水下无人系统学报

Influence of Bafflers on Savonius Impeller of Ocean Current Generator

SONG Bao-wei, YANG Chun, TIAN Wen-long

2013, 21(1): 001-5. doi: 10.11993/j.issn.1673-1948.2013.01.001

[Abstract](984) [PDF 433KB](537)

Abstract:
Savonius impeller is widely used in ocean current generator, which has the advantages of low cost and good starting characteristics but lower efficiency. In this study, a novel vertical axis turbine (VAT) is designed by adding three bafflers to a Savoinius blade to improve its power generation efficiency. The output characteristics of the VAT at different rotary speed are analyzed with commercial computational fluid dynamics (CFD) software FLUENT to under-stand the influence of the bafflers on the power generation performance of the turbine impeller. The two-dimensional unsteady flow of the impeller is computed by using sliding mesh, and the basic features of speed field, pressure field, etc. of the impeller under working condition are analyzed. The results show that the maximum averaged power generation coefficient of the propeller reaches 0.481 when the tip speed ratio λ=0.9, which is 10% to 20% higher than that of the Savonius impeller.

A Bayesian Reliability Assessment Method for Torpedo Based on Fuzzy Theory

MENG Fan-liang, ZHOU Xun-chang, LIU Tian-hua, LIU Hong

2013, 21(1): 006-9. doi: 10.11993/j.issn.1673-1948.2013.01.002

[Abstract](857) [PDF 191KB](452)

Abstract:
Conventional Boolean algebra-based reliability assessment methods for a torpedo consider little transition state between ‘qualified’ and ‘unqualified’. In order to assess the reliability level of a torpedo more objectively and ex-actly, a novel reliability assessment model is put forward on the basis of fuzzy mathematics, in which test results are represented by fuzzy numbers. Then the Bayes method is adopted in assessment of reliability level to obtain a fuzzy zone indicating reliability level of a torpedo. This method is more practical and shows a saving in test samples. Feasibility of the present method is verified by an example.

A New Torpedo Weighing Equipment and Measurement Method

ZHANG Tian-mi, ZHU Li-qing

2013, 21(1): 010-14. doi: 10.11993/j.issn.1673-1948.2013.01.003

[Abstract](812) [PDF 340KB](631)

Abstract:
In order to improve the measurement deficiency of existing weighing equipment and increase its measurement precision of weighing parameters such as barycentre and buoyancy center, this paper presents a new type of weighing equipment and its measurement method for various weighing parameters, analyzes and obtains the influence of the sys-tem error on the measurement errors of various weighing parameters. This equipment can improve the deficiency, pro-vide convenient measurement for various weighing parameters in torpedo development and production, and significantly increase the measurement precision. In addition, the proposed measurement method is also applicable to other objects with irregular shape.

Modeling and Simulation of Target Tracking for Underwater Acoustic Homing Weapon

YANG Xiang-feng, YANG Yun-chuan, CHEN Ya-lin

2013, 21(1): 015-19. doi: 10.11993/j.issn.1673-1948.2013.01.004

[Abstract](1484) [PDF 222KB](554)

Abstract:
Target tracking is one of the important directions in the development of modern intellectualized underwater acoustic homing weapon. However, the observation-base is moving and the observation is time-varying when an active acous-tic homing weapon tracks a target. In this study, the parameters of location and attitude from the acoustic homing weapon′s navigation system and the target information detected by the acoustic homing weapon are used to resolve the problem of ob-servation-base movement and time-varying observation. The target coordinates in acoustic homing weapon coordinate systems are transformed to terrestrial coordinate system to resolve the problem of observation-base′s movement, and the sampling time is calculated in real time to resolve the problem of observation′s time-varying. A target tracking model of acoustic homing weapon based on Kalman filter is established. The choosing of filter′s initialization values is analyzed, and the application method of choosing filter initialization values is presented. Simulation results show that the model is accurate, and the tracking algorithm is of faster convergence and better tracking effect.

An Improved Algorithm of Real-time Wavelet Denoising for Target Signal of Torpedo Electromagnetic Fuze

TAN Si-wei, REN Zhi-liang, SUN Chang-cun

2013, 21(1): 020-24. doi: 10.11993/j.issn.1673-1948.2013.01.005

[Abstract](1112) [PDF 268KB](526)

Abstract:
The wavelet transform based on Mallat algorithm cannot process flowing data, it is therefore unable to meet the requirement for real-time denoising of continuous sampling signals. As a result, this paper proposes a novel wavelet transform based on Mallat algorithm modification, called bricklaying algorithm. The ability of the proposed algorithm to process flowing data is analyzed, and the relationship between data flowing and level of wavelet decomposition is de-duced. The bricklaying algorithm is applied to real-time denoising of torpedo electromagnetic fuze signal in the back-ground of additive white Gaussian noise, where a biorthogonal spline wavelet is taken as the wavelet function, and 2-level wavelet decomposition and reconstruction are performed. The feasibility of the bricklaying algorithm in real-time denoising of continuous sampling signals is verified via MATLAB simulations. The results show that the de-noised target signal gains the feature of smooth waveform with smaller distortion.

Optimum Linear Fusion for DOA Estimation with Vector Hydrophone Array

WANG Xu-hu, CHEN Jian-feng, AN Qin-li

2013, 21(1): 025-29. doi: 10.11993/j.issn.1673-1948.2013.01.006

[Abstract](1168) [PDF 231KB](563)

Abstract:
To improve the direction of arrival (DOA) estimation performance of a vector hydrophone array, the estima-tion of signal parameters via rotational invariance technique (ESPRIT) of a vector hydrophone array is studied. Based on analysis of vector array ESPRIT, theoretical estimation covariance formulas of vector array ESPRIT method are deduced, which bring about large estimation covariance at certain target bearing. Consequently, an algorithm of optimum linear data fusion for independent DOA estimation is proposed. Simulation results show that the proposed fusion method im-proves the accuracy of DOA estimation via vector hydrophone array with smaller fluctuation of the estimation covari-ance following target bearing.

A Feature Recognition Method of Target Signal for Torpedo Electromanetic Fuze Based on Wavelet Transform Singularity Detection

CHEN Guang, YU Jin-fang, YANG Qing-hua

2013, 21(1): 030-33. doi: 10.11993/j.issn.1673-1948.2013.01.007

[Abstract](1092) [PDF 243KB](559)

Abstract:
The features of target signal for torpedo electromagnetic fuze must be extracted and recognized exactly to ensure reliable action of torpedo fuze. Lipchitz exponent method for symbolizing signal′s singularity is described, the principle of detecting signal′s singularity based on wavelet transform is introduced, and the presence of singular value in the envelope of the target signal for torpedo electromagnetic fuze after amplitude recognition is analyzed. Then a new recognition method is put forward for the features of time-varying rate and lasting time of the envelope．The method can detect accurately the singular point of the envelope signal by extracting the real feature of target signal and selecting suitable wavelet base function and decomposition scale. Simulation results show that in contrast to traditional recogni-tion methods with analogy circuits, the proposed method is easier in realization with weaker limitation of threshold voltage variation, besides, it has a high recognition precision and good engineering application．

An Optical Transmission Technique for Fiber Wire-guided Torpedo

LIU Xue-chen, HU Peng, ZHAO Yan

2013, 21(1): 034-38. doi: 10.11993/j.issn.1673-1948.2013.01.008

[Abstract](1104) [PDF 213KB](762)

Abstract:
Bidirectional transmission of optical information with high-speed and long-distance in a rapidly laid sin-gle-core guidance optical-cable is a key factor for improving fiber wire-guidance transmission speed, extending trans-mission distance and enhancing information transmission reliability. Considering the characteristics of the torpedo′s fiber wire-guided system, this paper analyzes the techniques about the guidance optical-cable with low dynamic loss, the fiber communication mode selection, the optical signal transmission and receiving, and so on. As a result, an optimum mode of optical transmission for torpedo′s fiber wire-guided system is proposed. This study may provide a reference for improving torpedo′s optical-cable communication capacity.

Design of Guidance Law for Anti-torpedo Torpedo Based on Variable Structure Control

LIU Yang, LI Zong-Ji, ZHANG Xi-Yong

2013, 21(1): 039-42. doi: 10.11993/j.issn.1673-1948.2013.01.009

[Abstract](1351) [PDF 196KB](548)

Abstract:
Aiming at the low hitting precision and big normal overload of traditional torpedo guidance law, a guidance law for an anti-torpedo torpedo(ATT) based on variable structure control is designed. This ATT guidance law is on the basis of a mathematical model of movement relation between an ATT and a target torpedo. A variable structure control model is established taking course angle as control parameter and angular speed of line-of-sight as sliding mode surface. The proposed model needs a few parameters, and the parameters can be self-adaptively adjusted. Theoretical analysis and simulation show that the ATT guidance law is very robust for model parameters and environmental interference, and can gain high hitting precision and stable trajectory.

Numerical Simulation of Supersonic Flow Field in Rotor Blade Cascade for Impulse Torpedo Turbine

GUO Zhao-yuan, CAO Hao, ZHAO Wei-bing

2013, 21(1): 043-47. doi: 10.11993/j.issn.1673-1948.2013.01.010

[Abstract](1230) [PDF 332KB](667)

Abstract:
To study fluid characteristic in torpedo turbine flow passages and guide structure design of the flow pas-sages, the flow field in rotor blade cascade of an impulse supersonic torpedo turbine was numerically investigated by computational fluid dynamics (CFD) method. The detail information of flow, total pressure loss, and aerodynamic load and temperature load on a blade were analyzed. Simulation results show that: flow in rotor flow passages is very com-plicated; blade incidence angle exerts significant effect on the flow; the larger the incidence angle, the more severe the boundary layer separation, the stronger the shock wave, and the more the total pressure loss; when a blade is pass through the nozzle area, the aerodynamic load on it first increases and then decreases; heavier aerodynamic load leads to smaller temperature load and temperature gradient in the blade.

Analysis of Plastic Deformation Characteristics for High-speed Impeller

GAO Xing, HUANG Ke, DUAN Hao

2013, 21(1): 048-53. doi: 10.11993/j.issn.1673-1948.2013.01.011

[Abstract](883) [PDF 332KB](570)

Abstract:
This paper establishes a physical model of a high-speed impeller for excessive speed test with reasonable abstraction and simplification to quantitatively analyze the plastic deformation range of the impeller. As a result, the analytical solutions of the stress and deformation at given rotary speed as well as the elastic and plastic deformation areas are obtained. Comparison between the stresses from the excessive speed tests and from the calculation shows an error of 6%, demonstrating the present method can be used for quantitatively analyzing the deformation of various im-pellers at different rotary speeds to provide a reference for impeller design.

Key Process Control for Range Test

CHEN Dong-ke, ZHANG Di

2013, 21(1): 054-57. doi: 10.11993/j.issn.1673-1948.2013.01.012

[Abstract](1347) [PDF 140KB](569)

Abstract:
Quality control of key process is important and difficult in the quality management system GJB9001B. Ac-cording to the problems in the key process of range test found in system internal audit and considering the actual situa-tion of range test, a practical method for interpreting key process definition and identification is proposed in this paper. Taking an acceptance trial for example, this study presents the operations for the key process, such as the identification, the list preparation and evaluation, and the control, in order to provide a reference for the quality control of range test.

Identification Method of Torpedo-Target Hydroacoustic Signal in Torpedo Sea Trial

SUN Tao, HOU Dai-wen

2013, 21(1): 058-61. doi: 10.11993/j.issn.1673-1948.2013.01.013

[Abstract](1252) [PDF 284KB](563)

Abstract:
In order to efficiently understand torpedo working condition under water in torpedo trials, a third-party monitoring system is usually used to simultaneously record both signals of torpedo and target for subsequent analysis. In this study, sea trial scenario is analyzed, and a fast Fourier transform-based both signals identification method is pro-posed by combining time domain with frequency domain for torpedo-target monitoring system. Identification results of the monitoring system in a sea trial verify the validity of the proposed method.

Efficacy Function Method for Comprehensive Performance Assessment of Torpedo

ZHAO Wei, TIAN Zheng, YANG Li-juan, WEI Jian-long, YU Wei, LI Jie

2013, 21(1): 062-67. doi: 10.11993/j.issn.1673-1948.2013.01.014

[Abstract](1427) [PDF 250KB](603)

Abstract:
To assess systematically the performance of a torpedo, one ought to check each item in its acceptance test and obtain the comprehensive index representing torpedo overall performance. A new efficacy function method is proposed for the comprehensive performance assessment in torpedo sea trial. The method first nondimensionalizes relatively the measured value of each item, and then nondimensionalizes absolutely the value by adjusting its weight. After weighted synthesis, quantitative assessment is gained by the efficacy function method. The effectiveness of the proposed method is verified through an example.

A Fast Fitting Model of Submarine Target Strength Forecast Result for Torpedo Guidance System

WANG Xin-ning, SUN Shu

2013, 21(1): 068-70. doi: 10.11993/j.issn.1673-1948.2013.01.015

[Abstract](1187) [PDF 212KB](542)

Abstract:
Mathematical model for torpedo guidance computation ought to be fast and accurate due to the limited hardware of guidance system and the fast attack process. Based on block element method, the target strengths of a submarine in dif-ferent frequencies and azimuths are forecast precisely in this paper. Firstly, the curves of azimuth angle and target strength in single frequency are fitted by using the least squares method. Then, Lagrangian interpolation is applied to the curves taking frequency as the variable to obtain a fast fitting model of submarine target strength forecast result with variables of frequency and horizontal azimuth, which can meet the real-time computation for torpedo guidance system. Simulation re-sults show that this method has higher computation speed and precision than existing equivalent scattering area formula and ellipsoid correction model.

Effects of Evidences on Type Identification of Sub-launched Torpedo

CHEN Yan-hui, HONG Hao

2013, 21(1): 071-75. doi: 10.11993/j.issn.1673-1948.2013.01.016

[Abstract](1283) [PDF 130KB](618)

Abstract:
Guidance type identification of an incoming torpedo is a premise of defending surface ship against torpedo exactly. Extracting and analyzing evidences are essential for establishing the identification system of torpedo types. In this study, four evidences are extracted from incoming torpedo information on the basis of tactical and technological characteristic information; three evidences are extracted from battlefield surrounding, and six evidences are extracted from naval battle state. The affecting mechanism of these evidences on type identification of torpedo guidance is ana-lyzed in detail, and a method of evidences fusion is discussed. This study may provide a theoretical support for objec-tively describing the basic probability assignment of evidences, and facilitate practical application of the type identifica-tion system of sub-launched torpedo.

An Identification Method of Ship Classification Based on Wavelet Frequency Band Statistical Features

PAN Lin, ZHANG Xiao-min, LIU Yi-hai

2013, 21(1): 076-80. doi: 10.11993/j.issn.1673-1948.2013.01.017

[Abstract](1070) [PDF 226KB](474)

Abstract:
This paper proposes an identification method of ship classification based on wavelet frequency band statisti-cal features to improve effectively the detection probability of a ship. In this method, the maximum of wavelet modulus for in-band signal of ship-radiated noise and the frequency band energy of outer band signal are extracted, respectively, by using wavelet transform, and the combination of the two target features is used for identifying a ship target. This method is verified by 58 sets of measured data of radiated noise from sea trial, and the results show an improved detec-tion probability of 97%.

2013 Vol. 21, No. 1

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