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Scale effect removal and range migration correction for hypersonic target coherent detection
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作者 WU Shang SUN Zhi +4 位作者 JIANG Xingtao ZHANG Haonan DENG Jiangyun LI Xiaolong CUI Guolong 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2024年第1期14-23,共10页
The detection of hypersonic targets usually confronts range migration(RM)issue before coherent integration(CI).The traditional methods aiming at correcting RM to obtain CI mainly considers the narrow-band radar condit... The detection of hypersonic targets usually confronts range migration(RM)issue before coherent integration(CI).The traditional methods aiming at correcting RM to obtain CI mainly considers the narrow-band radar condition.However,with the increasing requirement of far-range detection,the time bandwidth product,which is corresponding to radar’s mean power,should be promoted in actual application.Thus,the echo signal generates the scale effect(SE)at large time bandwidth product situation,influencing the intra and inter pulse integration performance.To eliminate SE and correct RM,this paper proposes an effective algorithm,i.e.,scaled location rotation transform(ScLRT).The ScLRT can remove SE to obtain the matching pulse compression(PC)as well as correct RM to complete CI via the location rotation transform,being implemented by seeking the actual rotation angle.Compared to the traditional coherent detection algorithms,Sc LRT can address the SE problem to achieve better detection/estimation capabilities.At last,this paper gives several simulations to assess the viability of ScLRT. 展开更多
关键词 hypersonic target detection coherent integration(CI) scale effect(SE)removal range migration(RM)correction scaled location rotation transform(ScLRT)
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Research on Open-circuit Fault Tolerant Control of Six-phase Permanent Magnet Synchronous Machine Based on Fifth Harmonic Current Injection 被引量:3
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作者 Zhifeng Zhang Yue Wu +1 位作者 Hequn Su Quanzeng Sun 《CES Transactions on Electrical Machines and Systems》 CSCD 2022年第3期306-314,共9页
This paper proposes a novel control approach for fault-tolerant control of dual three-phase permanent magnet synchronous motor(PMSM) under one-phase open-circuit fault.A modified six-phase static coordinate transforma... This paper proposes a novel control approach for fault-tolerant control of dual three-phase permanent magnet synchronous motor(PMSM) under one-phase open-circuit fault.A modified six-phase static coordinate transformation matrix and an extended rotating coordinate transformation matrix are investigated considering the influence of the fifth harmonic space on fault-tolerant control. These mathematical models are further analyzed in the fundamental space and the fifth harmonic space after the fault and to eliminate the coupling between the d-q axis voltage equation in the fundamental wave space and the d-q axis voltage equation in the fifth harmonic space, a secondary rotation coordinate transformation matrix is proposed. To achieve the purpose of reducing torque ripple, the fault-tolerant control method proposed in this paper not only takes the minimum copper loss as the constraint condition, but also injects the fifth harmonic current. The experimental result of current and torque is used to verify the accuracy of fault-tolerant control. 展开更多
关键词 Extended rotating coordinate transformation matrix Fault-tolerant control Fifth harmonic current injection Modified six-phase static coordinate transformation matrix Dual three-phase permanent magnet synchronous motor Torque ripple
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Atmospheric Excitation of Time Variable Length-of-Day on Seasonal Scales 被引量:4
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作者 Li-Hua Ma Yan-Ben Han 《Chinese Journal of Astronomy and Astrophysics》 CSCD 2006年第1期120-124,共5页
We use the method of wavelet transform to analyze the time series of the Earth's rotation rate of the EOP (IERS) C04. The result shows that the seasonal (annual and semiannual) variation of the length-of-day (LO... We use the method of wavelet transform to analyze the time series of the Earth's rotation rate of the EOP (IERS) C04. The result shows that the seasonal (annual and semiannual) variation of the length-of-day (LOD) has temporal variability in its period length and amplitude. During 1965.0-2001.0, the periods of the semiannual and annual components varied mainly from 175-day to 190-day and from 360-day to 370-day, respectively; while their amplitudes varied by more than 0.2 ms and 0.1 ms, respectively. Analyzing the axial component of atmospheric angular momentum (AAM) during this period, we have found that time-variations of period lengths and amplitudes also exist in the seasonal oscillations of the axial AAM and are in good consistency with those of the seasonal LOD change. The time variation of the axial AAM can explain largely the change of the LOD on seasonal scales. 展开更多
关键词 Earth rotation -- seasonal variation -- wavelet transform
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A brief review of the development and optimization of the three-dimensional magnetic configuration system in the J-TEXT tokamak
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作者 Zhonghe JIANG Yonghua DING +3 位作者 Bo RAO Nengchao WANG Yangbo LI Jie HUANG 《Plasma Science and Technology》 SCIE EI CAS CSCD 2022年第12期166-171,共6页
The three-dimensional(3D) magnetic configuration system in the J-TEXT tokamak has featured in many experimental studies.The system mainly consists of three subsystems:the static resonant magnetic perturbation(SRMP) sy... The three-dimensional(3D) magnetic configuration system in the J-TEXT tokamak has featured in many experimental studies.The system mainly consists of three subsystems:the static resonant magnetic perturbation(SRMP) system,the dynamic resonant magnetic perturbation(DRMP) system and the helical coil system.The SRMP coil system consist of two kinds of coils,i.e.three six-loop coils and two five-loop coils.It can suppress tearing modes with a moderate strength,and may also cause mode locking with larger amplitude.The DRMP coil system consists of 12 single-turn saddle coils(DRMP1) and 12 double-turn saddle coils(DRMP2).Its magnetic field can be rotated at a few kHz,leading to either acceleration or deceleration of the tearing mode velocity and the plasma rotation.The helical coil system consists of two closed coils,and is currently under construction to provide external rotational transform in J-TEXT.The 3D magnetic configuration system can suppress tearing modes,preventing and avoiding the occurrence of major disruption. 展开更多
关键词 tearing mode resonant magnetic perturbation external rotational transform plasma stability J-TEXT tokamak
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3D Reconstruction and Animation of Brain MRI Images Based on Matlab
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作者 Hong Dai 《Modern Electronic Technology》 2022年第2期1-4,共4页
The following algorithms are proposed and realized by MATLAB programming based on the brain MRI images:(1)The 3D surface of the brain is reconstructed using MC algorithm.(2)A rotate animation of the brain is created a... The following algorithms are proposed and realized by MATLAB programming based on the brain MRI images:(1)The 3D surface of the brain is reconstructed using MC algorithm.(2)A rotate animation of the brain is created and displayed by 3D rotate transformation and animation functions of Matlab.Result shows that the algorithm can show the brain accurately and quickly,takes up less space in memory. 展开更多
关键词 MATLAB 3D reconsruction 3D rotation transformation ANIMATION
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Orthogonal transformation operation theorem of a spatial universal uniform rotating magnetic field and its application in capsule endoscopy 被引量:10
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作者 ZHANG YongShun YU ZiChun +2 位作者 YANG HuiYuan HUANG YunKui CHEN Jun 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2017年第6期854-864,共11页
According to the anti-phase sine current superposition theorem, the orientation, the magnetic flux density, the angular speed and the rotational direction of the spatial universal rotating magnetic field (SURMF) can... According to the anti-phase sine current superposition theorem, the orientation, the magnetic flux density, the angular speed and the rotational direction of the spatial universal rotating magnetic field (SURMF) can be controlled within the tri-axial orthogonal square Helmholtz coils (TOSHC). Nevertheless, three coupling direction angles of the normal vector of the SURMF in the Descartes coordinate system cannot be separately controlled, thus the adjustment of the orientation of the SURMF is difficult and the flexibility of the robotic posture control is restricted. For the dimension reduction and the decoupling of control variables, the orthogonal transformation operation theorem of the SURMF is proposed based on two independent rotation angular variables, which employs azimuth and altitude angles as two variables of the three-phase sine current superposition formula derived by the orthogonal rotation inverse transformation. Then the unique control rules of the orientation and the rotational direction of the SURMF are generalized in each spatial quadrant, thus the scanning of the normal vector of the SURMF along the horizontal or vertical direction can be achieved through changing only one variable, which simplifies the control process of the orientation of the SURMF greatly. To validate its feasibility and maneuverability, experiments were conducted in the animal intestine utilizing the innovative dual hemisphere capsule robot (DHCR) with active and passive modes. It was demonstrated that the posture adjustment and the steering rolling locomotion of the DHCR can be realized through single variable control, thus the orthogonal transformation operation theorem makes the control of the orientation of the SURMF convenient and flexible significantly. This breakthrough will lay a foundation for the human-machine interaction control of the SURMF. 展开更多
关键词 dual hemisphere capsule robot (DHCR) spatial universal rotating magnetic field (SURMF) orthogonal transformation operation variable decoupling
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Method for Workspace Calculation of 6R Serial Manipulator Based on Surface Enveloping and Overlaying 被引量:3
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作者 王宣银 丁渊明 《Journal of Shanghai Jiaotong university(Science)》 EI 2010年第5期556-562,共7页
Aiming at the workspace calculation problem of multi-joint serial manipulators,a surface enveloping and overlaying (SEO) method is presented to identify and visualize the manipulator workspace.The SEO method is compos... Aiming at the workspace calculation problem of multi-joint serial manipulators,a surface enveloping and overlaying (SEO) method is presented to identify and visualize the manipulator workspace.The SEO method is composed of two stages:the first stage is to choose reference points of the manipulator and calculate their boundary surfaces using the nth enveloping method;the second stage is to overlay these boundary surfaces to identify the final workspace.The SEO method is basically a combination of the analytic method and the numerical method.By delineating the graphic representation of the workspace step by step,the SEO method is easy to analyze the existence and the shape of voids and holes.The basic theory of the SEO method and formulas for workspace calculation are presented based on a 6R serial manipulator.By showing the workspace calculation results,the SEO method is proved working correctly. 展开更多
关键词 MANIPULATOR WORKSPACE homogeneous transformation matrix (HTM) rotation transformation matrix (RTM)
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New Wavelet Theory and Application in Nondestructive Testing 被引量:1
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作者 张秀峰 施克仁 郑立男 《Tsinghua Science and Technology》 SCIE EI CAS 2004年第5期565-569,共5页
A new ultrasound signal processing model that provides fast real-time performance was devel- oped. The model is based on the “rotation angle series fast wavelet transform” algorithm developed for real- time digita... A new ultrasound signal processing model that provides fast real-time performance was devel- oped. The model is based on the “rotation angle series fast wavelet transform” algorithm developed for real- time digital signal processing. Instead of the traditional convolution-based algorithms, the algorithm uses a cascaded structure which can be quickly implemented on digital signal processors. The algorithm runs twice as fast as and is more flexible than the fast wavelet transform, and is applicable for multi-channel and phased array ultrasound systems. By using this algorithm, multi-channel ultrasound systems, including phased array ultrasound systems can have less complex software and hardware designs, lower cost, smaller size, and especially more powerful functions. 展开更多
关键词 WAVELET rotation angle series rotation angle series fast wavelet transform nondestructive testing ULTRASOUND
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Efficient coherent detection of maneuvering targets based on location rotation transform and non-uniform fast Fourier transform
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作者 Ke JIN Tao LAI +2 位作者 Yan-li QI Jie HUANG Yong-jun ZHAO 《Frontiers of Information Technology & Electronic Engineering》 SCIE EI CSCD 2020年第8期1251-1266,共16页
Long-term coherent integration can remarkably improve the ability of detection and motion parameter estimation of radar for maneuvering targets.However,the linear range migration,quadratic range migration(QRM),and Dop... Long-term coherent integration can remarkably improve the ability of detection and motion parameter estimation of radar for maneuvering targets.However,the linear range migration,quadratic range migration(QRM),and Doppler frequency migration within the coherent processing interval seriously degrade the detection and estimation performance.Therefore,an efficient and noise-resistant coherent integration method based on location rotation transform(LRT)and non-uniform fast Fourier transform(NuFFT)is proposed.QRM is corrected by the second-order keystone transform.Using the relationship between the rotation angle and Doppler frequency,a novel phase compensation function is constructed.Motion parameters can be rapidly estimated by LRT and NuFFT.Compared with several representative algorithms,the proposed method achieves a nearly ideal detection performance with low computational cost.Finally,experiments based on measured radar data are conducted to verify the proposed algorithm. 展开更多
关键词 Coherent integration Maneuvering target Parameter estimation Location rotation transform(LRT) Non-uniform fast Fourier transform(NuFFT)
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