检索结果-内蒙古大学图书馆

IET International Radar Conference 2018, IRC 2018

作者： Bai, JinLiang Jiang, ZhiYe Wang, Feng Zhou, Yi Sun, Heng National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China Array and Information Processing Laboratory College of Computer and Information Hohai University West Focheng Road No. 8 Jiangning District Nanjing China

Fractionally spaced super-exponential (FSSE) algorithm has the disadvantage of computational complexity since it exploits high-order statistics explicitly. The authors propose a dimension degradation technique for FSSE when it is applied to the equalisation of a sparse channel in accordance with the relationship between the coefficients of the cross fourth-order cumulant (CFOC) in FSSE and the channel impulse response. They implement partial updating on the prominent coefficients of the CFOC with all the small coefficients remaining unchanged. The computational complexity of the modified FSSE reduces significantly with an acceptable performance loss, and its performance is validated via numerical simulations. © This is an open access article published by the IET under the Creative Commons Attribution License (http://***/licenses/by/3.0/)

关键词： Computational complexity

来源：评论

学校读者我要写书评

暂无评论

SIP-IFVM: A time-evolving coronal model with an extended magnetic field decomposition strategy

arXiv

引用

arXiv 2025年

作者： Wang, Hao P. Yang, Li P. Poedts, S. Lani, A. Zhou, Yu H. Gao, Yu H. Linan, L. Lv, Jia K. Baratashvili, T. Guo, Jing H. Rong, L. Su, Z. Li, Cai X. Zhang, M. Wei, Wen W. Yang, Y. Li, Yu C. Ma, Xin Y. Husidic, E. Jeong, H.-J. Mahdi, Najafi Z. Wang, J. Schmieder, B. Centre for Mathematical Plasma-Astrophysics Department of Mathematics KU Leuven Celestijnenlaan 200B Leuven3001 Belgium State Key Laboratory of Space Weather Chinese Academy of Sciences Beijing100190 China Institute of Physics University of Maria Curie-Sklodowska ul. Radziszewskiego 10 Lublin20-031 Poland Von Karman Institute For Fluid Dynamics Waterloosesteenweg 72 Sint-Genesius-Rode Brussels1640 Belgium School of Earth and Space Sciences Peking University Beijing100871 China Beijing Institute of Applied Meteorology Beijing100029 China School of Astronomy and Space Science Key Laboratory of Modern Astronomy and Astrophysics Nanjing University Nanjing210023 China SIGMA Weather Group State Key Laboratory for Space Weather National Space Science Center Chinese Academy of Sciences Beijing100190 China Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology Center for Intense Laser Application Technology College of Engineering Physics Shenzhen Technology University Shenzhen518118 China Space Sciences Laboratory University of California BerkeleyCA94720 United States School of Mathematical Sciences Nanjing Normal University Nanjing210023 China Ministry of Education Key Laboratory of NSLSCS China College of Earth and Planetary Sciences University of Chinese Academy of Sciences Beijing100049 China School of Systems Science Beijing Normal University Beijing100875 China Meudon Principal F-92195 Cedex France SUPA School of Physics & Astronomy University of Glasgow GlasgowG12 8QQ United Kingdom

Time-evolving magnetohydrodynamic (MHD) coronal modeling, driven by a series of time-dependent photospheric magnetograms, represents a new generation of coronal simulations. This approach offers greater realism compared to traditional coronal models constrained by a static magnetogram. However, its practical application is seriously limited by low computational efficiency and poor numerical stability. Therefore, we propose an extended magnetic field decomposition strategy and implement it in the implicit MHD model to develop a coronal model that is both efficient and numerically stable enough for simulating the long-term evolutions of the global corona. The traditional decomposition strategies split the magnetic field into a time-invariant potential field and a time-dependent component B1. It works well for quasi-steady-state coronal simulations where |B1| is typically small. However, as the inner-boundary magnetic field evolves, |B1| can grow significantly larger and its discretization errors often lead to nonphysical negative thermal pressure, ultimately causing the code to crash. In this paper, we mitigate such undesired situations by introducing a temporally piecewise-constant variable to accommodate part of the non-potential field and remain |B1| consistently small throughout the simulations. We incorporate this novel magnetic field decomposition strategy into our implicit MHD coronal model and apply it to simulate the evolution of coronal structures within 0.1 AU over two solar-maximum Carrington rotations. The results show that this coronal model effectively captures observations and performs more than 80 times faster than real time using only 192 CPU cores, making it well-suited for practical applications in simulating the time-evolving corona. © 2025, CC BY-NC-SA.

关键词： Electric corona

来源：评论

学校读者我要写书评

暂无评论

Insect wing-beat frequency automatic extraction and experimental verification with a Ku-band insect radar system

Insect wing-beat frequency automatic extraction and experime...

引用

IET International Radar Conference 2018, IRC 2018

作者： Zhang, Tianran Liu, XiangRong Hu, Cheng Wang, Rui Liu, Changjiang Li, Wenqing Radar Research Laboratory School of Information and Electronics Beijing Institute of Technology Beijing100081 China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing100076 China Key Laboratory of Electronic and Information Technology in Satellite Navigation Beijing Institute of Technology Ministry of Education Beijing100081 China

The wing-beat frequency is one of the most important behavioural parameters of migratory insects and is widely used to distinguish insect species due to the diversity of wing-beat frequency among different species. Traditional insect radar has been able to achieve automatic extraction of the wing-beat frequency. However, its low-range resolution and fixed threshold detection may cause false alarms and reduce the precision of wing-beat frequency. The authors' Ku-band insect radar system enables high-resolution, full-polarised detection of insects, but has not achieved automatic extraction of wing-beat frequency yet. The authors propose an insect wing-beat frequency automatic extraction algorithm based on a Ku-band insect radar system. The algorithm adopts the constant false alarm rate detector and tracks the association algorithm to get target echo automatically and combines the amplitude spectrum method and the phase spectrum method to achieve wing-beat frequency extraction. The authors carried out the outfield experiment using the radar system and used the collected data to test the proposed algorithm. The experiment results confirm that the algorithm can extract the wing-beat frequency of insects automatically based on the Ku-band insect radar system, which can improve system efficiency. © 2019 Institution of Engineering and technology. All rights reserved.

关键词： Errors

来源：评论

学校读者我要写书评

暂无评论

Performance analysis of one-step prediction-based cognitive jamming in jammer-radar countermeasure model

Performance analysis of one-step prediction-based cognitive ...

引用

IET International Radar Conference 2018, IRC 2018

作者： Gao, Lu Liu, Li Cao, Yang Wang, Shangyue You, Shixun National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China DFH Satellite Co. Ltd Beijing China Harbin Engineering University 145 Nantong Street Nangang District Harbin China

Strong adaptive radar, such as cognitive radar (CNR), can perform various missions while ensuring its own security in electronic warfare, via detecting environments and changing the radar parameters in real time. Unfortunately, most of the current military countermeasures, such as jamming-based electronic countermeasures, have rarely been related to jamming for CNR. Since the behaviours of radar in the traditional design of the jammer-radar scenario are always static, it is easy to create a subjective or local optimal jamming effect. In order to dynamically analyse the execution process of a complete jamming radar mission, this work establishes an equivalent attack-defence game in which the radar is regarded as a defence decision agent, and the jammer is an attack decision agent. The attributes of the game's players, the rules of the game, and the conditions for the end of the game are set clearly by setting reasonable parameters. After searching for antagonism strategies by exhaustive method, it can be found that the survivability of the predictive cognitive jamming is much stronger than that of the normal jamming based on real-time sampling data of radars. This conclusion is demonstrated through a 1 ms simulation of the game process. © This is an open access article published by the IET under the Creative Commons Attribution License (http://***/licenses/by/3.0/)

关键词： Jamming

来源：评论

学校读者我要写书评

暂无评论

Tensor-Networks-based Learning of Probabilistic Cellular Automata Dynamics

arXiv

引用

arXiv 2024年

作者： Casagrande, Heitor P. Xing, Bo Munro, William J. Guo, Chu Poletti, Dario Science Mathematics and Technology Cluster Singapore University of Technology and Design 8 Somapah Road Singapore487372 Singapore Okinawa Institute of Science Technology Graduate University Onna-son Okinawa904-0495 Japan Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Department of Physics and Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Changsha410081 China EPD Pillar Singapore University of Technology and Design 8 Somapah Road Singapore487372 Singapore Centre for Quantum Technologies National University of Singapore Singapore117543 Singapore MajuLab CNRS-UNS-NUS-NTU International Joint Research Unit UMI 3654 Singapore Singapore

Algorithms developed to solve many-body quantum problems, like tensor networks, can turn into powerful quantum-inspired tools to tackle problems in the classical domain. In this work, we focus on matrix product operators, a prominent numerical technique to study many-body quantum systems, especially in one dimension. It has been previously shown that such a tool can be used for classification, learning of deterministic sequence-to-sequence processes and of generic quantum processes. We further develop a matrix product operator algorithm to learn probabilistic sequence-to-sequence processes and apply this algorithm to probabilistic cellular automata. This new approach can accurately learn probabilistic cellular automata processes in different conditions, even when the process is a probabilistic mixture of different chaotic rules. In addition, we find that the ability to learn these dynamics is a function of the bit-wise difference between the rules and whether one is much more likely than the other. Copyright © 2024, The Authors. All rights reserved.

关键词： Tensors

来源：评论

学校读者我要写书评

暂无评论

The Relationship between Deterministic and Ensemble Mean Forecast Errors Revealed by Global and Local Attractor Radii

引用

Advances in Atmospheric sciences 2019年第3期36卷 271-278,339页

作者： Jie FENG Jianping LI Jing ZHANG Deqiang LIU Ruiqiang DING School of Meteorology University of Oklahoma College of Global Change and Earth System Science (GCESS) Beijing Normal University Laboratory for Regional Oceanography and Numerical Modeling Qingdao National Laboratory for Marine Science and Technology Cooperative Institute for Research in the Atmosphere GSD/ESRL/OAR/NOAA Fujian Meteorological Observatory Wuyishan National Park Meteorological Observatory State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Plateau Atmosphere and Environment Key Laboratory of Sichuan Province Chengdu University of Information Technology

It has been demonstrated that ensemble mean forecasts, in the context of the sample mean, have higher forecasting skill than deterministic(or single) forecasts. However, few studies have focused on quantifying the relationship between their forecast errors, especially in individual prediction cases. Clarification of the characteristics of deterministic and ensemble mean forecasts from the perspective of attractors of dynamical systems has also rarely been involved. In this paper, two attractor statistics—namely, the global and local attractor radii(GAR and LAR, respectively)—are applied to reveal the relationship between deterministic and ensemble mean forecast errors. The practical forecast experiments are implemented in a perfect model scenario with the Lorenz96 model as the numerical results for verification. The sample mean errors of deterministic and ensemble mean forecasts can be expressed by GAR and LAR, respectively, and their ratio is found to approach2^(1/2) with lead time. Meanwhile, the LAR can provide the expected ratio of the ensemble mean and deterministic forecast errors in individual cases.

关键词： attractor radius ensemble forecasting ensemble mean forecast error saturation

来源：评论

学校读者我要写书评

暂无评论

Anthropogenic Influences on the Extremely Dry and Hot Summer of 2020 in Southern China and Projected Changes in the Likelihood of the Event

SSRN

引用

SSRN 2024年

作者： Wang, Kaixi Zheng, Zhiyuan Zhu, Xian Dong, Wenjie Tett, Simon F.B. Dong, Buwen Zhang, Wenxia Lott, Fraser C. Bu, Lulei Wang, Yumiao Li, Huixin Nanding, Nergui Freychet, Nicolas Wang, Dongqian Qiao, Shaobo Ministry of Education Sun Yat-sen University Zhuhai China Zhuhai Branch State Key Laboratory of Earth Surface Process and Resource Ecology Advanced Institute of Natural Sciences Beijing Normal University Zhuhai China School of Geosciences University of Edinburgh Edinburgh United Kingdom National Centre for Atmospheric Science Department of Meteorology University of Reading Reading United Kingdom State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Met Office Hadley Centre ExeterEX1 3PB United Kingdom Department of Atmospheric and Oceanic Sciences Institute of Atmospheric Sciences IRDR International Center of Excellence on Risk Interconnectivity and Governance on Weather/Climate Extremes Impact and Public Health Fudan University Shanghai China School of Hydrology and Water Resources Nanjing University of Information Science and Technology Nanjing China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Key Laboratory of Meteorological Disasters Ministry of Education Joint International Research Laboratory of Climate and Environment Change Nanjing University of Information Science and Technology Nanjing China School of Earth Sciences Yunnan University Kunming China National Climate Center China Meteorological Administration Beijing China State Key Laboratory of Earth Surface Processes and Resource Ecology Faculty of Geographical Science Beijing Normal University Beijing China Zhuhai China

During summer 2020, Southern China experienced an extremely dry and hot summer, which was identified as one of the top ten domestic weather and climate extreme events in 2020 by China Meteorological Administration. Summer mean precipitation, surface air temperature (TAS), and number of hot days (NHD) were about 25% dryer, 1.5℃ warmer, and 11 days larger than the 1981–2010 normal. These are the 4th largest precipitation deficit, the highest TAS, and the 2nd highest NHD in the 1961–2020 record. The large-scale circulation anomalies over the West Pacific increased the likelihood of these extremely event. Anthropogenic influences on this event were investigated using 525-member ensembles of the atmosphere-only HadGEM3-GA6 model and the multi-model ensembles from the Coupled Model Intercomparison Project Phase 6 (CMIP6). Anthropogenic forcings doubled (increased by 11%) the probability of precipitation deficits, and increased occurrence more than [[EQUATION]] times for both TAS anomaly (1.25[[EQUATION]] probability higher) and NHD anomaly (300% probability higher) in HadGEM-GA6 (CMIP6). That means that the 2020-like TAS and NHD anomalies would not occur without anthropogenic forcings, and there is weak evidence that human influences decrease rainfall over Southern China. However, the precipitation deficit increased the likelihood of exceeding the observed thresholds for both TAS and NHD by about 17 (4) and 9 (11) times in HadGEM3-GA6 (CMIP6), respectively. Under SSP2-4.5 and SSP5-8.5 scenarios in the future, 2020-like hot but wet extreme events increase in magnitude and frequency, while the frequency of dry events declines. © 2024, The Authors. All rights reserved.

关键词： Climate models

来源：评论

学校读者我要写书评

暂无评论

Preliminary analysis of echolocation signals produced by fleeing Irrawaddy dolphins(Orcaella brevirostris)

引用

Acta Oceanologica Sinica 2019年第1期38卷 85-89页

作者： Ying Jiang Xuelei Zhang Zhiguo Yang Saifullah Arifin Jaaman Qinzeng Xu Azmi Marzuki Muda Hairul Masrini Muhamad First Institute of Oceanography Ministry of Natural Resources Laboratory for Regional Oceanography and Numerical Modeling Pilot National Laboratory for Marine Science and Technology (Qingdao) Laboratory for Marine Ecology and Environmental Science Pilot National Laboratory for Marine Science and Technology (Qingdao) China National Deep Sea Center Ministry of Natural Resources Institute of Oceanography & Environment University Malaysia Terengganu Key Laboratory of Underwater Acoustics and Marine Information Technology Department of Applied Marine Physics & Engineering College of Ocean and Earth Xiamen University

In this study, echolocation signals were recorded from a wild Irrawaddy dolphin(Orcaella brevirostris) in shallow water in the Bay of Brunei. During sound recording, a small fishing boat engine startled a nearby Irrawaddy dolphin and began chasing it on two occasions. Variations in the acoustic parameters were detected. When the Irrawaddy dolphin was startled and chased, the sound pressure level, number of click trains per minute, pulse number, and average inter-pulse interval(PI) per click train were all affected. The PI increased and exhibited a slight downward trend during the chase. The increase in PI indicated an increase in the inspection distance as the dolphin escaped. Thus, Irrawaddy dolphins may adapt their echolocation signals to stand out from ambient noise in the wild and to improve their search efforts in potentially risky situations. Appropriate management of the burst noise around the dolphins is important.

关键词： click train echolocation signal Irrawaddy dolphin signal change

来源：评论

学校读者我要写书评

暂无评论

Joint mass-and-energy test of the equivalence principle at the 10−10 level using atoms with specified mass and internal energy

引用

Physical Review A 2021年第2期104卷 022822-022822页

作者： Lin Zhou Chuan He Si-Tong Yan Xi Chen Dong-Feng Gao Wei-Tao Duan Yu-Hang Ji Run-Dong Xu Biao Tang Chao Zhou Sachin Barthwal Qi Wang Zhuo Hou Zong-Yuan Xiong Yuan-Zhong Zhang Min Liu Wei-Tou Ni Jin Wang Ming-Sheng Zhan State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences-Wuhan National Laboratory for Optoelectronics Wuhan 430071 China School of Physical Sciences University of Chinese Academy of Sciences Beijing 100049 China Light and Matter Physics Raman Research Institute Sadashivanagar Bangalore 560080 India Institute of Theoretical Physics Chinese Academy of Sciences Beijing 100190 China

We use rubidium atoms with specified mass and internal energy to carry out a joint mass-energy test of the equivalence principle (EP). We improve the four-wave double-diffraction Raman transition method (4WDR) we proposed before to select atoms with a certain mass and angular momentum state, and form a dual-species atom interferometer. By using the extended 4WDR to Rb85 and Rb87 atoms with different angular momenta, we measure their differential gravitational acceleration, and we determine the value of the Eötvös parameter, η, which measures the strength of the violation of EP. The Eötvös parameters of the four paired combinations Rb85|F=2〉−Rb87|F=1〉, Rb85|F=2〉−Rb87|F=2〉, Rb85|F=3〉−Rb87|F=1〉, and Rb85|F=3〉−Rb87|F=2〉 were measured to be η1=(1.5±3.2)×10−10, η2=(−0.6±3.7)×10−10, η3=(−2.5±4.1)×10−10, and η4=(−2.7±3.6)×10−10, respectively. The violation parameter of mass is constrained to η0=(−0.8±1.4)×10−10, and that of internal energy to ηE=(0.0±0.4)×10−10 per reduced energy ratio a (a=hν0/mi85c2, and ν0=1 GHz). This work opens a door for joint tests of two attributes beyond the traditional pure mass or energy tests of EP with quantum systems.

关键词： Atom interferometry Coherent control Atoms Mach-Zehnder atom interferometry

来源：评论

学校读者我要写书评

暂无评论

Adaptive feed-forward control for seeker based on the disturbance observer

Adaptive feed-forward control for seeker based on the distur...

引用

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

作者： Xin Liu Zhenhong Niu Yi Shu Lian Xue Mingchao Zhu National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences

In order to improve the tracking and stabilization performance, a control method combining disturbance observer and adaptive feed-forward control using parameterization is proposed for seeker stabilized platforms. The system identification algorithm is used to identify dynamic model of the true plant. Then the discrete-time disturbance observer is designed. The feedback loop controller is designed using pole-placement techniques. The recursive least square (RLS) adaptive filter is used to build the inverse model of the feedback control loop and in this way, the feed-forward control is constructed. The adaptive filter and the feedback loop constitute a control scheme with two degrees-of-freedom (DOF). Tracking experiments conducted on velocity command inputs verify the validity of the adaptive feed-forward controller. Experimental results show that this method responses quickly to commands. For a sinusoidal signal at the frequency of 30Hz, the adaptive feed-forward controller can obtain an amplitude response without attenuation and the phase lag is reduced to 11° in contrast with the feedback control whose phase lag is 60°. This method significantly improves the transient performance and is superior to the feedback control alone.

关键词： Adaptive filters Feedback control Disturbance observers Feedforward systems Low pass filters Tracking loops Stability analysis

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：