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本文介绍了一种合成孔径雷达(Synthetic Aperture Radar, SAR)目标特征的操控方法,采用非周期相位调制表面(Phase-Switched Screen, PSS)实现对重要目标图像特性的有效压制.依靠PSS反射式防护手段,对雷达回波信号进行快-慢时间域的二维联合非周期相位调制,在SAR接收处理后可形成矩形块状压制区域.通过调控快时间与慢时间码元宽度,可以实现生成矩形区域的面积控制.该方法本质是一种无源防护方法,兼具响应时间快、不易暴露、设备简单等优势.在此基础上,本文提出了压制区域面积、压制区域干信比对特征操控效果进行表征,分析了PSS调制参数对操控效果的影响.最后,SAR实测数据仿真验证了所提方法的有效性. 相似文献
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提出了一种新的轮式移动机器人位置与角度的检测方法。首先在机器人上方做一个黑色矩形标记,标记物的长边与机器人的正向平行,然后在图像平面内,用CAMShift算法对机器人进行跟踪。在跟踪的过程中,可以获得只包含目标体的子图片,即"感兴趣区域"。子图片的中心即为轮式运动机器人的几何中心。采用适当的方法检测出矩形标记物长边与图像坐标X轴之间的夹角,并以此角度作为机器人的方向角度。 相似文献
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为了解决绝缘子目标检测中无法精确定位的问题,该文基于深度学习提出一种绝缘子定向识别算法,通过在轴对齐检测框中加入角度信息,可有效解决常规深度学习算法无法精确定位目标的问题。该算法首先将角度旋转参数引入轴对齐矩形检测框中构成定向检测框,然后将该参数偏移量作为第5参数加入到损失函数中进行迭代回归,同时为提高检测精度在训练过程中使用Adam算法替代随机梯度下降(SGD)算法进行损失函数优化,最终可获得绝缘子定向检测模型。实验分析表明,加入旋转角度的定向检测框可有效对绝缘子目标进行精确定位。 相似文献
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本文选用矩形耦合腔作为太赫兹扩展互作用振荡器(EIO)的慢波结构,鉴于其结构的复杂性,采用等效电路方法计算其色散.详细研究了腔体和耦合槽的电路参数,计算了不同结构尺寸、圆形和矩形电子通道的0.12THz和0.225THz慢波结构的色散特性.并采用专业电磁软件,研究了不同结构参数下的色散特性、耦合阻抗和特征阻抗.通过对色... 相似文献
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A new method for analyzing the influence of extrinsic parameters, such as contact shape and contact area, on the contact resistance of the metal-semiconductor system is developed. The method incorporates a previously established contact theory in the Transmission Line Model used earlier for rectangular and circular contacts. Theory is also extended to the circular ring contact in this article. Good agreement with measured results substantiates the applicability of the method for the design of contact shapes and areas in semiconductor device fabrication processes.Various contact shapes and areas are investigated and the total contact resistances are compared to one another. It is shown that the contact with long thin stripes possesses the lowest contact resistance. 相似文献
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《Microwave Theory and Techniques》1966,14(8):384-391
This paper describes the operating principle and the properties of a resonant cavity type mode transducer which was newly devised. The theoretical equations necessary for designing the mode transducer from a TE/sub 10/ mode of a rectangular waveguide to an arbitrary mode of a circular waveguide have been derived, and a design method using the coupling parameters is discussed. The experiments were made for the rectangular TE/sub 10/-circular TE/sub 01/, mode transformation in the 50 Gc band. Showing an example (N=1), the transfer loss, input SWR and mode purity were 1.34 dB, 1.13, and 95 percent (power contents), respectively, at the resonant frequency of 50 Gc/s. The 3 dB bandwidth of the transfer loss was 83 Mc/s at the constant cavity length, but it can be made much larger if the cavity length is adjusted according to the frequency change. This mode transducer is unique in that various modes can be excited purely in the circular guide by merely varying the cavity length. 相似文献
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Xiannuan Liang Yang Xiao Jingyuan Zhang Hongmei Deng Athanasios V. Vasilakos 《Telecommunication Systems》2013,52(4):2519-2532
In this paper, we are interested in a single robot detecting intrusions across a rectangular perimeter. We build a stochastic model to analyze the detection quality achieved by a single robot moving along the rectangular perimeter, based on the velocity and the mobility pattern. We define the following intrusion event mode: intrusions occur at a random point along the rectangular perimeter, and stay at that point for a random length of time. In our model, a robot is set to periodically move along a certain route at a variable speed. We derive the general expression for intrusion loss probability. Under the reasonable assumption that, once an intrusion takes place at a random point in the rectangular perimeter, it stays there for a random length of time, which follows an exponential distribution, we then derive the solution to the above problem. 相似文献
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针对灰霾天气条件下主要污染物粒子,PM2.5主要组分,以硫酸铵和碳质气溶胶粒子为典型粒子,运用T矩阵方法研究了这两种粒子不同形态的散射特性,包含椭球体(长短轴比a/b=1/2,1/3,2/1),圆柱体(直径与长度比D/L=1/2,1/3,1/1,2/1)及切比雪夫形(多项式n=2,形变参数=-0.1,0.1),两种粒子在不同形态下所对应的散射、消光及吸收效率因子随尺度参数的变化规律。结果表明,硫酸铵非球形粒子在尺度参数小于1时,不同形状粒子效率因子差异很小,从尺度参数大于1开始,散射、消光效率因子随尺度参数先增加后震荡减小,粒子吸收非常弱;而碳质气溶胶粒子在尺度参数小于2时,不同形状粒子效率因子差异很小,尺度参数大于2开始,各效率因子随尺度参数先增加然后缓慢减小,并且对光场具有较强的吸收作用。该研究结果可用于大气灰霾粒子探测分析,发展大气环境污染防护科技。 相似文献
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The design method of mode selective directional couplers from a transverse electric mode in a circular waveguide to the fundamental mode in a rectangular wave guide is presented in this paper. The design results for a TE01 circular mode coupler intended for use in the output power measurement of a high power gyroklystron are reported; these results indicate that more than 50-80dB directivity and sufficient suppression of unwanted modes can be obtained with a coupler less than 07m in length. The effects of frequency and rectangular wave guide size on coupler parameters are also discussed in this paper 相似文献
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为了获得高均匀性、对称性及一些特殊形状强度分布的白光发光二极管(LED)光束以满足某些特定的需求, 基于白光LED光源为朗伯光源的特性, 运用自由曲面透镜的方法对LED光束进行了光束整形, 分别采用单一自由曲面透镜以及全内反射(TIR)透镜与微透镜阵列组合两种不同的整形结构, 进行了加工工艺和原理理论分析, 并通过了实验验证。结果表明, 实验得到的圆形均匀光斑, 其总光线利用率高达96%, 有效面积光线利用率为88.4%;得到的矩形均匀光斑, 总光线利用率为91%, 有效面积光线利用率为78.7%, 光束均匀度均在60%以上; 通过自由曲面透镜方法进行白光LED光束整形效果极佳。该整形方法为白光LED光源的进一步广泛应用提供了重要的指导。 相似文献