An InP optical 90°hybrid based on a×4 MMI coupler with a deep ridged waveguide is designed and fabricated.The working principle of the 90°hybrid is systematically introduced.Three-dimensional beam ropag...An InP optical 90°hybrid based on a×4 MMI coupler with a deep ridged waveguide is designed and fabricated.The working principle of the 90°hybrid is systematically introduced.Three-dimensional beam ropagation method(3D BPM)is used to optimize the structure parameters of the 90°hybrid.The designed compact structure is demonatrated to have a low excess loss less than-0.15 dB,a high common mode rejection ratio better than 40 dB,and a low relative phase deviation less than±2.5°.The designed hybrid is manufactured on a sandwitched structure deposited on an InP substrate.The measured results show that the common mode rejection ratios are larger than 20 dB in a range from 1520 nm to 1580 nm.The phase deviations are less than±5°in a range from 1545 nm to 1560 nm and less than±7°across the C band.The designed 90°optical hybrid is suitable well for realizing miniaturization,high-properties,and high bandwidth of coherent receiver.展开更多
A control method of active front steering(AFS)based on active disturbance rejection technique was proposed for solving the model nonlinearity and parameter decoupling control in the traditional control methods.The AFS...A control method of active front steering(AFS)based on active disturbance rejection technique was proposed for solving the model nonlinearity and parameter decoupling control in the traditional control methods.The AFS controller consists of the proportional and derivative(PD)feed-forward controller and the active disturbance rejection feedback controller.To improve the steering response characteristics of a vehicle,a PD controller is designed to realize variable steering gear ratio,and to enhance the safety of vehicle when steering.An active disturbance rejection controller(ADRC)is designed to follow the expected yaw rate of the vehicle.According to the input and output of system,extended state observer(ESO)of ADRC can dynamically estimate internal and external disturbance of the system,thus easily realizing the model nonlinear and parameter decoupling control.The AFS controller is simulated and validated in Matlab and CarSim.The simulating results of double lane change(DLC)test and pylon course slalom(PCS)test show that the ADRC can well control the vehicle model to complete the road simulation test of DLC and PCS with small path tracking error.The simulating results of angle step test of steering wheel show that the vehicle under the control of ADRC demonstrates good lateral response characteristic.The controller regulates a wide range of parameters.The model has less precision requirements with good robustness.展开更多
在现有产品基础上加以改进,设计一种高精度低噪声低压差线性稳压器电路。设计采用折叠式共源共栅结构放大器来降低噪声,提高增益;使用PMOS管代替过热保护电路中的电阻,降低功耗,同时采用栅极驱动结构以及电流控制方式实现开关管导通与...在现有产品基础上加以改进,设计一种高精度低噪声低压差线性稳压器电路。设计采用折叠式共源共栅结构放大器来降低噪声,提高增益;使用PMOS管代替过热保护电路中的电阻,降低功耗,同时采用栅极驱动结构以及电流控制方式实现开关管导通与关断。基于TSMC 0.35μm B iCMOS工艺结合Cadence软件进行设计、版图绘制和前、后仿真,在后仿真中得出相关参数值。对各参数做出详细分析,并对不同频率下的电源电压抑制比进行了对比。实验结果表明本设计达到了高精度低功耗的设计目标。展开更多
The influence of external low frequency (0-100 Hz) vibration on the tip-sample interaction in SPM is the main concern of this paper. A concept, vibration rejection ratio (VRR) proposed by Thompson et al, was investiga...The influence of external low frequency (0-100 Hz) vibration on the tip-sample interaction in SPM is the main concern of this paper. A concept, vibration rejection ratio (VRR) proposed by Thompson et al, was investigated theoretically and experimentally. A concise theoretical background was introduced, a vibration stimulating and measuring system for SPM was built up, and an experimental research of the influence on SPM VRR was carried out with different SPM probes, samples, tip pre-loads and open/close loops of tip-sample interaction. It was proved both in theory and experiment that SPM VRR had correlations with the spring constant, the air damping constant, the effective mass of the cantilever, the contact spring constant and the contact damping constant between tip and sample. SPM's vibration rejecting ability can be improved by longer cantilever probe, softer sample surface, greater tip pre-load, and close-loop control for tip-sample interaction. More attention should be paid to a proper combination of the above parameters.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFB0402404)the Beijing Natural Science Foundation,China(Grant No.4194093)the National Natural Science Foundation of China(Grant Nos.61635010,61674136,and 61435002).
文摘An InP optical 90°hybrid based on a×4 MMI coupler with a deep ridged waveguide is designed and fabricated.The working principle of the 90°hybrid is systematically introduced.Three-dimensional beam ropagation method(3D BPM)is used to optimize the structure parameters of the 90°hybrid.The designed compact structure is demonatrated to have a low excess loss less than-0.15 dB,a high common mode rejection ratio better than 40 dB,and a low relative phase deviation less than±2.5°.The designed hybrid is manufactured on a sandwitched structure deposited on an InP substrate.The measured results show that the common mode rejection ratios are larger than 20 dB in a range from 1520 nm to 1580 nm.The phase deviations are less than±5°in a range from 1545 nm to 1560 nm and less than±7°across the C band.The designed 90°optical hybrid is suitable well for realizing miniaturization,high-properties,and high bandwidth of coherent receiver.
基金supported by the National Natural Science Foundation of China(No.51205191)
文摘A control method of active front steering(AFS)based on active disturbance rejection technique was proposed for solving the model nonlinearity and parameter decoupling control in the traditional control methods.The AFS controller consists of the proportional and derivative(PD)feed-forward controller and the active disturbance rejection feedback controller.To improve the steering response characteristics of a vehicle,a PD controller is designed to realize variable steering gear ratio,and to enhance the safety of vehicle when steering.An active disturbance rejection controller(ADRC)is designed to follow the expected yaw rate of the vehicle.According to the input and output of system,extended state observer(ESO)of ADRC can dynamically estimate internal and external disturbance of the system,thus easily realizing the model nonlinear and parameter decoupling control.The AFS controller is simulated and validated in Matlab and CarSim.The simulating results of double lane change(DLC)test and pylon course slalom(PCS)test show that the ADRC can well control the vehicle model to complete the road simulation test of DLC and PCS with small path tracking error.The simulating results of angle step test of steering wheel show that the vehicle under the control of ADRC demonstrates good lateral response characteristic.The controller regulates a wide range of parameters.The model has less precision requirements with good robustness.
文摘在现有产品基础上加以改进,设计一种高精度低噪声低压差线性稳压器电路。设计采用折叠式共源共栅结构放大器来降低噪声,提高增益;使用PMOS管代替过热保护电路中的电阻,降低功耗,同时采用栅极驱动结构以及电流控制方式实现开关管导通与关断。基于TSMC 0.35μm B iCMOS工艺结合Cadence软件进行设计、版图绘制和前、后仿真,在后仿真中得出相关参数值。对各参数做出详细分析,并对不同频率下的电源电压抑制比进行了对比。实验结果表明本设计达到了高精度低功耗的设计目标。
基金Supported by National Natural Science Foundation of China (No.60372006 and No.50305025)
文摘The influence of external low frequency (0-100 Hz) vibration on the tip-sample interaction in SPM is the main concern of this paper. A concept, vibration rejection ratio (VRR) proposed by Thompson et al, was investigated theoretically and experimentally. A concise theoretical background was introduced, a vibration stimulating and measuring system for SPM was built up, and an experimental research of the influence on SPM VRR was carried out with different SPM probes, samples, tip pre-loads and open/close loops of tip-sample interaction. It was proved both in theory and experiment that SPM VRR had correlations with the spring constant, the air damping constant, the effective mass of the cantilever, the contact spring constant and the contact damping constant between tip and sample. SPM's vibration rejecting ability can be improved by longer cantilever probe, softer sample surface, greater tip pre-load, and close-loop control for tip-sample interaction. More attention should be paid to a proper combination of the above parameters.
