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Strongly Singular Integral Operators on Weighted Hardy Space

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Acta Mathematica Sinica,English Series 2006年第3期22卷 767-772页

作者： jun Feng LI shan Zhen LU Department of Mathematics Beijing Normal University

In this paper, we obtain that a strongly singular integral operator is bounded on Lω^p. space for 1 〈 p 〈 ∞. We also obtain that a strongly singular integral operator is a bounded operator from Hω^p, to Lω^p for some weight w and 0 〈 p ≤ 1. And by an atomic decomposition, we obtain that a strongly singular integral operator is a bounded operator on Hω^p for some w and 0 〈 p ≤ 1.

关键词： Strongly singular Calderón-Zygmund operators Hardy spaces A weight

Chemical mixing by turbulent convection in the overshooting region below the convective envelope of RGB stars

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Research in Astronomy and Astrophysics 2011年第11期11卷 1351-1370页

作者： xiang-jun Lai Yan Li National Astronomical Observatories / Yunnan Observatory Chinese Academy of SciencesKunming 650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy ofSciences Kunming 650011 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

Based on the turbulent convection model （TCM）, we investigate chemical mixing in the bottom overshooting region of the convective envelope of intermediatemass stars, focusing on its influence on the formation and extension of blue loops in the Hertzsprung-Russell （HR） diagram. A diffusive mixing model is adopted during the Red Giant Branch （RGB） phase. The properties of the blue loop are changed by modification of the element profiles above the H-burning shell, which results from the incomplete mixing in the bottom overshooting region when the stellar model evolves up along the RGB. Such modification of the element profiles will lead to an increase of opacity in the region just above the H-burning shell and a decrease of opacity in the outer homogeneous convection zone, which will result in a quick decrease of the H-shell nuclear luminosity LH when the stellar model evolves from the RGB tip to its bottom and, finally, a much weaker and smaller convection zone will be obtained in the stellar envelope. This helps to form a longer blue loop. The extension of the blue loop is very sensitive to the parameters （Cx and αTCM） of the diffusive mixing model and of the TCM. The results mainly show that： 1） comparing the results of the classical model with the mixing-length theory, the lengths of the obtained blue loops with different combinations of the values of Cx and αTCM are all increased and the length of the blue loop increases with the values of parameters Cx and αTCM; 2） the diffusive mixing model can significantly extend the time of stellar models lingering on the blue side of the HR diagram, even though the length of the blue loop for the 7M⊙ star has a less prominent difference between the classical and diffusive mixing model; 3） both the observations referring to the location of the Cepheid instability strip and the number ratio NB/NR of blue to red evolved stars in the Galactic open clusters can confine the two parameters in a range of 0.5 ≤ αLTCM ≤ 0.9 and 10-5 ≤

关键词： stars convection-star interiors-star HR diagram-blue loops-Cepheids-Galactic open clusters

Corrosion behaviors of thermally grown oxide films on Fe-based bulk metallic glasses

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International Journal of Minerals,Metallurgy and Materials 2012年第8期19卷 726-732页

作者： Hong-xiang Li shan-lin Wang Yeonuk Jeong Seonghoon Yi State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China. School of Aeronautical Manufacturing Engineering Nanchang Hangkong University Nanchang 330063 China. Department of Electronic Materials Science and Engineering Kyungpook National University Daegu 702-701 South Korea. Department of Materials Science and Metallurgy Kyungpook National University Daegu 702-701 South Korea.

Oxide films formed on the surfaces of Fe-based bulk metallic glasses in the temperature range between 373 K and 573 K were characterized and their effects on the corrosion behaviors were investigated by microstructural and electrochemical analysis. The oxide film formed at 573 K is iron-rich oxide and it exhibits an n-type semiconductor at a higher potential than 0.35 V and a p-type semiconductor at a lower potential than 0.35 V. Capacitance measurements show that the donor density decreases with the increase in oxidation temperature, while the thickness of the space charge layer increases with the oxidation temperature rising. The result of immersion tests shows that the mass loss rate increases with the oxidation temperature rising. Therefore, the correlation between microstructure and corrosion resistance needs to be proposed because the corrosion resistance is deteriorated with the development of the oxide films.

关键词： bulk metallic glass oxide films corrosion capacitance

Non-uniform temperature distribution of the main reflector of a large radio telescope under solar radiation

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Research in Astronomy and Astrophysics 2021年第11期21卷 233-242页

作者： shan-xiang Wei De-Qing Kong Qi-Ming Wang Key Laboratory of Lunar and Deep Space Exploration National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

The non-uniform temperature distribution of the main reflector of a large radio telescope may cause serious deformation of the main reflector,which will dramatically reduce the aperture efficiency of a radio *** study the non-uniform temperature field of the main reflector of a large radio telescope,numerical calculations including thermal environment factors,the coefficients on convection and radiation,and the shadow boundary of the main reflector are first *** addition,the shadow coverage and the non-uniform temperature field of the main reflector of a 70-m radio telescope under solar radiation are simulated by finite element *** simulation results show that the temperature distribution of the main reflector under solar radiation is very uneven,and the maximum of the root mean square temperature is 12.3℃.To verify the simulation results,an optical camera and a thermal imaging camera are used to measure the shadow coverage and the non-uniform temperature distribution of the main reflector on a clear *** the same time,some temperature sensors are used to measure the temperature at some points close to the main reflector on the backup *** has been verified that the simulation and measurement results of the shadow coverage on the main reflector are in good agreement,and the cosine similarity between the simulation and the measurement is above 90%.Despite the inevitable thermal imaging errors caused by large viewing angles,the simulated temperature field is similar to the measured temperature distribution of the main reflector to a large *** temperature trend measured at the test points on the backup structure close to the main reflector without direct solar radiation is consistent with the simulated temperature trend of the corresponding points on the main reflector with the solar *** is credible to calculate the temperature field of the main reflector through the finite element *** work can provide valuab

关键词： large radio telescope finite element analysis solar radiation shadow coverage temperature distribution

Effect of the alidade thermal behavior on the pointing accuracy of a large radio telescope

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Research in Astronomy and Astrophysics 2021年第6期21卷 253-262页

The alidade’s non-uniform temperature field of a large radio telescope is very obvious under solar *** a radio telescope’s pointing errors,caused by the alidade deformation under solar radiation,is significant to improve the telescope’s pointing *** study the effect of the alidade thermal behavior on the pointing accuracy of a large radio telescope,a temperature experiment is first carried out in a 70-m radio telescope on a sunny *** to the measured results,the temperature distribution rule of the alidade is summarized *** addition,the alidade’s temperature field is calculated by finite element thermal *** simulated results are proved to be in good agreement with the experimental ***,the alidade deformation under solar radiation is computed by finite element thermalstructure coupling *** telescope’s pointing errors caused by alidade deformation are estimated via the alidade’s node *** final results show that the effect of alidade thermal behavior on the telescope’s elevation pointing errorsΔε2+Δεr is much more than the effect on the telescope’s crosselevation pointing errorsΔε*** maximum ofΔε2+Δεr is more than 45″,while the maximum ofΔε1 is less than 6″.This study can provide valuable references for improving the pointing accuracy of large radio telescopes.

关键词： telescopes finite element analysis thermal behavior pointing accuracy

First-principles calculations of solute–vacancy interactions in aluminum

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Chinese Physics B 2020年第6期29卷 369-373页

作者： Sha-Sha Zhang Zheng-jun Yao xiang-shan Kong Liang Chen Jing-Yu Qin College of Materials and Technology Nanjing University of Aeronautics and AstronauticsNanjing 211106China Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials Ministry of EducationShandong UniversityJinan 250061China

The interactions of solute atoms with vacancies play a key role in diffusion and precipitation of alloying elements,ultimately influencing the mechanical properties of aluminum *** this study,first-principles calculations are systematically performed to quantify the solute–vacancy interactions for the 3d–4p series and the 4d–5p *** solute–vacancy interaction gradually transforms from repulsion to attraction from left to *** solute–vacancy binding energy is sensitive to the supercell size for elements at the *** behaviors of the solute–vacancy binding energy can be understood in terms of the combination and competition between the elastic and electronic ***,the electronic binding energy follows a similar trend to the total binding energy and plays a major role in the solute–vacancy interactions.

关键词： first-principles calculations solute-vacancy binding aluminum alloys

Characteristics of convection and overshooting in RGB and AGB stars

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Research in Astronomy and Astrophysics 2011年第10期11卷 1143-1157页

作者： xiang-jun Lai Yan Li National Astronomical Observatories / Yunnan Observatory Chinese Academy of Sciences Kunming 650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy ofSciences Kunming 650011 China Graduate University of Chinese Academy of Sciences Beijing 100049 China.

Based on the turbulent convection model （TCM） of Li ＆ Yang, we have studied the characteristics of turbulent convection in the envelopes of 2 and 5M⊙ stars at the red giant branch and asymptotic giant branch phases. The TCM has been successfully applied over the entire convective envelopes, including the convective unstable zone and the overshooting regions. We find that the convective motions become progressively stronger when the stellar models are located farther up along the Hayashi line. In the convective unstable zone, we find that the turbulent correlations are proportional to functions of a common factor （V - V^d）T, which explains similar distributions in those correlations. For the TCM we find that if the obtained stellar temperature structure is close to that of the mixing length theory （MLT）, the convective motion will have a much larger velocity and thus be more violent. However, if the turbulent velocity is adjusted to be close to that of the MLT, the superadiabatic convection zone would be much more extended inward, which would lead to a lower effective temperature of the stellar model. For the overshooting distance, we find that the e-folding lengths of the turbulent kinetic energy k in both the top and bottom overshooting regions decrease as the stellar model is progressively located farther up along the Hayashi line, but both the extents of the decrease are not obvious. The overshooting distances of the turbulent correlation /u＇rT＂ are almost the same for the different stellar models with the same set of TCM parameters. For the decay modes of the kinetic energy k, we find that they are very similar for different stellar models based on the same set of TCM parameters, and there is a nearly linear relationship between lg k and In P for different stellar models. When Cs or α increases while the other parameters are fixed, the obtained linearly decaying distance will become longer.

关键词： stars RGB and AGB -- convection of stars -- turbulent convection model convective overshooting

Low Overhead and Fast Reaction Adaptive Clocking System for Voltage Droop Tolerance

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Chinese Journal of Electronics 2019年第3期28卷 503-507页

作者： shanG Xinchao shan Weiwei xiang Yiming WAN Liang FAN Ao National ASIC System Engineering Research Center Southeast University

Variation in on-chip power supply continues to be a major challenge to limit circuit performance. To mitigate the impact of high-frequency voltage droop, a novel all-digital adaptive clock system is proposed. The adaptive clock system is composed of a droop detector and an adaptive clock generator, which directly stretch the clock period when the circuit suffers from the supply voltage droop. The droop detector circuit detects the VDD droop and the digital adaptive clock generator circuit selects the stretched clock to prevent timing-margin failures. The response time for droop detection and clock stretch can be as fast as one cycle. The whole scheme is used on a test circuit under SMIC 40 nm CMOS process with a layout area of 900 um*1100 um. Postlayout simulation results demonstrate power reductions are 7% at 1.1 V and 15% at 0.7 V for a 10% VDD droop,respectively.

关键词： Voltage droop Adaptive clock system Droop detector Adaptive clock generator

Microscopic study of higher-order deformation effects on the ground states of superheavy nuclei around^(270)Hs

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Chinese Physics C 2022年第2期46卷 140-148页

作者： Xiao-Qian Wang xiang-xiang Sun shan-Gui Zhou CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of ScienceBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China

We investigate the effects of higher-order deformations β_(λ)(λ=4,6,8,and 10)on the ground state prop-erties of superheavy nuclei(SHN)near the doubly magic deformed nucleus ^(270)Hs using the multidimensionally-con-strained relativistic mean-field(MDC-RMF)model with five effective interactions:PC-PK1,PK1,NL3^(+),DD-ME2,and *** doubly magic properties of ^(270)Hs include large energy gaps at N=162 and Z=108 in the single-particle *** investigating the binding energies and single-particle levels of ^(270)Hs in the multidimensional de-formation space,we find that,among these higher-order deformations,the deformationβ6 has the greatest impact onthe binding energy and influences the shell gaps *** conclusions hold for other SHN near ^(270)*** calculations demonstrate that the deformation β_(6) must be considered when studying SHN using MDC-RMF.

关键词： density functional theory superheavy nuclei deformation effects