Most operating radar systems don′t have sufficient frequency bandwidth to produce high range resolution(HRR) profile of a target. But we can use stepped frequency waveform in a narrow band coherent radar to obtai...Most operating radar systems don′t have sufficient frequency bandwidth to produce high range resolution(HRR) profile of a target. But we can use stepped frequency waveform in a narrow band coherent radar to obtain the HRR profile of a target. For moving targets which are of great importance in practical radar usage, autofocusing,i.e. phase correction, is a necessary and critical step of the synthetic HRR processing. The purpose of autofocusing is to remove the radial motion effect of the target from radar echoes, and only reserve the stepped frequency effect which is the basis of synthetic HRR capability. We investigate two autofocusing approaches for synthetic HRR radars using stepped frequency waveform in this paper. The first is motion fitting method. This method depends on a certain parametric model, and is computationally expensive. Then we propose the iterative dominant scatterer method. It is robust, non parametric and simple in computation in comparison with the motion fitting method. Experimental results based on data acquired by using a metallised scale model B 52 in a microwave anechoic chamber reveal the validity and effectiveness of the method.展开更多
Aim To study the influence of radar-target relative speed on frequency MMW high-resolution ore-dimension distance profile and the compensation for it. Methods Based on the distance travelled by the electromagnetic wa...Aim To study the influence of radar-target relative speed on frequency MMW high-resolution ore-dimension distance profile and the compensation for it. Methods Based on the distance travelled by the electromagnetic wave, analyses were made for the compensation algorithm and the expression of the inverse FFT base distance was given.The relative importance of different compensation terms was studied in great detail. The concept of searching compensation was put forward. Results and Condclusion Dcm-△Dvimis the be distance of inverse FFT transformation, the effect caused by the distance △Dim on one-dimension profile is negligible, and the effect caused by the distance Dvim should not be neglected and must be compensated.展开更多
Mechanical micro-vibration of a target may induce phase modulations on the radar echo,and the vibration can be detected to identify micro-motion target. In this paper,a new method to detect a micro-motion target and o...Mechanical micro-vibration of a target may induce phase modulations on the radar echo,and the vibration can be detected to identify micro-motion target. In this paper,a new method to detect a micro-motion target and obtain its range and micro-motion frequency is proposed in which multiple periods stepped-frequency continuous-wave signal and Moving Target Indication (MTI) filter are adopted. The simulation results illustrate the validity of this method and present the detection of the target range and the vibration frequency. The experiment gives promising results.展开更多
OBJECTIVE:To investigate the relationship of electro-parameters and the electroacupuncture sensation(EAS),which is thought to be an important factor for optimal treatment.METHODS:The frequency steps and compositions o...OBJECTIVE:To investigate the relationship of electro-parameters and the electroacupuncture sensation(EAS),which is thought to be an important factor for optimal treatment.METHODS:The frequency steps and compositions of three frequently used electrical stimulations were set when the switch of the electroacupuncture apparatus was turned to the second or third grade of the dense-disperse frequency wave(DD2and DD3,respectively) or the second grade of the continuous wave(C2).Three groups of patients according to the three electroacupuncture stimulations were divided again into three sub-groups according to the stimulated acupoints:the face acupoint Quanliao(SI 18),the upper-limb acupoint Quchi(LI 11) and the back acupoint Dachangshu(BL25).The EAS values were measured every 5 min during 30 min electroacupuncture treatments using a visual analogue scale.RESULTS:The frequency compositions of the three electroacupuncture stimulations were 3.3 and 33 Hz,12.5 and 66.7 Hz,and 3.3 and 3.3 Hz;each frequency step was 30,54 and 0 Hz,respectively.In each sub-group of the C2 group,the EAS values from 10 to 30 min were significantly weaker than at 0 min.The sensation fluctuations in the DD2 and DD3 groups were different during the 30 min.CONCLUSION:The greater the frequency step of the electroacupuncture stimulation,the longer the needling sensation lasted.The electroacupuncture stimulations of the DD3 group were unsuitable for the facial acupoint because of its painful and uncomfortable EAS,but more suitable for the back acupoint.展开更多
文摘Most operating radar systems don′t have sufficient frequency bandwidth to produce high range resolution(HRR) profile of a target. But we can use stepped frequency waveform in a narrow band coherent radar to obtain the HRR profile of a target. For moving targets which are of great importance in practical radar usage, autofocusing,i.e. phase correction, is a necessary and critical step of the synthetic HRR processing. The purpose of autofocusing is to remove the radial motion effect of the target from radar echoes, and only reserve the stepped frequency effect which is the basis of synthetic HRR capability. We investigate two autofocusing approaches for synthetic HRR radars using stepped frequency waveform in this paper. The first is motion fitting method. This method depends on a certain parametric model, and is computationally expensive. Then we propose the iterative dominant scatterer method. It is robust, non parametric and simple in computation in comparison with the motion fitting method. Experimental results based on data acquired by using a metallised scale model B 52 in a microwave anechoic chamber reveal the validity and effectiveness of the method.
文摘Aim To study the influence of radar-target relative speed on frequency MMW high-resolution ore-dimension distance profile and the compensation for it. Methods Based on the distance travelled by the electromagnetic wave, analyses were made for the compensation algorithm and the expression of the inverse FFT base distance was given.The relative importance of different compensation terms was studied in great detail. The concept of searching compensation was put forward. Results and Condclusion Dcm-△Dvimis the be distance of inverse FFT transformation, the effect caused by the distance △Dim on one-dimension profile is negligible, and the effect caused by the distance Dvim should not be neglected and must be compensated.
文摘Mechanical micro-vibration of a target may induce phase modulations on the radar echo,and the vibration can be detected to identify micro-motion target. In this paper,a new method to detect a micro-motion target and obtain its range and micro-motion frequency is proposed in which multiple periods stepped-frequency continuous-wave signal and Moving Target Indication (MTI) filter are adopted. The simulation results illustrate the validity of this method and present the detection of the target range and the vibration frequency. The experiment gives promising results.
基金Supported by National Natural Science Fund of China(Research on the Muscle Cell IGF1/PI3K/AKT Pathway Mechanism of Electroacupuncture Treatment for Muscular Atrophy of TCM Flaccidity(No.81373733)Autonomous Momentous Project of the Fujian Institute of Traditional Chinese Medicine(No.2012fjzyyk-1)
文摘OBJECTIVE:To investigate the relationship of electro-parameters and the electroacupuncture sensation(EAS),which is thought to be an important factor for optimal treatment.METHODS:The frequency steps and compositions of three frequently used electrical stimulations were set when the switch of the electroacupuncture apparatus was turned to the second or third grade of the dense-disperse frequency wave(DD2and DD3,respectively) or the second grade of the continuous wave(C2).Three groups of patients according to the three electroacupuncture stimulations were divided again into three sub-groups according to the stimulated acupoints:the face acupoint Quanliao(SI 18),the upper-limb acupoint Quchi(LI 11) and the back acupoint Dachangshu(BL25).The EAS values were measured every 5 min during 30 min electroacupuncture treatments using a visual analogue scale.RESULTS:The frequency compositions of the three electroacupuncture stimulations were 3.3 and 33 Hz,12.5 and 66.7 Hz,and 3.3 and 3.3 Hz;each frequency step was 30,54 and 0 Hz,respectively.In each sub-group of the C2 group,the EAS values from 10 to 30 min were significantly weaker than at 0 min.The sensation fluctuations in the DD2 and DD3 groups were different during the 30 min.CONCLUSION:The greater the frequency step of the electroacupuncture stimulation,the longer the needling sensation lasted.The electroacupuncture stimulations of the DD3 group were unsuitable for the facial acupoint because of its painful and uncomfortable EAS,but more suitable for the back acupoint.
