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

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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Improved Dynamic Bayesian Networks in Sea-battlefield Situation Assessment

Improved Dynamic Bayesian Networks in Sea-battlefield Situat...

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The 2012 International Conference on Advanced Material and Manufacturing Science(ICAMMS 2012)

作者： Yongtao Yu Ying Ding institute of stratege and policy naval avademy of armament Beijing Sino-Ocean JIYE Propetry Management CO. LTD

How to efficiently evaluate the dynamic and complex the sea-battlefield situation facing the reality of the problem is the operational decision supportAccording to research sea-battlefield situation assessment based on improved dynamic Bayesian networksFirst constructed the sea-battlefield situation assessment Bayesian networks model;second specific assessment task to establish the corresponding dynamic Bayesian networks;again reintroduced extended hidden variables,supplemental situation information to construct improved dynamic Bayesian networks;finally,according to the battlefield event reasoning,complete sea-battlefield situation assessment

关键词： Dynamic Bayesian Sea-battlefield situation assessment

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Cooperative multi-target hunting by unmanned surface vehicles based on multi-agent reinforcement learning

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Defence Technology（防务技术） 2023年第11期29卷 80-94页

作者： Jiawei Xia Yasong Luo Zhikun Liu Yalun Zhang Haoran Shi Zhong Liu College of Weaponry Engineering Naval University of EngineeringWuhan430033China institute of Vibration and Noise Naval University of EngineeringWuhan430033China

To solve the problem of multi-target hunting by an unmanned surface vehicle(USV)fleet,a hunting algorithm based on multi-agent reinforcement learning is ***,the hunting environment and kinematic model without boundary constraints are built,and the criteria for successful target capture are ***,the cooperative hunting problem of a USV fleet is modeled as a decentralized partially observable Markov decision process(Dec-POMDP),and a distributed partially observable multitarget hunting Proximal policy Optimization(DPOMH-PPO)algorithm applicable to USVs is *** addition,an observation model,a reward function and the action space applicable to multi-target hunting tasks are *** deal with the dynamic change of observational feature dimension input by partially observable systems,a feature embedding block is *** combining the two feature compression methods of column-wise max pooling(CMP)and column-wise average-pooling(CAP),observational feature encoding is ***,the centralized training and decentralized execution framework is adopted to complete the training of hunting *** USV in the fleet shares the same policy and perform actions *** experiments have verified the effectiveness of the DPOMH-PPO algorithm in the test scenarios with different numbers of ***,the advantages of the proposed model are comprehensively analyzed from the aspects of algorithm performance,migration effect in task scenarios and self-organization capability after being damaged,the potential deployment and application of DPOMH-PPO in the real environment is verified.

关键词： Unmanned surface vehicles Multi-agent deep reinforcement learning Cooperative hunting Feature embedding Proximal policy optimization

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Time-Series Forecasting Using Autoregression Enhanced k-Nearest Neighbors Method

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Journal of Shanghai Jiaotong university(Science) 2013年第4期18卷 434-442页

作者：潘峰赵海波刘华山 School of Information Science and Technology Donghua University institute of Aircraft Equipment Naval Academy of Armament

This study proposes two metrics using the nearest neighbors method to improve the accuracy of time-series forecasting. These two metrics can be treated as a hybrid forecasting approach to combine linear and non-linear forecasting techniques. One metric redefines the distance in k-nearest neighbors based on the coefficients of autoregression (AR) in time series. Meanwhile, an improvement to Kulesh's adaptive metrics in the nearest neighbors is also presented. To evaluate the performance of the two proposed metrics, three types of time-series data, namely deterministic synthetic data, chaotic time-series data and real time-series data, are predicted. Experimental results show the superiority of the proposed AR-enhanced k-nearest neighbors methods to the traditional k-nearest neighbors metric and Kulesh's adaptive metrics.

关键词：计算机模式识别图像处理应用程序

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Bayesian Reliability Assessment and Degradation Modeling with Calibrations and Random Failure Threshold

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Journal of Shanghai Jiaotong university(Science) 2016年第4期21卷 478-483页

作者：黄金波孔德景崔利荣 School of Management and Economics Beijing Institute of Technology Beijing 100081 China naval Academy of armament Beijing 100161 China

A degradation model with a random failure threshold is presented for the assessment of reliability by the Bayesian approach. This model is different from others in that the degradation process is proceeding under pre-specified periodical calibrations. And here a random threshold distribution instead of a constant threshold which is difficult to determine in practice is used. The system reliability is defined as the probability that the degradation signals do not exceed the random threshold. Based on the posterior distribution estimates of degradation performance, two models for Bayesian reliability assessments are presented in terms of the degradation performance and the distribution of random failure threshold. The methods proposed in this paper are very useful and practical for multi-stage system with uncertain failure threshold. This study perfects the degradation modeling approaches and plays an important role in the remaining useful life estimation and maintenance decision making.

关键词：可靠性评估模型贝叶斯方法失效阈值退化模型校准程序建模方法随机降解过程

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ANALYTICAL AND NUMERICAL INVESTIGATIONS OF TWO SPECIAL CLASSES OF GENERALIZED CONTINUUM MEDIA

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Acta Mechanica Solida Sinica 2011年第4期24卷 326-339页

作者： Zhaohui Zhang Zhanli Liu Yuan Gao Junfang Nie Zhuo Zhuang Department of Engineering Mechanics School of AerospaceTsinghua UniversityBeijing 100084China institute of Nuclear and New Energy Technology Tsinghua UniversityBeijing 100084China naval Academy of armament Beijing 100073China

In this paper,the micromorphic theory and the second gradient theory are proposedwhere the micromorphic model can be reduced to the second gradient model with the vanishing relative deformation between macrodeformation gradient and *** solutions for the simple shear problem in the case of a general small strain isotropic elasticity micromorphic model and the second gradient model are presented,***,uniaxial tension of a constrained layer with two different boundary conditions is also analytically ***,the micromorphic theory is implemented numerically within a two-dimensional plane strain finite element framework by developing two isoparametric elements.

关键词： micromorphic second gradient boundary layer size effect finite element

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Surface plasmon resonance sensor based on molecularly imprinted films for the detection of pentaerythritol tetranitrate （PETN）

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Journal of Beijing institute of Technology 2014年第1期23卷 126-130页

作者： ZHANG Qing-wen BAO Han ZHAO Feng-qin BAO Si-miao WEI Tian-xin ZHANG Peng CUI He Key Laboratory of Cluster Science of Ministry of Education Beijing Institute of Technology Beijing 100081 China China naval Academy of armament Beijing 100073 China China Ship Research Development Academy Beijing 100085 China

A novel surface plasmon resonance （SPR） sensor based on molecularly imprinted films （MIFs） was developed for the detection of pentaerythritol tetranitrate （PETN）. In this work, the thin MIFs were formed on a gold sensor chip through thermal co-polymerization of functional mono- mers （methacrylic acid, MAA） and crosslinking monomers （ethylene glycol dimethacrylate, EGD- MA） in the presence of template molecules PETN. The template molecules PETN were subsequently removed from the MIFs simply by rinsing the MIFs with a mixture of acetonitrile and acetic acid 9：1 （ v/v）, thus the recognition sites were formed for specific detection of PETN. According to the mass coverage equation, the surface coverage of removed PETN from MIFs was about 10. 8 ng/mm~. The developed SPR sensor allowed for the detection of PETN at concentration down to 10-~~ mol/L. A control experiment utilizing an analogue cyclotrimethylenetrinitramine （RDX） showed MIFs＇ good selectivity to PETN.

关键词： surface plasmon resonance (SPR) molecularly imprinted films (MIFs) pentaerythritoltetranitrate (PETN)

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An area-based position and attitude estimation for unmanned aerial vehicle navigation

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Science China(Technological Sciences) 2015年第5期58卷 916-926页

作者： LIU XiaoChun WANG Hou FU Dan YU QiFeng GUO PengYu LEI ZhiHui SHANG Yang College of Aerospace Science and Engineering National University of Defense Technology Hunan Key Laboratory of Videometrics and Vision Navigation institute of Aviation Equipment Naval Academy of Armament The Second Artillery Force of the Chinese People's Liberation Army Model Office at the First Academy of China Aerospace Science and Technology Corporation

The paper aims to challenge non-GPS navigation problems by using visual sensors and geo-referenced images. An area-based method is proposed to estimate full navigation parameters(FNPs), including attitude, altitude and horizontal position, for unmanned aerial vehicle(UAV) navigation. Our method is composed of three main modules: geometric transfer function, local normalized sobel energy image(LNSEI) based objective function and simplex-simulated annealing(SSA) based optimization algorithm. The adoption of relatively rich scene information and LNSEI, makes it possible to yield a solution robustly even in the presence of very noisy cases, such as multi-modal and/or multi-temporal images that differ in the type of visual sensor, season, illumination, weather, and so on, and also to handle the sparsely textured regions where features are barely detected or matched. Simulation experiments using many synthetic images clearly support noise resistance and estimation accuracy, and experimental results using 2367 real images show the maximum estimation error of 5.16(meter) for horizontal position, 9.72(meter) for altitude and 0.82(degree) for attitude.

关键词： GPS导航姿态估计水平位置无人机合成图像视觉传感器仿真实验无人飞行器

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A study on synchronization error accumulation over hop count for synchronization scheme of two-way packet exchange

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High Technology Letters 2012年第2期18卷 179-185页

作者：徐朝农 Xu Yongjun Wang Zhiguang Wang Feng Department of Computer Science and Technology China University of PetroleumBeijing 102249P.R.China institute of ComPuting Technology Chinese academy of SciencesBeijing 100008P.R.China naval Academy of armament Beijing100161China

Two-way packet exchange synchronization scheme has been widely used in wireless sensor networks. However, due to the fact that its synchronization error accumulates rapidly over hop count, its applications are greatly restricted. In this paper, the factors that cause the accumulation of synchronization error over hop count are investigated. Theoretical analysis shows that two factors including the clock drift and the asymmetry of two-way packet exchange, have distinct influences on synchronization error between two adjacent nodes. Further, the clock frequency order along synchronization path is found to be vital to the accumulation of synchronization error. The above three factors jointly determine the accumulation of synchronization error over hop count in wireless network. Theoretic results are also verified by three fine-grained experiments on wireless sensor network testbed. The conclusions can be used to decrease synchronization error for large-scale wireless network by careful network deployment. © by HIGH TECHNOLOGY LETTERS PRESS.

关键词：同步误差误差累积报文交换跳数无线传感器网络网络实验平台无线网络数据包交换

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JOUX三方密钥协商协议的形式化验证方法研究(英文)

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China Communications 2012年第3期9卷 153-163页

作者：祝烈煌张子剑王峰郭聪袁彩霞 Beijing Laboratory of Intelligent Information Technology School of Computer ScienceBeijing Institute of Technology naval Academy of armament Beijing University of Posts and Telecommunications

Security analysis of cryptographic protocols has been widely studied for many *** far as we know,we have not found any methods to effectively analyze group key exchange protocols for the three parties yet,which did not sacrifice the soundness of ***,Canetti and Herzog have proposed Universally Composable Symbolic Analysis(UCSA) of two-party mutual authentication and key exchange protocol which is based on the symmetric encryption *** scheme can analyze the protocols automatically and guarantee the soundness of ***,we discuss group key exchange protocol which is based on Joux Tripartite Diffie-Hellman(JTDH) using *** contribution is analyzing group key exchange protocol effectively without damaging the soundness of cryptography.

关键词： UCSA computationally sound JTDH group key exchange protocol

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