为给中子导管中子输运与屏蔽计算提供输入参数,建立冷中子源(Cold Neutron Source,CNS)模型,制作正氢与仲氢蒙特卡罗(Monte Carlo N particle transport code,MCNP)截面数据库,计算了慢化室内不同穿透深度的中子注量率变化趋势、冷中子(...为给中子导管中子输运与屏蔽计算提供输入参数,建立冷中子源(Cold Neutron Source,CNS)模型,制作正氢与仲氢蒙特卡罗(Monte Carlo N particle transport code,MCNP)截面数据库,计算了慢化室内不同穿透深度的中子注量率变化趋势、冷中子(Cold Neutron,CN)孔道入口处中子角分布与冷中子增益、中子导管入口处中子角分布与中子注量率空间分布。结果显示,液氢慢化剂使中子束内冷中子有显著的增益,随着中子在CN孔道内的传输中子束的准直性大大提高,为下一步开展中子导管计算提供了重要参考数据。展开更多
针对人体内神经电信号非常微弱、噪声大、环境干扰大等特点,研究与设计了一款应用于神经信号采集的高电源抑制比(PSRR)和共模抑制比(CMRR)的低噪声植入式模拟前端.该模拟前端采用全差分结构来实现模拟前端中的前置放大器、开关电容滤波...针对人体内神经电信号非常微弱、噪声大、环境干扰大等特点,研究与设计了一款应用于神经信号采集的高电源抑制比(PSRR)和共模抑制比(CMRR)的低噪声植入式模拟前端.该模拟前端采用全差分结构来实现模拟前端中的前置放大器、开关电容滤波器及可变增益放大器,使得电路具有较好的电源抑制比和共模抑制比;采用斩波调制技术来抑制电路的低频噪声,并通过带电流数模转换器(DAC)的纹波抑制环路来抑制前置放大器的输出纹波,从而使该模拟前端在具有高PSRR和CMRR的同时能保持低噪声性能.文中采用0.18μm CMOS工艺设计该模拟前端芯片,版图后仿真结果表明,该模拟前端在0.1 Hz^10 k Hz内的等效输入噪声为2.59μV,实现了46.35、52.18、60.02、65.95 d B可调增益,CMRR和PSRR分别可达146及108d B,很好地满足了植入式神经信号采集的要求.展开更多
The rock mass rating(RMR)has been used across the geotechnical industry for half a century.In contrast,the coal mine roof rating(CMRR)was specifically introduced to underground coal mines two decades ago to link geolo...The rock mass rating(RMR)has been used across the geotechnical industry for half a century.In contrast,the coal mine roof rating(CMRR)was specifically introduced to underground coal mines two decades ago to link geological characterization with geotechnical risk mitigation.The premise of CMRR is that strength properties of mine roof rock are influenced by defects typical of coal measures stratigraphy.The CMRR has been used in longwall pillar design,roof support methods,and evaluation of extended cuts,but is rarely evaluated.Here,the RMR and CMRR are applied to a longwall coal mine.Roof rock mass classifications were undertaken at 67 locations across the mine.Both classifications showed marked spatial variability in terms of roof conditions.Normal and reverse faulting occur across the mine,and while no clear relationships exist between rock mass character and faulting,a central graben zone showed heterogeneous rock mass properties,and divergence between CMRR and RMR.Overall,the CMRR data fell within the broad envelope of results reported for extended cuts at Australian and U.S.coal mines.The corollary is that the CMRR is useful,and should not be used in isolation,but rather as a component of a strata control programme.展开更多
A novel high CMRR current output stage (COS) with QFG is presented in this paper. A novel common mode feedback (CMFB) is used to reject the common mode signal in order to achieve high CMRR. The common mode signal is o...A novel high CMRR current output stage (COS) with QFG is presented in this paper. A novel common mode feedback (CMFB) is used to reject the common mode signal in order to achieve high CMRR. The common mode signal is omitted by the technique of adding the main signal and its opposite polarity one. 112 dB of CMRR is obtained in 0.35 μm CMOS technology with ±0.75 v supply voltage and only 182μw power dissipation which shows good improvement compared to the other work in the literature.展开更多
文摘为给中子导管中子输运与屏蔽计算提供输入参数,建立冷中子源(Cold Neutron Source,CNS)模型,制作正氢与仲氢蒙特卡罗(Monte Carlo N particle transport code,MCNP)截面数据库,计算了慢化室内不同穿透深度的中子注量率变化趋势、冷中子(Cold Neutron,CN)孔道入口处中子角分布与冷中子增益、中子导管入口处中子角分布与中子注量率空间分布。结果显示,液氢慢化剂使中子束内冷中子有显著的增益,随着中子在CN孔道内的传输中子束的准直性大大提高,为下一步开展中子导管计算提供了重要参考数据。
文摘针对人体内神经电信号非常微弱、噪声大、环境干扰大等特点,研究与设计了一款应用于神经信号采集的高电源抑制比(PSRR)和共模抑制比(CMRR)的低噪声植入式模拟前端.该模拟前端采用全差分结构来实现模拟前端中的前置放大器、开关电容滤波器及可变增益放大器,使得电路具有较好的电源抑制比和共模抑制比;采用斩波调制技术来抑制电路的低频噪声,并通过带电流数模转换器(DAC)的纹波抑制环路来抑制前置放大器的输出纹波,从而使该模拟前端在具有高PSRR和CMRR的同时能保持低噪声性能.文中采用0.18μm CMOS工艺设计该模拟前端芯片,版图后仿真结果表明,该模拟前端在0.1 Hz^10 k Hz内的等效输入噪声为2.59μV,实现了46.35、52.18、60.02、65.95 d B可调增益,CMRR和PSRR分别可达146及108d B,很好地满足了植入式神经信号采集的要求.
基金Staff at Vale Australia,in particular Lachlan Cunningham and Priscilla Page,are thanked for facilitating underground access to the Carborough Downs Mine.The research was kindly supported by Moultrie Group and Golder Associates.
文摘The rock mass rating(RMR)has been used across the geotechnical industry for half a century.In contrast,the coal mine roof rating(CMRR)was specifically introduced to underground coal mines two decades ago to link geological characterization with geotechnical risk mitigation.The premise of CMRR is that strength properties of mine roof rock are influenced by defects typical of coal measures stratigraphy.The CMRR has been used in longwall pillar design,roof support methods,and evaluation of extended cuts,but is rarely evaluated.Here,the RMR and CMRR are applied to a longwall coal mine.Roof rock mass classifications were undertaken at 67 locations across the mine.Both classifications showed marked spatial variability in terms of roof conditions.Normal and reverse faulting occur across the mine,and while no clear relationships exist between rock mass character and faulting,a central graben zone showed heterogeneous rock mass properties,and divergence between CMRR and RMR.Overall,the CMRR data fell within the broad envelope of results reported for extended cuts at Australian and U.S.coal mines.The corollary is that the CMRR is useful,and should not be used in isolation,but rather as a component of a strata control programme.
文摘A novel high CMRR current output stage (COS) with QFG is presented in this paper. A novel common mode feedback (CMFB) is used to reject the common mode signal in order to achieve high CMRR. The common mode signal is omitted by the technique of adding the main signal and its opposite polarity one. 112 dB of CMRR is obtained in 0.35 μm CMOS technology with ±0.75 v supply voltage and only 182μw power dissipation which shows good improvement compared to the other work in the literature.
