The analysis of coupled interconnect with process parameter variation based wavelet collocation method

In this paper, a novel approach based on fast wavelet collocation method (FWCM) is presented to solve partial differential equations (PDEs) in coupled on-chip interconnects with parameter variations. After processing PDEs by decomposing variables with wavelet functions, we transfer the PDEs into ordinary differential equations (ODEs), and then use Taylor expansion in the ODEs to approximate the partial complex expression containing inverse matrix. Consequently, we can solve the PDEs with random variables more feasibly. Moreover, this approach provides a new idea for solving other kinds of PDEs with random variables in very large scaled integrated circuits (VLSI). Comparison with HSPICE simulation results shows the method proposed in this paper is effective and accurate.     

UHF RFID tag-antenna matching optimization using VHDL-AMS behavioral modeling

In order to generate a first-time right design, system level modeling and simulation is a major step. Thus, optimization of integrated wireless systems requires the development of behavioral models of the RF link (antenna-medium-antenna) compatible with the microelectronic design tools. Firstly, this paper shows the need of such models within the Top-Down design flow of an UHF RFID system. Then, a behavioral model of a narrow band far field RF link is presented and validated. This model is associated with a new behavioral model of an RFID tag and finally, several examples of tag-antenna matching optimization simulations are presented in order to demonstrate the interest of our approach.     

Fast and accurate DAC modeling techniques based on wavelet theory

Two new modeling techniques based on principles of wavelet theory are described in this article. Macro-model and mathematical model are developed for analog and digital circuit simulation, respectively, for fast and accurate results using exponential function, damped sine wave, and linear waveform. An 8 bit DAC has been implemented to simulate and evaluate the models. The INLs of the macro and mathematical model based simulations are ±0.2LSB, which are the same as HSPICE simulation. The DNLs of HSPICE simulation, macro model, and mathematical model based simulations are ±0.22LSB, ±0.28LSB, and ±0.25LSB, respectively. The simulation times are 2.9 s for macro model, 0.15 s for mathematical model, and 68.09 s for HSPICE simulation.     

一种新的小波图像去噪方法

小波图像去噪已经成为目前图像去噪的主要方法之一,目前的研究主要集中于如何选取阈值使去噪达到较好的效果。边缘信息是图像最为有用的高频信息,在图像去噪的同时,应尽量保留图像的边缘信息,基于这一思想,提出一种新的小波图像去噪方法。用数学形态学算子对图像小波变换后的小波系数进行处理,以去除具有较小支持域的噪声,保留具有连续支持域的边缘。实验结果表明,与普通的小波阈值去噪方法相比,该方法不但可以保留图像的边缘信息,而且能提高去噪后图像的峰值信噪比2～5dB,提高信噪比6～10dB。     

基于几何规划的模拟器件建模与电路性能优化

基于分段线性函数,提出一种新的对模拟器件进行建模的方法,并提出乐观、悲观两种数据拟合算法,两种算法均能较好地拟合MOS管参数。模型建立之后,利用几何规划对电路性能进行优化。乐观算法会得到较好的电路性能,但可能不满足约束条件;悲观算法能够严格满足约束条件,但是得到的电路性能未必最优。在此基础上,提出一种基于响应曲面方法的折衷优化算法,能够得到综合考虑电路性能和约束条件的电路设计参数。最后,以两级放大器为优化实例,证明该方法的有效性。     

Analog wavelet transform using multiple-loop feedback switched-current filters and simulated annealing algorithms

A new approach for implementing continuous wavelet transform (CWT) based on multiple-loop feedback (MLF) switched-current (SI) filters and simulated annealing algorithms (SAA) is presented. First, the approximation function of wavelet bases is performed by employing SAA. This approach allows for the circuit implementation of any other wavelets. Then the wavelet filter whose impulse response is the wavelet approximation function is designed using MLF architectures, which is constructed with SI differentiators and multi-output cascade current source circuits. Finally, the CWT is implemented by controlling the clock frequency of wavelet filter banks. Simulation results of the proposed circuits and the filter banks show the advantages of such new designs.     

Spatial adaptive Bayesian wavelet threshold exploiting scale and space consistency

Threshold selection is critical in image denoising via wavelet shrinkage. Many powerful approaches have been investigated, but few of them are adaptive to the changing statistics of each subband and meanwhile keep efficiency of the algorithm. In this work, an inter-scale adaptive, data-driven threshold for image denoising via wavelet soft-thresholding is proposed. To get the optimal threshold, a Bayesian estimator is applied to the wavelet coefficients. The threshold is based on the accurate modeling of the distribution of wavelet coefficients using generalized Gaussian distribution (GGD), and the near exponential prior of the wavelet coefficients across scales. The new approach outperforms BayesShrink because it captures the statistical inter-scale property of wavelet coefficients, and is more adaptive to the data of each subband. The simplicity of the proposed threshold makes it easy to achieve the spatial adaptivity, which will further improves the wavelet denoising performance. Simulation results show that higher peak-signal-to-noise ratio can be obtained than other thresholding methods for image denoising.     

On the use of behavioral modeling within the RFIC design flow: Satellite receiver case study

In order to generate a first-time right design, system level modeling and simulation is a major step. Thus, performance evaluation of integrated wireless systems requires the development of RF behavioral models compatible with the microelectronic design tools. Firstly, this paper shows the need of such models within the RFIC Top–Down design flow. Then, behavioral modeling techniques are presented and several classical RF block models are described. Those models are used within an RFIC satellite receiver validation example and finally, several performance evaluation examples allow demonstrating the capabilities of behavioral modeling, compared to other very used modeling techniques as mathematical and baseband approaches.     

基于小波变换的加权图像融合方法

提出了一种基于小波变换的多光谱图像与高空间分辨率图像融合方法。该方法通过局部方差准则利用加权平均将高空间分辨率图像和多光谱图像经小波分解的低频分量进行融合,然后将融合的低频分量和高空间分辨率图像的细节分量结合进行小波反演变换得到融合图像。通过和WT方法的融合结果进行对比评价,表明了该方法在提高多光谱图像的空间细节表现能力和保持光谱信息上都有很好的效果。     

新颖的基于小波变换的数字水印方案

随着计算机网络技术与多媒体技术的快速发展,数字产品的版权保护已经成为信息技术领域中最重要的问题之一,提出了一种新颖的基于离散小波变换的数字水印方案,该方案利用改进的Pacthwork算法,将水印嵌入到LL子带中,水印信号在解码过程中无需使用原始图像可快速地重嵌入,该算法利用BCH码来降低误码率,应用所提出的算法,把一个32个字符的水印嵌入到图像中,实现结果表明水印是不可察觉的,经过JPEG有损压缩,低通与中值滤波等图像处理操作后仍是鲁棒的。     

Numerical solutions for orthogonal wavelet filters by Newton method

The wavelet transform has recently generated much interest in applied mathematics, signal processing and image coding. Mallat (1989) used the concept of the function space as a bridge to link the wavelet transform and multiresolution analysis. Daubechies (1990) added regularity conditions to find 2N, 2N10, tap coefficients for orthogonal wavelet filters. Owing to the difficulty of finding their closed solutions for large N a numerical method called the Newton method is proposed. We constructed the orthogonal wavelet filter with 2N-tap coefficients by N linear equations and N nonlinear equations. The 2N-tap, 2N10, coefficients we found are very consistent with those of Daubechies. Also, the method can be used to find the orthogonal wavelet filter with N-tap coefficients for N>10.     

基于小波分析与类内最小方差法的车道线检测

在车道偏离预警、防止及车道保持等基于机器视觉的驾驶安全辅助系统中。在道路图片中,为了能提取出完整的直车道线,本文提出了一种基于小波分析与计算梯度方向角类内最小方差法相结合的算法。该算法首先利用小波分析计算出边缘像素点的梯度幅值和梯度方向角,得到道路图像的边缘;然后将二值化处理过的图像用8领域面积去噪法去除噪声区域,并进行连通域的标记;在提取直车道线时,利用类内最小方差法计算各个连通域边界上点的梯度方向角最小方差,最后设定阈值分离出直线车道线,达到车道线检测的目的。实验仿真结果表明,本算法能够很好的检测出直线车道线,相比于目前其他文献的方法有较高的检全率。将有助于智能驾驶辅助系统研究技术的发展。     

基于Verilog-A的模拟电路行为模型及仿真

分析了模拟硬件描述语言Verilog—A的特点及模型结构,根据仿真速度和仿真精度的折衷考虑,设计实现了模拟开关、带隙基准电压源及运放的Verilog—A行为模型。根据数模转换器(13AC)的特性,基于Verilog—A设计了DAC参数测试模型,也建立8位DAC的行为模型。所有行为模型都在Cadence Spectre仿真器中实现了仿真验证。     

用统一建模语言进行教案设计建模的应用研究

针对传统教案设计过程中的弊端,提出了一种以统一建模语言(UML)为基础的教案设计建模方法,并结合"计算机操作系统"这门课程的教学实践,探讨了这种教案建模方法在教学实际中的具体应用与实施过程.这种方法将UML建模方法引入到教案设计中,按照自顶向下、逐步细化的方式分别建立起教案的课题模型,静态模型和动态模型,在教学实践中取得了较好的应用效果.     

小波包域值法去除合成孔径雷达图像斑点噪声

合成孔径雷达(SAR)图像的斑点噪声使图像的解译能力明显降低,影响了SAR图像的应用,去除图像斑点噪声是SAR图像处理及应用的前提。去除的方法在图像域有很多,在频率域,也有基于FFT变换和小波变换的许多方法。文中根据沙漠地区的SAR图像的特点,对基于图像域和频率域的几种滤波方法进行了比较,提出了一种基于小波包变换的SAR图像斑点噪声去除方法,结果表明该方法既去除了斑点噪声,又保持了边缘特征信息。     

遗传小波神经网络的非线性模拟电路故障诊断方法

提出了一种将遗传算法(GA)、神经网络与小波变换相结合对非线性模拟电路进行故障诊断的方法;分析了传统BP型神经网络在非线性模拟电路故障诊断中存在的缺陷;提出了一种新的解决方法--利用小波变换对非线性电路故障信号进行预处理,对故障信号中的冗余信息进行剔除,然后利用遗传算法优化BP网络参数,如网络权值、阈值等.利用该方法对非线性电路进行故障诊断,有利于提高神经网络对电路故障诊断的智能性及识别故障类别的能力,提高故障诊断的精度与速度.实验结果表明,该方法是可行的.     

Behavioral modeling, simulation and synthesis of multi-standard wireless receivers in MATLAB/SIMULINK

This paper presents a SIMULINK block set for the behavioral modeling and high-level simulation of RF receiver front-ends. The toolbox includes a library with the main RF circuit models that are needed to implement wireless receivers, namely: low noise amplifiers, mixers, oscillators, filters and programmable gain amplifiers. There is also a library including other blocks like the antenna, duplexer filter and switches, required to implement reconfigurable architectures. Behavioral models of building blocks include the main ideal functionality as well as the following non-idealities: thermal noise, characterized by the noise figure and the signal-to-noise ratio, and non-linearity, represented by the input-referred second-order and third-order intercept points, IIP₂ and IIP₃, respectively. In addition to these general parameters, some block-specific errors have also been included, like oscillator phase noise and mixer offset. These models have been incorporated into the SIMULINK environment making an extensive use of C-coded S-functions and reducing the number of library block elements. This approach reduces the simulation time while keeping high accuracy, which makes the proposed toolbox very appropriate to be combined with an optimizer for the automated high-level synthesis of radio receivers. As an application of the capabilities of the presented toolbox, a multi-standard direct-conversion receiver intended for 4G telecom systems is modeled and simulated considering the building block requirements for the different standards.     

基于元模型的视图层PIM建模方法

模型驱动架构的核心思想是将建模语言当作开发语言使用,基于UML的平台无关模型建模方法主要关注于系统的体系结构与业务逻辑设计,对视图层支持较差。研究基于元模型的视图层PIM建模方法,给出视图层PIM模型中界面逻辑模型和界面布局模型的表示法及语义内容;基于EMOF元模型对UML建模语言进行扩展;使其对上述两种模型提供语义上和表示法的支持,最后基于Eclipse GMF框架开发了视图层PIM辅助设计工具GMTP。     

激光陀螺小波滤波方法研究

为了减小激光陀螺随机误差对激光捷联惯导系统对准、导航精度的影响,采用小波分析方法对其输出信号进行滤波处理.开发了评估软件,并对其在实际系统中滤波前后效果进行了深入研究.结果表明,评估软件准确可靠,小波分析方法简单实用,特别适合激光陀螺信号的处理,在很大程度上提高了系统对准、导航精度.     

无线传感器网络可靠性建模方法

无线传感器网络部署设计的基础就是可靠性,因此,对无线传感器网络可靠性研究已经成为全世界在这个领域中研究的一个重点内容。无线传感器网络可靠性研究的一个有效方法就是建立数学模型。为了能够更好地进行无线传感器网络可靠性的建模,本文先介绍了无线传感器网络结构和节点模型,然后主要对无线传感器网络可靠性建模方法进行分析,提出了K-可靠性模型,并对无线传感器网络系统设计时参考依据进行简单说明。经过实践证明,无线传感器网络的可靠性完全能够通过K-可靠性模型进行测量。