期刊文献+
共找到2篇文章
< 1 >
每页显示 20 50 100
大颗粒流化床中颗粒反射光纤信号的多重分形特性 被引量:2
1
作者 李晓光 徐德龙 范海宏 《西安交通大学学报》 EI CAS CSCD 北大核心 2005年第11期1259-1263,共5页
采用2 mm直径的光纤探头,对颗粒直径为3.66 mm的二维流化床内颗粒的光纤反射信号进行了采集,并利用小波变换极大模值法对该类信号进行了数值分析,结果表明其具备多重分形特征;给出了多重分形谱图.由谱图分析可知:随颗粒雷诺数Rep的增加... 采用2 mm直径的光纤探头,对颗粒直径为3.66 mm的二维流化床内颗粒的光纤反射信号进行了采集,并利用小波变换极大模值法对该类信号进行了数值分析,结果表明其具备多重分形特征;给出了多重分形谱图.由谱图分析可知:随颗粒雷诺数Rep的增加,床中心处颗粒流动更加规律,而近壁区和中心至壁面半途区的情况正相反;在不同的Rep下,床中心部分颗粒无规则运动程度较高,接近壁面处较低.多重分形谱图分析有望为大颗粒流化床中颗粒运动规律的探测提供一种新的手段. 展开更多
关键词 流化床 大颗粒 小波变换极大模值 多重分形 光纤信号
在线阅读 下载PDF
Comparative analysis of different methods for image enhancement 被引量:4
2
作者 吴笑峰 胡仕刚 +4 位作者 赵瑾 李志明 李劲 唐志军 席在芳 《Journal of Central South University》 SCIE EI CAS 2014年第12期4563-4570,共8页
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. T... 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. 展开更多
关键词 image enhancement wavelet transform histogram equalization unsharp masking(UM) modulus maxl mum threshold
在线阅读 下载PDF
上一页 1 下一页 到第
使用帮助 返回顶部