Steady State Analysis of Towed Marine Cables

Efficient numerical schemes were presented for the steady state solutions of towed marine cables. For most of towed systems,the steady state problem can be resolved into two-point boundary-value problem,or initial value problem in some special cases where the initial values are available directly.A new technique was proposed and attempted to solve the two-point boundary-value problem rather than the conventional shooting method due to its algorithm complexity and low efficiency.First,the boundary conditions are transformed into a set of nonlinear governing equations about the initial values,then bisection method is employed to solve these nonlinear equations with the aid of 4th order Runge-Kutta method.In common sense,non-uniform (sheared) current is assumed,which varies in magnitude and direction with depth.The schemes are validated through the DE Zoysa's example,then several numerical examples are also presented to illustrate the numerical schemes.

Research Review on Marine Search and Rescue

Locating the marine target in a quick and precise way is the crucial point of implementing SAR （search and rescue） at sea, which involves aspects of developing SAR strategy and detects the marine targets. As the effect of marine target detection restricts the SAR result directly, the study has focused on reviewing the previous research about marine target detection, especially dim marine target detection. What＇s more, small target detection under complex sea status is one of the severe challenges which is research＇s hotspot and needs more endeavor. Current research results and future research directions are discussed in the paper. The findings can provide systematic view of implementing maritime search and rescue for field researchers and governors.

Novel Energy-Efficient Opportunistic Routing Protocol for Marine Wireless Sensor Networks Based on Compressed Sensing and Power Control

In marine wireless sensor networks(MWSNs),an appropriate routing protocol is the key to the collaborative collection and efficient transmission of massive data.However,designing an appropriate routing protocol under the condition of sparse marine node deployment,highly dynamic network topology,and limited node energy is complicated.Moreover,the absence of continuous endto-end connection introduces further difficulties in the design of routing protocols.In this case,we present a novel energy-efficient opportunistic routing(Novel Energy-Efficient Opportunistic Routing,NEOR)protocol for MWSNs that is based on compressed sensing and power control.First,a lightweight time-series prediction method-weighted moving average method is proposed to predict the packet advancement value such that the number of location information that is exchanged among a node and its neighbor nodes can be minimized.Second,an adaptive power control mechanism is presented to determine the optimal transmitting power and candidate nodeset on the basis of node mobility,packet advancement,communication link quality,and remaining node energy.Subsequently,a timer-based scheduling algorithm is utilized to coordinate packet forwarding to avoid packet conflict.Furthermore,we introduce the compressed sensing theory to compress perceptual data at source nodes and reconstruct the original data at sink nodes.Therefore,energy consumption in the MWSNs is greatly reduced due to the decrease in the amount of data perception and transmission.Numerical simulation experiments are carried out in a wide range of marine scenarios to verify the superiority of our approach over selected benchmark algorithms.

Compulsory Liability Insurance for Marine Drilling Platforms Pollution under Chinese Law

Compulsory liability insurance has widely existed in the field of marine insurance. However, marine drilling platforms have always been excluded from this system in China. In view of the special legal nature of oil pollution compulsory liability insurance for marine drilling platforms, this paper analyzes a number of issues related to oil pollution compulsory liability insurance, elaborates on the necessity for China to implement the system and makes some suggestions about the implementation of that.

An Efficient and Lightweight YOLOv8s Strawberry Maturity Detection Model

The manual picking of strawberries is inefficient and costly,limiting scalability and economic benefits.Mechanizing this process reduces labor demands,improves working conditions,and modernizes the strawberry industry.Target detection technology,crucial for mechanized picking,must accurately determine strawberry maturity.This study presents an enhanced YOLOv8s model addressing current machine learning issues like accuracy,parameters,and complexity.The improved model replaces the Bottleneck structure in C2f with the FasterNet network,integrates an efficient multi-scale attention mechanism,and uses the Ghost module in the backbone to reduce computational load while maintaining performance.It also introduces Wise-IoU for bounding box regression loss,improving recognition accuracy.The YOLOv8s-FEGW model achieves a 93.8%mAP in detecting strawberry ripeness,with significant reductions in parameters(36.8%),complexity(34.6%),and model size(37.7%),alongside a 12.7% Frames Per Second(FPS)boost.These enhancements result in excellent detection capabilities,supporting agricultural automation and intelligence.

Furnace Temperature Curve Optimization Model Based on Differential Evolution Algorithm

When soldering electronic components onto circuit boards,the temperature curves of the reflow ovens across different zones and the conveyor belt speed significantly influence the product quality.This study focuses on optimizing the furnace temperature curve under varying settings of reflow oven zone temperatures and conveyor belt speeds.To address this,the research sequentially develops a heat transfer model for reflow soldering,an optimization model for reflow furnace conditions using the differential evolution algorithm,and an evaluation and decision model combining the differential evolution algorithm with the Technique for Order Preference by Similarity to Ideal Solution(TOPSIS)method.This approach aims to determine the optimal furnace temperature curve,zone temperatures of the reflow oven,and the conveyor belt speed.

A Review of Current Research and Advances in Unmanned Surface Vehicles

Following developments in artificial intelligence and big data technology,the level of intelligence in intelligent vessels has been improved.Intelligent vessels are being developed into unmanned surface vehicles(USVs),which have widely interested scholars in the shipping industry due to their safety,high efficiency,and energy-saving qualities.Considering the current development of USVs,the types of USVs and applications domestically and internationally are being investigated.USVs emerged with technological developments and their characteristics show some differences from traditional vessels,which brings some problems and advantages for their application.Certain maritime regulations are not applicable to USVs and must be changed.The key technologies in the current development of USVs are being investigated.While the level of intelligence is improving,the protection of cargo cannot be neglected.An innovative approach to the internal structure of USVs is proposed,where the inner hull can automatically recover its original state in case of outer hull tilting.Finally,we summarize the development status of USVs,which are an inevitable direction of development in the marine field.

Study on application of CeO_2 and CaCO_3 nanoparticles in lubricating oils

The ceria （CeO2） nanoparticles and calcium carbonate （CaCO3） nanoparticles were chosen as additives of anti-wear and extreme pressure for lubricating oils, and the morphology and sizes of nanoparticles were examined using Transmission Electron Microscope （TEM）. The tribological performance of lubricating oils containing combined nanoparticles were determined by four-ball friction and wear tester, and the chemical composition of steel ball with worn surface were analyzed by X-ray Photoelectron Spectrurn（XPS）. The results showed that the lubricating oils containing combined nanoparticles had good anti-wear and friction reducing effects, and the tribological properties were optimal when WCeO2＋CaCO3=0.6%, WCeO2：WCaCO3=1：1. The extreme pressure value increased by 40.25%, the wear spot diameter reduced by 33.5%, and friction coefficient reduced by 32% compared with 40CD oil. The coordinated action of big and small particles made anti-wear and friction reducing effective. Tribological chemical reactions resulting from the friction surface formed metal calcium, metal cerium and oxides film, and they could fill up the concave surface and protect the worn surface.

Reviews on Current Carbon Emission Reduction Technologies and Projects and their Feasibilities on Ships

Concern about global climate change is growing, and many projects and researchers are committed to reducing greenhouse gases from all possible sources. International Maritime Organization (IMO) has set a target of 20% CO2 reduction from shipping by 2020 and also presented a series of carbon emission reduction methods, which are known as Energy Efficiency Design Index (EEDI) and Energy Efficiency Operation Indicator (EEOI). Reviews on carbon emission reduction from all industries indicate that, Carbon Capture and Storage (CCS) is an excellent solution to global warming. In this paper, a comprehensive literature review of EEDI and EEOI and CCS is conducted and involves reviewing current policies, introducing common technologies, and considering their feasibilities for marine activities, mainly shipping. Current projects are also presented in this paper, thereby illustrating that carbon emission reduction has been the subject of attention from all over the world. Two case ship studies indicate the economic feasibility of carbon emission reduction and provide a guide for CCS system application and practical installation on ships.

Optimization Design of Minimum Total Resistance Hull Form Based on CFD Method

In order to reduce the resistance and improve the hydrodynamic performance of a ship, two hull form design methods are proposed based on the potential flow theory and viscous flow theory. The flow fields are meshed using body-fitted mesh and structured grids. The parameters of the hull modification function are the design variables. A three-dimensional modeling method is used to alter the geometry. The Non-Linear Programming(NLP) method is utilized to optimize a David Taylor Model Basin(DTMB) model 5415 ship under the constraints, including the displacement constraint. The optimization results show an effective reduction of the resistance. The two hull form design methods developed in this study can provide technical support and theoretical basis for designing green ships.

Microstructural characterization and oxidation resistance of multicomponent equiatomic CoCrCuFeNi–TiO high-entropy alloy

CoCrCuFeNi–TiO was prepared by arc melting of the pure elements and Ti_2CO powder under an Ar atmosphere. Both CoCrCuFe Ni and CoCrCuFeNi–TiO alloys are composed of a face-centered cubic(fcc) solid solution, whereas the alloys of CoCrCuFeNi–TiO are basically composed of an fcc solid solution and TiO crystals. The microstructures of CoCrCuFeNi–TiO are identified as dendrite and interdendrite structures such as CoCrCuFeNi. The morphology of TiO is identified as an equiaxed crystal with a small amount of added Ti_2CO. By increasing the amount of Ti_2CO added, the TiO content was dramatically increased and part of the equiaxed crystals changed to a dendrite structure. A test of the oxidation resistance demonstrates that the oxidation resistance of CoCrCuFeNi–TiO is better than that of CoCrCu Fe Ni. However, as the TiO content increases further, a corresponding decrease is observed in the oxidation resistance.

Formal safety assessment and application of the navigation simulators for preventing human error in ship operations

The International Maritime Organization (IMO) has encouraged its member countries to introduce Formal Safety Assessment (FSA) for ship operations since the end of the last century. FSA can be used through certain formal assessing steps to generate effective recommendations and cautions to control marine risks and improve the safety of ships. On the basis of the brief introduction of FSA, this paper describes the ideas of applying FSA to the prevention of human error in ship operations. It especially discusses the investigation and analysis of the information and data using navigation simulators and puts forward some suggestions for the introduction and development of the FSA research work for safer ship operations.

Research on Bulbous Bow Optimization Based on the Improved PSO Algorithm

In order to reduce the total resistance of a hull, an optimization framework for the bulbous bow optimization was presented. The total resistance in calm water was selected as the objective function, and the overset mesh technique was used for mesh generation. RANS method was used to calculate the total resistance of the hull. In order to improve the efficiency and smoothness of the geometric reconstruction, the arbitrary shape deformation （ASD） technique was introduced to change the shape of the bulbous bow. To improve the global search ability of the particle swarm optimization （PSO） algorithm, an improved particle swarm optimization （IPSO） algorithm was proposed to set up the optimization model. After a series of optimization analyses, the optimal hull form was found. It can be concluded that the simulation based design framework built in this paper is a promising method for bulbous bow optimization.

Dynamic Response Analysis of Towed Cable During Deployment/Retrieval

A numerical approach was developed to analyze the transient behavior of towed cable during ac- tively controlled deployment/retrieval (DR).The cable motion is described by the lumped parameter method, its corresponding boundary conditions are presented.In view of its varying length during DR,two auxiliary arguments are introduced to describe its continuous varying length and discrete number of nodes(equations), the length is determined by the pay out(or reel-in) rate,which is then used to determine the node number by a logic relation.For the discrete mathematical model of towed cable,an algorithm was developed to deal with the discrete governing equations.The simulation results indicate that the cable experiences more com- plex motions due to its varying length,and tension fluctuates seriously in the startup and ending stage of deployment/retrieval.The effect of towing ship's motion in waves on cable during deployment/retrieval is also considered via numerical simulation.

Particle Swarm-Based Translation Control for Immersed Tunnel Element in the Hong Kong–Zhuhai–Macao Bridge Project

Immersed tunnel is an important part of the Hong Kong–Zhuhai–Macao Bridge(HZMB) project. In immersed tunnel floating, translation which includes straight and transverse movements is the main working mode. To decide the magnitude and direction of the towing force for each tug, a particle swarm-based translation control method is presented for non-power immersed tunnel element. A sort of linear weighted logarithmic function is exploited to avoid weak subgoals. In simulation, the particle swarm-based control method is evaluated and compared with traditional empirical method in the case of the HZMB project. Simulation results show that the presented method delivers performance improvement in terms of the enhanced surplus towing force.

Vibration Response Analysis of a New Scientific Research Ship Based on Finite Element Modeling

To control the vibration level of ships under construction,MSC Software’s Patran&Nastran modeling solutions can be used to establish a detailed finite element model of a new manned submersible support mother ship based on a line drawing,including the deck layout,bulkhead section,and stiffener distribution.After a comprehensive analysis of the ship simulation conditions,boundaries,and excitation forces of the main operating equipment,modal analysis and calculation of the ship vibration can be conducted.In this study,we calculated and analyzed the vibration response of key points in the stern area of the ship’s main deck and the submersible warehouse area under design loading working conditions.We then analyzed the vibration response of typical decks(including the compass deck,steering deck,captain’s deck,forecastle deck,and main deck)under the main excitation forces and moments(such as the full swing pod and generator sets).The analysis results showed that under DESIDEP working conditions,the vibration of each deck and key areas of the support mother ship could meet the vibration code requirements of the ship’s preliminary design(using the pod excitation and generator sets).Similarly,the vibration response of a scientific research ship under other loading conditions also met the requirements of the code and provided data support for a comprehensive understanding of the ship’s vibration and noise levels.Using actual vibration measurements,the accuracy of the vibration level simulations using finite element modeling was verified,the vibration of each area of the ship comfortably meeting the requirements of the China Classification Society.

Research on Application of UAV for Maritime Supervision

Unmanned aerial vehicle has low cost, good flexibility, low risk and high efficiency. When it is applied in maritime supervision, such as maritime patrol, sea cruise, investigation and emergency response, maritime search and rescue, navigation channel measurement, monitoring and inspection of the oil and sewage spills from ships at sea, it can effectively expand the uses of monitoring sea areas, reduce the phenomenon of illegal use of sea, which can improve modernization construction in maritime supervision. According to the UAV （unmanned aerial vehicle） development and application, this paper explores the advantages of the UAV application in maritime adminstration, as well as the characteristics of maritime adminstration, put forward some countermeasures and suggestions of UAV applied in maritime adminstration.

Transfer Learning-Based Image Recognition of Nitrogen and Potassium Nutrient Stress in Rice

Nitrogen(N) and potassium(K) are essential elements for rice growth. When N and K are in deficient rice, specific symptoms appear on the leaves that are similar and difficult to distinguish with the naked eye.

Detection of cylinder pressure in diesel engines using cylinder head vibration and time series methods

This paper investigates the vibration characteristics of diesel engine cylinder heads by means of the time series method. With the concept of "Assumed System",the vibration transfer function of real cylinder head structures is established using the autoregressive-moving average models(ARMA models) of cylinder head surface vibration signals. Then this transfer function is successfully used to reconstruct the gas pressure trace inside the cylinder from measured cylinder head vibration signals. This offers an effective means for diesel engine cylinder pressure detection and condition monitoring.

生物柴油在船用低速机上的燃烧分析研究

To study the applicability of biodiesel in marine engines,this research investigated the performance,combustion characteristics,and emission characteristics of biodiesel(B100),diesel,and a 50%volume blend of the two fuels(B50)in a marine engine.This study was conducted on a 4-cylinder,520 mm-bore,two-stroke,low-speed marine engine with a common rail fuel and exhaust gas charge system.The three fuels were tested at different loads from 25%–100%with a step size of 25%.Results showed that the fuel consumption of pure biodiesel increased by about 13.5%and 3.8%relative to that of diesel at 25%and 100%loads,respectively,and by about 6%at 50%and 75%loads.In-cylinder combustion pressure was slightly reduced when the engine ran on biofuel,and black carbon emissions from biodiesel were reduced by an average of 54.7%.Compared with those from diesel,the carbon CO and total hydrocarbon emissions from B100 were reduced by 11.3%and 39%,respectively.Nitroxide emissions were elevated for B100 and B50 under all loading conditions.The properties of B50 blended diesel lie between those of B100 and diesel.In terms of combustion characteristics and emissions,biodiesel can be used without changing the engine parameters and can effectively reduce pollution,such as black carbon and carbon monoxide.