An aligned mixture probabilistic principal component analysis for fault detection of multimode chemical processes

A novel approach named aligned mixture probabilistic principal component analysis(AMPPCA) is proposed in this study for fault detection of multimode chemical processes. In order to exploit within-mode correlations,the AMPPCA algorithm first estimates a statistical description for each operating mode by applying mixture probabilistic principal component analysis(MPPCA). As a comparison, the combined MPPCA is employed where monitoring results are softly integrated according to posterior probabilities of the test sample in each local model. For exploiting the cross-mode correlations, which may be useful but are inadvertently neglected due to separately held monitoring approaches, a global monitoring model is constructed by aligning all local models together. In this way, both within-mode and cross-mode correlations are preserved in this integrated space. Finally, the utility and feasibility of AMPPCA are demonstrated through a non-isothermal continuous stirred tank reactor and the TE benchmark process.

Tailoring the Texture and Mechanical Properties of Textured-AZ31 Mg Alloy Sheets by Twinning and Recrystallization

In this study,a method of corrugated width limit alignment processes(CWLA)was applied to pre-twin in hot-rolled Mg alloy sheets.The microstructure evolution and mechanical properties of the CWLA sheets were studied.The results demonstrated that the grain orientation was transformed from strong basal texture to RD-rotated texture after CWLA treatment and up to 22.2%of{10-12}tensile twin boundaries were produced in the microstructure.The 60±5°<10-10>twin variant pairs were dominant in the twinned microstructure.Two kinds of dynamic recrystallization(DRX)mechanism,i.e.,continuous DRX(CDRX)at low-temperature CWLA and the discontinuous DRX(DDRX)at high-temperature condition were observed.After post-annealing,the twin-induced static recrystallization(SRX)and abnormal grain growth were observed in the CWLA samples,and most twin boundaries were retained.After CAWL for 60 min at 300℃ and post annealing,an improvement on plasticity and strength were achieved with 55%increment for uniform elongation(UE)and 10%increment for ultimate tensile strength(UTS).