检索结果-内蒙古大学图书馆

Recent developments on the lagrangian and remapping methods for compressible fluid flows

International Conference on numerical Methods for Hyperbolic Equations: Theory and Applications

作者： Juan, Cheng Shu, Chi-Wang National Key Laboratory of Science and Technology on Computational Physics Institute of Applied Physics and Computational Mathematics China Division of Applied Mathematics Brown University United States

ISBN: (纸本)9780415621502

The Lagrangian method and the Arbitrary Lagrangian-Eulerian method (ALE) are widely used in many fields, especially for multi-material flow simulations, due to their distinguished advantage in capturing material interfaces automatically. In this paper we give a short survey on our recent research on the Lagrangian scheme and the remapping method, both of which constitute essential and important components of the ALE method. Specifically, we first introduce a class of high order Lagrangian schemes which are based on Essentially Non-Oscillatory (ENO) and Weighted Essentially Non-Oscillatory (WENO) reconstructions. The schemes are constructed both on straight-line quadrilateral meshes and on curvilinear quadrilateral meshes. Meanwhile, two approaches for high order time discretization in the Lagrangian scheme are investigated, namely, the Total Variation Diminishing (TVD) Runge-Kutta time discretization and the Lax-Wendroff (LW) type time discretization. Next, we give a class of cell-centered Lagrangian schemes with the properties of both conservation and spherical-symmetry-preserving in two-dimensional cylindrical coordinates. After that, we summarize a high order conservative ENO remapping algorithm. At last, several numerical examples are shown to further demonstrate the performance of these schemes. © 2013 Taylor & Francis Group, London.

关键词： Lagrange multipliers

来源：评论

学校读者我要写书评

暂无评论

A Direct Position Determination Method for Four-station TDOA Location System

A Direct Position Determination Method for Four-station TDOA...

引用

Signal, Information and Data Processing (ICSIDP), IEEE International Conference on

作者： Sun-Rui Qi Chen-Shun Yuan Bai-Jin Liang Gao-Lu Li-Hu Sun-Heng BEIJING INSTITUTE OF SPACE LONG MARCH VEHICLE National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

ISBN: (数字)9781728123455

ISBN: (纸本)9781728123462

Aiming at the four-station networked TDOA (Time Difference of Arrival) localization system, a direct location method based on electronic elevation map search is proposed, the Geometric Dilution Precision (GDOP) is derived, and the factors affecting the location accuracy are analyzed. The location method under real conditions is also simulated, and its feasibility is demonstrated, which provides a new engineering method for networked TDOA location.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Improving the simulation of terrestrial water storage anomalies over China using a Bayesian model averaging ensemble approach

引用

Atmospheric and Oceanic science Letters 2018年第4期11卷 322-329页

作者： LIU Jian-Guo JIA Bing-Hao XIE Zheng-Hui SHI Chun-Xiang School of Mathematics and Computational Science and Key Laboratory of Intelligent Control Technology for Wuling-Mountain Ecological Agriculture in Hunan Province Huaihua University State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences National Meteorological Information Center China Meteorological Administration

The ability to estimate terrestrial water storage(TWS)is essential for monitoring hydrological extremes(e.g.,droughts and floods)and predicting future changes in the hydrological ***,inadequacies in model physics and parameters,as well as uncertainties in meteorological forcing data,commonly limit the ability of land surface models(LSMs)to accurately simulate *** this study,the authors show how simulations of TWS anomalies(TWSAs)from multiple meteorological forcings and multiple LSMs can be combined in a Bayesian model averaging(BMA)ensemble approach to improve monitoring and *** using three forcing datasets and two LSMs were conducted over China's Mainland for the period 1979–*** the simulations showed good temporal correlations with satellite observations from the Gravity Recovery and Climate Experiment during 2004–*** correlation coefficient ranged between 0.5 and 0.8 in the humid regions(e.g.,the Yangtze river basin,Huaihe basin,and Zhujiang basin),but was much lower in the arid regions(e.g.,the Heihe basin and Tarim river basin).The BMA ensemble approach performed better than all individual member *** captured the spatial distribution and temporal variations of TWSAs over China's Mainland and the eight major river basins very well;plus,it showed the highest R value(>0.5)over most basins and the lowest root-mean-square error value(<40 mm)in all basins of *** good performance of the BMA ensemble approach shows that it is a promising way to reproduce long-term,high-resolution spatial and temporal TWSA data.

关键词： Terrestrial water storage anomalies multi-forcing and multi-model ensemble simulation Bayesian model averaging spatiotemporal variation uncertainty

来源：评论

学校读者我要写书评

暂无评论

An Improved Adaptive Pulse Compression Algorithm Based on Linear Frequency Modulation Signal

An Improved Adaptive Pulse Compression Algorithm Based on Li...

引用

Signal, Information and Data Processing (ICSIDP), IEEE International Conference on

作者： Jinliang Bai Peng Qin Hu Li Ran Zhang Xinyu Zhang National key laboratory of science and technology on test physics and numerical mathematics Beijing Institute of Space Long March Vehicle Beijing China

ISBN: (数字)9781728123455

ISBN: (纸本)9781728123462

In this paper, the radar signal is optimized based on the pulse compression repair (PCR) algorithm, which mainly reduces the computational amount to makes it more advantageous to achieve. The main idea is to implement PCR in a parallel way. The method of implementing parallelism is well known, that is, the signal is segmented, and different segmentation methods can be adopted according to different signal models. In this paper, the chirp signal is mainly processed by decimation and segmentation, and some intrinsic benefits of the performance and computational balance of the proposed method are discussed.

关键词：

来源：评论

学校读者我要写书评

暂无评论

A Binary Sparrow-Hybridized Beluga Whale Optimization Algorithm for Jamming Task Assignment 6

A Binary Sparrow-Hybridized Beluga Whale Optimization Algori...

引用

6th IEEE International Conference on Electronic Information and Communication technology, ICEICT 2023

作者： Shen, Chen Gao, Jingpeng Jiang, Zhiye Zhang, Tianran Chen, Geng College of Information and Communication Engineering Harbin Engineering University Harbin150050 China Beijing Institute of Space Long March Vehicle National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China Beijing Institute of Electronic System Engineering Beijing100854 China

ISBN: (纸本)9798350399059

In the context of non-cooperative electronic countermeasures, the problem of formulating effective jamming task assignments arises due to insufficient collaborative jamming resources. This paper proposes a binary sparrow- hybridized beluga whale optimization algorithm based on jamming task assignments. The algorithm combines the binary sparrow search algorithm(BSSA) and the binary beluga whale optimization(BBWO), which is set with multi-dimensional constraints in the time, frequency and spatial domains. To achieve the optimal strategy for collaborative interference task assignment, a fitness function is constructed using both radar coverage and the signal-to-jamming ratio received by each radar. When the number of UAVs is 7 and the number of radars is 10, the simulation results show that the optimization speed and accuracy of the proposed algorithm are significantly higher than the BSSA and BBWO. Therefore, the algorithm has good coverage and performance in the field of jamming task assignments. © 2023 IEEE.

关键词： Optimization

来源：评论

学校读者我要写书评

暂无评论

Broadband Dual-Polarized Antenna with Enhanced Front-To-Back Ratio Using Meta-surface

Broadband Dual-Polarized Antenna with Enhanced Front-To-Back...

引用

Asia-Pacific Conference on Microwave

作者： Pei Zheng Yuwei Qiu Jinliang Bai Ziwei Xu Xin Liu Jiaqi Liu Jun Li Shuo Zhang Hailiang Zhu Gao Wei National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China Northwestern Polytechnical University Xi'an Shaanxi China

ISBN: (数字)9781728135175

ISBN: (纸本)9781728135182

A novel broadband dual-polarized dipole antenna with enhanced front-to-back ratio is proposed. By placing metasurface around the radiators, the proposed dipole antenna exhibits wide impedance bandwidth (S11&S22 ≤ -12dB) of 52% from 0.675 to 1.15 GHz, covering the lower frequency band (0.69~0.96GHz) of base station antenna. Simulated results show that the front-to-back ratio can be increased by 4-5dB after adding the meta-surface, radiation pattern with enhanced frontto-back ratio (FBR) higher than 20dB were achieved over the operating frequency range. In addition, the antenna architecture is simple and easy to fabricate in base stations that can be used in modern mobile communication systems.

关键词： Dipole antennas Broadband antennas Antenna radiation patterns Probes Broadband communication Bandwidth

来源：评论

学校读者我要写书评

暂无评论

Fast Data Fusion Algorithm for Tracking Maneuvering Target by Vehicle Formation

Fast Data Fusion Algorithm for Tracking Maneuvering Target b...

引用

IEEE Radar Conference

作者： Runle Du Jiaqi Liu Yonghai Wang Zhifeng Li Chunyue Gao National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing Aero-Top Hi-Tech Corporation Ltd.

ISBN: (纸本)9781467357920

When multiple flying vehicles with bearing-only tracking collaborate in locating a target, observation data fusion is required to compensate the drift of navigation system, the noise from observation system, and the unknown maneuvering of target object. Kalman Filtering of nonlinear observation data needs a huge amount of computation, and will cause trouble to onboard embedded computing systems. Least Squared Error (LSE) can process nonlinear measurements at high speed, but the observation noise may be amplified due to the intrinsic deficiency. In this paper, a Fast Data Fusion algorithm is proposed. It combined these two methodologies. LSE is used as the preprocessing stage to build a coarse estimation and Kalman Filtering is used to further eliminate noises from preprocessed estimations. Simulation results show that, proposed method uses no more than 3% of computation time of Kalman Filtering and achieved similar or even better target locating precision.

关键词： Formation Flying Bearing-only Tracking Passive Target Location Fast Data Fusion Kalman Filtering

来源：评论

学校读者我要写书评

暂无评论

Parallel pipeline algorithm of real time star map preprocessing

Parallel pipeline algorithm of real time star map preprocess...

引用

Chinese Society for Optical Engineering Conferences, CSOE 2016

作者： Wang, Hai-Yong Qin, Tian-Mu Liu, Jia-Qi Li, Zhi-Feng Li, Jian-Hua School of Aeronautics and Astronautics Beihang University Beijing100083 China Beijing Institute of Space Long March Vehicle Beijing100076 China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematical Beijing100076 China

ISBN: (纸本)9781510610118

To improve the preprocessing speed of star map and reduce the resource consumption of embedded system of star tracker, a parallel pipeline real-time preprocessing algorithm is presented. The two characteristics, the mean and the noise standard deviation of the background gray of a star map, are firstly obtained dynamically by the means that the intervene of the star image itself to the background is removed in advance. The criterion on whether or not the following noise filtering is needed is established, then the extraction threshold value is assigned according to the level of background noise, so that the centroiding accuracy is guaranteed. In the processing algorithm, as low as two lines of pixel data are buffered, and only 100 shift registers are used to record the connected domain label, by which the problems of resources wasting and connected domain overflow are solved. The simulating results show that the necessary data of the selected bright stars could be immediately accessed in a delay time as short as 10us after the pipeline processing of a 496×496 star map in 50Mb/s is finished, and the needed memory and registers resource total less than 80kb. To verify the accuracy performance of the algorithm proposed, different levels of background noise are added to the processed ideal star map, and the statistic centroiding error is smaller than 1/23 pixel under the condition that the signal to noise ratio is greater than 1. The parallel pipeline algorithm of real time star map preprocessing helps to increase the data output speed and the anti-dynamic performance of star tracker. © 2017 SPIE.

关键词： Pipelines

来源：评论

学校读者我要写书评

暂无评论

A High Temperature Resistant Broadband Metamaterial Absorber

A High Temperature Resistant Broadband Metamaterial Absorber

引用

International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Yinfang Xu Jiaqi Liu Lu Gao Xia Ai National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics Beijing Institute of Space Long March Vehicle Beijing China

Based on high temperature resistant silicon dioxide(SiO 2 ) and silicon carbide(SiC) materials, a high temperature resistant broadband meta material absorber was designed in this paper. The absorber consists of two layers of SiC pattern, three layers of $\text{SiO}_{2}$ transmission medium, and a bottom layer of low resistance SiC thin film reflection layer. The simulation results show that the absorption rate of the absorber exceeds 90% in the frequency range of 3.46-18.37GHz, and the relative absorption bandwidth is 136.6%. The absorber device also has the characteristics of low process implementation difficulty, polarization insensitivity, and wide-angle absorption. Therefore, it has potential application value in fields such as radar imaging, stealth, and communication technology.

关键词：

来源：评论

学校读者我要写书评

暂无评论

1-bit Coding Metasurface for Wideband RCS Reduction

1-bit Coding Metasurface for Wideband RCS Reduction

引用

International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Yinfang Xu Jiaqi Liu Lu Gao Xia Ai Zhongjie Zhang Huan Liang National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics Beijing Institute of Space Long March Vehicle Beijing China

This paper achieve efficient RCS reduction over a wide frequency range by exploiting the reflection properties of the coding metasurface. The metasurface consists of “0” cells and “1” cells, and the reflection phase difference is close to 180° over a wide frequency range. By designing the spatial random coding arrangement of “0” units and “1” units, the electromagnetic waves incident on the metasurface form diffuse reflection, so as to achieve the purpose of broadband RCS reduction. The simulation results show that when the incident wave is irradiated vertically, the metasurface can basically achieve a RCS reduction of more than 10dB in a wide frequency band of 10-20.5GHz compared to a metal plate of the same size. In the case of oblique incidence, the RCS reduction still has a good effect, which is basically the same as the curve at normal incidence, and has the characteristics of wide-angle incidence RCS reduction. The reduced bandwidth of the broadband RCS of the coding metasurface is basically consistent with the 10 dB polarization bandwidth of the cell structure. The design of the metasurface is simple and efficient, so it has great application potential in stealth new technologies and new materials.

关键词： Electric potential Simulation Electromagnetic scattering Metals Metasurfaces Computational electromagnetics Reflection

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：