Conventional advanced high strength steels(AHSS) such as dual-phase,TRIP and martensitic sheet products have undergone extensive development and substantially increased implementation in automobile structures over the...Conventional advanced high strength steels(AHSS) such as dual-phase,TRIP and martensitic sheet products have undergone extensive development and substantially increased implementation in automobile structures over the past few years.Efforts are now underway to extend these improvements and develop steels with even greater strengths and formability.A variety of alloy/process/microstructure/property approaches aimed at next generation AHSS properties are highlighted here.One approach involves the quenching and partitioning process,originally conceived at the Colorado School of Mines,but now being investigated around the global automotive steel development community.Early implementation efforts are underway,and new results demonstrate the capability to obtain ultra-high strength levels with usable ductility.Viewing the field more broadly,it appears that several approaches are converging,and it is likely that additional attention will continue to be placed on expanding the allowable range of austenite stabilizing elements.展开更多
In this work,we analyze and demonstrate a novel photonic-assisted broadband and high-resolution radio frequency(RF) channelization scheme based on dual coherent optical frequency combs(OFCs),regular optical de-muxes,a...In this work,we analyze and demonstrate a novel photonic-assisted broadband and high-resolution radio frequency(RF) channelization scheme based on dual coherent optical frequency combs(OFCs),regular optical de-muxes,and polarization I/Q demodulators in theory and experiment.The use of two coherent combs avoids precise optical alignment,and a numerical filter in digital signal processor(DSP) enables an ideal rectangular frequency response in each channel without any ultra-narrow optical filters.Besides,due to the use of polarization I/Q demodulation,ambiguous frequency estimate in direct detection can be avoided and the amplitude,phase mismatch in traditional I/Q demodulation can be mitigated.In experiment,we use two coherent OFCs with the free spectrum range(FSR) of about 40 GHz to demonstrate the channelization scheme with seven channels,500 MHz channel spacing and frequency coverage from 3.75 GHz to 7.25 GHz.The input RF tones are accurately down-converted to an intermediate frequency(IF) with a maximum frequency error of 110 kHz.Meanwhile,crosstalk and spurious free dynamic range(SFDR) of the scheme are also discussed.展开更多
针对静电驱动微机械谐振传感器接口动态电容的测量,文中介绍了一种读取接口电路,采用了高频方波对振动信号进行调制,模拟开关进行解调。以静电驱动的某真空封装微机械振动双框架陀螺为例,接口电路实验测试得到的波形与设计预期一致,并...针对静电驱动微机械谐振传感器接口动态电容的测量,文中介绍了一种读取接口电路,采用了高频方波对振动信号进行调制,模拟开关进行解调。以静电驱动的某真空封装微机械振动双框架陀螺为例,接口电路实验测试得到的波形与设计预期一致,并利用接口电路和频率扫描方法成功测得微机械振动陀螺驱动模态谐振频率为13.552 k Hz,品质因数为1863。展开更多
文摘Conventional advanced high strength steels(AHSS) such as dual-phase,TRIP and martensitic sheet products have undergone extensive development and substantially increased implementation in automobile structures over the past few years.Efforts are now underway to extend these improvements and develop steels with even greater strengths and formability.A variety of alloy/process/microstructure/property approaches aimed at next generation AHSS properties are highlighted here.One approach involves the quenching and partitioning process,originally conceived at the Colorado School of Mines,but now being investigated around the global automotive steel development community.Early implementation efforts are underway,and new results demonstrate the capability to obtain ultra-high strength levels with usable ductility.Viewing the field more broadly,it appears that several approaches are converging,and it is likely that additional attention will continue to be placed on expanding the allowable range of austenite stabilizing elements.
基金supported in part by the Major State Basic Research Development Program of China ("973" Program) (Grant No. 2012CB315705)National Natural Science Foundation of China (Grant Nos. 61107058, 61120106001)+1 种基金the National High Technology Research and Development Program of China ("863" Program) (Grant No. 2011AA010306)the Fundamental Research Funds for the Central Universities of China
文摘In this work,we analyze and demonstrate a novel photonic-assisted broadband and high-resolution radio frequency(RF) channelization scheme based on dual coherent optical frequency combs(OFCs),regular optical de-muxes,and polarization I/Q demodulators in theory and experiment.The use of two coherent combs avoids precise optical alignment,and a numerical filter in digital signal processor(DSP) enables an ideal rectangular frequency response in each channel without any ultra-narrow optical filters.Besides,due to the use of polarization I/Q demodulation,ambiguous frequency estimate in direct detection can be avoided and the amplitude,phase mismatch in traditional I/Q demodulation can be mitigated.In experiment,we use two coherent OFCs with the free spectrum range(FSR) of about 40 GHz to demonstrate the channelization scheme with seven channels,500 MHz channel spacing and frequency coverage from 3.75 GHz to 7.25 GHz.The input RF tones are accurately down-converted to an intermediate frequency(IF) with a maximum frequency error of 110 kHz.Meanwhile,crosstalk and spurious free dynamic range(SFDR) of the scheme are also discussed.
文摘针对静电驱动微机械谐振传感器接口动态电容的测量,文中介绍了一种读取接口电路,采用了高频方波对振动信号进行调制,模拟开关进行解调。以静电驱动的某真空封装微机械振动双框架陀螺为例,接口电路实验测试得到的波形与设计预期一致,并利用接口电路和频率扫描方法成功测得微机械振动陀螺驱动模态谐振频率为13.552 k Hz,品质因数为1863。
