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Theoretical Studies on Photoionization Cross Sections of Solid Gold

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Communications in Theoretical Physics 2005年第1期43卷 159-164页

作者： MAXiao-guang SUNWei-guo CHENGYan-Song InstituteofAtomicandMolecularPhysics SichuanUniversityChengdu610065China

Accurate expression for photoabsorption (photoionization) cross sections of high density system proposed recently is used to study the photoionization of solid gold. The results show that the present theoretical photoianization cross sections have good agreement both in structure and in magnitude with the experimental results of gold crystal. The studies also indicate that both the real part epsilon' and the imaginary part epsilon' of the complex dielectric constant epsilon and the dielectric influence function of a nonideal system have rich structures in low energy side with a range about 50 eV, and suggest that the influence of particle interactions of surrounding particles with the photoionized particle on the photoionization cross sections can be easily investigated using the dielectric influence function. The electron overlap effects are suggested to be implemented in the future studies to improve the accuracy of theoretical photoionization cross sections of a solid system.

关键词： photoionization cross section solid gold dielectric influence function

A Note on the Existence of Positive Solutions for a Fourth-Order Semilinear Elliptic System

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Acta Mathematica Sinica,English Series 2010年第7期26卷 1263-1276页

作者： Yu Xia guo guang Zhong CHEN Department of Mathematics Tsinghua University Beijing 100084 P. R. China

In this note, we prove the existence of positive solutions to a class of biharmonical systems. Our main ingredients are proving a Liouville type result for biharmonical system in R＋^N via the method of moving plane combined with integral inequality, and establishing a prior estimates for positive solutions of the system via the blowing-up method.

关键词： topological degree theory a prior estimate fourth-order system Liouville theorem

Highly Improved Creep Resistance in Polypropylene Through Thermally Reduced Graphene Oxide and Its Creep Lifetime Prediction

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Chinese Journal of Polymer Science 2024年第2期42卷 256-266,I0010页

作者： Can-Can Zhang Jun-Long Yang Ya-Jiang Huang guang-xian Li College of Polymer Science and Engineering State Key Laboratory of Polymer Materials Engineering of ChinaSichuan UniversityChengdu610065China

Polypropylene(PP) exhibits suboptimal creep resistance due to the presence of methyl groups on its main chain, leading to irregular chain segment distribution, diminished inter-chain interaction, and crystallinity. This structural feature causes chain slippage in PP under stress,significantly constraining its service lifetime. In this study, thermally reduced graphene oxide(TrGO) nanosheets were incorporated into the PP matrix, yielding a nanocomposite with exceptional creep resistance performance. Results demonstrated that at a stress of 25 MPa, a 2.0 wt% TrGO content could enhance the creep failure lifetime of PP by 21.5 times compared to neat PP. Rheology, transmission electron microscopy(TEM),and scanning electron microscopy(SEM) characterization techniques were employed to analyze the mechanism of TrGO's influence on PP's creep behavior. It was observed that when TrGO content exceeded 1.0 wt%, an effective particle network structure formed within the PP matrix. This homogeneously dispersed TrGO-formed particle network structure restricted the migration and rearrangement of PP molecular chains, enabling prolonged stress resistance without structural failure. By combining the time-strain superposition method with the critical failure strain as a criterion, generalized creep compliance curves for PP and its composites were established, facilitating the prediction of material creep failure lifetimes, with a strong agreement between experimental and predicted lifetime values. This research proposes a novel strategy aimed at developing polypropylene materials and products with enhanced long-term stability and durability, thus extending service life, reducing failure risk, and broadening their potential across various application domains.

关键词： Thermally reduced graphene oxide Polypropylene Creep failure and lifetime prediction

Novel mechanism for the modification of Al_2O_3-based inclusions in ultra-low carbon Al-killed steel considering the effects of magnesium and calcium

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International Journal of Minerals,Metallurgy and Materials 2018年第3期25卷 280-287页

作者： Jing guo Shu-sen Cheng Han-jie guo Ya-guang Mei School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing Key Laboratory of Special Melting and Reparation of High-end Metal Materials University of Science and Technology Beijing

Many researchers have explored the inclusion modification mechanism to improve non-metallic inclusion modifications in steelmaking. In this study, two types of industrial trials on inclusion modifications in liquid steel were conducted using ultra-low-carbon Al-killed steel with different Mg and Ca contents to verify the effects of Ca and Mg contents on the modification mechanism of Al_2O_3-based inclusions during secondary refining. The results showed that Al_2O_3-based inclusions can be modified into liquid calcium aluminate or a multi-component inclusion with the addition of a suitable amount of Ca. In addition, [Mg] in liquid steel can further reduce CaO in liquid calcium aluminate to drive its evolution into CaO–MgO–Al_2O_3 multi-component inclusions. Thermodynamic analysis confirmed that the reaction between [Mg] and CaO in liquid calcium aluminate occurs when the MgO content of liquid calcium aluminate is less than 3 wt% and the temperature is higher than 1843 K.

关键词： inclusions mechanism modification ultra-low carbon Al-killed steel calcium treatment magnesium content

Wearing prediction of stellite alloys based on opposite degree algorithm

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Rare Metals 2015年第2期34卷 125-132页

作者： Xiao-guang Yue guang Zhang Qu Wu Fei Li xian-Feng Chen Gao-Feng Ren Mei Li School of Resources and Environmental Engineering Wuhan University of Technology School of Materials Science and Engineering Shanghai University

In order to predict the wearing of stellite alloys, the related methods of rare metals data processing were discussed. The method of opposite degree （OD） algorithm was put forward to predict the wearing of stellite alloys. OD algorithm is based on prior numerical data, posterior numerical data and the opposite degree between numerical forecast data. To compare the performance of predicted results based on different algorithms, the back propagation （BP） and radial basis function （RBF） neural network methods were introduced. Predicted results show that the relative error of OD algorithm is smaller than those of BP and RBF neural network methods. OD algorithm is an effective method to predict the wearing of stellite alloys and it can be applied in practice.

关键词： Opposite degree algorithm Stellite alloyswearing Back propagation neural network Radial basisfunction neural network

Area Spectra of Schwarzschild-Anti de Sitter Black Holes from Highly Real Quasinormal Modes

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Chinese Physics Letters 2011年第10期28卷 9-12页

作者： guo guang-Hai DING Xia School of Mathematics and Physics Qingdao University of Science and TechnologyQingdao 266061

Motivated by the new physical interpretation of quasinormal modes proposed by Maggiore [Phys. Rev. Lett. 100 (2008) 141301], we investigate the quantization of large Schwarzschild-Anti de Sitter black holes in even-dimensional spacetimes, from the interesting highly real quasinormal modes found recently. Following Maggiore's treatment and Kunstatter's method, we derive the area and entropy spectra of the black holes. It is found that the results from both approaches are in full consistency. This implies that one can quantize a black hole via different asymptotic quasinormal modes besides the high damping ones that are usually adopted in the literature. Furthermore, we find that the area and entropy spectra are equidistant and independent of the cosmological constant. However, the spacings depend on the black hole dimension.

关键词： Schwarzschild black entropy

High-temperature Thermo-oxidative Aging of Vulcanized Natural Rubber Nanocomposites:Evolution of Microstructure and Mechanical Properties

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Chinese Journal of Polymer Science 2023年第8期41卷 1287-1297,I0010页

作者： Zhou-xian Li Yi-Ran Kong xiang-Fei Chen Ya-Jiang Huang Ya-Dong Lv guang-xian Li College of polymer science and engineering State key laboratory of polymer materials engineering of ChinaSichuan UniversityChengdu 610065China

The aging of natural rubber(NR)at high temperatures will seriously affect its service lifetime in many key *** the present work,the changes in microstructure and mechanical properties of semi-efficient vulcanized NR/carbon black(CB)vulcanizates during thermooxidative aging at high temperatures(150-200℃)and a moderate temperature(95℃)were *** high temperatures,a two-stage aging behavior,which was characteristic of a first rapid decline and then a continuous rise in the crosslinking density(ve),was identified and was found to be closely related to the depletion behavior of *** surface cracking behavior observed in the second stage of high-temperature aging was discussed in terms of the grafting reaction of macromolecular radicals on CB particles and thermal *** contrast,the aging of NR at moderate temperatures was much mild,which featured a continuous increase in ve and an oxidation mechanism dominated by peroxy radicals attacking double *** general,the mechanical properties of NR vulcanizates during high-temperature aging depended on the competition effects of structural evolution in the crosslinked network and oxidation-induced chain scission.

关键词： Natural rubber nanocomposites High-temperature Thermo-oxidative aging

Precipitation behavior of titanium nitride on a primary inclusion particle during solidification of bearing steel

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Journal of Iron and Steel Research International 2017年第7期24卷 685-690页

作者： Liang Yang Bryan A. Webler guo-guang Cheng State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Center for Iron and Steelmaking Research Department of Materials Science and EngineeringCarnegie Mellon University

Titanium nitride precipitation on a primary inclusion particle during solidification of bearing steel has been tracked by varying temperature in a confocal scanning violet laser *** precipitation,an obvious growth of titanium nitride on a primary inclusion particle was observed due to the rapid solute diffusion in liquid *** onset of titanium nitride precipitation did not change with primary inclusion particle size,but the time of growth was greater for a smaller primary inclusion ***,the particle size displayed little influence on the total precipitated amount of titanium nitride on it under the same *** the later period of solidification,almost no change occurred in inclusion size,but the inclusion shape varied from circle to almost square in two-dimension,or cubic in three-dimension,to attain the equilibrium with steel.

关键词： Real time observation Titanium nitride growth Bearing steel Precipitation Solidification Inclusion

Carbothermic reduction characteristics of ludwigite and boron–iron magnetic separation

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International Journal of Minerals,Metallurgy and Materials 2018年第9期25卷 1000-1009页

作者： guang Wang Qing-guo Xue Jing-song Wang State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing

Ludwigite is a kind of complex iron ore containing boron, iron, and magnesium, and it is the most promising boron resource in China. Selective reduction of iron oxide is the key step for the comprehensive utilization of ludwigite. In the present work, the reduction mechanism of ludwigite was investigated. The thermogravimetry and differential scanning calorimetry analysis and isothermal reduction of ludwigite/coal composite pellet were performed. Ludwigite yielded a lower reduction starting temperature and a higher final reduction degree compared with the traditional iron concentrates. Higher specific surface area and more fine cracks might be the main reasons for the better reducibility of ludwigite. Reducing temperature highly affected the reaction fraction and microstructure of the reduced pellets, which are closely related to the separation degree of boron and iron. Increasing reducing temperature benefited the boron and iron magnetic separation. Optimum magnetic separation results could be obtained when the pellet was reduced at 1300°C. The separated boron-rich non-magnetic concentrate presented poor crystalline structure, and its extraction efficiency for boron reached 64.3%. The obtained experimental results can provide reference for the determination of the comprehensive utilization flow sheet of ludwigite.

关键词： complex iron ore boron resource carbothermic reduction magnetic separation