Environment

In this study,the impact of retained austenite on corrosion initiation,propagation,and resistance of ultrafine bainitic steels in marine environments based on the one-step and two-step bainitic isothermal transformation was investigated using a combination of theoretical calculations and experimental methods.According to the results,the microstructure of ultrafine bainitic steels was composed of parallel arranged bainite ferrite(BF)and retained austenite(RA).The fraction of the block RA was significantly reduced,whereas the amount of the film RA increased through the two-step bainitic transformation.In the initial stage of corrosion,micro-galvanic effects occurred between the multiphases due to the difference in nobility,leading to the selective dissolution of BF sheaves,which is adjacent to the block RA in the one-step bainitic steel.However,uniformly distributed film RA in the two-step bainitic steel acted as a barrier against corrosion propagation.The electrochemical measurements and neutral salt spray tests revealed a relatively lower corrosion rate for the two-step bainitic steel,indicating a higher corrosion resistance than the one-step bainitic steel.The corrosion products layer mainly consisted ofα-FeOOH,γ-FeOOH,and Fe_(3)O_(4),which were stable and favorable for the formation of a protective rust layer.

Marine environmental quality, pollution monitoring and environmental management

Chinese government has adopted a series of management measures to prevent and manage marine pollution and to protect ocean bio resources and ecosystem. The key points of Chinese marine environmental quality status, pollution monitoring and environmental management since 1980' were discussed in this paper. Those included the investigations of Chinese coast environmental quality, monitoring techniques and standards, as well as the marine environmental management measures. Recent status of marine environmental pollution and the monitoring network in China were also introduced.