This letter presents a new one-dimensional chaotic map with infinite collapses. Theoretical analyses show that the map has complicated dynamical behavior and ideal distribution.The map can be applied in chaotic spread...This letter presents a new one-dimensional chaotic map with infinite collapses. Theoretical analyses show that the map has complicated dynamical behavior and ideal distribution.The map can be applied in chaotic spreading spectrum communication and chaotic cipher.展开更多
Iris image segmentation is very important for an iris recognition system.There are always iris noises as eyelash,eyelid,reflection and pupil in iris images.The paper proposes a virtual method of segmentation.By locati...Iris image segmentation is very important for an iris recognition system.There are always iris noises as eyelash,eyelid,reflection and pupil in iris images.The paper proposes a virtual method of segmentation.By locating and normalizing iris images with Gabor filter,we can acquire information of image texture in a series of frequencies and orientations.Iris noise regions are determined based on phase congruency by a group of Gabor filters whose kernels are suitable for edge detection.These regions are filled according to the characteristics of iris noise.The experimental results show that the proposed method can segment iris images effectively.展开更多
AIM： To investigate and review the contrast-enhanced multiple-phase computed tomography （CEMP CT） and magnetic resonance imaging （MRI） findings in patients with pathologically confirmed hepatic epithelioid hemang...AIM： To investigate and review the contrast-enhanced multiple-phase computed tomography （CEMP CT） and magnetic resonance imaging （MRI） findings in patients with pathologically confirmed hepatic epithelioid hemangioendothelioma （HEHE）. METHODS： Findings from imaging examinations in 8 patients （5 women and 3 men） with pathologically confirmed HEHE were retrospectively reviewed （CT images obtained from 7 patients and MR images obtained from 6 patients）. The age of presentation varied from 27 years to 60 years （average age 39.8 years）. RESULTS： There were two types of HEHE： multifocal type （n = 7） and diffuse type （n = 1）. Tn the multifocal-type cases, there were 74 lesions on CT and 28 lesions on MRI with 7 lesions found with diffusion weighted imaging; 18 （24.3%） of 74 lesions on plain CT and 26 （92.9%） of 28 lesions on pre-contrast MRI showed the target sign. On CEMP CT, 28 （37.8%） of 74 lesions appeared with the target sign and a progressive-enhancement rim and 9 （12.2%） of 74 lesions displayed progressive enhancement, maintaining a state of persistent enhancement. On CEMP MRI, 27 （96.4%） of 28 lesions appeared with the target sign with a progressive-enhancement rim and 28 （100%） of 28 lesions displayed progressive-enhancement, maintaining a state of persistent enhancement. In the diffuse-type cases, an enlarged liver was observed with a large nodule appearing with persistent enhancement on CEMP CT and MRI. CONCLUSION： The most important imaging features of HEHE are the target sign and/or progressive en- hancement with persistent enhancement on CEMP CT and MRI. MRI is advantageous over CT in displaying these imaging features.展开更多
This paper first studies the phase errors for fine-resolution spotlight mode SAR imaging and decomposes the phase errors into two kinds, one is caused by translation and the other by rotation. Mathematical analysis an...This paper first studies the phase errors for fine-resolution spotlight mode SAR imaging and decomposes the phase errors into two kinds, one is caused by translation and the other by rotation. Mathematical analysis and computer simulations show the above mentioned motion kinds and their corresponding damages on spotlight mode SAR imaging. Based on this analysis, a single PPP is introduced for spotlight mode SAR imaging with the PFA on the assumption that relative rotation between APC and imaged scene is uniform. The selected single point is used first to correct the quadratic and higher order phase errors and then to adjust the linear errors. After this compensation, the space-invariant phase errors caused by translation are almost corrected. Finally results are presented with the simulated data.展开更多
基金National Natural Science Fundation of China(Grant No. 69735101)
文摘This letter presents a new one-dimensional chaotic map with infinite collapses. Theoretical analyses show that the map has complicated dynamical behavior and ideal distribution.The map can be applied in chaotic spreading spectrum communication and chaotic cipher.
文摘Iris image segmentation is very important for an iris recognition system.There are always iris noises as eyelash,eyelid,reflection and pupil in iris images.The paper proposes a virtual method of segmentation.By locating and normalizing iris images with Gabor filter,we can acquire information of image texture in a series of frequencies and orientations.Iris noise regions are determined based on phase congruency by a group of Gabor filters whose kernels are suitable for edge detection.These regions are filled according to the characteristics of iris noise.The experimental results show that the proposed method can segment iris images effectively.
文摘AIM： To investigate and review the contrast-enhanced multiple-phase computed tomography （CEMP CT） and magnetic resonance imaging （MRI） findings in patients with pathologically confirmed hepatic epithelioid hemangioendothelioma （HEHE）. METHODS： Findings from imaging examinations in 8 patients （5 women and 3 men） with pathologically confirmed HEHE were retrospectively reviewed （CT images obtained from 7 patients and MR images obtained from 6 patients）. The age of presentation varied from 27 years to 60 years （average age 39.8 years）. RESULTS： There were two types of HEHE： multifocal type （n = 7） and diffuse type （n = 1）. Tn the multifocal-type cases, there were 74 lesions on CT and 28 lesions on MRI with 7 lesions found with diffusion weighted imaging; 18 （24.3%） of 74 lesions on plain CT and 26 （92.9%） of 28 lesions on pre-contrast MRI showed the target sign. On CEMP CT, 28 （37.8%） of 74 lesions appeared with the target sign and a progressive-enhancement rim and 9 （12.2%） of 74 lesions displayed progressive enhancement, maintaining a state of persistent enhancement. On CEMP MRI, 27 （96.4%） of 28 lesions appeared with the target sign with a progressive-enhancement rim and 28 （100%） of 28 lesions displayed progressive-enhancement, maintaining a state of persistent enhancement. In the diffuse-type cases, an enlarged liver was observed with a large nodule appearing with persistent enhancement on CEMP CT and MRI. CONCLUSION： The most important imaging features of HEHE are the target sign and/or progressive en- hancement with persistent enhancement on CEMP CT and MRI. MRI is advantageous over CT in displaying these imaging features.
基金Supported by the Aeronautic Scientific Foundation(No.98F5118)
文摘This paper first studies the phase errors for fine-resolution spotlight mode SAR imaging and decomposes the phase errors into two kinds, one is caused by translation and the other by rotation. Mathematical analysis and computer simulations show the above mentioned motion kinds and their corresponding damages on spotlight mode SAR imaging. Based on this analysis, a single PPP is introduced for spotlight mode SAR imaging with the PFA on the assumption that relative rotation between APC and imaged scene is uniform. The selected single point is used first to correct the quadratic and higher order phase errors and then to adjust the linear errors. After this compensation, the space-invariant phase errors caused by translation are almost corrected. Finally results are presented with the simulated data.
