共查询到20条相似文献,搜索用时 15 毫秒
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The uniformity of the (BF3 + 2% Ar) plasma is investigated by the two-view emission’s optical tomography in an experimental plasma-chemical reactor. This made it possible to reconstruct the lateral concentration distribution of both the ion plasma component B+ and free radicals F*. To investigate the possibilities of a tomographic algorithm, the experiment was performed at various pressures in the reactor chamber, an asymmetric gas input was used, artificial nonuniformities of the near-wall magnetic field were introduced, and the influence of the silicon wafer on the lateral particle’s distribution was investigated. 相似文献
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针对图像的模糊算法优化问题,首先选取高斯分布拟合自然图像的分布特性,利用双边滤波器从模糊图像中提取出清晰的图像边缘。针对降噪进行参数设置,在初步估计出模糊核之后,对模糊核进行正规化修正工作。最后在图像复原阶段,利用优化的凸函数拟合自然图像分布,并利用快速傅里叶变换提高算法计算速度。实验结果,表明该模糊核优化算法与现有的其他算法相比,复原后的图像具有更好的视觉效果,且计算时间减少约20%。 相似文献
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针对单部雷达提取目标微动参数精度不高和难以实现三维重构的问题,提出了一种基于多视角微动信息自适应融合的三维重构新方法。首先,建立了组网雷达模型和锥体进动模型,在详细分析各散射点微距离变化关系的基础上,对不同视角下的锥顶散射点进行了匹配关联。然后,以每两部雷达的观测信息作为一个目标参数求解组合,采用基于估计方差最小的加权融合算法对各组合求得的参数进行优化处理。最后,利用优化后的参数求解出目标锥顶坐标和锥旋矢量,实现了锥体目标的三维重构。仿真结果表明该方法能有效实现高精度参数的提取和锥体目标的重构。 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》1969,15(6):706-709
By studying the algebraic structure of the parity check matrix of a linear code we show that the weight distribution is a function only of the quantitiesN_{upsilon}^{u} , the number ofupsilon columns of the parity check matrix with ranku . We apply this to obtain a new formula for the weight distribution of the distance3 s -ary Hamming code and for the distance4 s -ary conic code. We give the definition of a conic code and some of its properties. 相似文献
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《Electron Devices, IEEE Transactions on》1980,27(8):1455-1459
The extension of the general process simulator SAMPLE to plasma etching and metallization is described. The etching algorithm is divided into isotropic, anisotropic, and direct milling components and is suitable for modeling wet etching, plasma etching, reactive ion etching, and ion milling. Separate deposition algorithms are used for CVD, sputtering, and planetary deposition. With the extension, it is possible to use a simple keyword repertoire to simulate a sequence of photolithography, etching, and deposition steps to obtain device cross sections at each stage of fabrication. 相似文献
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基于Fourier-Mellin变换和相干系数法的重复轨道干涉SAR图像配准新方法 总被引:3,自引:1,他引:2
相对于单轨双天线InSAR系统,重复轨道InSAR系统由于轨道不能完全平行,导致InSAR图像对间存在夹角,使其配准更为困难。该文针对非平行重复轨道的InSAR问题,提出了一种结合Fourier-Mellin变换和相干系数法的InSAR图像配准算法,对存在夹角的SAR复图像对进行精确配准。该方法用于粗配准时,通过引入非线性图像幅度变换预处理,克服了Fourier-Mellin变换无法直接处理SAR图像对幅度分布动态范围大且不均匀的问题,而用于精配准时,通过引入相干系数法,精确估计了复图像对之间存在的微小角度。以SIR-C/X重复轨道的X波段SAR数据为例,详细比较了传统相干系数配准算法和该文算法在配准精度和计算时间上的差异,从而验证了算法的有效性。 相似文献
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圆锥曲线密码学是一种新型的公钥密码学,迄今对圆锥曲线密码学的研究成果都是以有限域GF(p)上的圆锥曲线为基础的.本文将有限域GF(p)上的圆锥曲线C(GF(p))推广为有限域GF(2n)上的圆锥曲线C(GF(2n)),证明了圆锥曲线C(GF(2n))上的点和加法运算构成有限交换群(C(GF(2n)),),并给出了圆锥曲线群(C(GF(2n)),)的阶的计算.此外,提出了使用有限域GF(2n)上的圆锥曲线群构造公钥密码系统,并给出了ElGamal加密方案和数字签名算法(DSA)在圆锥曲线C(GF(2n))上模拟的算法,最后分析其安全性. 相似文献
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Yun Ho Kim Dong Ki Yoon Hyeon Su Jeong Jung Hyun Kim Eun Kyoung Yoon Hee‐Tae Jung 《Advanced functional materials》2009,19(18):3008-3013
A novel fabrication method is developed for the preparation of superhydrophobic surfaces. The procedure uses focal conic structures of semi‐fluorinated smectic liquid crystals (LCs) whose periodic toric focal conic domains (TFCDs) are prepared on a surface modified substrate. Reactive ion etching (RIE) on the periodic TFCD surface leads to a superhydrophobic surface with a water contact angle of ~160° and a sliding angle of ~2° for a 10 µL water droplet. The results show that this phenomenon is due to the development of a dual‐scale surface roughness arising from the nanoscale protuberance caused by applying the RIE process to the top of the microscale TFCD arrays. The unique surface behavior is further verified by demonstrating that RIE on a flat lamellar liquid crystal film, in which the director is aligned parallel with surface, results in a relatively low hydrophobicity as compared to when periodic TFCDs are subjected to REI. The observations made in this publication suggest that a new approach exists for selecting potential candidates of superhydrophic surface formation based on spontaneous self‐assembly in smectic liquid‐crystalline materials. 相似文献
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本文利用流体模型,将无外加恒定磁场的等离子体当作各项同性的有耗媒质,求得圆柱腔结构中的微波场分布。耦合电子、离子运动的流体方程,对微波等离子体的初始形成过程进行了数值模拟计算。结果表明,在电离的初始阶段,电子、离子密度分布与场分布同步。同时,存在一关键电子密度。超过此密度后,微波场在表面快速衰减,气体电离主要在表面进行。 相似文献
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一种双频喇叭馈源的相位中心分析 总被引:1,自引:0,他引:1
多模圆锥喇叭天线是一种应用较广的高效率喇叭天线,它被广泛应用于反射面初级馈源。双频多模圆锥喇叭天线在收发两个频率处的相位中心是不重合的,当其作为反射面馈源时,其相位中心及安放位置的确定对于反射面天线的性能有着不可忽视的影响。从天线相位中心的定义出发,计算了双频多模喇叭天线在收发频率处的相位中心,并对该天线在偏置反射面系统中的安放位置进行了分析,确定了馈源的最佳安放位置。 相似文献
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Zhu Dajun Liu Shenggang 《电子科学学刊(英文版)》1997,14(2):180-185
From the fluid model, the plasma is an isotropic medium. First, it is obtained that the microwave field in a cylindrical cavity filled with plasma, where the microwave comes from vacuum cylindrical waveguide. Coupling with fluid equations for the electron and ion motion, the microwave discharge courses are calculated , The results show that the curves of ion and electron density distributions are similar as the curves of electric field intensity distribution. Abo, a critical electron density is exist. Above this density, microwave field will damp rapidly, this makes the gas ionization mainly happening on the surface. 相似文献
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The radiation from electromagnetic sources in an unbounded, isotropic plasma is treated. Using a two-fluid magnetohydrodynamic approach, the problem is formulated in terms of three orthogonal modes, namely, i) the electromagnetic mode, ii) the electron plasma mode and iii) the ion plasma mode. When formulated in this manner, the radiation from simple electromagnetic sources are obtained easily. Three specific sources are treated, namely, i) a point source of electric current, ii) a uniformly moving charge and iii) a short filament with prescribed current distribution. For the case of the electric dipole and the current filament, the total power radiated in each of the three modes are obtained. A point charge moving uniformly with the velocity of sound, for example, is found to excite only the ion plasma mode. The frequency and the angular spectrum of the emitted radiation are obtained. It is found that at frequencies less than a critical frequency which is approximately equal tosqrt{2} times the ion plasma frequency, the radiation has the character of a simple sound wave. 相似文献
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准确的等离子体参数信息对射频离子源的研制十分重要,为获得这些关键参数,需要借助朗缪尔探针作为研究手段。研究利用COMSOL软件作为研究平台,建立射频离子源的几何模型,并加入探针作为变量,通过仿真模拟得到不同功率下的电子密度、电子温度分布,通过对比有、无探针加入的情况下所得参数的变化趋势,来分析朗缪尔探针对射频离子源的扰动情况。研究结果表明,探针放入等离子体后,会对等离子体产生扰动,等离子体放电中心向右偏移大于1 cm。该研究结果为射频离子源的设计以及朗缪尔探针的测量分析提供了参考。 相似文献
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A. V. Fadeev K. V. Rudenko V. F. Lukichev A. A. Orlikovskii 《Russian Microelectronics》2011,40(2):108-118
In this article, an algorithm of two-aspect emission optical tomography of plasma taking into account apriori data about the
object of investigation is developed. The reconstruction algorithm was tested for statistically large number of phantoms.
The cases of incorrect operation of the suggested algorithm were revealed and the methods of its improvement were suggested.
The improved algorithm of emission optical tomography compatible with industrial plasmochemical reactors of low-temperature
plasma allows us to reconstruct a two-dimensional distribution of plasma particles with the reconstruction error lower than
15% for 90% of randomly selected phantoms. 相似文献
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提出了一种基于时频分布迭代的跳频信号参数估计新算法,利用时频平面最大值,通过计算跳频信号与最优原子时频分布的残差逐次迭代获取匹配于跳频信号分量的时频参数,进而实现跳频信号参数估计.理论分析和仿真结果表明,与基于匹配追踪和粒子群优化的跳频信号参数估计相比,基于时频分布迭代的参数估计算法在保证算法精度的情况下,有效地降低了算法的计算复杂度,为跳频信号盲接收的实时实现提供了一种新方法. 相似文献
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