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Overview of the Development of Flexible Ocean CTD Sensors LI Jihao1, LIN Guanying2, WANG Nuansheng3, LI Yang3, LI Junyang1 Ocean Engineering Equipment and Technology    2024, 11 (3): 69-77.   DOI: 10.12087/oeet.2095-7297.2024.03.11 Abstract （394）      PDF（pc） （5779KB）（1387）       Knowledge map    Save Marine hydrological information plays a significant role in development and exploration of marine resources. Temperature, salinity and depth are fundamental elements of marine hydrology. Monitoring of marine temperature, salinity and depth data plays an important role in the development and utilization of marine resources. The conductivity temperature depth profiler (CTD) is the main instrument for observing seawater temperature and salinity profiles. By using CTD sensors, parameters such as temperature and conductivity of seawater at different depths can be measured. In recent years, flexible electronic sensors have demonstrated great potential for application due to their excellent stretchability and easy attachment, which not only achieve the sensing performance of traditional rigid sensors to a certain extent, but also compensate for the shortcomings of traditional sensors such as large volume and weight. This review introduces the research progress of flexible ocean CTD sensors in recent years, mainly including the working mechanism and classification, common materials, manufacturing processes of flexible sensors, and analyzes the structure, performance, and application platform of existing flexible ocean CTD sensors. Finally, the development of flexible ocean CTD sensors is prospected. Related Articles | Metrics | Comments（0）

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Analysis of the Characteristics of Offshore Wind Power Operation and Maintenance Technologies and Strategies YU Xichong1, LIU Chao1, LIU Xiaoyan1, LI Zhichuan2, WU Yufei1 LI Ouping1 Ocean Engineering Equipment and Technology    2024, 11 (3): 18-21.   DOI: 10.12087/oeet.2095-7297.2024.03.03 Abstract （344）      PDF（pc） （1382KB）（80）       Knowledge map    Save Based on the characteristics of offshore wind power operation and maintenance in China, this paper analyzes the current situation and development trend of offshore wind power operation and maintenance technology and equipment in China. Taking an offshore wind farm in the South China Sea as a research scenario, this paper proposes a vibration monitoring scheme for offshore wind turbine system, an offshore wind turbine boarding scheme, an offshore wind turbine maintenance and operation and maintenance scheme, and an offshore wind farm inspection scheme, which puts forward guiding significance for the operation and maintenance of offshore wind farms in China. Related Articles | Metrics | Comments（0）

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Design and Optimization of Impeller for Underwater Helico-axial Multiphase Pump LIU Yibo1, BI Yuqin1, MA Qiang2, 3, XIAO Huaping1, LIU Shuhai1 Ocean Engineering Equipment and Technology    2024, 11 (4): 14-20.   DOI: 10.12087/oeet.2095-7297.2024.04.03 Abstract （292）      PDF（pc） （2410KB）（129）       Knowledge map    Save As a key equipment in underwater pressurization technology， the underwater helical axial flow mixing pump is widely used in the development of offshore oil and gas fields. How to further enhance its pressurization performance has attracted the attention of researchers. This study adopts a method combining orthogonal experimental design and numerical simulation to optimize 5 key structural parameters of the helical axial flow pump impeller， aiming to improve the pressurization performance of the mixing pump. Using Fluent software and the standard SST k-ω turbulence model， numerical simulations are conducted on a singlestage compression unit of a helical axial flow pump with an impeller shaft diameter of 350 mm. The influence of five different structural parameters of the impeller on the pressurization performance is studied， and the optimal parameter combination is determined. The results show that under the operating conditions of a flow rate of 500 m3/h and a speed of 4500 r/min， the pressurization performance is optimal for a compression unit with three blades， a blade wrap angle of 130°， a blade thickness of 6 mm， and inlet and outlet angles of 6°， achieving 2.02 MPa， which is a 22% improvement in pressurization compared to the initial structure. Finally， numerical simulations are carried out on the optimized threestage mixing pump impeller under different operating conditions to predict the pressurization effect. The research results provide a theoretical basis for the design and optimization of underwater helical axial flow mixing pumps. Related Articles | Metrics | Comments（0）

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Design and Analysis of Mooring System for Hexagonal Floating Photovoltaic Platform SUN Jiayang, CUI Yutao, REN Tie, WANG Yihou Ocean Engineering Equipment and Technology    2024, 11 (4): 29-35.   DOI: 10.12087/oeet.2095-7297.2024.04.05 Abstract （287）      PDF（pc） （9090KB）（333）       Knowledge map    Save Floating photovoltaic platforms， recognized as the most promising technological development direction in the industry， have advantages such as wide application scenarios and low environmental pollution. Their development is of great significance for the development and utilization of offshore solar energy. However， the research on floating photovoltaic platforms in China started relatively late and is still in the empirical stage. As a positioning system for floating photovoltaic platforms， mooring systems can ensure stable operation under extreme sea conditions. Therefore， the design and selection analysis of mooring systems have important research value. This article compares the scattering mooring and group mooring forms of a floating photovoltaic platform in the waters of China， and explores the motion response characteristics and mooring line tension characteristics of different mooring forms of photovoltaic platforms under extreme sea conditions. The research results can provide reference for the reasonable selection and design of photovoltaic platform mooring systems. Related Articles | Metrics | Comments（0）

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Rheological Properties of Epoxy Resin Sealant and Experimental Study of Underwater Sealing LIU Yang, SUN Shiyu, HE Zhenlin, MA Rongtai Ocean Engineering Equipment and Technology    2024, 11 (3): 78-83.   DOI: 10.12087/oeet.2095-7297.2024.03.12 Abstract （233）      PDF（pc） （5087KB）（31）       Knowledge map    Save In this work, the properties and sealing properties of epoxy resin sealants are studied by means of rheology and laboratory simulation experiments. The result shows that the epoxy resin sealant and its components are pseudoplastic fluids with obvious shear thinning properties. The temperature has a significant effect on its properties. The sealant formed by the ratio of material components in 3∶1 presents a high viscosity at 4℃. In addition, Exponential relationship model between viscosity and temperature is proposed by using Arrhenius relationship and experimental data. The result of underwater simulation experiments confirmed that the sealant has good bonding performance and compressive strength, and can be used as a raw material for injection of shallow water sealing structures. Related Articles | Metrics | Comments（0）

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Overview of the Development and Design of Dynamic Cable for Floating Offshore Wind Power in China LIN Zeyin, WANG Yibing, LI Dongsheng Ocean Engineering Equipment and Technology    2024, 11 (4): 41-46.   DOI: 10.12087/oeet.2095-7297.2024.04.07 Abstract （220）      PDF（pc） （2023KB）（673）       Knowledge map    Save In recent years, the global offshore wind power has developed rapidly. As nearshore resources become increasingly scarce, offshore wind power has gradually moved to the deeper sea. To accommodate the dynamic characteristics of floating wind turbines, floating platforms must be supported by dynamic cables. This is a comprehensive cable of transmitting electricity and control signals, with constantly changing position and force status, which can withstand the combined effect of wind, wave, current and other natural environment, to ensure the effective transmission of power and monitoring signals. Compared with foreign industries, Chinas dynamic cable industry started later, with the harsh working conditions and the lack of relevant technology. All these factors restrict the progress of the dynamic cable industry. This paper will provide a detailed introduction to the basic principles, current development status, key technologies, and challenges faced by floating wind turbine dynamic cables, summarizing the latest industry information and technology to support the development of Chinas dynamic cable industry. Related Articles | Metrics | Comments（0）

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Influence of Sea Condition on Tracking Accuracy and Control Energy Consumption of Unmanned Surface Vessels under Straight Line Navigation YONG Jiuqin1, 2, XUE Zhentao1, 2, CHEN Li1, 2 Ocean Engineering Equipment and Technology    2024, 11 (4): 103-109.   DOI: 10.12087/oeet.2095-7297.2024.04.16 Abstract （214）      PDF（pc） （2226KB）（572）       Knowledge map    Save Adaptability to various sea conditions is vital to unmanned surface vessels (USVs). This paper aims to reveal influence of sea conditions on tracking performance. The USV controlled by PID tuned for the baseline sea condition is studied. A three degree of freedom dynamic model is built， and a new evaluation index of control energy consumption accounting for propeller propulsion and steering mechanism operation is designed other than the conventional tracking accuracy. Simulation results demonstrate the variation trend of the tracking accuracy and control energy consumption with sea conditions under the typical straight line navigation case. The performance is significantly affected under high sea conditions， with root mean square error increasing 188 times up to 158.207m and control energy consumption increasing 3 times up to 46.916 kWh. The quantification of the tracking accuracy and control energy consumption with sea conditions provides reference for the design and control of USVs. Related Articles | Metrics | Comments（0）

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The Research on the Selection of Anchor Cable Layout for Submerged Floating Tunnels WANG Jinduo, JI Chong, LI Xin, ZHANG Xiantao Ocean Engineering Equipment and Technology    2024, 11 (3): 10-17.   DOI: 10.12087/oeet.2095-7297.2024.03.02 Abstract （207）      PDF（pc） （1894KB）（282）       Knowledge map    Save Submerged floating tunnels(SFTs) are a new type of transportation structure used to cross deep water. To ensure the dynamic stability of SFTs under wave and current loading, an appropriate mooring system is required. This research focuses on submerged floating tunnels with anchor cables and investigates the impact of different anchor cable layouts on the dynamic response of SFTs. Utilizing OrcaFlex software, finite element models are established to analyze the stiffness of mooring systems under both vertical and inclined layouts. The variations in tunnel displacement, acceleration, and anchor cable tension under regular waves and uniform currents are examined. The results show that the inclined anchor cable layout with an inclination angle of 45° and an installation angle of 45° can effectively suppress the vertical and lateral motion response of the tunnel, ensuring structural stability and preventing anchor cable fatigue damage. Furthermore, this layout is applicable to SFTs of different lengths. Related Articles | Metrics | Comments（0）

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Research on Key Technology of Monpile Foundation Installation in Offshore Wind Farms ZHANG Jianxiang, SONG Yunfeng, LU peng Ocean Engineering Equipment and Technology    2024, 11 (4): 117-124.   DOI: 10.12087/oeet.2095-7297.2024.04.18 Abstract （204）      PDF（pc） （9251KB）（27）       Knowledge map    Save In light of the rapid development of offshore wind power， more economically efficient construction techniques are required. Traditional heavy-duty maritime cranes in construction face high costs and significant risks. On the other hand， the balloon-assisted floatation technology， with its low cost， ease of operation， and ability to reduce crane loads， presents itself as a potential alternative. This article provides an in-depth exploration of the theoretical foundation， technological design， and advantages of balloon-assisted floatation technology， elucidating its potential application prospects in offshore wind turbine single pile foundation construction. Research has shown that the balloon-assisted buoyancy technology offers significant advantages in terms of enhancing construction efficiency， reducing costs， and minimizing environmental impact. It is poised for broad applications in the offshore wind sector in the future. Related Articles | Metrics | Comments（0）

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The Application Risk and Control Measures of S420 Ultra High Strength Steel in Deep Water Jacket WANG Huoping, LUN Yuguo, WANG Deyang, XIAO Wangsui, PENG Yijin Ocean Engineering Equipment and Technology    2024, 11 (4): 47-52.   DOI: 10.12087/oeet.2095-7297.2024.04.08 Abstract （202）      PDF（pc） （2510KB）（21）       Knowledge map    Save n Branch, CNOOC， Shenzhen 257237， Guangzhou China) Abstract Liuhua 11-1 jacket is the deepest deepwater jacket in Asia at present. Compared with shallow water jacket， Liuhua 11-1 jacket has the characteristics of high design risk， long construction cycle， high steel production technology and difficulty in welding. This paper will study the production process of S420 super-strength steel， jacket design risk， construction risk， dynamic performance， welding quality control measures and other aspects， so as to provide reference for similar deepwater jacket project management and control in the future. Related Articles | Metrics | Comments（0）

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Exploration of Underwater Storage Facilities Application Scenarios CAI Wenjuan, CAO Pengwei, ZHAO Ming, ZHOU Qi Ocean Engineering Equipment and Technology    2024, 11 (4): 125-130.   DOI: 10.12087/oeet.2095-7297.2024.04.19 Abstract （199）      PDF（pc） （4331KB）（205）       Knowledge map    Save Underwater storage facilities， leveraging oil-water displacement technology， serve as independent storage units that provide diversified media storage at sea and are essential for the development and utilization of marine energy. This paper analyzes five potential application scenarios for future underwater storage facilities， including the development of marginal oil fields in shallow waters， underwater energy storage technology， underwater methanol and ammonia storage technology， underwater carbon dioxide storage technology， and the storage and injection technology of chemical reagents on the seabed. In marginal oil fields， a combined approach using an integrated processing platform， underwater storage facilities， and shuttle tankers can enhance cost adaptability and the flexibility of storage capacity customization. Underwater energy storage technology (underwater compressed air energy storage and underwater hydrogen storage) is provided for offshore wind platforms to ensure the stability of power transmission and reduce the limitations of storage space on the platform. Offshore wind power can also be converted into methanol and ammonia， by adopting underwater storage solutions. The storage units on the platform can be canceled， thereby reducing overall investment. By installing LCO2 storage facilities underwater instead of storing it on the injection platform， the efficiency of LCO2 storage and its environmental adaptability can be improved. The use of seabed chemical reagent storage and injection technology significantly enhances the safety， cost-effectiveness， and injection accuracy of the chemical reagent system. Related Articles | Metrics | Comments（0）

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Domestically Produced Transformation and Application of Expansion Compressor Rotor Assembly LI Jiucheng Ocean Engineering Equipment and Technology    2024, 11 (4): 36-40.   DOI: 10.12087/oeet.2095-7297.2024.04.06 Abstract （198）      PDF（pc） （5386KB）（9）       Knowledge map    Save Natural gas expansion compressor is the key equipment of natural gas terminal expansion refrigeration process， which plays a vital role in the recovery rate of natural gas byproducts. At present， all natural gas processing terminals use imported expansion compressor sets， but the imported compressor sets have large investment and high maintenance and spare parts costs in the later stage due to technical constraints. Two imported expansion compressors (1.2 million cubic meters/day) that have been used for many years and have frequent failures have been reformed domestically in a onshore terminal of Bohai oil and gas field. The localization transformation of expansion compressor rotor assembly mainly includes expansion end impeller， compression end impeller， main shaft， bearing， diaphragm shaft seal， connecting key and other auxiliary parts. For the first time， the rotor assembly of the imported expansion compressor of natural gas onshore terminal in Bohai area was localized， and the spare parts of the unit did not depend on imports， which was completely independently developed and produced in China. The supply channels were smooth， and the required maintenance spare parts could be purchased in the shortest time， and the technical core parameters were controlled to shorten the maintenance cycle， saving the later maintenance time and cost. The comparison results show that the field application effect of domestic unit parts is good， the unit has been running continuously for 78，840 hours without abnormality， and its performance far exceeds the service life of imported parts， which provides a good reference for similar projects of natural gas expansion refrigeration. Related Articles | Metrics | Comments（0）

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The Development and Performance Test of Chemical Injection Metering Valve Calibration Loop JIANG Donglei1, MA Xiaowei2, 3, ZENG Chunmin1, LI Fengqing3, LI Wentuo1, ZHANG Xiaodong3, JIA Juncai1 Ocean Engineering Equipment and Technology    2024, 11 (4): 8-13.   DOI: 10.12087/oeet.2095-7297.2024.04.02 Abstract （198）      PDF（pc） （5181KB）（58）       Knowledge map    Save Chemicals such as methanol and ethylene glycol can prevent the formation of hydrates， waxing and scaling within subsea production systems， playing a crucial role in flow assurance. Subsea Chemical Injection Metering Valve (CIMV) is used to control and measure the injected chemicals into subsea production systems. It aids in achieving precise ondemand injection as well as cost reduction and efficiency increase. The structure and measurement principle of CIMV differ significantly from conventional flow meters， hence rigorous calibration is required to ensure the measurement accuracy meeting the design requirements. Based on the product characteristics of CIMV， this paper introduces the design and construction of the first domestic CIMV calibration loop， and discusses how to use this loop to study and build a selfdeveloped CIMV measurement algorithm model. The measurement accuracy of CIMV is verified on this loop， with results as good as ±3% F.S. (Full Scale). This paper provides a valuable reference for the localization of CIMV. Related Articles | Metrics | Comments（0）

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Research on AUV Path Planning Method Based on Deep Sea Multi-Target Search Mission XU Chunhui1, 2, ZHOU Shihao1, 2, 4, QI Yu1, 2, FANG Tian1, 2, 3, YANG Shilin1, 2, 3 Ocean Engineering Equipment and Technology    2024, 11 (4): 95-102.   DOI: 10.12087/oeet.2095-7297.2024.04.15 Abstract （185）      PDF（pc） （4652KB）（223）       Knowledge map    Save Autonomous underwater robots (AUVs) can perform tasks such as resource exploration and target search in deep sea areas. At offshore sites, we often face the need to quickly respond to mission deployment and conduct path planning for AUV search and mapping missions. This paper proposes an AUV multi-target search method that clusters first and then searches in the AUV multi-suspect target point search task. It performs K-means clustering on multiple target points in the large-scale sea area to be measured to form multiple target points to be tested. The measurement area reduces the search for non-target areas and ensures higher search efficiency when the AUV carries limited energy; the comb path scheme is implemented in multiple areas to be measured to form an AUV search path in multiple areas. An AUV multi-target clustering search software based on Tkinter was developed to implement the method proposed in this article through visual interactive tools, solving the problems of time-consuming and error-prone manual planning and improving the efficiency of AUV deployment. Finally, We compare the length of AUV paths between different cluster numbers to determine the feasibility and application value of this method. Related Articles | Metrics | Comments（0）

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Multibody Coupled Dynamics Analysis of the Dual Vessel Float-over Method for Wind Turbine Installation System ZHANG Ningbo1, AN Chen1, ZHAO Tianfeng1, GAO Songlin1, NI Haocheng1, ZHOU Zhenyu2 Ocean Engineering Equipment and Technology    2024, 11 (4): 58-66.   DOI: 10.12087/oeet.2095-7297.2024.04.10 Abstract （182）      PDF（pc） （7736KB）（23）       Knowledge map    Save In order to deal with the vibration and stress of key components caused by ship movement when installing wind turbines on double-ship float supports， this paper proposes a rigid-flexible coupling multi-body dynamics analysis method for load transfer during wind turbine installation. A rigid-flexible coupled multi-body dynamic model for the twinbarge float-over wind turbine installation was developed， considering the elastic deformation of key components and its impact on the overall system. Dynamic analysis of the installation and docking process of the wind turbine and foundation was performed， calculating acceleration and stress curves of the wind turbine and key components under various working conditions. The dynamic stress results and vibration characteristics were investigated， revealing that changes in the twin-barge motion period significantly affect the variation pattern of the wind turbine's stress curve. This study provides a theoretical basis for the structural design of the twin-barge float-over wind turbine installation system， contributing to improved stability and safety during the installation process. Related Articles | Metrics | Comments（0）

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China‘s First DP-3 Closed Ring Power System Design of Engineer Ship XU Aijin, XU Weiping, HAN Xuyan Ocean Engineering Equipment and Technology    2024, 11 (3): 36-41.   DOI: 10.12087/oeet.2095-7297.2024.03.06 Abstract （180）      PDF（pc） （4502KB）（131）       Knowledge map    Save In response to a leading vessel design requirement that cooperating DP-3 closed ring power system, this paper introduce an optimize design of a new deep-water diving support vessel of Shanghai Salvage Bureau from the analysis of the thruster configuration, electric load balance and single line diagram, combined with the DP capability assessment. Then, we divide the overall structure and equipment redundancy grouping of the vessel’s closed ring power station on account of “three-engine rooms, four-DP zones” design. Meanwhile, this paper discusses the design of dual feeding power supply for a special separated switchboard and the protection logic during closed ring operation. Related Articles | Metrics | Comments（0）

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Experimental Analysis of Dropping Motion Characteristics of Hall Anchor in Water SUN Yongqiang, LI Ruibin, WANG Wenkai, FAN Lianming Ocean Engineering Equipment and Technology    2024, 11 (3): 31-35.   DOI: 10.12087/oeet.2095-7297.2024.03.05 Abstract （176）      PDF（pc） （2808KB）（34）       Knowledge map    Save The settlement characteristics of anchor in water, such as drag coefficient, equilibrium depth and equilibrium velocity, are of great significance to the calculation of anchorage force, the analysis of ship stability and the design of buried depth of submarine pipe and cable. In this paper, an empirical formula for calculating the drag coefficient of the Hall anchor when it falls freely in water is proposed through theoretical analysis and physical model test. The results show that it has an exponential function relationship with water depth and anchor mass. For the anchors of representative ship types corresponding to different channels, the minimum equilibrium depth is greater than the channel depth, and the actual touchdown velocity in the channel will be less than the equilibrium velocity. Related Articles | Metrics | Comments（0）

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Research on Development of Suction Bucket Foundation Technology in China Based on Patent Analysis MA Tianchi1, ZHENG Yuan2, NIU Guoxu3, CAO Minghe4 Ocean Engineering Equipment and Technology    2024, 11 (4): 21-28.   DOI: 10.12087/oeet.2095-7297.2024.04.04 Abstract （175）      PDF（pc） （4204KB）（29）       Knowledge map    Save In order to fill the gap in patent analysis of suction bucket foundation technology in China， this article analyzes the overall development trend， patent types and effectiveness， technology development stages， regional distribution， innovation entities， and hot areas of patent technology by using the method of bibliometrics that based on relevant patent data. The analysis results show that the patent technology of suction bucket foundation in China is in a rapid growth stage， with a high proportion of effective patents and nearly 60% of invention patents. The patent application areas are mainly concentrated in economically developed coastal areas， and the overall trend of regional development is from north to south. The proportion of enterprises among applicants is the highest， and hot technology fields are highly concentrated. In the future， the development of patent technology in China should focus on improving patent quality， balancing regional development， improving the cooperation of industryuniversityacademy， expanding the application fields of technology， and improving the rationality of technology field layout. Related Articles | Metrics | Comments（0）

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Anomaly Detection of Environmental Features Based on LSTM-Reconstructed Data ZHOU Lei1, SU Xin2, ZHANG Qi2, HUANG Yi2 Ocean Engineering Equipment and Technology    2024, 11 (4): 1-7.   DOI: 10.12087/oeet.2095-7297.2024.04.01 Abstract （175）      PDF（pc） （5649KB）（157）       Knowledge map    Save With the advancement of environmental monitoring technologies， accurately identifying anomalies in data has become a crucial challenge. This study introduces a method combining Long Short-Term Memory (LSTM) networks and Random Forest models for predicting and reconstructing environmental feature data， thereby enabling effective anomaly monitoring. Initially， the LSTM model is used to forecast time series data for environmental features such as wind speed and direction. Subsequently， these forecasts are used as inputs to apply a Random Forest model for predicting axial force. The research indicates that by reconstructing features， the accuracy of axial force predictions can be significantly enhanced compared to direct anomaly detection methods. The R2 values， Mean Absolute Error (MAE)， and Root Mean Squared Error (RMSE) for data with reconstructed features surpass those for data with original features. Particularly， the improvement from an R2 value of 0.921 to 0.956 underscores a significant enhancement in the model's data fitting capability. Related Articles | Metrics | Comments（0）

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Research on Development and Adaptability of Subsea Compressor Boosting Technology MENG Yao, HOU Guangxin, LIU Weibin, LIU Yongfei Ocean Engineering Equipment and Technology    2024, 11 (3): 57-62.   DOI: 10.12087/oeet.2095-7297.2024.03.09 Abstract （173）      PDF（pc） （3494KB）（107）       Knowledge map    Save The wellhead pressure of the subsea trees could be reduced dramatically by using subsea compressor technology, thereby increasing the production of the target gas field and achieving better economic benefits. The subsea compressor boosting technology has been increasingly valued and favored by domestic and foreign oil companies in recent years. This paper study on the development of the subsea compressor boosting technology and compare the technology roadmap of different subsea compressor to determine better solution for projects in Nanhai Sea in order to provide reference for future potential subsea compressor boosting project. Related Articles | Metrics | Comments（0）