检索结果-内蒙古大学图书馆

International Conference on Recent Advancements in Electrical, Electronics and Control Engineering (ICONRAEeCE)

作者： Runle Du Jiaqi Liu Yonghai Wang Gang Meng Chenyang Mu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics China

Large-angle attitude maneuver is common during the mission of spacecrafts, such as aligning to star to calibrate navigation system. Published works on attitude tracking always focus on optimizing the time and fuel cost, neglecting the smoothness requirement and angular speed limitations. In this paper, a nonlinear control algorithm is prompted for smooth transition in large-angle attitude maneuver. A nonlinear filter is added to the attitude feedback control loop, to carry out angular speed control in large-angle maneuvers. Simulation results demonstrated the effectiveness and reliability of proposed approach.

关键词： Attitude control Space vehicles mathematical model Equations Switches Fuels

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

Dual-band checkerboard plasma electromagnetic surface for radar cross section reduction

Dual-band checkerboard plasma electromagnetic surface for ra...

引用

IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP)

作者： Qiang Xu Zhifeng Li Jinjun Mo National University of Defense Technology Changsha China National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematical Beijing China

ISBN: (纸本)9781538616093

Radar cross section (RCS) can be reduced along the principal planes by applying electromagnetic band gap (EBG) structures. Checkerboard plasma electromagnetic surface (PES), combining with EBG and plasma layer, can realize a narrow band near 3 GHz and a wide band 10-dB radar cross section reduction (RCSR) covered X-band, by redirecting the scattered fields towards four quadrants. Bistatic RCS of the checkerboard PES is simulated and the results compared to the corresponding perfect electric conductor (PEC) surface show that the maxima of the bistatic RCS pattern are reduced by 5.4 dB at fixed frequency 10 GHz.

关键词： Plasmas Periodic structures Metamaterials Electromagnetics Radar cross-sections Electromagnetic scattering

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

Low-Sidelobe Pattern Synthesis for Sparse Conformal Arrays Based on Multiagent Genetic Algorithm

Low-Sidelobe Pattern Synthesis for Sparse Conformal Arrays B...

引用

2022 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio science Meeting, AP-S/URSI 2022

作者： Liu, Ganyu Zhu, Hailiang Wang, Kai Qiu, Yuwei Mou, Jinchao Zheng, Pei Wei, Gao Northwestern Polytechnical University Xi'an710129 China The Beijing Research Institute of Telemetry Beijing100094 China The National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing100076 China

ISBN: (数字)9781665496582

ISBN: (纸本)9781665496582

In this paper, multiagent genetic algorithm (MAGA) is firstly applied to tackle the synthesis of conformal sparse array, a constrained multi-objective optimization problem. Moreover, a model considered low peak sidelobe level (PSLL) is given for conformal sparse array synthesis. For the antenna array deployed on a quadric surface, the PSLL can be reduced by obtaining the optimal antenna element arrangement. An example of 256-element array synthesis with a 56% sparse rate proves MAGA as an effective optimization tool for conformal sparse arrays in low computational cost. © 2022 IEEE.

关键词： Genetic algorithms

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

Detecting Changes in Precipitation and Temperature Extremes over China Using a Regional Climate Model with Water Table Dynamics Considered

引用

Atmospheric and Oceanic science Letters 2014年第2期7卷 103-109页

作者： QIN Pei-Hua XIE Zheng-Hui WANG Ai-Wen The National Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences School of Applied Science Beijing Information and Science Technology University

Simulations were conducted with the regional climate model RegCM incorporating water table dynamics from 1 September 1982 to 28 August 2002 to detect precipitation and temperature extremes. Compared with observed r10(number of days with precipitation ≥ 10 mm d–1), RegCM3_Hydro(the regional climate model with water table dynamics considered) simulated rain belts, including those in southern China and the middle and lower reaches of the Yangtze River, and provided data for arid to semi-arid areas such as the Heihe River Basin in northwestern China. RegCM3_Hydro indicated a significant increasing trend of r95p(days with daily precipitation greater than the 95th percentile of daily amounts) for the Yangtze, Yellow, and Pearl River basins, consistent with r95p observations. The Haihe River Basin was also chosen as a specific case to detect the effect of groundwater on extreme precipitation using peaks over threshold(POT)-based generalized Pareto distribution(GPD) with parameters estimated by the L-moment method. Quantile plots showed that all but a few of the plotted points were distributed near diagonal lines and the modeled data fitted well with the samples. Finally, the effects of water table dynamics on temperature extremes were also evaluated. In the Yellow River Basin and Songhuajiang River Basin, the trends of the number of warm days(TX95n) from RegCM3_Hydro matched observed values more closely when water table dynamics were considered, and clearly increasing numbers of warm days from 1983 to 2001 were detected.

关键词： climatic extreme groundwater runoff river basin regional climate

来源：评论

学校读者我要写书评

暂无评论

Ellipse Fitting Based on Neural Network Optimization 41

Ellipse Fitting Based on Neural Network Optimization

引用

第41届中国控制会议

作者： Chenrong Long Peng Liu Qinglei Hu School of Automation Science and Electrical Engineering Beihang University National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics Beijing Institute of Space Long March Vehicle School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China.

ISBN: (数字)9789887581536

ISBN: (纸本)9781665482561

Ellipse fitting is to estimate the parameters of the ellipse from a set of coplanar points,but the geometric distance from the plane point to the elliptic curve is difficult to calculate *** paper proposes a neural network optimization-based algorithm to estimate the geometric distances from plane points to elliptic curves to solve the ellipse fitting ***,the neural network is firstly applied to train the geometric distance between the plane point and the standard ellipse,and then obtain the geometric distance between the plane point and the general ellipse through the rotation and translation ***,use minimizing the sum of the Euclidean distances from the plane point to the elliptic curve as the objective function,and finally use the gradient descent method to iteratively solve the ellipse ***,the proposed method avoids the direct algebraic solution of the geometric distance from the plane point to the elliptic curve and the performance of the algorithm to gether with its robustness to noise are analysed via numerical simulation.

关键词： Ellipse Fitting Coplanar Points Geometric Distance Neural Network Optimization

来源：评论

学校读者我要写书评

暂无评论

An Absorptive/Transmissive Frequency Selective Surface with Wide Transmission Band and Low Insertion Loss

An Absorptive/Transmissive Frequency Selective Surface with ...

引用

International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Hang Song Jiaqi Liu Shengjun Zhang National Key Laboratory of Science & Technology on Test Physics and Numerical Mathematics Beijing China

The Absorptive/transmissive Frequency Selective Surface (ATFSS) is a multi-layer composite periodic structure with out-of-band absorption and in-band transmission characteristics, usually composed of a lossy resistive sheet (RS) and a lossless bandpass FSS. In this paper, an equivalent circuit method based on transmission line theory was used to design the ATFSS with idea of higher frequencies for transmission and lower frequencies for absorption, as well as the impedance conditions for satisfying wave transmission and absorption. Furthermore, the S-parameters was fitted, which verifies the design concept. Finally, the simulation was performed with numerical method. It is shown from the simulation that the broadband absorption of the ATFSS ranges from 2.00 GHz to 6.29 GHz, and the broadband transmission ranges from 8.46 GHz to 11.32 GHz with an insertion loss of less than 1 dB.

关键词： Frequency selective surfaces Absorption Insertion loss Power system stability Propagation losses Stability analysis Broadband communication

来源：评论

学校读者我要写书评

暂无评论

A novel GCV-based criterion for parametric PSF estimation

A novel GCV-based criterion for parametric PSF estimation

引用

International Conference on Signal Processing Proceedings (ICSP)

作者： Feng Xue Jiaqi Liu Zhifeng Li Gang Meng National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

ISBN: (纸本)9781479921898

We propose a generalized cross validation (GCV) as a novel criterion for estimating a point spread function (PSF) from the degraded image only. The PSF is obtained by minimizing this new objective functional over a family of Wiener processings. Based on this estimated PSF, we then perform deconvolution using our recently developed SURE-LET algorithm. The GCV-based criterion is exemplified with a number of parametric PSF, involving a scaling factor that controls the blur size. A typical example of such parametrization is the Gaussian kernel. The experimental results demonstrate that the GCV minimization yields highly accurate estimates of the PSF parameters, which also result in a negligible loss of visual quality, compared to that obtained with the exact PSF. The highly competitive results outline the great potential of developing more powerful blind deconvolution algorithms based on this criterion.

关键词： Optical filters Abstracts Estimation Fluorescence Noise reduction Integrated optics Optical imaging

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：