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Simulation study of phase retrieval for hard X-ray in-line phase contrast imaging

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Science china(Physics,Mechanics & Astronomy) 2005年第4期48卷 450-458页

作者： YU Bin1,2, PENG Xiang1,2, TIAN Jindong1, NIU Hanben1, DIAO Luhong3 & LI Hua3 1. key laboratory of optoelectronic Devices and Systems of ministry of education, Institute of optoelec- tronics, Shenzhen University, Shenzhen 518060, china 2. State key laboratory of Precision Measuring technology and Instruments, tianjin University, tianjin 300072,china 3. key laboratory of Intelligent information Processing, Institute of Computing technology, Chinese Academy of Sciences, Beijing 100080,china key laboratory of optoelectronic Devices and Systems of ministry of education Institute of Optoelectronics Shenzhen University Shenzhen China State key laboratory of Precision Measuring technology and Instruments Tianjin University Tianjin China key laboratory of Intelligent information Processing Institute of Computing Technology Chinese Academy of Sciences Beijing China

Two algorithms for the phase retrieval of hard X-ray in-line phase contrast imaging are presented. One is referred to as Iterative Angular Spectrum Algorithm (IASA) and the other is a hybrid algorithm that combines IASA with TIE (transport of intensity equation). The calculations of the algorithms are based on free space propagation of the angular spectrum. The new approaches are demonstrated with numerical simulations. Comparisons with other phase retrieval algorithms are also performed. It is shown that the phase retrieval method combining the IASA and TIE is a promising technique for the application of hard X-ray phase contrast imaging.

关键词： X-ray optics, phase contrast imaging, phase retrieval, angular spectrum, hard X-ray.

A study on odd-parity high-lying states of the Sm atom with three-color resonant excitation

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Science china(Physics,Mechanics & Astronomy) 2011年第6期54卷 1124-1130页

作者： LI Ming 1,2,DAI ChangJian 1,2 & XIE Jun 1,2 1 key laboratory of Display Materials and Photoelectric Devices,ministry of education,tianjin 300191,china 2 School of Science,tianjin University of technology,tianjin 300384,china key laboratory of Display Materials and Photoelectric Devices Ministry of Education Tianjin China School of Science Tianjin University of Technology Tianjin China

The odd-parity high-lying states of the Sm atom are investigated systematically by a three-color resonant excitation scheme with two different excitation *** two intermediate states,4f 6 6s7s 7 F 0 and 4f 6 6s7s 7 F 1 are employed for paths I and II,***-seven bound states are detected with paths I and II in the energy range between 44188 and 45515 cm 1,while 64 autoionizing states are found in the energy range from 45528 to 45761 cm *** only the level energies of all observed states,but also the line widths of autoionizing states are *** possible impact of configuration interaction on the line shape of autoionizing states is also *** addition,the total angular momentum is assigned uniquely to most of the states,whereas the information about the relative line intensity of all states is also presented.

关键词： high-lying states odd-parity the Sm atom resonant excitation

Iris Localization Algorithm Based on Improved Generalized Symmetry Transform

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Transactions of tianjin University 2004年第4期10卷 259-264页

作者：左坤隆刘文耀朱昊王晓东 School of Precision Instruments and opto-electronics Engineering Tianjin University Tianjin 300072 China key laboratory of opto-electronics information and Technical Science (tianjin University) Ministry of Education Tianjin 300072 China

Accuracy and fastness of iris localization are very important in automatic iris recognition. A new fast iris localization algorithm based on improved generalized symmetry transform (GST) was proposed by utilizing (iris) symmetry. GST was improved in three aspects:1) A new distance weight function is defined. The new weight function, which is effective in iris localization, utilized the characteristic of irises that the iris is a circular object and it has one inner boundary and one outer boundary. 2) Each calculation of the symmetry measurement of a pair of symmetry points was performed by taking one point of a pair as the starting point of the transformation. This is the most important reason for fast iris localization,due to which, repetitious computation was largely excluded. 3) A new phase weight function was proposed to adjust GST to locate circle target much better because the inner part of iris is darker than the outer part. The edge map of iris image was acquired and GST was only implemented on the edge point, which decreased computation without loss of accuracy. The modification of distance weight function and phase weight function leads to the accuracy of localization, and other ideas speed up the localization. Experiments show that the average speed of new algorithm is about 7.0—8.5 times as high as traditional ones including integro-differential operator and Hough transform method.

关键词： iris recognition edge detection morphology generalized symmetry transform (GST)

Design and Implementation of a Virtual Multi-channel Optical Ring

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Chinese Journal of Lasers 2001年第6期10卷 12-17页

作者： JING Wencai ZHOU Ge ZHANG Yimo LI Haifeng ZHANG Hongxia (College of Precision Instrument & opto-electronics Engineering, tianjin University, key laboratory of optoelectronics information Technical Science, EMC, tianjin 300072, china) 天津大学精密仪器与光电子工程学院教育部光电信息技术科学重点实验室天津 300072

The hardware and the communication protocol of a scalable optical ring have been designed. A hardware routing has been achieved on the network interface card to minimize data packet communication latency and a simplified communication protocol has been designed to reduce communication overheads. To reduce the data packet blocking probability and have a more efficient usage of the data link layer bandwidth, a virtual multi-channel transmission mechanism has been achieved. The network supports a maximum of 16 virtual channels for each physical data link. Time slots can be dynamically assigned to each virtual channel. Zero wait time has been achieved for the switching between different virtual channels.

关键词： communication protocol scalable optical ring hardware routing virtual multi-channel transmission time slot

Metallic photonic crystals for terahertz tunable filters

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Science china(information Sciences) 2012年第1期55卷 72-78页

作者： FAN Fei,CHANG ShengJiang&HOU Yu Institute of Modern Optics,Nankai University,key laboratory of Optical information Science and technology,ministry of education,tianjin 300071,china Institute of Modern Optics Nankai University Key Laboratory of Optical Information Science and Technology Ministry of Education Tianjin China

We have investigated the photonic band gap and transmission properties of metallic photonic crystals(PCs)filled with liquid crystal(LC)in the terahertz region by using the finite element method and the finite-dierence time-domain *** calculations on the LC-filled metallic PC and metallic PC waveguide demonstrated that they can realize low-loss broadband terahertz tunable filters,which have a tunable range of about 110 GHz and extinction ratio larger than 35 ***,the 3 dB bandwidths of the filters keep *** designed filters based on the metallic PC can greatly improve the performances in terms of loss,bandwidth and tunable region compared to those based on the LC-filled dielectric PC.

关键词： terahertz metallic photonic crystals liquid crystals filter

Influence of p-layer on the performance of n-i-p μc-Si:H thin film solar cells

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Science china(Physics,Mechanics & Astronomy) 2010年第11期53卷 2042-2046页

作者： YUAN YuJie 1,2,ZHANG KaiLiang 1,2,WEI Zhen 1,2 & GENG XinHua 3 1 College of electronics information Engineering,tianjin University of technology,tianjin 300384,china 2 tianjin key laboratory of Film Electronic and Communication Devices,tianjin University of technology,tianjin 300384,china 3 Institute of Photo-electronics Thin Film Devices and Technique,Nankai University,tianjin 300071,china College of electronics information Engineering Tianjin University of Technology Tianjin China tianjin key laboratory of Film Electronic and Communication Devices Tianjin University of Technology Tianjin China Institute of Photo-electronics Thin Film Devices and Technique Nankai University Tianjin China

The high pressure radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) process was adopted to prepare the n-i-p microcrystalline silicon solar cells,the influence of p-type layers on the performance of the solar cells was investigated,and the optimum p layer suited to the n-i-p microcrystalline silicon solar cells was *** experimental results demonstrate that the performance of the solar cells can be highly affected by the structural and optical properties of the p-layers,and the performance of solar cells can be greatly improved by optimizing p *** have achieved an initial active-area efficiency of 8.17% (V oc =0.49 V,J sc =24.9 mA/cm 2 ,FF=67%) for the μc-Si:H single-junction n-i-p solar cells and an initial active-area efficiency of 10.93% (V oc =1.31 V,J sc =13.09 mA/cm 2 ,FF=64%) for the a-Si:H/μc-Si:H tandem n-i-p solar cells.

关键词： microcrystalline silicon solar cells quantum confinement effect p-type layers

Design and experiment of electronic speckle shearing phase-shifting pattern interferometer

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optoelectronics Letters 2008年第1期4卷 59-61页

作者： XU Tian-hua, JING Chao, JING Wen-cai, ZHANG Hong-xia, JIA Da-gong, and ZHANG Yi-mo College of Precision Instrument & optoelectronics Engineering, National education ministry key laboratory of opto- electronics information and Technical Science, tianjin University, tianjin 300072, china College of Precision Instrument & optoelectronics Engineering National Education ministry Key Laboratory of Optoelectronics Information and Technical Science Tianjin University Tianjin China

An electronic speckle shearing phase-shifting pattern interferometer (ESSPPI) based on Michelson interferometer was based in this paper. A rotatable mirror driven by a step motor in one of its reflective arm is used to generate an adjustable shearing and the mirror driven by piezoelectric transducer (PZT) in the other reflective arm was used to realize phase- shifting. In the experiments, the deformation of an aluminum plate with the same extern-force on different positions and different forces on the same position is measured. Meanwhile, the phase distribution and phase-unwrap image of the aluminum plate with the extern-force on its center position is obtained by the four-step phase-shifting method.

关键词：电子相移模式干涉仪设计实验研究迈克逊干涉计

A fast algorithm for color image enhancement with total variation regularization

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Science china(information Sciences) 2010年第9期53卷 1913-1916页

作者： LI Ming1,2 1School of Computer Science and technology,Huazhong University of Science and technology,Wuhan 430074,china 2key laboratory of education ministry for Image Processing and Intelligent Control,Wuhan 430074,china School of Computer Science and technology Huazhong University of Science and Technology Wuhan China key laboratory of education ministry for Image Processing and Intelligent Control Wuhan China

In this paper,a novel algorithm for color image enhancement is *** proposed method,which is based on Retinex theory and total variational framework,improves the original variational method by using a TV penalty term to force spatial smoothness on the reflectance *** split Bregman algorithm is employed to solve the proposed *** practical experiments,it is verified that our method obtains better enhancement performance and much better calculation efficiency.

关键词： color image enhancement Retinex theory total variational model split Bregman algorithm

Effect of Sn^(4+) B-Site Substitution on the Microstructure and Dielectric Properties of Ba(Mg_(1/3)Ta_(2/3))O_3 Microwave Ceramics

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Journal of Materials Science & technology 2005年第5期21卷 773-775页

作者： Shunhua WU Guoqing WANG, Shuang WANG and Dandan LIUInstitute of electronics and information Engineering, tianjin University, tianjin 300072, china Institute of electronics and information Engineering Tianjin University Tianjin 300072 China

The effect of Sn^4＋（BaSnO3） B-site substitution on the microstructure and dielectric properties of Ba（Mg1/3Ta2/3）O3 microwave ceramics was investigated. X-ray diffraction shows that a complex perovskite material Ba（Mg1/3Ta2/3）O3 was prepared. As Sn^4＋ content x increases in the （1-x） Ba（Mg1/3Ta2/3）O3-xBaSnO3 （x=0.00～0.20） system, the dielectric constant generally keeps unchanged, while TCF changes from positive to negative. Although the addition of Sn^4＋ reduces the ordering degree, Q f0 is still increased when the ceramics density increases. This trend implies that Q f0 of this system is mostly determined by ceramics density rather than ordering degree. After sintering at 1500℃ for 3 h, the system with x=0.15 was found to have excellent dielectric properties as follows：ε≈25, Q f0≥300,000 GHz at 7 GHz, TCF=-0.6×10^-6/℃.

关键词： Ba(Mg1/3Ta2/3)O3 Complex perovskite Microwave Dielectric properties