Image matching refers to the process of matching two or more images obtained at different time,different sensors or different conditions through a large number of feature points in the image.At present,image matching ...Image matching refers to the process of matching two or more images obtained at different time,different sensors or different conditions through a large number of feature points in the image.At present,image matching is widely used in target recognition and tracking,indoor positioning and navigation.Local features missing,however,often occurs in color images taken in dark light,making the extracted feature points greatly reduced in number,so as to affect image matching and even fail the target recognition.An unsharp masking(USM)based denoising model is established and a local adaptive enhancement algorithm is proposed to achieve feature point compensation by strengthening local features of the dark image in order to increase amount of image information effectively.Fast library for approximate nearest neighbors(FLANN)and random sample consensus(RANSAC)are image matching algorithms.Experimental results show that the number of effective feature points obtained by the proposed algorithm from images in dark light environment is increased,and the accuracy of image matching can be improved obviously.展开更多
近日,佳能(中国)发布了恒定F2.8光圈L级旗舰远摄变焦镜头RF100-300mm F2.8 L IS USM。这支镜头的诞生进一步拓展了佳能RF远摄镜头阵营。在单反相机时代,佳能EF 300mm f/2.8L IS II USM镜头以其尖端技术、高画质得到了专业摄影师和摄影...近日,佳能(中国)发布了恒定F2.8光圈L级旗舰远摄变焦镜头RF100-300mm F2.8 L IS USM。这支镜头的诞生进一步拓展了佳能RF远摄镜头阵营。在单反相机时代,佳能EF 300mm f/2.8L IS II USM镜头以其尖端技术、高画质得到了专业摄影师和摄影爱好者的一致好评。现在,借助先进的RF卡口,佳能将被看作是尖端技术和高画质标杆的EF 300mm f/2.8L IS II USM“移植”到了这支起步100mm焦距、具有3倍变焦倍率的RF100-300mm F2.8 L IS USM上,使RF100-300mm F2.8 L IS USM这支恒定F2.8大光圈L级远摄变焦镜头不仅具备可匹敌F2.8大光圈定焦镜头的高画质,还可覆盖100-300mm宽广焦距范围。它将高表现力与便利性集于一身,在拍摄室内外体育比赛、T台时装秀、红毯走秀、飞机火车、野生动物等题材和新闻报道中可以大显身手。展开更多
A novel variable camber wing driven by ultrasonic motors is proposed.Key techniques of distributed layout of drive mechanisms,coordination control of distributed ultrasonic motors as well as novel flexible skin underg...A novel variable camber wing driven by ultrasonic motors is proposed.Key techniques of distributed layout of drive mechanisms,coordination control of distributed ultrasonic motors as well as novel flexible skin undergoing one-dimensional morphing are studied.The system integration of small variable camber wing is achieved.Distributed layout of parallelogram linkages driven by geared ultrasonic motors is adopted for morphing,aimed at reducing the load for each motor and producing various aerodynamic configurations suitable for different flying states.Programmable system-on-chip(PSoC)is used to realize the coordination control of the distributed ultrasonic motors.All the morphing driving systems are assembled in the interior of the wing.The wing surface is covered with a novel smooth flexible skin in order to maintain wing shape and decrease the aerodynamic drag during morphing.Wind tunnel test shows that the variable camber wing can realize morphing under low speed flight condition.Lift and drag characteristics and aerodynamic efficiency of the wing are improved.Appropriate configurations can be selected to satisfy aerodynamic requirements of different flight conditions.The study provides a practical application of piezoelectric precision driving technology in flow control.展开更多
基金Supported by the National Natural Science Foundation of China(No.61771186)the Heilongjiang Provincial Natural Science Foundation of China(No.YQ2020F012)the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(No.UNPYSCT-2017125).
文摘Image matching refers to the process of matching two or more images obtained at different time,different sensors or different conditions through a large number of feature points in the image.At present,image matching is widely used in target recognition and tracking,indoor positioning and navigation.Local features missing,however,often occurs in color images taken in dark light,making the extracted feature points greatly reduced in number,so as to affect image matching and even fail the target recognition.An unsharp masking(USM)based denoising model is established and a local adaptive enhancement algorithm is proposed to achieve feature point compensation by strengthening local features of the dark image in order to increase amount of image information effectively.Fast library for approximate nearest neighbors(FLANN)and random sample consensus(RANSAC)are image matching algorithms.Experimental results show that the number of effective feature points obtained by the proposed algorithm from images in dark light environment is increased,and the accuracy of image matching can be improved obviously.
文摘近日,佳能(中国)发布了恒定F2.8光圈L级旗舰远摄变焦镜头RF100-300mm F2.8 L IS USM。这支镜头的诞生进一步拓展了佳能RF远摄镜头阵营。在单反相机时代,佳能EF 300mm f/2.8L IS II USM镜头以其尖端技术、高画质得到了专业摄影师和摄影爱好者的一致好评。现在,借助先进的RF卡口,佳能将被看作是尖端技术和高画质标杆的EF 300mm f/2.8L IS II USM“移植”到了这支起步100mm焦距、具有3倍变焦倍率的RF100-300mm F2.8 L IS USM上,使RF100-300mm F2.8 L IS USM这支恒定F2.8大光圈L级远摄变焦镜头不仅具备可匹敌F2.8大光圈定焦镜头的高画质,还可覆盖100-300mm宽广焦距范围。它将高表现力与便利性集于一身,在拍摄室内外体育比赛、T台时装秀、红毯走秀、飞机火车、野生动物等题材和新闻报道中可以大显身手。
基金supported by the National Natural Science Foundation of China(Nos.50905085,91116020)the Aviation Science Foundation of China(No.20100112005)
文摘A novel variable camber wing driven by ultrasonic motors is proposed.Key techniques of distributed layout of drive mechanisms,coordination control of distributed ultrasonic motors as well as novel flexible skin undergoing one-dimensional morphing are studied.The system integration of small variable camber wing is achieved.Distributed layout of parallelogram linkages driven by geared ultrasonic motors is adopted for morphing,aimed at reducing the load for each motor and producing various aerodynamic configurations suitable for different flying states.Programmable system-on-chip(PSoC)is used to realize the coordination control of the distributed ultrasonic motors.All the morphing driving systems are assembled in the interior of the wing.The wing surface is covered with a novel smooth flexible skin in order to maintain wing shape and decrease the aerodynamic drag during morphing.Wind tunnel test shows that the variable camber wing can realize morphing under low speed flight condition.Lift and drag characteristics and aerodynamic efficiency of the wing are improved.Appropriate configurations can be selected to satisfy aerodynamic requirements of different flight conditions.The study provides a practical application of piezoelectric precision driving technology in flow control.
