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为了克服正交小波变换用于图像复原引起的振铃现象,提出了一种基于小波域双层贝叶斯模型的图像复原算法.采用移不变小波变换,经过简单的转换,使计算复杂度较正交小波变换法并没有显著增加.对于涉及小波系数和超参数的估计问题,通过双层贝叶斯模型方法解决.首先使用局部高斯分布作为第一层模型,主要用于刻画原始图像小波系数的先验分布;第二层模型用于对超参数的估计,假设局部逆方差为服从Gamma分布的随机变量.基于双层贝叶斯模型,采用最大后验概率估计(MAP)同时进行参数估计与图像复原,计算机实验验证了该方法的有效性. 相似文献
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用于FFT频谱分析和数字正交解调中的正交信号处理技术,一般都需要快速地计算一对正交信号的幅度.目前广泛采用的是基于A=aX+bY模型的一线近似算法,该算法的优点是计算简单,速度快,但是会有10%左右的误差.由此提出了一种三线近似算法,在计算复杂度没有明显提高的情况下,计算误差小于1%. 相似文献
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多分辨信号和图像模型可用于捕获图像中平滑和奇异区域的统计结构,但是,基于正交小波变换的模型受到平移变化的影响从而降低了其准确性和实时性.本文将邻域隐马尔科夫模型LCHMM( Local Contextual Hidden Markov Model)扩展到复小波的范围,提出了一种基于复小波的邻域隐马尔科夫模型C-LCHMM( Local Contextual Hidden Markov Model Based On Complex Wavelet),该模型具有近似平移不变性及分辨率高的特点、能够捕获小波系数的邻域的统计特征、且计算复杂度小.仿真试验表明基于复小波邻域隐马尔科夫模型(C-LCHMM)用于图像去噪的效果优于典型的去噪算法. 相似文献
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针对热敏电阻温度传感器应用中存在的非线性问题,提出应用递推最小二乘法训练正交基(OBF)神经网络进行非线性补偿的方法.研究结果表明,与RBF神经网络非线性补偿模型和BF神经网络非线性补偿模型相比,该正交基神经网络非线性补偿模型具有误差小,精度高,训练次数少的优点,故为一种有效的非线性补偿方法,在测控领域具有实用价值. 相似文献
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该文基于正交序列集,研究了一类新的零相关区(ZCZ)非周期互补序列(ZACS)集构造方法,所得到的序列集参数达到最优,且在满足Z|N的条件下零相关区长度可以灵活选择.该方法所构造的序列具有理想的自相关性能和组内互补特性.通过调整参数q,可得到多个不同的序列集.同时,基于多电平完备序列,给出了一类高斯整数正交序列集的构造方法,得到的高斯整数正交序列集可以用于非周期互补序列集的构造.所提方法构造的零相关区非周期互补序列集用于多载波码分多址系统中可以降低多径干扰、多址干扰,也可以作为训练序列用于多输入多输出信道估计中. 相似文献
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《Microwave Theory and Techniques》1987,35(4):396-402
A nonlinear circuit model of the GaAs MESFET is developed by extracting circuit parameters from dc and small-signal RF measurements in a systematic manner. The circuit model is then analyzed by an efficient algorithm called the modified multiple-reflection method. For the first time, this method is applied to MESFET circuit analysis. Compared with the original multiple-reflection method, the modified multiple-reflection method shows a dramatic increase in convergence speed. The validity of the nonlinear MESFET model is confirmed by comparing the simulation results with experimental data. 相似文献
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This paper discusses the possibilities of using the circuit simulation program, simulation program with integrated circuit emphasis (SPICE) for the simulation of partial element equivalent circuit (PEEC) models. After an introduction into the PEEC method, the simulation of quasi-stationary models is considered. An enhancement of SPICE is described, allowing the simulation of retarded PEEC models. This enables the computation of electric fields radiated from an interconnection structure. With the modified SPICE simulator it is possible to use existing SPICE models and combine them with full wave PEEC models 相似文献
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分析了介质谐振振荡器的起振和稳频的原理,研究了一种低相位噪声的介质谐振振荡器的设计方法。以X波段为例,利用CST Microwave Studio 2010软件仿真了微带线与介质谐振器耦合的模型,将仿真得到的结果导入S2P文件中。再利用Agilent ADS 2011软件仿真介质谐振振荡器的完整电路,采用S参数仿真和谐波仿真分析等方法设计介质谐振振荡器,结合理论分析,调整和修改实验电路的参数值,使模型达到最好的优化结果。最后通过测试验证仿真结果。采用NEC公司的2SC5508芯片作为放大器,得出微波振荡器的输出频率为10.6 GHz,输出功率为5.19 dBm和较低的相位噪声,其在偏离中心频率10 kHz处小于-121 dBc/Hz。 相似文献
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Elzinga M. Virga K.L. Zhao L. Prince J.L. 《Advanced Packaging, IEEE Transactions on》2000,23(2):142-147
As digital circuits approach the GHz range, and as the need for high performance wireless devices increases, new simulation tools which accurately characterize high frequency interconnects are needed. In this paper, a new macromodeling algorithm for time domain simulation of interconnects is presented. The algorithm incorporates Householder LS curve-fitting techniques. The approach generates a universal macromodeling tool that enables simulation of interconnects in a modified version of simulation program with integrated circuit emphasis (SPICE). This results in a method that conveniently incorporates accurate EM models of interconnects or experimental data into a circuit simulator. The time domain simulation results using this new tool are compared with results from other simulators 相似文献
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提出了一个多输出电流差分跨导放大器(MO-CCCDTA),利用它设计了一个电流模式二阶带通、二阶高通带阻和二阶低通带阻电路,以此为基础,利用级联法设计了电流模式六阶椭圆带通滤波器.该滤波器仅使用3个MO-CCCDTA、1个CDTA和7个电容,通过调节偏置电流,各滤波器参数均能被电控调谐.计算机仿真表明电路正确有效. 相似文献
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Shi Zhiguo Ran Lixin Chen Kangsheng 《电子科学学刊(英文版)》2006,23(3):433-436
Chaotic Colpitts circuits with fundamental frequency f^* beyond 1GHz are studied by both circuit simulation and experiment using Philips' broadband transistor with threshold frequency of 25GHz. For the basic configuration of Colpitts circuit with f^* of about 1,6GHz, broadband continuous power spectra could be obtained from both circuit simulations and experiments. The harmonics of the observed signal from Agilent PSA/ESA spectrum analyzer are as noticeable as far as 12GHz. A modified Colpitts circuit structure employing the parasitic inductance of BJT (Bipolar Junction Transistor) is also proposed and investigated. By circuit simulation, chaotic attractor and broadband continuous power spectra could be obtained from the modified Colpitts circuit with f^* of about 3.5GHz. Because the parasitic effects of the prototype board, the experiment result of the modified Colpitts circuit does not agree well with the simulation result. The gap between the simulation and experimental result could be bridged by replacing the lumped circuit elements with distributed ones. 相似文献
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This paper presents a modified design method for linear transconductor circuit in 130 nm CMOS technology to improve linearity,
robustness against process induced threshold voltage variability and reduce harmonic distortion. Source follower in the adaptively
biased differential pair (ABDP) linear transconductor circuit is replaced with flipped voltage follower to improve the efficiency
of the tail current source, which is connected to a conventional differential pair. The simulation results show the performance
of the modified circuit also has better speed, noise performance and common mode rejection ratio compared to the ABDP circuit. 相似文献
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B. Chakraborty 《International Journal of Electronics》2013,100(7):671-682
This paper describes a phase locked loop employing a low voltage VCO using modified ECL inverter cells. The VCO circuit employed, features a positive feed back scheme to improve the operating frequency. The phase detector used in the PLL also uses a positive feedback scheme to improve the locked range and to reduce supply voltage of operation of the entire circuit. An improvement of locked range of around 35% was obtained from circuit simulation (using PSPICE) as well as from practical circuit, using discrete components. The minimum supply voltage required here is 2.5 volts. Some biomedical applications of this PLL are also proposed. 相似文献