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Optimal design of near-Earth asteroid sample-return trajectories in the Sun–Earth–Moon system

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Acta Mechanica Sinica 2016年第4期32卷 753-770页

作者： Shengmao He Zhengfan zhu Chao Peng Jian Ma xiaolong zhu Yang Gao Key Laboratory of Space Utilization Technology and Engineering Center for Space UtilizationChinese Academyof SciencesBeijing 100094China University of Chinese Academy of Sciences Beijing 100049China Academy of Opto-Electronics Chinese Academy of SciencesBeijing 100094China

In the 6th edition of the Chinese Space Trajectory Design Competition held in 2014, a near-Earth asteroid sample-return trajectory design problem was released, in which the motion of the spacecraft is modeled in multi-body dynamics, considering the gravitational forces of the Sun, Earth, and Moon. It is proposed that an electric-propulsion spacecraft initially parking in a circular 200-kin-altitude low Earth orbit is expected to rendezvous with an asteroid and carry as much sample as possible back to the Earth in a 10-year time frame. The team from the Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences has reported a solution with an asteroid sample mass of 328 tons, which is ranked first in the competition. In this article, we will present our design and optimization methods, primarily including overall analysis, target selection, escape from and capture by the Earth-Moon system, and optimization of impulsive and low-thrust trajectories that are modeled in multi-body dynamics. The orbital resonance concept and lunar gravity assists are considered key techniques employed for trajectory design. The reported solution, preliminarily revealing the feasibility of returning a hundreds-of-tons asteroid or asteroid sample, envisions future space missions relating to near-Earth asteroid exploration.

关键词： Near-Earth asteroid. Sample-return trajectory.Space trajectory design competition Orbital resonance Lunar gravity assist

SEAWATER CORROSION OF A Cu-Ni ALLOY IN INTERMITTENT IMMERSION

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中国有色金属学会会刊：英文版 1997年第3期7卷 51-54页

作者： zhu, xiaolong Lin, Leyun Li, Zhongjian Lei, Tingquan General Research Inst of Nonferrous Metals Beijing China

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ＳＥＡＷＡＴＥＲＣＯＲＲＯＳＩＯＮＯＦＡＣｕＮｉＡＬＬＯＹＩＮＩＮＴＥＲＭＩＴＴＥＮＴＩＭＭＥＲＳＩＯＮ①ＺｈｕＸｉａｏｌｏｎｇ，ＬｉｎＬｅｙｕｎ，ＬｉＺｈｏｎｇｊｉａｎＧｅｎｅｒａｌＲｅｓｅａｒｃｈＩｎｓｔｉｔｕｔｅｏｆＮｏｎＦｅｒｒｏｕｓＭｅ...

关键词： Cu Ni alloy seawater corrosion intermittent immersion

Characteristics of strontium isotopes and their implications in the Qixing Cave of Guizhou, China

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Chinese Science Bulletin 2011年第7期56卷 670-675页

作者： zhu xiaolong WANG ShiJie LUO WeiJun State Key Laboratory of Environmental Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550002China Graduate University of Chinese Academy of Sciences Beijing 100049China

The strontium isotopic compositions (87Sr/86Sr) of samples including soils, bedrock, soil waters, drip waters and their corresponding speleothems in the Qixing Cave (QXC), Guizhou Province, China, were systemically measured and analyzed. The results indicate that there are significant Sr isotopic differences among samples. The mean 87Sr/86Sr ratios in drip water for the samples 1#, 4# and 9# were 0.709568, 0.709139 and 0.708761, respectively, which possibly result from different flow paths, residence times, and other hydrogeological processes in the unsaturated zone overlying QXC. Meanwhile, levels of 40.8%, 57.6% and 72.4% of Sr in drip waters for 1#, 4# and 9#, respectively, were derived from bedrock dissolution, which was calculated by the mixture model of the two end-members (soil and bedrock). There is, however, no positive correlation between the relative proportion from bedrock dissolution (δ13C value is 1.8‰) and drip water δ13CDIC values. The mean drip water δ13CDIC value in 1# is the heaviest (–4.5‰) with the lowest contribution rate of bedrock dissolution, whereas the value in 9# is the lightest (–9.3‰) with the highest contribution rate of bedrock dissolution. The proportion from host rock dissolution in 4# is higher than that in 1# and lower than that in 9#, while its mean drip water δ13CDIC value (–8.6‰) is higher than that of 9# and lower than that for 1#. This suggests that the prior calcite precipitation (PCP) processes in the unsaturated zone overlying the cave are responsible for the δ13CDIC value differences between different drip waters, and not bedrock dissolution. Furthermore, this study also demonstrates that the 87Sr/86Sr ratios of speleothems in the 1# and 4# mainly reflect the variation in the relative proportions from the soil system (soil water) and bedrock dissolution overlying the cave. It is, therefore, feasible to use the strontium isotopic signals of speleothems as an indicator for soil chemical weathering intensity, and consequentl

关键词：锶同位素同位素特征贵州省中国洞穴堆积物同位素组成流动路径停留时间

Blind source separation with unknown and dynamically changing number of source signals

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Science in China(Series F) 2006年第5期49卷 627-638页

作者： YE Jimin ZHANG Xianda zhu xiaolong Key Laboratory for Radar Signal Processing Xidian University Xi'an 710071 China Department of Automation State Key Laboratory of Intelligent Technology and Systems Tsinghua University Beijing 100084 China

The contrast function remains to be an open problem in blind source separation （BSS） when the number of source signals is unknown and/or dynamically changed. The paper studies this problem and proves that the mutual information is still the contrast function for BSS if the mixing matrix is of full column rank. The mutual information reaches its minimum at the separation points, where the random outputs of the BSS system are the scaled and permuted source signals, while the others are zero outputs. Using the property that the transpose of the mixing matrix and a matrix composed by m observed signals have the indentical null space with probability one, a practical method, which can detect the unknown number of source signals n, ulteriorly traces the dynamical change of the sources number with a few of data, is proposed. The effectiveness of the proposed theorey and the developed novel algorithm is verified by adaptive BSS simulations with unknown and dynamically changing number of source signals.

关键词： blind source separation independent component analysis natural gradient mutual information contrast function neural networks.

A new design of foam spray nozzle used for precise dust control in underground coal mines

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International Journal of Mining Science and Technology 2016年第2期26卷 241-246页

作者： Han Fangwei Wang Deming Jiang Jiaxing zhu xiaolong College of Safety Science and Engineering Liaoning Technical UniversityHuludao 125105China Faculty of Safety Engineering China University of Mining&TechnologyXuzhou 221116China

In order to improve the utilization rate of foam,an arc jet nozzle was designed for precise dust *** theoretical analysis,the different demands of foam were compared amongst arc jets,flat jets and full cone jets when the dust source was covered identically by *** is proved that foam consumption was least when an arc jet was *** production capability of an arc jet nozzle under different conditions was investigated through *** results show that with the gas liquid ratio(GLR)increasing,the spray state of an arc jet nozzle presents successively water jet,foam jet and *** a reasonable working condition range of foam production and a fixed GLR,foam production quantity increases at first,and then decreases with the increase of liquid supply *** the inner diameter of the nozzle is 14 mm,the best GLR is 30 and the optimum liquid supply quantity is0.375 m^3/*** results of field experiments show that the total dust and respirable dust suppression efficiency of arc jet nozzles is 85.8%and 82.6%respectively,which are 1.39 and 1.37 times higher than the full cone nozzles and 1.20 and 1.19 times higher than the fiat nozzles.

关键词： Dust control Precise spray Arc jet Gas liquid ratio(GLR) Dust suppression efficiency

Transformer Partial Discharge Monitoring Based on Optical Fiber Sensing

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Photonic Sensors 2014年第2期4卷 137-141页

作者： Kun WANG Xinglin TONG xiaolong zhu National Engineering Laboratory for Fiber Optic Sensing Technology Wuhan University of Technology Wuhan430070 China

The power transformer is the most important equipment of the high voltage power grid, however, some traditional methods of online partial discharge monitoring have some limitations. Based on many advantages of the optical fiber sensing technology, we have done some research on fiber optics Fabry-Perot （FP） sensing which can be useful for the transformer on online partial discharge monitoring. This research aimed at improving the reliability of power system safety monitoring. We have done some work as follows： designing a set for fiber optics FP sensor preparation, according to the fabrication procedure strictly making out the sensors, building a reasonable signal demodulation system for fiber optics FP sensing, doing a preliminary analysis about online partial discharge signal monitoring, including the research on different discharge intensities with the same measuring distance and different measuring distances with the same discharge intensity, and then making a detailed analysis of the experimental results.

关键词： Partial discharge fiber FP sensor diaphragm effective reflectivity

Effect of Microstructure and Sulfide on Corrosion of Cu-Ni Alloys in Seawater

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Journal of Materials Science & Technology 2000年第4期16卷 411-415页

作者： xiaolong zhu (General Research Institute for Nonferrous Metals, Beijing 100088, China) General Research Institute for Nonferrous Metals Beijing 100088 China

The microstructure and the corrosion product films have been investigated on Cu-Ni alloys by TEM, SEM, AES and electrochemical technique as well as natural seawater exposure tests. Experimental results showed that the alloys had two kinds of microstructure, i.e. recrystallizatjon and incomplete recrystallization. In synthetic seawater containing 2x10^-6 S^2-, the stability of the alloy increased with the increase of deformation and annealing temperature, i.e., the degree of recrystallization. After exposure to natural seawater for different periods of time, the corrosion product films of the recrystallized alloy were rich in Ni and compact, and there were cracks in the outer layer which contained a small amount of S; the films of the alloy of incomplete recrystallization became thick, loose and porous, and obviously of layered structure, and the intergranular corrosion took place in the underlying substrate Besides, a great amount of seawater substance existed in the outer layer and some sulfur was found within the grain boundaries that prefer to corrode. The accelerating effect of sulfides in corrosion of Cu-Ni alloys in seawater is attributed to the coexistence and absorption of sulfides and carbides promoting the preference of corrosion where they absorb, and the formation of dissolvable Cu2S results in keeping the surface of the alloys in the active state.

关键词： Effect of Microstructure and Sulfide on Corrosion of Cu-Ni Alloys in Seawater Cu Ni

High Performance Work Systems and Employee Creativity： The Mediating Effect of Knowledge Sharing

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Frontiers of Business Research in China 2014年第3期8卷 367-387页

作者： Chunling zhu xiaolong Chen School of Business Renmin University of China Beijing 100872 China

Employee creativity is both the core element of a firm＇s innovation capabilities and the sources for its growth. To improve an organization＇s ability to innovate, it is necessary to improve the creativity of its employees. Based on theories from strategic human resource management, creativity and organizational learning, this paper investigates the relationship between high performance work systems and employee creativity and explores the role knowledge sharing plays in their relationship. A questionnaire is designed and administered to a group of part-time executive students in the winter of 2012. Two hundred students are invited to answer the survey questions with 117 valid responses. Data are collected and processed by using statistical regressions. The empirical findings reveal that high performance work systems positively affect knowledge sharing and employee creativity. Knowledge sharing plays a mediating role in the relationship between high performance work systems and employee creativity. Implications for practice and future research are discussed.

关键词： high performance work systems (HPWS) knowledge sharing,employee creativity

Interaction between energetic-ions and internal kink modes in a weak shear tokamak plasma

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Plasma Science and Technology 2022年第2期24卷 28-35页

作者： xiaolong zhu Feng WANG Wei CHEN Zhengxiong WANG Key Laboratory of Materials Modification by Laser Ion and Electron Beams(Ministry of Eduction)School of PhysicsDalian University of TechnologyDalian 116024People's Republic of China Key Laboratory of Materials Modification by LaserIon and Electron Beams(Ministry of Eduction)School of PhysicsDalian University of TechnologyDalian 116024People's Republic of China Joint Laboratory for Fusion Product and Energetic Particles Southwestern Institute of PhysicsChengdu 610041People's Republic of China

Based on the conventional tokamak HL-2 A-like parameters and profiles,the linear properties and the nonlinear dynamics of non-resonant kink mode(NRK)and non-resonant fishbone instability(NRFB)in reversed shear tokamak plasmas are investigated by using the global hybrid kinetic-magnetohydrodynamic nonlinear code M3 *** work mainly focuses on the effect of passing energetic-ions on the NRK and NRFB instabilities,which is different from the previous *** is demonstrated that the NRFB can be destabilized by the passing energeticions when the energetic-ion betaβ;exceeds a critical *** transition from NRK to NRFB occurs when the energetic-ion betaβ;increases to above a critical *** resonance condition responsible for the excitation of NRFB is interestingly found to be satisfied atω;+ω;≈ω,whereω;is the toroidal motion frequency,ω;is the poloidal motion frequency andωis the mode *** nonlinear evolutions of NRFB’s mode structures and Poincaréplots are also analyzed in this work and it is found that the NRFB can induce evident energeticion loss/redistribution,which can degrade the performance of the *** findings are conducive to understanding the mechanisms of NRFB induced energetic-ion loss/redistribution through nonlinear wave-particle interaction.

关键词： energetic-ions non-resonant fishbone weak shear loss/redistribution