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Repeatability,interocular correlation and agreement of optic nerve head vessel density in healthy eyes:a sweptsource optical coherence tomographic angiography study
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作者 Dan-Qi Fang Da-Wei Yang +2 位作者 Xiao-Ting Mai Carol Y Cheung Hao-Yu Chen 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2024年第5期896-903,共8页
AIM:To assess the repeatability,interocular correlation,and agreement of quantitative swept-source optical coherence tomography angiography(OCTA)optic nerve head(ONH)parameters in healthy subjects.METHODS:Thir ty-thre... AIM:To assess the repeatability,interocular correlation,and agreement of quantitative swept-source optical coherence tomography angiography(OCTA)optic nerve head(ONH)parameters in healthy subjects.METHODS:Thir ty-three healthy subjects were enrolled.The ONH of both eyes were imaged four times by a swept-source-OCTA using a 3 mm×3 mm scanning protocol.Images of the radial peripapillary capillary were analyzed by a customized Matlab program,and the vessel density,fractal dimension,and vessel diameter index were measured.The repeatability of the four scans was determined by the intraclass correlation coefficient(ICC).The most well-centered optic disc from the four repeated scans was then selected for the interocular correlation and agreement analysis using the Pearson correlation coefficient,ICC and Bland-Altman plots.RESULTS:All swept-source-OCTA ONH parameters exhibited certain repeatability,with ICC>0.760 and coefficient of variation(CoV)≤7.301%.The obvious interocular correlation was observed for papillary vessel density(ICC=0.857),vessel diameter index(ICC=0.857)and fractal dimension(ICC=0.906),while circumpapillary vessel density exhibited moderate interocular correlation(ICC=0.687).Bland-Altman plots revealed an agreement range of-5.26%to 6.21%for circumpapillary vessel density.CONCLUSION:OCTA ONH parameters demonstrate good repeatability in healthy subjects.The interocular correlations of papillary vessel density,fractal dimension and vessel diameter index are high,but the correlation for circumpapillary vessel density is moderate. 展开更多
关键词 interocular correlation REPEATABILITY optic nerve head optical coherence tomography angiography vessel density
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Mathematical demonstration of correlation of optical prime code 被引量:1
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作者 李传起 张明德 孙小菡 《Journal of Southeast University(English Edition)》 EI CAS 2006年第2期153-158,共6页
Starting from the configuration of the optical prime code, a kind of key signature code for the optical code-division multiple access (OCDMA) system, based on the linear congruence theory in the finite Galois field,... Starting from the configuration of the optical prime code, a kind of key signature code for the optical code-division multiple access (OCDMA) system, based on the linear congruence theory in the finite Galois field, the correlation properties of the basic prime code, the extended prime code and the modified prime code are mathematically analyzed, the distribution of cross-correlation values is given and the overlap area of "1"s in the case of periodically circularly shifting is indicated. It is mathematically demonstrated that the maximum cross-correlation of the basic prime code is 2, and that of the extended prime code and the modified prime code is 1. The integrated correlation analysis process is proposed. The signal-interfere ratio (SIR) and the BER performance of the systems employing different signature codes are calculated, respectively, and the performances of OCDMA systems employing different signature codes mode are compared. 展开更多
关键词 fiber-optic communication optical code-division multiple access optical prime code correlation
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A novel indirect optical method for rock stress measurement using microdeformation field analysis
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作者 Yujie Feng Peng-Zhi Pan +2 位作者 Zhaofeng Wang Xufeng Liu Shuting Miao 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第9期3616-3628,共13页
Stress measurement plays a crucial role in geomechanics and rock engineering,especially for the design and construction of large-scale rock projects.This paper presents a novel method,based on the traditional stress r... Stress measurement plays a crucial role in geomechanics and rock engineering,especially for the design and construction of large-scale rock projects.This paper presents a novel method,based on the traditional stress relief approach,for indirectly measuring rock stress using optical techniques.The proposed method allows for the acquisition of full-field strain evolution on the borehole’s inner wall before and after disturbance,facilitating the determination of three-dimensional(3D)stress information at multiple points within a single borehole.The study focuses on presenting the method’s theoretical framework,laboratory validation results,and equipment design conception.The theoretical framework comprises three key components:the optical imaging method of the borehole wall,the digital image correlation(DIC)method,and the stress calculation procedure.Laboratory validation tests investigate strain field distribution on the borehole wall under varying stress conditions,with stress results derived from DIC strain data.Remarkably,the optical method demonstrates better measurement accuracy during the unloading stage compared to conventional strain gauge methods.At relatively high stress levels,the optical method demonstrates a relative error of less than 7%and an absolute error within 0.5 MPa.Furthermore,a comparative analysis between the optical method and the conventional contact resistance strain gauge method highlights the optical method’s enhanced accuracy and stability,particularly during the unloading stage.The proposed optical stress measurement device represents a pioneering effort in the application of DIC technology to rock engineering,highlighting its potential to advance stress measurement techniques in the field. 展开更多
关键词 Rock stress measurement optical technology Digital image correlation(DIC)technology Micro-deformation field
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A NEW DECODER OF SYNCHRONOUS OPTICAL CODE DIVISION MULTIPLE ACCESS SYSTEMS USING SEGMENTED CORRELATION
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作者 Li Ou Wu Jiangxing Lan Julong(National Digital Switching System Engineering & Technology Research Center, Zhengzhou 450002) 《Journal of Electronics(China)》 2001年第2期135-139,共5页
A new segmented correlating decoder of synchronous optical CDMA using modified prime sequence codes is proposed. The performance of the proposed system is analyzed under the assumption of Poisson shot noise model for ... A new segmented correlating decoder of synchronous optical CDMA using modified prime sequence codes is proposed. The performance of the proposed system is analyzed under the assumption of Poisson shot noise model for the receiver photodetector. The decoder technique is shown to be more effective to improve the bit error probability performance than the method using an optical hard-limiter. 展开更多
关键词 SYNCHRONOUS optical CDMA PRIME CODES Multiple access system SEGMENTED correlation
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Simulation of distributed optical fiber disturbance detection system based on Sagnac/Mach-Zehnder interferometer and cross-correlation location 被引量:2
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作者 方捻 李杰 +2 位作者 王陆唐 黄肇明 杨烨 《Journal of Shanghai University(English Edition)》 CAS 2011年第2期115-118,共4页
A distributed optical fiber disturbance detection system consisted of a Sagnac interferometer and a Mach-Zehnder interferometer is demonstrated. Two interferometers outputs are connected to an electric band-pass filte... A distributed optical fiber disturbance detection system consisted of a Sagnac interferometer and a Mach-Zehnder interferometer is demonstrated. Two interferometers outputs are connected to an electric band-pass filter via a detector respectively. The central frequencies of the two filters are selected adaptively according to the disturbance frequency. The disturbance frequency is obtained by either frequency spectrum of the two interferometers outputs. An alarm is given out only when the Sagnac interferometer output is changed. A disturbance position is determined by calculating a time difference with a cross-correlation method between the filter output connected to the Sagnac interferometer and derivative of the filter output connected to the Mach-Zehnder interferometer. The frequency spectrum, derivative and cross-correlation are obtained by a signal processing system. Theory analysis and simulation results are presented. They show that the system structure and location method are effective, accurate, and immune to environmental variations. 展开更多
关键词 Sagnac interferometer Mach-Zehnder interferometer distributed optical fiber disturbance detection system cross-correlation LOCATION
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Optical encryption scheme based on spread spectrum ghost imaging
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作者 刘进芬 董玥 +1 位作者 王乐 赵生妹 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第7期375-381,共7页
An optical encryption(OE) scheme based on the spread spectrum ghost imaging(SSGI), named as SSGI-OE, is proposed to obtain a high security with a smaller key. In the scheme, the randomly selected row number of a Hadam... An optical encryption(OE) scheme based on the spread spectrum ghost imaging(SSGI), named as SSGI-OE, is proposed to obtain a high security with a smaller key. In the scheme, the randomly selected row number of a Hadamard matrix of order N is used as the secure key, and shared with the authorized user, Bob, through a private channel. Each corresponding row vector of the order-N Hadamard matrix is then used as the direct sequence code to modulate a speckle pattern for the ghost imaging system, and an image is encrypted with the help of the SSGI. The measurement results from the bucket detector, named as ciphertext, are then transmitted to Bob through a public channel. The illuminating speckle patterns are also shared with Bob by the public channel. With the correct secure key, Bob could reconstruct the image with the aid of the SSGI system, whereas the unauthorized user, Eve, could not obtain any useful information of the encrypted image. The numerical simulations and experimental results show that the proposed scheme is feasible with a higher security and a smaller key. For the 32 × 32 pixels image, the number of bits sent from Alice to Bob by using SSGIOE(M = 1024, N = 2048) scheme is only 0.0107 times over a computational ghost imaging optical encryption scheme.When the eavesdropping ratio(ER) is less than 40%, the eavesdropper cannot acquire any information of the encrypted image. The extreme circumstance for the proposed SSGI-OE scheme is also discussed, where the eavesdropper begins to extract the information when ER is up to 15%. 展开更多
关键词 optical encryption ghost imaging spread spectrum correlated imaging
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Correlation between macular blood flow density and stage of diabetic retinopathy
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作者 DENG Yu JIE Chuan-hong +3 位作者 WANG Jian-wei SONG Xiao-hua LIU Zi-qiang LI Yuan-yuan 《Journal of Hainan Medical University》 2023年第3期36-41,共6页
Objective:To investigate the association between the development of diabetic retinopathy and OCTA blood flow density.Methods:A total of 63 patients(100 eyes)diagnosed with type 2 diabetes in Eye Hospital of China Acad... Objective:To investigate the association between the development of diabetic retinopathy and OCTA blood flow density.Methods:A total of 63 patients(100 eyes)diagnosed with type 2 diabetes in Eye Hospital of China Academy of Chinese Medical Sciences from September 2020 to July 2021 were selected,including 44 patients(72 eyes)with diabetic retinopathy and 19 patients(28 eyes)with type 2 diabetes without retinopathy(NDR).All patients underwent OCTA examination,and FAZ,PERIM,AI,FD,SVD,DVD and other indicators were counted.Results:(1)SVD,parafoveal SVD,DVD and parafoveal DVD gradually decreased with the progression of DR(P=0.000).There was no significant difference in SVD and DVD fovea(P>0.05).(2)The correlation coefficients between SVD,SVD,DVD,DVD and DR process were-0.525,-0.586,-0.323,-0.424,respectively(P<0.05),and all showed moderate negative correlation.(3)AI and FD gradually decreased with the progression of DR,and the differences were statistically significant(P=0.011,P=0.000),while FAZ and PERIM showed no significant difference with the progression of DR(P>0.05).(4)The correlation coefficients of FAZ,PERIM and DR progression were:-0.031,0.084(P>0.05),no correlation,AI,FD and DR process correlation coefficient were 0.307,-0.459(P<0.05),respectively,were moderately positive and negative correlation;(5)The correlation coefficients of FAZ,PERIM,AI,FD and age were-0.124,-0.052,0.113,-0.170(P>0.05),respectively.Conclusion:There is a moderate correlation between the progression of DR and the superficial and deep blood flow density of OCTA.It was moderately correlated with AI and FD.OCTA can assist in the assessment of DR disease progression. 展开更多
关键词 Diabetic retinopathy optical coherence tomography ANGIOGRAPHY Vessel density correlation analysis preface
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Investigating the Long-Term Relationship between Aerosol Optical Thickness and Land Use/Cover Change in Guangxi Coastal Cities, China
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作者 Shiheng Cheng Xuemei Zhong +2 位作者 Xiangling Tang Aofeng Wang Haili Long 《International Journal of Geosciences》 2023年第6期515-530,共16页
Land Use/Cover Change (LUCC) has an impact on AOD to a certain extent. It is of great significance for ecological environment and public health to pay attention to and explore the response mechanism of AOD to LUCC. Ba... Land Use/Cover Change (LUCC) has an impact on AOD to a certain extent. It is of great significance for ecological environment and public health to pay attention to and explore the response mechanism of AOD to LUCC. Based on remote sensing satellite technology, using landsat8 and MODIS data, this paper analyzes the correlation between different land use types and AOD in Beibu Gulf coastal urban belt under the background of wide-scale region and long time series, and further discusses the difference value and contribution level of each LUCC to AOD. The results show that: 1) there is a positive correlation between PM concentration and cultivated land, urban land, water area and other types of land, and the correlation coefficient increases in turn, R is 0.812, 0.685, 0.627, 0.416, respectively, which indicates that the increase of cultivated land and urban land increases PM concentration to a certain extent;2) there is a significant negative correlation between PM concentration and forest land, R is -0.924, The results show that the decrease of woodland is an important factor for the increase of atmospheric particulate matter concentration in the study area from 2015 to 2019;3) through the contribution analysis method, the contribution of cultivated land to AOD is the largest, followed by urban land, and the water area is the smallest in 2015-2019, which indicates that the land use mode is closely related to AOD. It can be helpful to reasonably plan land use types and scientifically optimize land use structure. It can effectively reduce the concentration of air pollution particles. 展开更多
关键词 Land Use and Land-Cover Change (LUCC) MODIS Aerosol optical Depth (AOD) correlation Analysis Contribution Analysis
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Features of aerosol optical depth and its relation to extreme temperatures in China during 1980–2001 被引量:6
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作者 HU Ting SUN Zhaobo LI Zhaoxin 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2011年第2期33-45,共13页
Based on Total Ozone Mapping Spectrometer (TOMS) monthly aerosol optical thickness (AOT) measurements in 1980–2001 a study is made of space/time patterns and difference between land and sea of AOT 0.50 μm thick ... Based on Total Ozone Mapping Spectrometer (TOMS) monthly aerosol optical thickness (AOT) measurements in 1980–2001 a study is made of space/time patterns and difference between land and sea of AOT 0.50 μm thick over China,which are put into correlation analysis with synchronous extreme temperature indices (warm/cold day and night).Results suggest that 1) the long-term mean AOT over China is characterized by typical geography,with pronounced land-sea contrast.And AOT has significant seasonality and its seasonal difference is diminished as a function of latitude.2) On the whole,the AOT displays an appreciably increasing trend,with the distinct increase in the eastern Qinghai-Tibetan plateau and SW China,North China,the mid-lower Changjiang (MiLY) valley as well as the South China Sea,but marginal decrease over western/northern Xinjiang and part of South China.3) The AOT over land and sea is marked by conspicuous intra-seasonal and -yearly oscillations,with remarkable periods at one-,two-yr and more (as interannual periods).4) Land AOT change is well correlated with extremely temperature indexes.Generally,the correlations of AOT to the extreme temperature indices are more significant in Eastern China with 110 ° E as the division.Their high-correlation regions are along the Southern China coastline,the Loess Plateau and the Sichuan Basin,and even higher in North China Plain and the mid-lower Changjiang River reaches.5) Simulations of LMDZ-regional model indicate that aerosol effects may result in cooling all over China,particularly in Eastern China.The contribution of aerosol change may result in more decrease in the maximum temperature than the minimum,with decrease of 0.11/0.08 K for zonal average,respectively. 展开更多
关键词 aerosol optical thickness extreme temperature index space/time pattern TREND correlation
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Theoretical analysis of stack gas emission velocity measurement by optical scintillation 被引量:1
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作者 杨阳 董凤忠 +4 位作者 倪志波 庞涛 曾宗泳 吴边 张志荣 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第4期202-207,共6页
Theoretical analysis for an online measurement of the stack gas flow velocity based on the optical scintillation method with a structure of two parallel optical paths is performed. The causes of optical scintillation ... Theoretical analysis for an online measurement of the stack gas flow velocity based on the optical scintillation method with a structure of two parallel optical paths is performed. The causes of optical scintillation in a stack are first introduced. Then, the principle of flow velocity measurement and its mathematical expression based on cross correlation of the optical scintillation are presented. The field test results show that the flow velocity measured by the proposed technique in this article is consistent with the value tested by the Pitot tube. It verifies the effectiveness of this method. Finally, by use of the structure function of logarithmic light intensity fluctuations, the theoretical explanation of optical scintillation spec- tral characteristic in low frequency is given. The analysis of the optical scintillation spectrum provides the basis for the measurement of the stack gas flow velocity and particle concentration simultaneously. 展开更多
关键词 optical scintillation cross correlation flow velocity SPECTRUM
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Structural-visual functional relationships detected by optical coherence tomography in varying age-cohorts' patients with optic neuritis 被引量:2
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作者 Wei Shi Hong-Tao Zhang +7 位作者 Hua-Xin Zuo Si-Yuan Li Pan-Pan Zheng Quan-Gang Xu Si-Yu Cai Shi-Hui Wei Li Li Chun—Xia Peng 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2022年第6期967-974,共8页
AIM: To assess the relationships of final best-corrected visual acuity(BCVA) and the optic nerve structural loss in varying age-cohorts of optic neuritis(ON) patients.METHODS: This is a retrospective, cross-sectional ... AIM: To assess the relationships of final best-corrected visual acuity(BCVA) and the optic nerve structural loss in varying age-cohorts of optic neuritis(ON) patients.METHODS: This is a retrospective, cross-sectional study.Totally 130 ON subjects(200 eyes) without ON onset within 6mo were included, who underwent BCVA assessment,peripapillary retinal nerve fibre layer(pRNFL) and macular segmented layers evaluation by optical coherence tomography(OCT).RESULTS: For the 0-18y cohort, the final BCVA(logMAR)was significantly better and less frequent recurrences than adult cohorts(P=0.000). The final BCVA(logMAR) in all age-cohorts of the ON patients had negative and linear correlations to the pRNFL thicknesses and macular retinal ganglion cell layer(mRGCL) volumes, when the pRNFL thicknesses were reduced to the thresholds of 57.2-67.5 μm or 0.691-0.737 mm;in mRGCL volumes, respectively, with the strongest interdependence in the 19-40y cohort. The ON patients from varying age cohorts would be threatened by blindness when their pRNFL thicknesses dropped 36.7-48.3 μm or the mRGCL volumes dropped to 0.495-0.613 mm;.CONCLUSION: The paediatric ON has best prognosis and young adult ON exhibits perfectly linear correlations of final vision and structural loss. The pRNFL and the mRGCL could be potential structural markers to predict the vision prognosis for varying-age ON patients. 展开更多
关键词 optic neuritis age-cohort final visual acuity structural impairment linear correlations
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Computer Modeling and Simulation Evaluation of High Power LED Sources for Secondary Optical Design 被引量:3
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作者 SU Hong-dong WANG Ya-jun DONG Ji-yang CHEN Zhong 《Semiconductor Photonics and Technology》 CAS 2007年第3期186-191,共6页
Proposed and demonstrated is a novel computer modeling method for high power light emitting diodes(LEDs). It contains geometrical structure and optical property of high power LED as well as LED dies definition with it... Proposed and demonstrated is a novel computer modeling method for high power light emitting diodes(LEDs). It contains geometrical structure and optical property of high power LED as well as LED dies definition with its spatial and angular distribution. Merits and non-merits of traditional modeling methods when applied to high power LEDs based on secondary optical design are discussed. Two commercial high power LEDs are simulated using the proposed computer modeling method. Correlation coefficient is proposed to compare and analyze the simulation results and manufacturing specifications. The source model is precisely demonstrated by obtaining above 99% in correlation coefficient with different surface incident angle intervals. 展开更多
关键词 high power LEDs solid-state lighting SIMULATION ray tracing secondary optical design correlation coefficient
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Fresnel incoherent correlation holography with single camera shot 被引量:2
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作者 Anand Vijayakumar Tomas Katkus +4 位作者 Stefan Lundgaard Denver P.Linklater Elena P.Ivanova Soon Hock Ng Saulius Juodkazis 《Opto-Electronic Advances》 2020年第8期12-22,共11页
Fresnel incoherent correlation holography(FINCH)is a self-interference based super-resolution three-dimensional imaging technique.FINCH in inline configuration requires an active phase modulator to record at least thr... Fresnel incoherent correlation holography(FINCH)is a self-interference based super-resolution three-dimensional imaging technique.FINCH in inline configuration requires an active phase modulator to record at least three phase-shifted camera shots to reconstruct objects without twin image and bias terms.In this study,FINCH is realized using a randomly multiplexed bifocal binary diffractive Fresnel zone lenses fabricated using electron beam lithography.The object space is calibrated by axially scanning a point object along the optical axis and recording the corresponding point spread holograms(PSHs).An object is mounted within the calibrated object space,and the object hologram was recorded under identical experimental conditions used for recording the PSHs.The image of the object at different depths was reconstructed by a cross-correlation between the object hologram and the PSHs.Application potential including bio-medical optics is discussed. 展开更多
关键词 IMAGING HOLOGRAPHY correlation three-dimensional imaging diffractive optics
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An Improved Optical Flow Method for Image Registration with Large-scale Movements 被引量:6
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作者 XIONG Jing-Yi LUO Yu-Pin TANG Guang-Rong 《自动化学报》 EI CSCD 北大核心 2008年第7期760-764,共5页
在这份报纸,为图象登记的一个改进光流动方法被建议。它以它与一个起始的运动评估者改进光流动方法的方法是新奇的:扩大了阶段关联技术(EPCT ) ,用补偿前者的缺乏的后者的优点。以一种更多的详细方式,光流动方法能到达亚象素精确性... 在这份报纸,为图象登记的一个改进光流动方法被建议。它以它与一个起始的运动评估者改进光流动方法的方法是新奇的:扩大了阶段关联技术(EPCT ) ,用补偿前者的缺乏的后者的优点。以一种更多的详细方式,光流动方法能到达亚象素精确性并且计算象啁啾并且倾斜一样的复杂失真模式,这能被说但是与大规模运动弱。因为 EPCT 用象素水平精确性盖住大翻译和旋转的大小并且在精明的负担是有效的,它能为光流动方法被当作一个好起始的运动评估者。测试证明了特别,这个改进方法将显著地与大规模运动为图象提高登记表演并且对随机的噪音柔韧。 展开更多
关键词 图象处理 光流计算法 运动过程 运动图像
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Corrective Change of Retinal Thickness Measured by Optical Coherence Tomography and Histologic Studies 被引量:3
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作者 GeJ LuoRJ 《眼科学报》 1999年第3期153-153,共1页
Purpose:To evaluate the correlation of retinal thickness between optical coherence tomography(OCT)images and histologic slides.Methods:Retinal thickness was measured in 16 rabbit retinal histologic slides.The same eye... Purpose:To evaluate the correlation of retinal thickness between optical coherence tomography(OCT)images and histologic slides.Methods:Retinal thickness was measured in 16 rabbit retinal histologic slides.The same eyes has been previously measured by OCT fr the comparison of results between two methods.Retinal thickness of each OCT image section was measured using both the manually assisted(requiring localization of reflectivity peaks by observer)and automated modes of the computer software.Results:Retinal thickness measured by OCT demonstrated a high degree of correlation with retinal histologic study.The automated method(Cc=0.66,P<0.01) was less reliable than the manually assisted one (Cc=0.84,P<0.001).The former had an error in 95% confidence interval,ranged between-0.71 and 11.09μm.The latter had a less error,ranged from -2.99 to 5.13μm.Conclusion:OCT can quantitatively measure the retinal thickness.However,automatical identification of the reflective boundaries by computer may result in errors in some cases.To masure the retinal thickess by manually assisted mode can increase the accuracy. 展开更多
关键词 光内聚 CT 视网膜厚度 组织学
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Spatial correlation properties and phase singularity annihilation of Gaussian Schell-model beams in the focal region
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作者 刘普生 潘留占 吕百达 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第5期1752-1757,共6页
By using the generalized Debye diffraction integral, this paper studies the spatial correlation properties and phase singularity annihilation of apertured Gaussian Schell-model (GSM) beams in the focal region. It is... By using the generalized Debye diffraction integral, this paper studies the spatial correlation properties and phase singularity annihilation of apertured Gaussian Schell-model (GSM) beams in the focal region. It is shown that the width of the spectral degree of coherence can be larger, less than or equal to the corresponding width of spectral density, which depends not only on the scalar coherence length of the beams, but also on the truncation parameter. With a gradual increase of the truncation parameter, a pair of phase singularities of the spectral degree of coherence in the focal plane approaches each other, resulting in subwavelength structures. Finally, the annihilation of pairs of phase singularities takes place at a certain value of the truncation parameter. With increasing scalar coherence length, the annihilation occurs at the larger truncation parameter. However, the creation process of phase singularities outside the focal plane is not found for GSM beams. 展开更多
关键词 singular optics spatial correlation annihilation of phase singularities truncation parameter
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Research on Measurement Technology of Flue Gas Velocity Based on Optical Scintillation Induced by Fluctuation of Particulate Concentration
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作者 Zhibo Ni Tao Pang +1 位作者 Yang Yang Fengzhong Dong 《Journal of Environmental Protection》 2014年第10期905-913,共9页
Based on the theory of optical scintillation induced by fluctuation of particulate concentration, a Gas Flow Velocity Measurement System (GFVMS) is proposed to measure the gas flow velocity in stack. Verification expe... Based on the theory of optical scintillation induced by fluctuation of particulate concentration, a Gas Flow Velocity Measurement System (GFVMS) is proposed to measure the gas flow velocity in stack. Verification experiments on simulation flue indicate that, for the smoothing effect of transmitting and receiving apertures, optical scintillation induced by refractive index fluctuation is very weak. When particles are added into gas flow, the standard deviation of optical scintillation increased obviously. And when the particulate number concentration exceeds 4000/m3, the GFVMS can work normally, and the variation range of measured velocities is almost the same with that of Pitot tube. Sensitivity testing results show that, GFVMS is very sensitive to velocity change. Results of outfield experiment prove that, velocities measured by GFVMS are more stable and the average velocity (7.62/s) is very close to the statistical average (7.61 m/s) of velocities measured by Pitot tube at different points along optical path. 展开更多
关键词 optical Scintillation FLUE Gas VELOCITY PARTICULATE CONCENTRATION Cross correlation
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Mountain Glacier Flow Velocities Analyzed from Satellite Optical Images
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作者 Lei Huang Zhen Li 《Research in Cold and Arid Regions》 2010年第1期59-66,共8页
Mountain glaciers are sensitive to environment. It is important to acquire ice flow velocities over time for glacier research and hazard forecast. For this paper, cross-correlating of optical images is used to monitor... Mountain glaciers are sensitive to environment. It is important to acquire ice flow velocities over time for glacier research and hazard forecast. For this paper, cross-correlating of optical images is used to monitor ice flow velocities, and an improvement, which is called "moving grid," is made to this method. For this research, two remote-sensing images in a certain glacier area, dur-ing different times are selected. The first image is divided into grids, and we calculated the correlation coefficient of each window in the grid with the window on the second image. The window with the highest correlation coefficient is considered the counter-part one on the first image. The displacement of the two corresponding windows is the movement of the glacier, and it is used to calculate glacier surface velocity. Compared to the traditional way of dividing an image with ascertain grid, this method uses small steps to move the grid from one location to another adjacent location until the whole glacier area is covered in the image, thus in-creasing corresponding point density. We selected a glacier in the Tianshan Mountains for this experiment and used two re-mote-sensing images with a 10-year interval to determine this method. 展开更多
关键词 glacier flow satellite optical image correlation grid
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Effects of Relaxation and Correlation on Lifetime of Met ast able 6s[3/2]_2 State of Atomic Xenon
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作者 Dong Chenzhong, Xie Luyou, Ma Xinwen and Stephan Pritzsche Department of Physics, Northwest Normal University, Lanzhou. Department of Physics, University of Kassel, Germany. 《IMP & HIRFL Annual Report》 2001年第1期89-89,共1页
A high precision measurement of the lifetime of the 6s[3/2]_2 state in XeI, which has been carried out recently at a magnetic optic trap (MOT) equipment by Walhout et al.~[1], showed a rather large difference from the... A high precision measurement of the lifetime of the 6s[3/2]_2 state in XeI, which has been carried out recently at a magnetic optic trap (MOT) equipment by Walhout et al.~[1], showed a rather large difference from the prediction of Small-Warren et al.~[2] by about a factor of 3. In order to explain this discrepancy, Indelicato 展开更多
关键词 correlation LIFETIME ATOMIC Warren RELAXATION EXPLAIN optic metastable Teacher occupied
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基于多时相光学遥感影像亚像素相关的边坡监测——以溪洛渡电站为例 被引量:1
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作者 叶江 李才艺 +2 位作者 高红旗 徐卫红 向南松 《测绘通报》 CSCD 北大核心 2024年第1期38-43,108,共7页
水电站高边坡监测是水电站灾害防治中的关键问题,基于卫星遥感技术进行库区滑坡监测是解决该问题的重要手段之一。利用卫星影像亚像素相关性算法获取地表形变位移场,能够克服SAR影像失相关因素,在水电站边坡监测中具有重大的应用潜力。... 水电站高边坡监测是水电站灾害防治中的关键问题,基于卫星遥感技术进行库区滑坡监测是解决该问题的重要手段之一。利用卫星影像亚像素相关性算法获取地表形变位移场,能够克服SAR影像失相关因素,在水电站边坡监测中具有重大的应用潜力。本文以溪洛渡电站2015-2019年5期Google Earth影像和2019-2022年4期Sentinel-2影像为数据源,采用相位相关算法计算了边坡形变量,通过构建一次多项式曲面拟合模型去除轨道误差等趋势性误差,获取了2016、2017和2019年溪洛渡电站下游边坡形变值。分析显示,两种影像提取得到的边坡形变量具有相同的变化趋势,均与谷幅实测数据吻合较好。本文结果验证了基于多时相遥感数据将亚像素相关性匹配技术运用于大型水电站边坡形变监测的可行性。 展开更多
关键词 边坡监测 光学遥感影像 亚像素相关 趋势误差
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