Ice-induced vibration is a significant risk factor for the operational safety and structural stability of offshore oil platforms. If the hazards posed by sea ice, currents, and other environmental loads are not properly assessed, offshore platforms may suffer catastrophic consequences such as collapse, oil spills, and casualties. Due to the uncertainty of ice load and ice-induced vibration, traditional numerical analysis and statistical prediction methods struggle to simultaneously meet the requirements for high-precision early warning and timeliness in ice-induced vibration risk assessment. Therefore, based on the measured winter sea environment data of the JZ20-2MUQ platform in the Bohai Sea, this paper uses the interpretive structural model (ISM) and the expectation maximization (EM) algorithm to construct a Bayesian network model. Quantitative analysis indicates that the main risk factors affecting the vibration of the offshore oil platform in the Bayesian network are ice thickness, ice velocity, ice direction, wind speed, and tidal flow velocity and direction. Furthermore, the accuracy and validity of the model are verified. The average accuracy of the model is over 0.75, and the accuracy of the target node is above 0.9. Verification results confirm that the model has high accuracy and can provide reliable data support for risk prediction.

Ships are prone to icing when navigating in polar low-temperature environments. Excessive ice accumulation can affect ship stability, operational safety, and operability of deck equipment, posing a serious threat to crew safety and hindering the rational development and utilization of polar regions. Ship icing is mainly caused by the splashing of waves, and its physical process can be regarded as the freezing process of a large number of saltwater droplets on a cold surface. Experimental research on the freezing process of a single saltwater droplet is essential for deeper understanding of the mechanism of ship superstructure icing at the mesoscale. For this, experiments are conducted on the freezing and melting of freshwater droplets on cold surfaces, the progress of the phase interface during the freezing process of freshwater droplets, the shape changes of water droplets after freezing, the freezing and melting time are recorded, and the influencing factors of the freezing process of freshwater droplets are analyzed. A saltwater droplet freezing experiment with a 3.5% mass fraction is also conducted, the shape changes, freezing and melting times after freezing are recorded, and the impact of droplet volume and cold surface temperature on the freezing process of the saltwater droplets are analyzed and discussed. The influence of salinity is analyzed and compared by comparing the freezing and melting experimental results of saltwater with those of freshwater droplets. The research outcome can provide data support for the validation of ship icing prediction models and scientific guidance for the development of anti-icing and deicing technologies on structural surfaces.

The structural analysis of the Ro-Ro access demands further investigation due to its complexity and the applicability problems in the requirements of the vehicle deck size of the China Classification Society Rules for Classification of Sea-going Steel Ships. The plate, beam structure and primary supporting members of the Ro-Ro access are studied to establish the descriptive requirements of the vehicle deck plate thickness and the stiffener scantlings by using the theoretical formula derivation and the numerical fitting method. At the same time, the direct calculation requirements for the primary supporting members of the access that meet the unified requirements of the International Association of Classification Societies (IACS) and cover all kinds of loads are formed and then verified through case calculations. The results show that the optimized descriptive requirements and direct calculation requirements have good applicability. This study is of great significance for improving the safety and lightweight level of the Ro-Ro access structure design.

The developing of polar ships is an important support of the polar strategic target in China, while the multi-working conditions of ships sailing in polar ice regions complicate the strength design of the propulsion machinery system - the heart of a vessel. The design principle and the corresponding rules and specifications for the strength of the propulsion shafting of DNV are introduced to ensure the reliability and safety of the ships sailing in polar regions. Regarding the impact of the ice load excitation on the propulsion system and the shafting components, DNV recommends a digital solution considering the excitation of the diesel engine cylinder and the phase angle of the ice load excitation based on its experience. In the current study, the Nauticus Machinery software developed by DNV is used to calculate the torsional vibration of a PC4 polar ship in time and frequency domain. The shafting dimension is then evaluated by using the Palmgren-Miner linear damage rule, and the results of the time-domain analysis are compared with those of the frequency-domain analysis. An iteration procedure has been provided for the design and optimization of the shafting dimension aiming at the strength design of the propulsion shafting for polar ships.

Polar navigation is the guarantee for ships to achieve scientific research and safe navigation in the polar area. At present, there are many studies on the theory of polar navigation in China about the arrangement of Inertial Navigation System (INS), the availability of satellite navigation polar area, multi-sensor integrated navigation, etc. But there are still blanks in the application of polar navigation and ice exploration equipment in the high latitude navigation engineering in the polar area. In order to solve the engineering application problems of the device in the polar region from the system level, the paper combines the theory to analyze the polar environment and ship based in the polar region on the performance of the navigation device, and combines the research status of the ice exploration radar, inertial navigation, satellite navigation, electronic charts, satellite communication and other devices in the polar region, studies the working process of the design of the ice navigation device, and discusses the direction of future research and development of the navigation device in China.

Since 1980s, China has begun to study sea ice in the polar regions, and more accumulation has been made in the natural science of the sea ice than in the relevant engineering application. The engineering properties of the sea ice are of great concern with the increasing value of polar shipping. The physical and mechanical properties are important engineering properties of the sea ice, which determine the rational design and safe operation of the ice engineering. The three-point bending tests under different temperatures are conducted in the low-temperature laboratory to measure the sea ice flexural strength and effective elastic modulus by using the complete ice block that was extracted through the whole ice thickness of the landfast sea ice in the Prydz Bay during the 36th Chinese National Antarctic Research Expedition. The flexural strength and effective elastic modulus are correlated to the sea ice porosity. The lower envelope of the flexural strength and the upper envelope of the effective elastic modulus are used to estimate the bearing capacity of the landfast ice in the Prydz Bay, Antarctica. It can provide a safety guarantee for the unloading on ice in Antarctica. By using the physical properties of the sea ice, the mechanical properties of the sea ice are obtained to design the bearing capacity of the ice layer, which gives a new insight on the ice engineering.

Since the International Convention for the Safety of Life at Sea (SOLAS) came into force in 1974, watertight doors and fireproof doors have become an indispensable and important part of sea-going ships as a means to ensure the safety of crew. The design of the large marine fireproof watertight doors has the higher requirements along with the gradual improvement in the design of cargo ships and large warships. An L-type marine low-threshold A-60 fireproof watertight door with high accessibility is designed for large ships, and the finite element analysis of the door leaf structure is carried out and used as a reference for the design of the large fireproof watertight doors.

The noise of the heating, ventilation and air-conditioning(HVAC) system is the major factor affecting the cabin noise level. The acoustic performance tests have been carried out for the various sizes of the impedance composite muffler and the traditional dissipative muffler, in order to guide the design of the marine HVAC system and to reduce the noise level of the HVAC system. The results show that the basic noise reduction of the dissipative muffler can reach 15dB(A)/m. While for the impedance composite muffler with the twice external size of the dissipative muffler, its noise reduction performance is improved in the low frequency range. However, the A-weighted total noise reduction has not changed significantly for the impedance composite muffler. It can provide reference for the selection of the muffler and the design of the HVAC system.

The quality of ship food storage is directly related to the health of the crew. The preservation of fruit and vegetables, as a difficulty in the food storage, is an important factor affecting the self-sufficiency of the ship food. This paper introduces the principles and characteristics of the popular shipboard technologies for the preservation of fruit and vegetables at present. It also analyzes and discusses the application of the preservation technologies of fruit and vegetables on the different types of the military auxiliary ships from the practicability, economy and feasibility by combining with the characteristics of the food storage requirements for the various types of military auxiliary ships. It can provide reference for the design of the preservation of fruit and vegetables for military ships in the future.