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arXiv 2024年

作者： Nakariakov, Valery M. Zhong, Sihui Kolotkov, Dmitrii Y. Meadowcroft, Rebecca L. Zhong, Yu Yuan, Ding Centre for Fusion Space & Astrophysics Department of Physics University of Warwick CoventryCV4 7AL United Kingdom " Ventspils University of Applied Sciences VentspilsLV-3601 Latvia Shenzhen Key Laboratory of Numerical Prediction for Space Storm Harbin Institute of Technology Shenzhen Guangdong518055 China Key Laboratory of Solar Activity and Space Weather National Space Science Center Chinese Academy of Sciences Beijing100190 China

Macroscopic wave and oscillatory phenomena ubiquitously detected in the plasma of the corona of the Sun are interpreted in terms of magnetohydrodynamic theory. Fast and slow magnetoacoustic waves are clearly distinguished in observations. Properties of coronal magnetohydrodynamic waves are determined by local parameters of the plasma, including the field-aligned filamentation typical for the corona. It makes coronal magnetohydrodynamic waves reliable probes of the coronal plasma structures by the method of magnetohydrodynamic seismology. For example, propagating slow waves indicate the local direction of the guiding magnetic field. Standing, sloshing and propagating slow waves can be used for probing the coronal heating function and the polytropic index. Kink oscillations of coronal plasma loops provide us with the estimations of the absolute value of the magnetic field in oscillating plasma loops. This tutorial introduces several techniques of magnetohydrodynamic seismology of solar coronal plasmas. It includes the description of practical steps in the data acquisition, pre-processing, and processing using the open-access data of the Atmospheric Imaging Assembly on the Solar Dynamics Observatory spacecraft, and elaborated data analysis techniques of motion magnification and Bayesian statistics. © 2024, CC BY-NC-ND.

关键词： Seismology

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Universality of the Dynamic Characteristic Relationship of Electron Correlation in the Two-Photon Double Ionization Process of a Helium-Like System

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Chinese physics Letters 2020年第11期37卷 27-32页

作者： Fei Li Yu-Jun Yang Jing Chen Xiao-Jun Liu Zhi-Yi Wei Bing-Bing Wang Laboratory of Optical Physics Beijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of SciencesBeijing 100190China Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China Institute of Applied Physics and Computational Mathematics Beijing 100088China HEDPS Center for Applied Physics and TechnologyPeking UniversityBeijing 100084China State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and MathematicsInnovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China

Universality of the dynamic characteristic relationship between the characteristic time tc and the two-electron Coulomb interaction energy V12 of the ground state in the two-photon double ionization process is investigated via changing the parameters of the two-electron atomic system and the corresponding laser *** numerical results show that the product tcV12 keeps constant around 4.1 in the cases of changing the nucleus charge,the electron charge,the electron mass,and changing simultaneously the nucleus charge and the electron *** results demonstrate that the dynamic characteristic relationship in the two-photon double ionization process is *** work sheds more light on the dynamic characteristic relationship in ultrafast processes and may find its application in measurements of attosecond pulses.

关键词： conditions. charge characteristic

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Adaptive feed-forward control for seeker based on the disturbance observer 4

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

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4th IEEE Advanced Information technology, Electronic and Automation Control Conference, IAEAC 2019

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

ISBN: (纸本)9781728119076

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. © 2019 IEEE.

关键词： Adaptive filters

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Four-Fold Composite Structures and Triple Coherent Interfaces Endow Exceptional Mechanical Properties of an Fecrnialti High-Entropy Alloy

SSRN

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SSRN 2024年

作者： Wen, Donghui Jiang, Beibei Gao, Mengqi Huang, Zhaowen Kong, Fengyu Wang, Anding Wang, Qing Wang, Biao Liu, Chain-Tsuan Research Institute of Interdisciplinary Science School of Materials Science and Engineering Dongguan University of Technology Dongguan523808 China Analysis and Test Center Guangdong University of Technology Guangzhou510006 China Xinjiang Key Laboratory of Solid State Physics and Devices School of Physical Science and Technology Xinjiang University Ürümqi830046 China Hong Kong Institute for Advanced Study Mechanical Behavior Division Shenyang National Laboratory for Materials Science City University of Hong Kong Hong Kong School of Materials Science and Engineering Dalian University of Technology Dalian116024 China Department of Materials Science and Engineering China Sino-French Institute of Nuclear Engineering and Technology China

Introducing additional phases and constructing composite structures in BCC-based high-entropy alloys (HEAs) have recently been a hot spot for synergistically enhancing the strength and ductility at room and elevated temperatures. Here, we report a novel cost-efficiency (FeCrNi)85(AlTi)15 HEA that composed of four-fold composite structures with triple BCC/L21, L21/BCC and FCC/L12 coherent interfaces. The rationally introduction of ductile FCC phase in brittle BCC and L21 phases endows this composite alloy with an exceptional compressive plasticity of 37% at room-temperature. The well-controlled L21, BCC and L12 nano-particles coherently precipitate in BCC, L21 and FCC matrix phases, respectively, resulting in the super-high strength of 1850 MPa, outperforming other B2/L21-strengthened BCC HEAs. The triple coherent interfaces stabilize the composite microstructures and lead to the excellent yield strength at elevated temperatures (850 MPa at 700 °C, 395 MPa at 800 °C and 190 MPa at 900 °C). It is found that the FCC/L12 and L21/BCC composite phases can exhibit a high thermal stability even at 900 °C, which can partially compensate the strength decline from BCC/L21 phase dynamic recrystallization. These results obtain a new strategy for overcoming the drawback of inadequate deformability in BCC-based alloys and developing new composite materials for high-temperature applications. © 2024, The Authors. All rights reserved.

关键词： Precipitation (chemical)

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Impact analysis of CFAR detection for false targets generated by the phase-switched screen

Impact analysis of CFAR detection for false targets generate...

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2019 IEEE International Conference on Signal, Information and Data Processing, ICSIDP 2019

作者： Zheng, Ran Chen, Yuan S Zhang, Yu X Guo, Lei Bai, Liang J Zhang, Ping L Zhang, Ran National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing Institute of Space Long March Vehicle Beijing China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing Institute of Space Long March Vehicle No. 1 Nanda Hongmen Road of Fengtai District Beijing China

ISBN: (纸本)9781728123455

The phase-switched screen (PSS) has been proved effective in the application of shielding a target or deceiving the radar system when the modulation frequency of it is set greater or smaller than the signal bandwidth. This paper analyses impacts of false targets generated by PSS (PSS-decoys) echoes on radar constant false alarm rate detection. The generation principle of PSS-decoys and the key factors that influence the signatures of PSS-decoys are introduced briefly at first. On base of it, the detection cost caused by the false alarm and false dismissal in a search period of radar is chosen as the criteria of detection performance. The detection costs of CA-CFAR, OS-CFAR, CMLD-CFAR detectors under multiple decoys jamming environment are analysed. Specially, we investigate the influence of the PSS key factors on detection costs from the perspective of simulation. The results show that detection costs will increase remarkably due to false targets existing and it is sensitive to the switching frequency, and the relationship to the duty ratio is tightly relevant to SNR. Among three detectors, the detection costs of CMLD-CFAR detector are higher than that of adopting CA-CFAR and that of adopting OS-CFAR. © 2019 IEEE.

关键词： Signal detection

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

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

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2019 IEEE International Conference on Signal, Information and Data Processing, ICSIDP 2019

作者： Qi, Sun-Rui Yuan, Chen-Shun Liang, Bai-Jin 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 Beijing100076 China

ISBN: (纸本)9781728123455

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. © 2019 IEEE.

关键词： Time difference of arrival

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Generative Decoding for Quantum Error-correcting Codes

arXiv

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arXiv 2025年

作者： Cao, Hanyan Pan, Feng Feng, Dongyang Wang, Yijia Zhang, Pan CAS Key Laboratory for Theoretical Physics Institute of Theoretical Physics Chinese Academy of Sciences Beijing100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing100049 China Centre for Quantum Technologies National University of Singapore 117543 Singapore Science Mathematics and Technology Cluster Singapore University of Technology and Design 8 Somapah Road 487372 Singapore School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced Study UCAS Hangzhou310024 China

Efficient and accurate decoding of quantum error-correcting codes is essential for fault-tolerant quantum computation, however, it is challenging due to the degeneracy of errors, the complex code topology, and the large space for logical operators in high-rate codes. In this work, we propose a decoding algorithm utilizing generative modeling in machine learning. We employ autoregressive neural networks to learn the joint probability of logical operators and syndromes in an unsupervised manner, eliminating the need for labeled training data. The learned model can approximately perform maximum likelihood decoding by directly generating the most likely logical operators for k logical qubits with O(2k) computational complexity. Thus, it is particularly efficient for decoding high-rate codes with many logical qubits. The proposed approach is general and applies to a wide spectrum of quantum error-correcting codes including surface codes and quantum low-density parity-check codes (qLDPC), under noise models ranging from code capacity noise to circuit level noise. We conducted extensive numerical experiments to demonstrate that our approach achieves significantly higher decoding accuracy compared to the minimum weight perfect matching and belief propagation with ordered statistics on the surface codes and high-rate quantum low-density parity-check codes. Our approach highlights generative artificial intelligence as a potential solution for the real-time decoding of realistic and high-rate quantum error correction codes. © 2025, CC BY.

关键词： Qubits

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The Island Rule with lateral and bottom friction

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Acta Oceanologica Sinica 2019年第4期38卷 146-153页

作者： Yanzhao Yang Zexun Wei Guanlin Wang Zhan Lian Liwei Wang College of Meteorology and Oceanography National University of Defense Technology College of Mathematical Science and Physics Qingdao University of Science and Technology Key Laboratory of Marine Science and Numerical Modeling First Institute of OceanographyMinistry of Natural Resources Laboratory for Regional Oceanography and Numerical Modeling Pilot National Laboratory for Marine Science and Technology (Qingdao)

The Island Rule, derived from the Sverdrup theory, is widely used to estimate and analyze water transport through a strait. Previous studies presented single-or multi-island rules with either lateral or bottom friction. In this paper,an analytical model of wind-driven circulation is assumed based on linear dynamics. Considering both lateral and bottom friction, the analytic solutions of the transport streamfunction around the islands are derived and the volume transport through the channel is presented. The results are similar to those of Wajsowicz, but the frictional constants represent different values. The analytic solution shows that the relationship between the lateral frictional and bottom frictional dissipation is complex in terms of the frictional constants. To understand the interaction between the two friction types, lateral and bottom friction values were randomly chosen on a barotropic beta plane. The result shows an approximately linear relationship between the lateral and bottom friction in consisting of the combined frictional constants. We studied the effect of the channel width on the transport through the channel. The results show that the friction enhances the flow under some widths, which is similar to the flow behavior when only the lateral friction is considered. We also compared the transport through the channel at different depths and founded that the deeper the water, the smaller the transport reduction ratio when the horizontal eddy viscosity coefficient and the bottom drag coefficient remained constants. To further present the combined role of lateral frictional and bottom frictional dissipation, we compared our model with the model of Wajsowicz for two islands, where only the lateral or bottom friction were considered, with different channel widths. The results showed that the effect of the lateral friction is greater than the bottom friction when the channel is narrow, especially in the Munk boundary layer thickness. When the channel is

关键词： Island Rule lateral friction bottom friction transport streamfunction

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Design of Non-uniform Flexible Meta-surface for Antenna Beam-steering

Design of Non-uniform Flexible Meta-surface for Antenna Beam...

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IEEE International Conference on Electronic Information and Communication technology (ICEICT)

作者： Yuwei Qiu Zhiye Jiang Pei Zheng School of Electronic Information Northwestern Polytechnical University Xi'an China National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics Beijing China

ISBN: (数字)9781728190457

ISBN: (纸本)9781728190464

Design of non-uniform flexible meta-surface for antenna beam-steering is presented in this paper. By properly tuning the dimensions of quasi-I-shaped unit cells on meta-surface, we propose a bi-layer meta-surface that can achieve beam deflection of up to 34°. Horn antenna is adopted as the feed antenna to illuminate the meta-surface which is printed on flexible plastic sheet. The meta-surface is fixed on the outside surface of horn antenna with an electric motor, making it possible to slide relative to the aperture of feed antenna. The horn antenna together with the meta-surface will work like a projector when operating, the main-beam of the horn antenna can be steered when different frames of the meta-surface cover the horn aperture and the steering range is ±34°. Radiation reconfigurable is thus achieved through a simple structure. Prototype will be fabricated in the following research.

关键词： Horn antennas Prototypes Antenna feeds Aperture antennas Information and communication technology Plastics Tuning

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A Physical Layer key Generation method with Reliable Negotiation

A Physical Layer Key Generation method with Reliable Negotia...

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2019 IEEE International Conference on Signal, Information and Data Processing, ICSIDP 2019

作者： Wang, Yuchen Wu, Xuanli Xu, Zhicong Wu, Wei Li, Hu Zhang, Ran School of Electronics and Information Engineering Harbin Institude of Technology Harbin China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

ISBN: (纸本)9781728123455

There is a risk of information leakage in the process of wireless communication. The introduction of key generation in the physical layer can effectively improve the security of wireless communication. This paper proposes a new physical layer key generation method in the TDD (time division duplex) communication system. Assume that the uplink and downlink channels are reciprocal. Through LDPC (Low Density Parity Check)channel coding and negotiation algorithm, the inconsistency rate of key generation between Alice and Bob is reduced. Simulation and analysis results show that the method improves the key generation rate and reduces the key inconsistency rate. © 2019 IEEE.

关键词： Hash functions

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