Preface: Celebrating the 70th Anniversary of School of Mechanical Science and Engineering, Huazhong University of Science and Technology

Abstract

The shifted fractional trapezoidal rule (SFTR) with a special shift is adopted to construct a finite difference scheme for the time-fractional Allen-Cahn (tFAC) equation. Some essential key properties of the weights of SFTR are explored for the first time. Based on these properties, we rigorously demonstrate the discrete energy decay property and maximum-principle preservation for the scheme. Numerical investigations show that the scheme can resolve the intrinsic initial singularity of such nonlinear fractional equations as tFAC equation on uniform meshes without any correction. Comparison with the classic fractional BDF2 and L2-1 σ method further validates the superiority of SFTR in solving the tFAC equation. Experiments concerning both discrete energy decay and discrete maximum-principle also verify the correctness of the theoretical results.

MBD-Based Machining Feature Recognition and Process Route Optimization

“…Berenji et al proposed a decision-making method based on production rules to determine the processing scheme through the selection structure of judgment [22]. Huang established a mathematical model of fuzzy comprehensive evaluation for the decision-making of feature processing schemes and realized the decision-making process by synthesizing the fuzzy relations [23]. Ma et al analyzed the fuzzy mapping relationship between feature attributes and the processing scheme and established a processing scheme decision model based on fuzzy reasoning [24].…”

“…According to µ IT, x j , the fuzzy relationship between the machining accuracy IT and the surface feature machining scheme set X is obtained, which is expressed by the fuzzy matrix R IT×X , as shown below R IT×X = r 1j 1×6 (23) where, r 1j represents the possibility of selecting the machining scheme x j when the machining feature accuracy requirement is IT.…”

Ultra-broadband depolarization based on directly-coupled quantum wire-to-well modulation and their aliasing effect for polarization-insensitive light-emitting diodes

“…In order to achieve this goal, strain modulation based on energy-band engineering is a popularly-used depolarization mechanism and approach to equalize HH and LH contributions in the valence band of the material, as the transverse electric (TE) polarization mode of the device mainly arises from carrier recombination between the conduction band and the HH band, while the transverse magnetic (TM) polarization mode comes from carrier recombination between the conduction band and the LH band. 11,15 For conventional compressive-strained and lattice-matched quantum-confined devices, as the TE optical signal is larger than the TM signal due to the strain and quantum size effects, 16 increasing the TM contribution is necessary to achieve polarization independence. This means that tensile-strained materials must be combined in the active structure to increase carrier recombination between the conduction band and the LH band.…”