Non-standard backward heat conduction problem is ill-posed in the sense that the solution(if it exists) does not depend continuously on the data. In this paper, we propose a regularization strategy-quasi-reversibility...Non-standard backward heat conduction problem is ill-posed in the sense that the solution(if it exists) does not depend continuously on the data. In this paper, we propose a regularization strategy-quasi-reversibility method to analysis the stability of the problem. Meanwhile, we investigate the roles of regularization parameter in this method. Numerical result show that our algorithm is effective and stable.展开更多
Materials data deep-excavation is very important in materials genome exploration.In order to carry out materials data deep-excavation in hot die steels and obtain the relationships among alloying elements,heat treatme...Materials data deep-excavation is very important in materials genome exploration.In order to carry out materials data deep-excavation in hot die steels and obtain the relationships among alloying elements,heat treatment parameters and materials properties,a 11×12×12×4 back-propagation（BP）artificial neural network（ANN）was set up.Alloying element contents,quenching and tempering temperatures were selected as input;hardness,tensile and yield strength were set as output parameters.The ANN shows a high fitting precision.The effects of alloying elements and heat treatment parameters on the properties of hot die steel were studied using this model.The results indicate that high temperature hardness increases with increasing alloying element content of C,Si,Mo,W,Ni,V and Cr to a maximum value and decreases with further increase in alloying element content.The ANN also predicts that the high temperature hardness will decrease with increasing quenching temperature,and possess an optimal value with increasing tempering temperature.This model provides a new tool for novel hot die steel design.展开更多
A non-depletion floating layer silicon-on-insulator （NFL SOI） lateral double-diffused metal–oxide–semiconductor （LDMOS） is proposed and the NFL-assisted modulated field （NFLAMF） principle is investigated in th...A non-depletion floating layer silicon-on-insulator （NFL SOI） lateral double-diffused metal–oxide–semiconductor （LDMOS） is proposed and the NFL-assisted modulated field （NFLAMF） principle is investigated in this paper. Based on this principle, the floating layer can pin the potential for modulating bulk field. In particular, the accumulated high concentration of holes at the bottom of the NFL can efficiently shield the electric field of the SOI layer and enhance the dielectric field in the buried oxide layer （BOX）. At variation of back-gate bias, the shielding charges of NFL can also eliminate back-gate effects. The simulated results indicate that the breakdown voltage （BV） is increased from 315 V to 558 V compared to the conventional reduced surface field （RESURF） SOI （CSOI） LDMOS, yielding a 77% improvement. Furthermore, due to the field shielding effect of the NFL, the device can maintain the same breakdown voltage of 558 V with a thinner BOX to resolve the thermal problem in an SOI device.展开更多
The dynamic thermal process during double-sided asymmetrical TIG backing welding of large thick plates （ 1 000 mm×700 mm×50 mm） is numerically simulated using MSC. MARC. The effect of arc distance on the t...The dynamic thermal process during double-sided asymmetrical TIG backing welding of large thick plates （ 1 000 mm×700 mm×50 mm） is numerically simulated using MSC. MARC. The effect of arc distance on the thermal cycle in weld zone during double-sided asymmetrical T1G backing welding is investigated. The results show that the workpiece experiences double-peak thermal cycle in double-sided asymmetrical TIG backing welding. On the one hand, the fore arc has the pre- heating effect on the rear pass, and the pre-heating temperature depends on the distance between the double arcs, the heat input of fore arc, and the initial temperature of workpiece. On the other hand, the rear arc has the post-heating effect on the fore pass. The mutual effects of two heat sources decrease with the increase of arc distance.展开更多
文摘Non-standard backward heat conduction problem is ill-posed in the sense that the solution(if it exists) does not depend continuously on the data. In this paper, we propose a regularization strategy-quasi-reversibility method to analysis the stability of the problem. Meanwhile, we investigate the roles of regularization parameter in this method. Numerical result show that our algorithm is effective and stable.
文摘Materials data deep-excavation is very important in materials genome exploration.In order to carry out materials data deep-excavation in hot die steels and obtain the relationships among alloying elements,heat treatment parameters and materials properties,a 11×12×12×4 back-propagation（BP）artificial neural network（ANN）was set up.Alloying element contents,quenching and tempering temperatures were selected as input;hardness,tensile and yield strength were set as output parameters.The ANN shows a high fitting precision.The effects of alloying elements and heat treatment parameters on the properties of hot die steel were studied using this model.The results indicate that high temperature hardness increases with increasing alloying element content of C,Si,Mo,W,Ni,V and Cr to a maximum value and decreases with further increase in alloying element content.The ANN also predicts that the high temperature hardness will decrease with increasing quenching temperature,and possess an optimal value with increasing tempering temperature.This model provides a new tool for novel hot die steel design.
文摘A non-depletion floating layer silicon-on-insulator （NFL SOI） lateral double-diffused metal–oxide–semiconductor （LDMOS） is proposed and the NFL-assisted modulated field （NFLAMF） principle is investigated in this paper. Based on this principle, the floating layer can pin the potential for modulating bulk field. In particular, the accumulated high concentration of holes at the bottom of the NFL can efficiently shield the electric field of the SOI layer and enhance the dielectric field in the buried oxide layer （BOX）. At variation of back-gate bias, the shielding charges of NFL can also eliminate back-gate effects. The simulated results indicate that the breakdown voltage （BV） is increased from 315 V to 558 V compared to the conventional reduced surface field （RESURF） SOI （CSOI） LDMOS, yielding a 77% improvement. Furthermore, due to the field shielding effect of the NFL, the device can maintain the same breakdown voltage of 558 V with a thinner BOX to resolve the thermal problem in an SOI device.
文摘The dynamic thermal process during double-sided asymmetrical TIG backing welding of large thick plates （ 1 000 mm×700 mm×50 mm） is numerically simulated using MSC. MARC. The effect of arc distance on the thermal cycle in weld zone during double-sided asymmetrical T1G backing welding is investigated. The results show that the workpiece experiences double-peak thermal cycle in double-sided asymmetrical TIG backing welding. On the one hand, the fore arc has the pre- heating effect on the rear pass, and the pre-heating temperature depends on the distance between the double arcs, the heat input of fore arc, and the initial temperature of workpiece. On the other hand, the rear arc has the post-heating effect on the fore pass. The mutual effects of two heat sources decrease with the increase of arc distance.
