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China Communications 2018年第3期15卷 128-136页

作者： Yujie Lin Xiangyuan Bu Shuai Wang Yuan Chai Jianping An School of Information and Electronics Beijing Institute of Technology institute of telecommunication satellite China Academy of Space Technology

For spaceborne multi-beam antennas(MBAs), time division multiplexed switching(TDMS) based calibration receiver can reduce implementation costs effectively and is very suitable for large-scale applications. However, in practice, random phase noise imposed by noisy local oscillators can cause significant performance degradation in TDMS-based calibration systems. Characterization of phase noise effects is therefore crucial for practical applications. In this paper, we analyze the impact of phase noise on the calibration performance for a MBA system. Specifically, we derive the relationship between the probability of correct amplitude/phase estimation and various practical factors involving the signal-to-noise ratio(SNR), the standard deviation of phase noise, the given tolerance region, and the length of the spreading code. The results provide high efficiency for evaluating the calibration performance of the MBAs based on TDMS, especially for precisely anticipating the impact of phase noise. Finally, the accuracy of the derived results is assessed by simulations in different scenarios.

关键词： multi-beam antenna calibration phase noise time division multiplexed switching

Study on fluid-structure interaction in liquid oxygen feeding pipe systems using finite volume method

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Acta Mechanica Sinica 2011年第5期27卷 706-712页

作者： Xin Wei Bing Sun institute of telecommunication satellite China Academy of Space Technology100194 Beijing China School of Astronautics Beihang University 100191 Beijing China

The fluid-structure interaction may occur in space launch vehicles,which would lead to bad performance of vehicles,damage equipments on vehicles,or even affect astronauts＇ *** this paper,analysis on dynamic behavior of liquid oxygen （LOX） feeding pipe system in a large scale launch vehicle is performed,with the effect of fluid-structure interaction （FSI） taken into *** pipe system is simplified as a planar FSI model with Poisson coupling and junction *** tests on pipes between the tank and the pump are solved by the finite volume *** show that restrictions weaken the interaction between axial and lateral *** reasonable results regarding frequencies and modes indicate that the FSI affects substantially the dynamic analysis,and thus highlight the usefulness of the proposed *** study would provide a reference to the pipe test,as well as facilitate further studies on oscillation suppression.

关键词： Fluid-structure interaction · Liquid oxygen · Finite volume method

Response of magnetic fields at geosynchronous orbit and on the ground to the sudden changes of IMF B_Z

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Science China(Technological Sciences) 2014年第2期57卷 360-367页

作者： DONG YiXuan CAO JinBin LIU WenLong ZHANG Lei LI LiuYuan Beijing institute of Spacecraft Environment Engineering Space Science institute School of Astronautics Beihang University institute of telecommunication satellite China Academy of Space Technology

The rapid change in the Earth’s magnetosphere caused by solar wind disturbances has been an important part of the solar wind-magnetosphere *** most of the previous studies focused on the perturbation of the Earth’s magnetic field caused by solar wind dynamic pressure *** this paper,we studied the response of geosynchronous magnetic field and the magnetic field to the rapid southward turning of interplanetary magnetic field during the interval 1350 1420 UT on 7May *** this event,BZ component of the interplanetary magnetic field decreased from 15 nT to 10 nT within 3 min(1403 1406 UT).The geosynchronous magnetic field measured by three geosynchronous satellites(GOES 10 12)first increased and then *** variations of magnetic field strength in the morning sector(9 10 LT)were much larger than those in the dawn sector(5 LT).Meanwhile,the H components of geomagnetic field on the ground have similar response features but exhibit latitude and LT dependent *** with H components,the D components do not have regular *** the solar wind dynamical pressure encounters small variations,the magnetic field both in space and on the ground does not display similar ***,the increase of geomagnetic field in the dawn sector is caused by the southward turning of IMF(interplanetary magnetic field)*** results will help to better understand the coupling process of geomagnetic filed and interplanetary magnetic field.

关键词： interplanetary magnetic field (IMF) solar wind geosynchronous orbit geomagnetic field

A Recursive DRL-Based Resource Allocation Method for Multibeam satellite Communication Systems

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Chinese Journal of Electronics 2024年第5期33卷 1286-1295页

作者： Haowei MENG Ning XIN Hao QIN Di ZHAO State Key Laboratory of Integrated Services Networks Xidian University China Academy of Space Technology Institute of Telecommunication Satellite

Optimization-based radio resource management(RRM) has shown significant performance gains on high-throughput satellites(HTSs). However, as the number of allocable on-board resources increases, traditional RRM is difficult to apply in real satellite systems due to its intense computational complexity. Deep reinforcement learning(DRL) is a promising solution for the resource allocation problem due to its model-free advantages. Nevertheless, the action space faced by DRL increases exponentially with the increase of communication scale, which leads to an excessive exploration cost of the algorithm. In this paper, we propose a recursive frequency resource allocation algorithm based on long-short term memory(LSTM) and proximal policy optimization(PPO), called PPO-RA-LOOP,where RA means resource allocation and LOOP means the algorithm outputs actions in a recursive manner. Specifically, the PPO algorithm uses LSTM network to recursively generate sub-actions about frequency resource allocation for each beam, which significantly cuts down the action space. In addition, the LSTM-based recursive architecture allows PPO to better allocate the next frequency resource by using the generated sub-actions information as a prior knowledge, which reduces the complexity of the neural network. The simulation results show that PPO-RA-LOOP achieved higher spectral efficiency and system satisfaction compared with other frequency allocation algorithms.

关键词： Knowledge engineering Spectral efficiency Simulation satellite broadcasting Neural networks Performance gain Resource management

Performance analysis of broadband satellite communication system based on OFDM/TDM

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The Journal of China Universities of Posts and telecommunications 2013年第3期20卷 37-42,77页

作者： TIAN Qing-hua ZHANG Qi TAO Ying LIU Nai-jin XIN Xiang-jun ZHANG Li-jia XU Da-xiong institute of Optical Communication and Optoelectronics Beijing University of Posts and Telecommunications School of Electronic Engineering Beijing University of Posts and Telecommunications institute of telecommunication satellite China Academy of Space Technology

Orthogonal frequency division multiplexing （OFDM） is attracting more attention for its capability of high speed transmission. However, the OFDM possesses an obvious shortage in its high ratio of the peak power to the average power （PAPR）, which has become the main issue holding it back to be applied to the broadband satellite communication system. OFDM combined with time division multiplexing （TDM）, dividing the subcarriers of OFDM into some blocks in time tune, can decrease the high PAPR of OFDM. Meanwhile, the advantages of OFDM can be preserved. In this paper, OFDM/TDM is applied to the broadband satellite communication system. This paper theoretically analyses OFDM/TDM system model as well as its restraining effect on PAPR, and proposes frequency domain multiplexing-pilot （FDM-Pilot） channel estimation algorithm. Simulation results show OFDM/TDM in broadband satellite communication system has approving performance and decreased the PAPR.

关键词： OFDM/TDM broadband satellite communication system PAPR channel estimation

Effect of curing condition on bonding quality of scarf-repaired composite laminates

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Chinese Journal of Aeronautics 2020年第8期33卷 2257-2267页

作者： Jie ZHANG Xiaoquan CHENG Jikui ZHANG Xin GUO Wenjun HUANG School of Aeronautic Science and Engineering Beihang UniversityBeijing 100083China institute of telecommunication satellite China Academy of Spacecraft TechnologyBeijing 100094China AVIC China Helicopter Research and Development institute Jingdezhen 333001China

Both single-face vacuum bag curing(SVC) and double-face vacuum bag curing(DVC)can be used in scarf repair of composite structures. But different curing conditions caused by the sealing state may affect the bonding quality of scarf-repaired structures. In this paper, the effect of curing condition on bonding quality of scarf-repaired laminates was experimentally investigated in terms of surface profiles, moisture absorption curves and section profiles. In order to further explore the moisture absorption mechanism, finite element model of the repaired laminates using DVC was established with moisture diffusion of both the adhesive and composite laminates considered. This model was verified by experimental results. Based on the model of DVC case, the model of SVC case was built by changing moisture absorption parameters of the adhesive. Results show that SVC reduces the bonding quality, mainly reflecting in more adhesive inner voids and patch-toparent dislocation. And SVC increases moisture absorption rate and moisture equilibrium content of the adhesive, and its effect on the former is far greater than that on the latter.

关键词： Bonding quality Curing condition Finite element model Moisture behavior Scarf-repaired composite laminate

Multi-band microwave photonic satellite repeater scheme employing intensity Mach-Zehnder modulators

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The Journal of China Universities of Posts and telecommunications 2017年第2期24卷 89-95页

作者： Yin Jie Dong Tao Zhang Bin Hao Yan Cao Guixing Cheng Zijing Xu Kun Zhou Yue Dai Jian Beijing institute of satellite Information Engineering State Key Laboratory of Space-Ground Integrated Information Technology Space Star Technology Company Limited institute of telecommunication satellite China Academy of Space Technology State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications

To solve the satellite repeater＇s flexible and wideband frequency conversion problem, we propose a novel microwave photonic repeater system, which can convert the upload signal＇s carrier to six different frequencies. The scheme employs one 20 GHz bandwidth dual-drive Mach-Zehnder modulator （MZM） and two 10 GHz bandwidth MZMs. The basic principle of this scheme is filtering out two optical sidebands after the optical carrier suppression （OCS） modulation and combining two sidebands modulated by the input radio frequency （RF） signal. This structure can realize simultaneous multi-band frequency conversion with only one frequency-fixed microwave source and prevent generating harmful interference sidebands by using two corresponding optical filters after optical modulation. In the simulation, one C-band signal of 6 GHz carrier can be successfully converted to 12 GHz （Ku-band）, 28 GHz, 34 GHz, 40 GHz, 46 GHz （Ka-band） and 52 GHz （V-band）, which can be an attractive method to realize multi-band microwave photonic satellite repeater. Alternatively, the scheme can be configured to generate multi-band local oscillators （LOs） for widely satellite onboard clock distribution when the input RF signal is replaced by the internal clock source.

关键词： fiber optics and optical communication radio frequency photonics microwave photonics

Survivability model of LEO satellite constellation based on GERT with limited backup resources

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Journal of Systems Engineering and Electronics 2024年第4期35卷 976-986页

作者： NIE Yuanyuan FANG Zhigeng LIU Sifeng GAO Su College of Economics and Management Nanjing University of Aeronautics and AstronauticsNanjing 211106China institute of telecommunication satellite China Academy of Space TechnologyBeijing 100094China

Survivability is used to evaluate the ability of the satellite to complete the mission after failure,while the duration of maintaining performance is often *** effective backup strategy can restore the constellation performance timely,and maintain good network communication performance in case of satellite *** the perspective of network utility,the low Earth orbit(LEO)satellite constellation survivable graphical eva-luation and review technology(GERT)network with backup satel-lites is constructed.A network utility transfer function algorithm based on moment generating function and Mason formula is proposed,the network survivability evaluation models of on-orbit backup strategy and ground backup strategy are *** survivable GERT model can deduce the expected mainte-nance time of LEO satellite constellation under different fault states and the network utility generated during the state mainte-nance *** case analysis shows that the proposed surviv-able GERT model can consider the satellite failure rate,backup satellite replacement rate,maneuver control replacement ability and life requirement,and effectively determine the optimal sur-vivable backup strategy for LEO satellite constellation with limi-ted resources according to the expected network utility.

关键词： survivability low Earth orbit(LEO)satellite constella-tion graphical evaluation and review technology(GERT) backup strategy

Robust H_∞ guaranteed cost satisfactory fault-tolerant control for discrete-time systems with quadratic D stabilizability

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Journal of Systems Engineering and Electronics 2010年第3期21卷 496-502页

作者： Xiaodong Han Jiangong Liu Dexiao Xie Dengfeng Zhang Zhiquan Wang institute of telecommunication satellite China Academy of Space Technology Beijing 100094 P. R. China School of Automation Nanjing University of Science and Technology Nanjing 210094 E R. China

The problem of robust H∞ guaranteed cost satisfactory fault-tolerant control with quadratic D stabilizability against actuator failures is investigated for a class of discrete-time systems with value-bounded uncertainties existing in both the state and control input *** on a more practical and general model of actuator continuous gain failures,taking the transient property,robust behaviour on H∞ performance and quadratic cost performance requirements into consideration,sufficient conditions for the existence of satisfactory fault-tolerant controller are given and the effective design steps with constraints of multiple performance indices are ***,the consistency of the regional pole index,H∞ norm-bound constraint and cost performance indices is set up for fault-tolerant control.A simulation example shows the effectiveness of the proposed method.

关键词： fault-tolerant control actuator failures consistency theory quadratic D stabilizability.