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IEEE/ASME (AIM) International Conference on Advanced Intelligent Mechatronics

作者： Liang Yan Tianyu Wang Zongxia Jiao Chin-Yin Chen I-Ming Chen School of Automation Science and Electrical Engineering Research Institute of Beihang University in Shenzhen Guangdong China Institute of Advanced Manufacturing Technology Ningbo Institute of Material Technology and Engineering Ningbo China School of Mechanical and Aerospace Engineering Nanyang Technological University Singapore

ISBN: (纸本)9781467391085

Conventional linear machine consists of only one stator and one mover. In this paper, a permanent magnet (PM) tubular linear motor with multiple movers is proposed to improve the efficiency of stator field. The outer and inner movers can produce independent motions by interacting with the PM stator. It can be used in large systems requiring multiple driven elements and space saving. The employment of tubular structure helps to reduce the flux leakage and improve the system working efficiency. The design concept and operating principle of the proposed linear machine are introduced. The magnetic field distribution in the machine is formulated by using Laplace's and Poisson's equations of magnetic vector potential. Following that, the modeling of force output for this machine is obtained based on Lorentz law. Numerical computation is also conducted on the flux field. It shows that the derived analytical model fits with the result of finite element analysis (FEA) well.

关键词： Magnetic fields Manganese Force Windings Stators Mathematical model Magnetic flux

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All-dielectric metasurfaces 11

All-dielectric metasurfaces

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11th Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2015

作者： Yang, Yuanmu Moitra, Parikshit Kravchenko, Ivan. I. Briggs, Daryl. P. Valentine, Jason Interdisciplinary Materials Science Program Vanderbilt University NashvilleTN37212 United States Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak RidgeTN37831 United States Department of Mechanical Engineering Vanderbilt University NashvilleTN37212 United States

In this talk, I will discuss our recent efforts to develop purely dielectric metamaterials possessing low absorption loss at optical frequencies. I will discuss implementations ranging from wavefront control to high Q... 详细信息

ISBN: (纸本)9781467371094

关键词： Q factor measurement

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Simulation study of twisted crystal growth in organic thin films

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Physical Review E 2015年第4期92卷 042404-042404页

作者： Alta Fang Mikko Haataja Department of Mechanical and Aerospace Engineering Princeton University Princeton New Jersey 08544 USA. Department of Mechanical and Aerospace Engineering Princeton Institute for the Science and Technology of Materials (PRISM) the Andlinger Center for Energy and the Environment (ACEE) and Program in Applied and Computational Mathematics (PACM) Princeton University Princeton New Jersey 08544 USA.

Many polymer and organic small-molecule thin films crystallize with microstructures that twist or curve in a regular manner as crystal growth proceeds. Here we present a phase-field model that energetically favors twisting of the three-dimensional crystalline orientation about and along particular axes, allowing morphologies such as banded spherulites, curved dendrites, and “s”- or “c”-shaped needle crystals to be simulated. When twisting about the fast-growing crystalline axis is energetically favored and spherulitic growth conditions are imposed, crystallization occurs in the form of banded spherulites composed of radially oriented twisted crystalline fibers. Due to the lack of symmetry, twisting along the normal growth direction leads to heterochiral banded spherulites with opposite twist handedness in each half of the spherulite. When twisting is instead favored about the axis perpendicular to the plane of the substrate and along the normal growth direction under diffusion-limited single-crystalline growth conditions, crystallization occurs in the form of curved dendrites with uniformly rotating branches. We show that the rate at which the branches curve affects not only the morphology but also the overall kinetics of crystallization, as the total crystallized area at a given time is maximized for a finite turning rate.

关键词： Thin films

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Nonlinear Conversion Using Fano-Resonant All-Dielectric Metasurfaces

Nonlinear Conversion Using Fano-Resonant All-Dielectric Meta...

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Nonlinear Optics, NLO 2015

作者： Yang, Yuanmu Boulesbaa, Abdelaziz Kravchenko, Ivan I. Briggs, Dayrl P. Puretzky, Alexander Geohegan, David Valentine, Jason Interdisciplinary Materials Science Program Vanderbilt University NashvilleTN37212 United States Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak RidgeTN37831 United States Department of Mechanical Engineering Vanderbilt University NashvilleTN37212 United States

We present an experimental demonstration of third harmonic generation from Fano-resonant all-dielectric metasurfaces. The metasurfaces have a conversion enhancement factor of 1.5×105 and an absolute conversion ef... 详细信息

ISBN: (纸本)9781557520012

关键词： Fano resonance Localized surface plasmon resonance Mie resonances Nonlinear effects Resonance enhancement Third harmonic generation

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Surface passivation of Fe3O4 nanoparticles with Al2O3 via atomic layer deposition in a rotating fluidized bed reactor

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Journal of Vacuum science & Technology A 2016年第4期34卷

作者： Chen-Long Duan Zhang Deng Kun Cao Hong-Feng Yin Bin Shan Rong Chen State Key Laboratory of Digital Manufacturing Equipment and Technology School of Mechanical Science and Engineering Huazhong University of Science and Technology 1037 Luoyu Road Wuhan Hubei 430074 People's Republic of China Ningbo Institute of Material Technology and Engineering Chinese Academy of Sciences Ningbo Zhejiang 315201 People's Republic of China State Key Laboratory of Material Processing and Die and Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology 1037 Luoyu Road Wuhan Hubei 430074 People's Republic of China State Key Laboratory of Digital Manufacturing Equipment and Technology School of Mechanical Science and Engineering School of Optical and Electronic Information Huazhong University of Science and Technology 1037 Luoyu Road Wuhan Hubei 430074 People's Republic of China

Iron(II,III) oxide (Fe3O4) nanoparticles have shown great promise in many magnetic-related applications such as magnetic resonance imaging, hyperthermia treatment, and targeted drug delivery. Nevertheless, these nanoparticles are vulnerable to oxidation and magnetization loss under ambient conditions, and passivation is usually required for practical applications. In this work, a home-built rotating fluidized bed (RFB) atomic layer deposition (ALD) reactor was employed to form dense and uniform nanoscale Al2O3 passivation layers on Fe3O4 nanoparticles. The RFB reactor facilitated the precursor diffusion in the particle bed and intensified the dynamic dismantling of soft agglomerates, exposing every surface reactive site to precursor gases. With the aid of in situ mass spectroscopy, it was found that a thicker fluidization bed formed by larger amount of particles increased the residence time of precursors. The prolonged residence time allowed more thorough interactions between the particle surfaces and the precursor gas, resulting in an improvement of the precursor utilization from 78% to nearly 100%, even under a high precursor feeding rate. Uniform passivation layers around the magnetic cores were demonstrated by both transmission electron microscopy and the statistical analysis of Al mass concentrations. Individual particles were coated instead of the soft agglomerates, as was validated by the specific surface area analysis and particle size distribution. The results of thermogravimetric analysis suggested that 5 nm-thick ultrathin Al2O3 coatings could effectively protect the Fe3O4 nanoparticles from oxidation. The x-ray diffraction patterns also showed that the magnetic core crystallinity of such passivated nanoparticles could be well preserved under accelerated oxidation conditions. The precise thickness control via ALD maintained the saturation magnetization at 66.7 emu/g with a 5 nm-thick Al2O3 passivation layer. This good preservation of the magnetic properti

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Strongly Nonlinear Discrete Metamaterials: Origin of new Wave Dynamics

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Physics Procedia 2015年 70卷 815-818页

作者： Vitali F. Nesterenko Department of Mechanical and Aerospace Engineering University of California at San Diego La Jolla CA 92093-0411 USA Materials Science and Engineering Program University of California at San Diego La Jolla CA 92093 0418 USA

Discrete metamaterials with strongly nonlinear interactions between elements demonstrate unique behaviour qualitatively different than predicted based on classical linear and weakly nonlinear wave dynamics. The paper provides analysis of theoretical and experimental observations of phenomena related to a new wave dynamics of strongly nonlinear metamaterials.

关键词： strongly nonlinear discrete metamaterials Hertzian chain solitary wave

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Modeling of Magnetic Field and Design Optimization for Permanent-Magnet Spherical Actuator in Three Dimensional Space

Modeling of Magnetic Field and Design Optimization for Perma...

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Conference on Industrial Electronics and Applications

作者： Liang Yan Delong Liu Zongxia Jiao Chin-Yin Chen I-Ming Chen School of Automation Science and Electrical Engineering Beihang University Beijing 100191 China Institute of Advanced Manufacturing Technology Ningbo Institute of Material Technology and Engineering Ningbo China School of Mechanical and Aerospace Engineering Nanyang Technological University 50 Nanyang Avenue Singapore

ISBN: (纸本)9781479984671

Spherical actuator is a device that can achieve multiple degree-of-freedom (DOF) rotary motions in a single joint. This paper proposes a spherical actuator with approximated dihedral cone shaped rotor. To formulate the magnetic field in three dimensional space, Laplace equation is used. By adding the fundamental terms, a more accurate numerical model is set up. It is validated by FEM results in three directions of spherical coordinate. Based on the magnetic field formulation, optimization of spherical actuator is conducted with respect to air gap distance and rotor shape. The optimized parameters can be the foundation of following prototype design.

关键词： spherical actuator magnetic field modeling finite element method design optimization

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Augmented PD Control Method for Permanent Magnet Spherical Actuators with 3D Magnet Array

Augmented PD Control Method for Permanent Magnet Spherical A...

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Conference on Industrial Electronics and Applications

作者： Liang Yan Bo Zhu Zongxia Jiao Chin-Yin Chen I-Ming Chen School of Automation Science and Electrical Engineering Beihang University Beijing 100191 China Institute of Advanced Manufacturing Technology Ningbo Institute of Material Technology and Engineering Ningbo China School of Mechanical and Aerospace Engineering Nanyang Technological University 50 Nanyang Avenue Singapore

ISBN: (纸本)9781479984671

A permanent magnet spherical actuator (PMSA) with 3D magnet array is proposed in this paper. The application of 3D magnet array improves the output torque significantly. However, as PMSA is a nonlinear and multivariable system, it is very complicate to realize accuracy control Therefore, an augmented PD algorithm is proposed in this paper. Compared with the simple PD control method, a feedforward term is added into the proposed algorithm to improve the control performance. Euler angles are applied to describe the orientation of rotor. Lagrange equations are utilized to establish the dynamic model of the actuator. As the center of gravity does not coincide with the center of rotor sphere, gravity torque is taken into consideration to enhance the precision of dynamic model The stability of this algorithm is validated with detailed derivation. Simulation model is formulated in Matlab/Simulink. It proves that the proposed algorithm can make the system track the continuous trajectories in high accuracy.

关键词： permanent magnet spherical actuator 3D magnet array dynamic Model augmented PD control simulation model

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Nature of short, high-amplitude compressive stress pulses in a periodic dissipative laminate

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Physical Review E 2015年第6期92卷 062917-062917页

作者： Pedro Franco Navarro David J. Benson Vitali F. Nesterenko Department of Mechanical and Aerospace Engineering University of California San Diego La Jolla California 92093-0411 USA Department of Structural Engineering University of California San Diego La Jolla California 92093-0085 USA Materials Science and Engineering Program University of California San Diego La Jolla California 92093-0418 USA

We study the evolution of high-amplitude stress pulses in periodic dissipative laminates taking into account the nonlinear constitutive equations of the components and their dissipative behavior. Aluminum-tungsten laminate was selected due to the large difference in acoustic impedances of components, the significant nonlinearity of the aluminum constitutive equation at the investigated range of stresses, and its possible practical applications. Laminates with different cell size, which controls the internal time scale, impacted by plates with different thicknesses that determine the incoming pulse duration, were investigated. It has been observed that the ratio of the duration of the incoming pulse to the internal characteristic time determines the nature of the high-amplitude dissipative propagating waves—a triangular oscillatory shock–like profile, a train of localized pulses, or a single localized pulse. These localized quasistationary waves resemble solitary waves even in the presence of dissipation: The similar pulses emerged from different initial conditions, indicating that they are inherent properties of the corresponding laminates; their characteristic length scale is determined by the scale of mesostructure, nonlinear properties of materials, and the stress amplitude; and a linear relationship exists between their speed and amplitude. They mostly recover their shapes after collision with phase shift. A theoretical description approximating the shape, length scale, and speed of these high-amplitude dissipative pulses was proposed based on the Korteweg–de Vries equation with a dispersive term determined by the mesostructure and a nonlinear term derived using Hugoniot curves of components.

关键词： Aluminum

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Critical Review—Narrow-Band Emission of Nitride Phosphors for Light-Emitting Diodes: Perspectives and Opportunities

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ECS Journal of Solid State science and Technology 2017年第1期7卷

作者： Julius L. Leaño Jr. Mu-Huai Fang Ru-Shi Liu Department of Chemistry National Taiwan University Taipei 106 Taiwan Nanoscience and Technology Program Taiwan International Graduate Program Academia Sinica and National Taiwan University Taipei 106 Taiwan Philippine Textile Research Institute Department of Science and Technology Taguig City 1631 Philippines Department of Mechanical Engineering and Graduate Institute of Manufacturing Technology National Taipei University of Technology Taipei 106 Taiwan E-mail: rsliu@ntu.edu.tw This paper is a Critical Review in Electrochemical and Solid State Science and Technology (CRES3T). This article was reviewed by Anant Setlur (setlur@***) and Jing Wang (ceswj@***).This paper is part of the JSS Focus Issue on Visible and Infrared Phosphor Research and Applications.

Searching for narrow-band red-emitting and thermally stable phosphors is the ultimate strategy toward enhanced performance of phosphor converted light emitting diodes (pc-LED). The red emission is assured by the nitride host because of its relatively more covalent character than oxides and sulfides; however, the narrow emission is attributed to crystallographic, morphological, and electronic considerations. The symmetric coordination site ensures equal ligand effect in all direction fits well with the configuration of Eu2+ f orbitals in the excited state, as observed in cuboid nitrides. Further, thermal stability is ascribed not only to suitable bandgap but more specifically, a relatively distant location of the lowest 5d level from the bottom of the conduction band (CB) that consequently entails high energy to quench excited electrons by exciting them further up to the CB. Modes toward the development of new nitride hosts with potentially narrow-band emission have been identified. A viewpoint on light-emitting diode (LED), backlighting, and laser lighting, which remains the most economically-rewarding phosphors application, is presented. Other exciting frontiers, such as agricultural illumination and persistent luminescence, maximize nitride systems that have other properties other than the stringent narrow-band red emission and excellent thermal stability required for the desired improvement of the mainstream LED application.

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