最新刊期
期 6 ， 2011
- 摘要：The phase transitions of molecular system consisted by double rectangular plates connected by flexible chain are studied in this paper. Based on a simple interaction energy between molecules and the approximation of mean-field theory, as the interaction strength of flexible chain increases, four kinds of phase diagrams in the plane of molecular structure and temperature are obtained. In the first kind (where the interaction strength is the smallest) there is only one Landau point that allows system directly transit from isotropic phase to biaxial phase. In the second kind, Landau point spreads to a Landau curve. The region of positive uniaxial phase increases and that of negative uniaxial phase decreases. In the phase diagram, a first order transition from uniaxial phase to biaxial phase appears. In the third kind Landau point also spreads to a Landau curve, but the region of negative uniaxial phase disappears. In the fourth kind(the interaction strength of flexible chain is the largest), the range of Landau curve becomes narrower.关键词：biaxial nematics;phase transition;tetrapodes
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发布时间：2020-08-12 - 摘要：The bent-core nematic liquid crystals discovered in recent years is a new kind of liquid crystals with special electro-optical property. The molecules have the unique bent shape, performing great characteristics which are different from rod-like liquid crystals. However, these molecules with bent-core nematic commonly have high melting point and wide temperature range of smetic phases. This paper overviews the current state of research in the field of bent-core nematic liquid crystals of molecular structures, properties and the research situation of bent-core molecules with nematic phases based on the substituted resorcinol, naphthalene, oxadiazole etc as the central units and ester group, C=N (N=N) etc as the bridge bonds, and the influence of lateral substitution on the liquid crystal behavior was given.关键词：bent-core;nematic phases;liquid crystal
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发布时间：2020-08-12
Material Physics & Chemistry
- 摘要：As a proton acceptor, rod-like isonicotinic acid derivatives could form hydrogen bonds with symmetrical disc-like core phloroglucinol and obtain a supramolecular discotic liquid crystal structure. Temperature dependent FT-IR was used to study the thermal stability of the complexes at the aid of DSC and POM, and the phase structures were confirmed by using X-ray diffraction technique. The results show that the ester-linked bond can reduce the order degree of H-bonded system and induce discotic nematic liquid crystals.关键词：supramolecule;hydrogen bond;isonicotinic acid derivatives;discotic liquid crystal;discotic nematic
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发布时间：2020-08-12 - 摘要：Image-retention phenomenon which exists in different kinds of LCDs is mostly caused by ionic charge effect. This thesis focuses on free ionic charge adsorption of alignment layer and free ionic charge density of different liquid crystal materials. We can further eliminate image-retention phenomenon by choosing appropriate materials. The experimental results indicate that with appropriate alignment layer. the more time of realignment the easier to avoid image-retention phenomenon. With certain alignment layer,it's easier to avoid image-retention phenomenon when choosing liquid crystal at low threshold voltage or with anlistatig. However,in practical application,the increasing realignment time will have a bad effect on liquid crystal steep and response time, and it's easier to make LCDs display unevenly. In conclusion,only by balancing all the conditions above it can improve Image-Retention Phenomenon more effectively,and increase displaying quality of STN-LCD.关键词：STN-LCD;image retention display;ionic charge effect
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发布时间：2020-08-12 - 摘要：E-paper market has great potential and huge development in the next three years. The advantages and drawbacks of the current flexible display technology nowadays were described. Cholesteric liquid crystal display technology has great advantage on consumption, colorization, contrast, aseismicity, etc. but the high cost will be a bottleneck for the further development and popularization. The advanced technologies and industrialization of cholesteric liquid crystal display technology were mainly controlled by the developed countries. The Chinese universities and research institutions still work on the primary studies. Fudan University's research findings on the cholesteric liquid crystal display was described in this paper. Combining the characteristics of flexible display industry and the industrial environment in China, three suggestions were proposed.关键词：cholesteric liquid crystal;flexible display;technology;industry;development proposal
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发布时间：2020-08-12 - 摘要：Using the self-built test platform, the influence of the temperature on the transmission spectra of the Thin-Film-Transistor Liquid Crystal Display (TFT-LCD) in visible wavelength is investigated. The results show that the transmissivities of the red, green and blue light first increase and then decrease with the increasing temperature, but the peaks present at different temperatures. The reason is that the refractive index is changed with temperature change, and the scattering is also changed because the director of liquid crystal molecules has fluctuation. Therefore, the transmissivity of tricolor is changed.关键词：liquid crystal;TFT-LCD;tricolor;transmissivity;temperature characteristics
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发布时间：2020-08-12 - 摘要：In order to meet the big screen display's requirements on touchpad and overcome the disadvantages of interactive touchpad on property and cost, a new type of touchpad technology was invented which was an application of optical system imaging principle as well as optical sensing device of PSD. The infrared spotlight source of contact point of touch pen and touch board imaging on the optical sensor through simple optical system consisted of optical lens and the location of the touch point will be determined by data processing such as coordinates correction. The low cost, easy integration, high sensitivity, high speed of data processing and simple system structure of the new touchpad can be applied to the big size and proportion of the touchpad.关键词：touch technology;imaging systems;image processing;touch information;sensor
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发布时间：2020-08-12 - 摘要：In order to improve the uniformity of the LCD backlight, a kind of plano-concave lens array was used in straight down type LCD backlight module instead of the diffusion films. For 106.68 mm (42 in) LCD monitor LED backlight, the illuminance distribution was simulated, and the optimized lens radius,structure, distance of LED array were determined. The effect of different lens radius and lens array position on the uniformity of backlight was also discussed. The results show that the plano-concave lens array can diffuses lights better when the radius of lens is 1 mm and the thickness of lens is 2 mm, the uniformity of light reaches 88.61%.关键词：backlight module;LED array;uniformity
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发布时间：2020-08-12 - 摘要：The relation of color fringing field with the pixel size and thickness of color filters was researched in this paper, and the study was based on the three-dimensional (3D) optical modeling we established before. These two parameters may affect the color, reflectivity, contrast, and other properties of the CF-LCoS microdisplays. The optimization of pixel size and thickness of color filters should be compromised among these display properties for specific applications.关键词：color filter;LCoS;microdisplay;three-dimensional;optical modeling;optimization
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发布时间：2020-08-12
Device Technology & Physics
- 摘要：To satisfy the requirement of graphic and text display of instrument, a hardware and software design of a LED Dot-matrix Display was introduced. The display used LED Dot-matrix as its display device, and ARM core microcontroller as its control device. Detail descriptions to the working principle, hardware structure, and programming technique were provided. Schematics for the hardware design were also explained.关键词：instruments;LED dot-matrix display;LPC2368;serial communication
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发布时间：2020-08-12 - 摘要：A LCD display system of the embedded Neighborhood Image Parallel Computer (NIPC-3e) is presented in this paper. This system can display either original or images which have been processed by the Neighborhood Image Parallel Computer. A LCD display controller based on FPGA, SRAM, CPLD and SDRAM is proposed. This paper further introduced the detail design of the three major components of this display controller: the interface between CPLD and NIPC-3e, the timing drive of LCD based on CPLD and the timing control logic of SDRAM based on CPLD. This display system has been successfully implemented and applied to NIPC-3e based applications including face detection and gesture recognition.关键词：neighborbord image parallel computer;CPLD;SDRAM;LCD display
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发布时间：2020-08-12 - 摘要：A white field apparatus was developed, with which the standardization of instruments for color measurement could be finished. The apparatus system was based on LCD and was realized with FPGA. By recording and reproducing the calibration information, the white field apparatus could provide white field with standard color temperature. The FPGA controller board, the SVGA signal driver for LCD and NOR Flash ROM driver were designed and realized for the hardware and software system. As tested, the white field apparatus could provide standard white fields with adjustable color temperature after calibration by metrology institutes and operated steadily and reliably with the luminance error of 0.50% within 24 h.关键词：LCD;standard white field;FPGA;parallel NOR Flash;SVGA driving
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发布时间：2020-08-12 - 摘要：Aiming to the current market demand for two-way video monitoring system, dual remote video monitoring system based on FPGA and ARM11 was designed and implemented. The system can receives two CVBS signals by two SAA7111A decoder chips. Under the control of the FPGA, the two-way signal was synthesized to one way and transmitted to the ARM11 module. ARM11 module can compress a received video stream into packages and send to the IP Internet. The client can obtain two-way monitor screen through the network connection. The test shows that the system can achieve a stable two-way video signal playback and meet the design requirements of video products.关键词：ARM;FPGA;video capture;ITU-R BT.656;SAA7111A
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发布时间：2020-08-12 - 摘要：A simple but efficient Chinese characters display programming method aiming at dot matrix liquid crystal display was provided and illustrated in detail with Keil C language which was widely used currently. This method would decrease hardware cost, make programming more easily, and make it conceivable to simulate running of intelligent instruments with Proteus software. This method could be applied to all kind of dot matrix liquid crystal display.关键词：liquid crystal display;Chinese characters display;intelligent instruments
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发布时间：2020-08-12 - 摘要：An encoder debugging system based on C8051F340 and Labview was designed in the paper. The design realizes multi-signal sampling of encoder with the AD module embedded in C8051F340, and USB communication with PC using the USB module embedded in C8051F340. PC application was programmed employing Labview, and the angle was displayed by two methods, one of which is light emission displaying and the other was "degrees, minutes and seconds" displaying. Meanwhile, the signal waveform was displayed by Lissajous graphics and oscillographs. The result showed that the system speed is higher with the feature of easier operation, and the application surface was friendly with rich information. And then the system functions can be expanded.关键词：encoder;display;C8051F340;Labview;USB
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发布时间：2020-08-12 - 摘要：Based on dual-color screen with 12 interfaces as an example, the unit circuit configu- ration of LED bar display panel was described. On this basis, the data organization of LED bar display panel was in-depth discussed when the data was horizontally shifting in the manner of shoot-through connection. In this paper, a display round was designed to lively demonstrate the data organization and its storage. In this way, only after the memory address plus one, the display data can be quickly output.关键词：LED bar display panel;data organization;display round
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发布时间：2020-08-12 - 摘要：A single chip Mobile Display Digital Interface (MDDI) data processing chip was developed for AM-OLED (Active Matrix Organic Light-Emitting Diode) display screen. MDDI is widely used in the mobile display area because of its low-power, small-area and high signal transmission reliability. The design of chip supports 240 RGB×320 Dot, 260k-color image data, and the refreshing rate of the display screen is 40~60 Hz. Because large amount of input data and the MDDI only support serial data, the working frequency of the circuit can achieve 100 MHz. So this design take all limit factors into consideration, such as the chip area, working frequency and power consumption. FPGA verification illustrates that the design accords with the specification.关键词：MDDI;AM-OLED;display control;CMOS
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发布时间：2020-08-12 - 摘要：DAC and drive Buffer is a key module of TFT-LCD source driver IC, which determines the main properties of the chip. Firstly, the drawbacks of traditional R-DAC structure used for 10-bit TFT-LCD source driver circuit was discussed, then the new R-DAC + C-DAC principles and design methods were described. The proposed DAC circuit was designed and realized using 0.35 μm 5 V CMOS process. The results of Hspice simulation show that the DNL and INL of DAC circuit are less than 0.4 LSB or 1.5 LSB, respectively, and the output voltage settling time is less than 3.5 μs. The chip area of new structure DAC is 1/8 of the traditional structure DAC, and can achieve the 10 billion colors (210×210×210) display.关键词：TFT-LCD;source driver IC;DAC;true color display
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发布时间：2020-08-12 - 摘要：The display system for a portable detecting instrument was designed based on TMS320LF2407 DSP and 1/4VGA LCM . The design scheme of the hardware interface between DSP and LCM was presented, and the control software was programmed using C language which resolved the timing match problem between DSP and LCM. With good implementation, the control program can be used easily in other display system consisted by DSP and LCM.关键词：DSP;LCD;C language;interface
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发布时间：2020-08-12
Driving & Controlling
- 摘要：The high noise of ESPI(Electronic Speckle Pattern Interferometry) fringe pattern leads to the low ratio of signal-to-noise, there are some drawbacks of common image filtering method used in the speckle interferometry fringe pattern. According to the characteristics of speckle fringe pattern, the iterative filtering method based on adaptive filter and wavelet transform was established. On the basis of speckle fringe image pretreatment, the different wavelet functions, decomposition levels and threshold were chosen to achieve the different filtering effect. The repeated experiments proved that the iterative filter effect is the best when the threshold is 0.15~0.3 and wavelet function with the 4 layer decomposition, and then the image binarization and edge detection was carried out using Sobel operator, finally the marginal distribution of ESPI fringe pattern was obtained. The experiment results indicate that the method is able to achieve a good effect in the respect of speckle noise removal and edge preservation during the process.关键词：ESPI pattern;wavelet filter;iterative filter;edge extraction
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发布时间：2020-08-12 - 摘要：The scene generation technology based on algorithm of image resolution enhancement, aiming at the needs of high image resolution and zooming browse in virtual environment was studied. The algorithm of image resolution enhancement contains two situations. First, for one frame, a novel image zooming algorithm based on maximum a posteriori probability and maximum entropy principle was presented, which anisotropy interpolate pixels using gradient information self-adaptively. Second, in the case of multi-frames,super-resolution reconstruction algorithm based on generalized MAP theory and maximum entropy principle was presented. By introducing bifilter into traditional MAP algorithm,we anisotropy interpolate pixels using gradient information and geometry distance self-adaptively. Experimental results show that our algorithm holds higher signal/noise ratio and better vision quality.关键词：high image resolution;one frame image;multi-frames;bilateral filtering;signal noise ratio
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发布时间：2020-08-12 - 摘要：The moving objectives detecting technology in video surveillance system was stu-died. On the base of analysis and comparison of several target detection algorithm, a way of using block processing method to establish the initial background model was proposed. The method had a good inhibitory effect on the noise in video sequences, and it can overcome the shortcomings of fuzzy and residual shadow caused by mean method; In order to meet the change of background, the three-frames differences method was used to find those pixels that had a significant difference, then these pixels were updated adaptively. Simulation experiment showed that, this method can be used in background subtraction algorithm. The moving targets can be detected rapidly, completely and accurately.关键词：moving objectives detecting;background modeling;background updating;background subtraction
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发布时间：2020-08-12 - 摘要：New method, back propagation neural network based face recognition was presented in this paper. The proposed method extracts feature from face image with differential projection and geometrical features into eigenvector which was classified by back propagation neural network. The experimental results on ORL face database show that the proposed method can achieve an average recognition accuracy of 99% by using only 13 features. Moreover, the identified power was enhanced effectively, and the computing complexity and feature dimensions were reduced greatly.关键词：face recognition;back propagation neural network;image eigenvector
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发布时间：2020-08-12 - 摘要：The image resolution can be improved without increasing the requirement of optical imaging systems's parameters or decreasing the size of CCD pixel by staggered arrays technology,which arranges several CCDs in a specific mode.In this paper, an image super resolution method of improving the image resolution for 1.5 times both in two directions by 4 linear arrays staggered based on this technology was presented, which avoids the large computation in a single time by using circulation method. This method is proved effectively by the digital simulation, and a simulated experiment platform was constructed to test its feasibility. The image resolution is improved about 1.42 times of the unreconstructed image according to the imaging experiment of resolution chart, which is closed to 1.5 times in ideal case. Also, the reconstructed and unreconstructed images was evaluated by the image information entropy, which proves that the reconstructed image contains more information.关键词：CCD sampling;staggered arrays;super resolution
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发布时间：2020-08-12 - 摘要：SPIHT and NLS (Not List SPIHT) are efficient image compression algorithms, but the algorithms application is limited by the shortcomings of the poor error resistance and slow compression speed in the aviation areas. In this paper, the error resilience and the compression speed were improved. The remote sensing images were decomposed by Le Gall5/3 wavelet, and wavelet coefficients were indexed, scanned and allocated by the means of family blocks. The bit-plane importance was predicted by bitwise OR, so the N bit-planes can be encoded at the same time. Compared with the SPIHT algorithm, this modified algorithm is easy implemented by hardware. The experiments results show that the PSNR of reconstructed images was increased about 0.2 to 0.6 db and the speed was 4~6 times faster than the SPIHT encoding process. The speed can be further improved via virtue of the parallelism and pipelining, when it is implemented by the hardware.关键词：aerial applications;high-speed SPIHT;error resistance;bit-plane parallel
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发布时间：2020-08-12 - 摘要：To improve the dynamic and static image quality, a new adaptive limited grays subfield coding method based on histogram equalization was proposed. In this method, a new probability density distribution was obtained by image histogram equalization. The gray scales were divided uniformity according to the number of subfield, and the grays in middle of each sub-section as the pre-sample grays were selected. The sample grays and subfield coding were obtained through the inverse transformation of histogram equalization. A subfield was set to zero for one gray coding to get the better image quality. Simulation results show that the proposed method has the advantages of simple-accumulation and combination lighting modes. It can improve the dynamic false contrast and gray scales expression simultaneously.关键词：plasma display panel;histogram equalization;limited grays subfield coding
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发布时间：2020-08-12 - 摘要：A high accuracy sub-pixel-level motion estimation of algorithm based on phase-only correlation was proposed.This algorithm consists of two steps: one for pixel-level correspondence estimation and the other for sub-pixel-level correspondence estimation. In pixel-level estimation, the method of image subtract or method of template matching are used to find the target image in the original input images for two classes of motion, namely local motion and global motion, then the pixel-level image shift enables to be detected coarsely by calculating the coordinate of center of the target image. In sub-pixel-level estimation, the method of image registration based on phase-only correlation(POC) is employed to detect sub-pixel-level displacement, which applies the translation characteristics of Fourier transform to search translation between images. The 2-D inverse Fourier transform for the normalized cross spectrum is a 2-D impulse function, the impulse enables to determine the translation displacement from the location of the correlation peak, so as to obtain finely image displacement. The method described in this paper has been applied to the experimental of registration of light-spot from autocollimator. The result shows that this method can detect sub-pixel- level shift parameters accurately and efficiently,which makes possible to estimate the displacement with 0.1-pixel accuracy, the maximum error of registration is only 0.156-pixel,and the root of mean square error of image registration is better than 0.091-pixel.关键词：phase-only correlation;sub-pixel-level;image registration;motion estimation
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发布时间：2020-08-12
Imaging Technology & Image Processing
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