科创中国

Due to the important role that AGC plays in strip steel production, fuzzy sliding control was attempted to be applied into mill AGC system. Moreover, in order to eliminate steady-state errors in system and improve control precision, integral control was also introduced into the sliding mode variable structure control, which means adopting fuzzy integral sliding mode control (FSMC) method to control the roll gap value to its permissive fields, thus eliminating the changeable mill gauge brought by changeable roll gap, consequently, automatic gauge control (AGC) was achieved. Simulation results show that FSMC not only exhibit strong robustness but also avoid the chattering phenomena, showing a promising application future.

Jian Mei Wang;庆学 黄;Shi Chun Yang

2005

A facile route for the preparation of core cross-linked polymeric micelles via self-complementary multiple hydrogen bonds was developed. Double hydrophilic block copolymers of poly(ethylene glycol)-b-poly(N-isopropylacrylamide) (PEG-b-PNIPAm), with 2-ureido-4[1H]-pyrimidinone (UPy) functionality throughout PNIPAm block, were synthesized via reversible addition-fragmentation chain transfer polymerization. It was found that the strong dimerization of the self-complementary quadruple hydrogen-bonding UPy groups could induce non-covalent intermolecular bonding between the copolymer chains and serve as core cross-linking of the formed micelles. The stability and thermo-responsive properties of the obtained micelles with varying UPy side-group content were investigated by dynamic light scattering, atomic force microscopy and fluorescence spectroscopy. The PNIPAm core of the cross-linked micelles exhibits reversible thermo-responsive swelling/shrinking behavior, as evident from the hydrodynamic diameter changes detected during cyclic heating-cooling tests. The thermo-responsive loading and release of pyrene molecules (as a model hydrophobic drug) demonstrate a potential application of the synthesized core cross-linked micelles in controlled drug delivery. The results indicate that multiple hydrogen-bonding interactions between UPy moieties can be maintained in a hydrophilic aqueous environment, which provides a convenient approach to stabilize the micellar structures and maintain responsive behaviors of double hydrophilic block copolymers by core cross-linking. This work provides new insights into designing stable and stimuli-responsive polymer micelles with a wide range of applications in drug delivery, diagnosis and sensing.

Jingsi Chen;Bin Yan;Xiaogang Wang;庆学 黄;Thomas Thundat;Hongbo Zeng

Polymer Chemistry

2017-5-28

A new coupling numerical algorithm has been developed to integrate Finite Difference Method (FDM) with Boundary Element Method (BEM) to analyze shear performance of oil film by iteratively solving a series of equations such as the film flow velocity and shear stress equations for contact bodies in bearing system. With consideration of the variations of viscosity and density with pressure and temperature, the effects of shear stress of oil film layers on lubrication performance of contact surfaces under different loadcases were discussed. Moreover, Germany-made Anton Paar MRD (Magnetic Rheologic Device) was used to determine the relationship between the viscosity and shear stress of lubricating oil. The conclusions were verified to be beneficial to the further study on lubricating performance of heavy contact components and to prolong their service lives.

Jianmei Wang;庆学 黄;Zhengyi Jiang;Kiet A. Tieu

2009

According to the damages of oil-film bearing taper sleeve with elastic cohesion on hot continuous strip mill in some large steel company, 3D boundary element method (BEM) for elastoplastic contact problems was used to qualitatively analyze the mechanical behaviors of sleeve and roll neck during the assembly process. The load models of sleeve without and under hydraulic force were respectively built, 3D BEM program was developed to simulate the assembly process, the deformed generating line of sleeve under hydraulic force was drawn, and the distribution of contact stress at different stage was obtained. The sleeve structure was revised on the basis of the simulation results. The conclusions could provide beneficial theoretical basis to the further technologies of prolonging bearing service life.

Pu Yu Yue;Jian Mei Wang;庆学 黄;兆建 杨

Zhongbei Daxue Xuebao (Ziran Kexue Ban)/Journal of North University of China (Natural Science Edition)

2008-10

Asphaltenes are the heaviest components in crude oil. It is generally believed that asphaltenes adsorbed at oil/water interface can form a protective layer to stabilize the water-in-oil or oil-in-water emulsions. In this work, the effects of asphaltene concentration and temperature on the dynamic interfacial tension (IFT) of oil (i.e., toluene)/water interface were systematically investigated using a pendent drop shape method. The adsorption process shows three stages as a function of adsorption time. In Regime I, the reduction kinetics of IFT is diffusion-controlled, during which asphaltenes are adsorbed to the oil/water interface spontaneously. The interfacial diffusion coefficient of asphaltenes to the oil/water interface was found to increase with increasing temperature and decreasing asphaltene concentration, which is much lower than the bulk diffusion coefficient predicated by the Stokes–Einstein equation. In Regime II, the steric hindrance arisen from the adsorbed asphaltenes at oil/water interface from Regime I tends to inhibit further adsorption of asphaltenes to the interface. In Regime III, continuous adsorption of asphaltenes to the sublayer of the interface and reconfiguration of adsorbed asphaltenes or asphaltene aggregates occur, contributing to the continuous but very slow reduction of dynamic interfacial tension. Our results provide useful insights into the adsorption kinetics and adsorption mechanism of asphaltenes at oil/water interfaces under different asphaltene concentration and temperature conditions, with implications to many related interfacial phenomena (e.g., emulsion stability) where asphaltenes are present in oil production.

Shuo Zhang;Ling Zhang;Xi Lu;Chen Shi;Tian Tang;Xiaogang Wang;庆学 黄;Hongbo Zeng

Fuel

2018-1-15

Titanium alloy TC11 rods with Φ25 mm, were rolled to that with Φ17 mm in four passes by a triangle-round-triangle-round sequence. The rod temperature drop was measured at entry temperature 950°C during continuous rolling, and the rolling forces and the roll torques were measured in the case of different area reductions at 750, 850, 950, and 1050°C. Then, the geometry shapes of deformation zone were analyzed for different passes. The mathematic model of the rolling force for Y-type mill was modified based on empirical modifications of two-roll theories. A number of experiments were also carried out to check the validity of the proposed mathematic model. The result shows that the difference between the calculated value and the experimental value is relatively minor. Therefore, this mathematic model can provide the foundation for theoretical research and engineering application of Y-type rolling process.

Meirong Shuai;庆学 黄;Jianping Qin;Yanchun Zhu

Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering

2012-6

With rollers as elastic bodies and workpieces as elastoplastic bodies, the rolling problem can be viewed as a friction elastic-plastic contact problem. With fewer assumptions in the simulation of strip-rolling process, a boundary element method (BEM) for two-dimensional elastoplastic finite strain and finite deformation analysis of contact problems with friction was presented. All the equations for contact problems, which include multi-nonlinearities, were obtained. Incremental and iterative procedures were used to find contact pressure and friction stress. Moreover, initial strain rate algorithm and work-hardening material behavior can be assumed in the plastic analysis. Several examples were presented, and the results of contact pressure and friction stress were in excellent agreement with those of analysis.

Yu gui LI;庆学 黄;Guang xian SHEN;Hong XIAO;Si qin PANG;Jian mei WANG

Journal of Iron and Steel Research International

2008-1

Highly textured Heusler alloy Mn_44.7Ni_43.5Sn_11.8 ribbons were prepared by melt spinning. The magnetoresistance (MR) properties were evaluated by the magnetic field perpendicular to the ribbon surface with the field up to 30 kOe. A large MR (about 25%) with a lower magnetic field (10 kOe) was obtained at 276 K. Due to the rapid solidification. The ribbons with a specific texture can get a large MR twice than polycrystalline alloys at the same magnetic field. The highly textured Mn-Ni-Sn melt spun ribbons may be broadly applied in magnetic memory and as temperature and magnetic sensors as well.

Fenghua Chen;庆学 黄;Zhengyi Jiang;Haicheng Xuan;Mingang Zhang;小红 许;Jingwei Zhao

Smart Materials and Structures

2016-4-13

In order to provide theoretical basis for the design of wind turbine's shrink disk, the calculating formula of contact pressure and magnitude of interference for interference fit of multi-layer cylinder has been deduced based on the displacement expression of thick-walled cylinder under uniform pressure. Two-dimensional axisymmetric model was established by using the finite element software ABAQUS with the dimensions of some type wind turbine's shrink disk, which was designed based on the calculating formula above, and the dynamically- simulated interference assembly was carried out. The results of contact pressure on the mating surfaces by both methods were discussed, and the errors between the two methods were analyzed. The results show that the results by analytical formulas agree well with those by finite element method and can provide theoretical guidance to the optimization design of wind turbine's shrink disk.

Jian Mei Wang;De Feng Tao;庆学 黄;Jian Feng Kang;Liang Tang

Gong Cheng Li Xue/Engineering Mechanics

2013-9

Based on rolling-cut shear simulation, using a kind of single-shaft and double eccentricity rolling-cut shear, which adopts a new structure of asymmetric feature and negative bias, as the calculating model by establishing motion path equation of spatial shear mechanism, comparing with the steel shear forces, link forces and horizontal link force components with or without asymmetric feature, the asymmetric formulation is deduced. Such asymmetric crank structure can decrease horizontal force component between the linkages during rolling-cut process, increase the effective drive force on links while it comes to the maximum shear force, and decrease the extrusion of blade arc on steel edge as well. Theoretical analysis and steel-shearing quality at site indicate that asymmetric and negative bias is an important and efficient way to prolong the lifetime of blade, decrease blade wear, improve shearing quality, and maintain the constant clearance between blades.

Zhibing Chu;庆学 黄;Zhiyuan Zhang;Dan Li

2011