Donghua University

About: Donghua University is a education organization based out in Shanghai, China. It is known for research contribution in the topics: Fiber & Nanofiber. The organization has 21155 authors who have published 21841 publications receiving 393091 citations. The organization is also known as: Dōnghuá Dàxué & China Textile University.

Limit cycle and bifurcation of nonlinear problems

Abstract: In this paper a simple but effective iteration method is proposed to search for limit cycles or bifurcation curves of nonlinear equations. Some examples are given to illustrate its convenience and effectiveness.

Three‐dimensional velocity field of present‐day crustal motion of the Tibetan Plateau derived from GPS measurements

Abstract: [1] Using the measurements of 750 GPS stations around the Tibetan Plateau for over 10 years since 1999, we derived a high-resolution 3-D velocity field for the present-day crustal movement of the plateau. The horizontal velocity field relative to stable Eurasia displays in details the crustal movement and tectonic deformation features of the India-Eurasia continental collision zone with thrust compression, lateral extrusion, and clockwise rotation. The vertical velocity field reveals that the Tibetan Plateau is continuing to rise as a whole relative to its stable north neighbor. However, in some subregions, uplift is insignificant or even negative. The main features of the vertical crustal deformation of the plateau are the following: (a) The Himalayan range is still rising at a rate of ~2 mm/yr. The uplift rate is ~6 mm/yr with respect to the south foot of the Himalayan range. (b) The middle eastern plateau has a typical uplift rate between 1 and 2 mm/yr, and some high mountain ranges in this area, like the Longmen Shan and Gongga Shan, have surprising uplift rates as large as 2–3mm/yr. (c) In the middle southern plateau, there is a basin and endorheic subregion with a series of NS striking normal faults, showing obvious sinking with the rates between 0 and -3 mm/yr. (d) The present-day rising and sinking subregions generally correspond well to the Cenozoic orogenic belts and basins, respectively. (e) At the southeastern corner of the plateau. There is an apparent trend that the uplift rate is gradually decreasing from between 0.8 and 2.3 mm/yr in the inner plateau to between -0.5 and -1.6 mm/yr outside the plateau, with the decrease of terrain height.

The variational iteration method which should be followed

Abstract: This paper proposes three standard variational iteration algorithms for solving differential equations, integro-differential equations, fractional differential equations, fractal differential equations, differential-difference equations and fractional/fractal differential-difference equations. The physical interpretations of the fractional calculus and the fractal derivative are given and an application to discrete lattice equations is discussed. The paper then examines the acceleration of some iteration formulae with particular emphasis being placed on the exponential Pade approximant that is suggested for solitary solutions and the sinusoidal Pade approximant that is usually used for periodic and compacton solutions. The paper points out that there may not be any physical meaning to the exact solutions of many nonlinear equations and stresses the importance of searching for approximate solutions that satisfy both the equations and the appropriate initial/boundary conditions. The variational iteration method is particularly suitable for solving this kind of problems. Approximate initial/boundary conditions and point boundary initial/conditions are also discussed, with the variational iteration method being capable of recovering the correct initial/boundary conditions and finding the solutions simultaneously.

Microwave Absorption Enhancement of Porous Carbon Fibers Compared with Carbon Nanofibers

Abstract: Porous carbon fibers (pores of: 0.1–3 μm in diameter) and carbon nanofibers (∼100 nm in diameter) were prepared from polyacrylonitrile/polymethyl methacrylate (PAN/PMMA) blend fibers with 70/30 and...

Experimental study on relationship between jet instability and formation of beaded fibers during electrospinning

Abstract: Ultrafine fibers produced by electrospinning often exhibit bead-on-string structures, which have generally been considered to be undesirable “by-products” or defects. Theoretical analysis in the literature predicted three types of instabilities for an electrically driven jet: the axisymmetric Rayleigh instability, the electric field-induced axisymmetric, and whipping instability. The process of bead formation revealed that the formation of a beaded structure resulted from axisymmetric deformation and flow of the jet. Applied voltage, solution surface tension, and conductivity (or jet charge density carried by the moving jet) were theoretically demonstrated to be important for jet axisymmetric instabilities. Experimental results revealed that these parameters influenced the formation of beaded fibers in the same manner as they did for the axisymmetric instabilities. As a result, the axisymmetric instabilities were considered to be the most likely mechanism of beaded fibers formation during electrospinning. POLYM. ENG. SCI., 45:704–709, 2005. © 2005 Society of Plastics Engineers