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First-Order Symmetry Energy Induced by Neutron-Proton Mass Difference 被引量:1
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作者 董建敏 左维 顾建中 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第10期32-35,共4页
The 1st-order symmetry energy coefficient of nuclear matter induced merely by the neutron-proton (n p) mass difference is derived analytically, which turns out to be completely model-independent. Based on this resul... The 1st-order symmetry energy coefficient of nuclear matter induced merely by the neutron-proton (n p) mass difference is derived analytically, which turns out to be completely model-independent. Based on this result, (npDM) the 1st-order symmetry energy Esym,1 (A) of heavy nuclei such as 2~spb induced by the np mass difference is investigated with the help of a local density approximation combined with the Skyrme energy density functionals. Although /U(npDM) Esym,1 (A) is small compared with the second-order symmetry energy, it cannot be dropped simply for an accurate estimation of nuclear masses as it is still larger than the rms deviation given by some accurate mass formulas. It is therefore suggested that one perhaps needs to distinguish the neutron mass from the proton one in the construction of nuclear density funetionals. 展开更多
关键词 of on as in by first-order Symmetry Energy Induced by Neutron-Proton Mass difference IS
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Numerical Analysis of Upwind Difference Schemes for Two-Dimensional First-Order Hyperbolic Equations with Variable Coefficients 被引量:1
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作者 Yanmeng Sun Qing Yang 《Engineering(科研)》 2021年第6期306-329,共24页
In this paper, we consider the initial-boundary value problem of two-dimensional first-order linear hyperbolic equation with variable coefficients. By using the upwind difference method to discretize the spatial deriv... In this paper, we consider the initial-boundary value problem of two-dimensional first-order linear hyperbolic equation with variable coefficients. By using the upwind difference method to discretize the spatial derivative term and the forward and backward Euler method to discretize the time derivative term, the explicit and implicit upwind difference schemes are obtained respectively. It is proved that the explicit upwind scheme is conditionally stable and the implicit upwind scheme is unconditionally stable. Then the convergence of the schemes is derived. Numerical examples verify the results of theoretical analysis. 展开更多
关键词 Two-Dimensional first-order Hyperbolic Equation Variable Coefficients Upwind difference Schemes Fourier Method Stability and Error Estimation
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Almost Sure Convergence and Complete Convergence for the Weighted Sums of Martingale Differences 被引量:1
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《Wuhan University Journal of Natural Sciences》 CAS 1999年第3期278-284,共7页
Let {(D n, FFFn),n/->1} be a sequence of martingale differences and {a ni, 1≤i≤n,n≥1} be an array of real constants. Almost sure convergence for the row sums ?i = 1n ani D1\sum\limits_{i = 1}^n {a_{ni} D_1 } are... Let {(D n, FFFn),n/->1} be a sequence of martingale differences and {a ni, 1≤i≤n,n≥1} be an array of real constants. Almost sure convergence for the row sums ?i = 1n ani D1\sum\limits_{i = 1}^n {a_{ni} D_1 } are discussed. We also discuss complete convergence for the moving average processes underB-valued martingale differences assumption. 展开更多
关键词 complete convergence almost sure convergence weighted sums martingale differences moving average processes
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Some Properties of the Sum and Geometric Differences of Minkowski 被引量:2
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作者 Mashrabjon Mamatov Jalolxon Nuritdinov 《Journal of Applied Mathematics and Physics》 2020年第10期2241-2255,共15页
The sets of Minkowski algebraic sum and geometric difference are considered. The purpose of the research in this paper is to apply the properties of Minkowski sum and geometric difference to fractional differential ga... The sets of Minkowski algebraic sum and geometric difference are considered. The purpose of the research in this paper is to apply the properties of Minkowski sum and geometric difference to fractional differential games. This paper investigates the geometric properties of the Minkowski algebraic sum and the geometric difference of sets. Various examples are considered that calculate the geometric differences of sets. The results of the research are presented and proved as a theorem. At the end of the article, the results were applied to fractional differential games. 展开更多
关键词 Computational Geometry Algebraic sums Geometric differences
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Study on Color Difference of Color Reproduction of 3D Objects
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作者 GU Chong DENG Yi-qiang 《印刷与数字媒体技术研究》 北大核心 2025年第4期33-38,69,共7页
To investigate the applicability of four commonly used color difference formulas(CIELAB,CIE94,CMC(1:1),and CIEDE2000)in the printing field on 3D objects,as well as the impact of four standard light sources(D65,D50,A,a... To investigate the applicability of four commonly used color difference formulas(CIELAB,CIE94,CMC(1:1),and CIEDE2000)in the printing field on 3D objects,as well as the impact of four standard light sources(D65,D50,A,and TL84)on 3D color difference evaluations,50 glossy spheres with a diameter of 2cm based on the Sailner J4003D color printing device were created.These spheres were centered around the five recommended colors(gray,red,yellow,green,and blue)by CIE.Color difference was calculated according to the four formulas,and 111 pairs of experimental samples meeting the CIELAB gray scale color difference requirements(1.0-14.0)were selected.Ten observers,aged between 22 and 27 with normal color vision,were participated in this study,using the gray scale method from psychophysical experiments to conduct color difference evaluations under the four light sources,with repeated experiments for each observer.The results indicated that the overall effect of the D65 light source on 3D objects color difference was minimal.In contrast,D50 and A light sources had a significant impact within the small color difference range,while the TL84 light source influenced both large and small color difference considerably.Among the four color difference formulas,CIEDE2000 demonstrated the best predictive performance for color difference in 3D objects,followed by CMC(1:1),CIE94,and CIELAB. 展开更多
关键词 Color difference formula 3D objects Light source Gray scale Normalized residual sum of squares
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Effects of Second-Order Sum-and Difference-Frequency Wave Forces on the Motion Response of a Tension-Leg Platform Considering the Set-down Motion 被引量:3
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作者 WANG Bin TANG Yougang CAI Runbo 《Journal of Ocean University of China》 SCIE CAS CSCD 2018年第2期311-319,共9页
This paper presents a study on the motion response of a tension-leg platform(TLP) under first-and second-order wave forces, including the mean-drift force, difference and sum-frequency forces. The second-order wave fo... This paper presents a study on the motion response of a tension-leg platform(TLP) under first-and second-order wave forces, including the mean-drift force, difference and sum-frequency forces. The second-order wave force is calculated using the full-field quadratic transfer function(QTF). The coupled effect of the horizontal motions, such as surge, sway and yaw motions, and the set-down motion are taken into consideration by the nonlinear restoring matrix. The time-domain analysis with 50-yr random sea state is performed. A comparison of the results of different case studies is made to assess the influence of second-order wave force on the motions of the platform. The analysis shows that the second-order wave force has a major impact on motions of the TLP. The second-order difference-frequency wave force has an obvious influence on the low-frequency motions of surge and sway, and also will induce a large set-down motion which is an important part of heave motion. Besides, the second-order sum-frequency force will induce a set of high-frequency motions of roll and pitch. However, little influence of second-order wave force is found on the yaw motion. 展开更多
关键词 tension-leg platform random WAVE SECOND-ORDER WAVE force quadratic transfer function sum-frequency differencefrequency set-down MOTION
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On the Limiting Behavior of Weighted Partial Sums for B Valued Martingale Difference Sequences
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作者 Gan Shi-xin 1, Qiu De-hua 2 1.School of Mathematics and Statistics, Wuhan University, Wuhan 430072, Hubei, China 2. Department of Mathematics, Hengyang Teacher’s College, Hengyang 421008, Hunan, China 《Wuhan University Journal of Natural Sciences》 CAS 2002年第2期133-136,共4页
Let {Xn, n≥1} be a martingale difference sequence and {a nk , 1?k?n,n?1} an array of constant real numbers. The limiting behavior of weighted partial sums ∑ k=1 n a nk X k is investigated and some new results are ob... Let {Xn, n≥1} be a martingale difference sequence and {a nk , 1?k?n,n?1} an array of constant real numbers. The limiting behavior of weighted partial sums ∑ k=1 n a nk X k is investigated and some new results are obtained. 展开更多
关键词 p-smoothable Banach space weighted partial sum martingale difference sequence strong law of large numbers
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Effects on Sum and Difference Patterns by Adaptive Null
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作者 Xie Lianggui and Jiang Xinfa(Beijing Institute of Radio Measurement, P. O. Box 3923, Beijing 100854, China) 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 1994年第1期15-23,共9页
This paper presents a simple method of forming sum and difference patterns with adaptivenulls. The effects on the sidelobe level and the pointing null of difference pattern by adaptive null areanalyzed. The result tha... This paper presents a simple method of forming sum and difference patterns with adaptivenulls. The effects on the sidelobe level and the pointing null of difference pattern by adaptive null areanalyzed. The result that the increment value of the envelope of the sidelobe level under the effect ofa null is less than l.6dB is proved. The formula about shift value of the pointing null which is thefunction of the jammer direction and array parameters is given in the paper. 展开更多
关键词 Adaptive null sum and difference patterns Shift value of the pointing null.
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Sensibility to Changes of Vibrational Modes of Excited Electron: Sum Frequency Signals Versus Difference Frequency Signals
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作者 GU An-Na LIANG Xian-Ting 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第3期506-512,共7页
In this paper, we investigate a two electronic level system with vibrational modes coupled to a Brownian oscillator bath. The difference frequency generation (DFG) signals and sum frequency generation (SFG) signal... In this paper, we investigate a two electronic level system with vibrational modes coupled to a Brownian oscillator bath. The difference frequency generation (DFG) signals and sum frequency generation (SFG) signals are calculated. It is shown that, for the same model, the SFG signals are more sensitive than the DFG signals to the changes of the vibrational modes of the electronic two-level system. Because the SFG conversion efficiency can be improved by using the time-delay method, the findings in this paper predict that the SFG spectrum may probe the changes of the microstructure more effectively. 展开更多
关键词 difference frequency signals sum frequency signals response functions SUSCEPTIBILITY
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Fractional sum and fractional difference on non-uniform lattices and analogue of Euler and Cauchy Beta formulas
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作者 CHENG Jin-fa 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2021年第3期420-442,共23页
As is well known,the definitions of fractional sum and fractional difference of f(z)on non-uniform lattices x(z)=c1z^(2)+c2z+c3 or x(z)=c1q^(z)+c2q^(-z)+c3 are more difficult and complicated.In this article,for the fi... As is well known,the definitions of fractional sum and fractional difference of f(z)on non-uniform lattices x(z)=c1z^(2)+c2z+c3 or x(z)=c1q^(z)+c2q^(-z)+c3 are more difficult and complicated.In this article,for the first time we propose the definitions of the fractional sum and fractional difference on non-uniform lattices by two different ways.The analogue of Euler’s Beta formula,Cauchy’Beta formula on non-uniform lattices are established,and some fundamental theorems of fractional calculas,the solution of the generalized Abel equation on non-uniform lattices are obtained etc. 展开更多
关键词 difference equation of hypergeometric type non-uniform lattice fractional sum fractional difference special functions Euler’s Beta formula Cauchy’Beta formula
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Research of Tile Type Transceiver Module Integrating with Two-Dimensional Sum Difference Network
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作者 Taifu Zhou Jian Zhang 《Journal of Computer and Communications》 2021年第12期116-124,共9页
<div style="text-align:justify;"> Transceiver module and two-dimensional sum difference network are important components of phased array antenna. In this paper, multilayer printed board is used to inte... <div style="text-align:justify;"> Transceiver module and two-dimensional sum difference network are important components of phased array antenna. In this paper, multilayer printed board is used to integrate millimeter wave multi-channel transceiver circuit and sum difference network. The interconnection between them is realized through RF coaxial vertical transition. At the same time, the heat dissipation design and inter channel shielding design of the module are carried out. The RF and low frequency required by the module are completed through the wiring between and within the dielectric plate layers. Finally, 128 arrays are fabricated and verified by multi-channel passive test. The results show that the type transceiver module integrating with two-dimensional sum difference network has good performance, and 128 channels have excellent amplitude and phase characteristics. The integration technology has the characteristics of lightweight, miniaturization, high integration and low manufacturing cost. It can be widely used in miniaturized phased array antennas. </div> 展开更多
关键词 Multi-Channel Transceiver Two-Dimensional sum difference Network RF Coaxial Vertical Transition High Integration
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Gronwll-Bellman Type Nonlinear Sums-Difference Inequalities and Applications in Difference Equations
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作者 Zizun LI 《Journal of Mathematical Research with Applications》 CSCD 2018年第4期393-410,共18页
In this paper,we establish some general sums-difference inequalities with two variables.The inequalities involve finite sum and every term contains the unknown function of the composite function with the power of pi.I... In this paper,we establish some general sums-difference inequalities with two variables.The inequalities involve finite sum and every term contains the unknown function of the composite function with the power of pi.In the end,we study boundedness of the solution of the difference equations as applications. 展开更多
关键词 sum-difference inequality power MONOTONICITY boundary value problem bound-edness
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Difference beam aided target detection in monopulse radar 被引量:1
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作者 Cai Fei Fan Hongqi +1 位作者 Song Zhiyong Fu Qiang 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2015年第5期1485-1493,共9页
The classical detection step in a monopulse radar system is based on the sum beam only, the performance of which is not optimal when target is not at the beam center. Target detection aided by the difference beam can ... The classical detection step in a monopulse radar system is based on the sum beam only, the performance of which is not optimal when target is not at the beam center. Target detection aided by the difference beam can improve the performance at this case. However, the existing difference beam aided target detectors have the problem of performance deterioration at the beam center, which has limited their application in real systems. To solve this problem, two detectors are proposed in this paper. Assuming the monopulse ratio is known, a generalized likelihood ratio test (GLRT) detector is derived, which can be used when targeting information on target direction is available. A practical dual-stage detector is proposed for the case that the monopulse ratio is unknown. Simulation results show that performances of the proposed detectors are superior to that of the classical detector. 展开更多
关键词 DETECTION difference beam Monopulse radar sum beam Generalized likelihood ratiotest
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基于线模反行波一阶差分的多端柔性直流线路单端方向保护
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作者 邢超 王朋林 +4 位作者 赵四洪 陈仕龙 周前华 欧阳聂庆 毕贵红 《电网技术》 北大核心 2026年第1期401-410,I0178-I0180,共13页
多端柔性直流输电工程中出现T型接线,会使T区左右两侧故障难以区分,需研究多端柔性直流输电线路的保护方案。该文提出一种基于线模反行波一阶差分的多端柔性直流输电线路保护方案,首先,通过分析线路Line1、线路Line2、T区区内故障的线... 多端柔性直流输电工程中出现T型接线,会使T区左右两侧故障难以区分,需研究多端柔性直流输电线路的保护方案。该文提出一种基于线模反行波一阶差分的多端柔性直流输电线路保护方案,首先,通过分析线路Line1、线路Line2、T区区内故障的线模反行波波形传播特征,推导了不同位置故障的线模反行波波形公式,揭示了不同位置故障经过保护装置的线模反行波不同的变化趋势;其次,采用一阶差分来表征线模反行波的变化特征,使用规定时间内两个保护装置的线模反行波一阶差分和的正负来判断T区左侧故障、T区右侧故障和T区区内故障,使用一阶差分绝对值和来判别线路Line1整流侧区内外故障和线路Line2逆变侧区内外故障,使用正负极电压幅值比进行选极。最后,通过仿真表明,方案可以使用线模反行波的一阶差分和作为方向判据来故障区域,可以使用线模反行波的一阶差分绝对值和判别区内外故障。 展开更多
关键词 多端柔性直流输电 线模反行波 波形特征 一阶差分和 线路保护
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自然数等幂和sum (k^m) from k=1 to n计算的新方法 被引量:1
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作者 刘雁鸣 《湖北民族学院学报(自然科学版)》 CAS 2012年第3期260-262,共3页
自然数等幂和问题一直受到国内学者的普遍关注,应用多项式空间的差分来计算自然数等幂和sum (k^m) from k=1 to n,是解决该问题的一个新思路.
关键词 自然数 等幂和 差分
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EXACT EVALUATIONS OF FINITE TRIGONOMETRIC SUMS BY SAMPLING THEOREMS
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作者 M.H. Annaby R.M. Asharabi 《Acta Mathematica Scientia》 SCIE CSCD 2011年第2期408-418,共11页
We use the sampling representations associated with Sturm-Liouville difference operators to derive generalized integral-valued trigonometric sums. This extends the known results where zeros of Chebyshev polynomials of... We use the sampling representations associated with Sturm-Liouville difference operators to derive generalized integral-valued trigonometric sums. This extends the known results where zeros of Chebyshev polynomials of the first kind are involved to the use of the eigenvalues of difference operators, which leads to new identities. In these identities Bernoulli's numbers play a role similar to that of Euler's in the old ones. Our technique differs from that of Byrne-Smith (1997) and Berndt-Yeap (2002). 展开更多
关键词 Trigonometric sums difference equations sampling theorem
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ON ALMOST SURE CONVERGENCE OF WEIGHTED SUMS OF RANDOM ELEMENT SEQUENCES
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作者 甘师信 《Acta Mathematica Scientia》 SCIE CSCD 2010年第4期1021-1028,共8页
We mainly study the almost sure limiting behavior of weighted sums of the form ∑ni=1 aiXi/bn , where {Xn, n ≥ 1} is an arbitrary Banach space valued random element sequence or Banach space valued martingale differen... We mainly study the almost sure limiting behavior of weighted sums of the form ∑ni=1 aiXi/bn , where {Xn, n ≥ 1} is an arbitrary Banach space valued random element sequence or Banach space valued martingale difference sequence and {an, n ≥ 1} and {bn,n ≥ 1} are two sequences of positive constants. Some new strong laws of large numbers for such weighted sums are proved under mild conditions. 展开更多
关键词 Strong law of large number almost sure convergence Lp convergence weighted sums Banach space valued random element sequence Banach space martingale difference sequence
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联立角度估计的GEO卫星地面站和差波束干扰消除方法 被引量:1
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作者 安建 姬涛 王磊 《电讯技术》 北大核心 2025年第1期63-67,共5页
随着地面用频设备的不断增多,卫星通信受到的电磁干扰日益严重,从波束旁瓣进入的大电平干扰信号会造成极大的危害,导致接收信号信干噪比降低,信息无法解调。针对该问题提出了一种联立角度估计的和差波束干扰消除方法,一方面通过和波束... 随着地面用频设备的不断增多,卫星通信受到的电磁干扰日益严重,从波束旁瓣进入的大电平干扰信号会造成极大的危害,导致接收信号信干噪比降低,信息无法解调。针对该问题提出了一种联立角度估计的和差波束干扰消除方法,一方面通过和波束及差波束估计出干扰信号的来波方向,另一方面基于估计结果利用和差波束的接收信号加权求和消除从旁瓣进入系统的干扰信号。仿真实验证明,所提方法能够有效抑制地球静止轨道(Geostationary Orbit,GEO)卫星地面站的旁瓣干扰,在低信噪比和强干扰条件下能够保持良好的性能,干扰抑制效果达到50 dB以上。 展开更多
关键词 卫星地面站 卫星信号 旁瓣干扰 和差波束 干扰对消 角度估计
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基于智能多分类和迁移学习的和差波束弹载雷达运动目标检测方法
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作者 王赵隆 张小宽 +2 位作者 冯为可 孙华龙 王童 《雷达学报(中英文)》 北大核心 2025年第6期1430-1450,共21页
针对现有和差波束弹载雷达运动目标检测方法所需训练距离单元数量较大、实际检测性能较低的问题,该文提出了一种基于智能多分类和网络参数迁移学习的运动目标检测新方法,其基本思路为利用少量训练距离单元数据构建数据集对深度卷积神经... 针对现有和差波束弹载雷达运动目标检测方法所需训练距离单元数量较大、实际检测性能较低的问题,该文提出了一种基于智能多分类和网络参数迁移学习的运动目标检测新方法,其基本思路为利用少量训练距离单元数据构建数据集对深度卷积神经网络进行训练,将待测距离单元数据分类为杂波类(即无目标类)和对应不同多普勒频率的目标类。考虑到利用实测数据进行在线训练所需的计算资源较多、时间较长,该文首先构建了和差波束弹载雷达运动目标检测的回波信号模型,并基于实测数据进行验证,用于产生仿真数据进行网络离线训练。针对现有典型卷积神经网络参数较多、复杂度较高、训练效率较低等问题,该文基于特征融合模块(FFM)和空间注意力模块(SAM)对DenseNet网络进行改进,构建了FFM-SAM-DenseNet智能多分类器。由于基于智能多分类的检测方法在对不同待测距离单元数据进行处理时需重新训练网络,其整体收敛时间较长、速度较低。为解决该问题,该文引入迁移学习策略,将不同待测距离单元所对应多分类器的网络参数进行共享,以加快所提方法的整体收敛速度。仿真和实测数据处理结果表明,该文所提方法可以基于少量训练距离单元数据,获得相比现有方法更优的运动目标检测性能。 展开更多
关键词 弹载雷达 和差波束 运动目标检测 卷积神经网络 迁移学习
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基于分布式共形阵列天线的和、差波束综合方法研究
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作者 李发政 孙兆阳 +3 位作者 纪永刚 周航 李凉海 王筝 《现代电子技术》 北大核心 2025年第7期11-15,共5页
分布式共形阵列天线可充分利用载体外形有效孔径面积,依托其实现和、差波束,在无人机载雷达导航、目标跟踪等方面具有较高的应用价值。首先,将利用电磁全波分析得到的局部坐标系下的单元方向图旋转变换到全局坐标系下,基于该单元方向图... 分布式共形阵列天线可充分利用载体外形有效孔径面积,依托其实现和、差波束,在无人机载雷达导航、目标跟踪等方面具有较高的应用价值。首先,将利用电磁全波分析得到的局部坐标系下的单元方向图旋转变换到全局坐标系下,基于该单元方向图进行矢量叠加得到阵列的远区总场。进一步地,以每个阵元的激励信号权重作为优化变量,利用遗传算法对幅值加权优化实现和、差波束低副瓣综合。通过构建4×4×4的多平面组合分布式共形阵列天线进行实验仿真验证,遗传算法对提高该类阵列天线的和、差波束低副瓣性能是有效的;同时,利用电磁全波分析证明天线单元方向图进行阵列总场叠加是可行的,使天线单元的选型更加多样化,可以更好地满足无人机载雷达应用需求。 展开更多
关键词 分布式共形阵列天线 遗传算法 和、差波束 电磁全波分析 方向图计算 矢量叠加
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