We report a 1.5-μm InGaAs/GaAs quantum well laser diode grown by molecular beam epitaxy on InGaAs metamorphic buffers. At 150K, for a 1500×10μm^2 ridge waveguide laser, the lazing wavelength is centred at 1.508...We report a 1.5-μm InGaAs/GaAs quantum well laser diode grown by molecular beam epitaxy on InGaAs metamorphic buffers. At 150K, for a 1500×10μm^2 ridge waveguide laser, the lazing wavelength is centred at 1.508 μm and the threshold current density is 667 A/cm^2 under pulsed operation. The pulsed lasers can operate up to 286 K.展开更多
A characteristic CaO-Al2O3-SiO2 based foam ceramic was prepared by melt-foaming with solid wastes as main raw materials.The similarity to sandwich hole wall microstructure of this novel thermal insulating material was...A characteristic CaO-Al2O3-SiO2 based foam ceramic was prepared by melt-foaming with solid wastes as main raw materials.The similarity to sandwich hole wall microstructure of this novel thermal insulating material was presented and the relationships between this unique microstructure and porosity,density,thermal conductivity and strength were discussed.Comparing the measured and theoretical values with that of the traditional foam ceramic,it can be found that,for the matching of fine skeleton with hole wall,this original sandwich structure can reduce thermal conductivity and increase flexural strength effectively.展开更多
Finite element simulations for metal powder compaction of a clutch plate were performed to examine the stresses during compaction,unloading,and ejection.To describe the mechanical behavior of compacted green body,a mo...Finite element simulations for metal powder compaction of a clutch plate were performed to examine the stresses during compaction,unloading,and ejection.To describe the mechanical behavior of compacted green body,a modified densitydependent Drucker-Prager Cap model was utilized to predict the stress and density distribution of the compacted clutch plate during loading and ejection stages.The results indicate that maximum tensile principal stress was a main driving force for the tensile crack initiation during ejection stage,and shear stress may be another driving force in both compaction and ejection stages for shear crack initiation.There were peak value of the stresses during ejection stage,and the stresses are in compressive state only during compaction stage.Therefore,the tensile crack initiation is not possible during compaction except shear crack.Hoop stress in the clutch plate is of less contribution to the crack initiation during compaction,unloading and ejection.Study of criteria of the crack initiation and fracture is necessary in order to obtain uniform density and crackfree components in the manufacturing of metal powder compaction.展开更多
基金Supported partly by the National Natural Science Foundation of China under Grand Nos 60607016 and 60625405, the National Basic Research Programme of China and the National High Technology Research and Development Programme of China.
文摘We report a 1.5-μm InGaAs/GaAs quantum well laser diode grown by molecular beam epitaxy on InGaAs metamorphic buffers. At 150K, for a 1500×10μm^2 ridge waveguide laser, the lazing wavelength is centred at 1.508 μm and the threshold current density is 667 A/cm^2 under pulsed operation. The pulsed lasers can operate up to 286 K.
基金financial support of the project from the National Natural Science Foundation of China(51172016)。
文摘A characteristic CaO-Al2O3-SiO2 based foam ceramic was prepared by melt-foaming with solid wastes as main raw materials.The similarity to sandwich hole wall microstructure of this novel thermal insulating material was presented and the relationships between this unique microstructure and porosity,density,thermal conductivity and strength were discussed.Comparing the measured and theoretical values with that of the traditional foam ceramic,it can be found that,for the matching of fine skeleton with hole wall,this original sandwich structure can reduce thermal conductivity and increase flexural strength effectively.
基金The authors gratefully acknowledge the financial supports of State Key Lab of Advanced Welding and Joining,Harbin Institute of Technology(Nos.AWJ-19Z05).
文摘Finite element simulations for metal powder compaction of a clutch plate were performed to examine the stresses during compaction,unloading,and ejection.To describe the mechanical behavior of compacted green body,a modified densitydependent Drucker-Prager Cap model was utilized to predict the stress and density distribution of the compacted clutch plate during loading and ejection stages.The results indicate that maximum tensile principal stress was a main driving force for the tensile crack initiation during ejection stage,and shear stress may be another driving force in both compaction and ejection stages for shear crack initiation.There were peak value of the stresses during ejection stage,and the stresses are in compressive state only during compaction stage.Therefore,the tensile crack initiation is not possible during compaction except shear crack.Hoop stress in the clutch plate is of less contribution to the crack initiation during compaction,unloading and ejection.Study of criteria of the crack initiation and fracture is necessary in order to obtain uniform density and crackfree components in the manufacturing of metal powder compaction.
