为优化地铁暗挖车站支护参数,提供设计依据,明确锚杆在不同预应力下支护效果的差异,采用FLAC3D建立隧道数值模型,通过锚固剂和link参数分段赋值处理实现锚杆托盘段、自由段、锚固段模拟,并赋予预应力,以某地铁6号线暗挖车站为分析对象,...为优化地铁暗挖车站支护参数,提供设计依据,明确锚杆在不同预应力下支护效果的差异,采用FLAC3D建立隧道数值模型,通过锚固剂和link参数分段赋值处理实现锚杆托盘段、自由段、锚固段模拟,并赋予预应力,以某地铁6号线暗挖车站为分析对象,与常规非预应力锚杆进行对比,结合现场应用与现场监测进行结果反馈。数值计算结果显示:1)锚杆预应力使围岩拉应力区显著减小或消失,塑性区减小;2)改善围岩应力状态的主动支护作用明显;3)当预应力达到40 k N以上时,拱顶塑性区消失,边墙最大拉应力为36.3 k Pa;4)当预应力为80 k N时效果显著,拱顶无塑性区,边墙最大拉应力减小到13.9 k Pa;5)现场监测数据显示,格栅钢架最大压应力为34 MPa,混凝土最大压应变为249με,拱顶最大沉降为2.3 mm,在预应力锚杆支护下隧道安全稳定。展开更多
由于光电导天线的太赫兹(Terahertz THz)辐射效率较低,根据光电导天线设计原理设计了一种新的光电导天线结构,该结构在蝶形光电导天线电极间隙处增添了金纳米棒阵列,阵列按正三角形排列,通过时域有限差分法(Finite Difference Time Doma...由于光电导天线的太赫兹(Terahertz THz)辐射效率较低,根据光电导天线设计原理设计了一种新的光电导天线结构,该结构在蝶形光电导天线电极间隙处增添了金纳米棒阵列,阵列按正三角形排列,通过时域有限差分法(Finite Difference Time Domain, FDTD)对所提结构和蝶形光电导天线结构进行仿真模拟。模拟结果表明此结构与蝶形光电导天线相比,光吸收率提高了269%,电场强度提高了985%,光电流提高了两倍。研究结果为实现太赫兹光电导天线的高功率转换效率提供了一种有前景的方法。展开更多
The original online version of this article （Journal of Electronics （China）, Vol. 28, No.3, May 2011, pp.389-395; DOI： 10.1007/s11767-011-0549-1） unfortunately contains a mistake on the author affiliation of Page...The original online version of this article （Journal of Electronics （China）, Vol. 28, No.3, May 2011, pp.389-395; DOI： 10.1007/s11767-011-0549-1） unfortunately contains a mistake on the author affiliation of Page 389. The correct form is given below：展开更多
Short gate-length High Electron Mobility Transistors (HEMTs) have been observed to exhibit kinks in their drain current-voltage (I-V) characteristics. To model this nonlinear effect, we present an effective approach t...Short gate-length High Electron Mobility Transistors (HEMTs) have been observed to exhibit kinks in their drain current-voltage (I-V) characteristics. To model this nonlinear effect, we present an effective approach that is easily incorporated into most existing empirical HEMT I-V models. This has been done by modifying the channel length modulation parameter to account for the kink effect. Moreover, the definitions of the left parameters in the original model will not be influenced, and the improved HEMT I-V model enhances its bias range of operation for which accuracy is maintained. The proposed modeling method is validated through DC/ Pulsed I-V as well as large-signal power measurements.展开更多
文摘为优化地铁暗挖车站支护参数,提供设计依据,明确锚杆在不同预应力下支护效果的差异,采用FLAC3D建立隧道数值模型,通过锚固剂和link参数分段赋值处理实现锚杆托盘段、自由段、锚固段模拟,并赋予预应力,以某地铁6号线暗挖车站为分析对象,与常规非预应力锚杆进行对比,结合现场应用与现场监测进行结果反馈。数值计算结果显示:1)锚杆预应力使围岩拉应力区显著减小或消失,塑性区减小;2)改善围岩应力状态的主动支护作用明显;3)当预应力达到40 k N以上时,拱顶塑性区消失,边墙最大拉应力为36.3 k Pa;4)当预应力为80 k N时效果显著,拱顶无塑性区,边墙最大拉应力减小到13.9 k Pa;5)现场监测数据显示,格栅钢架最大压应力为34 MPa,混凝土最大压应变为249με,拱顶最大沉降为2.3 mm,在预应力锚杆支护下隧道安全稳定。
文摘The original online version of this article （Journal of Electronics （China）, Vol. 28, No.3, May 2011, pp.389-395; DOI： 10.1007/s11767-011-0549-1） unfortunately contains a mistake on the author affiliation of Page 389. The correct form is given below：
文摘Short gate-length High Electron Mobility Transistors (HEMTs) have been observed to exhibit kinks in their drain current-voltage (I-V) characteristics. To model this nonlinear effect, we present an effective approach that is easily incorporated into most existing empirical HEMT I-V models. This has been done by modifying the channel length modulation parameter to account for the kink effect. Moreover, the definitions of the left parameters in the original model will not be influenced, and the improved HEMT I-V model enhances its bias range of operation for which accuracy is maintained. The proposed modeling method is validated through DC/ Pulsed I-V as well as large-signal power measurements.
