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Enhanced phase-coding method for three-dimensional shape measurement with half-period codeword

APPLIED OPTICS 2019年第27期58卷 7359-7366页

作者： Wang, Yuwei Liu, Lu Wu, Jun Chen, Xiangcheng Wang, Yajun Anhui Agr Univ Coll Engn Hefei 230036 Anhui Peoples R China Wuhan Univ Technol Sch Automat Wuhan 430070 Hubei Peoples R China Wuhan Univ State Key Lab Informat Engn Surveying Mapping & R Wuhan 430079 Hubei Peoples R China

The phase-coding method has been widely used for 3D shape measurement, which uses sinusoidal phase-shifting patterns to recover the wrapped phase and the stair phase-coding patterns to determine the fringe order. However, due to random noises and image blurring, the fringe order is always misaligned with the wrapped phase, which will lead to fringe order errors. This paper presents an enhanced phase-coding method to address this misalignment problem by using half-period codewords, in which each codeword is aligned to the half-period of the sinusoidal patterns. Then, two complementary fringe orders with half-period dislocation can be calculated, which can effectively eliminate the fringe order errors. To extend the coding range of stair phase, this paper further develops a computational scheme based on the geometric constraint method. Simulations and experiments have been carried out, and their results confirm that the enhanced method can reliably recover the 3D shape of the measured objects. (C) 2019 Optical Society of America

关键词： 3D shape measurement image blur interference pattern phase coding codeword random noise Half Life fringe order computational scheme shape measurement

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Symplectic Accelerated Optimization on SO(3) with Lie Group Variational Integrators

Symplectic Accelerated Optimization on SO(3) with Lie Group ...

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American Control Conference

作者： Harsh Sharma Taeyoung Lee Mayuresh Patil Craig Woolsey Department of Aerospace and Ocean Engineering Virginia Polytechnic Institute and State University Blacksburg VA Mechanical and Aerospace Engineering The George Washington University Washington DC

ISBN: (数字)9781538682661

ISBN: (纸本)9781538682678

This paper presents computational schemes for optimizing a real-valued function defined on the special orthogonal group. Gradient-based optimization algorithms on a Lie group are interpreted as a continuous-time dynamic system on the group, which is discretized by a Lie group variational integrator that concurrently preserves the symplecticity and the group structure of Hamiltonian systems. It is shown that the proposed approach yields symplectic, accelerated optimization schemes on the special orthogonal group, analogous to classical momentum method. The efficacy of the proposed method is illustrated by numerical examples with an application to spherical shape matching.

关键词： Lie group Group Structure integrators Optimization algorithms computational scheme Orthogonal

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Experimental and Theoretical Justification of Designing a Cable Line Exposed to Cryogenic Cracking

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SOIL MECHANICS AND FOUNDATION ENGINEERING 2018年第4期55卷 284-290页

作者： Zheleznyak, I. I. Ivin, I. A. Russian Acad Sci RAN Inst Nat Resources Ecol & Cryol Siberian Branch Chita Russia

The natural conditions of the South of Transbaikal cryolithic zone are considered, which determine the specifics of thermomechanical processes in seasonally frozen dispersive soils. A justification is provided for calculation of underground cable exposed to cryogenic soil cracking based on thermoelastic model of soil deformation. The calculation scheme of the model is provided along with the limit-state based formulas for calculating the effect of cryogenic cracking on underground cable. The effective devices and methods are described for ensuring protection of the underground linear constructions from damage caused by cryogenic cracks.

关键词： cable NATURAL CONDITIONS computational scheme Underground cables underground Transbaikalia dispersive soils

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Some New High-Order computational Methods for Polar Decomposition of Complex Matrices

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IRANIAN JOURNAL OF SCIENCE AND TECHNOLOGY TRANSACTION A-SCIENCE 2018年第A4期42卷 2293-2299页

作者： Kiyoumarsi, Farshad Islamic Azad Univ Shahrekord Branch Fac Basic Sci Shahrekord Iran

This paper aims at providing some new iterative methods for finding polar decomposition. It is discussed that how we could construct such methods with global convergence. Error analyses for the methods are given to theoretically show their convergence rates. Eventually, computational aspects on many ill-conditioned matrices are brought forward to reveal the applicability of the proposed numerical schemes.

关键词： Polar decomposition Polar factor computational scheme Convergence analysis

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An Analytic Solution Study for a 7-DOF Redundant Robot Manipulator 8

An Analytic Solution Study for a 7-DOF Redundant Robot Manip...

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8th IEEE Annual International Conference on Cyber Technology in Automation, Control, and Intelligent Systems (IEEE-CYBER)

作者： Yang, Lei Zhang, George Shenzhen Acad Robot Shenzhen Shenzhen Peoples R China

ISBN: (纸本)9781538670576

Solving redundant robot kinematics inverse is difficult and critical for redundant robot kinematics. There is no unified solution formula for the general inverse solution of redundant robot structures. In this paper we present the kinematic quantities and computational schemes that are relevant in the kinematic description of a typical redundant manipulator named SIR700 with 7 DOE (degree of freedom) developed by Shenzhen Academy of Robotics. SIR700 has a character in geometric that Joint 3 and Joint 5 are not on the same plane, while Joint 2, Joint 4 and Joint 6 can form a triangle. An extra constraint is introduced based on that theta(4) is solved in the solution of geometric first, then el, theta(1), theta(2), theta(3) and eg, theta(5), theta(6), theta(7) arc solved in the solution of algebraic form.

关键词： manipulator kinematics redundant manipulators Robot kinematics Redundant manipulators Redundant robot Solutions kinematics Joints Joints Solution computational scheme

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Chemical model for positively charged dust particles

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PHYSICS OF PLASMAS 2018年第12期25卷 120701-120701页

作者： Davletov, A. E. Kurbanov, F. Mukhametkarimov, Ye. S. Al Farabi Kazakh Natl Univ Dept Phys & Technol 71 Al Farabi Av Alma Ata 050040 Kazakhstan

A chemical model of electron-dust plasmas consisting of electrons and dust particles is systematically developed. An insight is exploited that a single dust particle forms a potential well for electrons, whose depth is determined by the work function of the dust material. The whole electron fluid, initially concentrated inside the dust particles, is somehow reallocated between the bulk of the dust matter and the ambient space available, which is then interpreted as thermionic emission. An expression is employed for the Helmholtz free energy of the system, which includes the ideal and excess parts to thoroughly deal with interactions between the dusty plasma constituents. Numerical calculations of dust particle charge are performed in quite a broad domain of plasma parameters, and a straightforward comparison is made with the orbital motion limited (OML) approximation to demonstrate that the proposed calculation scheme predicts higher positive charge values of dust grains. It is also proved that the OML approximation exactly corresponds to the ideal-gas model when interactions between plasma particles are entirely neglected. Published by AIP Publishing.

关键词： Work function Quantum confinement Dust particles Chemical Models Cations DIRT Helmholtz free energy POSITIVELY-CHARGED computational scheme orbital motion

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HYDRA-IBRAE/LM/V1 Thermohydraulic Code Verification Based on BN-600 Experiments

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ATOMIC ENERGY 2017年第5期122卷 311-318页

作者： Klimonov, I. A. Usov, E. V. Dugarov, G. A. Butov, A. A. Kudashov, I. G. Ivanov, E. N. Mosunova, N. A. Strizhov, V. F. Anfimov, A. M. Gorbunov, V. S. Kuznetsov, D. V. Osipov, S. L. Bel'tyukov, A. I. Russian Acad Sci IBRAE RAN Inst Problems Safe Dev Nucl Energy Novosibirsk Branch Novosibirsk Russia Russian Acad Sci IBRAE RAN Inst Problems Safe Dev Nucl Energy Moscow Russia Afrikantov Expt Design Bur Mech Engn OKBM Afrikan Nizhnii Novgorod Russia Beloyarskaya Nucl Power Plant Beloyarskaya Nucl Power Plant Zarechnyi Russia

The results of thermohydraulic code HYDRA-IBRAE/LM/V1 verification on experimental data obtained using the BN-600 reactor in different years are described. The particulars of the computational scheme of the reactor using HYDRA-IBRAE/LM/V1 for modeling the BN-600 operating regime are presented. In preparing the scheme, special attention was devoted to accurate modeling of the reactor cool-down regimes on natural circulation as being most important from the safety validation standpoint. The computational results obtained with the uncertainty of the initial data taken into account are presented for such a cool-down regime.

关键词： RAW DATA Reactors BELOYARSK-3 REACTOR Experimental data Codes computational scheme Natural convection thermohydraulics Verification

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Control-oriented modeling of colloid transport by solute gradients in dead-end channels

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ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING 2017年第2期12卷 247-258页

作者： Chen, Tehuan Xu, Chao Ningbo Univ Fac Mech Engn & Mech Ningbo 315211 Zhejiang Peoples R China Zhejiang Univ State Key Lab Ind Control Technol Hangzhou 310027 Zhejiang Peoples R China

When colloids are placed in the nonuniform solute concentration, they transfer toward or away from the higher solute concentration side. This phenomenon is called diffusiophoresis, which is widely founded in many solute-particle interaction processes. In this paper, we consider the colloid transport by solute gradients in dead-end channels with a boundary solute concentration being manipulated, which is a step-like concentration input. We model this process by a coupled solute-particle system, which involves the solute diffusion model and the colloid transport model, and establish a control-oriented model, which is important for controller strategy synthesis in practice. We use the method of separation of variables to obtain the analytical solution of the solute diffusion model and proposed an effective computational scheme for solving the colloid transport model. Thus, we give the simulation results of colloid transfer by considering different boundary solute concentration inputs and show the effectiveness and feasibility for more flexible external control. Finally, because the control-oriented modeling is a switching system governed by partial differential equations essentially, we reformulate the colloid transfer control problem and discuss this problem in detailed from the viewpoint of the computational optimal control. Copyright (c) 2017 Curtin University of Technology and John Wiley & Sons, Ltd.

关键词： diffusiophoresis solute-particle system boundary solute concentration control control-oriented model computational scheme switching control problem computational optimal control

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Aeroelastic Semiphysical Simulation and Wind-Tunnel Testing Validation of a Fin-Actuator System

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JOURNAL OF AIRCRAFT 2017年第1期54卷 235-245页

作者： Wu, Zhigang Zhang, Renjia Ma, Chengji Yang, Chao Beihang Univ Sch Aeronaut Sci & Engn Beijing 100191 Peoples R China China Acad Launch Vehicle Technol Beijing Inst Astronaut Syst Engn Beijing 100076 Peoples R China

An all-moving fin-actuator model was designed to explore the principles and methods of aeroelastic semiphysical simulations. Both mathematical analyses and wind-tunnel tests were conducted to support and verify the simulation. The dynamic characteristics of the actuator were introduced into the flutter calculations, which were also compared to a conventional flutter algorithm. Shakers were used to generate aerodynamic forces in the simulation. A nonlinear variable-structure controller was developed to solve the force coupling problems between shakers. The real-time aerodynamic calculation scheme and the locations of sensors were specifically designed for the test model used in this study. Good agreements were achieved for the flutter boundaries using these approaches. The semiphysical simulation was thus shown to be an economical and practical method for solving aeroelastic problems. This work enriches the literature on aeroelastic simulation methodologies.

关键词： actuators TUNNEL TEST wind tunnel tests simulating flutter practical methods experimental model computational scheme Oscillators controller structure Aeroelastics mathematical analysis

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Dynamics of threading dislocations in porous heteroepitaxial GaN films

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PHYSICS OF THE SOLID STATE 2017年第12期59卷 2394-2400页

作者： Gutkin, M. Yu. Rzhavtsev, E. A. Russian Acad Sci Inst Problems Mech Engn St Petersburg 199178 Russia Peter Great St Petersburg State Polytech Univ St Petersburg 195251 Russia ITMO Univ St Petersburg 197101 Russia

Behavior of threading dislocations in porous heteroepitaxial gallium nitride (GaN) films has been studied using computer simulation by the two-dimensional discrete dislocation dynamics approach. A computational scheme, where pores are modeled as cross sections of cylindrical cavities, elastically interacting with unidirectional parallel edge dislocations, which imitate threading dislocations, is used. Time dependences of coordinates and velocities of each dislocation from dislocation ensembles under investigation are obtained. Visualization of current structure of dislocation ensemble is performed in the form of a location map of dislocations at any time. It has been shown that the density of appearing dislocation structures significantly depends on the ratio of area of a pore cross section to area of the simulation region. In particular, increasing the portion of pores surface on the layer surface up to 2% should lead to about a 1.5-times decrease of the final density of threading dislocations, and increase of this portion up to 15% should lead to approximately a 4.5-times decrease of it.

关键词： Threading dislocations computational scheme final density Porous location map dynamics TIME DEPENDENCE gallium nitrate Cross section

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