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	A Local Image Enhancement Method Based on Adjacent Pixel Gray Order-preserving Principle 会议论文 OAI收割 5th International Symposium on Photoelectronic Detection and Imaging (ISPDI) - Infrared Imaging and Applications, Beijing, June 25-27, 2013 作者: Fan XP(范晓鹏); Cai TF(蔡铁峰); Zhu F(朱枫) 收藏 \| 浏览/下载：45/0 \| 提交时间：2013/12/26 The paper is committed in local image enhancement. At first, the authors propose an adjacent pixel gray order-preserving principle. Adjacent pixel gray order-preserving principle is the basement of local enhancement method which ensures that there is no distortion in processed image. And then, the authors propose an iterative algorithm, which could stretch gray-scale difference of adjacent pixels in premise of not changing gray magnitude relationship between adjacent pixels. At last, the authors propose a totally reference image quality assessment method based on adjacent pixel gray order-preserving principle. According to this quality assessment method, the authors made a set of comparative experiments with local histogram equalization and method. Experimental results show that the proposed enhancement method can get higher score and provide better visual effects, fully demonstrating its effectiveness. According to this quality assessment method, the proposed method shows a good effectiveness, through experimental results and comparison with local histogram equalization method.
	An appraisal method of dynamic interpolation error for high precision encoder (EI CONFERENCE) 会议论文 OAI收割 2011 International Conference on Electronics and Optoelectronics, ICEOE 2011, July 29, 2011 - July 31, 2011, Dalian, China 作者: Wan Q.-H.; Liu C.-X.; Liu C.-X. 收藏 \| 浏览/下载：30/0 \| 提交时间：2013/03/25 This paper introduces an appraisal method of the dynamic interpolation error for the high precision encoder (Lissajou pattern calculation method). When the encoder is rolling two groups of fine photoelectric signals whose phase difference are /2 can be collected using data collected car. The shape and position deviation can be obtained through the comparison between Lissajou charts and the standard circle. Then dynamic interpolation error can be calculated out directly. This method is immune to the influence of encoder's speed and has no rigid demand to the test circumstances and test devices. The experimental results indicate that this method is feasible and important to the encoder's dynamic interpolation error checking. 2011 IEEE.
	Analysis of a diffractive microlens using the finite-difference time-domain method (EI CONFERENCE) 会议论文 OAI收割作者: Liu Y.; Liu H.; Liu H.; Liu H.; Liu Y. 收藏 \| 浏览/下载：31/0 \| 提交时间：2013/03/25 The finite-difference time-domain (FDTD) method is used as rigorous electromagnetic analysis model to calculate the field for a diffractive microlens (DML). The FDTD is used for the entire solution rather than using a near- to far-field propagation method to obtain the far-field energy distribution thus all the results are vector based. We derived a formula to calculate the magnitude of electric field which is time dependent and can be used to graphically show the light wave propagation and focusing process through a DML. Both the comparison and the integral methods are presented to obtain wave amplitude in full solution space and the distribution of light energy behind a DML is illustrated based on the wave amplitude. The formula of diffractive efficiency of the DML is derived from a time-averaged Ponyting vector which can indicate the propagation direction of light energy. Application of these formulations in the analysis of a DML example demonstrates the high accuracy and efficiency of our method. 2010 Society of Photo-Optical Instrumentation Engineers.
	A new method for comparing Zernike circular polynomials with Zernike annular polynomials in annular pupils (EI CONFERENCE) 会议论文 OAI收割 2010 International Conference on Computer, Mechatronics, Control and Electronic Engineering, CMCE 2010, August 24, 2010 - August 26, 2010, Changchun, China Jing S.; Dongmei M. 收藏 \| 浏览/下载：36/0 \| 提交时间：2013/03/25 To compare the difference between Zernike annular polynomial and Zernike circular polynomial an approximate mathematic relationship between Zernike annular polynomial coefficients and SEIDEL coefficients is proposed. A new method is applied in comparing experiment. For real interferometric data of annular wave front the SEIDEL aberration calculated in different ways is removed from the original wave front. Residual astigmatism aberration in annular polynomial way is close to zero but defocus and sphere aberration are 0.002709 -0.00182. The residual SEIDEL using annular polynomial is least. Data used in comparison shows that Zernike annular polynomial is more accurate and meaningful for the decomposition of aberrations and the calculation of Seidel aberrations in annular pupil. The calculation in astigmatism aberration is most accurate and those in defocus and sphere aberration are least accurate when the first 9 terms are used in approximate solving SEIDEL. More coefficients are needed to obtain the real SEIDEL. 2010 IEEE.
	DIFFERENCES AMONG DIFFERENT DATABASES IN THE NUMBER OF TROPICAL CYCLONES FORMING OVER THE WESTERN NORTH PACIFIC 期刊论文 OAI收割 JOURNAL OF TROPICAL METEOROLOGY, 2010, 卷号: 16, 期号: 4, 页码: 341-347 Wu, SA; Kong, HJ; Wu, H 收藏 \| 浏览/下载：20/0 \| 提交时间：2011/07/03 statistical characters difference comparison tropical cyclone frequency non-homogeneity
	Rigorous vector analysis of diffractive microlens by using of finitedifference time-domain method (EI CONFERENCE) 会议论文 OAI收割 2009 International Conference on Optical Instruments and Technology, OIT 2009, October 19, 2009 - October 22, 2009, Shanghai, China 作者: Liu Y.; Liu H.; Liu H.; Liu H.; Liu Y. 收藏 \| 浏览/下载：36/0 \| 提交时间：2013/03/25 We use finite difference time domain (FDFD) method as rigorous vector analysis model to simulate the focusing process of diffractive microlens (DML). Differing with most analysis model which the near field distributions are calculated by FDTD and then far field are obtained by using of propagation method we obtain the fields in whole computational space by using of FDTD only. The advantages are that all the results are vector based and the computational time is saved greatly. In this paper we present two methods to obtain wave amplitude one is comparison method and the other is integral method. Depending on wave amplitude in the whole computational space one can conveniently obtain distributions of electric field intensity and calculate the time-average Poynting vector. We also present the formulation for calculating diffractive efficiency of DML based on time-average Poynting vector which denotes energy flow. As demonstration a DML is analyzed by using of these algorithms. The time depended graphic results of FDTD show the process of wave propagation. The distribution of electric field intensity illustrates the focusing of the normal incident light. The focus pattern in the focal plane is also show. The diffractive efficiency of the DML is calculated by using of the energy flow method in this paper. The results show the high accuracy and efficiency of the model. 2009 SPIE.
	Test of an off-axis asphere by subaperture stitching interferometry (EI CONFERENCE) 会议论文 OAI收割 4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, November 19, 2008 - November 21, 2008, Chengdu, China 作者: Zheng L.-G.; Zhang X.-J.; Zhang Z.-Y.; Zhang Z.-Y.; Deng W.-J. 收藏 \| 浏览/下载：58/0 \| 提交时间：2013/03/25 A new method combined subaperture stitching with interferometry(SSI) is introduced. It can test large and off-axis aspheric surfaces without the aid of other null optics. In this paper the basic principle and theory of the technique are analyzed. The synthetical optimization stitching model and effective stitching algorithm are established based on homogeneous coordinates transformation and simultaneous least-squares method. The software of SSI is devised and the prototype for testing of large aspheres by SSI is designed and developed. An off-axis asphere with the aperture of 376mm188mm is tested by this method. For comparison and validation and the difference of PV and RMS error between them is 0.047 e and 0.006 e the asphere is also tested by null compensation.The synthesized surface profile is consistent to that ofthe entire surface from null test respectively. So it provides another quantitative measurement for testing large aspheric surfaces and off-axis aspheres besides null-compensation. 2009 SPIE.
	The analysis and design of low velocity estimation based on observer (EI CONFERENCE) 会议论文 OAI收割 2009 IEEE International Conference on Automation and Logistics, ICAL 2009, August 5, 2009 - August 7, 2009, Shenyang, China 作者: Wang D.; Zhang S. 收藏 \| 浏览/下载：37/0 \| 提交时间：2013/03/25 Low velocity servo system needs precision velocity estimation. An observer for low velocity estimation was proposed in this paper. First the source of low velocity estimation errors and the shortcomings of the single period difference were analyzed. The relationship between the estimation accuracy and estimator's frequency characteristics was concluded. Then the structure of the observer was proposed. Frequency characteristics were used to design the compensator which can stabilize the observer. The stability of the observer was also discussed. At last the observer's estimation accuracy was evaluated through a quantitative comparison. The results of simulation and experiment have shown that the quantized error in velocity estimation decreases dramatically when a velocity observer is used. Compared with some commonly-used estimators the phase lag accompanying the observer is much less. 2009 IEEE.