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Constructing mild expanded graphite microspheres by pressurized oxidation combined microwave treatment for enhanced lithium storage

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Rare Metals 2021年第4期40卷 837-847页

作者： Can-liang Ma Zhen-Hui Hu Ning-jing Song Yun Zhao Yan-Zhen Liu Hui-qi Wang Key Laboratory of Materials for Energy Conversion and Storage of Shanxi Province Institute of Molecular ScienceShanxi UniversityTaiyuan 030006China College of Chemistry and Chemical Engineering Jinzhong UniversityJinzhong 030619China CAS Key Laboratory of Carbon Materials Institute of Coal ChemistryChinese Academy of SciencesTaiyuan 030001China School of Energy and Power Engineering School of Material Science and EngineeringNorth University of ChinaTaiyuan 030051China

The modified graphite anode materials have some prominent advantages over other anode materials in the industrial applications.A novel simple and gentle method is proposed to synthesize the mild expanded graphite microspheres(MEGMs) from flake graphite spheres through a combined modified pressurized oxidation combined with the microwave *** microstructural results demonstrate that moderately expanded MEGMs with an expansion volume between 4 and 10 ml·g^(-1)exhibit a highly microporous structure with an enlarged interlayer spacing,a decreased microcrystalline size,as well as an increased number of functional groups on the surface,resulting in the increased storage sites and spaces for lithium ions and the enhanced diffusion rate of lithium *** used as the anode material for lithium-ion batteries,the MEGM-T75t30 obtained by oxidation treatment at 75℃ for 30 min followed by microwave irradiation for expansion displays a high reversible capacity of 446.7 mAh·g^(-1) at 100 mA·g^(-1) after 100 cycles and excellent rate performance(330 and 116 mAh·g^(-1) at 800 and 3200 mA·g^(-1),respectively).Therefore,the MEGMs prepared by this convenient and mild method show excellent electrochemical properties and good application potential.

关键词： Pressurized oxidation Microwave treatment Mild expanded graphite microspheres Microstructure Graphitic anode material Lithium-ion battery

Dynamic stress concentration of an elliptical cavity in a semi-elliptical hill under SH-waves

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Earthquake Engineering and Engineering Vibration 2021年第2期20卷 347-359页

作者： qi Hui Chu Fuqing Guo jing College of Aerospace and Civil Engineering Harbin Engineering UniversityHarbin 150001China

The method of wave-function expansion in elliptical coordinates,elliptical cosine half-range expansion and Mathieu function were applied to obtain an exact analytical solution of the dynamic stress concentration factor(DSCF)around an elliptical cavity in a shallow,semi-elliptical *** infinite system of simultaneous linear equations for solving this problem was established by substituting the wave expression obtained by the Mathieu function including the standing wave expression of elliptical lining given herein into the boundary condition obtained by the region-matching *** finite equations system with unknown coefficients obtained by truncation were solved numerically,and the results in the case of an ellipse degenerating into a circle were compared with previous results to verify the accuracy of the *** effects of different aspect ratios,incident wave angles and aperture ratios on the dynamic stress concentration around the elliptical cavity were *** numerical results,when the elliptical hill was changed into a circular one,were analyzed and compared in *** engineering,this model can be regarded as a semi-cylindrical hill with an elliptical cylindrical unlined tunnel under the action of SH waves,and the results are significant in aseismic design.

关键词： SH waves dynamic stress concentration factor(DSCF) elliptical coordinate Mathieu function

Adaptive leader–follower formation control for swarms of unmanned aerial vehicles with motion constraints and unknown disturbances

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Chinese Journal of Aeronautics 2020年第11期33卷 2972-2988页

作者： Yueqian liang qi DONG Yanjie ZHAO China Academy of Electronics and Information Technology Beijing 100041China

In this paper,the 3D leader–follower formation control problem,which focuses on swarms of fixed-wing Unmanned Aerial Vehicles(UAVs)with motion constraints and disturbances,has been *** formation errors of the follower UAVs have been transformed into the Frenet-Serret *** control laws satisfying five motion constraints(i.e.,linear velocity,linear acceleration,heading rate,climb rate and climb angle)have been *** convergence of the control laws has been discussed via the Lyapunov stability *** addition,to address the unknown disturbances,an adaptive disturbance observer is ***,formation control laws involving estimated disturbances are presented as *** collision avoidance between UAVs is achieved with the artificial potential *** results obtained using four scenarios verify the effectiveness of the proposed method in situations with constant disturbances and varying disturbances,as well as without disturbances.

关键词： Constraint handling Disturbance rejection Formation flying Leader–follower method Swarm

Glucose-conjugated chitosan nanoparticles for targeted drug delivery and their specific interaction with tumor cells

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Frontiers of Materials Science 2014年第4期8卷 363-372页

作者： jing LI Fang-Kui MA qi-Feng DANG Xing-Guo liang Xi-Guang CHEN College of Food Science and Engineering Ocean University of China Qingdao 266003 China Freshwater Fisheries Research Institute of Shandong Province Jinan 250013 China College of Marine Life Science Ocean University of China Qingdao 266003 China

A novel targeted drug delivery system, glucose-conjugated chitosan nanoparticles （GCNPs）, was developed for specific recognition and interaction with glucose transporters （Gluts） over-expressed by tumor cells. GC was synthesized by using succinic acid as a linker between glucosamine and chitosan （CS）, and successful synthesis was confirmed by NMR and elemental analysis. GCNPs were prepared by ionic crosslinking method, and characterized in terms of morphology, size, and zeta potential. The optimally prepared nanoparticles showed spherical shapes with an average particle size of （187.9 ± 3.8） nm and a zeta potential of （-15.43 ± 0.31） mV. The GCNPs showed negligible cytotoxicity to mouse embryo fibroblast and 4T1 cells. Doxorubicin （DOX） could be efficiently entrapped into GCNPs, with a loading capacity and encapsulation efficiency of 20.11% and 64.81%, respectively. DOX-Ioaded nanoparticles exhibited sustained-release behavior in phosphate buffered saline （pH 7.4）. In vitro cellular uptake studies showed that the GCNPs had better endocytosis ability than CSNPs, and the antitumor activity of DOX/GCNPs was 4-5 times effectiveness in 4T1 cell killing than that of DOX/CSNPs. All the results demonstrate that nanoparticles decorated with glucose have specific interactions with cancer cells via the recognition between glucose and Gluts. Therefore, Gluts-targeted GCNPs may be promising delivery agents in cancer therapies.

关键词： drug delivery target nanoparticle glucose transporter (Glut) chitosan(CS)

Nonlinear Performance of MEMS Vibratory Ring Gyroscope

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Acta Mechanica Solida Sinica 2021年第1期34卷 65-78页

作者： Feng liang Dong-Dong liang Ying-jing qia College of Mechanical Engineering Yangzhou UniversityYangzhou225127China Beijing Key Laboratory of Nonlinear Vibrations and Strength of Mechanical Engineering College of Mechanical Engineering and Applied ElectronicsBeijing University of TechnologyBeijing100124China

Micro-electro-mechanical system(MEMS)gyroscopes are an important sort of inertial sensor for identifying parameters of spinning structures,such as the spinning speed and angular deviation,based on the Coriolis *** this paper,the nonlinear mechanism of MEMS vibratory ring gyroscopes is analyzed by applying a fully coupled nonlinear model,in which the gyroscopic coupling and geometrically and structurally nonlinear couplings are all taken into *** coupled differential equations governing the drive and sense motions are established via the Lagrangian *** simulation is conducted,and the key nonlinear components and energy transfer behaviors between the drive and sense modes are *** is revealed that the cubic rigidity nonlinearity is another significant factor leading to the coupling between the drive and sense modes other than the gyroscopic *** analysis is also carried out by using the method of multiple *** nonlinear frequency-amplitude responses of the drive and sense vibrations are obtained,and comprehensive parametric studies are *** significant effects of system damping,excitation amplitude,drive amplitude and spinning speed on the responses are discussed,which will facilitate to improve the nonlinear performance and sensitivity of the gyroscope.

关键词： MEMS vibratory ring gyroscope Nonlinear performance Drive mode Sense mode Method of multiple scales

Rollover prevention control for a four in-wheel motors drive electric vehicle on an uneven road

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Science China(Technological Sciences) 2018年第6期61卷 934-948页

作者： ZHANG LiPeng LI liang qi BingNan School of Vehicle and Energy Yanshan University Qinhuangdao 066004 China School of Electrical Engineering Yanshan University Qinhuangdao 066004 China

When a four in-wheel motors drive electric vehicle with a specific wheels mass is running on an uneven road and transient steering occurs in the meantime, the joint action of the large unsprung dynamic load and the centrifugal force may cause the vehicle to rollover. To avoid the above accident, a rollover prevention control method based on active distribution of the in-wheel motors driving torques is investigated. First, tile rollover evolution process of the four in-wheel motors drive electric vehicle under the described operating condition is analyzed. Next, a multiple degrees of freedom vehicle dynamics model including an uneven road tyre model is established, and the rollover warning threshold is determined according to the load transfer ratio. Then, the hypothesis of the effects of unsprung mass on the vehicle roll stability on a plat road and on an uneven road is verified respectively. Finally, a rollover prevention controller is designed based on the distribution of the four wheels driving torques with sliding mode control, and the control effect is verified by simulations. The conclusion shows that, once the wheels mass does not match road conditions, the large unsprung mass may play a detrimental role on the vehicle roll stability on an uneven road, which is different from the beneficial role of large unsprung mass on the vehicle roll stability on a plat road. With the aforementioned rollover prevention controller, the vehicle rollover, which is caused by the coupling effect between large unsprung dynamic load and suspension potential energy on an uneven road, can be avoided effectively.

关键词： electric vehicle in-wheel motor drive roll stability uneven road

Study on UV, IR and NMR Spectra of Double Hydrogen-bonded Complexes

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Chinese Journal of Structural Chemistry 2006年第2期25卷 143-148页

作者： ZHU liang-liang TENG qi-Wen WU Shi Department of Chemistry Zhejiang University Hangzhou 310027 China

AM 1, PM3 and DPT methods were used to study on the hydrogen-bonded dimer of melamine and [ 1,3] dioxane-2,4,6-trione. The electronic spectra, IR and NMR spectra of some complexes were calculated with INDO/SCI, AM 1 and B3LYP/6-31G（d） methods, respectively. It is demonstrated that the negative stability energy is responsible for the formation of the complexes. Stabilization energies of these complexes were altered among the variations of electric property and steric effects of the monomers. HOMO-LUMO energy gaps were shrunk and the blue-shift of absorptions in the electronic spectra occurred. The vibrations of N-H bonds and chemical shifts of the protons changed with the formation of hydrogen bonds.

关键词： melamine dioxane-2,4,6-trione hydrogen bonds B3LYP

Game-theoretic spectrum sharing for cognitive radio based on the expectation of primary users

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The Journal of China Universities of Posts and Telecommunications 2010年第3期17卷 6-12页

作者： MA liang ZHU qi Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and Telecommunications Nanjing 210003 China National Mobile Communications Research Laboratory Southeast University Nanjing 210003 China

Cognitive radio is a new intelligent wireless communication technique for remedying the shortage of spectrum resource in recent years. Secondary users have to pay when they share available spectrum with primary users while price is an important factor in the spectrum allocation. Based on the game theory, an improved pricing function is proposed by considering the expectation of primary users. In this article, expectation represents the positivity of sharing spectrum with primary users. By introducing the positivity, price not only becomes different for different secondary users, but also can be adjusted according to the positivity. It is proved that the Nash Equilibrium of the new utility function exists. The simulation results show that spectrum sharing can not only be determined by the channel quality of secondary users, but also can be adapted according to the expectation of primary users. Besides, the proposed algorithm improves the fairness of sharing.

关键词： cognitive radio game theory spectrum allocation pricing function

Empirical Analysis on Urbanization Patterns in Zhejiang Province Based on Spatial Economy and GIS

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Chinese Geographical Science 2006年第3期16卷 193-198页

作者： GE Ying liang qi College of Civil Engineering Hohai University Nanjing 210098 China School of Business Nanjing University Nanjing 210093 China

Regional core cities are the growth poles for regional economic development, thus the issue about efficient urbanization pattern has always become a hot spot among researchers and policy makers. The Spatial Economy can be employed to improve it. Nevertheless, there actually exists an obvious gap between its theoretical models and the empirical simulation. To do so, this paper modifies the measurement of initial geographical advantages Stelder gave, and implements the empirical analyses of urban distribution in Zhejiang during the period of 1980-1990 by means of computer simulations in GIS environment. There are several interesting results achieved in this process. Firstly, given the values of parameters （transport cost is r, substitution elasticity of manufacturing sector p, and income share of spending on manufacture δ）, initial geographical advantages have the different impacts on urban systems, namely, urban locations, numbers and sizes over time across space. Secondly, the cities were distributed without any overlay in geographical space, which makes the patterns of urbanization generate the largest possible economic efficiencies. Thirdly, the urban systems-the location, number and size of Cities-from the simulation of the study area are suitable for the actual social and economic situations in the real world during the testing periods. Such results may have substantial implications for the policy how to choose the way of urbanization in a region.

关键词： urbanization pattern Spatial Economy empirical analysis GIS technique initial geographical advantage Zhejiang Province