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Pressure and velocity cross-spectrum of normal modes in low-frequency acoustic vector field of shallow water and its application

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Journal of Systems Engineering and Electronics 2015年第2期26卷 241-249页

作者： Yun Yu Qing Ling Jiang Xu Naval academy of armament

The pressure and horizontal particle velocity combined descriptions in the very low frequency acoustic field of shallow wa- ter integrated with the concept of effective depth of Pekeris wave- guide is proposed, especially the active component of the pressure and horizontal particle velocity cross-spectrum, also called ho- rizontal complex cross acoustic intensity, when only two normal modes are trapped in the waveguide. Both the approximate theo- retic analysis and the numerical results show that the sign of the horizontal complex cross acoustic intensity active component is independent of the range when vertically deployed receiving dual sensors are placed in appropriate depths, the sum of which is equal to the waveguide effective depth, so it can be used to tell whether the sound source is near the surface or underwater; while the range rate is expected to be measured by utilizing the sign distribution characteristic of the reactive component. The further robustness analysis of the depth classification algorithm shows that the existence of shear waves in semi infinite basement and the change of acoustic velocity profiles have few effects on the application of this method, and the seabed attenuation will limit the detection range, but the algorithm still has a good robustness in the valid detection range.

关键词： low frequency acoustic vector field effective depth complex cross acoustic intensity active component target depth classificatio

Fractionally Spaced Equalization Algorithms in 60GHz Communication System

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China Communications 2014年第6期11卷 23-31页

作者： YUE Guangrong DONG Aixian HONG Hao GUO Jianmei WANG Lei National Key Laboratory of Science and Technology on Communications University of Electronic Science and Technology of China The navy academy of armament

Several fractionally spaced equalizers(FSE) which could be used in 60 GHz systems are presented in this paper. For 60 GHz systems, low-power equalization algorithms are favorable. We focus on FSE in both time domain(TD) and frequency domain(FD) in order to meet different complexity requirements of 60 GHz systems. Compared with symbol spaced equalizer(SSE), FSE can relax the requirement of sampling synchronization hardware significantly. Extensive simulation results show that our equalization algorithms not only eliminate ISI efficiently, but are also robust to timing synchronization errors.

关键词： fractionally spaced equalizers 60GHz timing synchronization lowcomplexity

Dynamic analysis of a guided projectile during engraving process

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Defence Technology（防务技术） 2014年第2期10卷 111-118页

作者： Tao XUE Xiao-bing ZHANG Dong-hua CUI School of Energy and Power Engineering Nanjing University of Science and Technology navy academy of armament

The reliability of the electronic components inside a guided projectile is highly affected by the launch dynamics of guided *** engraving process plays a crucial role on determining the ballistic performance and projectile *** paper analyzes the dynamic response of a guided projectile during the engraving *** considering the projectile center of gravity moving during the engraving process,a dynamics model is established with the coupling of interior ballistic *** results detail the stress situation of a guided projectile band during its engraving ***,the axial dynamic response of projectile in the several milliseconds following the engraving process is also *** further explore how the different performance of the engraving band can affect the dynamics of guided projectile,this paper focuses on these two aspects:(a) the effects caused by the different band geometry;and(b) the effects caused by different band *** time domain and frequency domain responses show that the dynamics of the projectile are quite sensitive to the engraving band width.A material with a small modulus of elasticity is more stable than one with a high modulus of elasticity.

关键词：雕刻工艺制导炮弹发射动力学防弹性能动力学模型内弹道方程电子组件动态响应

Influence of Unidirectional Tensile External-loading on Electromagnetic Property of the Perforated Frequency Selective Surface Illuminated by Electromagnetic Wave Incident at Arbitrary Angles

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Journal of Shanghai Jiaotong university(Science) 2010年第1期15卷 94-102页

作者：张立军王德禹朱锡张凌江 State Key Laboratory of Ocean Engineering Shanghai Jiaotong University Department of Ship and Ocean Engineering Navy University of Engineering Naval academy of armament

That whether unidirectional tension changes the influence of incident angle on FSS's(frequency selective surface) electromagnetic(EM) property and whether incident angle changes the effect of unidirectional intension on FSS's EM property is *** pattern and magnitude of these changes are ***,the analyses for the mechanism of unidirectional tension's influence and the mechanism of the coupling between the influences of unidirectional tension and incident angle are ***,according to the mechanism of these influences,Mechanics-Electromagnetics co-analysis is conducted based on mechanics finite element method and electromagnetics finite element *** frequency responses of the FSS which is under different unidirectional tensions and illuminated by EM wave incident at different angles are *** concept"unidirectional tensile sensitivity of FSS"is put forward along with two unidirectional tensile sensitivity *** using angular sensitivity-factor and unidirectional tensile sensitivity-factor,the influences of unidirectional tension and incident angle,which are coupled with each other,are expatiated *** results show that these influences have two ***,basing on Mode Matching Method and according to the results of numerical investigation,one principle for the layout of FSS with apertures is *** suggestions for further research are given.

关键词： frequency selective surface (FSS) radar absorbing structure unidirectional tensile sensitivity angular sensitivity mechanics-electromagnetics co-analysis composite ship integrated mast

Neural Network Prediction Model for Ship Hydraulic Pressure Signal Under Wind Wave Background

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Journal of Shanghai Jiaotong university(Science) 2015年第2期20卷 224-227页

作者：李松张春华石敏 Naval academy of armament Unit 61741

The ship hydraulic pressure signal is one of the important characters for the target detection and recognition. At present, most of the researches on the detection focus on the ways in the time domain. The ways are usually invalid in the large wind wave background. In order to solve the problem efficiently, we present an effectual way to detect the ship using the ship hydraulic pressure signal. Firstly, the signature in the proposed method is decomposed by wavelet-transform technique and reconstructed at the low-frequency region. Then,a predictive model is set up by using the radial basis function(RBF) neural network. Finally, the signature predictive error is regarded as the testing signal which can be used to judge whether the target exists or does *** practical result shows that the method can improve the signal to noise ratio(SNR) obviously.

关键词： hydrodynamic pressure signal wavelet-transform radial basis function(RBF) neural network signal to noise ratio(SNR) predictive e

The design of propeller and propeller boss cap fins(PBCF) by an integrative method

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Journal of Hydrodynamics 2014年第4期26卷 586-593页

作者：马骋蔡昊鹏钱正芳陈科 Institute of Naval academy of armament Department of Ship Engineering Naval University of Engineering

Generally, after a marine propeller design, the propeller boss cap fins （PBCF） design concerns with an optimal selection of model test results, without a due consideration of the interaction between the PBCF and the propeller. In this paper, the PBCF and the propeller are considered as a whole system with their design as an integrative process, in which the concept of the increased loading in the blade root is incorporated. The load distribution on the blade becomes well-proportioned due to the increased loading in the blade root, and it is advantageous to the reduction of the vibratory force and the blade tip vortex. The blade root area is stronger in withstanding forces, and is not easy to be vibrated, therefore, the increased loading there is beneficial to the noise reduction. The disadvantage of the increased loading in the blade root is the generation of the hub vortex behind the boss cap, but the hub vortex can be broken up by the energy saving hydrodynamic mechanism of the PBCF. The integrative design method introduced in this paper can provide a higher efficiency for propellers under the same design conditions. In this paper, an integrative propeller and PBCF design method including the theoretical design and the numerical optimization design is proposed, based on the potential flow theory, the CFD tools, the improved particle swarm optimization algorithm, and the model tests. A propeller with the PBCF is designed based on the method of integrated increased loading in the blade root for a cargo vessel in this paper. The cavitation tunnel model test results show that the propeller and the PBCF thus designed enjoys a higher efficiency, and the design method is effective, reliable and practical.

关键词： propeller boss cap fins (PBCF) integrative design increased loading in blade root

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Applied Mathematics and Mechanics(English Edition) 2011年第12期32卷 1491-1504页

作者：张振华汪玉张立军袁建红赵海峰 Department of Ship and Ocean Engineering Naval University of Engineering Naval academy of armament

The final anomalous sag distortion of the ship girder subjected to the near field underwater explosion （undex） below the middle ship is studied. The sinking exercise of Spruance class destroyer DD973 sunk by one MK48 torpedo is first presented, and a simulation model is established. The exponential attenuation phase, the reciprocal attenuation phase, the post reciprocal attenuation phase, and the negative pressure phase of the undex load are precisely applied in this model. The fluid-solid interaction, the added water mass, the gravity, and the change of buoyancy are also taken into account. The similarity theory is then used to analyze the dynamic response of the ship girder. Similarity parameters and theory prediction formulae of the dynamic response of the ship girder are presented, The physical meaning and influences of these similarity parameters are analyzed.

关键词： underwater explosion (undex) ship girder near field anomalous response,similarity analysis

Thermal insulation and cooling properties of thermal barrier coatings of flame baffles

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Journal of Beijing Institute of Technology 2011年第4期20卷 558-563页

作者：许卫宝刘保果宋遒志 School of Shipbuilding Engineering Harbin Engineering University navy armament Department School of MechatronicalEngineering Beijing Institute of Technology

In order to study the thermal insulation and cooling properties of thermal barrier coatings of a flame baffle,several ZrO2 thermal barrier coatings with different thicknesses were prepared on the surface of aluminium-alloy flame-baffle samples by plasma *** relations between temperature and time of these samples were tested when they were heated by combustion *** relations between temperature of the coatings and the sample bodies and time were also tested when the samples at high temperatures were cooled by *** experimental results indicated that ① the thicker the thermal barrier coatings,the better the thermal insulation effect of the thermal barrier;② the higher the temperature,the more significant of the thermal insulation of the thermal ***,in the case of water-cooling,the cooling rate of the coatings was greatly subject to the plate body and the cooling rate of coatings below 1.0mm was equivalent to that of the plate body.

关键词： flame baffle thermal barrier coating cooling factors

Detecting Stationarity and Nonlinearity in Propeller Singing Signal

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Journal of Shanghai Jiaotong university(Science) 2010年第4期15卷 447-450页

作者：于大鹏赵德有汪玉 Department of Naval Architecture Dalian University of Technology Naval academy of armament

The propeller singing is such a complex fluid-structure coupling phenomenon that needs to study intensively. In this paper, the stationarity of propeller singing signal is tested by the recurrence plot technique. According to surrogate data, the singing time series has nonlinearity character. And the nonlinearity of time series is not caused by the static nonlinear measurement function but the intrinsic character itself based on further research. The results provide an objective basis for analyzing the propeller singing signal with the nonlinear time series technique

关键词： propeller singing signal stationarity test nonlinearity test surrogate data