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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

Geochemistry and petrology of superpure quartzites from East Sayan Mountains, Russia

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Acta Geochimica 2019年第1期38卷 22-39页

作者： A.M.Fedorov V.A.Makrygina A.I.Nepomnyaschikh A.P.Zhaboedov A.V.Parshin V.F.Posokhov Yu.V.Sokolnikova A.P.Vinogradov institute of Geochemistry SB ras Irkutsk National research Technical University Irkutsk Scientific Center SB ras Irkutsk State University Geological institute SB ras

Quartzites are widespread within Earth's lithosphere, but their highly pure varieties occur quite infrequently. With the development of alternative energy sources, including solar, and with increasing demand for high-purity quartz for optics, interest has risen in highpurity silicon-bearing materials. The quartzites discovered in the southeast part of the Eastern Sayan Mountains are particularly attractive for exploration in terms of their raw material quality and feasibility to be enriched. For this reason, their genesis also merits study. Available geochemical data show that chemogenic(d^(18)O>29.2%)siliceous-carbonate sediments of the Irkut Formation are fairly pure(impurity elements 0.9% impurities, but later, under the action of sliding slabs of ophiolite dynamothermal treatment reduced impurities to < 100 ppm, resulting in ‘‘superquartzites' '(highly pure quartzites). The presence of only minor structural impurities is due to the enrichment capacity of superquartzites to 10.1 ppm(7.2 ppm under special conditions) of 10 elements: Fe, Al, Ti, Ca, Mg, Cu,Mn, Na, K, and Li.

关键词： High-purity quartz Superquartzite Gravitational sliding Dynamic metamorphism Recrystallization

First observation results of Macao Science Satellite-1 on lightning-induced electron precipitation

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Science China Earth Sciences 2025年第1期 1-10页

作者： Yongping WANG Yixin SUN Qiugang ZONG Gaopeng LU Xudong GU Ze-Jun HU Bin LI Key Laboratory for Polar Science Ministry of Natural Resources Polar Research Institute of China institute of space Physics and Applied Technology Peking University State Key Laboratory of Lunar and Planetary Science Macau University of Science and Technology School of Earth and space Sciences University of Science and Technology of China School of Electronic Information Wuhan University

The Medium-energy Electron Spectrometers(MES) is a space-borne instrument onboard Macao Science Satellite-1(MSS-1) dedicated to monitoring the typical charged particle radiation characteristics in the satellite orbit and the process of their occurrence and development, including short bursts of lightning-induced electron precipitation(LEP).This paper presents the first results of the LEP measurements by the MSS-1.47 LEP events are identified with the routine operation for 3 months since satellite launch, all within the range of 1.5

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Measurement of bidirectional reflection distribution function on material surface

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Chinese Optics Letters 2009年第1期7卷 88-91页

作者：张伟汪洪源王治乐 research Center for space Optical Engineering Harbin Institute of Technology

Two automatic measurement methods of bidirectional reflection distribution function （BRDF） are presented based on absolute and relative definition. Measurement principle and scheme of the methods are analyzed. A real-time measurement device is developed, the measurement spectral range of which is from ultraviolet to near infrared with 2.4-nm wavelength resolution, and the angular range is 0° - 360° in azimuth angle and 0° - 85° in zenith angle with 0.01° angle resolution. Absolute measurements of BRDF on tinfoil and ceramic tile are performed and the test materials present apparent specular reflection characteristics. The theoretical error in the experiment is about 6.05%. The BRDF measurement results are closely related to the precision of measurement platform, the sensitivity of measurement instrument, and the stability of illuminating light source.

关键词： Distribution functions Fabrics Light Light sources Lighting Probability density function Reflection Time measurement

Comparison of strapdown inertial navigation algorithm based on rotation vector and dual quaternion

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Chinese Journal of Aeronautics 2013年第2期26卷 442-448页

作者： Wang Zhenhuan Chen Xijun Zeng Qingshuang space Control and Inertial Technology research Center Harbin Institute of Technology

For the navigation algorithm of the strapdown inertial navigation system, by comparing to the equations of the dual quaternion and quaternion, the superiority of the attitude algorithm based on dual quaternion over the ones based on rotation vector in accuracy is analyzed in the case of the rotation of navigation frame. By comparing the update algorithm of the gravitational velocity in dual quaternion solution with the compensation algorithm of the harmful acceleration in traditional velocity solution, the accuracy advantage of the gravitational velocity based on dual quaternion is addressed. In view of the idea of the attitude and velocity algorithm based on dual quaternion, an improved navigation algorithm is proposed, which is as much as the rotation vector algorithm in computational complexity. According to this method, the attitude quaternion does not require compensating as the navigation frame rotates. In order to verify the correctness of the theoretical analysis, simulations are carried out utilizing the software, and the simulation results show that the accuracy of the improved algorithm is approximately equal to the dual quaternion algorithm.

关键词： Dual quaternion Inertial navigation system Navigation algorithm Quaternion Rotation vector

Investigation of Total Absorption of Radio Waves in High Latitude Ionosphere

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Plasma Science and Technology 2014年第9期16卷 833-836页

作者：史建魁王铮陶伟 G.A.ZHEREBTSOV E.B.ROMANOVA K.G.RATOVSKY State Key Laboratory of space Weather NSSC/CAS institute of Solar-Terrestrial Physics SB/RAS Irkutsk 664033 Russia

Using the digisonde data observed at ionospheric station Norilsk （Dip lat. 60~N） in 2006, a statistical study on the characteristics of the ionospheric plasma total absorption of radio waves （IPTAR） was performed. In the winter and some months of equinox, the IPTAR mainly occurred in the nighttime and the highest occurrence rate could be up to 90%. In the summer, the occurrence was relatively low and the differences between nighttime and daytime occurrence reduced. The total duration of IPTAR seemed longer around the winter than that around the summer. The occurrence of IPTAR events ascended as the Kp index increased. The frequent precipitation of energetic particles into the ionospheric plasma in the auroral belt may be the main cause of the IPTAR events.

关键词： ionosphere radio waves total absorption

Influence of ZrB2 Nanoparticles on the Mechanical and Thermal Behaviors of Carbon Nanotube Reinforced Resol Composite

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Journal of Materials Science & Technology 2016年第7期32卷 611-616页

作者： Zahra Amirsardari Rouhollah Mehdinavaz-Aghdam Masoud Salavati-Niasari Mohammad Reza Jahannama institute of Nano Science and Nano Technology University of Kashan. Kashan. Iran Department of Nanotechnology. space Transportation research institute Iranian Space Research Center Tehran lran

The present study focuses on the thermal response of carbon fiber-reinforced phenolic composites, where the matrix has been modified with different reinforcements. Two types of materials, multiwalled carbon nanotubes and zirconium diboride （ZrB2）, were used in a new design of mixture to produce the heat- resistant ablative composite system. The CNT/ZrB2/carbon/phenolic nanocomposite （Z/NT-CR） system corresponding to CNT/carbon/phenolic nanocomposite （NT-CR） showed a reasonable decrease in mass loss and the ablation rate as compared to carbon/phenolic composite （CR）. However, substantial drop in two factors was found for Z/NT-CR as compared to carbon/phenolic and NT-CR. Ablation mechanisms for all three composites were investigated by thermal gravimetric analysis in conjunction with micro- structural studies using a field emission scanning electron microscope. The microstructural studies revealed that CNTs acted as an ablation resistant phase for protection against 2000 ℃, and the conversion from ZrB2 to ZrO2 played an important role as an insulator in the performance of char layer in the ablation resistance.

关键词： Multiwalled carbon nanotubes (MWCNTs)Zirconium diboride nanoparticles (ZrB2)Carbon/phenolic compositeThermal stabilityAblation performance