Design of a compact dual‐band folded‐waveguide bandpass filter using multilayer waveguide resonators

A novel compact dual‐band bandpass filter based on multilayer folded‐waveguide (FWG) structure is presented in this article.In this design, slots are used to realize direct coupling between adjacent resonators and apertures are adopted to implement cross coupling between non‐adjacent resonators.A new technique of external quality factor of FWG resonator and coupling coefficients between different resonators are studied using full‐wave simulator. In order to demonstrate the proposed technique, a four‐pole dual‐band bandpass filter is designed, fabricated and measured using vector network analyzer. Measurement results which are well agreed with simulation results are presented. Moreover, four‐pole substrate integrated folded waveguide SIFW dual‐band bandpass filter, using two layers of slotted folded waveguide resonators, is demonstrated. The proposed filter has a compact size and it is excellent candidate for the application of wireless communication systems. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:780–788, 2015.     

基于小波变换的卡尔曼滤波动力电池SOC估算

混合动力电动汽车的动力电池和电池管理系统的工程实际应用环境是非常恶劣的,导致信号采样过程中包含大量的系统噪声和测量噪声.因此,提出一种基于小波变换的卡尔曼滤波动力电池SOC估算方法,通过在一系列充放电实验所建立的动力电池系统模型上,利用小波变换自相似过程的去相关作用和多尺度多分辨的特性对噪声进行抑制,实时对测量信号多尺度滤波分解,再采用卡尔曼滤波的迭代递推的线性无偏最小方差估计特性对电池SOC进行估算.实验结果表明,提出的基于小波变换的卡尔曼滤波SOC估算方法效果优于标准的卡尔曼滤波算法,在实际工况中,具有较强的适应性.     

Particle filters and occlusion handling for rigid 2D–3D pose tracking

In this paper, we address the problem of 2D–3D pose estimation. Specifically, we propose an approach to jointly track a rigid object in a 2D image sequence and to estimate its pose (position and orientation) in 3D space. We revisit a joint 2D segmentation/3D pose estimation technique, and then extend the framework by incorporating a particle filter to robustly track the object in a challenging environment, and by developing an occlusion detection and handling scheme to continuously track the object in the presence of occlusions. In particular, we focus on partial occlusions that prevent the tracker from extracting an exact region properties of the object, which plays a pivotal role for region-based tracking methods in maintaining the track. To this end, a dynamical choice of how to invoke the objective functional is performed online based on the degree of dependencies between predictions and measurements of the system in accordance with the degree of occlusion and the variation of the object’s pose. This scheme provides the robustness to deal with occlusions of an obstacle with different statistical properties from that of the object of interest. Experimental results demonstrate the practical applicability and robustness of the proposed method in several challenging scenarios.     

Fast two-dimensional weighted least squares techniques for the design of two-dimensional finite impulse response filters

This paper focuses on the design of two-dimensional (2D) quadrantally symmetric finite impulse response (FIR) filters, and presents three very efficient algorithms for the weighted least squares (WLS) design with a weight matrix that assigns four different weights to four different frequency bands. The first algorithm seeks for iterative solutions to the matrix equation describing the optimality condition of the design problem. The second algorithm aims at the limit solution of the solution sequence to the first algorithm, analytically obtained by using matrix diagonalization techniques. The third algorithm belongs to the category of iterative reweighting techniques. It uses the second algorithm as its iteration core, and aims at reducing the maximum magnitude error of the filter by iteratively adjusting the four entry values of the weight matrix. Design examples are provided to demonstrate the performance of the proposed algorithms.     

基于小波包变换与Wiener滤波的SMT焊点图像去噪技术

针对目前SMT(surface mount technology)焊点图像去噪效果不理想的问题,提出了一种基于小波包变换与wiener滤波的SMT焊点图像去噪新方法.利用小波包对图像进行分解,可以同时对SMT焊点图像的低频和高频部分进行多层分解,有利于保留图像信息,减少噪声对图像的影响.通过对图像的小波包系数的分析,对小波包树高频系数进行Wiener滤波,保留低频系数;然后进行小波包反变换,重构得到SMT焊点去噪后图像.实验表明,提出的方法不仅可以有效地去除SMT焊点图像的噪声,而且能很好地保留原图像的边缘信息,与传统方法相比,去噪性能和去噪声效果有一定的提高.     

基于小波域的模糊增强算法

在小波域上用模糊增强算法实现图像的增强,这是涉足较少的一个领域,以前基本上都是分开研究图像的增强算法.在小波域上增强图像,小波基的选择是很重要的一个问题.给出了选择小波基的标准,针对本算法,使用了相对较好的bior4.4小波基,对模糊增强算法,在传统的模糊增强算法基础上,提出了一种改进算法.它主要是对隶属度函数的修改,改进后的隶属度函数取值范围更广泛,适应性更强.所有的算法都经过了Matlab编程,实验表明,增强以后的图像能够显示更多的细节,图像变得更加清晰,可以得出本算法基本上是成功的.     

第二代小波及压缩算法在数据处理中的应用

为消除误差和随机干扰对测量数据的影响,提出利用第二代小波提升算法对原始测量数据进行去噪处理,再利用基于第二代小波原理的数据压缩算法对测量数据进行不失真压缩。两种方法结合运用,可以在保留数据特征及精度的基础上,降低数据量,提高工作的速度和质量。     

一种基于区域分割的图像融合方法

提出了一种基于区域分割的图像融合方法.首先,通过对原图像进行小波分解得到其近似子图和细节子图,对细节子图运用分水岭分割法获得每一层的分割子图用于引导融合过程.然后在分割区域中对原图像小波系数的活动水平及匹配度进行度量,并在组合细节子图系数和近似子图系数的过程中分别采用最大值法则和加权平均法则.最后,通过逆小波变换得到最...     

一种新型环谐振器在带通滤波器中的应用

本文设计了一种新型四分之一波长侧耦合线双模环形谐振器。根据滤波器的指标要求：中心频率、带宽、传输零点频率以及通带插八损耗,综合设计得出谐振器参数。将这种谐振器应用到传统的平行耦合微带线带通滤波器中,大大提高了滤波器的频率选择性。     

基于小波阈值的sEMG信号消噪方法研究

在表面肌电（sEMG）信号采集过程中,不可避免的会出现噪声,特别是人体运动时,肌肉动态收缩,采集的结果含噪就会更多。针对含噪情况,提出基于小波阈值的sEMG信号消噪方法。通过选择肌电信号的采集位置,在采用高精度的肌电采集系统的基础上,采集正常行走过程中胫骨前肌的sEMG信号,利用matlab小波工具箱,用dbN小波函数进行分解后,用detcoef函数提取不同尺度的细节系数,将与噪声相关的细节系数进行强制阈值消噪,对信号相关的细节系数用minimaxi阈值规则进行软阈值消噪,并与分层阚值得到的降噪信号进行比较,分层阈值得到的降噪信号过于光滑,降噪后的信号能量保留成份仅为46．48％,失去了原信号本身的一些信息。而采用软闯值消噪,不仅较好的去除了噪声,而且与原信号保持了很好的相似性,能量保留成份达到86．38％,说明比分层阈值具有更好的消噪效果。