基于EEMD的水电机组信号分解和频谱分析

采用集合经验模态分解EEMD方法对水电机组多个信号进行分析,结果表明, EEMD分解能够将水电机组信号分解成不同频域内IMF分量分解,各IMF分量与现场振源有一定的关联,具有直观的物理意义,同时对不同工况的信号进行对比分析。     

Effect of dietary linseed on the nutritional value and quality of pork and pork products: Systematic review and meta-analysis

Nutritional quality of pork is a significant factor for consumers' health. Feeding n-3 PUFA to pigs, using linseed, improves pork nutritional quality. A meta-analysis involving 1006 pigs reported in 24 publications was carried out to assess the effects of dietary linseed on alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA) content in muscle and adipose tissue. Data showed positive effects of n-3 PUFA on muscle fatty acid composition: ALA + 137%, EPA + 188%, DPA + 51% and DHA + 12%. Same results were observed in adipose tissue: ALA + 297%, EPA + 149%, DPA + 88% and DHA + 18%. A positive correlation between dietary treatment and ALA and EPA content in muscle (P < 0.001) and adipose tissue (P = 0.036) was observed. A significant association between DPA (P = 0.04) and DHA (P = 0.011) and live weight in muscle was observed. Feeding linseed to pig improves the nutritional pork quality, raising the n-3 PUFA content in muscle and adipose tissue.     

Gear fault identification based on Hilbert–Huang transform and SOM neural network

Gear vibration signals always display non-stationary behavior. HHT (Hilbert–Huang transform) is a method for adaptive analysis of non-linear and non-stationary signals, but it can only distinguish conspicuous faults. SOM (self-organizing feature map) neural network is a network learning with no instructors which has self-adaptive and self-learning features and can compensate for the disadvantage of HHT. This paper proposed a new gear fault identification method based on HHT and SOM neural network. Firstly, the frequency families of gear vibration signals were separated effectively by EMD (empirical mode decomposition). Then Hilbert spectrum and Hilbert marginal spectrum were obtained by Hilbert transform of IMFs (intrinsic mode functions). The amplitude changes of gear vibration signals along with time and frequency had been displayed respectively. After HHT, the energy percentage of the first six IMFs were chosen as input vectors of SOM neural network for fault classification. The analysis results showed that the fault features of these signals can be accurately extracted and distinguished with the proposed approach.     

风电场有功出力的EEMD特性分析

准确、全面的了解风电场有功出力特性是高效利用风能资源的前提,然而风电场出力数据由于其受自然来风影响而存在剧烈的波动性与随机性,针对于此,文章首先在对风电场出力特性进行描述的基础上,引入了自适应的数据分解方法—集合经验模态分解(EEMD),利用EEMD将采样得到的风电场非线性、非稳定有功出力的时间序列数据分解为对应的若干个本征模函数IMF,并通过观察分解所得的本征模函数IMF以及其各分量的波动情况来深入了解采样区域的风电出力特性,以期通过此方法为未来更好、更高效的利用大规模风电提供新的思路。     

基于linux多线程的叠加性电能质量扰动识别系统设计

针对混合电能质量扰动分离和识别问题,提出了一种聚类模态经验分解(EEMD)方法。先对添加高斯白噪声的混合电能质量扰动信号进行扰动分离,再对分离出来的几种单一扰动做Hlibert变换,最后由得到的瞬时频率、幅值特性图谱判断扰动类别。采用Linux下多线程编程方法实现聚类模态经验分解算法,仿真结果表明系统达到了对混合电能质量扰动的分离和识别的目的。     

基于EMD和ICA的单通道语音盲源分离算法

针对单通道语音信号盲分离的问题,结合盲源分离和经验模式分解的优点．提出了一种基于经验模式分解的单通道语音信号源数估计和盲源分离方法。对语音混合信号进行经验模式分解,利用贝叶斯算法估计语音源数目,根据源信号数目重组多通道语音混合信号,并采用独立分量分析实现语音信号的盲分离。仿真实验表明,使用此法能有效地估计通道语音信号源数和分离盲源。     

基于窗口经验模式分解的医学图像增强

提出了基于窗口经验模式分解(WEMD)的医学图像增强算法。用WEMD算法分解医学图像,能够自适应地提取图像的内涵模式函数(IMF)分量。利用IMF分量图像的直方图服从正态分布的特性,结合直方图匹配算法的增强能力处理前几个IMF分量,经处理的IMF分量中的高频细节信息得到增强。将处理后的IMF分量和剩余分量重构,获取增强的医学图像。实验表明,WEMD算法增强效果优于目前的图像增强算法。     

改进的EMD方法在局部放电信号提取中的应用

电力设备内部早期故障产生的局部放电信号很微弱,往往处于强大噪声的包围之中。为了从复杂环境中准确提取局部放电信号,提出应用改进的EMD方法进行局部放电特征信号的提取。首先,对放电信号进行EMD分解;其次,应用能量门限法对EMD分解得到的IMF进行筛选;再次,应用敏感固有模态函数选择法找出敏感IMF,并与局部放电特征信号进行对比。最后,应用结果表明了此方法的可行性与准确性。     

Seasonal changes and muscle type effect on the nutritional quality of intramuscular fat in Mirandesa-PDO veal

The influence of slaughter season and muscle type on the detailed fatty acid composition, including conjugated linoleic acid isomers, and contents of total cholesterol and lipid-soluble antioxidant vitamins (α-tocopherol and β-carotene) in Mirandesa-PDO veal was assessed. Mirandesa purebred calves (n = 29) were raised in a traditional production semi-extensive system, slaughtered in late spring (June) or early autumn (October) and the longissimus lumborum and semitendinosus muscles were sampled for analysis. Although the lipid composition of PDO veal was only slightly affected by the slaughter season, it was markedly changed by the muscle type. However, PDO veal had values of pasture-fed cattle for lipid grass intake indicators, in both seasons and muscles. From a human health standpoint, intramuscular fat in Mirandesa-PDO veal has a high nutritional value throughout the year, with favorable ratios of n− 6/n− 3 and contents of n− 3 PUFA and α-tocopherol, as a result of the beneficial effects of grass feeding.     

基于Android平台的藏文输入法设计与实现

移动互联网时代的到来,人们对智能终端的需求越来越高,实现藏文智能终端的信息化是藏族的人民迫切愿望。文中针对藏文的文本特征,藏文的编码标准,通过研究Android平台的特点及Android平台输入法框架原理,以及Android平台下实现藏文输入的关键技术,设计并实现了一个Android平台下的藏文输入法。