Optimization of jamming formation of USV offboard active decoy clusters based on an improved PSO algorithm

Offboard active decoys(OADs)can effectively jam monopulse radars.However,for missiles approaching from a particular direction and distance,the OAD should be placed at a specific location,posing high requirements for timing and deployment.To improve the response speed and jamming effect,a cluster of OADs based on an unmanned surface vehicle(USV)is proposed.The formation of the cluster determines the effectiveness of jamming.First,based on the mechanism of OAD jamming,critical conditions are identified,and a method for assessing the jamming effect is proposed.Then,for the optimization of the cluster formation,a mathematical model is built,and a multi-tribe adaptive particle swarm optimization algorithm based on mutation strategy and Metropolis criterion(3M-APSO)is designed.Finally,the formation optimization problem is solved and analyzed using the 3M-APSO algorithm under specific scenarios.The results show that the improved algorithm has a faster convergence rate and superior performance as compared to the standard Adaptive-PSO algorithm.Compared with a single OAD,the optimal formation of USV-OAD cluster effectively fills the blind area and maximizes the use of jamming resources.

Online task planning method of anti-ship missile based on rolling optimization

Based on the wave attack task planning method in static complex environment and the rolling optimization framework, an online task planning method in dynamic complex environment based on rolling optimization is proposed. In the process of online task planning in dynamic complex environment,online task planning is based on event triggering including target information update event, new target addition event, target failure event, weapon failure event, etc., and the methods include defense area reanalysis, parameter space update, and mission re-planning. Simulation is conducted for different events and the result shows that the index value of the attack scenario after re-planning is better than that before re-planning and according to the probability distribution of statistical simulation method, the index value distribution after re-planning is obviously in the region of high index value, and the index value gap before and after re-planning is related to the degree of posture change.

Robust optimal dispatch strategy of integrated energy system considering CHP-P2G-CCS

Integrated energy systems(IESs)can improve energy efficiency and reduce carbon emissions,essential for achieving peak carbon emissions and carbon neutrality.This study investigated the characteristics of the CHP model considering P2G and carbon capture systems,and a two-stage robust optimization model of the electricity-heat-gascold integrated energy system was developed.First,a CHP model considering the P2G and carbon capture system was established,and the electric-thermal coupling characteristics and P2G capacity constraints of the model were derived,which proved that the model could weaken the electric-thermal coupling characteristics,increase the electric power regulation range,and reduce carbon emissions.Subsequently,a two-stage robust optimal scheduling model of an IES was constructed,in which the objective function in the day-ahead scheduling stage was to minimize the start-up and shutdown costs.The objective function in the real-time scheduling stage was to minimize the equipment operating costs,carbon emission costs,wind curtailment,and solar curtailment costs,considering multiple uncertainties.Finally,after the objective function is linearized with a ψ-piecewise method,the model is solved based on the C&CG algorithm.Simulation results show that the proposed model can effectively absorb renewable energy and reduce the total cost of the system.

The measure and decision of technical risk in the development of naval vessels

The risks in development of navy vessels were explored. The resources of technical risk in the design and development of vessels were mentioned. It was pointed that technical risk dominated the other risk components. Based on the writers' understanding and experience from risk analysis and risk management to the development of a navy vessel, four measure indexes of technical risk were presented. The decision criteria and the rules corresponding to the indexes were established by the statistic information.

Sagging damage characteristics of hull girder with trapezoidal cross-section subjected to near-field underwater explosion

To investigate the overall damage characteristics and failure modes of a warship subjected to an underwater non-contact near-field explosion,a hull girder with a trapezoidal cross-section was designed,manufactured,and tested.The design criteria and parameters were determined according to the similarity criterion.Dynamic responses of the girder freely floating on water were obtained under varying conditions,including stand-off distance,charge mass,and position of attack.Damage morphologies of the girder model were obtained.Based on our analysis,basic conditions for sagging damage of the hull girder are proposed.The aim of this study was to determine an efficient method of attack resulting in the most severe damage to the ship hull.The experimental results show that the girder mainly exhibits a first-order response when the first wet frequency of the girder is close to the frequency of the explosion bubble pulsation.The largest deformation was observed when the underwater explosion occurred directly below the midspan of the girder compared to other explosions of the same intensity at different attack positions.When the ratio of stand-off to maximum bubble radius(λ)satisfies 0.7≤λ<2,the bubble mainly causes sagging damage instead of hogging.Asλdecreases(1≤λ<2),the sagging damage increases under the same charge mass.However,asλdecreases further(0.7≤λ<1),the sagging deformation decreases.This is likely due to the impact of the liquid jet formed by the collapsing bubble,which causes the girder deformation to shift from sagging back to hogging deformation.The initial shock wave excites the high-frequency response of the girder structure but contributes very little to the overall velocity and displacement.However,bubble pulsation typically causes a low-frequency response,which will affect the velocity and displacement of the girder.The low-pressure region of the flow field formed by bubble pulsation and resonant coupling between the girder and the bubble are the predominant causes of damage to the overall girder structure.

LSTM-DPPO based deep reinforcement learning controller for path following optimization of unmanned surface vehicle

To solve the path following control problem for unmanned surface vehicles(USVs),a control method based on deep reinforcement learning(DRL)with long short-term memory(LSTM)networks is proposed.A distributed proximal policy opti-mization(DPPO)algorithm,which is a modified actor-critic-based type of reinforcement learning algorithm,is adapted to improve the controller performance in repeated trials.The LSTM network structure is introduced to solve the strong temporal cor-relation USV control problem.In addition,a specially designed path dataset,including straight and curved paths,is established to simulate various sailing scenarios so that the reinforcement learning controller can obtain as much handling experience as possible.Extensive numerical simulation results demonstrate that the proposed method has better control performance under missions involving complex maneuvers than trained with limited scenarios and can potentially be applied in practice.

Design and analysis of a scheme for the naval gun test shell entering the bore

The test shell without projectile belt is widely used in the teaching,inspection and maintenance of modern automatic naval guns.In order to ensure the normal work of each mechanism,it is very important to design the buffer and limit of the test shell during the process of entering the bore.Taking a certain type of medium caliber naval gun as the research object,the design of colloidal fluid damper and cartridge lock was proposed to ensure the reliability of entering the bore and closing the breechblock.By combining the simulation methods of computational fluid dynamics(CFD)and multibody system dynamic(MBD),it was analyzed whether the structural design can meet the engineering requirements.The research results show that the colloidal fluid damper can dissipate a large amount of kinetic energy of the shell,and the cartridge lock can limit the rebound movement.The combination of the two ensures the smooth process of closing the breechblock.The research provides a design method for the process of the test shell entering the bore,and provides theoretical support for the feasibility of the method.

Cooperative trajectory optimization of UAVs in approaching stage using feedback guidance methods

This paper mainly studies the problem of using UAVs to provide accurate remote target indication for hypersonic projectiles.Based on the optimal trajectory trends and feedback guidance methods,a new cooperative control algorithm is proposed to optimize trajectories of multi-UAVs for target tracking in approaching stage.Based on UAV kinematics and sensor performance models,optimal trajectory trends of UAVs are analyzed theoretically.Then,feedback guidance methods are proposed under the optimal observation trends of UAVs in the approaching target stage,producing trajectories with far less computational complexity and performance very close to the best-known trajectories.Next,the sufficient condition for the UAV to form the optimal observation configuration by the feedback guidance method is presented,which guarantees that the proposed method can optimize the observation trajectory of the UAV in approaching stage.Finally,the feedback guidance method is numerically simulated.Simulation results demonstrate that the estimation performance of the feedback guidance method is superior to the Lyapunov guidance vector field(LGVF)method and verify the effectiveness of the proposed method.Additionally,compared with the receding horizon optimization(RHO)method,the proposed method has the same optimization ability as the RHO method and better real-time performance.

Fine-Grained Classification of Remote Sensing Ship Images Based on Improved VAN

The remote sensing ships’fine-grained classification technology makes it possible to identify certain ship types in remote sensing images,and it has broad application prospects in civil and military fields.However,the current model does not examine the properties of ship targets in remote sensing images with mixed multi-granularity features and a complicated backdrop.There is still an opportunity for future enhancement of the classification impact.To solve the challenges brought by the above characteristics,this paper proposes a Metaformer and Residual fusion network based on Visual Attention Network(VAN-MR)for fine-grained classification tasks.For the complex background of remote sensing images,the VAN-MR model adopts the parallel structure of large kernel attention and spatial attention to enhance the model’s feature extraction ability of interest targets and improve the classification performance of remote sensing ship targets.For the problem of multi-grained feature mixing in remote sensing images,the VAN-MR model uses a Metaformer structure and a parallel network of residual modules to extract ship features.The parallel network has different depths,considering both high-level and lowlevel semantic information.The model achieves better classification performance in remote sensing ship images with multi-granularity mixing.Finally,the model achieves 88.73%and 94.56%accuracy on the public fine-grained ship collection-23(FGSC-23)and FGSCR-42 datasets,respectively,while the parameter size is only 53.47 M,the floating point operations is 9.9 G.The experimental results show that the classification effect of VAN-MR is superior to that of traditional CNNs model and visual model with Transformer structure under the same parameter quantity.

Strategy dominance mechanism of autonomous collaboration in unmanned swarm within the framework of public goods game

The key advantage of unmanned swarm operation is its autonomous cooperation. How to improve the proportion of cooperators is one of the key issues of autonomous collaboration in unmanned swarm operations. This work proposes a strategy dominance mechanism of autonomous collaboration in unmanned swarm within the framework of public goods game. It starts with the requirement analysis of autonomous collaboration in unmanned swarm;and an aspiration-driven multiplayer evolutionary game model is established based on the requirement. Then the average abundance function and strategy dominance condition of the model are constructed by theoretical derivation. Furthermore, the evolutionary mechanism of parameter adjustment in swarm cooperation is revealed via simulation,and the influences of the multiplication factor r, aspiration levelα, threshold m and other parameters on the strategy dominance conditions were simulated for both linear and threshold public goods games(PGGs) to determine the strategy dominance characteristics;Finally, deliberate proposals are suggested to provide a meaningful exploration in the actual control of unmanned swarm cooperation.

Speed Identification of Speed Sensorless Linear Induction Motor Based on MRAS

In the linear induction motor control system,the optical grating speed transducer is susceptible to strong magnetic field interference.What's more,it may reduce motor integration and raise device costs.Therefore a speed identification method to replace grating speed transducer is studied in this article.This speed identification method for linear induction motor mainly adopts Model Reference Adaptive Method(Abbreviated as MRAS)and Popov Hyperstability Theory.The research content of this paper can be divided into four parts.First,the mathematical model of the motor based on the model reference adaptive system structure is deduced.Second,the adaptive law of the estimated speed is solved by Popov hyper-stability theory,which ensures the stability of the system.Third,the simulation model of the linear induction motor speed identification control system based on model reference adaptation is built in the MATLAB environment.Finally,the simulation test and analysis are carried out.The simulation results show that the speed identification control system can track the actual speed of the linear induction motor well in the no-load operation and the load operation,and the stability of the system is guaranteed in the full speed range.

Iron/aluminum nanocomposites prepared by one-step reduction method and their effects on thermal decomposition of AP and AN

Aluminum(Al)powder is widely used in solid propellants.In particular,nano-Al has attracted extensive scholarly attention in the field of energetic materials due to its higher reactivity than micro-Al.However,the existence of aluminum oxide film on its surface reduces the heat release performance of the aluminum powder,which greatly limits its application.Hence,this paper used iron,a component of solid propellant,to coat micron-Al and nano-Al to improve the heat release efficiency and reactivity of Al powder.SEM,TEM,EDS,XRD,XPS,and BET were used to investigate the morphological structure and properties of pure Al and Fe/Al composite fuels of different sizes.The results show that Fe was uniformly coated on the surface of Al powder.There was no reaction between Fe and Al,and Fe/Al composite fuels had a larger specific surface area than pure Al,which could better improve the reactivity of pure Al.Besides,the catalytic effects of pure Al and Fe/Al composite fuels of different sizes on ammonium perchlorate and ammonium nitrate were explored.The results show that the catalysis of pure Al powder could be greatly improved by coating Fe on the surface of Al powder.Especially,the micron-Fe/Al composite fuel had a higher catalytic effect than the pure nano-Al powder.Hence,Fe/Al composite fuels are expected to be widely used in solid propellants.

Coupler Loss Analysis of Magnetically Coupled Resonant Wireless Power Transfer System

The demand for electric vehicles has increased over the past few years.Wireless power transfer for electric vehicles provides more flexibility than traditional plug-in charging technology.Charging couplers are critical components in wireless power transfer systems.The thermal effect produced by the magnetic coupler in work will cause the temperature of the device to rise rapidly,affecting the work efficiency,transfer power,operation reliability,and service life.This paper modeled and analyzed each component's temperature distribution characteristics and thermal behavior.Firstly,the magnetic coupler's mutual inductance and magnetic circuit model are established,and the thermal model of the magnetic coupler analyzes the heat generation process.The thermal models of the coupler under three different magnetic core distributions are established,and the temperature rise of each component is obtained.The temperature rise of different parts of the coupler is verified by the temperature rise test structure of the experiment.

On the Assessment of Generative AI in Requirements Analysis and Modeling Tasks with UML:An Exploratory Study

Generative AI is rapidly employed by software developers to generate code or other software artifacts.However,the analysis and assessment of generative AI with respect to requirements analysis and modeling tasks,especially with UML,has received little attention.This paper investigates the capabilities of generative AI to aid in the creation of three types of UML models:UML use case models,class diagrams,and sequence diagrams.For this purpose,we designed an AI-aided UML modeling task in our course on software requirements modeling.50 undergraduates who majored in Software Engineering at Wuhan University completed the modeling task and the corresponding online survey.Our findings show that generative AI can help create these three types of UML models,but its performance is limited to identifying essential modeling elements of these UML models.

Robustness of Complex Networks under Attack and Repair

到建筑群的坚韧性在攻击和修理下面联网的学习，我们介绍复杂网络的一个修理模型。基于模型，我们介绍二新数量，即攻击部分 fa 和从来没被攻击过的节点的最大的度一，到学习经分解，批评攻击部分和亲戚在攻击和修理下面复杂网络的巨大的部件缩放，用产生的方法工作。我们显示出经分解并且数字地修理策略显著地提高没有规模的网络的坚韧性和坚韧性改进的效果，这对有一个更小的度代表的没有规模的网络更好。我们与 reparability 在与复杂网络的坚韧性的理解的关系讨论我们的理论的应用程序。

Numerical Study on the Influence of Boss Cap Fins on Efficiency of Controllable-pitch Propeller

数字模拟被调查揭示推进器老板帽子鳍(PBCF ) 怎么操作利用平均 Reynolds 的海军司烧(RANS ) 方法。另外，一个可操纵螺距推进器的开的水效率上的 PBCF 的影响机制的探索通过开的水特征曲线，片表面压力分发和中心被分析优化分发。在这个基础上，包括机翼侧面，直径，安装的轴的位置和可操纵螺距推进器的开的水效率上的环绕的安装角度的参数的影响被调查。数字结果出现：为可操纵螺距推进器，当老板帽子鳍的半径是 1.5 次有在轴的方向的一个最佳的安装位置的推进器中心时，产生的戳在最佳，并且它的最佳的环绕的安装位置是前面的延期线和在鳍根的前面的二条邻近的推进器根的后端的中点。在这些最佳的参数下面，有不同进展速度系数的可操纵螺距推进器的开的水效率的获得比 0.01 大，它近似说明开的水效率的 1%5% 的增加。

A Numerical Method on Inverse Determination of Heat Transfer Coefficient Based on Thermographic Temperature Measurement

处于一个多维的热传导问题的热转移系数基于 thermographic 温度测量从反的热传导问题的答案被获得。与有限体积方法一起，修改一个维的修正方法(MODCM ) 为两 twoand 被采用三维的反的问题。一系列数字实验被进行以便验证方法的有效性。另外，温度测量错误的效果，重复的结束标准，反的问题的结果上的等等被调查。方法是能成功地解决反的热传导问题的简单、稳定、精确的，这被证明。

Numerical Calculation of Supercavitating Flows over the Disk Cavitator of a Subsonic Underwater Projectile

为了在 supercavitating 上处理可压缩的液体的效果，溢出射弹的亚声的磁盘 cavitator，一个有限的卷方法基于理想的可压缩的潜在的理论被提出。由使用连续性方程和 Tait 状态方程以及 Riabouchinsky 闭合模型，一个反的问题答案为 supercavitating 流动被介绍。根据 supercavity 的表面上的刺不进的条件，为 supercavity 形状的一个新反复的方法被设计在 supercavity 形状上处理压缩的可能性的效果，压力拖系数和密度地。由这个方法，低成穴数字能被计算。计算结果与试验性的数据和实验公式同意很好。以亚声的条件，液体压缩的可能性将使 supercavity 成为长度和半径增加。supercavity 扩展，但是留下球状体。supercavity 的第一 1/3 部分上的效果不是明显的。成穴数字或马赫数字增加的射弹增加的 drag 系数。与马赫数字增加，压缩的可能性是越来越重要的。根据 supercavitating 流动的精确计算被担心，压缩的可能性必须被考虑。

Optimal observation configuration of UAVs based on angle and range measurements and cooperative target tracking in three-dimensional space

This article investigates the optimal observation configuration of unmanned aerial vehicles(UAVs) based on angle and range measurements, and generalizes predecessors' researches in two dimensions into three dimensions. The relative geometry of the UAVs-target will significantly affect the state estimation performance of the target, the cost function based on the Fisher information matrix(FIM) is used to derive the FIM determinant of UAVs' observation in three-dimensional space, and the optimal observation geometric configuration that maximizes the determinant of the FIM is obtained. It is shown that the optimal observation configuration of the UAVs-target is usually not unique, and the optimal observation configuration is proved for two UAVs and three UAVs in three-dimension. The long-range over-the-horizon target tracking is simulated and analyzed based on the analysis of optimal observation configuration for two UAVs. The simulation results show that the theoretical analysis and control algorithm can effectively improve the positioning accuracy of the target. It can provide a helpful reference for the design of over-the-horizon target localization based on UAVs.

Effects of deoxidizing degree on the pitting corrosion behavior of carbon and manganese steels

Nine steels with different deoxidizing degrees and two comparative steels were selected. Their pitting initiation susceptibility was compared by means of potentiodynamic polarization tests in 3wt% NaCl solution. The pit propagation rate was evaluated in artificial sea water and 3wt% sea salt solution by simulating occluded corrosion cell （SOCC） test and hanging plate test, respectively. The composition of inclusions and corrosive feature were studied by scanning electron microscopy （SEM）, electron probe micro-analysis （EPMA）, and optical microscopy （OM）. The results indicate that sulfide inclusions in steel are the sites for pit nucleation. The sulphide inclusions vary in shape from short spindle-like to long strip-like with increasing deoxidizing degree. Under the same conditions, the lower the deoxidizing degree gets, the lower the pitting initiation susceptibility becomes, and the stronger the resistance to pit propagation exhibits. For steels with different deoxidizing degrees, their pitting initiation susceptibility is mainly influenced by thermodynamic stability, while the pit propagation rate is primarily subject to the characteristics of inclusions in steel.