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BIFURCATION AND DYNAMICS OF THIN SLIPPING FILMS UNDER THE INFLUENCE OF INTERMOLECULAR FORCES

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Journal of Hydrodynamics 2006年第2期18卷 248-252页

作者： HU guo-hui Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China

The effects of the Born repulsive force on the stability and dynamics of ultra-thin slipping films under the influences of intermolecular forces are investigated with bifurcation theory and numerical simulation. Results show that the repulsive force has a stabilizing effect on the development of perturbations, and can suppress the rupture process induced by the van der Waals attractive force. Although slippage will enhance the growth of disturbances, it does not have influence on the linear cutoff wave number and the final shape of the film thickness as time approaches to infinity.

关键词： ultra-thin film dewetting Navier slip boundary condition

A Novel Total Synthesis of (±)Shikonin

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Chinese Chemical Letters 2006年第7期17卷 871-873页

作者： De Feng XU Xiao juan guo Zhao hui XU Shao Shun LI School of Pharmacy Shanghai Jiaotong University Shanghai 200030

A novel total synthesis of （±）shikonin 1 was presented. The key intermediate 6 was achieved by the formylation of 1,8：4,5-bis（methylenedioxy）naphthalene 5 with N-methylformanilide in good yield. It was first reported that the addition of prenyllithium to 2-formyl-1,8：4,5- bismethylenedioxy naphthalene 6 gave 2-（1-hydroxy-4-methylpentyl） 1,8：4,5-bis（methylenedioxy） naphthalene 8 in 45% yield and 2-（1-hydroxy-2,2-dimethyl-3-butenyl）-1,8：4,5-bis（methylenedioxy）naphthalene 9 in 48% yield. After the electrooxide deprotection of 8, （±）shikonin 1 was prepared in high yield.

关键词： (±)Shikonin total synthesis prenyllithium.

Research on the measurement of the price change of telecom services in China

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The Journal of China Universities of Posts and Telecommunications 2006年第3期13卷 110-113页

作者： ZHAO hui-juan Management Department Xi'an University of Posts and TelecommunicationsXi'an 710061 China

It is difficult to measure the total change of the telecom service price （TSP） in China due to the complexity of TSP and the diversity of telecom service. This article analyzes the relation between telecom service revenue and traffic volumes of telecom service and deduces the method of measuring the total change in tendency of telecom price, which is based on the consumer＇s actual payment for telecom services. After describing the changing trend of TSP with the time series data from 1949 to 2000, the TSP showed a continuous declining tendency during 1949～1975. In contrast, the TSP showed a rising tendency from 1976 to 1991 and a sharp declining trend after 1992. Empirical tests and actual background of telecom reform support the results.

关键词： price telecom service price revenue traffic volumes of telecom service

Multifunctional carbon materials from rugose rose for energy storage and water purification

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Frontiers of Chemical Science and Engineering 2024年第9期18卷 1-13页

作者： Peng-hui Li hui Zhou Wen-juan Wu Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources Nanjing Forestry UniversityNanjing 210037China College of Light Industry and Food Engineering Nanjing Forestry UniversityNanjing 210037China College of Chemical Engineering East China University of Science and TechnologyShanghai 200237China State Key Laboratory of Chemical Engineering Shanghai 200237China

With the advancement of social process,the resource problem is becoming more prominent,biomass materials come into being,and it is becoming more and more important to explore and prepare efficient and multifunctional biomass materials to alleviate the problems of energy storage and water *** this paper,nitrogen-doped hierarchical porous carbon materials(NRRC)were produced by one-step carbonization of withered rose as raw material and melamine as nitrogen source with KOH-activated *** resulting nitrogen-doped porous carbon material had the most abundant pores and the best microspherical graded pore structure,with a specific surface area of up to 1393 m2·g^(-1),a pore volume of 0.68 cm3·g^(-1),and a nitrogen-doped content of 5.52%.Electrochemical tests showed that the maximum specific capacitance of NRRC in the three-electrode system was 346.4 F·g^(-1)(0.5 A·g^(-1)),which was combined with favorable capacitance retention performance and cycling *** NRRC//NRRC symmetric supercapacitors were further assembled,and the maximum energy density of a single device was 23.88 Wh·kg^(-1),which still maintains excellent capacitance retention and cyclic charging/discharging *** example,the capacitance retention rate was always close to 96.27%with almost negligible capacitance loss after 10000 consecutive charge/discharge cycles(current density:10 A·g^(-1)).Regardless of the three-electrode or two-electrode system,the super capacitive performance of NRRC porous carbon materials was comparable to the electrochemical performance of many reported biomass porous carbon materials,which showed better energy storage advantages and practical application *** addition,NRRC porous carbon materials had excellent water purification *** dye adsorption test confirmed that NRRC had a high adsorption capacity(491.47 mg·g^(-1))for methylene *** undoubtedly also showed a potential and promising avenue for high value-added utilization

关键词： rose carbon adsorption electrode material electrochemical performance

Spring snow-albedo feedback from satellite observation,reanalysis and model simulations over the Northern Hemisphere

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Science China Earth Sciences 2022年第8期65卷 1463-1476页

作者： hui guo Yuting YANG State Key Laboratory of Hydroscience and Engineering Department of Hydraulic EngineeringTsinghua UniversityBeijing100084China

The snow-albedo feedback(SAF)is one of the key processes that lead to rapid temperature increases at high latitude and altitude ***,we examine the strength of SAF in the Northern Hemisphere(NH,30°-90°N)from satellite-based observation,climate reanalysis(i.e.,ERA5)and climate model projections(i.e.,CMIP5 and CMIP6).Using satellite-derived estimates as an observational reference,our results show that the strength of SAF is considerably overestimated by both climate reanalysis and climate models throughout the *** positive bias is mainly caused by a much higher month-to-month changing rate of surface albedo simulated by climate reanalysis and climate models,compared with satellite-based *** addition,we find that the strength of SAF is primarily controlled by changes in snow cover fraction(SNC)while the snow metamorphosis effect only plays a secondary role at the hemispheric scale and the regional ***,we demonstrate that there exists an emergent relationship between historical SAF and future SAF in climate model projections,which is then used to constrain modeled SAF in both CMIP5 and CMIP6 under various climate change *** constraining,the magnitude of modeled SAF is reduced to be more consistent with satellite-based estimates and the uncertainties of the modeled SAF are reduced by 10-50%for 13 sub-regions of the *** results highlight the need for improving the representation of surface albedo and snow cover fraction in climate reanalysis and models and the advantage of combining observation and model predictions such that to achieve a more realistic quantification of SAF and a better understanding of the impacts of SAF on the climate system.

关键词： Snow-albedo feedback Satellite observation Climate reanalysis Climate model Emergent constraint

Convergence of adaptive MPC for linear stochastic systems

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Science China(Information Sciences) 2023年第5期66卷 130-146页

作者： hui CHEN Lei guo Institute of Systems Science Academy of Mathematics and Systems Science (AMSS) Chinese Academy of Sciences

The convergence of an adaptive model predictive control(MPC) algorithm for discrete-time linear stochastic systems with unknown parameters is investigated in this paper. The proposed adaptive MPC is designed by solving a finite horizon constrained linear-quadratic optimal control problem of online estimated models, which are built on a recursive weighted least-squares(WLS) algorithm together with a random regularization method. By incorporating an attenuating excitation signal into adaptive MPC, the proposed adaptive MPC is shown to converge asymptotically to the ergodic MPC performance with known parameters by using the Markov chain ergodic theory.

关键词： adaptive control linear-quadratic optimal control model predictive control uncertain stochastic system weighted least-squares

Melamine/Stearic Acid Composite Nanowires and Vesicles with an Intercalated Nanostructure Prepared through NCCM Method

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Chinese Journal of Chemical Physics 2012年第6期25卷 708-712,I0004页

作者： juan guo Dao-yong Chen The State Key Laboratory of Molecular Engineering of Polymers and Department of MacromolecularScience Fudan University Shanf hai 200433 China

A solvent-non-solvent method invented in our laboratory for preparing non-covalently con- nected micelles （NCCM） was used to intercalate melamine （MA） molecules into stearic acid （SA） bilayers to form tile composite nanoparticles with an intercalated nanostructure in which a melamine bilayer is sandwiched between two stearic acid bilayers, NCCM method helps to sufficiently mix the two components in nanospace and meanwhile inhibits the strong tendency of self-crystallization of MA, leading to the intercalation. Although the nanopar- ticles have a regular inner structure, the primary MA/SA nanoparticles have an irregular morphology. Regular nanoparticles were obtained through annealing the suspension of the primary nanoparticles. Through annealing at different temperatures, the MA/SA compos- ite nanowires and vesicles with an intercalated structure were prepared respectively. It is proposed that the morphological change results from the change in the intercalated structure.

关键词： Organic intercalation system Non-covalently connected micelles method Annealing treatment

Relation among C-curve characterization diagrams

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第10期8卷 1663-1670页

作者： CAO juan WANG guo-zhao Institute of Computer Graphics and Image Processing Department of Mathematics Zhejiang University Hangzhou 310027 China

As three control points are fixed and the fourth control point varies, the planar cubic C-curve may take on a loop, a cusp, or zero to two inflection points, depending on the position of the moving point. The plane can, therefore, be partitioned into regions labelled according to the characterization of the curve when the fourth point is in each region. This partitioned plane is called a "characterization diagram". By moving one of the control points but fixing the rest, one can induce different characterization diagrams. In this paper, we investigate the relation among all different characterization diagrams of cubic C-curves based on the singularity conditions proposed by Yang and Wang (2004). We conclude that, no matter what the C-curve type is or which control point varies, the characterization diagrams can be obtained by cutting a common 3D characterization space with a corresponding plane.

关键词： Spline C-curve Characterization diagram Singularity

A new two-step variational model for multiplicative noise removal with applications to texture images

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Applied Mathematics(A Journal of Chinese Universities) 2024年第3期39卷 486-501页

作者： ZHANG Long-hui YAO Wen-juan SHI Sheng-zhu guo Zhi-chang ZHANG Da-zhi School of Mathematics Harbin Institute of TechnologyHarbin 150001China

Multiplicative noise removal problems have attracted much attention in recent *** additive noise,multiplicative noise destroys almost all information of the original image,especially for texture *** by the TV-Stokes model,we propose a new two-step variational model to denoise the texture images corrupted by multiplicative noise with a good geometry explanation in this *** the first step,we convert the multiplicative denoising problem into an additive one by the logarithm transform and propagate the isophote directions in the tangential field *** the isophote directions are constructed,an image is restored to fit the constructed directions in the second *** existence and uniqueness of the solution to the variational problems are *** these two steps,we use the gradient descent method and construct finite difference schemes to solve the ***,the augmented Lagrangian method and the fast Fourier transform are adopted to accelerate the *** results show that the proposed model can remove the multiplicative noise efficiently and protect the texture well.

关键词： multiplicative noise removal texture images total variation two-step variational method aug-mented Lagrangian method