Medical image registration is important in many medical applications. Registration method based on maximization of mutual information of voxel intensities is one of the most popular methods for 3-D multi-modality medi...Medical image registration is important in many medical applications. Registration method based on maximization of mutual information of voxel intensities is one of the most popular methods for 3-D multi-modality medical image registration. Generally, the optimization process is easily trapped in local maximum, resulting in wrong registration results. In order to find the correct optimum, a new multi-resolution approach for brain image registration based on normalized mutual information is proposed. In this method, to eliminate the effect of local optima, multi-scale wavelet transformation is adopted to extract the image edge features. Then the feature images are registered, and the result at this level is taken as the initial estimate for the registration of the original images. Three-dimensional volumes are used to test the algorithm. Experimental results show that the registration strategy proposed is a robust and efficient method which can reach sub-voxel accuracy and improve the optimization speed.展开更多
An experimental study of the dependence of SiO2 waveguide side wall roughness on the etch condi- tions and etch masks in CHF3/O2 based reactive ion etching plasma was reported. When working under standard low-pressure...An experimental study of the dependence of SiO2 waveguide side wall roughness on the etch condi- tions and etch masks in CHF3/O2 based reactive ion etching plasma was reported. When working under standard low-pressure （20mtorr） etching conditions, a novel etch roughening phenomenon has been observed in the plasma, that is, the roughness of the etched front surface increases with the amount of material etched, independent of etch rate, RF power, and gas composition. Besides, the etched underlying side wall will be tapered as the upper SU-8 resist pattern degradation transfers downward. A process using double-layered mask, consisting of SU-8 resist and thin Chromium film, was developed for improving the side wall smoothness. Based on the studies, SiO2/Si channel waveguides with the propagation loss less than 0. 07dB/cm were fabricated at last.展开更多
基金Supported by National Natural Science Foundation of China (No.60373061)Natural Science Foundation of Tianjin (No.04310491R)+1 种基金National Natural Science Foundation of ChinaGeneral Administration of Civil Aviation of China (No.60372048) .
文摘Medical image registration is important in many medical applications. Registration method based on maximization of mutual information of voxel intensities is one of the most popular methods for 3-D multi-modality medical image registration. Generally, the optimization process is easily trapped in local maximum, resulting in wrong registration results. In order to find the correct optimum, a new multi-resolution approach for brain image registration based on normalized mutual information is proposed. In this method, to eliminate the effect of local optima, multi-scale wavelet transformation is adopted to extract the image edge features. Then the feature images are registered, and the result at this level is taken as the initial estimate for the registration of the original images. Three-dimensional volumes are used to test the algorithm. Experimental results show that the registration strategy proposed is a robust and efficient method which can reach sub-voxel accuracy and improve the optimization speed.
文摘An experimental study of the dependence of SiO2 waveguide side wall roughness on the etch condi- tions and etch masks in CHF3/O2 based reactive ion etching plasma was reported. When working under standard low-pressure （20mtorr） etching conditions, a novel etch roughening phenomenon has been observed in the plasma, that is, the roughness of the etched front surface increases with the amount of material etched, independent of etch rate, RF power, and gas composition. Besides, the etched underlying side wall will be tapered as the upper SU-8 resist pattern degradation transfers downward. A process using double-layered mask, consisting of SU-8 resist and thin Chromium film, was developed for improving the side wall smoothness. Based on the studies, SiO2/Si channel waveguides with the propagation loss less than 0. 07dB/cm were fabricated at last.
