AIM： To evaluate the clinical value of wedge resection at corneal limbus in patients with traumatic corneal scarring and high irregular astigmatism. METHODS： Patients with traumatic corneal astigmatism received wed...AIM： To evaluate the clinical value of wedge resection at corneal limbus in patients with traumatic corneal scarring and high irregular astigmatism. METHODS： Patients with traumatic corneal astigmatism received wedge resection at least 6mo after suture removal from corneal wound. The uncorrected distance visual acuities （UCVA） and best corrected distance visual acuities （BCVA）, pre- and post-operation astigmatism, spherical equivalent （SE）, safety and complications were evaluated. RESULTS： Ten eyes （10 patients） were enrolled in this study. Mean follow-up time after wedge resection was 37.8±15.4mo （range, 20-61mo）. The mean UCVA improved from ＋1.07±0.55 IogMAR to ＋0.43±0.22 IogMAR （P=0.000） and the mean BCVA from ＋0.50±0.30 IogMAR to ＋0.15± 0.17 IogMAR （P=0.000）. The mean astigmatism power measured by retinoscopy was -2.03±2.27 D postoperatively and -2.83±4,52 D preoperatively （P=0.310）. The mean SE was -0.74±1.61 D postoperatively and -0.64±1.89 D preoperatively （P=0.601）. Two cases developed mild pannus near the sutures. No corneal perforation, infectious keratitis or wound gape occurred. CONCLUSION： Corneal-scleral limbal wedge resection with compression suture is a safe, effective treatment for poor patients with high irregular corneal astigmatism after corneal-scleral penetrating injury. Retinoscopy can prove particularly useful for high irregular corneal astigmatism when other measurements are not amenable.展开更多
Square-root cubature Kalman filter (SCKF) is more effective for nonlinear state estimation than an unscented Kalman filter.In this paper,we study the design of nonlinear filters based on SCKF for the system with one s...Square-root cubature Kalman filter (SCKF) is more effective for nonlinear state estimation than an unscented Kalman filter.In this paper,we study the design of nonlinear filters based on SCKF for the system with one step noise correlation and abrupt state change.First,we give the SCKF that deals with the one step correlation between process and measurement noises,SCKF-CN in short.Second,we introduce the idea of a strong tracking filter to construct the adaptive square-root factor of the prediction error covariance with a fading factor,which makes SCKF-CN obtain outstanding tracking performance to the system with target maneuver or abrupt state change.Accordingly,the tracking performance of SCKF is greatly improved.A universal nonlinear estimator is proposed,which can not only deal with the conventional nonlinear filter problem with high dimensionality and correlated noises,but also achieve an excellent strong tracking performance towards the abrupt change of target state.Three simulation examples with a bearings-only tracking system are illustrated to verify the efficiency of the proposed algorithms.展开更多
The special characteristics of slowly moving infrared targets, such as containing only a few pixels,shapeless edge, low signal-to-clutter ratio, and low speed, make their detection rather difficult, especially when im...The special characteristics of slowly moving infrared targets, such as containing only a few pixels,shapeless edge, low signal-to-clutter ratio, and low speed, make their detection rather difficult, especially when immersed in complex backgrounds. To cope with this problem, we propose an effective infrared target detection algorithm based on temporal target detection and association strategy. First, a temporal target detection model is developed to segment the interested targets. This model contains mainly three stages, i.e., temporal filtering,temporal target fusion, and cross-product filtering. Then a graph matching model is presented to associate the targets obtained at different times. The association relies on the motion characteristics and appearance of targets,and the association operation is performed many times to form continuous trajectories which can be used to help disambiguate targets from false alarms caused by random noise or clutter. Experimental results show that the proposed method can detect slowly moving infrared targets in complex backgrounds accurately and robustly, and has superior detection performance in comparison with several recent methods.展开更多
基金Supported by Science and Technology Research Project of Henan Province (No. 102102310117)
文摘AIM： To evaluate the clinical value of wedge resection at corneal limbus in patients with traumatic corneal scarring and high irregular astigmatism. METHODS： Patients with traumatic corneal astigmatism received wedge resection at least 6mo after suture removal from corneal wound. The uncorrected distance visual acuities （UCVA） and best corrected distance visual acuities （BCVA）, pre- and post-operation astigmatism, spherical equivalent （SE）, safety and complications were evaluated. RESULTS： Ten eyes （10 patients） were enrolled in this study. Mean follow-up time after wedge resection was 37.8±15.4mo （range, 20-61mo）. The mean UCVA improved from ＋1.07±0.55 IogMAR to ＋0.43±0.22 IogMAR （P=0.000） and the mean BCVA from ＋0.50±0.30 IogMAR to ＋0.15± 0.17 IogMAR （P=0.000）. The mean astigmatism power measured by retinoscopy was -2.03±2.27 D postoperatively and -2.83±4,52 D preoperatively （P=0.310）. The mean SE was -0.74±1.61 D postoperatively and -0.64±1.89 D preoperatively （P=0.601）. Two cases developed mild pannus near the sutures. No corneal perforation, infectious keratitis or wound gape occurred. CONCLUSION： Corneal-scleral limbal wedge resection with compression suture is a safe, effective treatment for poor patients with high irregular corneal astigmatism after corneal-scleral penetrating injury. Retinoscopy can prove particularly useful for high irregular corneal astigmatism when other measurements are not amenable.
基金supported by the National Natural Science Foundation of China (Nos.60934009,60804064,and 30800248)the China Post-doctoral Science Foundation (No.20100471727)the Science and Technology Department of Zhejiang Province,China (No.2009C34016)
文摘Square-root cubature Kalman filter (SCKF) is more effective for nonlinear state estimation than an unscented Kalman filter.In this paper,we study the design of nonlinear filters based on SCKF for the system with one step noise correlation and abrupt state change.First,we give the SCKF that deals with the one step correlation between process and measurement noises,SCKF-CN in short.Second,we introduce the idea of a strong tracking filter to construct the adaptive square-root factor of the prediction error covariance with a fading factor,which makes SCKF-CN obtain outstanding tracking performance to the system with target maneuver or abrupt state change.Accordingly,the tracking performance of SCKF is greatly improved.A universal nonlinear estimator is proposed,which can not only deal with the conventional nonlinear filter problem with high dimensionality and correlated noises,but also achieve an excellent strong tracking performance towards the abrupt change of target state.Three simulation examples with a bearings-only tracking system are illustrated to verify the efficiency of the proposed algorithms.
基金the National Natural Science Foundation of China(Nos.61273170 and 61503206)the Zhejiang Provincial Natural Science Foundation of China(Nos.LZ16F030002 and LZ15F030001)
文摘The special characteristics of slowly moving infrared targets, such as containing only a few pixels,shapeless edge, low signal-to-clutter ratio, and low speed, make their detection rather difficult, especially when immersed in complex backgrounds. To cope with this problem, we propose an effective infrared target detection algorithm based on temporal target detection and association strategy. First, a temporal target detection model is developed to segment the interested targets. This model contains mainly three stages, i.e., temporal filtering,temporal target fusion, and cross-product filtering. Then a graph matching model is presented to associate the targets obtained at different times. The association relies on the motion characteristics and appearance of targets,and the association operation is performed many times to form continuous trajectories which can be used to help disambiguate targets from false alarms caused by random noise or clutter. Experimental results show that the proposed method can detect slowly moving infrared targets in complex backgrounds accurately and robustly, and has superior detection performance in comparison with several recent methods.
