The adaptive digital beamforming technique in the space-polarization domain suppresses the interference with forming the coupling nulls of space and polarization domain.When there is the interference in mainlobe,it wi...The adaptive digital beamforming technique in the space-polarization domain suppresses the interference with forming the coupling nulls of space and polarization domain.When there is the interference in mainlobe,it will cause serious mainlobe distortion,that the target detection suffers from.To overcome this problem and make radar cope with the complex multiple interferences scenarios,we propose a multiple mainlobe and/or sidelobe interferences suppression method for dual polarization array radar.Specifically,the proposed method consists of a signal preprocessing based on the proposed angle estimation with degree of polarization(DoP),and a filtering criterion based on the proposed linear constraint.The signal preprocessing provides the accurate estimated parameters of the interference,which contributes to the criterion for null-decoupling in the space-polarization domain of mainlobe.The proposed method can reduce the mainlobe distortion in the space-polarization domain while suppressing the multiple mainlobe and/or sidelobe interferences.The effectiveness of the proposed method is verified by simulations.展开更多
The occurrence of arc interference between the adjacent arcs becomes an important problem in triple-electrode high speed CO2 fillet welding. To clarify this problem, polarities effects on arc interference were investi...The occurrence of arc interference between the adjacent arcs becomes an important problem in triple-electrode high speed CO2 fillet welding. To clarify this problem, polarities effects on arc interference were investigated. The experimental results and theoretical analysis showed that the reverse magnetic field generated by the middle wire （ DCEN or DCEP ） decreased the arc deflection due to arc interference. The average arc voltage fluctuations induced by DCEP/DECN/DCEP and DCEN/DCEP/DCEN were smaller than those induced by the other polarities.展开更多
The polarization filter using three orthogonal linear polarization antennas can suppress more disturbances than the polarization filter using two orthogonal linear polarization antennas in HF ground wave radar. But th...The polarization filter using three orthogonal linear polarization antennas can suppress more disturbances than the polarization filter using two orthogonal linear polarization antennas in HF ground wave radar. But the algorithm of the threedimension filter is relatively complicated and not suitable for real-time processing. It can＇t use linear and nonlinear polarization vector translation technique directly. A modified polarization filter which is simple and has same suppressing ability as the three-dimension polarization filter is given. It only has half parameters of the primary one. Some problems about estimation of polarization parameters and selection of disturbances are discussed. A method of holding the phase of radar backscatter signal constantly is put forward so that unstationary disturbance signal can be processed.展开更多
This paper focuses on advanced analysis techniques and design considerations of DC interference generated by HVDC electrodes during normal bipolar and temporary monopolar operations on neighboring metallic utilities, ...This paper focuses on advanced analysis techniques and design considerations of DC interference generated by HVDC electrodes during normal bipolar and temporary monopolar operations on neighboring metallic utilities, with a special emphasis on buried gas and oil pipelines. This study examines the level of pipeline corrosion, the safety status in the vicinity of exposed appurtenances and the impact of DC interference on the integrity of insulating flanges and impressed current cathodic protection (ICCP) systems. Computation results obtained for different soil models show that different soils can lead to completely different DC interference effects. The results and conclusions presented here can be used as a reference to analyze the severity of DC interference on pipelines due to proximate HVDC electrodes.展开更多
A new kind of adaptive polarization filtering algorithm in order to suppress the angle cheating interference for the active guidance radar is presented. The polarization characteristic of the interference is dynamical...A new kind of adaptive polarization filtering algorithm in order to suppress the angle cheating interference for the active guidance radar is presented. The polarization characteristic of the interference is dynamically tracked by using Kalman estimator under variable environments with time. The polarization filter parameters are designed according to the polarization characteristic of the interference, and the polarization filtering is finished in the target cell. The system scheme of adaptive polarization filter is studied and the tracking performance of polarization filter and improvement of angle measurement precision are simulated. The research results demonstrate this technology can effectively suppress the angle cheating interference in guidance radar and is feasible in engineering.展开更多
Visual cryptography is a method of encrypting an image into several encrypted images. Conventional visual cryptography can display only monochrome images. We previously proposed a color visual cryptography method that...Visual cryptography is a method of encrypting an image into several encrypted images. Conventional visual cryptography can display only monochrome images. We previously proposed a color visual cryptography method that uses the interference color of high-order retarder films and encrypts one secret image into two encrypted images. In other words, this method can only encrypt one image at a time. In this paper, we propose a new method that encrypts two color images using interference color.展开更多
Visual cryptography is an encryption method that shares a secret image through several encrypted images. General visual cryptography has no stacking order dependence, and only one image can be decoded regardless of st...Visual cryptography is an encryption method that shares a secret image through several encrypted images. General visual cryptography has no stacking order dependence, and only one image can be decoded regardless of stacking order of encrypted images. We previously reported a color visual cryptography using interference color (or polarization color) of retarder films. The interference color changes depending on the stacking order of retarder films. In this paper, we propose and develop a color visual cryptography that displays two images by changing stacking order of retarder films.展开更多
In this paper,we propose an ultrabroadband chiral metasurface(CMS)composed of S-shaped resonator structures situated between two twisted subwavelength gratings and dielectric substrate.This innovative structure enable...In this paper,we propose an ultrabroadband chiral metasurface(CMS)composed of S-shaped resonator structures situated between two twisted subwavelength gratings and dielectric substrate.This innovative structure enables ultrabroadband and high-efficiency linear polarization(LP)conversion,as well as asymmetric transmission(AT)effect in the microwave region.The enhanced interference effect of the Fabry-Perot-like resonance cavity greatly expands the bandwidth and efficiency of LP conversion and AT effect.Through numerical simulations,it has been revealed that the cross-polarization transmission coefficients for normal forward(-z)and backward(+z)incidence exceed 0.8 in the frequency range of 4.13 to 17.34 GHz,accompanied by a polarization conversion ratio of over 99%.Furthermore,our microwave experimental results validate the consistency among simulation,theory,and measurement.Additionally,we elucidate the distinct characteristics of ultrabroadband LP conversion and significant AT effect through analysis of polarization azimuth rotation and ellipticity angles,total transmittance,AT coefficient,and electric field distribution.The proposed CMS structure shows excellent polarization conversion properties via AT effect and has potential applications in areas such as radar,remote sensing,and satellite communication.展开更多
Some optical fiber hydrophones, such as PGC Mach-Zehnder Interferometer, have a birefringence of single mode optical fibers which induce signal fading. Especially, if two optical beams from the optical arms are orthog...Some optical fiber hydrophones, such as PGC Mach-Zehnder Interferometer, have a birefringence of single mode optical fibers which induce signal fading. Especially, if two optical beams from the optical arms are orthogonal, the interferomic signal can’t be detected at all. Here a new method is introduced. This is to translate the detected phase difference into a linearly polarized angle, then detect it, so that polarization inducing signal fading will be avoided. In theory, this problem is solved. Furthermore, the effect on measurement results from optical source fluctuation becomes little when using the polarization technique.展开更多
The mechanism and characteristics of spectral polarization imaging technique are presented. The present research and developing trend of spectral polarization remote sensing are introduced. A novel method of spectral ...The mechanism and characteristics of spectral polarization imaging technique are presented. The present research and developing trend of spectral polarization remote sensing are introduced. A novel method of spectral polarization imaging technique is discussed, which is based on static intensity modulation adding with double refraction crystal spectrometer. The static intensity modulation consists of two retarders and one polarizer. The double refraction crystal is used to generate interference image. The spectral and four Stokes vectors information can be obtained only by one measurement. The method of static intensity modulation is deduced in detail and is simulated by computer. The spectropolarimeter experimental system is also established in the laboratory. The basic concept of the technique is verified.展开更多
Based on a dual-polarization high-frequency wave radar system, an adaptive system using horizontal antennas for the suppression of the Es layer interference （ELI） is deseribech The data received from the horizontal ...Based on a dual-polarization high-frequency wave radar system, an adaptive system using horizontal antennas for the suppression of the Es layer interference （ELI） is deseribech The data received from the horizontal antennas were correlated with the data received from the Vertically Polarized Antennas （VPAs） to estimate and cancel the interference adaptively in the VPAs. Suppressing the interference after each coherent integration time interval, about 25 dB signal-to-interference ratio is expected with the experimentally derived data.展开更多
当干扰信号的空域和极化域特征与目标信号相似时,采用空极化域联合抗干扰技术在消除干扰的同时也会抑制目标信号,导致干扰对消后信干噪比(signal to interference plus noise ratio,SINR)低于雷达系统需求,从而形成干扰对消盲区。针对...当干扰信号的空域和极化域特征与目标信号相似时,采用空极化域联合抗干扰技术在消除干扰的同时也会抑制目标信号,导致干扰对消后信干噪比(signal to interference plus noise ratio,SINR)低于雷达系统需求,从而形成干扰对消盲区。针对这一现象,通过在空域、极化域与空极化域分别建立交替极化阵列对消盲区模型,推导了对消盲区位置和大小的数学表达式,从而给出了交替极化阵列对消盲区的数学表征方法。进而分析了交替极化阵列对消盲区的分布规律与影响因素,研究发现阵元间距能够显著影响交替极化阵列对消盲区的分布,在相同条件下交替极化阵列对消盲区大于共点极化阵列对消盲区,结果表明交替极化阵列虽然通过减少天线数目降低了设备成本,但增大了阵列的对消盲区。然后,对消盲区模型进行了数值仿真,仿真结果验证了理论分析。最后,利用信道模拟器搭建了实验平台,信道模拟实验测得的对消盲区与理论值基本一致,再次证明了分析结论的有效性。展开更多
基金supported by the National Natural Science Foundation of China(6190149661871385)。
文摘The adaptive digital beamforming technique in the space-polarization domain suppresses the interference with forming the coupling nulls of space and polarization domain.When there is the interference in mainlobe,it will cause serious mainlobe distortion,that the target detection suffers from.To overcome this problem and make radar cope with the complex multiple interferences scenarios,we propose a multiple mainlobe and/or sidelobe interferences suppression method for dual polarization array radar.Specifically,the proposed method consists of a signal preprocessing based on the proposed angle estimation with degree of polarization(DoP),and a filtering criterion based on the proposed linear constraint.The signal preprocessing provides the accurate estimated parameters of the interference,which contributes to the criterion for null-decoupling in the space-polarization domain of mainlobe.The proposed method can reduce the mainlobe distortion in the space-polarization domain while suppressing the multiple mainlobe and/or sidelobe interferences.The effectiveness of the proposed method is verified by simulations.
文摘The occurrence of arc interference between the adjacent arcs becomes an important problem in triple-electrode high speed CO2 fillet welding. To clarify this problem, polarities effects on arc interference were investigated. The experimental results and theoretical analysis showed that the reverse magnetic field generated by the middle wire （ DCEN or DCEP ） decreased the arc deflection due to arc interference. The average arc voltage fluctuations induced by DCEP/DECN/DCEP and DCEN/DCEP/DCEN were smaller than those induced by the other polarities.
文摘The polarization filter using three orthogonal linear polarization antennas can suppress more disturbances than the polarization filter using two orthogonal linear polarization antennas in HF ground wave radar. But the algorithm of the threedimension filter is relatively complicated and not suitable for real-time processing. It can＇t use linear and nonlinear polarization vector translation technique directly. A modified polarization filter which is simple and has same suppressing ability as the three-dimension polarization filter is given. It only has half parameters of the primary one. Some problems about estimation of polarization parameters and selection of disturbances are discussed. A method of holding the phase of radar backscatter signal constantly is put forward so that unstationary disturbance signal can be processed.
文摘This paper focuses on advanced analysis techniques and design considerations of DC interference generated by HVDC electrodes during normal bipolar and temporary monopolar operations on neighboring metallic utilities, with a special emphasis on buried gas and oil pipelines. This study examines the level of pipeline corrosion, the safety status in the vicinity of exposed appurtenances and the impact of DC interference on the integrity of insulating flanges and impressed current cathodic protection (ICCP) systems. Computation results obtained for different soil models show that different soils can lead to completely different DC interference effects. The results and conclusions presented here can be used as a reference to analyze the severity of DC interference on pipelines due to proximate HVDC electrodes.
文摘A new kind of adaptive polarization filtering algorithm in order to suppress the angle cheating interference for the active guidance radar is presented. The polarization characteristic of the interference is dynamically tracked by using Kalman estimator under variable environments with time. The polarization filter parameters are designed according to the polarization characteristic of the interference, and the polarization filtering is finished in the target cell. The system scheme of adaptive polarization filter is studied and the tracking performance of polarization filter and improvement of angle measurement precision are simulated. The research results demonstrate this technology can effectively suppress the angle cheating interference in guidance radar and is feasible in engineering.
文摘Visual cryptography is a method of encrypting an image into several encrypted images. Conventional visual cryptography can display only monochrome images. We previously proposed a color visual cryptography method that uses the interference color of high-order retarder films and encrypts one secret image into two encrypted images. In other words, this method can only encrypt one image at a time. In this paper, we propose a new method that encrypts two color images using interference color.
文摘Visual cryptography is an encryption method that shares a secret image through several encrypted images. General visual cryptography has no stacking order dependence, and only one image can be decoded regardless of stacking order of encrypted images. We previously reported a color visual cryptography using interference color (or polarization color) of retarder films. The interference color changes depending on the stacking order of retarder films. In this paper, we propose and develop a color visual cryptography that displays two images by changing stacking order of retarder films.
文摘In this paper,we propose an ultrabroadband chiral metasurface(CMS)composed of S-shaped resonator structures situated between two twisted subwavelength gratings and dielectric substrate.This innovative structure enables ultrabroadband and high-efficiency linear polarization(LP)conversion,as well as asymmetric transmission(AT)effect in the microwave region.The enhanced interference effect of the Fabry-Perot-like resonance cavity greatly expands the bandwidth and efficiency of LP conversion and AT effect.Through numerical simulations,it has been revealed that the cross-polarization transmission coefficients for normal forward(-z)and backward(+z)incidence exceed 0.8 in the frequency range of 4.13 to 17.34 GHz,accompanied by a polarization conversion ratio of over 99%.Furthermore,our microwave experimental results validate the consistency among simulation,theory,and measurement.Additionally,we elucidate the distinct characteristics of ultrabroadband LP conversion and significant AT effect through analysis of polarization azimuth rotation and ellipticity angles,total transmittance,AT coefficient,and electric field distribution.The proposed CMS structure shows excellent polarization conversion properties via AT effect and has potential applications in areas such as radar,remote sensing,and satellite communication.
文摘Some optical fiber hydrophones, such as PGC Mach-Zehnder Interferometer, have a birefringence of single mode optical fibers which induce signal fading. Especially, if two optical beams from the optical arms are orthogonal, the interferomic signal can’t be detected at all. Here a new method is introduced. This is to translate the detected phase difference into a linearly polarized angle, then detect it, so that polarization inducing signal fading will be avoided. In theory, this problem is solved. Furthermore, the effect on measurement results from optical source fluctuation becomes little when using the polarization technique.
文摘The mechanism and characteristics of spectral polarization imaging technique are presented. The present research and developing trend of spectral polarization remote sensing are introduced. A novel method of spectral polarization imaging technique is discussed, which is based on static intensity modulation adding with double refraction crystal spectrometer. The static intensity modulation consists of two retarders and one polarizer. The double refraction crystal is used to generate interference image. The spectral and four Stokes vectors information can be obtained only by one measurement. The method of static intensity modulation is deduced in detail and is simulated by computer. The spectropolarimeter experimental system is also established in the laboratory. The basic concept of the technique is verified.
文摘Based on a dual-polarization high-frequency wave radar system, an adaptive system using horizontal antennas for the suppression of the Es layer interference （ELI） is deseribech The data received from the horizontal antennas were correlated with the data received from the Vertically Polarized Antennas （VPAs） to estimate and cancel the interference adaptively in the VPAs. Suppressing the interference after each coherent integration time interval, about 25 dB signal-to-interference ratio is expected with the experimentally derived data.
文摘当干扰信号的空域和极化域特征与目标信号相似时,采用空极化域联合抗干扰技术在消除干扰的同时也会抑制目标信号,导致干扰对消后信干噪比(signal to interference plus noise ratio,SINR)低于雷达系统需求,从而形成干扰对消盲区。针对这一现象,通过在空域、极化域与空极化域分别建立交替极化阵列对消盲区模型,推导了对消盲区位置和大小的数学表达式,从而给出了交替极化阵列对消盲区的数学表征方法。进而分析了交替极化阵列对消盲区的分布规律与影响因素,研究发现阵元间距能够显著影响交替极化阵列对消盲区的分布,在相同条件下交替极化阵列对消盲区大于共点极化阵列对消盲区,结果表明交替极化阵列虽然通过减少天线数目降低了设备成本,但增大了阵列的对消盲区。然后,对消盲区模型进行了数值仿真,仿真结果验证了理论分析。最后,利用信道模拟器搭建了实验平台,信道模拟实验测得的对消盲区与理论值基本一致,再次证明了分析结论的有效性。
