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DOA estimation for attitude determination on communication satellites

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Chinese Journal of Aeronautics 2014年第3期27卷 670-677页

作者： Yang Bin He Feng jin jin xiong Huagang Xu Guanghan School of Electronic and Information Engineering Beihang University School of Aerospace Tsinghua University

In order to determine an appropriate attitude of three-axis stabilized communication satellites, this paper describes a novel attitude determination method using direction of arrival （DOA） estimation of a ground signal source. It differs from optical measurement, magnetic field measurement, inertial measurement, and global positioning system （GPS） attitude determination. The proposed method is characterized by taking the ground signal source as the attitude reference and acquiring attitude information from DOA estimation. Firstly, an attitude measurement equation with DOA estimation is derived in detail. Then, the error of the measurement equation is analyzed. Finally, an attitude determination algorithm is presented using a dynamic model, the attitude measurement equation, and measurement errors. A developing low Earth orbit （LEO） satellite which tests mobile communication technology with smart antennas can be stabilized in three axes by corporately using a magnetometer, reaction wheels, and three-axis magnetorquer rods. Based on the communication satellite, simulation results demonstrate the effectiveness of the method. The method could be a backup of attitude determination to prevent a system failure on the satellite. Its precision depends on the number of snapshots and the input signal-to-noise ratio （SNR） with DOA estimation.

关键词： Attitude determination Communication satellite Direction of arrival (DOA) estimation Low Earth orbit (LEO) Smart antennas

An Adaptive 2D Planar Projection and Its Application in Geoscience Studies

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Journal of Earth Science 2015年第5期26卷 724-728页

作者： Yong Zheng Bikai jin xiong xiong Sidao Ni State Key Laboratory of Geodesy and Earth's Dynamics Institute of Geodesy and GeophysicsChinese Academy of Sciences

A linear projection approach is developed to present geoscience research result in planar coordinate system projected from spherical coordinate system. Here, the sphere is intersected by a plane and its surface is projected onto the plane. In order to keep the projected coordinate system orthogonal, and minimize the distortion, one axis of the planar coordinate system is chosen in our projection based on the shape of the region to be projected, and the other axes can be chosen arbitrarily or based on the constraint of the orthogonality. In the new method the projection is self-contained. The forward projection can be fully projected backward without loss of precision. The central area of the sphere will be projected to the planar system without distortion, and the latitudinal length in the rotated spherical system keeps constant during the projecting process. Only the longitudinal length in the rotated spherical system changes with the rotated latitude. The distortion of the projection therefore, overall, is small and suitable for geoscience studies.

关键词： adaptive 2D projection linear planar geoscience

Micro-Macro Scale Relationship in Creep Deformation of Ultra High Molecular Weight Polyethylene

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Chinese Journal of Polymer Science 2021年第12期39卷 1665-1672页

作者： Bi-jin xiong Zhen-Xian Chen Jian Kang Key Laboratory of Materials Chemistry for Energy Conversion and Storage(HUST)of Ministry of Education School of Chemistry and Chemical EngineeringHuazhong University of Science and Technology(HUST)Wuhan 430074China State Key Laboratory of Polymer Materials Engineering Polymer Research Institute of Sichuan UniversityChengdu 610065China

Macroscopic and microscale creep deformations of UHMWPE were investigated by using in situ SAXS.A methodology for the measurement of the local creep deformation of inter-lamellar amorphous phase has been *** local strain of inter-lamellar amorphous phase(£a)and macroscopic strain(£macro)were evaluated and they were compared to study the relati on ship betwee n macroscopic and microscale creep deformation of *** of them exhibit two deformation regions against creep *** entanglements show a strong impact on both the macroscopic and local inter-lamellar amorphous phase creep behavior and they can be well correlated to the molecular weight between two entanglements estimated from strain-hardening *** to the macroscopic creep deformation,local inter-lamellar amorphous layers have a smaller creep *** the local creep measurement,the apparent modulus of inter-lamellar amorphous phase can also be estimated(200hous PE,which can be well explained by the confinement of the lamellar stacks and the enhancement of the amorphous phase with the relatively high concentration of *** study provides a useful means and quantitative data for achieving the scale transition between the micro and the macro structural levels for the study of viscos-elastic deformation.

关键词： Ultra-high molecular weight polyethylene Creep Small angle X-ray scattering Microscale

Coupling mechanism of activated carbon mixed with dust for flue gas desulfurization and denitrification

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Journal of Environmental Sciences 2020年第12期32卷 205-214页

作者： Junxiang Guo Yuran Li jin xiong Tingyu Zhu Beijing Engineering Research Center of Process Pollution Control National Engineering Laboratory for Hydrometallurgical Cleaner Production TechnologyInstitute of Process EngineeringChinese Academy of SciencesBeijing 100190China Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China

To clarify the effect of coking dust, sintering dust and fly ash on the activity of activated carbon for various industrial flue gas desulfurization and denitrification, the coupling mechanism of the mixed activated carbon and dust was investigated to provide theoretical reference for the stable operation. The results show that coking dust had 34% desulfurization efficiency and 10% denitrification efficiency;correspondingly, sintering dust and fly ash had no obvious desulfurization and denitrification activities. For the mixture of activated carbon and dust, the coking dust reduced the desulfurization and denitrification efficiencies by blocking the pores of activated carbon, and its inhibiting effect on activated carbon was larger than its own desulfurization and denitrification activity. The sintering dust also reduced the desulfurization efficiency on the activated carbon while enhancing the denitrification efficiency. Fly ash blocked the pores of activated carbon and reduced its reaction activity. The reaction activity of coking dust mainly came from the surface functional groups, similar to that of activated carbon. The reaction activity of sintering dust mainly came from the oxidative property of Fe_2O _3, which oxidized NO to NO_2 and promoted the fast selectively catalytic reduction(SCR) of NO to form N_2. Sintering dust was activated by the joint action of activated carbon, and both had a coupling function. Sintering dust enhanced the adsorption and oxidation of NO, and activated carbon further promoted the reduction of NO_x by NH_3;thus, the denitrification efficiency increased by 5%-7% on the activated carbon.

关键词： Activated carbon Coking dust Sintering dust Fly ash Coupling effect

Crack Fault Diagnosis and Location Method for a Dual-Disk Hollow Shaft Rotor System Based on the Radial Basis Function Network and Pattern Recognition Neural Network

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Chinese Journal of Mechanical Engineering 2023年第2期36卷 180-197页

作者： Yuhong jin Lei hou Zhenyong Lu Yushu Chen School of Astronautics Harbin Institute of TechnologyHarbin 150001China Institute of Dynamics and Control Science Shandong Normal UniversityJi’nan 250014China

The crack fault is one of the most common faults in the rotor system,and researchers have paid close attention to its fault ***,most studies focus on discussing the dynamic response characteristics caused by the crack rather than estimating the crack depth and position based on the obtained vibration *** this paper,a novel crack fault diagnosis and location method for a dual-disk hollow shaft rotor system based on the Radial basis function(RBF)network and Pattern recognition neural network(PRNN)is ***,a rotor system model with a breathing crack suitable for a short-thick hollow shaft rotor is established based on the finite element method,where the crack's periodic opening and closing pattern and different degrees of crack depth are ***,the dynamic response is obtained by the harmonic balance *** adjusting the crack parameters,the dynamic characteristics related to the crack depth and position are analyzed through the amplitude-frequency responses and waterfall *** analysis results show that the first critical speed,first subcritical speed,first critical speed amplitude,and super-harmonic resonance peak at the first subcritical speed can be utilized for the crack fault *** on this,the RBF network and PRNN are adopted to determine the depth and approximate location of the crack respectively by taking the above dynamic characteristics as *** results show that the proposed method has high fault diagnosis *** research proposes a crack detection method adequate for the hollow shaft rotor system,where the crack depth and position are both unknown.

关键词： Hollow shaft rotor Breathing crack Radial basis function network Pattern recognition neural network Machine learning

A new eutriconodont mammal from the early Cretaceous Jehol Biota of Liaoning, China

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Chinese Science Bulletin 2014年第5期59卷 546-553页

作者： Shilin hou jin Meng Department of Geology Northeastern University Paleontological Institute Shenyang Normal University Division of Paleontology American Museum of Natural History Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences

A new genus and species of eutriconodont mammal,Chaoyangodens lii *** ***.,from the Dawangzhangzi bed of Yixian Formation,Lingyuan,Liaoning,is *** new species has a tooth formula I5-C1-P1-M3/i4-c1-p1-m4,unique among eutriconodonts in having only one premolar in lower and upper jaws,respectively,and a distinctive diastema between the canine and the *** simple incisors and reduced premolars show a mosaic combination of primitive and derived *** new taxon adds to the diverse group of Jehol *** the known species from at least three horizons,there seems no evolutionary trend in morphology that is recognizable,except for that larger species are all from the Lujiatun bed of the Yixian Fm.A thorough and systematic analysis involving all the Jehol eutriconodonts is needed to understand their phylogenetic relationships.

关键词：热河生物群哺乳动物早白垩世辽宁中国新分类群外部形态亲缘关系

Enhanced Hardness of Transparent HAp Ceramic by Microstructure Refinement

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Journal of Wuhan University of Technology(Materials Science) 2019年第1期34卷 254-258页

作者： ZENG Hui jin Xin xiong Yan Wuhan Institute of Marine Electric Propulsion School of Materials Science & Engineering Hubei Province Key Laboratory of Green Materials for Light Industry Hubei University of Technology

Transparent hydroxyapatite(HAp) ceramics with the grain size ranging 86-1 300 nm were successfully synthesized by spark plasma sintering(SPS) at 925-1 200 ℃. All the sample achieved final density higher than 99.7%. The phase stability was identified by X-ray diffraction(XRD) and Fourier transform infrared spectroscopy(FTIR). The experimental results indicate that there is no decomposition or dehydroxylation during the SPS processes. The influences of microstructure refinement on the hardness were investigated using HallPetch(H-P) relationship, and the hardness of transparent HAp ceramic increases with the decrease of grain size. It is demonstrated that the grain boundaries and defects play important roles on the hardness.

关键词： hydroxyapatite transparent hardness grain size,microstructure refinement

High-order targeted essentially non-oscillatory scheme for two-fluid plasma model

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Applied Mathematics and Mechanics(English Edition) 2023年第6期44卷 941-960页

作者： Yuhang hou Ke jin Yongliang FENG Xiaojing ZHENG School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Institute of Extreme Mechanics Northwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of Space Extreme Detection Xi’an 710071China Research Center for Applied Mechanics Xidian UniversityXi’an 710071China

The weakly ionized plasma flows in aerospace are commonly simulated by the single-fluid model,which cannot describe certain nonequilibrium phenomena by finite collisions of particles,decreasing the fidelity of the *** on an alternative formulation of the targeted essentially non-oscillatory(TENO)scheme,a novel high-order numerical scheme is proposed to simulate the two-fluid plasmas *** numerical flux is constructed by the TENO interpolation of the solution and its derivatives,instead of being reconstructed from the physical *** present scheme is used to solve the two sets of Euler equations coupled with Maxwell's *** numerical methods are verified by several classical plasma *** results show that compared with the original TENO scheme,the present scheme can suppress the non-physical oscillations and reduce the numerical dissipation.

关键词： plasma high-order scheme targeted essentially non-oscillatory(TENO)scheme two-fluid model

An effective crack position diagnosis method for the hollow shaft rotor system based on the convolutional neural network and deep metric learning

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Chinese Journal of Aeronautics 2022年第9期35卷 242-254页

作者： Yuhong jin Lei hou Yushu CHEN Zhenyong LU School of Astronautics Harbin Institute of TechnologyHarbin 150001China Institute of Dynamics and Control Science Shandong Normal UniversityJi'nan 250014China

In recent years, the crack fault is one of the most common faults in the rotor system and it is still a challenge for crack position diagnosis in the hollow shaft rotor system. In this paper, a method based on the Convolutional Neural Network and deep metric learning(CNN-C) is proposed to effectively identify the crack position for a hollow shaft rotor system. Center-loss function is used to enhance the performance of neural network. Main contributions include: Firstly, the dynamic response of the dual-disks hollow shaft rotor system is obtained. The analysis results show that the crack will cause super-harmonic resonance, and the peak value of it is closely related to the position and depth of the crack. In addition, the amplitude near the non-resonant region also has relationship with the crack parameters. Secondly, we proposed an effective crack position diagnosis method which has the highest 99.04% recognition accuracy compared with other algorithms. Then,the influence of penalty factor on CNN-C performance is analyzed, which shows that too high penalty factor will lead to the decline of the neural network performance. Finally, the feature vectors are visualized via t-distributed Stochastic Neighbor Embedding(t-SNE). Naive Bayes classifier(NB) and K-Nearest Neighbor algorithm(KNN) are used to verify the validity of the feature vectors extracted by CNN-C. The results show that NB and KNN have more regular decision boundaries and higher recognition accuracy on the feature vectors data set extracted by CNN-C,indicating that the feature vectors extracted by CNN-C have great intra-class compactness and inter-class separability.

关键词： Convolutional neural networks Cracked rotor Deep metric learning Fault diagnosis Hollow shaft rotor