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Yu D.,Tianjin University | Chen G.,Tianjin University | Yu W.,Nuclear Power Institute of China | Li D.,Guangdong University of Petrochemical Technology | Chen X.,Tianjin University
International Journal of Plasticity | Year: 2012

Experimental results of monotonic uniaxial tensile tests at different strain rates and the reversed strain cycling test showed the characteristics of rate-dependence and cyclic hardening of Z2CND18.12N austenitic stainless steel at room temperature, respectively. Based on the Ohno-Wang kinematic hardening rule, a visco-plastic constitutive model incorporated with isotropic hardening was developed to describe the uniaxial ratcheting behavior of Z2CND18.12N steel under various stress-controlled loading conditions. Predicted results of the developed model agreed better with experimental results when the ratcheting strain level became higher, but the developed model overestimated the ratcheting deformation in other cases. A modified model was proposed to improve the prediction accuracy. In the modified model, the parameter mi of the Ohno-Wang kinematic hardening rule was developed to evolve with the accumulated plastic strain. Simulation results of the modified model proved much better agreement with experiments. © 2011 Elsevier Ltd. All rights reserved.

Hu S.,South China Normal University | Hu S.,Guangdong University of Petrochemical Technology | Ma X.,South China Normal University | Lu D.,South China Normal University | And 2 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

The existence and stability of defect solitons in parity-time (PT) symmetric optical lattices with nonlocal nonlinearity are reported. It is found that nonlocality can expand the stability region of defect solitons. For positive or zero defects, fundamental and dipole solitons can exist stably in the semi-infinite gap and the first gap, respectively. For negative defects, fundamental solitons can be stable in both the semi-infinite gap and the first gap, whereas dipole solitons are unstable in the first gap. There exist a maximum degree of nonlocal nonlinearity, above which the fundamental solitons in the semi-infinite gap and the dipole solitons in the first gap do not exist for negative defects. The influence of the imaginary part of the PT-symmetric potentials on soliton stability is given. When the modulation depth of the PT-symmetric lattices is small, defect solitons can be stable for positive and zero defects, even if the PT-symmetric potential is above the phase transition point. © 2012 American Physical Society.

Xin Y.,Nanjing University of Science and Technology | He Y.,Guangdong University of Petrochemical Technology | Chen Y.,Nanjing University of Science and Technology | Li J.,Nanjing University of Science and Technology
Optics Letters | Year: 2010

The correlation between intensity fluctuations of light scattered from a quasi-homogeneous random media was analytically derived. We showed the correlation depends on spatial Fourier transforms of both the intensity and degree of spatial correlation of scattering potentials of the media, while the normalized correlation equals the squared modulus of the degree of spatial coherence of the scattered fields. © 2010 Optical Society of America.

Wang F.,Guangdong University of Petrochemical Technology
Advances in Science and Technology of Water Resources | Year: 2014

In order to investigate the fractal features of meandering rivers, the divider dimension was used as a parameter to describe the internal structure of river patterns. It is proven that the divider dimension is equal to the Housdorff dimension. The divider dimensions of the lower Jingjiang River and its three local sections in six historical periods from 1496 to 2013 were computed, quantitatively characterizing the evolution laws of the river patterns. The results show that, compared with the sinuosity coefficient, the divider dimensions can better characterize the river pattern and its evolution laws.

Hu S.,Guangdong University of Petrochemical Technology | Hu W.,South China Normal University
Journal of Physics B: Atomic, Molecular and Optical Physics | Year: 2012

Optical solitons in the parity-time (PT)-symmetric Bessel complex potential are studied, including the linear case, and self-focusing and self-defocusing nonlinear cases. For the linear case, the PT-symmetric breaking points, eigenvalues and the eigenfunction for different modulated depths of the PT-symmetric Bessel complex potential are obtained numerically. The PT-symmetric breaking points increase linearly with increasing the real part of the modulated depths of the PT potential. Below the PT-symmetric breaking points, the eigenfunctions of linear modes are symmetrical; however, the symmetries of the eigenfunction break above the PT-symmetric breaking points. For nonlinear cases, the existence and stability of fundamental and multipole solitons are studied in self-focusing and self-defocusing media. The eigenvalue for the linear case is equal to the critical propagation constant b c of the existing soliton. Fundamental solitons are stable in the whole region and multipole solitons are stable with the propagation constants being close to b c both for self-focusing and self-defocusing nonlinearities. The range of solitons stability decreases with an increase of the number of the intensity peaks of the solitons. © 2012 IOP Publishing Ltd.

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