• 中国科技核心期刊
  • JST收录期刊

2020 Vol. 28, No. 2

Display Method:
Complex Modal Decomposition and Characteristics Analysis of the Midline Motions of Swimming Fish Propelled by Undulating Body and Caudal Fin
CUI Zuo, JIANG Hong-zhou
2020, 28(2): 119-125. doi: 10.11993/j.issn.2096-3920.2020.02.001
Abstract:
In nature, the majority of fishes obtain their extraordinary swimming abilities of fast speed and high efficiency by propagating their midline motions backward. In this paper, the midline motions and their complex modal characteristics are analyzed by the method of complex orthogonal decomposition(COD). From the perspective of modal analysis, the movement of a swimming fish is in essence the forced vibration of viscoelastic body in fluid environment, and the motions are of complex modal shapes. According to the COD method, the midline motions are decomposed into the travelling and standing components. The correlation coefficient of the real and imaginary parts of complex modal shape is used to define the travelling index. Based on the analysis of the motions of two kinds of anguilliform fish(Pholis Laeta) and subcarangiform fish(Rainbow Trout), the travelling indexes of their midline motions are 0.793 and 0.604, respectively. It is shown that the midline motions of Pholis Laeta contain a large proportion of travelling wave, while the midline motions of Rainbow trout contain a larger proportion of standing wave. These biological results verify the complex modal characteristics of the midline motions, and the complex modal characteristics have close relation to the dynamic properties of fish body and the swimming patterns.
Numerical Simulation and Experiment on Fluid Field Characteristic of Planing for Supercavity Vehicle Tail
ZHANG Ke, SUN Shi-ming, YAN Kai, WANG Zhi, LI Peng
2020, 28(2): 126-130. doi: 10.11993/j.issn.2096-3920.2020.02.002
Abstract:
The planing lift acting on the tail of a supercavitating vehicle has an important influence on its underwater moving posture. In this paper, the volume of fluid (VOF) multiphase flow model was employed to numerically simulate the supercavitating vehicle’s tail planing in cavity at different attack angles. The numerical simulation was verified by comparison with the experimental data. Then, the deformation of the cavity and the variation of the pressure distribution were analyzed. Numerical simulation results showed that the cavity curled towards the vehicle surface near the wetted area with pressure gradient, which produced an upward splashing flow. The decay rate of the pressure along the cavity outline is larger than that along the bottom edge of the vehicle.
RBF Neural Network Integral Sliding Mode Control for Three-Dimensional Path Following of Underactuated AUV
HUO Yu-tong, GUO Chen, YU Hao-miao
2020, 28(2): 131-138. doi: 10.11993/j.issn.2096-3920.2020.02.003
Abstract:
For the three-dimensional path following problem of an underactuated autonomous undersea vehicle(AUV) under the upper bound of unknown parameter perturbation, a spatial path-following controller is proposed based on the radial basis function(RBF) neural network integral sliding mode to reduce chattering caused by external disturbance and sliding mode. The position error stabilization of the path following is converted into the stabilization of the line of sight (LOS) angle error by introducing the Serret-Frenet local frame and the LOS guidance law. And the kinematic “virtual control law” is designed for stabilization of the LOS error based on the Lyapunov direct method. Then, the dynamic path-following controller is developed by introducing the RBF neural network and the integral sliding mode surface. The stability of the designed path-following controller is analyzed by using Lyapunov stability theory. Simulation results show that this path-following controller can effectively follow the three-dimensional straight path, improve the control accuracy, reduce the chattering, and display certain robustness to the external disturbance without losing its rapidity.
Effects of Observation Geometry on Accuracy Distribution Characteristic of TDOA Localization System in Deep Sea
ZHANG Xu, LI Zhi-sheng, QIU Ren-gui, DONG Nan
2020, 28(2): 139-148. doi: 10.11993/j.issn.2096-3920.2020.02.004
Abstract:
To stably localize an acoustic target in a large area of deep sea, the accuracy and coverage characteristic are required to be evaluated under pre-selected observation geometry condition in the measurement system design. Aiming at this problem, a simulation method was presented for analyzing the distributional characteristics of accuracy in underwater acoustic localization with multiple base stations by time difference of arrival(TDOA). The climatological environment in the center of Northern Pacific was selected as background, and the sound field was calculated by BELLHOP Gaussian ray model. Main errors were randomly superimposed by Monte-Carlo method and propagated to finally estimated locations, such that the distribution of root mean square error(RMSE) was established by grid calculation with large samples under typical geometry condition of 4-receiver, 5-receiver or 6-receiver array. The results indicated that the localization performance using direct waves was clearly different from that using first-seabed-reflected waves, and the former was more accurate while the later was better in coverage. For the localization with direct waves, the accuracy was better in the central area of array than that in the marginal one. For the localization with first-seabed-reflected waves, the accuracy became worse in the area several kilometers around the center of array. In another case, the RMSE showed an asymmetric distribution when one corner station was invalid or the central station shifted, the relatively high accuracy area was confined to the active station number, but the full measurement area failed to be covered. Compared with the existing researches, this research provides an applicable way to evaluate and analyze the influence of observation geometry on accuracy distribution and coverage characteristic.
Repetitive Motion Control Algorithm Based on Cosine Feedforward Method and Its Application to Underwater Bionic Propulsion System
ZHAO Xiao-rui, YU Yang, LI Zhen-shan, ZHAO Guo-ping, ZHENG Lin
2020, 28(2): 149-154. doi: 10.11993/j.issn.2096-3920.2020.02.005
Abstract:
The conventional proportional integral derivative(PID) control algorithm will generate amplitude attenuation and phase lag in the periodic sinusoidal motion follow-up, and the larger the load is, the more serious the amplitude attenuation and the phase lag are, which makes the conventional PID control algorithm cannot meet the high-precision follow-up requirement of the bionic propulsion motion. And for a repetitive controller designed for periodic repetitive motion, its compensation output may be delayed for one motion cycle once external disturbance exists, which leads the controller not to be applicable for the underwater variable load operating conditions. The above controllers cannot meet the performance requirements for the underwater bionic propulsion system. Therefore, this paper proposes a cosine feedforward compensation control algorithm based on the feedforward control idea to combine the conventional PID controller for an underwater propulsion system in variable load conditions. A composite feedforward controller is hence constructed to eliminate the amplitude and phase errors of sinusoidal follow-up. Experimental results show that the repetitive motion control algorithm based on cosine feedforward method is more effective than the conventional PID control method, and under variable load conditions it can still achieve accurate follow-up of a given sinusoidal motion command with about 60% reduction in the phase difference compared with the results without compensation.
The SINS/DVL Integrated Navigation Algorithm Based on Observable Degree Feedback
LI Zhi-wei, YUE Wei, GAO Sheng-feng, CAI Peng, ZHU Hai-rong
2020, 28(2): 155-161. doi: 10.11993/j.issn.2096-3920.2020.02.006
Abstract:
Aiming at the problem that some system states in strap-down inertial navigation system(SINS)/Doppler velocity log(DVL) integrated navigation have significant influence on navigation accuracy but have relatively weak observability, a SINS/DVL integrated navigation algorithm based on observable degree feedback is proposed. The algorithm quantitatively analyzes the observability of each state parameter of the system, and constructs an adaptive factor based on observability feedback according to the fact that the observability of the system state parameters depends on maneuver states in order to increase the estimated proportion of state parameters when they have high observable degree, and so as to improve the adaptability and accuracy of the algorithm. The performance of the proposed algorithm is verified through lake trial, and the results show that the accumulated error of this observable degree feedback filtering algorithm is obviously smaller than that of the conventional Kalman filter algorithm, and the autonomous navigation time of the SINS/DVL integrated navigation can be prolonged under the same accuracy requirement.
Detection Method of Magnetic Anomaly Signals Based on AlexNet Transfer Learning
LI Qi-fei, WU Fang, HAN Lei-lei, FAN Zhao-peng, LI Pei-zong
2020, 28(2): 162-167. doi: 10.11993/j.issn.2096-3920.2020.02.007
Abstract:
Aiming at the problem in aviation antisubmarine that the magnetic anomaly signals of underwater targets are difficult to detect under low signal-to-noise ratio(SNR), a detection method of magnetic anomaly signals based on AlexNet transfer learning is proposed. Based on the principle of convolution neural network, a large number of signal sequences are obtained by simulating different situations of underwater targets and different flight routes and speeds of the aeromagnetic platform with Gaussian white noise, so as to simulate the signals measured by the magnetic detection platform. Then, the short-time Fourier transform(STFT) is applied to obtain the time-frequency diagram, and the time-frequency features are transferred and trained by using the AlexNet. Finally, the trained AlexNet deep convolutional neural network is tested by the test set. The results show that the AlexNet model has good generalization ability in the field of magnetic anomaly signal detection. When the SNR is -8 dB and the false alarm rate is 3%, the detection probability of magnetic anomaly signal reaches 93%.
Monopulse Dimension-Reduced Space-Time Adaptive Processing Based on Persymmetric Array
WANG Sha, SHI Bo, HAO Cheng-peng
2020, 28(2): 168-173. doi: 10.11993/j.issn.2096-3920.2020.02.008
Abstract:
Reverberation is one of the main interference in the underwater environment, which seriously affects the detection performance of sonar system. Monopulse space-time adaptive processing(STAP) is more suitable for the underwater acoustic environment and can effectively improve the reverberation suppression capability of the moving sonar. However, there are two limitations of huge computational burden and insufficient secondary data in monopulse STAP in practical applications. In this paper, the persymmetric property of the array is applied to the monopulse joint domain localization(JDL)-STAP algorithm. Simulation results show that this algorithm can reduce the dependence on auxiliary data, improve the estimation accuracy of the reverberation covariance matrix, effectively reduce the calculation amount, improve the suppression performance of reverberation and greatly improve the performance of target azimuth estimation.
Underwater Wireless Sensor Network MAC Protocol Based on Dynamical Change Contention Window
SHI Yue, LI Cheng, HAO Kun
2020, 28(2): 174-181. doi: 10.11993/j.issn.2096-3920.2020.02.009
Abstract:
A dynamical change contention window-media access control(DCCW-MAC) protocol is designed to improve the efficiency of communication between autonomous undersea vehicle(AUV) and sensor nodes. The protocol optimizes the contention window value according to the distance between sensor nodes and AUV, and the sending node with high transmission success rate adjusts the back-off time to transmit data package first, which can efficiently utilize channel resources. Simulation results show that DCCW-MAC protocol is applicable to the communication between AUV and nodes, and compared with the traditional CW-MAC protocol under the same number of nodes and Poisson arrival rate, its maximum throughput increases by 5% and the end-to-end delay is reduced by 15%.
Performance Simulation of Multi-Carrier Frequency-Hopping Underwater Acoustic Communication System Based on DPSK
CHEN Bo-heng, WANG Ming-zhou, YUE Ling, KOU Xiao-ming, ZHANG Wen-bo
2020, 28(2): 182-186. doi: 10.11993/j.issn.2096-3920.2020.02.010
Abstract:
Focusing on the problem that underwater acoustic channel has limited available communication bands and strong multi-path effects, a new underwater acoustic communication scheme is proposed. A multi-carrier underwater acoustic communication system is established by using differential phase shift keying(DPSK) and making use of the high bandwidth utilization ratio of multi-carrier(MC) communication and the anti-multipath capability of frequency hopping(FH) communication. And its principle and implementation process are described in detail. Moreover, the bit error ratio(BER) performances of the system under additive white Gaussian noise channel, Rayleigh fading channel and frequency-selective two-path Rayleigh fading channel are simulated and analyzed, and its reliable anti-noise performance is verified. Compared with FH/MFSK communication system, the proposed MC/FH-DPSK communication system achie- ves almost two times higher bandwidth utilization ratio and the similar performance of anti-multipath in the condition of same frequency hopping clearance and parameter of symbol width.
Numerical Simulation on Submerged Jet Reaction of Molten Aluminum and Water Vapor
XU Sheng, YI Yin, SHI Xiao-feng, ZONG Xiao, HAN Xin-bo
2020, 28(2): 187-193. doi: 10.11993/j.issn.2096-3920.2020.02.011
Abstract:
The submerged jet reaction of molten aluminum and water vapor can be used as a new method of hydrogen generation in hydrogen-oxygen closed cycle power system, and can improve the rate of hydrogen generation and the stability and controllability of hydrogen generator. However, this reaction has the characteristics of high temperature, opacity and complex local flow state, so it is difficult to observe the flow field through conventional methods. In order to explore the flow field characteristics of the reaction, this paper uses the non-premixed combustion model in the software Fluent to conduct a numerical simulation on this reaction. The accuracy of probability density function(PDF) query table is improved by the ideal mixture density calculation method, so that the numerical model can simulate the gas-liquid reaction more accurately, and can obtain the parameter distribution of the reaction jet flow field of molten aluminum and water vapor, the variation law of the temperature distribution of flow field and the water vapor core region under different inlet velocities of water vapor. The results show that the numerical model used in this paper can simulate jet combustion reaction reasonably; The flow field of molten aluminum-water vapor reaction jet is composed of water vapor core region and mixed product region, where the water vapor core region occupies much less space in the jet region than the mixed product region; When the inlet velocity of water vapor increases, the highest temperature and volume of the high temperature region rise, and the length of the water vapor core region increases. This research may provide a reference for further study on submerged jet reaction of molten aluminum and water vapor and the design of hydrogen generator.
Flux Linkage Observation of Hybrid Permanent Magnet Memory Machine Based on Full-Order State Sliding Mode Observer
JIANG Xiao-qi, LIU Wei-ting, WEI Hai-feng, ZHANG Yi
2020, 28(2): 194-201. doi: 10.11993/j.issn.2096-3920.2020.02.012
Abstract:
To improve the accuracy of flux linkage observation in on-line tuning of the hybrid permanent magnet memory machine(HPMMM), a hybrid flux linkage observation method of full-order state sliding mode observer is proposed. This method combines a full-order flux linkage observer with the feedback part of the sliding mode to ensure that the current observation converges to the true value. The HPMMM stator current and rotor flux linkage are observed in real time, and the rotor flux linkage observation is obtained with higher precision. The full-order sliding mode observer is applied to the vector control strategy of HPMMM for optimizing the overall control complexity of the system. Simulation shows that, compared with the traditional permanent magnet synchronous motor(PMSM), HPMMM has a wider speed range, smaller direct-axis and quadrature-axis current fluctuation, and faster speed of convergence to actual flux linkage, indicating that the proposed method can further improve the accuracy of the magnetic field orientation by AC pulse during magnetization and demagnetization of HPMMM and enhance the robustness and stability of the system parameters.
Study on Ballistic Characteristics of the Parallel Supercavitating Projectiles
LIU Fu-qiang, LUO Kai, HUANG Chuang, GU Jian-xiao, DONG Xing-jie, PU Han-ping
2020, 28(2): 202-208. doi: 10.11993/j.issn.2096-3920.2020.02.013
Abstract:
To investigate the effects of the spacing of parallel projectiles on the hydrodynamic properties and ballistic characteristics of the projectiles, a water-entry simulation model of projectiles is established on the bases of the volume of fluid(VOF) multiphase flow model, the multi-reference system, the dynamic grid and the mobile computing domain technology. The water-entry free-deceleration processes of single projectile and parallel projectiles are simulated for different spacing of the projectiles, respectively. The results show that: 1) in parallel launching condition, the projectile is subjected to lateral force, when there is an angle of attack, the cavity has obvious offset and is easier to be punctured by the projectile, and the smaller the parallel spacing, the longer the puncturing distance; 2) the drag coefficient of the parallel projectiles is significantly higher than that of the single projectile, and when the parallel spacing is 75 mm, the drag coef-ficient increases by 34.92%; and 3) the stability of the parallel projectiles is affected by the parallel spacing, and in the case that the parallel spacing is 50 mm, the parallel projectiles overturn with instable trajectories, but this effect gradually weakens as the parallel spacing increases, and the trajectories of the parallel projectiles become stable when the parallel spacing is 100 mm. This research may provide reference for engineering application of parallel supercavitating projectiles.
Improved Thermoplastic Charge Technique of DNAN-Based Explosive for Warhead
HA Hai-rong, WANG Tuan-meng, LU Zhong-bao, LI Qin, JIN Dong
2020, 28(2): 209-213. doi: 10.11993/j.issn.2096-3920.2020.02.014
Abstract:
To solve the problem of insufficient explosive charge shrinkage compensation in the warhead, raise the charge density and charge quantity, and optimize the detonation performance of the explosive, an improved thermoplastic charge technique of DNAN-based aluminized explosive for the warhead was proposed on the basis of the conventional thermoplastic charge technique of DNAN-based explosive. In this improved technique, the measures of ensuring the temperature of thermal insulation device, slowing down the charging speed, reducing the transport of explosives and the temperature gradient, prolonging the heat preservation time and redesigning the charge shrinkage compensation device were taken in order to improve the internal quality of warhead charge, reduce the defects and improve the safety of warhead. Comparative test of the conventional and improved techniques showed that the improved charge density of the warhead increased from 1.70 g/cm3 to 1.78 g/cm3, increasing by 4.71%. Both the charge quantity and the internal quality of charge were improved, which made up for the charge defects and restrained the generation of shrinkage cavities and voids. This improved thermoplastic charge technique is simple, practical and reliable.
Conformational Analysis of a New Type of Closed Aluminum Powder Combustion Stirling Underwater Power System
JIN Xu-dong, LÜ Tian, LAN Jian
2020, 28(2): 214-219. doi: 10.11993/j.issn.2096-3920.2020.02.015
Abstract:
To increase the energy density of conventional underwater power systems, a new type of high energy density Stirling underwater power system based on aluminum powder combustion was proposed. An aluminum-water combustion plus hydrogen combustion Stirling underwater power system and an aluminum-water combustion plus hydrogen-oxygen combustion combined with liquid sodium Stirling underwater power system were built by numerical simulation. The energy density and fuel cost of the two new systems were compared with those of conventional diesel-liquid oxygen Stirling power system. Numerical simulation results show that the energy density of the aluminum-water combustion plus hydrogen combustion Stirling underwater power system is 648 Wh/L, which is two times that of the conventional diesel-liquid oxygen Stirling underwater power system, and the fuel cost of the former system is also two times that of the latter one; the energy density of the aluminum-water combustion plus hydrogen-oxygen combustion combined with liquid sodium Stirling underwater power system is 1.7 times that of the conventional diesel-liquid oxygen Stirling underwater power system. As a result, the new type of closed aluminum powder combustion Stirling underwater power system has good application potential in the future underwater power system.
Design Ideas of Unmanned Underwater Launch Test Facility
SONG Jie
2020, 28(2): 220-224. doi: 10.11993/j.issn.2096-3920.2020.02.016
Abstract:
To assess underwater launching technology and avoid test risk of underwater launching vehicle effectively, three design ideas of unmanned underwater launch test facilities of anchoring type, pile leg self-lifting type and caisson type are put forward according to the task requirements with reference to the corresponding foreign design ideas. The composition and function, working principle, working process of the system are briefly described. Based on the real marine environment conditions, the three schemes simulate the launch conditions of the real underwater launch platform realistically, adopt the unmanned mode to ensure their safety, and increase the feasibility of the test facility design schemes with reference to the mature technologies about the designs of such as ships, submarines and offshore platforms. The three schemes are compared in terms of technical difficulties, organization and implementation, and fidelity. The analysis results show that from the aspects of marine environment elements, organization and implementation, maintenance and technical implementation difficulty, all three schemes can meet the underwater launch and test needs of the vehicle, among which the anchored launch platform scheme has the most advantages.
Combined Test Verification and Evaluation Method for Weapons Equipment System
LI Jie, ZHU Yong
2020, 28(2): 225-230. doi: 10.11993/j.issn.2096-3920.2020.02.017
Abstract:
Aiming at the problem that complete system test is difficult to conduct and simulation deduction has some deviation in the test verification of weapons equipment system, a combined verification method for system test is proposed. The system test is decomposed into several series of test stages or links, which can be carried out in different test range or via simulation. It is deduced that the key factor for verification equivalence of the combined test is the Markov property in the test stage or link. The principal formulas of Markov property in the test stage or link are summarized and put forward, and the methods for dealing with special cases are given. Consequently, an evaluation method suitable for combined test verification of weapons equipment system is established. This method may facilitate the test verification and evaluation of weapons equipment system.
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