基于灰度化权值调整的水下彩色图像分割

针对传统自适应阈值法在水下图像分割过程中存在目标与背景粘连等问题,提出一种基于灰度化权值调整的水下彩色图像分割方法。区别于传统阈值分割方法中灰度化权值固定且研究如何确定合适阈值的思路,研究灰度化权值调整方法。本文方法利用统计得到的图像灰度信息来确定不同通道内目标与背景间灰度级差异性的大小,提高差异性较大通道的比例,以增强灰度化后图像中目标与背景的对比度,同时减小差异性较小通道的比例,以降低其对灰度化结果的干扰,对灰度化后的图像进行阈值分割得到最终分割结果。针对水下作业的时序列图像,设计了两步序列图像处理方式来降低耗时。通过4组水下对比实验以及耗时实验对方法的有效性进行了验证。     

一种门限可追踪的匿名签密方案

为解决匿名签密算法中签密者身份的追踪问题,提出了一种门限可追踪的匿名签密方案.该方案借助范德蒙行列式生成成员的公钥和私钥,通过在匿名签密过程中附加一些与签密者身份相关的额外信息,实现签密者身份的门限追踪.在不可分模型下,证明了该方案满足匿名性、门限可追踪性、不可伪造性和不相关性.     

自适应熵疫苗算子的免疫图像分割方法

本文针对二维熵图像分割算法存在计算量巨大的问题,基于免疫调节机制,设计了一种新的图像分割方法．该方法利用免疫疫苗理论,并与熵理论相结合,提出了熵疫苗算子．熵疫苗作为抗体疫苗进行选择,通过熵运算,提取更新疫苗库,从而使得最优分割阈值的形成及疫苗库的更新具有自适应性,疫苗的选择更加准确有效．仿真实验表明熵疫苗算子加快了算法的搜索速度、提高了算法的适应性．该算法对复杂图像具有良好分割效果和较强的实时处理能力．     

基于小波变换的电能质量监测

针对噪声系数的幅度随着尺度增加而减小的特点,提出了一种改进的基于小波分解层数的波段自适应降噪算法.利用Matlab仿真软件建立了电压暂降的系统模型,运用小波分析的方法对污染白噪声的电压暂降信号进行了时频分析和降噪处理,分析了软硬阈值降噪方法.实验结果表明,该方法通过调整两个可调参数获得较优的小波系数阈值估计,与常见的三种典型算法相比不仅较好地去除了噪声干扰,且信噪比更高,均方误差更小,同时具有更优的信息保全能力.     

Effects of expanding zone parameters of vacuum dust suction mouth on flow simulation results

Based on the parametric analysis of the expanding zone of the vacuum dust suction mouth, the flow in the vacuum dust suction mouth was simulated by computational fluid dynamics （CFD） software, Fluent. The effects of the expanding zone parameters on flow simulation were analyzed. The results show that simulation effects depend on threshold values of the expanding zone parameters of the dust suction mouth, and the threshold values of the expanding zone can be obtained according to the different structures of the vacuum dust suction mouth and be selected as the geometric parameters in calculating, and also corners of the expanding zone make unobvious difference in calculation accuracy and in computational efficiency compared with no corner. The simulation results provide practical guidance to the flow simulation on the dust suction mouth.     

Comparative analysis of different methods for image enhancement

Image enhancement technology plays a very important role to improve image quality in image processing. By enhancing some information and restraining other information selectively, it can improve image visual effect. The objective of this work is to implement the image enhancement to gray scale images using different techniques. After the fundamental methods of image enhancement processing are demonstrated, image enhancement algorithms based on space and frequency domains are systematically investigated and compared. The advantage and defect of the above-mentioned algorithms are analyzed. The algorithms of wavelet based image enhancement are also deduced and generalized. Wavelet transform modulus maxima（WTMM） is a method for detecting the fractal dimension of a signal, it is well used for image enhancement. The image techniques are compared by using the mean（μ）,standard deviation（？）, mean square error（MSE） and PSNR（peak signal to noise ratio）. A group of experimental results demonstrate that the image enhancement algorithm based on wavelet transform is effective for image de-noising and enhancement. Wavelet transform modulus maxima method is one of the best methods for image enhancement.     

Effective model based fault detection scheme for rudder servo system

The inherent nonlinearities of the rudder servo system（RSS） and the unknown external disturbances bring great challenges to the practical application of fault detection technology. Modeling of whole rudder system is a challenging and difficult task. Quite often, models are too inaccurate, especially in transient stages. In model based fault detection, these inaccuracies might cause wrong actions. An effective approach, which combines nonlinear unknown input observer（NUIO） with an adaptive threshold, is proposed. NUIO can estimate the states of RSS asymptotically without any knowledge of external disturbance. An adaptive threshold is used for decision making which helps to reduce the influence of model uncertainty. Actuator and sensor faults that occur in RSS are considered both by simulation and experimental tests. The observer performance, robustness and fault detection capability are verified. Simulation and experimental results show that the proposed fault detection scheme is efficient and can be used for on-line fault detection.     

基于纹理结构异常的织物疵点检测算法研究

提出了一种基于织物纹理结构异常的织物疵点检测算法。首先计算代表正常纹理的主邻域结构图;其次通过比较每个像素的邻域结构图与主邻域结构图的差异来定义该像素的显著性,进而得到显著图;最后采用迭代最优阈值分割方法对显著图进行分割得到疵点区域。试验证明,该算法操作简单、计算速度快、鲁棒性强,具有较强的自适应性。     

基于动态双门限和D-S证据理论的合作频谱感知算法

针对传统能量检测算法门限设置单一且不适应感知信道环境差异的问题,为了提高合作频谱感知结果的可靠性,减小网络开销和融合中心计算的负担,提出了将动态双门限能量检测和D-S证据理论相结合的合作频谱感知算法.在进行本地感知时,该算法可以让认知用户通过双门限能量检测方法直接得到本地判决结果,同时根据信道环境的变化自适应调整双门限值,并在双门限内使用D-S证据理论,感知双门限内未判决结果的信任度函数,将其发往融合中心,这样可以减少融合中心的计算量以及传输带来的网络开销.仿真结果表明,双门限D-S证据理论的融合结果要优于D-S证据理论和OR准则.     

基于双线性对的门限代理盲多重签名方案 *

该方案是门限代理多重签名与盲签名的有机集成 ,既解决了代理签名方案中代理签名人权利过于集中的问题 ,又通过盲签名实现了签名的匿名性和不可追踪性。在该数字签名方案的基础上 ,采用双线性对的签名和验证方式 ,提出了基于双线性对的门限代理盲多重签名方案 ,极大地提高了门限代理盲多重签名的安全性和实现速度。