The error sources related to the laser rangefinder,GPS and INS are analyzed in details.Several coordinates systems used in airborne laser scanning are set up,and then the basic formula of system is given.This paper em...The error sources related to the laser rangefinder,GPS and INS are analyzed in details.Several coordinates systems used in airborne laser scanning are set up,and then the basic formula of system is given.This paper emphasizes on discussing the kinematic offset correction between GPS antenna phase center and laser fired point.And kinematic time delay influence on laser footprint position,the ranging errors,positioning errors,attitude errors and integration errors of the system are also explored.Finally,the result shows that the kinematic time delay can be neglected as compared with other error sources.The accuracy of the coordinates is not only influenced by the amplitude of the error,but also controlled by the operation parameters such as flight height,scanning angle amplitude and attitude magnitude of the platform.展开更多
The efficient and safe operation of large fusion devices strongly relies on the plasma configuration inside the vacuum chamber.It is important to construct the proper plasma equilibrium with a desired plasma configura...The efficient and safe operation of large fusion devices strongly relies on the plasma configuration inside the vacuum chamber.It is important to construct the proper plasma equilibrium with a desired plasma configuration.In order to construct the target configuration,a shape constraint module has been developed in the tokamak simulation code（TSC）,which controls the poloidal flux and the magnetic field at several defined control points.It is used to construct the double null,lower single null,and quasi-snowflake configurations for the required target shape and calculate the required PF coils current.The flexibility and practicability of this method have been verified by the simulated results.展开更多
In this paper, a novel timing offset estimation algorithm of low complexity is presented, which needs a few pilots. The results of simulation prove that the system performance with timing offset correction is approxim...In this paper, a novel timing offset estimation algorithm of low complexity is presented, which needs a few pilots. The results of simulation prove that the system performance with timing offset correction is approximate to that over AWGN channel.展开更多
This paper presents an AC coupling ultrasound analog front-end(AFE)architecture with a three-stage DC offset correction(DCOC)circuit.In ultrasound systems,the low noise amplifier(LNA),time gain control(TGC),and low pa...This paper presents an AC coupling ultrasound analog front-end(AFE)architecture with a three-stage DC offset correction(DCOC)circuit.In ultrasound systems,the low noise amplifier(LNA),time gain control(TGC),and low pass filter(LPF)constitute the AFE,which achieves low noise,time-varying gain compensation,and filtering for the received ultrasound signal.The inherent asymmetry in LNA,layout asymmetry and the process variation introduce DC offset and the TGC changes it into low-frequency offset drift.The proposed DCOC circuit for LNA is composed of a transconductance amplifier and an off-chip capacitor,while a fully differential operational amplifier and a pseudo resistor are used for other amplification stages.The AC coupling scheme is also used to reduce the offset and drift.The simulation result shows when the DCOC and the AC coupling are adopted,the offset and drift are almost perfectly suppressed.The proposed AFE has been fabricated by a 28-nm CMOS process,and it achieves an 85 dB gain range with low input-referred noise of 2.43 nV/√Hz at 5 MHz,and it also has a tunable bandwidth of 15/30 MHz and switchable input impedance of 50/100 ohms.展开更多
基金Funded by the National Natural Science Foundation of China(No.40004001)
文摘The error sources related to the laser rangefinder,GPS and INS are analyzed in details.Several coordinates systems used in airborne laser scanning are set up,and then the basic formula of system is given.This paper emphasizes on discussing the kinematic offset correction between GPS antenna phase center and laser fired point.And kinematic time delay influence on laser footprint position,the ranging errors,positioning errors,attitude errors and integration errors of the system are also explored.Finally,the result shows that the kinematic time delay can be neglected as compared with other error sources.The accuracy of the coordinates is not only influenced by the amplitude of the error,but also controlled by the operation parameters such as flight height,scanning angle amplitude and attitude magnitude of the platform.
基金Project supported by the National Magnetic Confinement Fusion Research Program of China(Grant Nos.2014GB103000 and 2014GB110003)the National Natural Science Foundation of China(Grant Nos.11305216,11305209,and 11375191)External Cooperation Program of BIC,Chinese Academy of Sciences(Grant No.GJHZ201303)
文摘The efficient and safe operation of large fusion devices strongly relies on the plasma configuration inside the vacuum chamber.It is important to construct the proper plasma equilibrium with a desired plasma configuration.In order to construct the target configuration,a shape constraint module has been developed in the tokamak simulation code（TSC）,which controls the poloidal flux and the magnetic field at several defined control points.It is used to construct the double null,lower single null,and quasi-snowflake configurations for the required target shape and calculate the required PF coils current.The flexibility and practicability of this method have been verified by the simulated results.
文摘In this paper, a novel timing offset estimation algorithm of low complexity is presented, which needs a few pilots. The results of simulation prove that the system performance with timing offset correction is approximate to that over AWGN channel.
基金supported by the National Key Research and Development Project under Grant 2020YFC0122101.
文摘This paper presents an AC coupling ultrasound analog front-end(AFE)architecture with a three-stage DC offset correction(DCOC)circuit.In ultrasound systems,the low noise amplifier(LNA),time gain control(TGC),and low pass filter(LPF)constitute the AFE,which achieves low noise,time-varying gain compensation,and filtering for the received ultrasound signal.The inherent asymmetry in LNA,layout asymmetry and the process variation introduce DC offset and the TGC changes it into low-frequency offset drift.The proposed DCOC circuit for LNA is composed of a transconductance amplifier and an off-chip capacitor,while a fully differential operational amplifier and a pseudo resistor are used for other amplification stages.The AC coupling scheme is also used to reduce the offset and drift.The simulation result shows when the DCOC and the AC coupling are adopted,the offset and drift are almost perfectly suppressed.The proposed AFE has been fabricated by a 28-nm CMOS process,and it achieves an 85 dB gain range with low input-referred noise of 2.43 nV/√Hz at 5 MHz,and it also has a tunable bandwidth of 15/30 MHz and switchable input impedance of 50/100 ohms.
