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Synthesis of Fe_3O_4 nanoparticles by wet milling iron powder in a planetary ball mill

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China Particuology 2007年第5期5卷 357-358页

作者： ding chen Song Ni Zhenhua chen Institute for Materials Research Hunan University Changsha 410082 China

Fe3O4 nanoparticles with sizes ranging from 30 to 80 nm were synthesized by wet milling iron powders in a planetary ball mill. The phase composition and the morphologies of the as-synthesized products were measured by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. Nanosized Fe3O4 particles were prepared by wet milling metallic iron powder （-200 mesh, 99%） in a planetary ball mill equipped with stainless steel vials using iron balls under distilled water with a ball-to-powder mass ratio of 50：1 and at a rotation speed of 300 rpm. The use of the iron balls in this method played a key role in Fe3O4 formation. The present technique is simple and the process is easy to carry out.

关键词： Fe3O4 Wet milling Planetary ball mill

Optimization of the process for preparing Al-doped ZnO thin films by sol-gel method

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Science China(Technological Sciences) 2009年第1期52卷 88-94页

作者： chen JianLin chen ding chen ZhenHua College of Materials Science and Engineering Hunan UniversityChangsha 410082China

Transparent and conducting Al-doped ZnO thin films with c-axis-preferred orientation were prepared on glass substrate via sol-gel route. The physical and chemical changes during thermal treatment were analyzed by TG-DSC spectra and the crystallization quality was characterized by XRD patterns. The optimized preheating and post-heating temperatures were determined at ～420°C and ～530°C, respectively. From thermodynamic and kinetics views, we investigated the mechanism of orientation growth with (002) plane parallel to the substrates. The surface morphologies of the films, post-heated at 420°C, 450°C, 530°C and 550°C, respectively, were observed by SEM micrographs. The film post-heated at 530°C shows a homogenous dense microstructure and exhibits the minimum sheet resistance of 140 Ω/Sq. The visible optical transmittance of all the films is beyond 90%. In addition, the annealing treatment in vacuum can contribute greatly to the electrical conductivity.

关键词： transparent conducting oxide sol-gel method zinc oxide aluminum thin films

Approximate and numerical analysis of nonlinear forced vibration of axially moving viscoelastic beams

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Acta Mechanica Sinica 2011年第3期27卷 426-437页

作者： Hu ding Li-Qun chen Shanghai Institute of Applied Mathematics and Mechanics Shanghai University 200072 Shanghai China Department of Mechanics Shanghai University 200436 Shanghai China

Steady-state periodical response is investigated for an axially moving viscoelastic beam with hybrid supports via approximate analysis with numerical confirmation. It is assumed that the excitation is spatially uniform and temporally harmonic. The transverse motion of axially moving beams is governed by a nonlinear partial-differential equation and a nonlinear integro-partial-differential equation. The material time derivative is used in the viscoelastic constitutive relation. The method of multiple scales is applied to the governing equations to investigate primary resonances under general boundary conditions. It is demonstrated that the mode uninvolved in the resonance has no effect on the steady-state response. Numerical examples are presented to demonstrate the effects of the boundary constraint stiffness on the amplitude and the stability of the steady-state response. The results derived for two governing equations are qualitatively the same,but quantitatively different. The differential quadrature schemes are developed to verify those results via the method of multiple scales.

关键词： Axially moving beam. Nonlinearity . Mate-rial time derivative . Method of multiple scales. Differentialquadrature method

An improved interval model updating method via adaptive Kriging models

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Applied Mathematics and Mechanics(English Edition) 2024年第3期45卷 497-514页

作者： Sha WEI Yifeng chen Hu ding Liqun chen Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Frontier Science Center of MechanoinformaticsShanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China Shanghai Institute of Aircraft Mechanics and Control Shanghai 200092China

Interval model updating(IMU)methods have been widely used in uncertain model updating due to their low requirements for sample ***,the surrogate model in IMU methods mostly adopts the one-time construction *** makes the accuracy of the surrogate model highly dependent on the experience of users and affects the accuracy of IMU ***,an improved IMU method via the adaptive Kriging models is *** method transforms the objective function of the IMU problem into two deterministic global optimization problems about the upper bound and the interval diameter through universal grey *** optimization problems are addressed through the adaptive Kriging models and the particle swarm optimization(PSO)method to quantify the uncertain parameters,and the IMU is *** the construction of these adaptive Kriging models,the sample space is gridded according to sensitivity *** sampling is then performed in key subspaces based on the maximum mean square error(MMSE)*** interval division coefficient and random sampling coefficient are adaptively adjusted without human interference until the model meets accuracy *** effectiveness of the proposed method is demonstrated by a numerical example of a three-degree-of-freedom mass-spring system and an experimental example of a butted cylindrical *** results show that the updated results of the interval model are in good agreement with the experimental results.

关键词： interval model updating(IMU) non-probabilistic uncertainty adaptive Kriging model surrogate model grey number

An efficient method for collision-free and jerk-constrained trajectory generation with sparse desired way-points for a flying robot

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Science China(Technological Sciences) 2021年第8期64卷 1719-1731页

作者： chen YongXue DONG Wei ding Ye State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai200240China

In this paper,an efficient approach is developed to plan jerk-constrained smooth trajectories passing through desired way-points with allowable accuracy for an autonomous ***,based on the B-spline model,we introduce the sequential convex programming(SCP)into the flexible path planning method to satisfy the way-points *** approximating the quadrotor and obstacles as spheres and directed planes,the length-optimal and collision-free path planning problem is formulated as a nonconvex optimization problem and solved by *** initial C^(3) continuous path curve for optimization is constructed efficiently based on a proposed strategy of generating new way-points near the obstacles without the need to calculate the embedding distance between the curve and the *** this basis,the time-optimal speed planning problem is addressed in two *** the first step,the forward-backward approach is introduced to solve the problem under the chord error,velocity,and acceleration constraints by changing the variables and deforming the *** by relaxing the constraints appropriately,the problem under jerk constraints is formulated into a linear programming(LP)*** feasibility of the proposed approach is verified through simulations and an indoor navigation *** proposed approach can generate a C^(3) continuous collision-free trajectory that passes through the sparse desired way-points with allowable accuracy while guaranteeing the chord error,velocity,acceleration,and jerk *** the number of sample points is 3000,the proposed speed planning method reduces the calculation time by 40%compared to an existing method.

关键词： collision avoidance speed optimization motion planning sequential convex programming quadrotor

Optimal Policy for Remanufacturing Firms with Carbon Options under Service Requirements

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Journal of Systems Science and Systems Engineering 2022年第1期31卷 34-63页

作者： Junfei ding Weida chen Shuaishuai Fu School of Economics and Management Southeast UniversityNanjing 211189China

This paper studies the procurement management of carbon financial instruments and the production decisions for an emission-dependent remanufacturing firm under service *** the presence of demand uncertainty,carbon emission options are introduced to hedge risks for the firm who purchases carbon financial instruments under a cap-flexible emission trading scheme(ETS)and then conducts *** develop three optimization models to determine the optimal remanufacturing quantity(procurement quantity of carbon financial instruments)maximizing the firm's expected profit under three contracts:a pure wholesale price contract,a pure carbon option contract,and a portfolio *** analyses and comparisons of optimal solutions,we demonstrate the values of introducing carbon options and committing to service levels for the *** with the other two pure contracts,the portfolio contract makes the firm better ***,high service requirements may lead to a profit loss to the *** generalize to the cases when the yield rate is dependent on the quality of used products,when the yield is stochastic,and when carbon price performs *** of these extensions illuminates how the variability of used product quality,yield rate and carbon price influences the firm's performances.

关键词： Carbon options remanufacturing service requirements emission trading scheme

Bending vibration control of pipes conveying fluids by nonlinear torsional absorbers at the boundary

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Science China(Technological Sciences) 2021年第8期64卷 1690-1704页

作者： MAO XiaoYe ding Hu chen LiQun Shanghai Institute of Applied Mathematics and Mechanics Shanghai UniversityShanghai200072China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai UniversityShanghai200072China School of Mechanics and Engineering Science Shanghai UniversityShanghai200444China

A nonlinear torsional absorber,which can overcome the influence of the fluid velocity on the natural frequency,is employed at the boundary to restrain the bending vibration of a pipe for the first *** using the rotating angle at the end of the pipe,the bending vibration energy is pumped to the boundary *** nonlinearly coupled pipe-absorber governing equations are obtained by the generalized Hamilton’s ***-state responses subjected to a basement excitation are discussed by the *** to this method,the boundaries of the pipe are treated as the generalized governing *** this way,those nonlinearities and time-dependent terms in the boundary are involved in the response completely.A direct simulation method,called the differential quadrature element method(DQEM),is used to verify these analytical *** investigation indicates that the nonlinear boundary absorber owns two outstanding *** first one is that the natural characters remain the same and the absorber can capture the resonance of the pipe *** second one is that the absorber works at all natural ***,by using the nonlinear damping,the absorber will not worsen the weak vibration in the non-resonance *** parameters of the absorber are investigated to optimize the efficiency in *** result finds that good efficiency can be achieved with a tiny ***,the efficiency becomes better as the damping *** the help of these investigations,the work provides a new strategy to protect pipes conveying fluids from being destroyed by the vibration.

关键词： pipes conveying fluid boundary control nonlinear torsional absorber boundary nonlinear energy sink nonlinear damping

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Numerical study on turbulent mixed convection in a vertical plane channel using hybrid RANS/LES and LES models

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Chinese Journal of Chemical Engineering 2020年第1期28卷 1-8页

作者： Puxian ding Shuangfeng Wang Kai chen Key Laboratory of Enhanced Heat Transfer and Energy Conservation of the Ministry of Education School of Chemistry and Chemical EngineeringSouth China University of TechnologyGuangzhou 510640China

Two Delayed-Detached Eddy Simulation(DDES) models, and a Large-Eddy Simulation(LES) model are used to investigate the turbulent flows and mixed convection between a hot plate and a cold plate via the software FLUENT. The two DDES models include Production-limited DDES(PL-DDES) and Improved DDES(IDDES) *** Wall-Adapting Local Eddy-Viscosity(WALE) model is the used LES model. The numerical computations are performed at Reynolds number Reb= 4494 and different Richardson numbers Ri = 0.025, 0.048, 0.1. The comparing data is from the Direct Numerical Simulation(DNS) at Reb= 4494 and Ri = 0.048. The comparison reveals that the two DDES models have better performance in predicting time-averaged parameters than the WALE model in the aiding flow. The best predicted time-averaged results are obtained by the PL-DDES model in the opposing flow. Furthermore, the results of different Ri obtained by the PL-DDES model agree well with the DNS data.

关键词： Turbulent mixed convection Hybrid RANS/LES model PL-DDES model WALE model Vertical plane channel

The influence of physiological environment on the targeting effect of aptamer-guided gold nanoparticles

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Nano Research 2019年第1期12卷 129-135页

作者： ding ding Yinling Zhang Edward A.Sykes Long chen Zhuo chen Weihong Tan Molecular Science and Biomedicine Laboratory(MBL) State Key Laboratory of Chemo/Bio-Sensing and ChemometricsCollege of Chemistry and Chemical Engineering and College of Life SciencesHunan UniversityChangsha 410082China School of Medicine Queens University81 Barrie StreetKingstonONK7L 3N6Canada Faculty of Science and Technology University of MacaoAvenida da UniversidadeMacao Taipa 999078China Department of Chemistry Departments of Physiology and Functional GenomicsCenter far Research at the Bio/Nano InterfaceUF Health Cancer CenterUF Genetics Institute and McKnight Brain InstituteUniversity of FloridaGainesvilleFlorida 32611USA Institute of Molecular Medicine Renji HospitalShanghai Jiao Tong University School of MedicineShanghai Jiao Tong UniversityShanghai 200240China

Aptamer guided nano medicine shows great promise in targeted cancer *** the loss of targeting capacity duri ng in vivo or clinical trials has largely hindered its popularity and there are no systematic studies to elucidate the ***,we investigated such loss of targeting capacity by examining how the physiological milieu affected targeting *** functionalized gold nanoparticle(AuNP)was chosen as the model and exposed to human blood serum that is used to mimic physiological *** light scattering(DLS),flow cytometry and label-free liquid chromatography tan dem mass spectrometry(LC-MS/MS)were employed to determi ne variations of NPs'surface chemistry and biological identities changes after serum *** showed that the targeting ability loss was caused by protein corona blocking,replacement and enzymatic cleavage of surface aptamer targeting ***,the aggregation issue is critical for the smaller *** of the protein corona profile indicated the accumulation of immune-related proteins on the surface of aptamer-conjugated NPs,which could induce immune response,resulting in rapid clearanee of NPs.

关键词： targeting effect aptamer nanomedicine physiological environment