The hot deformation behavior of 7A55 aluminum alloy was investigated at the temperature ranging from 300 ℃ to 450 ℃ and strain rate ranging from 0.01 s-1 to 1 s-1 on a Gleeble-3500 simulator. Processing maps were es...The hot deformation behavior of 7A55 aluminum alloy was investigated at the temperature ranging from 300 ℃ to 450 ℃ and strain rate ranging from 0.01 s-1 to 1 s-1 on a Gleeble-3500 simulator. Processing maps were established in order to apprehend the kinetics of hot deformation and the rate controlling mechanism was interpreted by the kinetic rate analysis obeying power-law relation. The results indicated that one significant domain representing dynamic recrystallization （DRX） existed on the processing maps and lying in 410-450 ＆#176;C and 0.05-1 s-1. The conclusions of kinetic analysis correlated well with those obtained from processing maps. The apparent activation energy values calculated in the dynamic recrystallization （DRX） domain and the stability regions except dynamic recrystallization （DRX） domain were 91.2 kJ/mol and 128.8 kJ/mol, respectively, which suggested that grain boundary self-diffusion and cross-slip were the rate controlling mechanisms.展开更多
Mental imagery generation is essential in the retrieval and storage of knowledge.Previous studies have indicated that the holistic properties of mental imagery generation can be evaluated more easily than the partial ...Mental imagery generation is essential in the retrieval and storage of knowledge.Previous studies have indicated that the holistic properties of mental imagery generation can be evaluated more easily than the partial properties.However,the relationship between partial and holistic mental imagery generations has not been clearly demonstrated.To address this issue,we designed a task to investigate the changes in the spectrum of the electroencephalogram (EEG) during partial or holistic imagery generation.EEG signals were obtained from 18 healthy subjects,and a statistical measure of spectral dynamics between two EEG signals in per frequency band was performed.Additionally,a bicoherence spectrum analysis was used to detect the phase coupling within these two imagery conditions.Our results indicated that EEG of the partial imagery appeared earlier and stronger than that of the holistic imagery in the theta (5–8 Hz) range in a time window around 220 to 300 ms after cue onset,and a slight decrease in the alpha (8–12 Hz) band was observed at around 270 ms.The scalp topography of these changes in the theta and alpha bands distributed overall significantly in the frontal and central-temporal areas.The significant phase coupling within two conditions was remarkable at high frequency.From these results,we infer that there are complex relations between partial and holistic imageries.The generation of partial mental imagery is not a subprocess of holistic imagery,but it is relevant to holistic imagery and requires correct modification from the holistic information.展开更多
基金Project(2012CB619505)supported by the National Basic Research Program of China
文摘The hot deformation behavior of 7A55 aluminum alloy was investigated at the temperature ranging from 300 ℃ to 450 ℃ and strain rate ranging from 0.01 s-1 to 1 s-1 on a Gleeble-3500 simulator. Processing maps were established in order to apprehend the kinetics of hot deformation and the rate controlling mechanism was interpreted by the kinetic rate analysis obeying power-law relation. The results indicated that one significant domain representing dynamic recrystallization （DRX） existed on the processing maps and lying in 410-450 ＆#176;C and 0.05-1 s-1. The conclusions of kinetic analysis correlated well with those obtained from processing maps. The apparent activation energy values calculated in the dynamic recrystallization （DRX） domain and the stability regions except dynamic recrystallization （DRX） domain were 91.2 kJ/mol and 128.8 kJ/mol, respectively, which suggested that grain boundary self-diffusion and cross-slip were the rate controlling mechanisms.
基金Project supported by the National Natural Science Foundation of China (No. 60971096)the National Basic Research Program (973) of China (No. 2006CB504100)
文摘Mental imagery generation is essential in the retrieval and storage of knowledge.Previous studies have indicated that the holistic properties of mental imagery generation can be evaluated more easily than the partial properties.However,the relationship between partial and holistic mental imagery generations has not been clearly demonstrated.To address this issue,we designed a task to investigate the changes in the spectrum of the electroencephalogram (EEG) during partial or holistic imagery generation.EEG signals were obtained from 18 healthy subjects,and a statistical measure of spectral dynamics between two EEG signals in per frequency band was performed.Additionally,a bicoherence spectrum analysis was used to detect the phase coupling within these two imagery conditions.Our results indicated that EEG of the partial imagery appeared earlier and stronger than that of the holistic imagery in the theta (5–8 Hz) range in a time window around 220 to 300 ms after cue onset,and a slight decrease in the alpha (8–12 Hz) band was observed at around 270 ms.The scalp topography of these changes in the theta and alpha bands distributed overall significantly in the frontal and central-temporal areas.The significant phase coupling within two conditions was remarkable at high frequency.From these results,we infer that there are complex relations between partial and holistic imageries.The generation of partial mental imagery is not a subprocess of holistic imagery,but it is relevant to holistic imagery and requires correct modification from the holistic information.
