Current Issue

2022, Volume 17,  Issue 5

2022, 17(5): 1-2.
Ship Design and Performance
Thoughts on development of modern ship technology
ZHU Yingfu, XIONG Zhiguo, YUAN Yi, HU Yulong
2022, 17(5): 1-8. doi: 10.19693/j.issn.1673-3185.02928
With the continuous innovation of new maritime concepts of operations, the modern form of naval warfare presents the characteristics of multi-domain attack and defense, distributed coordination and efficient killing, accelerating the innovation and development of new surface ship technology. Focusing on combat space, combat system structure, combat units and combat armaments, this paper summarizes the main characteristics of new modern maritime concepts of operations, categorizes the system positioning and combat capability evolution of surface ships, and systematically analyzes the development of new surface ship equipment. It then puts forward several thoughts on the development of surface ship overall integration technology, network information technology, digital intelligence enabling technology, new energy security technology, advanced material technology and environmental protection and energy saving technology.
Technology application and development trend of intelligent unmanned system
WANG Yaonan, AN Guowei, WANG Chuancheng, MO Yang, MIAO Zhiqiang, ZENG Kai
2022, 17(5): 9-26. doi: 10.19693/j.issn.1673-3185.02705
Intelligent unmanned system combat is moving from concepts to actual combat applications. The military applications of intelligent unmanned systems are emphasized by focusing on the needs of the combat missions that they will undertake on future battlefields and summarizing the development statuses of land, air and maritime unmanned systems. Aiming at the key problems faced by intelligent unmanned systems and the practical difficulties that will be faced on the battlefield in the future, we analyze the key technologies required for intelligent unmanned systems, including autonomous perception and understanding in complex environments, behavioral decision-making and trajectory planning, autonomous navigation and positioning, multi-scenario autonomous skill learning and intelligent control, unmanned cluster cooperative control, natural human-computer interaction, etc. At the same time, aiming at the problems that will be encountered in the further development of intelligent unmanned systems on the battlefield in the future, we start with individual enhancement and cluster enhancement, and conduct a detailed analysis of the development trends of intelligent unmanned systems.
Development trend and key technologies of autonomous underwater vehicles
SONG Baowei, PAN Guang, ZHANG Lichuan, HUANG Qiaogao, YU Yang, TIAN Wenlong, DONG Huachao, ZHANG Xinhu
2022, 17(5): 27-44. doi: 10.19693/j.issn.1673-3185.02939
In order to promote and guide the development of autonomous underwater vehicles (AUVs) in China, this paper summarizes the research status of AUVs at home and abroad, and puts forward the development trends of serialization, grouping, systematization and large-scale development. Key AUV technologies such as overall multidisciplinary optimal design, structure and material design, power and propulsion, navigation and control, detection and communication are discussed. Finally, development opinions are put forward on how to make better use of AUVs to navigate the oceans and achieve the strategic goals of "ocean entry, ocean exploration and ocean utilization".
Research and development of microwave meta-antenna technology
CHEN Zhi Ning
2022, 17(5): 45-51. doi: 10.19693/j.issn.1673-3185.02889
The development of antenna technology has always been restricted by its essential physical limits, but the advancement of artificial structures with unique electric properties, namely metamaterials, offers great opportunities for improving the performance of existing antenna designs and introducing new functions. This article introduces the concepts of "metamaterials" and "metasurfaces". The design of metasurfaces and metasurface antennas is introduced in detail with the example of the microwave meta-lens. The latest progress in the research and development (R&D) of microwave metantenna technology, namely metamaterial and metasurface based antennas, is then briefly summarized. More importantly, the article offers thoughts on future key topics of microwave meta-antenna R&D.
Research developments in numerical methods of fluid-structure interactions in naval architecture and ocean engineering
ZHANG Guiyong, WANG Shuangqiang, SUN Zhe, XIAO Qihang
2022, 17(5): 52-73. doi: 10.19693/j.issn.1673-3185.02887
It is a challenge to solve complex fluid-structure interaction (FSI) problems through theoretical derivations, whereas numerical simulation provides an effective solution and is widely applied in naval architecture and marine engineering. Based on grid treatment, FSI methods are classified into the body-fitted grid method, non-body-fitted grid method, overset grid method and particle-based method. The research development of these four types of methods is then reviewed. Both the body-fitted grid method and overset grid method can accurately capture the interface and are suitable for high Reynolds number flow problems, and the former is generally employed when structural deformation is considered, while the latter often works well when considering rigid body motion with complex geometric shapes. The non-body-fitted grid method can avoid the mesh update operation to make calculations simpler, and is widely used in the simulation of flow control, development of underwater flexible bionic vehicles and interference of multi-body motion. The particle-based method plays an increasingly important role in simulating strong nonlinear fluid-structure interaction problems involving severe free surface deformation, slamming, explosion, etc. The properties of different FSI problems determine the applicability of different methods. How to select a suitable numerical method and combine the advantages of various methods to develop novel numerical methods that can handle more challenging problems are important development directions for FSI algorithms.
Overview of submarine steering system noise
LIAO Jian, HE Lin, CHEN Zongbin, TAN Xiaopeng
2022, 17(5): 74-84. doi: 10.19693/j.issn.1673-3185.02391
The steering system noise is one of the main noise sources in submarine stealth condition. Combined with the composition of the steering system, the noise source of each component is sorted out systematically, and corresponding vibration and noise reduction design measures are proposed. As the main noise source of the steering system, emphasis is placed on analyzing the noise mechanism of the rudder hydraulic system, which is divided into two categories and six types according to steady state and transient operating conditions. Finally, it is pointed out that the new type electro-hydraulic steering gear, based on direct drive servo control principle, is the future development trend.
Research progress and application of computational method for hydrodynamic noise from air-water interface
YU Lianjie, ZHAO Weiwen, WAN Decheng
2022, 17(5): 85-102. doi: 10.19693/j.issn.1673-3185.02862
Hydrodynamic noise from an air-water interface is often encountered in marine engineering structures. It involves a complex mechanism, various forms of sound sources and many factors affecting the propagation. It interacts with the free surface and is affected by cavitation and water-air-bubble mixed flow, which has a negative impact on the concealment of the ship, giving this line of inquiry strong research significance. This paper introduces a noise calculation method and its applications in terms of free surface noise, cavitation noise and water-air-bubble mixed flow noise respectively, and describes their computational methods and key issues. The solutions currently in use are also introduced. Finally, future research directions are proposed.
Review of research on ship flow field measurement technology
GUO Chunyu, KUAI Yunfei, HAN Yang, XU Peng
2022, 17(5): 103-115. doi: 10.19693/j.issn.1673-3185.02857
The refined description of the flow field information around a ship can provide feedback on the internal essence of the ship's macroscopic hydrodynamic performance from the perspective of the flow mechanism, and high-quality flow field measurement technology is a necessary means of ensuring such a refined description of the flow field. Based on the engineering requirements of ship flow field measurement, the current development status of flow field measurement technology is summarized according to its technical characteristics, and the applications and characteristics of each method are described in detail. The existing flow field measurement methods still have many problems that need to be solved. The exploration of hardware upgrading, technology integration, algorithm optimization, function expansion, data assimilation and machine learning may promote the rapid development of flow field measurement technology in the direction of comprehensiveness, specialization and efficiency.
Development and prospects of key technology for submarine atmospheric environment control
LI Junhua, JIAO Guiping, DENG Hui, CAO Congxiao, LI Fang, MA Qiang
2022, 17(5): 116-124. doi: 10.19693/j.issn.1673-3185.03033
Air regeneration, harmful gas purification and atmospheric composition monitoring are the key technologies of submarine atmospheric environment control systems. After years of development, China has made great progress in such systems, which have developed from ensuring the safety requirements of submariner and equipment operation to ensuring the health of submariner and reliability of system for long-term underwater operation. This paper reviews the development history of submarine atmospheric environment control technologies and introduces their future development prospects. The developers of integrated atmospheric environment control technology should learn from foreign submarine and aerosphere equipment technologies, which aim to support long-term submerged operation and comfort demands, and better adapt to future submarine technology development and evolving mission, in order to constantly enhance the level of submarine cabin air quality of the Chinese navy.
Key technologies of ship remote control system in inland waterways under ship-shore cooperation conditions
MA Feng, CHEN Chen, LIU Jialun, WANG Xuming, YAN Xinping
2022, 17(5): 125-133. doi: 10.19693/j.issn.1673-3185.02896
  Objective  To meet the requirements of remotely controlling ship in curved, narrow and crowded inland waterways, this paper proposes an approach that consists of CNN-based algorithms and knowledge based models under ship-shore cooperation conditions.   Method  On the basis of analyzing the characteristics of ship-shore cooperation, the proposed approach realizes autonomous perception of the environment with visual simulation at the core and navigation decision-making control based on deep reinforcement learning, and finally constructs an artificial intelligence system composed of image deep learning processing, navigation situation cognition, route steady-state control and other functions. Remote control and short-time autonomous navigation of operating ships are realized under inland waterway conditions, and remote control of container ships and ferries is carried out.   Results  The proposed approach is capable of replacing manual work by remote orders or independent decision-making, as well as realizing independent obstacle avoidance, with a consistent deviation of less than 20 meters.   Conclusions  The developed prototype system carries out the remote control operation demonstration of the above ship types in such waterways as the Changhu Canal Shenzhou line and the Yangtze River, proving that a complete set of algorithms with a CNN and reinforcement learning at the core can independently extract key navigation information, construct obstacle avoidance and control awareness, and lay the foundation for inland river intelligent navigation systems.
Research status and control technology of autonomous underwater vehicle variable buoyancy system
LI Ben, HUANG Zhemin, HE Bin, PAN Xingbang, XU Guohua
2022, 17(5): 134-147. doi: 10.19693/j.issn.1673-3185.02856
The application of variable buoyancy systems (VBS) in autonomous underwater vehicles (AUVs) have greatly improved their maneuverability, endurance, adaptability to environmental change and ability to accomplish a variety of tasks. As there are various types of AUVs, the types of VBS are also different. Thus, it is necessary to further research AUV VBS and control technology. First, the principles and characteristics of different types of AUV VBS are explained in detail, and their applicable scenarios summarized. Typical applications of VBS in AUV maneuvering control are then introduced, including balancing, hovering, landing and bottoming. Next, the existing buoyancy adjustment technology, buoyancy observation technology and cooperative maneuvering control technology of AUV VBS are reviewed and evaluated. Finally, the development prospects of AUV VBS are evaluated.
Fuzzy sliding mode control method for vertical motion of autonomous underwater gliders
WAN Lei, ZHANG Dongliang, SUN Yanchao, QIN Hongde, CAO Yu
2022, 17(5): 148-156. doi: 10.19693/j.issn.1673-3185.02521
  Objective  This paper proposes a fuzzy sliding mode controller based on T-S fuzzy logic for the vertical plane motion control of an autonomous underwater glider (AUG) with limited actuator capability.   Methods  In the fuzzy sliding mode controller, the fuzzy switching rate is used to replace the switching rate in the fixed time controller to effectively suppress buffeting. The fuzzy switching rate is obtained by fitting the switching rate of the fixed time controller with T-S fuzzy rules. Based on the limited capabilities of AUG actuators, a saturation auxiliary system is designed to improve the actuator saturation effect. Finally, the performance of the system is verified by Lyapunov stability analysis and numerical simulation.   Results  The results show that the AUG under the fuzzy sliding mode controller and the saturation auxiliary system can converge in finite time. The effectiveness of the fuzzy sliding mode controller and the saturation auxiliary system are verified by numerical simulation.   Conclusions  By making comparisons with the fixed-time controller, it is verified that the two controllers have similar control performance, and the buffeting of the fuzzy sliding mode controller is lesser.
Cooperative path following control of UAV and USV cluster for maritime search and rescue
WANG Haoliang, YIN Chenyang, LU Liyu, WANG Dan, PENG Zhouhua
2022, 17(5): 157-165. doi: 10.19693/j.issn.1673-3185.02916
  Objectives  This paper studies a three-dimensional (3D) cooperative path-following control problem in the process of maritime search and rescue for a heterogeneous unmanned cluster system composed of unmanned aerial vehicles (UAVs) and unmanned surface vehicles (USVs).  Methods  First, kinematic models of the UAVs and USVs are established under a fixed coordinate system and body coordinate system. In order to design a 3D path-following controller suitable for motion control, an air coordinate system is established, and the path tracking error models of the UAVs and USVs are established in the Serret-Frenet coordinate system. Next, a 3D line-of-sight (LOS) guidance law is designed at the kinematic level, and a cooperative path-following control method suitable for heterogeneous clusters of marine vehicles is proposed, allowing the UAVs and USVs to track the preset parameterized path. Finally, the stability of the control system is analyzed based on the Lyapunov stability theory.  Results  The simulation results verify the effectiveness of the proposed cooperative path-following control method for heterogeneous clusters of marine vehicles.  Conclusions  The results of this study can provide references for maritime search and rescue by using the proposed cooperative path-following control method.
Monocular visual servo-based stabilization control of underactuated unmanned surface vehicle
HE Hongkun, WANG Ning
2022, 17(5): 166-174, 183. doi: 10.19693/j.issn.1673-3185.02853
  Objectives  Aiming at the accurate posture stabilization problem of an under-actuated unmanned surface vehicle (USV) in GPS-denied environments, a monocular visual servo stabilization control scheme is proposed based on homography.  Methods  By virtue of the homography decomposition technique, posture errors with an unknown scale factor are directly reconstructed from current and desired images, which thoroughly removes the calibration of extrinsic camera parameters and priori information on visual targets; with respect to the under-actuation constraint, a periodic function to persistently excite the yaw angle is incorporated into the continuous time-variant output feedback controller, allowing the USV to be stabilized in the absence of image depth, movement velocities and model parameters.  Results  Under the framework of the Lyapunov theory, the closed-loop visual servo system of the USV is rigorously proven to be asymptotically stable by Barbalat lemma.  Conclusions  By installing an onboard monocular camera, USV posture errors can be precisely stabilized with the aid of the proposed visual servo strategy, providing significant technique support for practical applications including docking, berthing, dynamic positioning, etc.
Nonlinear observer-based adaptive thruster allocation for thruster fault tolerant control of over-actuated UUV
WANG Guandao, XIANG Xianbo, LI Jinjiang, YANG Shaolong
2022, 17(5): 175-183. doi: 10.19693/j.issn.1673-3185.02571
  Objective  To deal with the external time-variance disturbances and possible failure of actuators during the dynamic positioning operation of an unmanned underwater vehicle (UUV), this paper proposes a nonlinear observer-based adaptive allocation strategy to achieve thruster fault tolerance.   Method  The control scheme is first established by means of the power sliding mode control technique to obtain the dynamic position. Meanwhile, a nonlinear disturbance observer is designed to estimate external disturbances. Then, based on the estimated external disturbance and state deviation sequence under the failure mode, a quadratic programming problem is constructed and solved to obtain the efficiency factor of each thruster, and the thrust distribution matrix is modified to achieve adaptive control allocation under thruster fault tolerance.   Results  The simulation results show that the UUV control system can effectively estimate external environmental disturbances and the efficiency factor of each thruster. Even if the actuator fails, the UUV can still accomplish its dynamic positioning mission.   Conclusion  The results of this study show that the proposed adaptive thruster allocation and sliding mode control algorithm is reasonable and can be effectively applied to UUVs under external environmental disturbances and actuator failure.
Collision avoidance path planning algorithm research and application of medium-sized USV based on COLREGS
WANG Hongdong, YI Hong, XIANG Jinlin, FU Yuewen
2022, 17(5): 184-195, 203. doi: 10.19693/j.issn.1673-3185.02831
  Objective  In order to solve the multi-objective collision avoidance problem of unmanned surface vehicles (USVs) in open waters, this paper takes a medium-sized USV as the object and carries out the research and application exploration of a local path planning algorithm based on the Convention on the International Regulations for Preventing Collisions at Sea (COLREGS).   Methods  A virtual obstacle line method is proposed to load the constraints of COLREGS based on the RRT algorithm for meeting the practical requirements of collision avoidance path planning in open water. In light of the problem that the RRT algorithm does not consider the speed dimension, a velocity obstacle (VO) algorithm is introduced. Next, a VO-RRT fusion algorithm is proposed and given the most dangerous obstacle strategy in order to solve the problem of real-time collision avoidance under multi-objective conditions.   Results  The simulation and real ship test results show that the proposed algorithm has better real-time performance and takes less than 50 ms to undertake path re-planning. The collision avoidance path planned by the algorithm meets the relevant requirements of Articles 6, 8 and 13–18 of COLREGS. The proposed method can effectively deal with the multi-target collision avoidance problem in open waters.   Conclusion  The proposed method has good rule compliance, real-time and safety performance, and high practical value.
Ship resistance in random ice field of small ice floes made of the substitute material
ZONG Zhi, CHEN Zhaoyang
2022, 17(5): 196-203. doi: 10.19693/j.issn.1673-3185.02847
  Objectives  This study focuses on the feasibility of a ship resistance model test in an ice field of small ice floes made of substitute material in order to reveal the resistance components and thereby provide technical support for the design of ice-going ships.   Methods  Ship resistance test in ice floes made of polypropylene (PP) instead of natural refrigerated ice is conducted. By adjusting the sizes, shapes, numbers of ice floes, the random ice field with a given concentration is generated. The geometric phase transition theory predicts that there exists a critical concentration which divides the random ice field into discrete phase (concentration is less than critical value) and connected phase (concentration is greater than critical value).  Results  The main components of ice resistance in the discrete phase are open water resistance and ship-ice collision resistance, while ice resistance in the connected phase includes ice friction resistance, open water friction resistance and collision resistance. If the fractal dimension of the random ice field is used to redefine the ice resistance coefficient, it is nearly constant in the trial range (speed 0.3–0.9 m/s) when the concentration is smaller than the critical value. When the concentration is greater than the critical value, the ice friction resistance is inversely proportional to speed.   Conclusions  Polypropylene can replace frozen ice in the prediction of ice resistance. The pure ice resistance of an ice field is divided into two components: ice resistance arising from collision and ice friction resistance arising from accumulation.
Influence of slip boundary on flow separation and drag of flow past bluff body at high Reynolds numbers
CHEN Wei, LENG Wenjun, HE Peng, WANG Lei
2022, 17(5): 204-211. doi: 10.19693/j.issn.1673-3185.02935
  Objectives  Flow separation increases the drag and noise of underwater vehicles, and influences the controllability of their control surfaces. Therefore, the influence of slip caused by superhydrophobic surfaces on drag reduction and flow separation is studied.   Methods  A partial slip boundary condition is developed, and the flow around a circular cylinder and foil with a slip boundary at high Reynolds numbers are numerically simulated.   Results  The results show that the when the slip length increases, the flow around the cylinder goes through three stages: the turbulent Kármán vortex street, laminar Kármán vortex street and non-separation Stokes flow. The drag coefficient increases first and then decreases, and the vortex shedding frequency increases. For flow around a foil, the separation position moves downstream until the separation region disappears when the slip length increases, and the drag coefficient decreases while the lift coefficient increases.   Conclusions  The results of this study show that for flow past bluff body at high Reynolds number, the slip boundary can control flow separation and reduce drag effectively, providing technical support for the application of superhydrophobic surfaces for the flow control of underwater vehicle appendages.
Ship Structure and Fittings
Structural design considerations for ships operating in arctic regions
2022, 17(5): 212-219. doi: 10.19693/j.issn.1673-3185.02979
The safety of Arctic ships will be influenced by the interactions with ice ridges and icebergs. Generally, the structural design loads will be governed by these ice features. In order to design ship structures, the principles of risk-based design should be considered and followed. The following limit state design criteria are usually applied in structural design: 1) Serviceability Limit States (SLS); 2) Ultimate Limit States (ULS); 3) Fatigue Limit States (FLS); 4) Abnormal/Accidental Limit States (ALS). The ULS and ALS correspond to impact events with a very low probability to occur, and its intention is to ensure that a ship hull structure does not suffer from a complete loss of integrity. However, for analysis of the ice loads with low probability levels, the number of relevant load cases is significant and the computation amount is huge. In this work, the so-called environmental contour method is introduced in order to reduce the required number for ice loads analysis as well as to identify the most likely combinations of the relevant design parameters. Utilization of this approach is illustrated in connection with the ULS and ALS in the present paper. Application of the proposed method could be a valuable supplementary for structural design of Arctic ships.
Analysis on acoustic performance of floating raft vibration isolation system with liquid tank
LEI Zhiyang, DU Kun, WU Chongjian, CHEN Zhigang, YAN Xiaojie, LIU Jun
2022, 17(5): 220-227. doi: 10.19693/j.issn.1673-3185.02574
  Objective  This paper aims to establish a dynamic model of a floating raft vibration isolation system with a liquid tank in order to study the mass effect of the liquid medium, tank form, structural stiffness and loading rate on acoustic performance.   Methods  A floating raft system with a cuboidal or cylindrical liquid tank is taken as the research object, and a fluid-structure coupling finite element dynamic model is established. The dynamic force transmission rate and power flow are then used to evaluate the acoustic performance of the system. The influence of the mass effect of the liquid medium, tank form, structural stiffness and loading rate of tank volume on the acoustic performance of the floating raft system are analyzed.  Results  The results show similar laws obtained through the calculation and analysis of the floating raft system with two types of tanks. The structural stiffness of the tank affects the mass effect of the liquid medium in the tank to a certain extent.   Conclusions  If full advantage is to be taken of the liquid mass effect in the tank with a large loading rate to improve the acoustic performance of the floating raft system, the design of the liquid tank and raft structure must have sufficient stiffness. In addition, under the condition that the floating raft structure has sufficient stiffness, its acoustic performance will improve significantly as the tank loading rate increases in the relevant low frequency range.
Numerical analysis of transient fluid-structure interaction of warship impact damage caused by underwater explosion using the FSLAB
LIU Yunlong, WANG Pingping, WANG Shiping, ZHANG Aman
2022, 17(5): 228-240. doi: 10.19693/j.issn.1673-3185.02865
  Objectives  This paper aims to address the numerical simulation problems of the dynamic response of ships subject to near-, medium- and far-field underwater explosions by establishing several numerical methods and calculation models.   Methods  First, load and fluid-structure interaction models are established on the basis of the Eulerian finite element method and acoustic finite element method using the field-split technique, and FSLAB fluid-structure interaction software is developed. Next, near-, medium- and far-field underwater explosions are numerically simulated respectively. The shock wave propagation law, bubble shape and load evolution characteristics of near free-surface and near-wall underwater explosions are obtained, and the shock response characteristics of a spherical shell and ship subject to far-field underwater explosions are analyzed. Finally, the FSLAB software results are compared with the analytical solutions, reference solutions and experimental data.   Results  The results show that the FSLAB fluid-structure interaction software developed in this paper is effective and accurate in simulating the impact damage of underwater explosions on warships.   Conclusion  This study can provide a basis and support for the power assessment of underwater anti-explosion and shock design of warships.
Numerical calculation of coupled damage effects on ship subjected to internal blast loading of warhead
ZHOU Hu, YUE Xuesen, KONG Xiangshao, ZHENG Cheng, WU Weiguo
2022, 17(5): 241-249, 267. doi: 10.19693/j.issn.1673-3185.02917
  Objective  This paper studies the coupled damage effects of a ship's structure due to the internal blast loading of a warhead.   Methods  Blast tests with cased charge data are conducted to verify the effectiveness of the coupled SPH-FEM approach, and numerical calculations are then performed on real ship compartment scale model tests to analyze the coupled fragmentation and shockwave damage effects of an explosion in a confined cabin.  Results  The results show that the fragments caused by the detonation of the warhead will first cause local damage to the cabin structure. The shockwave will exacerbate the local damage, and blasted openings will further increase the space for the propagation and diffusion of the shockwave inside the chamber, which will in turn cause damage to the adjacent structures. The simple equivalence of the warhead to a bare charge does not give a true picture of the effect of the warhead on the ship's structure, and fragmentation plays a significant role in the detonation of the warhead.  Conclusions  The results of this study show that employing the coupled SPH-FEM numerical method to calculate the coupling damage effects on a ship's structure can accurately reproduce the warhead damage pattern in tests, thereby providing support for the improved assessment of the damage of naval structures under warhead detonation.
Parameter optimization and parametric deviation influence for shock resistance of double-stage vibration isolation system with limiters
GU Yongpeng, WANG Xiaoxin, WANG Hongtao, LI Xiaotian
2022, 17(5): 250-256. doi: 10.19693/j.issn.1673-3185.02978
  Objectives  For marine nuclear power plants, the relative displacement of the pump supported by a vibration isolation system should be strictly restricted. In order to improve the shock resistance of a vibration isolation system with displacement limiters, the parameter optimization and parametric deviation influence are studied.   Methods  The theoretical model of a double-stage vibration isolation system with typical limiter parameters is established, the analysis of the shock response characteristics of the system is carried out using the direct integration method, the optimal limiter parameters are obtained using a genetic algorithm, and the influence of parameter deviation on the shock resistance of the system is studied.   Results  Limiter parameters significantly affect the shock response characteristics of the vibration isolation system. The optimal limiter parameters improve the shock resistance of the system, but parameter deviation has a great influence on shock resistance. Based on the influence of parameter deviation, a deviation control strategy is proposed in which the elastic parameter should have a positive deviation and the gap parameter a negative deviation. The simulation results show that the proposed strategy can effectively alleviate the shock resistance degradation caused by deviation.  Conclusions  The results of this study can be used to guide the design, manufacturing and variation control of limiters for vibration isolation systems.
Marine Machinery, Electrical Equipment and Automation
Analysis of the application and development of integrated electric power technology for unmanned ships
WANG Dong, JI Feng, AI Sheng, HU Pengfei, LIU Zhixin, MEI Dan
2022, 17(5): 257-267. doi: 10.19693/j.issn.1673-3185.03027
With the constant development of power, information and other technologies, the advantages of unmanned ships are emerging in anti-mine, anti-submarine, electronic warfare, maritime security, maritime interception, and other military fields. This paper describes the development of unmanned ships and power technology and clarifies that the integrated power system has become a major trend of medium and large-sized unmanned ships. It also introduces the application of integrated power system in manned and unmanned platforms, and proposes that issues like size, weight, and control of vibration and noise are of essential for the integrated power system for unmanned platforms. In the end, this paper summarizes the trend of integrated power technology for unmanned platforms and identifies the key scientific problems of integrated power technology on unmanned platform, namely the intelligent operation of integrated power system, high-performance motor materials, information perception of complex motor system, power electronic device and system, high-performance power conversion and efficient energy storage.
Asymmetric regular sampling SPWM method based on tangent-secant midpoint approximation applied to intermediate frequency inverter power supply
LI Weibo, FANG Peng, PAN Junfeng, HAO Chunhao, ZHANG Zhongtian
2022, 17(5): 268-277, 288. doi: 10.19693/j.issn.1673-3185.02815
  Objective  In order to reduce the switching frequency of an intermediate frequency inverter power supply, ensure the quality of the output waveform and realize digitalization easily, a SPWM sampling method based on a tangent-secant midpoint approximation is proposed.   Methods  It is proven by deduction that the quantitative relationship of the natural sampling method can be approximated, and a Matlab/Simulink simulation model is built. The algorithm is designed and applied to an intermediate frequency inverter device, and the correctness of the proposed method is verified in the two aspects of simulation and experiment.   Results  The simulation results show that the total harmonic distortion (THD) of the output waveform based on the tangent-secant midpoint approximation method is 2.64%, lower than the 3.99% of the symmetrical regular sampling method. The waveform quality of the tangent-secant midpoint approximation method is obviously better than that of the symmetrical regular sampling method, as it not only reduces the switching frequency but also takes into account the requirements of THD.   Conclusions  SPWM sampling based on tangent-secant midpoint approximation is applied to the intermediate frequency power supply and is able to effectively overcome the shortcomings of the low-quality output waveform and high switching frequency of the symmetrical regular sampling method. Both theoretical analysis and engineering practice verify the rationality and correctness of the proposed method, and it can be widely extended to the field of intermediate frequency power supply installation.
Experimental research on dynamic responses characteristics and influence laws of gear transmission-propulsion system under gear excitation
HUANG Zhiwei, CHEN Yanqi, LEI Zhiyang, HUANG Xiuchang, PENG Weicai, HUA Hongxing
2022, 17(5): 278-288. doi: 10.19693/j.issn.1673-3185.02852
  Objective  In order to study the dynamic response characteristics and influence laws of a marine gear transmission-propulsion system, a series of bench tests is carried out.  Methods  First, a biaxial gear transmission-propulsion system test bench including a cross connection gear is built. Experiments to test the acceleration response of the gearbox body and propulsion shaft system are then carried out, and the influence of speed, driving mode, axial static thrust, axial dynamic excitation force from the propeller and other factors on the dynamic response characteristics of the system are compared and analyzed.   Results  The experimental results show that the transmission law of the vibration acceleration response of the gear transmission-propulsion system is mainly at the meshing frequency and its multipliers, as well as peaks in the low frequency band of 30–80 Hz under certain working conditions.   Conclusion  This study can provide technical support for the vibration and noise reduction design of gear transmission-propulsion systems.
Fault diagnosis of marine diesel engines based on graph convolutional network under unbalanced datasets
WANG Ruihan, CHEN Hui, GUAN Cong, HUANG Mengzhuo
2022, 17(5): 289-300. doi: 10.19693/j.issn.1673-3185.02859
  Objectives  The class imbalance problems which are prevalent in the condition monitoring data of marine diesel engines significantly deteriorate the performance of data-driven models for the automatic and accurate identification of the health condition of engines. In this paper, a graph convolutional network (GCN) model based on probability similarity between samples is proposed to solve the classification problem of unbalanced datasets.   Methods  First, the Kullback-Leibler divergence is introduced to calculate the probability similarity between samples and mine the nonlinear relationship, and a probability topological graph is constructed to represent the similarity of samples. Graph learning is then introduced to learn and extract the correlations between adjacent samples in addition to their own features, providing more information for the imbalanced classification task. After multi-layer graph learning, the higher-level features of each node are extracted.  Results  The two cases of the simulation model and bench test clearly show that the proposed method efficiently extracts more information based on aggregating neighboring samples'features, and improves the classification accuracy under imbalanced datasets.   Conclusions  The precision and recall rate of the proposed GCN model are higher than those of other state-of-the-art algorithms, giving it certain practical application value.
Weapon, Electronic and Information System
Development and prospects of initial alignment method for strap-down inertial navigation system
LUO Li, HUANG Yulong, CHANG Lubin, ZHANG Yonggang
2022, 17(5): 301-313. doi: 10.19693/j.issn.1673-3185.02884
Initial alignment technology is directly related to the navigation accuracy and startup time of the strap-down inertial navigation system (SINS), and has always been regarded as a challenging focal point in the research field of inertial navigation. This paper makes a comprehensive survey of SINS initial alignment technology, briefly introduces the basic principles of initial alignment without latitude, coarse alignment with known latitude and precise alignment, and points out their advantages, disadvantages and applicable conditions. The research and effects of existing initial alignment error suppression techniques are then analyzed and discussed. Finally, according to the problems of existing initial alignment methods and the development requirements of the carrier, the future research direction of SINS initial alignment technology is predicted.
Modeling design of military equipment operational concepts by MBSE
DONG Xiaoming, HAN Yan, WANG Zhisong, WANG Wenyun
2022, 17(5): 314-322. doi: 10.19693/j.issn.1673-3185.02891
  Objectives  In order to give full play to role of "operational concepts" in the engineering process of military equipment development, it is necessary to understand and form standardized operational concept documents (OCD), and study the modeling design of OCD in order to implement the transformation of the system engineering process from document-centric to model-centric.   Methods  This study analyzes the US military's definition of operational concepts and introduces its hierarchical operational concepts, especially the bottom level ConOps or OpsCon, usually as a part of equipment acquisition and requirement engineering. Lessons are then drawn from the relevant theories and standards such as IEEE 29148:2018 and ANSI/AIAA G-043B-2018 of the operational concepts document outline in order to design the specifications of the OCD. Finally, key technologies are studied, including SysML-based OpsCon modeling, UML Profile-based OpsCon framework design and MSDL/C-BML-based operational scenario development.  Result  The results indicate the effectiveness of implementing the modeling design of OCDs.   Conclusions  In the process of equipment requirement engineering, the results of this study can help to improve the efficiency of equipment requirement demonstration through an ambiguous operational concept model and an engineering environment for all stakeholders of the system.