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67th International Astronautical Congress, IAC 2016

作者： Wu, Runhui Liu, Jiaqi Liu, Xin Ren, Aimin Zhang, Shengjun Meng, Gang National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematical China Academy of Launch Vehicle Technology No 1 Nan Da Hong Men Road Beijing China

A spacecraft entering the Earth's atmosphere is enveloped by a plasma layer or sheath due to shock heating of the surrounding air and ablation of the heat shield material, and the plasma sheath may strongly effect the communication between the vehicles and receiver systems. In order to obtain the influence of communication system which is produced by reentry plasmas, a mechanism of QPSK signals through reentry plasmas which surround vehicles travelling at hypersonic velocities is proposed in this paper, and the simulation model of the QPSK signals propagation in plasma sheath is described. Then the energy attenuation and phase variable of QPSK signals which are transmitted by reentry plasmas are computed. The analysis results are shown that the QPSK signals would be shielded thoroughly if the plasma frequency is bigger than carrier frequency, and when the QPSK signals can propagate in reentry plasmas, the bit error probability (BEP) of communication systems would be improved by reentry plasmas which are ability to absorb the signals energy and vary signals phase. The simulation and analysis technique can also be used to calculate many other communication models such as FSK and ASK. Copyright © 2016 by the International Astronautical Federation (IAF). All rights reserved.

关键词： Bit error rate

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Optimization of compound regularization parameters based on Stein's unbiased risk estimate

Optimization of compound regularization parameters based on ...

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IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Feng Xue Hanjie Pan Runhui Wu Xin Liu Jiaqi Liu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing 100076 China Audiovisual Communications Laboratory School of Computer and Communication Sciences Ecole Polytechnique Federale de Lausanne (EPFL) Switzerland

ISBN: (纸本)9781509041183

Recently, the type of compound regularizers has become a popular choice for signal reconstruction. The estimation quality is generally sensitive to the values of multiple regularization parameters. In this work, based on BDF algorithm, we develop a data-driven optimization scheme based on minimization of Stein's unbiased risk estimate (SURE) - statistically equivalent to mean squared error (MSE). We propose a recursive evaluation of SURE to monitor the MSE during BDF iteration;the optimal values of the multiple parameters are then identified by the minimum SURE. Monte-Carlo simulation is applied to compute SURE for large-scale data. We exemplify the proposed method with image deconvolution. numerical experiments show that the proposed method leads to highly accurate estimates of regularization parameters and nearly optimal restoration performance.

关键词： Stein's unbiased risk estimate (SURE) compound regularizers regularization parameter BDF algorithm signal deconvolution Risk estimation Mean square error BDF unbiasedness Signal reconstruction parameters compounds highly accurate

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SMALL spacecraft: Rules and frames should be built from space security aspect 68

SMALL spacecraft: Rules and frames should be built from spac...

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68th International Astronautical Congress: Unlocking Imagination, Fostering Innovation and Strengthening Security, IAC 2017

作者： Zhang, Shengjun Sun, Yuan Xue, Hui Qin, Lihua Liu, Jiaqi Liu, Xin Mu, Lei Wang, Weidong Wang, Mingliang Ai, Xia National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing PO Box 9200-76-6 Beijing100076 China Academy of Launch Vehicle Technology Beijing China Institute of Survival Technology and Effectiveness Evaluation of Flying Vehicle No. 109 Beiqing Road Haidian District Beijing100093 China Beijing Institute of system engineering No. 109 Beiqing Road Haidian District Beijing100101 China

ISBN: (纸本)9781510855373

It has entering an age of small aerospace. New topics have been booming, such small satellite and cubesat, launcher for the small ones and commercial space, which are noticed not only by commercial groups but by the governments. More and more activities are taking place about these small spacecraft, India delivered about 100 cubesat during a launch this year, a small satellite was ejected from Small Satellite Orbital Deployer on the International Space Station in 2016, Some cubesats and small satellite from academical groups from Europe and China and other countries have been launched during other activities. While small spacecraft is benefit for its lower weight, lower cost, short R&D duration, and useful for scientific research, earth observation, and circumstance surveillance, satellite repairing, etc., there are more and more risks with the high speed delivering of manmade objects in low orbits. And in addition, with the development of small launch vehicles, the launching itself maybe executed by anyone themselves in the future. So there should be some new rules and frames built for activities and use of space from the aspect of space security, and which is benefit for the sustainable use of lower orbit and space, and thus for our mankind. Copyright © 2017 by the International Astronautical Federation (IAF). All rights reserved.

关键词： Orbits

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Derivation of the thermal characteristics of mesoscale eddies

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Acta Oceanologica Sinica 2017年第3期36卷 8-13页

作者： CHEN Xuan PAN Jing ZHENG Chongwei ZHANG Xi HE Ming The 75839 Army People's Liberation Army Guangzhou 510510 China National Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Dalian Naval Academy People's Liberation Army Dalian 116018 China College of Meteorology and Oceanography People's Liberation Army University of Science and Technology Nanjing 211101 China College of Marine Life Science Ocean University of China Qingdao 266003 China

This study aims at explaining the relationship between thermodynamic characteristics and direction of rotation of mesoscale eddies（MEs）. The geometric characteristics of the MEs are under the following assumptions： the structure of the MEs is symmetrical, and changes of oceanic physical variables are close to linear features in the radial direction in the ME regions. Based on these assumptions, by using primitive equations without friction under a cylindrical coordinate system, the thermodynamic characteristics of the MEs are derived, showing that the conventional relationship of warm anticyclonic eddies with high sea surface height（SSH） and cold cyclonic eddies with low SSH is not consistent with the SSH and sea surface temperature（SST） observations of eddies. The results show that the symmetrical form is an ideal approximation for the geometric characteristics of MEs. In consideration of the above assumptions, there are advantages for derivation of the characteristics of the MEs under a cylindrical coordinate.

关键词： mesoscale eddies thermodynamic characteristics symmetry

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Simulations of dissolved oxygen concentration in CMIP5 Earth system models

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Acta Oceanologica Sinica 2016年第12期35卷 28-37页

作者： BAO Ying LI Yangchun The First Institute of Oceanography State Oceanic Administration Laboratory for Regional Oceanography and Numerical Modeling Qingdao National Laboratory for Marine Science and Technology State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of Science

The climatologies of dissolved oxygen concentration in the ocean simulated by nine Earth system models(ESMs) from the historical emission driven experiment of CMIP5(Phase 5 of the Climate Model Intercomparison Project) are quantitatively evaluated by comparing the simulated oxygen to the WOA09 observation based on common statistical metrics. At the sea surface, distribution of dissolved oxygen is well simulated by all nine ESMs due to well-simulated sea surface temperature(SST), with both globally-averaged error and root mean square error(RMSE) close to zero, and both correlation coefficients and normalized standard deviation close to 1. However, the model performance differs from each other at the intermediate depth and deep ocean where important water masses exist. At the depth of 500 to 1 000 m where the oxygen minimum zones(OMZs) exist, all ESMs show a maximum of globally-averaged error and RMSE, and a minimum of the spatial correlation coefficient. In the ocean interior, the reason for model biases is complicated, and both the meridional overturning circulation(MOC) and the particulate organic carbon flux contribute to the biases of dissolved oxygen distribution. Analysis results show the physical bias contributes more. Simulation bias of important water masses such as North Atlantic Deep Water(NADW), Antarctic Bottom Water(AABW) and North Pacific Intermediate Water(NPIW) indicated by distributions of MOCs greatly affects the distributions of oxygen in north Atlantic, Southern Ocean and north Pacific, *** the model simulations of oxygen differ greatly from each other in the ocean interior, the multi-model mean shows a better agreement with the observation.

关键词： dissolved oxygen CMIP5 Earth system model meridional overturning circulation particulate organic carbon flux

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Erratum to: Regional Meteorological Patterns for Heavy Pollution Events in Beijing

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气象学报（英文版） 2018年第3期32卷 516-516页

作者： Ting YOU Renguang WU Gang HUANG Guangzhou FAN College of Atmospheric Sciences Chengdu University of Information Technology Chengdu 610225 Center for Monsoon System Research Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 Center for Monsoon System Research Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 Laboratory for Regional Oceanography and Numerical Modeling Qingdao National Laboratory for Marine Science and Technology Qingdao 266237 Joint Center for Global Change Studies Beijing 100875 University of Chinese Academy of Sciences Beijing 100049 College of Atmospheric Sciences Chengdu University of Information Technology Chengdu 610225

This erratum is to report a figure error in You et al.(2017) entitled “Regional Meteorological Patterns forHeavy Pollution Events in Beijing.” In You et al. (2017),Fig. 3 and its caption should be replaced by the fi...

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Research on networking communication technology based on small spacecraft 67

Research on networking communication technology based on sma...

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67th International Astronautical Congress, IAC 2016

作者： Peng, Qin Yang, Cao Lu, Gao Zhiye, Jiang Jinliang, Bai National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics China Academy of Launch Vehicle Technology No. 1 Nan Da Hong Men Road Beijing China

Small spacecrafts have many advantages such as distribution area controllable, flexible, easy networking and co-optimal allocation of resources. The distributed collaborative networking technology can make several small spacecrafts to co-ordinate and work together as a whole. The technology has good prospects in the aerospace field and has obtained wide attention, for it can achieve communication transmission, space exploration, decision-making tasks and other functions. This paper proposes a collaborative networking solution based on small spacecraft, focusing on the research of key technologies such as networking method, communication protocols, synchronous communication and interference. This paper designed a collaborative network communication system solution, developed a prototype and verified the feasibility of the solution through simulation analysis and prototype testing. This paper also suggested the ideas and methods to improve future collaborative network communication system. Copyright © 2016 by the International Astronautical Federation (IAF). All rights reserved.

关键词： Spacecraft

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Optimal Selection of regularization parameter for ?1-based image restoration based on SURE

Optimal Selection of regularization parameter for ?1-based i...

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International Symposium on Optoelectronic technology and Application 2016(OTA 2016)——Conf.12 Infrared technology and Application

作者： Feng Xue Xin Liu Hongyan Liu Jiaqi Liu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics

In real applications of infrared imaging and remote sensing, the observed images are often blurry and noisy due to the limitations of acquisition system. This degradation is often mathematically formu

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A recursive predictive risk estimate for proximal algorithms

A recursive predictive risk estimate for proximal algorithms

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Feng Xue Runle Du Jiaqi Liu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

ISBN: (纸本)9781479999897

For accurate signal reconstruction, proximal gradient methods generally require proper selection of regularization parameter. In this paper, we develop two data-driven optimization schemes, based on minimization of unbiased predictive risk estimate (UPRE). First, we propose a recursive UPRE to estimate the prediction error during the proximal iterations, which can be used to optimize the regularization parameter. Second, for fast optimization, we parametrize each proximal iterate as a linear combination of few elementary functions (LET), and solve the linear weights by minimizing recursive UPRE. We further exemplify the proposed approaches with the basic iterative shrinkage/thresholding (IST) algorithms for ℓ 1 -minimization. numerical experiments show that iterating this process leads to higher reconstruction accuracy with remarkably faster computational speed than standard IST.

关键词： Jacobian matrices Prediction algorithms Convergence Gradient methods Signal processing algorithms Standards

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Quantifying local predictability of the Lorenz system using the nonlinear local Lyapunov exponent

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Atmospheric and Oceanic science Letters 2017年第5期10卷 372-378页

作者： HUAI Xiao-Wei LI Jian-Ping DING Rui-Qiang FENG Jie LIU De-Qiang State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric PhysicsChinese Academy of Sciences Beijing China College of Earth Science University of Chinese Academy of Sciences Beijing China College of Global Change and Earth System Science (GCESS) Beijing Normal University Beijing China Joint Center for Global Change Studies Beijing Normal University Beijing China College of Atmospheric Sciences Plateau Atmosphere and Environment Key Laboratory of Sichuan Province Chengdu University of Information Technology Chengdu China GIobal Systems Division Earth System Research Laboratory/Oceanic and Atmospheric Research/National Oceanic and Atmospheric Administration Boulder CO USA Fujian Meteorological Observatory Fuzhou China

The nonlinear local Lyapunov exponent（NLLE） can be used as a quantification of the local predictability limit of chaotic systems. In this study, the phase-spatial structure of the local predictability limit over the Lorenz-63 system is investigated. It is found that the inner and outer rims of each regime of the attractor have a high probability of a longer than average local predictability limit, while the center part is the opposite. However, the distribution of the local predictability limit is nonuniformly organized, with adjacent points sometimes showing quite distinct error *** source of local predictability is linked to the local dynamics, which is related to the region in the phase space and the duration on the current regime.

关键词： Nonlinear local Lyapunov exponent local predictability limit chaotic system Lorenz system

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