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Graded doped structure fabricated by vacuum spray method to improve the luminance of polymer light-emitting diodes

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Nano-Micro Letters 2009年第1期1卷 19-22页

作者： X.Mo T.Mizokuro C.Heck N.Tanigaki T.Hiraga Materials Science Department Fudan University Photonics Research Institute National Institute of Advanced Industrial Science and Technology

An increase in luminance of a polymer light-emitting diode(PLED) was obtained by fabricating a graded doping structure using a vacuum spray method. The small electron transport molecule, Tris(8-hydroxyquinolinato) aluminum(III)(Alq3), was graded dispersed along the film in the direction of growth in the hole transport polymer poly(3-hexylthiophene-2,5-diyl)(P3HT, regiorandom) layer of the PLED, despite being dissolved in the same organic solvent as the polymer. The PLED reported here, which is composed of a graded structure, emitted brighter light than PLEDs composed of pure polymer or of a blend of active layers prepared by spin coating and/or vacuum spray methods.

关键词： Polymer light-emitting diodes luminance Graded doped Vacuum spray

Calibration of Imaging luminance Measuring Devices(ILMD)

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Calibration of Imaging Luminance Measuring Devices(ILMD)

Survey of visual just noticeable difference estimation

国防光电子论坛第二届新型探测技术及其应用研讨会

作者： Liying Liu Feng Zheng Lingxi Zhu Ye Li Kewei Huan Xiaoguang Shi Faculty of Science Changchun University of Science and Technology

A method of calibration of imaging luminance measuring devices has been studied. By the device-independent color space transformation, the color image by digital camera could be converted to the CIE’s absolute color space Lab. Then,the calibration model is fitted between ln(L/t) and luminance. At last, luminance image is obtained and the dynamic range of luminance image could be adjusted by shutter speed.

关键词： luminance Calibration Color image Absolute color space

来源： cnki会议评论

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Frontiers of Computer Science 2019年第1期13卷 4-15页

作者： Jinjian WU Guangming SHI Weisi LIN School of Electronic Engineering Xidian UniversityXi'an 710071China Collaborative Innovation Center of Information Sensing and Understanding Xidian UniversityXi'an 710071China School of Computer Engineering Nanyang Technological UniversitySingapore 639798Singapore

The concept of just noticeable difference (JND), which accounts for the visibility threshold (visual redundancy)of the human visual system,is useful in perceptionoriented signal processing *** this work,we present a comprehensive review of JND estimation ***, the visual mechanism and its corresponding computational modules are *** include luminance adaptation, contrast masking,pattern masking,and the contrast sensitivity ***,the existing pixel domain and subband domain YND models are presented and ***,the challenges associated with JND estimation are discussed.

关键词： just noticeable difference human visual system luminance adaptation contrast masking pattern masking contrast sensitivity function

Study of heat transfer characteristics in PCFG fabrication technology using heat method

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Chinese Optics Letters 2011年第2期9卷 18-22页

作者：齐跃峰乔汉平毕卫红 Institute of Information Science and Engineering Yanshan University

The fiber gratings fabrication technology with the heating method in a photonic crystal fiber （PCF） based on structural change is examined. The principle of photonic crystal fiber gratings （PCFGs） is analyzed in theory. The heat transfer theory and finite element method are used to examine the thermal field distribution in the fiber and the influence of the air hole structure in the cladding, and the parameters of the laser beam in the process of grating fabrication are discussed. The results show that gratings can be formed by the periodic collapse of air holes in the cladding of PCFs. Under double-point heating condition, the energy is uniformly distributed in the radial direction and is approximate to Gaussian distribution in the axial direction. With the same size of the luminous spot, as the layers and radius of the air holes increase, the laser power needed to make the air holes collapse decreases. With the same laser power, as the luminous spot radius increases, the needed heating time increases. Moreover, the relationship between the laser power needed and the air filling rate is obtained as the number of layers of the air holes changes from 1 to 7. This kind of PCFG can overcome the long-term thermal instability of conventional gratings in substance and thus has great potential applications in the related field of optical fiber sensors.

关键词： Crystal whiskers Fibers Finite element method Heating Laser theory luminance Nonlinear optics Optical fiber fabrication Optical fibers Photonic crystals

Enhanced Brightness of Eu^3＋ Complex in Organinc Electroluminescent Devices by Using Another Rare—Earth Ion

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Chinese Physics Letters 2002年第12期19卷 1884-1886页

作者：白峰李勇等 InstituteofOptoelectronicsTechnology LaboratoryofMaterialsforInformationStorageandDisplayMinistryofRailwayKeyLaboratoryNorthernJiantongUniversityBeijing100044 CollegeofChemistry

Rare-earth ions Tb3+ and La3+ were used as a bridge to improve the energy transfer from the polymer to an Eu complex. The material Tb(La)0.5Eu0.5(BSA)3phen was synthesized and used as the emission layer in the device: ITO/PVK:Tb(La)0.5Eu0.5(BSA)3phen/Alq/Al. The two device were compared in detail and it was found that the device using La0.5Eu0.5(BSA)3phen as the emission material had better monochromatic characteristics with the maximal brightness of 102cd/m2 and the colour coordinates x = 0.55 and y = 0.36.

关键词： luminance

Method for changing brightness temperature into true temperature based on twice recognition method

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Chinese Optics Letters 2007年第8期5卷 457-459页

作者：宋扬孙晓刚唐红 Department of Automation Measurement and Control Harbin Institute of Technology

The channel output of a multi-wavelength pyrometer is the brightness temperature rather than the true temperature. Twice recognition method is put forward to change the brightness temperatures of a multiwavelength pyrometer into the true temperatures of targets. Using the data offered by Dr. F. Righini, the experimental results show that the difference between the calculated true temperature based on twice recognition method and the real true temperature is within ±20 K. The method presented in this paper is feasible and effective for the true temperature measurement of targets.

关键词： Calculations luminance Pyrometers

Improvement of Efficiency and Brightness of Red Organic Light－Emitting Devices Using Double－Quantum－Well Configuration

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Chinese Physics Letters 2004年第3期21卷 556-558页

作者：米锐程刚赵毅谢文法候晶莹丁涛刘式墉 NationalLaboratoryofIntegratedOpticalElectronics JilinUniversityChangchun130023 DepartmentofMaterialsScience JilinUniversityChangchun130023

We present red double-quantum-well organic light-emitting devices (DQW-OLEDs), in which N,N-bis-(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyo-4,4'-diamine (NPB) is used as potential barriers and hole transport layer, 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-thtramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) doped tris (8-hydroxyquinoline) aluminium (Alq3) as potential wells and emitter, undoped Alq3 as electron transport layer, respectively. The turn-on voltage is about 4V. The maximum brightness and electroluminescent (EL) efficiency of the DQW device can reach 5916cd m−2 at 16V and 2.85cd A−1 at 7V, respectively. In addition, the EL efficiency of the DQW device is relatively independent of the drive voltage in the range from 5V to 16V.

关键词： luminance

Dependence of X—Ray Luminosity on Temperature for Groups and Clusters with the Moving Median Statistics

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Chinese Physics Letters 2002年第2期19卷 286-288页

作者：陈黎 DepartmentofAstronomy BeijingNormalUniversityBeijing100875

We re-analyse the relationship between the x-ray luminosity (LX) and the temperature (T) of groups and clusters of galaxies, based on the largest sample of 40 groups and 188 clusters. We employ the moving median statistics for the data set, along with the proper linear regression. Our newly established LX-T relations for groups and clusters show no significant difference within statistical uncertainties, yielding LX ∝ T 2.79±0.01 (groups) and LX ∝ T 2.54±0.004 (clusters). This also supports the hierarchical scenario of structure formation in which groups are simply the scale-down version of clusters. It is argued that the break in the LX-T relation on group scales detected in previous studies may suffer from sparse data sample and poor statistical methods.

关键词： luminance

No-Reference Image Quality Assessment Method Based on Visual Parameters

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Journal of Electronic Science and Technology 2019年第2期17卷 171-184页

作者： Yu-Hong Liu Kai-Fu Yang Hong-Mei Yan Key Laboratory for Neuroinformation of Ministry of Education University of Electronic Science and Technology of China Chengdu 610054 China Department of Biomedical Engineering Chengdu Medical College Chengdu 610050 China

Recent studies on no-reference image quality assessment (NR-IQA) methods usually learn to evaluate the image quality by regressing from human subjective scores of the training samples. This study presented an NR-IQA method based on the basic image visual parameters without using human scored image databases in learning. We demonstrated that these features comprised the most basic characteristics for constructing an image and influencing the visual quality of an image. In this paper, the definitions, computational method, and relationships among these visual metrics were described. We subsequently proposed a no-reference assessment function, which was referred to as a visual parameter measurement index (VPMI), based on the integration of these visual metrics to assess image quality. It is established that the maximum of VPMI corresponds to the best quality of the color image. We verified this method using the popular assessment database—image quality assessment database (LIVE), and the results indicated that the proposed method matched better with the subjective assessment of human vision. Compared with other image quality assessment models, it is highly competitive. VPMI has low computational complexity, which makes it promising to implement in real-time image assessment systems.

关键词： Bandwidth human visual system information entropy luminance no-reference image quality assessment (NR-IQA) visual parameter measurement index (VPMI)