BACKGROUND： According to observable behaviors, sleep and wakefulness are two fundamentally different behavioral states. Although electroencephalogram （EEG） is traditionally used to define sleep stage, it is difficu...BACKGROUND： According to observable behaviors, sleep and wakefulness are two fundamentally different behavioral states. Although electroencephalogram （EEG） is traditionally used to define sleep stage, it is difficult to detect or to quantify microarousals or disruptions during sleep. In addition initial sleep cannot be defined. It is thought that the wake-sleep transition cannot be defined by EEG patterns. OBJECTIVE： To observe the behavioral response magnitude during wake-sleep transition by EEG monitoring and to define the wake-sleep transition. DESIGN, TIME AND SETTING： A behavioral and neural network study was performed at the Key Lab of Human Being Development and Mental Health of Central China Normal University, and Lab of Brain and Cognitive Science of South Central University for Nationalities, China in July 2007. PARTICIPANTS： A total of 30 healthy volunteers, of equal gender and aged （19.7 ± 1.1 ） years, were recruited from the Central China Normal University, China for this study. None of the subjects had undergone EEG recording prior to this study or received any medication for sleep disturbances. METHODS： A novel adaptive approach was applied to detect wake-sleep transition, which avoided stimulus-induced waking. To test the difference between wake state and wake-sleep transition, the amount of self-information and mutual-information were effective parameters to analyze wake-sleep transition. MAIN OUTCOME MEASURES： The following parameters were measured： morphological changes in reaction time-magnitude, as well as correlation between phase changes and sleep, and wake and wake-sleep transition. RESULTS： There were three typical phases in morphological changes of reaction time-magnitude. With regard to the behavioral definition and criterion for sleep, the phase morphological characteristics displayed good correlation with behavioral states, such as sleep, wakefulness, and sleep onset. Entropy as an indicator of brain cognitive processes was introduced to test for differences between the wakefulness and sleep onset phase. Results indicated a cognitive declined transitional period different between sleep and wake. After staggered cognitive changes during the wake-sleep transition, the brain underwent marked alterations and transitioned into sleep quickly with no bi-directional EEG changes. CONCLUSION： Wake-sleep transition exists as an independent stage.展开更多
Presently developed two-phase turbulence models under-predict the gas turbulent fluctuation, because their turbulence modification models cannot fully reflect the effect of particles. In this paper, a two-time-scale d...Presently developed two-phase turbulence models under-predict the gas turbulent fluctuation, because their turbulence modification models cannot fully reflect the effect of particles. In this paper, a two-time-scale dis- sipation model of turbulence modification, developed for the two-phase velocity correlation and for the dissipation rate of gas turbulent kinetic energy, is proposed and used to simulate sudden-expansion and swirling gas-particle flows. The proposed two-time scale model gives better results than the single-time scale model. Besides, a gas tur- bulence augmentation model accounting for the finite-size particle wake effect in the gas Reynolds stress equation is proposed. The proposed turbulence modification models are used to simulate two-phase pipe flows. It can prop- erly predict both turbulence reduction and turbulence enhancement for a certain size of particles observed in ex- periments.展开更多
Multi-Threshold CMOS(MTCMOS) is an effective technique for controlling leakage power with low delay overhead.However the large magnitude of ground bouncing noise induced by the sleep to active mode transition may caus...Multi-Threshold CMOS(MTCMOS) is an effective technique for controlling leakage power with low delay overhead.However the large magnitude of ground bouncing noise induced by the sleep to active mode transition may cause signal integrity problem in MTCMOS circuits.We propose a methodology for reducing ground bouncing noise under the wake-up delay constraint.An improved two-stage parallel power gating structure that can suppress the ground bouncing noise through turn on sets of sleep transistors consecutively is proposed.The size of each sleep transistor is optimized by a novel sizing algorithm based on a simple discharging model.Simulation results show that the proposed techniques achieve at least 23% improvement in the product of the peak amplitude of ground bouncing noise and the wake-up time when compared with other existing techniques.展开更多
文摘BACKGROUND： According to observable behaviors, sleep and wakefulness are two fundamentally different behavioral states. Although electroencephalogram （EEG） is traditionally used to define sleep stage, it is difficult to detect or to quantify microarousals or disruptions during sleep. In addition initial sleep cannot be defined. It is thought that the wake-sleep transition cannot be defined by EEG patterns. OBJECTIVE： To observe the behavioral response magnitude during wake-sleep transition by EEG monitoring and to define the wake-sleep transition. DESIGN, TIME AND SETTING： A behavioral and neural network study was performed at the Key Lab of Human Being Development and Mental Health of Central China Normal University, and Lab of Brain and Cognitive Science of South Central University for Nationalities, China in July 2007. PARTICIPANTS： A total of 30 healthy volunteers, of equal gender and aged （19.7 ± 1.1 ） years, were recruited from the Central China Normal University, China for this study. None of the subjects had undergone EEG recording prior to this study or received any medication for sleep disturbances. METHODS： A novel adaptive approach was applied to detect wake-sleep transition, which avoided stimulus-induced waking. To test the difference between wake state and wake-sleep transition, the amount of self-information and mutual-information were effective parameters to analyze wake-sleep transition. MAIN OUTCOME MEASURES： The following parameters were measured： morphological changes in reaction time-magnitude, as well as correlation between phase changes and sleep, and wake and wake-sleep transition. RESULTS： There were three typical phases in morphological changes of reaction time-magnitude. With regard to the behavioral definition and criterion for sleep, the phase morphological characteristics displayed good correlation with behavioral states, such as sleep, wakefulness, and sleep onset. Entropy as an indicator of brain cognitive processes was introduced to test for differences between the wakefulness and sleep onset phase. Results indicated a cognitive declined transitional period different between sleep and wake. After staggered cognitive changes during the wake-sleep transition, the brain underwent marked alterations and transitioned into sleep quickly with no bi-directional EEG changes. CONCLUSION： Wake-sleep transition exists as an independent stage.
基金State Key Development Program for Basic Research of China (No.2006CB200305), the National Natural Sci-ence Foundation of China (No.50376004), and Ph.D. Program Foundation of Ministry of Education of China (No.20030007028).
文摘Presently developed two-phase turbulence models under-predict the gas turbulent fluctuation, because their turbulence modification models cannot fully reflect the effect of particles. In this paper, a two-time-scale dis- sipation model of turbulence modification, developed for the two-phase velocity correlation and for the dissipation rate of gas turbulent kinetic energy, is proposed and used to simulate sudden-expansion and swirling gas-particle flows. The proposed two-time scale model gives better results than the single-time scale model. Besides, a gas tur- bulence augmentation model accounting for the finite-size particle wake effect in the gas Reynolds stress equation is proposed. The proposed turbulence modification models are used to simulate two-phase pipe flows. It can prop- erly predict both turbulence reduction and turbulence enhancement for a certain size of particles observed in ex- periments.
基金Supported by the National Natural Science Foundation of China (No. 6087001)
文摘Multi-Threshold CMOS(MTCMOS) is an effective technique for controlling leakage power with low delay overhead.However the large magnitude of ground bouncing noise induced by the sleep to active mode transition may cause signal integrity problem in MTCMOS circuits.We propose a methodology for reducing ground bouncing noise under the wake-up delay constraint.An improved two-stage parallel power gating structure that can suppress the ground bouncing noise through turn on sets of sleep transistors consecutively is proposed.The size of each sleep transistor is optimized by a novel sizing algorithm based on a simple discharging model.Simulation results show that the proposed techniques achieve at least 23% improvement in the product of the peak amplitude of ground bouncing noise and the wake-up time when compared with other existing techniques.
