检索结果-内蒙古大学图书馆

IET International Radar Conference 2018, IRC 2018

作者： Xu, Feng Liu, Xin Liu, Li Wang, Chao Wang, YiFei National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing100076 China DFH Satellite Co. Ltd Beijing100094 China

Serious ground clutter is of significant influence for target detection in an airship-borne passive bistatic radar (ABPBR) using frequency modulated broadcasting signals. The authors propose a data segment processing scheme to recover the direct signal from multi-path clutter and suppress the multi-path in the surveillance channel in an ABPBR. Super exponential (SE) equaliser and sample matrix inversion algorithm are exploited to recover the transmitted signal and suppress the serious multi-path interference, respectively. It is shown that the proposed algorithms can accomplish the target detection task effectively by computer simulations. © 2019 Institution of Engineering and technology. All rights reserved.

关键词： Airships

来源：评论

学校读者我要写书评

暂无评论

Determination of the Backward Predictability Limit and Its Relationship with the Forward Predictability Limit

引用

Advances in Atmospheric sciences 2019年第6期36卷 669-677页

作者： Xuan LI Ruiqiang DING Jianping LI State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences College of Earth Science University of Chinese Academy of Sciences Laboratory for Regional Oceanography and Numerical Modeling Qingdao National Laboratory for Marine Science and Technology College of Global Change and Earth System Sciences (GCESS) Beijing Normal University

In this work, two types of predictability are proposed—forward and backward predictability—and then applied in the nonlinear local Lyapunov exponent approach to the Lorenz63 and Lorenz96 models to quantitatively estimate the local forward and backward predictability limits of states in phase space. The forward predictability mainly focuses on the forward evolution of initial errors superposed on the initial state over time, while the backward predictability is mainly concerned with when the given state can be predicted before this state happens. From the results, there is a negative correlation between the local forward and backward predictability limits. That is, the forward predictability limits are higher when the backward predictability limits are lower, and vice versa. We also find that the sum of forward and backward predictability limits of each state tends to fluctuate around the average value of sums of the forward and backward predictability limits of sufficient ***, the average value is constant when the states are sufficient. For different chaotic systems, the average value is dependent on the chaotic systems and more complex chaotic systems get a lower average value. For a single chaotic system,the average value depends on the magnitude of initial perturbations. The average values decrease as the magnitudes of initial perturbations increase.

关键词： nonlinear local Lyapunov exponent forward and backward predictability limit negative correlation average value

来源：评论

学校读者我要写书评

暂无评论

Calculation on External Heat Flux of a Space Camera

Calculation on External Heat Flux of a Space Camera

引用

第七届计算与信息科学国际学术会议

作者： Lian Xue Jiaqi Liu Lu Gao Zhiqi Liu Luping Zhang China National Key Laboratory of Science and Technology on Test Physics ＆Numerical Mathematics

In order to obtain accurate external heat flux data,the space system thermal simulation module in NX is used to solve the thermal analysis design problem on a camera in space flight *** effects of different time,different seasons and different orbital altitude on the external heat flux of spacecraft surface are *** calculation results show that for different seasons and different orbital altitudes,the variation laws of external heat flux on the same surface are basically the same,and there are only differences in *** differences are small,within 10 %;For the camera launched at different times of the day,the law of external heat flux changes is completely different,and difference in value is also very *** heat flux in the area exposed to the sun is 6.38 times that of the heat flux in the shadow *** results can be used to guide thermal design and calculate the temperature distribution of the *** the other hand,they provide reference for the design of other types of spacecraft with similar orbits.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Information Oriented Architecture of M&S Ecosystem

Information Oriented Architecture of M&S Ecosystem

引用

第三十八届中国控制会议

作者： Zheng ZHAO Chao ZHANG Jiaqi LIU LIUXin National Key Laboratory of Science&Technology on Test physics and Numerical mathematics

The paper conceives a new perspective of Architecture to build a ULS-liked M&S system. Under this perspective, Architecture of M&S ecosystems is developed under the "bottom-up" design pattern. To build the M&S ecosystem, we suggest a new concept of simulation resource name space such that all the simulation resource can be managed for the aim of sharing the resource by all simulation customer in the ecosystem. Also, the workflow of process of M&S ecosystems creating is provided.

关键词： Data Driven M&S simulation ecosystem

来源：评论

学校读者我要写书评

暂无评论

A New End-to-end Modulation Recognition Algorithm Based on Deep Learning

A New End-to-end Modulation Recognition Algorithm Based on D...

引用

International Conference on Signal Processing Proceedings (ICSP)

作者： Jingpeng Gao Fu Wang Lu Gao Xu Wang School of information and Communication Engineering Harbin Engineering University Harbin China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Institute of Space Long March Vehicle Beijing China

ISBN: (数字)9781728144801

ISBN: (纸本)9781728144818

To solve the problem of difficult modulation recognition of emitter signals at low signal-to-noise and low recognition rate caused by improper feature extraction, a new end-to-end modulation recognition algorithm based on deep learning is proposed. The algorithm can effectively recognize LFM, Costas, Frank code, and P1-P4 code. Firstly, an end-to-end modulation recognition network based on bi-directional long-short term memory is proposed to extract the time features of emitter signals for recognition. Then, to extract the space features of emitter signals, it explores a one-dimensional convolutional neural network structure. Finally, one-dimensional convolutional neural network and bi-directional long-short term memory are combined with pre-training and fine-tuning to accelerate the convergence speed and improve the recognition rate. The simulation results show that the recognition rate of the algorithm can reach 75.23% at the -6dB signal-to-noise ratio. It can also be used for modulation recognition in the mechanical field.

关键词： Feature extraction Modulation Training Signal to noise ratio Convolution Speech recognition Frequency modulation

来源：评论

学校读者我要写书评

暂无评论

A method for feature extraction based on SVD and machine learning 2

A method for feature extraction based on SVD and machine lea...

引用

2019 2nd International Conference on Advanced Materials, Intelligent Manufacturing and Automation, AMIMA 2019

作者： Mao, Wei Huang, Shuxian Liu, Xin Liu, Hongyan Liu, Jiaqi Shu, Yi National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics 100076 China Beijing Institute of Precision Mechatronics and Controls 100076 China Beijing Institute of Long March Vehicle 100076 China

By studying the shortcomings of feature, which extracted from Radar-Cross Section(RCS),using mathematical and statistical method, using the idea of extracting abstract features in image recognition and speech recognition by artificial intelligence for reference[2][3]. This paper explores the possibility of extracting abstract features of target's RCS sequence, and proposes an abstract feature extraction method of RCS sequence based on singular value decomposition(SVD) feature decomposition. Because of the poor interpretability of abstract features, four different machine learning algorithms are used to classify the extracted Abstract features. The experimental results show that the machine learning algorithm can classify different types of spatial objects with high accuracy, which shows that the RCS features of different spatial objects can be characterized by abstract features. © Published under licence by IOP Publishing Ltd.

关键词： Radar cross section

来源：评论

学校读者我要写书评

暂无评论

Topology Optimization of Complex Network based on NSGA-II

Topology Optimization of Complex Network based on NSGA-II

引用

IEEE Advanced Information technology, Electronic and Automation Control Conference (IAEAC)

作者： Zhang Bin Gan Zhi-chun Chen wen Hu Qiang-qiang Hou Jian-feng Departments of information and communication National University of Defense Technology China Science and Technology on Test Physics & Numerical Mathematic Laboratory China

This paper proposes a complex network topology optimization method based on NSGA-II with degrees and edges number unchanged. The method selects the elite parent networks by applying non-dominated layer sorting and congestion degree calculation through the network crossover and mutation operation to achieve maximum network efficiency and network invulnerability. Simulation analysis shows that the method can significantly improve the invulnerability and network efficiency of the initial networks at the same time. Optimizing the network efficiency makes the network connection show a negative correlation. The network presents a "multi-core decentralized" structure; optimizing the network invulnerability makes the connection show a positive correlation, the network presents a "close core and scattered periphery" structure; the cooperative optimization makes the network present a "tighter core and large periphery" structure, which is proved with good theoretical generality and practical application value.

关键词： Optimization Sociology Complex networks Correlation Topology

来源：评论

学校读者我要写书评

暂无评论

Complex forward scattering coefficient for signal characterisation

Complex forward scattering coefficient for signal characteri...

引用

IET International Radar Conference 2018, IRC 2018

作者： Chen, Jing Liu, Xiangrong Liu, Changjiang Dong, Xichao School of Information and Electronics Beijing Institute of Technology Beijing China Beijing Key Laboratory of Embedded Real-time Information Processing Technology Beijing China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics 100076 China

In this study, modelling and characteristics analysis of forward scattering coefficients and echoes are investigated. Traditional ground-target forward scattering signal model has not considered the impact of scattering phase;thus it is not accurate enough for describing air-target echoes. To solve this problem, a novel echo model was proposed based on the analytical deduction of complex forward scattering coefficient. The novel model separately expresses the target scattering characteristics and Doppler, greatly facilitating the theoretical analyses of echo characteristics. Then, theoretical and simulation investigations on the amplitude and phase characteristics of forward scattering echoes were made based on the complex forward scattering coefficient model. Theoretical explanations for the periodical fluctuation of far-field echo amplitude, periodical saltation of far-field echo phase, shadow blocking of near-field echo amplitude, and slow variation of near-field echo phase were given, respectively. Meanwhile, the boundary between near-field forward scattering and far-field forward scattering was quantitatively defined, which laid the theoretical foundation for the corresponding signal processing algorithms. Finally, with CST simulation results the accuracy of the echo model is verified and impacts of objects' real shapes are analysed. © 2019 Institution of Engineering and technology. All rights reserved.

关键词： Forward scattering

来源：评论

学校读者我要写书评

暂无评论

Design of W-band Sheet Beam EIK

Design of W-band Sheet Beam EIK

引用

Asia-Pacific Conference on Microwave

作者： Shuyuan Chen Jinliang Bai Ran Zhang Pei Zheng Jiaqi Liu Xin Liu Hongyan Liu Lu Gao National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

ISBN: (数字)9781728135175

ISBN: (纸本)9781728135182

Microwave tube is a vacuum electron device which can be used for amplification in the microwave frequency range. Sheet beam Extended Interaction Klystron (EIK) is an attractive Millimeter Waves amplifier because of its compact configuration, small voltage and high gain per unit length. In this paper, RF structure and the whole tube for W-band sheet beam EIK has been designed. A new and effective method of designing and studying W-band sheet beam EIK is presented in this paper. In order to get the same output power, several kinds of W-band sheet beam EIK are designed and compared. By optimizing the position of cavities, the output power can achieve 30 kW, which is calculated by threedimensional particle in cell (3D-PIC) software. It is a powerful basis for the subsequent study of sheet beam EIK.

关键词： Power generation Klystrons Power amplifiers physics mathematics Urban areas

来源：评论

学校读者我要写书评

暂无评论

Modulation recognition of emitter signals based on SDAE-ODCNN

Modulation recognition of emitter signals based on SDAE-ODCN...

引用

IET International Radar Conference (IET IRC 2020)

作者： X. Wang J. Gao L. Gao F. Wang Harbin Engineering University College of Information and Communication Engineering Harbin China Beijing Institute of Space Long March Vehicle National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

In order to improve the recognition rate of emitter signals modulation under low signal noise ratio (SNR), an end-to-end method based on the stacked denoising autoencoder (SDAE) - one dimensional convolutional neural network (ODCNN) is proposed in this paper. The SADE-ODCNN is designed in this method and trained through a two-step training. In the SDAE-ODCNN model, the encoder of the SDAE can extract the denoised and compressed features of the received emitter signals. Then the ODCNN can further extract features to realize the recognition. The simulation results show that the average recognition rate of the method can reach 0.94 under 0dB. Thus the proposed method has a good application in the field of emitter signals modulation recognition.

关键词： radar computing modulation feature extraction neural nets image denoising learning (artificial intelligence) image classification

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：