非规则矩形电阻在Calibre LVS中阻值提取问题研究与实现

本文首先介绍了Calibre LVS的基本流程。在分析了现有的在LVS过程中电阻版图阻值提取方法的优缺点基础上提出了一种新颖的电阻的提取方法,经过Calibre LVS验证可以有效的减小了电阻阻值提取的误差,为非规则矩形电阻提取提供了一种新的、更加精确的方法     

一种新的求解ULSI双介质互连电容的模拟电荷法

论述了一种模拟电荷法与镜像格林函数法相结合,对模拟电荷用DFP法进行最优设置的提取双介质ULSI互连电容参数的基本算法,并与其它互连电容模拟软件模拟的结果进行了比较,相对偏差小于10%,表明这种新的模拟电荷法是有效的和可行的．     

一种新的求解ULSI双介质互连电容的模拟电荷法

论述了一种模拟电荷法与镜像格林函数法相结合 ,对模拟电荷用 DFP法进行最优设置的提取双介质 UL SI互连电容参数的基本算法 ,并与其它互连电容模拟软件模拟的结果进行了比较 ,相对偏差小于 10 % ,表明这种新的模拟电荷法是有效的和可行的     

Robust algorithm for estimation of time-varying transfer functions

We introduce a new method to estimate reliable time-varying (TV) transfer functions (TFs) and TV impulse response functions. The method is based on TV autoregressive moving average models in which the TV parameters are accurately obtained using the optimal parameter search method which we have previously developed. The new method is more accurate than the recursive least-squares (RLS), and remains robust even in the case of significant noise contamination. Furthermore, the new method is able to track dynamics that change abruptly, which is certainly a deficiency of the RLS. Application of the new method to renal blood pressure and flow revealed that hypertensive rats undergo more complex and TV autoregulation in maintaining stable blood flow than do normotensive rats. This observation has not been previously revealed using time-invariant TF analyses. The newly developed approach may promote the broader use of TV system identification in studies of physiological systems and makes linear and nonlinear TV modeling possible in certain cases previously thought intractable.     

利用物质反常色散实现浓度选择性测量

提出一种有助于提高溶液浓度的选择性测量的新传感方法，讨论了这种方法的理论依据物质反常色散，分析了具有吸收谱的物质复折射率随波长变化的关系，研究了反射率的衰减及衰减全反射现象．实验表明这种传感方法是可行的     

Incorporation of correlated structural images in PET image reconstruction

Reports on a new method in which spatially correlated magnetic resonance (MR) or X-ray computed tomography (CT) images are employed as a source of prior information in the Bayesian reconstruction of positron emission tomography (PET) images. This new method incorporates the correlated structural images as anatomic templates which can be used for extracting information about boundaries that separate regions exhibiting different tissue characteristics. In order to avoid the possible introduction of artifacts caused by discrepancies between functional and anatomic boundaries, the authors propose a new method called the "weighted line site" method, in which a prior structural image is employed in a modified updating scheme for the boundary variable used in the iterative Bayesian reconstruction. This modified scheme is based on the joint probability of structural and functional boundaries. As to the structural information provided by CT or MR images, only those which have high joint probability with the corresponding PET data are used; whereas other boundary information that is not supported by the PET image is suppressed. The new method has been validated by computer simulation and phantom studies. The results of these validation studies indicate that this new method offers significant improvements in image quality when compared to other reconstruction algorithms, including the filtered backprojection method and the maximum likelihood approach, as well as the Bayesian method without the use of the prior boundary information.     

A novel approach to the estimation of the long-range dependence parameter

A new method to estimate the Hurst parameter of certain classes of random processes is presented. This method applies to Gaussian processes that are either exactly second-order self-similar or fractional ARIMA. The case of the former is of special interest because local area network traffic is well-known to be of this form. Confidence intervals and bias are obtained for the estimates using the new method. The new method is then applied to pseudo-random data and to real traffic data. The performance of the new method is compared to that of the widely-used wavelet method, which demonstrates that the former is much faster and produces much smaller confidence intervals of the long-range dependence parameter.     

Ridgelet域中基于非参数自适应密度估计理论的图像去噪方法

Ridgelet 是一种新的信号分析方法,它适合于具有直线或超平面奇异性的二维信号的描述,目前, 针对特定大小的离散图像,又提出了正交有限Ridgelet变换(FRIT)。该文在有限Ridgelet域中,结合Birge-Massart等提出的非参数自适应估计理论,提出一种新的二维图像去噪方法。实验证明,这种基于Ridgelet与Birge-Massart理论的图像去噪方法,与传统的Wavelet域去噪以及Donoho阈值去噪方法相比,去噪效果更为明显。     

基于模板卷积的野值剔除方法

测量数据中野值的成功剔除是后续数据处理精度的重要保证.针对测量数据前后相关性这一客观事实,并结合最小二乘理论,对前期提出的基于模板卷积的野值剔除方法进行了改进,从理论上分析了该方法的高精度性和高实时性,并进行了仿真实验.仿真结果表明,该方法能有效剔除测量数据中的野值点.     

求解稀疏最小二乘问题的新型Bregman迭代正则化算法

由于允许从少量数据中恢复原始图像或信号的压缩感知的引入,基于l1范数正则化的最优化方法近来越来越受到重视。利用最小二乘问题的一种等价形式和Bregman迭代方法的一些技巧,本文给出了已有A^+线性Bregman迭代方法的一种推导过程。进一步结合不动点连续迭代方法非满值最小二乘问题的等价形式,获得了一种求解带有约束的l1范数最小优化问题的新型算法,并给出了新型算法与A^+线性Bregman迭代算法之间的联系,同时证明了新算法所获得的解是所求问题的一个最优解。新算法与已有A^+算法类似,仅仅需要矩阵向量乘法和压缩算子的计算,从而使得新的算法很容易实现,且运算速度明显快于已有算法。最后,通过数值实验表明,新方法对于稀疏信号的恢复问题与原方法比具有速度快、可有效减少停滞现象等优点。      

畸变不变图像识别算法研究

针对畸变图像难识别的问题,提出了新的基于图像质心和最长边的归一化图像处理算法,并分析比较了极梅林变换、综合识别函数和归一化方法这三种识别算法,并给出了模拟相关结果。分析说明归一化方法能同时实现旋转和比例畸变图像识别.     

一种解决盲区问题的新方法

目前解决合成孔径雷达盲区问题的方法通常是采用可变脉冲重复频率来实现，然而其变化的PRF会导致非均匀采样，增大了后续成像处理的运算复杂度。文中从脉冲波形的角度提出一种解决盲区问题的新方法，并阐述了该方法的原理，最后用仿真结果证实了其正确性。     

一种增强的GEO卫星CDMA通信系统随机接入方式

本文提出了一种适用于GEO卫星CDMA移动通信系统的随机接入方式。该方式参考了S-UMTS中的随机接入方式设计,扩展了其接入帧和接入时隙的长度,并提出了一种新颖的用户随机接入请求的发送策略。通过接入时隙长度的扩展,增大了接入前缀码的个数和前缀的长度,提高了接入消息的扩频增益,从而提高了用户接入的首次捕获概率和接入消息的正确解码概率,降低用户的接入功率,并有效削弱功率攀升问题给系统容量造成的影响。增加了保护间隔的长度,以应对GEO卫星环境下用户之间接入的大时延差问题。本文提出的用户随机接入请求发送策略,有效改善了用户的接入时间性能。     

利用线性扫频信号测量扬声器电声特性

介绍利用线性扫频信号测量扬声器系统的频响特性与指向性,由配备专用声卡的笔记本电脑直接产生与接收声信号。与传统的利用模拟信号进行测量的方法相比,该方法最大的优点在于：通过一次测量可以得到所有需要的信息,从而方便地得到扬声器的电声特性。实验结果证明,该方法简便有效,并有相当的精度,具有实际应用价值。     

基于Zernike-Facet模型和总体最小二乘的弱小目标检测

弱小目标一般是图像局部区域的极值点。针对这个特点,依据二元三次函数的极值理论,该文提出了一种新的弱小目标候选点的检测方法。发展了一种新的图像局部灰度拟合模型,即Zernike-facet模型,模型参数的求解采用比最小二乘(LS)抗噪能力更强的总体最小二乘(TLS)算法。新检测方法通过Zernike-facet模型和TLS对原始图像中每一个像素的局部区域进行曲面拟合,然后在拟合曲面上提取极值点作为目标候选点。仿真表明,新方法在抑制噪声上优于其他常用方法。可见光/红外图像小目标检测实验也证实了新方法的有效性。     

Spread-Spectrum Despreading Without the Code

A new method for despreading direct-sequence spreadspectrum signals, without use of the spreading code, is evaluated by analysis and simulation. The new method exploits the cyclic autocorrelation in place of the conventional autocorrelation, which was used in a prior method. Both methods require that the period of the code be equal to a multiple of the data symbol interval. Broad-band noise and narrowband interference rejection capabilities of both methods are compared. It is shown that the new method, unlike the prior method, can provide substantial immunity to strong narrow-band interference.     

一种抗频偏的时间精同步方法及性能分析

该文导出了互相关时间精同步的性能随频率偏移和信噪比变化的表达式,并提出一种受频偏影响较小的精同步方法。该文对同步性能表达式进行分析,得到在某一频偏下同步序列长度的上限值。新方法将同步序列分段,每段和接收信号分别作互相关,将各段的相关值延时相加作为同步的度量。通过仿真将新方法和其它时间同步方法进行了对比。仿真结果表明,新方法可以大大提高系统抗频偏的能力。     

基于互信息方法的医学图像检索

提出了一种适用于医学图像检索的新方法,即最大互信息方法,使用该方法对超声图像库进行了检索实验,验证了基于最大互信息方法具有良好的检索性能;该方法既能满足位置不变性,旋转不变性和比例不变性,又能避免进行图像分割,从而避免了因图像分割引起的复杂计算,该方法还具有检索速度不受数据库中图像数目影响等优点,也适用于对一般图像进行相似性检索。     

基于形态滤波的基音检测新方法

提出了一种数字形态滤波与数字低通滤波器相结合作为基音检测预处理的基音检测新方法，本方法是线性滤波与非线性滤波相结合的一种新的尝试。实验结果表明，该方法可以得到比传统自相关法和倒谱法更好的结果，尤其是清浊音特征不明显的音段，基音检测的性能更好。     

Analysis of Scattering Characteristics for Strip Grating Sandwiched between Two Dielectric Layers under Oblique Incidence and Its Applications in Spatial Filters and Circular Polarizers

Scattering characteristics of strip grating sandwiched between two dielectric layers in the case of plane-wave arbitrary oblique incidence are carefully investigated by a new method which combines coordinate revolving theory with the rigorous mode matching method. Comparisons between the results obtained with the present method and those given by the other methods verify the effectivity and practicability of the present method. The spatial filter characteristics of the new strip grating structure are given. It shows that the ultra-wideband bandpass characteristics can be realized using the present structure. Besides, a new circular polarizer is proposed. It is indicated that the new circular polarizer can realize complete circular polarization for every frequencies by means of changing the structure parameters of the dielectric uniform layers, which overstep the limitation of single strip that can achieve circular polarization only in a fixed frequency. The present investigation gives some useful guidelines for accurate design of the spatial bandpass filters and circular polarizers.