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Asymptotic Approximations of Jacobi Functions and Their Zeros with Error Bounds

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Acta Mathematica Sinica,English Series 2006年第3期22卷 729-740页

作者： xiao Feng zhu Xiu Chun LI Department of Basic Science Beijing Institute of Graphic Communication

The study of zeros of orthogonal functions is an important topic. In this paper, by improving the middle variable x（t）, we＇ve got a new form of asymptotic approximation, completed with error bounds, it is constructed for the Jacobi functions φu^（α,β）（t）（α 〉 -1） as μ→∞. Besides, an accurate approximation with error bounds is also constructed correspondingly for the zeros tμ,s of φu^（α,β）（t）（α≥ 0） as μ→∞, uniformly with respect to s = 1, 2,....

关键词： Asymptotic approximation Jacobi function Zero Error bounds

On Complete Hypersurfaces with Constant Mean Curvature and Finite L^p-norm Curvature in R^(n+1)

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Acta Mathematica Sinica,English Series 2005年第3期21卷 631-642页

作者： Yi Bing SHEN xiao Hua zhu Department of Mathematics Zhejiang University Hangzhou 310028 P. R. China School of Mathematical Sciences Peking University Beijing 100871 P. R. China

By using curvature estimates, we prove that a complete non-compact hypersurface M with constant mean curvature and finite L^n-norm curvature in R^1＋1 must be minimal, so that M is a hyperplane if it is strongly stable. This is a generalization of the result on stable complete minimal hypersurfaces of R^n＋1. Moreover, complete strongly stable hypersurfaces with constant mean curvature and finite L^1-norm curvature in R^1＋1 are considered.

关键词： Constant mean curvature Strong stability L^p-norm curvature

THE COMPACTION OF TIME-DEPENDENT VISCOUS GRANULAR MATERIALS CONSIDERING INERTIAL FORCES

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Acta Mechanica Solida Sinica 2011年第6期24卷 495-505页

作者： Yuching Wu Jianzhuang xiao Cimian zhu Department of Building Engineering College of Civil Engineering Tongji University Shanghai 200092 China

In the present paper, compactions of time-dependent viscous granular materials are simulated step by step using the automatic adaptive mesh generation schemes. Inertial forces of the viscous incompressible aggregates axe taken into account. The corresponding conservation equations, the weighted-integral formulations, and penalty finite element model are investigated. The fully discrete finite element equations for the simulation are derived. Polygonal particles of aggregates are simplified as mixed three-node and four-node elements. The automatic adaptive mesh generation schemes include contact detection algorithms, and mesh upgrade schemes. Solu- tions of the numerical simulation axe in good agreement with some results from literatures. With minor modification, the proposed numerical model can be applied in several industries, including the pharmaceutical, ceramic, food, and household product manufacturing.

关键词： granular material automatic adaptive mesh generation finite element method,time-dependent aggregates

A highly efficient and selective probe for F^-detection based on 1H-imidazo[4,5-b]phenazine derivative

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Chinese Chemical Letters 2015年第3期26卷 339-342页

作者： Jin-Yang Hu Rui Liu xiao-Lin zhu xiao Cai Hong-Jun zhu Department of Applied Chemistry College of SciencesNanjing Tech University

A new colorimetric and fluorimetric chemosensor for F detection based on 1H-imidazo[4,5-b]phenazine derivative has been designed and *** shows excellent fluorescent specific selectivity and sensitivity for F^- in DMSO *** addition of F^- to the solution of probe 1,a remarkable color change from yellow to red could be observed easily by the *** detection limit of this probe toward F^- is 6.2× 10 ^-6mol/*** by^1 H NMR proved that the imidazolyl N–H could be hydrogen-bonded with added fluoride anions,and results in the difference of colors.

关键词： naked derivative fluoride colors toward selectivity yellow adding equiv remarkable

Experimental research on the contact force of the bi-directional pig in oil and gas pipeline

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Petroleum Science 2023年第1期20卷 474-481页

作者： xiao-xiao zhu Chun-Ming Fu Yu-Tao Wang Shi-Ming Zhang College of Mechanical and Transportation Engineering China University of Petroleum-BeijingChangpingBeijing102249China

The migration process of the pig in oil and gas pipeline is a complex dynamic *** the pigging operation,the variation of friction force caused by the nonlinear contact between the sealing disc and the pipe wall is the key factor affecting the dynamic characteristics of the pig *** present,the existed pigging models for predicting pigging behavior regard friction as an invariant *** research indicates that the friction force of the pig varies with the contact force and the lubrication ***,the assumption that the friction force is constant cannot reflect the friction dynamic characteristics of the pig during pigging,and will also affect the accuracy of the pigging *** the variation of friction force of pig under different conditions is the basis of establishing the transient dynamic model of a *** a result,in this paper,a method of direct measurement of contact force between the pig and the pipeline is presented,the contact force,the friction force,as well as the friction coefficient of the pig are obtained from the *** results in this paper can help to establish a more accurate dynamic model of pig.

关键词： Pipeline pig Sealing disc Contact force Friction coefficient Experimental rig

Underlying principle of efficient propulsion in flexible plunging foils

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Acta Mechanica Sinica 2014年第6期30卷 839-845页

作者： xiao-Jue zhu Guo-Wei He Xing Zhang LNM Institute of MechanicsChinese Academy of Sciences

Passive flexibility was found to enhance propulsive efficiency in swimming *** this study,we numerically investigate the roles of structural resonance and hydrodynamic wake resonance in optimizing efficiency of a flexible plunging *** results indicates that（1）optimal efficiency is not necessarily achieved when the driving frequency matches the structural eigenfrequency;（2）optimal efficiency always occurs when the driving frequency matches the wake resonant frequency of the time averaged velocity ***,the underlying principle of efficient propulsion in flexible plunging foil is the hydrodynamic wake resonance,rather than the structural *** addition,we also found that whether the efficiency can be optimized at the structural resonant point depends on the strength of the leading edge vortex relative to that of the trailing edge *** result of this work provides new insights into the role of passive flexibility in flapping-based propulsion.

关键词： Flexibility Propulsive efficiency Structural resonance Hydrodynamic wake resonance

Pressure observer based adaptive robust trajectory tracking control of a parallel manipulator driven by pneumatic muscles

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第12期8卷 1928-1937页

作者： zhu xiao-cong TAO Guo-liang CAO Jian The State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

This paper presents a pressure observer based adaptive robust controller (POARC) for posture trajectory tracking of a parallel manipulator driven by three pneumatic muscles without pressure sensors. Due to model errors of the static forces and friction forces of pneumatic muscles, simplified average flow rate characteristics of valves, unknown disturbances of entire system, and unmeasured pressures, there exist rather severe parametric uncertainties, nonlinear uncertainties and dynamic uncertainties in modeling of the parallel manipulator. A nonlinear pressure observer is constructed to estimate unknown pressures on the basis of a single-input-single-output (SISO) decoupling model that is simplified from the actual multiple-input-multiple-output (MIMO) coupling model of the parallel manipulator. Then, an adaptive robust controller integrated with the pressure observer is developed to accomplish high precision posture trajectory tracking of the parallel manipulator. The experimental results indicate that the system with the proposed POARC not only achieves good control accuracy and smooth movement but also maintains robustness to disturbances.

关键词： Pneumatic muscle Parallel manipulator Pressure observer Adaptive robust control Trajectory tracking

Single link tracking scheme based on UWB localization

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Journal of Systems Engineering and Electronics 2009年第6期20卷 1207-1212页

作者： xiao zhu Xiong Hailiang Yu Quan Yi Kechu State Key Lab. of Integrated Service Networks Xidian Univ. Xi'an 710071 P. R. China School of Electronic Science and Engineering National Univ. of Defense Technology Changsha 410073 P. R. China Inst. of China Electronics Equipment System Engineering Corporation Beijing 100039 P. R. China

To investigate the low-complex and high-precise tracking method, a novel single link tracking scheme based on UWB localization is proposed. Two antenna arrays are settled at the fixed station （FS） to receive the UWB signal from mobile terminal （MT）, one FS is enough for the proposed scheme to track the MT. The UWB multipath detection algorithm for time difference of arrival （TDOA） estimation is presented and TDOA is thus adopted to estimate angle of arrival （AOA）, avoiding the synchronization and complicated beamforming for AOA. The impacts of localization errors, concluding multipath and non-line-of-sight （NLOS） errors are simulated for the proposed track scheme. It is demonstrated that the simulation curve can match the real target moving, and the feasibility of the proposed scheme is proved.

关键词： ultra-wide band localization single-link tracking angle of arrival estimation.

High-frequency structure design and RF stability analysis of a 4-vane radio frequency quadrupole with pi-mode stabilizer loops

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Nuclear Science and Techniques 2022年第3期33卷 113-125页

作者： xiao-Wen zhu Claude Marchand Olivier Piquet Michel Desmons IRFU CEAUniversite´Paris-Saclay91191 Gif-sur-YvetteFrance

Compact accelerator-based neutron source facilities are garnering attention and play an important and expanding role in material and engineering sciences,as well as in neutron science education and *** are produced by bombarding a low-energy proton beam onto a beryllium or lithium *** such an acceleratorbased neutron source,a radio frequency quadrupole(RFQ)is usually utilized to accelerate a high-intensity proton beam to a few *** study mainly covers the highfrequency structure design optimizations of a 4-vane RFQ with pi-mode stabilizer loops(PISLs)and its RF stability analysis.A 176 MHz RFQ accelerator is designed to operate at a 10%duty factor and could accelerate an80 mA proton beam from 65 keV to 2.5 MeV within a length of 5.3 *** adoption of PISLs ensures high RF stability,eases the operation of the accelerator,and implies less stringent alignment and machining tolerances.

关键词： Accelerator-based neutron source 4-vane RFQ accelerator Pi-mode stabilizer loops Perturbative analysis Electromagnetic design Multipacting simulation