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Segregation behavior of magnetic ions in continuous flowing solution under gradient magnetic field

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Chinese physics B 2016年第7期25卷 286-293页

作者：冀冰吴平任菡张师平 Abdul Rehman 王立 Department of physics School of Mathematics and Physics University of Science and Technology Beijing School of mechanical engineering University of Science and Technology Beijing

The research of magnetic separation starts from magnetic solid particles to nanoparticles, and in the research progress,particles become smaller gradually with the development of application of magnetic separation technology. Nevertheless,little experimental study of magnetic separation of molecules and ions under continuous flowing conditions has been reported. In this work, we designed a magnetic device and a ＂layered＂ flow channel to study the magnetic separation at the ionic level in continuous flowing solution. A segregation model was built to discuss the segregation behavior as well as the factors that may affect the separation. The magnetic force was proved to be the driving force which plays an indispensable role leading to the segregation and separation. The flow velocity has an effect on the segregation behavior of magnetic ions,which determines the separation result. On the other hand, the optimum flow velocity which makes maximum separation is related to the initial concentration of solution.

关键词： magnetic ions magnetic separation segregation enrichment

A New Process and Technology for Rapid Prototyping of A μ-Micro Motor

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Tsinghua Science and Technology 2009年第S1期14卷 149-153页

作者：郑炜郑珲廖锐 Department of mechanical and Electrical engineering School of Physics and Mechanical and Electrical Engineering Xiamen University China Telecom

A new process and technology of rapid prototyping for a μ-micro motor is presented as a nontraditional machining and an advanced manufacturing technology (AMT) to be realized by using masks, including the operation principle of the motor, structure design, technique, driven circuit, and quality examination with Raman spectrum. The μ-micro motor is fabricated by the micro electro-mechanical systems (MEMS) process, the structure design must be considered to fabricate or assembly the parts during machining the motor in the meantime. The research proved that integration of IC (integrated circuit) process and MEMS using masks is effective in obtaining the rapid prototyping manufacturing of the μ-micro motor. With the mature technique to fabricate the motor, there are advantages to produce the motor in short time and with lower cost than before. The motor is a common power source of micro machines in military and civilian applications, for example, applied to micro robot, micro bio medicine, and micro machine. The size of the motor is 190 μm in maximum diameter by 125 μm in height that is bulk machined in array with the number of hundreds of micro motors on a substrate.

关键词： micro motor nontraditional machining advanced manufacturing technology, micro-/nano-tech-nology micro electro-mechanical systems (MEMS) China

Interfacial potential approach for Ag/ZnO (0001) interfaces

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Chinese physics B 2014年第12期23卷 376-381页

作者：宋宏权申江钱萍陈难先 Institute of Applied physics Beijing University of Science and Technology School of physics and mechanical & Electrical engineering Zhoukou Normal University Department of physics Tsinghua University

Systematic approaches are presented to extract the interfacial potentials from the ab initio adhesive energy of the interface system by using the Chen–M ¨obius inversion method. We focus on the interface structure of the metal（111）/Zn O（0001）in this work. The interfacial potentials of Ag–Zn and Ag–O are obtained. These potentials can be used to solve some problems about Ag/Zn O interfacial structure. Three metastable interfacial structures are investigated in order to check these potentials. Using the interfacial potentials we study the procedure of interface fracture in the Ag/Zn O（0001） interface and discuss the change of the energy, stress, and atomic structures in tensile process. The result indicates that the exact misfit dislocation reduces the total energy and softens the fracture process. Meanwhile, the formation and mobility of the vacancy near the interface are observed.

关键词： zinc oxide interfacial potential inversion method misfit dislocation

Influence of the Cd/S Molar Ratio on the Optical and Structural Properties of Nanocrystalline CdS Thin Films

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Journal of Materials Science & Technology 2010年第3期26卷 193-199页

作者： M.Thambidurai N.Murugan N.Muthukumarasamy S.Agilan S.Vasantha R.Balasundaraprabhu3 Department of physics Coimbatore Institute of Technology Department of mechanical engineering Coimbatore Institute of Technology Department of physics PSG College of Technology

Nanocrystalline CdS thin films have been deposited using precursors with different thiourea concentrationonto glass substrates by sol-gel spin coating *** crystalline nature of the films has been observedto be strongly dependent on thiourea concentration and annealing *** CdS films are found tobe nanocrystalline in nature with hexagonal *** grain size is found to be in the range of 7.6 to11.5 nm depending on the thiourea concentration and annealing *** high resolution transmissionelectron microscopy （HRTEM） results of the CdS films prepared using cadmium to thiourea molar ratio of0.3：0.3 indicate the formation of nanocrystalline CdS with grain size of 5 *** transform infrared （FTIR）analysis shows the absorption bands corresponding to Cd and *** optical study carried out to determinethe band gap of the nanostructured CdS thin films shows a strong blue *** band gap energy has beenobserved to lie in the range of 3.97 to 3.62 eV following closely the quantum confinement dependence ofenergy on crystallite *** dependence of band gap of the CdS films on the annealing temperature andthiourea concentration has also been *** photoluminescence （PL） spectra display two main emissionpeaks corresponding to the blue and green emissions of CdS.

关键词： Sol-gel CdS quantum dots High resolution transmission electronmicroscopy (HRTEM)

Phase and particle of Y-doped Ni(OH)_2 prepared from different nickel sources and Na_2CO_3 amount

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Rare Metals 2014年第2期33卷 219-224页

作者： Qing-Sheng Xu Yan-Juan Zhu Liang-Guo Huang Jie Luo Zhong-Ju Zhang Cheng-Cheng Miao Hu Ye School of physics and Optoelectronic engineering Guangdong University of Technology School of mechanical and Electronic engineering Guangdong Institute of Science and Technology

Multiple nano-sized a-Ni（OH）2was synthesized by ultrasonic-assisted precipitation under different conditions. The crystal structure and particle size distribution of the sample were characterized with X-ray diffraction（XRD）, infrared spectroscopy, and laser particle size analyzer（PSA）. The results show that the samples are anisotropic polycrystalline of a and b Ni（OH）2, and the ratio of a and b changes with the difference of nickel source, resulting in the largest ratio of a-Ni（OH）2using nickel nitrate as reactant. Larger amount of Na2CO3is conducive to the formation of a-Ni（OH）2; while the resultant phases are all b with the same conditions but no doping. The results of PSD indicate that the samples are about 100–120 nm in size, and the sample with nickel sulfate as nickel source has the minimum particle size. The three ions of nickel source appear in the absorption peaks in the Fourier transform infrared spectrum showing that the ions change the crystal structure of Ni（OH）2. EDS testing shows that Y and anion distribute in the lattice of aNi（OH）2uniformly.

关键词： Multiphase nano-Ni(OH)2 Y-doping Nickel source

A Numerical Study of Temporal Mixing Layer with Three-Dimensional Mortar Spectral Element Method

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Chinese physics Letters 2011年第6期28卷 187-189页

作者： ZHANG Xu LIU Jin-Hong Jonathan W.N Institute of Fluid physics China Academy of Engineering PhysicsMianyang 621900 mechanical Department University of WyomingLaramieUSA

We investigate a set of well-posed interface conditions of viscous fluxes of Navier–Stokes equations,extend them to three-dimensional Navier–Stokes equations and successfully study a temporally turbulent mixing *** evolution of a large vortex structure and the non-dimensional statistical quantities in the mixing layer are numerically *** span-wise energy spectrum of the mixing layer exhibits wide band features,which means that the simulation generates the desired amount of small *** results show that too many small scales are present due to insufficient dissipation and the amount of large scales is low,indicating too much dissipation for large-scale structures.

关键词： layer mixing dissipation

Mesoscale modeling of microgel mechanics and kinetics through the swelling transition

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Applied Mathematics and Mechanics(English Edition) 2018年第1期39卷 47-62页

作者： S.NIKOLOV A.FERNANDEZ-NIEVES A.ALEXEEV Woodruff School of mechanical engineering Georgia Institute of Technology School of physics Georgia Institute of Technology

The mechanics and swelling kinetics of polymeric microgels are simulated using a mesoscale computational model based on dissipative particle dynamics. Microgels are represented by a random elastic network submerged in an explicit viscous solvent. The model is used to probe the effect of different solvent conditions on the bulk modulus of the microgels. Comparison of the simulation results through the volume phase transition reveals favorable agreement with Flory-Rehner＇s theory for polymeric gels. The model is also used to examine the microgel swelling kinetics, and is found to be in good agreement with Tanaka＇s theory for spherical gels. The simulations show that, during the swelling process, the microgel maintains a nearly homogeneous structure, whereas deswelling is characterized by the formation of chain bundles and network coarsening.

关键词： soft matter dissipative particle dynamics micromechanics hydrogels

Influence of Structural Parameters of Turbocharger Floating Bearing on Its Dynamic Characteristic Coefficients

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Journal of Beijing Institute of Technology 2017年第2期26卷 183-190页

作者： Junsheng Zhao Yuantong Gu Shengxian Yi Xuelong Lu School of mechanical and Power engineering North University of China School of Chemistry Physics and Mechanical EngineeringQueensland University of Technology

The structure parameters in an actual industrial production have a great influence on the coefficient of supercharger floating bearing dynamic characteristics,but there has been little systematic study so *** this paper,the influence of structural parameters of the turbocharger floating bearing on its dynamic characteristic coefficientsis systematically investigated based on the theories of hydrodynamic lubrication and *** influence of clearance ratio on eccentricity and the influence of internal to external radius ratios,and Sommerfeld number were analyzed.A new formula of responding characteristics of the oil film force caused by the displacement or velocity disturbance was deduced near an equilibrium in the steady *** the newly developed formula,the dynamic characteristic was studied for floating *** for change of oil film stiffness and damping was analyzed with the structural parameters of floating bearing such as radius ratios and *** has been found that the clearance ratio increases with eccentricity when the radius ratio is *** eccentricity decreases with the internal to external radius ratio of floating rings when the clearance ratio is *** absolute value of total principal stiffness and total main damping decrease with the clearance ratio and radius ratio of floating rings when the total cross damping is *** results and findings in this paper can contribute to nonlinear dynamics designs of turbocharger rotor-bearing systems.

关键词： turbocharger floating bearing structure parameters dynamic characteristic coefficient

Influence of Change in Inner Layer Thickness of Composite Circular Tube on Second-Harmonic Generation by Primary Circumferential Ultrasonic Guided Wave Propagation

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Chinese physics Letters 2017年第6期34卷 61-65页

作者：李明亮邓明晰高广健陈瀚项延训 Department of physics Logistics Engineering University School of mechanical and Power engineering East China University of Science and Technology

The influence of change in inner layer thickness of a composite circular tube is investigated on second-harmonic generation （SHG） by primary circumferential ultrasonic guided wave （CUGW） propagation. Within a second- order perturbation approximation, the nonlinear effect of primary CUOW propagation is treated as a second-order perturbation to its linear response. It is found that change in inner layer thickness of the composite circular tube will influence the efficiency of SHG by primary CUGW propagation in several aspects. In particular, with change in inner layer thickness, the phase velocity matching condition that is originally satisfied for the primary and double-frequency CUGW mode pair selected may no longer be satisfied. This will remarkably influence the efficiency of SHG by primary CUGW propagation. Theoretical analyses and numerical results show that the effect of SHG by primary CUGW propagation is very sensitive to change in inner layer thickness, and it can be used to accurately monitor a minor change in inner layer thickness of the composite circular tube.

关键词： Harmonic generation