Flower-like copper foam Co_(3)O_(4) catalysts(Co_(3)O_(4)/CF) were prepared by hydrothermal method.The crystalline structure and microscopic morphology of the prepared samples were characterized by using X-ray diffrac...Flower-like copper foam Co_(3)O_(4) catalysts(Co_(3)O_(4)/CF) were prepared by hydrothermal method.The crystalline structure and microscopic morphology of the prepared samples were characterized by using X-ray diffractometer(XRD) and scanning electron microscope(SEM),and the electrochemical properties were investigated by an electrochemical workstation.The experimental results show that the Co_(3)O_(4) catalysts are successfully prepared on the foamed copper support by hydrothermal method,and the material’s morphology is mainly flower cluster.When the current density is 10 mA·cm^(-2),the overpotential value of the Co_(3)O_(4)/CF catalyst is 141 mV,lower than that of blank support.The electrochemical impedance(EIS) spectrum shows that the R_(ct )value of the Co_(3)O_(4)/CF catalyst decreases,and the Coulomb curves of double-layer show that the electrochemically active area of the Co_(3)O_(4)/CF catalyst efficiently increases compared with that of the blank support.Therefore,the as-obtained Co_(3)O_(4)/CF catalyst exhibits a good hydrogen evolution rate,showing great applicability potential in the catalytic electrolysis of water for hydrogen production.展开更多
The development of nanoelectronics and nanotechnologies has been boosted significantly by the emergence of 2D materials because of their atomic thickness and peculiar properties,and developing a universal,precise patte...The development of nanoelectronics and nanotechnologies has been boosted significantly by the emergence of 2D materials because of their atomic thickness and peculiar properties,and developing a universal,precise patterning technology for single-layer 2D materials is critical for assembling nanodevices.Demonstrated here is a nanomachining technique using electrical breakdown by an AFM tip to fabricate nanopores,nanostrips,and other nanostructures on demand.This can be achieved by voltage scanning or applying a constant voltage while moving the tip.By measuring the electrical current,the formation process on single-layer materials was shown quantitatively.The present results provide evidence of successful pattern fabrication on single-layer MoS2,boron nitride,and graphene,although further confirmation is still needed.The proposed method holds promise as a general nanomachining technology for the future.展开更多
We study the above-threshold ionization(ATI)process of atoms exposed to fundamental and high-frequency lasers with arbitrary ellipticity by applying the frequency-domain theory.It is found that the angular-resolved AT...We study the above-threshold ionization(ATI)process of atoms exposed to fundamental and high-frequency lasers with arbitrary ellipticity by applying the frequency-domain theory.It is found that the angular-resolved ATI spectrum is sensitive to ellipticities of two lasers and emitted angles of the photoelectron.Particularly for the photon energy of the highfrequency laser more than atomic ionization potential,the width of plateau tends to a constant with increasing ellipticity of fundamental field,the dip structure disappears with increasing ellipticity of the high-frequency field.With the help of the quantum channel analysis,it is shown that the angular distribution depends mainly on the ellipticity of high-frequency field in the case that its frequency is high.Moreover,one can see that the maximal and minimal energies in quantum numerical results are in good agreement with the classical prediction.Our investigation may provide theoretical support for experimental research on polarization control of ionization in elliptically polarized two-color laser fields.展开更多
To alleviate the performance deterioration caused by dynamic stall of a wind turbine airfoil,the flow control by a microsecond-pulsed dielectric barrier discharge(MP-DBD) actuator on the dynamic stall of a periodicall...To alleviate the performance deterioration caused by dynamic stall of a wind turbine airfoil,the flow control by a microsecond-pulsed dielectric barrier discharge(MP-DBD) actuator on the dynamic stall of a periodically pitching NACA0012 airfoil was investigated experimentally.Unsteady pressure measurements with high temporal accuracy were employed in this study,and the unsteady characteristics of the boundary layer were investigated by wavelet packet analysis and the moving root mean square method based on the acquired pressure.The experimental Mach number was 0.2,and the chord-based Reynolds number was 870 000.The dimensionless actuation frequencies F+ were chosen to be 0.5,1,2,and 3,respectively.For the light dynamic regime,the MP-DBD plasma actuator plays the role of suppressing flow separation from the trial edge and accelerating the flow reattachment due to the high-momentum freestream flow being entrained into the boundary layer.Meanwhile,actuation effects were promoted with the increasing dimensionless actuation frequency F+.The control effects of the deep dynamic stall were to delay the onset and reduce the strength of the dynamic stall vortex due to the accumulating vorticity near the leading edge being removed by the induced coherent vortex structures.The laminar fluctuation and Kelvin-Helmholtz(K-H) instabilities of transition and relaminarization were also mitigated by the MP-DBD actuation,and the alleviated K-H rolls led to the delay of the transition onset and earlier laminar reattachment,which improved the hysteresis effect of the dynamic stall.For the controlled cases of F+=2,and F+=3,the laminar fluctuation was replaced by relatively low frequency band disturbances corresponding to the harmonic responses of the MP-DBD actuation frequency.展开更多
A Mg-6Zn-3Gd(mass fraction,%) alloy,noted as ZG63,was coated by different micro-arc oxidation(MAO) processes,and the coating structure and corrosion resistance of the alloy were studied using scanning electron microsc...A Mg-6Zn-3Gd(mass fraction,%) alloy,noted as ZG63,was coated by different micro-arc oxidation(MAO) processes,and the coating structure and corrosion resistance of the alloy were studied using scanning electron microscopy(SEM),glancing angle X-ray diffractometry(GAXRD) and various electrochemical methods.The micro-arc oxidation process consists of three stages and corresponds with different coating structures.In the initial stage,the coating thickness is linearly increased and is controlled by electrochemical polarization.In the second stage,the coating grows mainly inward and accords with parabolic regularity.In the third stage,the loose coating forms and is controlled by local arc light.The looser coating is mainly composed of MgSiO3 and the compact coating is mainly composed of MgO.From micro-arc oxidation stage to local arc light stage,the corrosion resistance of the coated alloy firstly increases and then decreases.The satisfied corrosion resistance corresponds to the coating time ranging from 6 to10 min.展开更多
Feature extraction of symmetrical triangular linear frequency modulation continuous wave (LFM- CW) signal is studied. Combined with its peculiar charaeteristics, a novel algorithm based on Wigner-Hough transform (...Feature extraction of symmetrical triangular linear frequency modulation continuous wave (LFM- CW) signal is studied. Combined with its peculiar charaeteristics, a novel algorithm based on Wigner-Hough transform (WHT) is presented for the deteetion and parameter estimation of this type of waveform. The initial frequency and chirp rate of each segment of this wave are estimated, and the peak-value searching steps in the parameter spaee is given. Compared with Wigner-Ville distribution (WVD), Pseudo-Wigner-Ville distri- bution (PWD) and Smoothed-Peseudo-Wigner-Ville distribution (SPWD), WHT has proven itself to be the best method for feature extraetion of symmetrical triangular LFMCW signal. In the end, Monte-Carlo simulations under different SNRs are earried out, with validating results on this method.展开更多
Distinguishing close chirp-rates of different linear frequency modulation (LFM) signals under concentrated and complicated signal environment was studied. Firstly, detection and parameter estimation of multi-compone...Distinguishing close chirp-rates of different linear frequency modulation (LFM) signals under concentrated and complicated signal environment was studied. Firstly, detection and parameter estimation of multi-component LFM signal were used by discrete fast fractional Fourier transform (FrFT). Then the expression of chirp-rate resolution in fractional Fourier domain (FrFD) was deduced from discrete normalize time-frequency distribution, when multi-component LFM signal had only one center frequency. Furthermore, the detail influence of the sampling time, sampling frequency and chirp-rate upon the resolution was analyzed by partial differential equation. Simulation results and analysis indicate that increasing the sampling time can enhance the resolution, but the influence of the sampling frequency can he omitted. What's more, in multi-component LFM signal, the chirp-rate resolution of FrFT is no less than a minimal value, and it mainly dependent on the biggest value of chirp-rates, with which it has an approximately positive exponential relationship.展开更多
This paper describes a new phenomenon of acoustic streaming which takes place when a Helmholtz resonator is excited by an inside sound source with resonant frequency,and takes the form of a strong turbulent jet.The fl...This paper describes a new phenomenon of acoustic streaming which takes place when a Helmholtz resonator is excited by an inside sound source with resonant frequency,and takes the form of a strong turbulent jet.The flow visualizations,hot wire and LDV measurements are combined to investigate the process of acoustic streaming.It is found that this kind of acoustic streaming results from the contribution of Reynolds stress.展开更多
A class of generalized Cohen-Grossberg neural networks(CGNNs) with variable de- lays are investigated. By introducing a new type of Lyapunov functional and applying the homeomorphism theory and inequality technique,...A class of generalized Cohen-Grossberg neural networks(CGNNs) with variable de- lays are investigated. By introducing a new type of Lyapunov functional and applying the homeomorphism theory and inequality technique, some new conditions axe derived ensuring the existence and uniqueness of the equilibrium point and its global exponential stability for CGNNs. These results obtained are independent of delays, develop the existent outcome in the earlier literature and are very easily checked in practice.展开更多
Support Vector Machine (SVM) is a machine learning algorithm based on the Statistical Learning Theory (SLT), which can get good classification effects with a few learning samples. SVM represents a new approach to patt...Support Vector Machine (SVM) is a machine learning algorithm based on the Statistical Learning Theory (SLT), which can get good classification effects with a few learning samples. SVM represents a new approach to pattern classification and has been shown to be particularly successful in many fields such as image identification and face recognition. It also provides us with a new method to develop intelligent fault diagnosis. This paper presents an SVM based approach for fault diagnosis of rolling bearings. Experimentation with vibration signals of bearing was conducted. The vibration signals acquired from the bearings were directly used in the calculating without the preprocessing of extracting its features. Compared with the Artificial Neural Network (ANN) based method, the SVM based method has desirable advantages. Also a multi-fault SVM classifier based on binary clas- sifier is constructed for gear faults in this paper. Other experiments with gear fault samples showed that the multi-fault SVM classifier has good classification ability and high efficiency in mechanical system. It is suitable for on line diagnosis for mechanical system.展开更多
Helical anchors are commonly used in Brazil for guyed transmission towers subjected to static and cyclic wind loads.In most cases,these anchors are installed in tropical residual soil,a micro-structured material in wh...Helical anchors are commonly used in Brazil for guyed transmission towers subjected to static and cyclic wind loads.In most cases,these anchors are installed in tropical residual soil,a micro-structured material in which the shear strength is provided by soil bonding.During installation of a helical anchor,as the helical plate moves downward into the ground,the soil penetrated is sheared and displaced.Consequently,in this type of soil,anchor installation affects the soil shear strength significantly associated with a bonded structure.However,the cyclic responses of helical anchors in this type of structured soils are rarely reported.To address this problem,tests were conducted in a Brazilian residual soil to investigate the monotonic,cyclic and post-cyclic performances of single-helix anchors.Field tests used two instrumented single-helix anchors installed in this typical residual soil of sandstone,which is frequently observed in large areas in the southern Brazil.The testing results indicate that the disturbance caused by the anchor installation affected the monotonic uplift performance markedly.The results of cyclic loading tests also show no significant degradation of helix bearing resistance and reduced displacement accumulation with increasing load cycles.This is perhaps due to the soil improvement caused by previous loading,which then increases the stiffness response of the anchor.展开更多
In order to solve emitter recognition problems in a practical reconnaissance environment, attribute mathematics is introduced. The basic concepts and theory of attribute set and attribute measure are described i n det...In order to solve emitter recognition problems in a practical reconnaissance environment, attribute mathematics is introduced. The basic concepts and theory of attribute set and attribute measure are described i n detail. A new attribute recognition method based on attribute measure is prese nted in this paper. Application example is given, which demonstrates this new me thod is accurate and effective. Moreover, computer simulation for recognizing th e emitter purpose is selected, and compared with classical statistical pattern r ecognition through simulation. The excellent experimental results demonstrate t hat this is a brand-new attribute recognition method as compared to existing st atistical pattern recognition techniques.展开更多
Traditional range-dependency compensation space time adaptive processing(STAP)methods usually involve aligning the clutter spectrums in a certain point to reduce the clutter non-homogeneity.A novel compensation STAP m...Traditional range-dependency compensation space time adaptive processing(STAP)methods usually involve aligning the clutter spectrums in a certain point to reduce the clutter non-homogeneity.A novel compensation STAP method is proposed as an improved Doppler warping(DW)method for airborne radar with non-sidelooking radar.This method facilitates DW method to bring clutter spectrum of different range gates together in the mainlobe and subsequently compensation to accomplish space angle of different range gates alignment at multiple Doppler bins.Simulation results show that the proposed method can further reduce the clutter non-homogeneity of non-sidelooking array and significantly outperform traditional algorithms with only a little increase of the computation load.展开更多
Shoot efficiency is one of the most important evaluation indexes of the operation efficiency of weapon system.In this paper,based on definitions of the probability and the expected number of missed attacking missiles,...Shoot efficiency is one of the most important evaluation indexes of the operation efficiency of weapon system.In this paper,based on definitions of the probability and the expected number of missed attacking missiles,the expected numbers of anti-missiles and attacking missiles hit by single anti-missile,fusillade mechanism of multi-missile is analyzed systematically.The weapon operation efficiency in various engagement patterns is also studied.The results show that double missiles fusillade is the most feasible manner for increasing the weapon operation efficiency.展开更多
基金Funded by the National Natural Science Foundation of China(No.51474170)the Foundation of Shaanxi Educational Committee(No.17JK0395)the Xi’an Science and Technology Committee Program(No.GXYD9.2)。
文摘Flower-like copper foam Co_(3)O_(4) catalysts(Co_(3)O_(4)/CF) were prepared by hydrothermal method.The crystalline structure and microscopic morphology of the prepared samples were characterized by using X-ray diffractometer(XRD) and scanning electron microscope(SEM),and the electrochemical properties were investigated by an electrochemical workstation.The experimental results show that the Co_(3)O_(4) catalysts are successfully prepared on the foamed copper support by hydrothermal method,and the material’s morphology is mainly flower cluster.When the current density is 10 mA·cm^(-2),the overpotential value of the Co_(3)O_(4)/CF catalyst is 141 mV,lower than that of blank support.The electrochemical impedance(EIS) spectrum shows that the R_(ct )value of the Co_(3)O_(4)/CF catalyst decreases,and the Coulomb curves of double-layer show that the electrochemically active area of the Co_(3)O_(4)/CF catalyst efficiently increases compared with that of the blank support.Therefore,the as-obtained Co_(3)O_(4)/CF catalyst exhibits a good hydrogen evolution rate,showing great applicability potential in the catalytic electrolysis of water for hydrogen production.
基金supported by the National Natural Science Foundation of China(Grant Nos.12075191,12388101,and 12241201)the Fundamental Research Funds for the Central Universities(Grant No.D5000230120)the Natural Science Basic Research Program of Shaanxi Province(Grant No.2023-JC-YB-541).
文摘The development of nanoelectronics and nanotechnologies has been boosted significantly by the emergence of 2D materials because of their atomic thickness and peculiar properties,and developing a universal,precise patterning technology for single-layer 2D materials is critical for assembling nanodevices.Demonstrated here is a nanomachining technique using electrical breakdown by an AFM tip to fabricate nanopores,nanostrips,and other nanostructures on demand.This can be achieved by voltage scanning or applying a constant voltage while moving the tip.By measuring the electrical current,the formation process on single-layer materials was shown quantitatively.The present results provide evidence of successful pattern fabrication on single-layer MoS2,boron nitride,and graphene,although further confirmation is still needed.The proposed method holds promise as a general nanomachining technology for the future.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.12104285,12074240,12204135,12374260,12264013,12204136,92250303,and 12074418)the Guangdong Basicand Applied Basic Research Foundation (Grant No.2022A1515011742)+5 种基金the Special Scientific Research Program supported by the Shaanxi Education Department (Grant No.22JK0423)the Natural Science Basic Research Program of Shaanxi Province of China (Grant Nos.2023-JC-QN-0085 and 2023-JC-QN-0267)the Hainan Provincial Natural Science Foundation of China (Grant Nos.122CXTD504,123MS002,123QN179,123QN180,and 122QN217)the Sino-German Mobility Programme (Grant No.M-0031)the Xi’an Aeronautical Institute 2023 Innovation and Entrepreneurship Training Program for college students (Grant No.S202311736036)the Course Ideological and Political Education Program (Grant No.23ZLGC5030)。
文摘We study the above-threshold ionization(ATI)process of atoms exposed to fundamental and high-frequency lasers with arbitrary ellipticity by applying the frequency-domain theory.It is found that the angular-resolved ATI spectrum is sensitive to ellipticities of two lasers and emitted angles of the photoelectron.Particularly for the photon energy of the highfrequency laser more than atomic ionization potential,the width of plateau tends to a constant with increasing ellipticity of fundamental field,the dip structure disappears with increasing ellipticity of the high-frequency field.With the help of the quantum channel analysis,it is shown that the angular distribution depends mainly on the ellipticity of high-frequency field in the case that its frequency is high.Moreover,one can see that the maximal and minimal energies in quantum numerical results are in good agreement with the classical prediction.Our investigation may provide theoretical support for experimental research on polarization control of ionization in elliptically polarized two-color laser fields.
基金supported by National Natural Science Foundation of China(Nos.12172299 and 1190021162)。
文摘To alleviate the performance deterioration caused by dynamic stall of a wind turbine airfoil,the flow control by a microsecond-pulsed dielectric barrier discharge(MP-DBD) actuator on the dynamic stall of a periodically pitching NACA0012 airfoil was investigated experimentally.Unsteady pressure measurements with high temporal accuracy were employed in this study,and the unsteady characteristics of the boundary layer were investigated by wavelet packet analysis and the moving root mean square method based on the acquired pressure.The experimental Mach number was 0.2,and the chord-based Reynolds number was 870 000.The dimensionless actuation frequencies F+ were chosen to be 0.5,1,2,and 3,respectively.For the light dynamic regime,the MP-DBD plasma actuator plays the role of suppressing flow separation from the trial edge and accelerating the flow reattachment due to the high-momentum freestream flow being entrained into the boundary layer.Meanwhile,actuation effects were promoted with the increasing dimensionless actuation frequency F+.The control effects of the deep dynamic stall were to delay the onset and reduce the strength of the dynamic stall vortex due to the accumulating vorticity near the leading edge being removed by the induced coherent vortex structures.The laminar fluctuation and Kelvin-Helmholtz(K-H) instabilities of transition and relaminarization were also mitigated by the MP-DBD actuation,and the alleviated K-H rolls led to the delay of the transition onset and earlier laminar reattachment,which improved the hysteresis effect of the dynamic stall.For the controlled cases of F+=2,and F+=3,the laminar fluctuation was replaced by relatively low frequency band disturbances corresponding to the harmonic responses of the MP-DBD actuation frequency.
文摘A Mg-6Zn-3Gd(mass fraction,%) alloy,noted as ZG63,was coated by different micro-arc oxidation(MAO) processes,and the coating structure and corrosion resistance of the alloy were studied using scanning electron microscopy(SEM),glancing angle X-ray diffractometry(GAXRD) and various electrochemical methods.The micro-arc oxidation process consists of three stages and corresponds with different coating structures.In the initial stage,the coating thickness is linearly increased and is controlled by electrochemical polarization.In the second stage,the coating grows mainly inward and accords with parabolic regularity.In the third stage,the loose coating forms and is controlled by local arc light.The looser coating is mainly composed of MgSiO3 and the compact coating is mainly composed of MgO.From micro-arc oxidation stage to local arc light stage,the corrosion resistance of the coated alloy firstly increases and then decreases.The satisfied corrosion resistance corresponds to the coating time ranging from 6 to10 min.
基金Sponsored by the National Natural Science Foundation of China (6023201060572094)the National Natural Science Foundation of China for Distinguished Young Scholars (60625104)
文摘Feature extraction of symmetrical triangular linear frequency modulation continuous wave (LFM- CW) signal is studied. Combined with its peculiar charaeteristics, a novel algorithm based on Wigner-Hough transform (WHT) is presented for the deteetion and parameter estimation of this type of waveform. The initial frequency and chirp rate of each segment of this wave are estimated, and the peak-value searching steps in the parameter spaee is given. Compared with Wigner-Ville distribution (WVD), Pseudo-Wigner-Ville distri- bution (PWD) and Smoothed-Peseudo-Wigner-Ville distribution (SPWD), WHT has proven itself to be the best method for feature extraetion of symmetrical triangular LFMCW signal. In the end, Monte-Carlo simulations under different SNRs are earried out, with validating results on this method.
基金Sponsored by the National Natural Science Foundation of China (60232010 ,60572094)the National Science Foundation of China for Distin-guished Young Scholars (60625104)
文摘Distinguishing close chirp-rates of different linear frequency modulation (LFM) signals under concentrated and complicated signal environment was studied. Firstly, detection and parameter estimation of multi-component LFM signal were used by discrete fast fractional Fourier transform (FrFT). Then the expression of chirp-rate resolution in fractional Fourier domain (FrFD) was deduced from discrete normalize time-frequency distribution, when multi-component LFM signal had only one center frequency. Furthermore, the detail influence of the sampling time, sampling frequency and chirp-rate upon the resolution was analyzed by partial differential equation. Simulation results and analysis indicate that increasing the sampling time can enhance the resolution, but the influence of the sampling frequency can he omitted. What's more, in multi-component LFM signal, the chirp-rate resolution of FrFT is no less than a minimal value, and it mainly dependent on the biggest value of chirp-rates, with which it has an approximately positive exponential relationship.
文摘This paper describes a new phenomenon of acoustic streaming which takes place when a Helmholtz resonator is excited by an inside sound source with resonant frequency,and takes the form of a strong turbulent jet.The flow visualizations,hot wire and LDV measurements are combined to investigate the process of acoustic streaming.It is found that this kind of acoustic streaming results from the contribution of Reynolds stress.
基金Supported by the Distinguished Expert Science Foundation of Naval Aeronautical Engineering Institutethe Younger Foundation of Yantai University (SX06Z9)
文摘A class of generalized Cohen-Grossberg neural networks(CGNNs) with variable de- lays are investigated. By introducing a new type of Lyapunov functional and applying the homeomorphism theory and inequality technique, some new conditions axe derived ensuring the existence and uniqueness of the equilibrium point and its global exponential stability for CGNNs. These results obtained are independent of delays, develop the existent outcome in the earlier literature and are very easily checked in practice.
基金National Natural Science Foundation of China under Grant No.10371070the Special Found for Major Specialities of Shanghai Education CommitteeChina Postdoctoral Science Foundation
基金Project (No. 0424260002) supported by the Natural ScienceFoundation of Henan Province, China
文摘Support Vector Machine (SVM) is a machine learning algorithm based on the Statistical Learning Theory (SLT), which can get good classification effects with a few learning samples. SVM represents a new approach to pattern classification and has been shown to be particularly successful in many fields such as image identification and face recognition. It also provides us with a new method to develop intelligent fault diagnosis. This paper presents an SVM based approach for fault diagnosis of rolling bearings. Experimentation with vibration signals of bearing was conducted. The vibration signals acquired from the bearings were directly used in the calculating without the preprocessing of extracting its features. Compared with the Artificial Neural Network (ANN) based method, the SVM based method has desirable advantages. Also a multi-fault SVM classifier based on binary clas- sifier is constructed for gear faults in this paper. Other experiments with gear fault samples showed that the multi-fault SVM classifier has good classification ability and high efficiency in mechanical system. It is suitable for on line diagnosis for mechanical system.
基金financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior, Brazil (Finance Code 001)the USP-COFECUB Project(Grant No. UcMa 132/12)
文摘Helical anchors are commonly used in Brazil for guyed transmission towers subjected to static and cyclic wind loads.In most cases,these anchors are installed in tropical residual soil,a micro-structured material in which the shear strength is provided by soil bonding.During installation of a helical anchor,as the helical plate moves downward into the ground,the soil penetrated is sheared and displaced.Consequently,in this type of soil,anchor installation affects the soil shear strength significantly associated with a bonded structure.However,the cyclic responses of helical anchors in this type of structured soils are rarely reported.To address this problem,tests were conducted in a Brazilian residual soil to investigate the monotonic,cyclic and post-cyclic performances of single-helix anchors.Field tests used two instrumented single-helix anchors installed in this typical residual soil of sandstone,which is frequently observed in large areas in the southern Brazil.The testing results indicate that the disturbance caused by the anchor installation affected the monotonic uplift performance markedly.The results of cyclic loading tests also show no significant degradation of helix bearing resistance and reduced displacement accumulation with increasing load cycles.This is perhaps due to the soil improvement caused by previous loading,which then increases the stiffness response of the anchor.
文摘In order to solve emitter recognition problems in a practical reconnaissance environment, attribute mathematics is introduced. The basic concepts and theory of attribute set and attribute measure are described i n detail. A new attribute recognition method based on attribute measure is prese nted in this paper. Application example is given, which demonstrates this new me thod is accurate and effective. Moreover, computer simulation for recognizing th e emitter purpose is selected, and compared with classical statistical pattern r ecognition through simulation. The excellent experimental results demonstrate t hat this is a brand-new attribute recognition method as compared to existing st atistical pattern recognition techniques.
基金Supported by the National Natural Science Foundation of China(61201459,61071165)the National Defense Basic Science Research Scheme(B2520110008)the Program for New Century Excellent Talents in University(NCET-09-0069)
文摘Traditional range-dependency compensation space time adaptive processing(STAP)methods usually involve aligning the clutter spectrums in a certain point to reduce the clutter non-homogeneity.A novel compensation STAP method is proposed as an improved Doppler warping(DW)method for airborne radar with non-sidelooking radar.This method facilitates DW method to bring clutter spectrum of different range gates together in the mainlobe and subsequently compensation to accomplish space angle of different range gates alignment at multiple Doppler bins.Simulation results show that the proposed method can further reduce the clutter non-homogeneity of non-sidelooking array and significantly outperform traditional algorithms with only a little increase of the computation load.
基金the National Science Foundation of China (70671105)
文摘Shoot efficiency is one of the most important evaluation indexes of the operation efficiency of weapon system.In this paper,based on definitions of the probability and the expected number of missed attacking missiles,the expected numbers of anti-missiles and attacking missiles hit by single anti-missile,fusillade mechanism of multi-missile is analyzed systematically.The weapon operation efficiency in various engagement patterns is also studied.The results show that double missiles fusillade is the most feasible manner for increasing the weapon operation efficiency.