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Rescheduling of observing spacecraft using fuzzy neural network and ant colony algorithm

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Chinese Journal of Aeronautics 2014年第3期27卷 678-687页

作者： Li Yuqing Wang Rixin Xu Minqiang Deep space Exploration Research Center Harbin Institute of Technology

This paper aims at rescheduling of observing spacecraft imaging plans under uncertainties. Firstly, uncertainties in spacecraft observation scheduling are analyzed. Then, considering the uncertainties with fuzzy features, this paper proposes a fuzzy neural network and a hybrid rescheduling policy to deal with them. It then establishes a mathematical model and manages to solve the rescheduling problem by proposing an ant colony algorithm, which introduces an adaptive control mechanism and takes advantage of the information in an existing schedule. Finally, the above method is applied to solve the rescheduling problem of a certain type of earth-observing satellite. The computation of the example shows that the approach is feasible and effective in dealing with uncertainties in spacecraft observation scheduling. The approach designed here can be useful in solving the problem that the original schedule is contaminated by disturbances.

关键词： Ant colony algorithm Planning and scheduling Rescheduling spacecraft observing Uncertainty

Modeling the frictional torque of a dry-lubricated tapered roller bearing considering the roller skewing

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Friction 2019年第6期7卷 551-563页

作者： Chi ZHANG Le GU Yuze MAO Liqin WANG Research Lab of space & Aerospace Tribology Harbin Institute of Technology

In this paper, an equation for the calculation of the frictional torque of a dry-lubricated tapered roller bearing(TRB) is provided in which the effect of the roller skewing is emphasized. Calculations were performed to investigate the effect of the roller skewing on the torque of dry-lubricated TRB for two representative preload methods, that is, axial force preload and axial displacement preload. The results show that a proper roller skewing angle under axial force preload benefits the reduction of the TRB torque. However, the roller skewing angle should not exceed a certain critical value;otherwise, it will cause a steep rise in the TRB torque. Finally, the critical value of the roller skewing angle as a function of the friction coefficient and cage pocket clearance is presented. The developed torque model provides a tool for the internal design and torque optimization of dry-lubricated TRBs.

关键词： tapered roller bearing frictional torque roller skewing dry lubrication

Disturbance observer-based robust guidance for Mars atmospheric entry with input saturation

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Chinese Journal of Aeronautics 2015年第3期28卷 845-852页

作者： Zheng Yiyu Cui Hutao Deep space Exploration Research Center Harbin Institute of Technology

Abstract With low-lifting capability taken into account, a robust guidance law for Mars entry vehicles with low lift-l：o-drag ratios, such as Mars Science Laboratory （MSL）, is presented. Consider the nonlinear term in the drag dynamic equation and bounded disturbances as a lumped disturbance, and design a linear disturbance observer （DOB） to estimate it. With the consideration of the control input saturation, an innovative sliding surface and a virtual system are introduced to design the guidance law. Analyses of disturbance observer performance and Lyapunov-based transient performance are also presented. It is shown explicit choices of design parameters. Simulation guidance law. that the drag tracking error can be adjustable by results confirm the effectiveness of the proposed

关键词： Disturbance observer Guidance Input saturation Mars atmospheric entry Robustness

Fault detection of flywheel system based on clustering and principal component analysis

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Chinese Journal of Aeronautics 2015年第6期28卷 1676-1688页

作者： Wang Rixin Gong Xuebing Xu Minqiang Li Yuqing Deep space Exploration Research Center Harbin Institute of Technology

Considering the nonlinear, multifunctional properties of double-flywheel with closed- loop control, a two-step method including clustering and principal component analysis is proposed to detect the two faults in the multifunctional flywheels. At the first step of the proposed algorithm, clustering is taken as feature recognition to check the instructions of ＂integrated power and attitude control＂ system, such as attitude control, energy storage or energy discharge. These commands will ask the flywheel system to work in different operation modes. Therefore, the relationship of parameters in different operations can define the cluster structure of training data. Ordering points to identify the clustering structure （OPTICS） can automatically identify these clusters by the reachability-plot. K-means algorithm can divide the training data into the corresponding operations according to the teachability-plot. Finally, the last step of proposed model is used to define the rela- tionship of parameters in each operation through the principal component analysis （PCA） method. Compared with the PCA model, the proposed approach is capable of identifying the new clusters and learning the new behavior of incoming data. The simulation results show that it can effectively detect the faults in the multifunctional flywheels system.

关键词： Attitude control Cluster analysis Energy storage Fault detection Flywheels

Magnetotail dipolarization fronts and particle acceleration:A review

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Science China Earth Sciences 2020年第2期63卷 235-256页

作者： Huishan FU Elena EGRIGORENKO Christine GABRIELSE Chengming LIU San LU KJHWANG Xuzhi ZHOU Zhe WANG Fang CHEN School of space and Environment Beihang UniversityBeijing 102206China space Research institute of RAS MoscowRussia Earth Planetaryand Space Sciences DepartmentUniversity of CaliforniaLos AngelesUSA Southwest Research institute San AntonioUSA institute of space Physics and Applied Technology Peking UniversityBeijing 100871China

In this paper, the particle acceleration processes around magnetotail dipolarization fronts(DFs) were reviewed. We summarize the spacecraft observations(including Cluster, THEMIS, MMS) and numerical simulations(including MHD, testparticle, hybrid, LSK, PIC) of these processes. Specifically, we(1) introduce the properties of DFs at MHD scale, ion scale, and electron scale,(2) review the properties of suprathermal electrons with particular focus on the pitch-angle distributions,(3)define the particle-acceleration process and distinguish it from the particle-heating process,(4) identify the particle-acceleration process from spacecraft measurements of energy fluxes, and(5) quantify the acceleration efficiency and compare it with other processes in the magnetosphere(e.g., magnetic reconnection and radiation-belt acceleration processes). We focus on both the acceleration of electrons and ions(including light ions and heavy ions). Regarding electron acceleration, we introduce Fermi,betatron, and non-adiabatic acceleration mechanisms;regarding ion acceleration, we present Fermi, betatron, reflection, resonance, and non-adiabatic acceleration mechanisms. We also discuss the unsolved problems and open questions relevant to this topic, and suggest directions for future studies.

关键词： Dipolarization front Electron acceleration Ion acceleration Magnetic reconnection Review Reconnection front

Development and prospects of the fire space monitoring system in Kazakhstan

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Frontiers of Earth Science 2012年第3期6卷 276-282页

作者： Lev SPIVAK Oleg ARKHIPKIN Gulshat SAGATDINOVA space Research institute National Center of Space Research and Technology Shevchenko Almaty 050010 Kazakhstan

This article provides a brief description of the fire space monitoring system in Kazakhstan, including the GIS-technology incorporated in its structure. The system performs operative space monitoring of fire areas and burnt areas, mapping of large fire areas, analysis of seasonal and long-term dynamics of burnt areas, and estimation of fire risk zones. Examples of output information obtained from space monitoring of fires are given. Possible directions of development of fire space monitoring in Kazakhstan are specified.

关键词： space images remote sensing fire space monitoring fire areas burnt areas operating mapping,zones of high fire risk

Analysis of interval constants in calendars affiliated with the Shoushili

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Research in Astronomy and Astrophysics 2014年第4期14卷 485-496页

作者： Byeong-Hee Mihn Ki-Won Lee Young Sook Ahn Advanced Astronomy and space Science Division Korea Astronomy and Space Science Institute Department of Astronomy and space Science Chungbuk National University institute of Liberal Education Catholic University of Daegu

We study interval constants that are related to motions of the Sun and Moon, i.e., the Qi, Intercalation, Revolution and Crossing interval, in calendars affiliated with the Shoushi calendar （Shoushili）, such as Datongli and Chiljeongsannaepyeon. It is known that these interval constants were newly introduced in the Shoushili calendar and revised afterward, except for the Qi interval constant, and the revised values were adopted in later calendars affiliated with the Shoushili. We first investigate the accu- racy of these interval constants and then the accuracy of calendars affiliated with the Shoushili in terms of these constants by comparing times for the new moon and the maximum solar eclipse calculated by each calendar with modem methods of calcula- tion. During our study, we found that the Qi and Intercalation interval constants used in the early Shoushili were well determined, whereas the Revolution and Crossing interval constants were relatively poorly measured. We also found that the interval constants used by the early Shoushili were better than those of the later one, and hence better than those of Datongli and Chiljeongsannaepyeon. On the other hand, we found that the early Shoushili is, in general, a worse calendar than Datongli for use in China but a better one than Chiljeongsannaepyeon for use in Korea in terms of times for the new moon and when a solar eclipse occurs, at least for the period 1281 - 1644. Finally, we verified that the times for sunrise and sunset in the Shoushili-Li-Cheng and Mingshi are those at Beijing and Nanjing, respectively.

关键词： history and philosophy of astronomy: general -- celestial mechanics --ephemerides

Application of two special orbits in the orbit determination of lunar satellites

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Research in Astronomy and Astrophysics 2014年第10期14卷 1307-1328页

作者： Peng Liu Xi-Yun Hou Jing-Shi Tang Lin Liu School of Astronomy and space Science Nanjing University institute of space Environment and Astrodynamics Nanjing University

Using inter-satellite range data, the combined autonomous orbit determina- tion problem of a lunar satellite and a probe on some special orbits is studied in this paper. The problem is firstly studied in the circular restricted three-body problem, and then generalized to the real force model of the Earth-Moon system. Two kinds of spe- cial orbits are discussed： collinear libration point orbits and distant retrograde orbits. Studies show that the orbit determination accuracy in both cases can reach that of the observations. Some important properties of the system are carefully studied. These findings should be useful in the future engineering implementation of this conceptual study.

关键词： celestial mechanics -- space vehicles -- Moon -- methods numerical

Double lunar swing-by orbits revisited

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Science China(Physics,Mechanics & Astronomy) 2014年第4期57卷 784-790页

作者： HOU XiYun LIU Lin School of Astronomy and space Science Nanjing University institute of space Environment and Astrodynamics Nanjing University

The double lunar swing-by orbits are a special kind of orbits in the Earth-Moon *** orbits repeatedly pass through the vicinity of the Moon and change their shapes due to the Moon’s *** the synodic frame of the circular restricted three-body problem consisting of the Earth and the Moon,these orbits are periodic,with two close approaches to the Moon in every orbit *** this paper,these orbits are *** is found that these orbits belong to the symmetric horseshoe periodic families which bifurcate from the planar Lyapunov family around the collinear libration point ***,the double lunar swing-by orbits have k=i+j loops,where i is the number of the inner loops and j is the number of outer *** genealogy of these orbits with different i and j is studied in this *** is,how these double lunar swing-by orbits are organized in the symmetric horseshoe periodic families is *** addition,the 2n lunar swing-by orbits(n≥2)with 2n close approaches to the Moon in one orbit period are also studied.

关键词： double lunar swing-by orbit restricted three-body problem periodic orbit