The unique property of chirality is widely used in various fields.In the past few decades,a great deal of research has been conducted on the interactions between light and matter,resulting in significant technical adv...The unique property of chirality is widely used in various fields.In the past few decades,a great deal of research has been conducted on the interactions between light and matter,resulting in significant technical advancements in the precise manipulation of light field wavefronts.In this review,which focuses on current chiral optics research,we introduce the fundamental theory of chirality and highlight the latest achievements in enhancing chiral signals through artificial nano-manufacturing technology,with a particular focus on mechanisms such as light scattering and Mie resonance used to amplify chiral signals.By providing an overview of enhanced chiral signals,this review aims to provide researchers with an indepth understanding of chiral phenomena and its versatile applications in various domains.展开更多
This study proposes a novel radar echo extrapolation algorithm,OF-ConvGRU,which integrates Optical Flow(OF)and Convolutional Gated Recurrent Unit(ConvGRU)methods for improved nowcasting.Using the Standardized Radar Da...This study proposes a novel radar echo extrapolation algorithm,OF-ConvGRU,which integrates Optical Flow(OF)and Convolutional Gated Recurrent Unit(ConvGRU)methods for improved nowcasting.Using the Standardized Radar Dataset of the Guangdong-Hong Kong-Macao Greater Bay Area,the performance of OF-ConvGRU was evaluated against OF and ConvGRU methods.Threat Score(TS)and Bias Score(BIAS)were employed to assess extrapolation accuracy across various echo intensities(20-50 dBz)and weather phenomena.Results demonstrate that OF-ConvGRU significantly enhances prediction accuracy for moderate-intensity echoes(30-40 dBz),effectively combining OF s precise motion estimation with ConvGRU s nonlinear learning capabilities.However,challenges persist in low-intensity(20 dBz)and high-intensity(50 dBz)echo predictions.The study reveals distinct advantages of each method in specific contexts,highlighting the importance of multi-method approaches in operational nowcasting.OF-ConvGRU shows promise in balancing short-term accuracy with long-term stability,particularly for complex weather systems.展开更多
Overt and harmful diabetes mellitus(DM)has detrimental effects on individuals and,by extension,the community.Among the microvascular DM complications is diabetic retinopathy(DR).DR may cause irreversible vision deteri...Overt and harmful diabetes mellitus(DM)has detrimental effects on individuals and,by extension,the community.Among the microvascular DM complications is diabetic retinopathy(DR).DR may cause irreversible vision deterioration in cases of poor blood glucose regulation.Changes in vascular permeability are key trigger points for diabetic macular edema(DME),a condition characterized by the accumulation of fluid in the macula.The development of vascular endothelial growth factor(VEGF)pathway inhibitors has provided a pathogenesis-based treatment approach for DME.Optical coherence tomography(OCT)provides highresolution imaging of the anatomy,including the aging of DME and its structural damage,in distinct morphologic subtypes of macular edema,thereby supporting the assessment of macular edema treatment.The availability of repeated OCT monitoring provides clinical reassurance through the treatment.OCT angiography(OCTA)provides retinal blood flow maps with high spatial resolution.The ability promotes an understanding of disease pathogenesis and facilitates the implementation of new therapeutic methods.This review compares the potential of OCT and OCTA in the diagnosis and treatment of DME,as well as their respective therapeutic applications.展开更多
In the realm of secure information storage,optical encryption has emerged as a vital technique,particularly with the miniaturization of encryption devices.However,many existing systems lack the necessary reconfigurabi...In the realm of secure information storage,optical encryption has emerged as a vital technique,particularly with the miniaturization of encryption devices.However,many existing systems lack the necessary reconfigurability and dynamic functionality.This study presents a novel approach through the development of dynamic optical-to-chemical energy conversion metamaterials,which enable enhanced steganography and multilevel information storage.We introduce a micro-dynamic multiple encryption device that leverages programmable optical properties in coumarin-based metamaterials,achieved through a direct laser writing grayscale gradient strategy.This methodology allows for the dynamic regulation of photoluminescent characteristics and cross-linking networks,facilitating innovative steganographic techniques under varying light conditions.The integration of a multi-optical field control system enables real-time adjustments to the material’s properties,enhancing the device’s reconfigurability and storage capabilities.Our findings underscore the potential of these metamaterials in advancing the field of microscale optical encryption,paving the way for future applications in dynamic storage and information security.展开更多
The advantages of read-only storage is the predominance of optical recording relative to magnetic and other rewritable methods. Multilevel （ML） read-only technology has been a trend to improve the data capacity and ...The advantages of read-only storage is the predominance of optical recording relative to magnetic and other rewritable methods. Multilevel （ML） read-only technology has been a trend to improve the data capacity and transfer rate. Based on the principle and coding method of ML, this paper demonstrates some ML read-only recording methods, of which a new ML read-only recording is developed. This recording method integrates amplitude modulation achieved by the reaction mechanism of physics and chemistry of photoresist with the run-length-limited technology. The discs can be achieved using standard photoresist mastering and replication techniques with great compatibility to conventional binary read-only discs.展开更多
Directly buried metal optical cable is a form of erecting optical fiber ring network communication system in wind farms. Although the directly buried optical cable is much less than the overhead optical cable affected...Directly buried metal optical cable is a form of erecting optical fiber ring network communication system in wind farms. Although the directly buried optical cable is much less than the overhead optical cable affected by lightning, sometimes lightning damaging optical cable and flashover discharge accidents of optical cable port occurred. In this paper, the amplitude spectrum of lightning wave, the breakdown depth and breakdown distance of lightning wave to soil, the metal components of optical cable port and the impedance characteristics of grounding wire are systematically analyzed, and the prevention methods of directly buried optical cable in wind farm to avoid lightning damage are proposed.展开更多
Non-destructive testing (NDT) of structures is one of the most important tasksof the proper maintenance and diagnosis of machines and constructions structuralcondition. NDT methods contribute to the damage tolerance p...Non-destructive testing (NDT) of structures is one of the most important tasksof the proper maintenance and diagnosis of machines and constructions structuralcondition. NDT methods contribute to the damage tolerance philosophy used in theaircraft design methodology as well as many other operation and maintenance programsof machinery and constructions. The following study is focusing on overviewing animportant group of NDT methods: the optical and other ones, which found broadapplicability in scientific and industrial studies nowadays. The paper discusses theselected most widely applicable methods, namely, visual testing, ultrasonic testing,radiographic testing, infrared thermography as well as electronic speckle patterninterferometry and shearographic testing. Besides the basic principles of testing usingthese methods, their potential applications in various industrial and technologicalbranches are broadly discussed. The analysis as categorization of the NDT methodsprovided in this paper may help in selection of such methods in diagnosis of varioustypes of structures and defects and damage occurring in these structures.展开更多
The nano-particle-based planar laser scattering （NPLS） technique is used to measure the density distribution in the supersonic mixing layer of the convective Mach number 0.12, and the optical path difference （OPL）...The nano-particle-based planar laser scattering （NPLS） technique is used to measure the density distribution in the supersonic mixing layer of the convective Mach number 0.12, and the optical path difference （OPL）, which is quite crucial for the study of aero-optics, is obtained by post processing. Based on the high spatiotemporal resolutions of the NPLS, the structure of the OPL is ana]ysed using wavelet methods. The coherent structures of the OPL are extracted using three methods, including the methods of thresholding the coefficients of the orthogonal wavelet transform and the wavelet packet transform, and preserving a number of wavelet packet coefficients with the largest amplitudes determined by the entropy dimension. Their performances are compared, and the method using the wavelet packet is the best. Based on the viewpoint of multifractals, we study the OPL by the wavelet transform maxima method （WTMM）, and the result indicates that its scaling behaviour is evident.展开更多
In this article, four kinds of optical emission spectroscopic methods of determining electron temperature are used to investigate the relationship between electron temperature and pressure in the cylindrical plasmas o...In this article, four kinds of optical emission spectroscopic methods of determining electron temperature are used to investigate the relationship between electron temperature and pressure in the cylindrical plasmas of dc glow discharges at low pressures in laboratory by measuring the relative intensities of ArI lines at various pressures. These methods are developed respectively on the basis of the Fermi-Dirac model, corona model, and two kinds of electron collision cross section models according to the kinetic analysis. Their theoretical bases and the conditions to which they are applicable are reviewed, and their calculation results and fitting errors are compared with each other. The investigation has indicated that the electron temperatures obtained by the four methods become consistent with each other when the pressure increases in the low pressure argon plasmas.展开更多
The optical reflectance and transmittance spectra in the wavelength range of 300-2500 nm are used to compute the absorption coefficient of zinc oxide films annealed at different post-annealing temperatures 400, 500 an...The optical reflectance and transmittance spectra in the wavelength range of 300-2500 nm are used to compute the absorption coefficient of zinc oxide films annealed at different post-annealing temperatures 400, 500 and 600°C.The values of the cross point between the curves of the real and imaginary parts of the optical conductivity ɑ_1 and ɑ_1 with energy axis of films exhibit values that correspond to optical gaps and are about 3.25-3.3 eV. The maxima of peaks in plots dR/dλ and dT/dλ versus wavelength of films exhibit optical gaps at about 3.12-3.25 eV.The values of the fundamental indirect band gap obtained from the Tauc model are at about 3.14-3.2 eV. It can be seen that films annealed at 600°C have the minimum indirect optical band gap at about 3.15 eV. The films annealed at 600°C have Urbach＇s energy minimum of 1.38 eV and hence have minimum disorder. The dispersion energy d of films annealed at 500°C has the minimum value of 43 eV.展开更多
We evaluate the applicability of an optical transmission measurement method commonly used for the analysis of the Black Carbon (BC) content of aerosol sample, to determine the BC content of loess sediments. A number o...We evaluate the applicability of an optical transmission measurement method commonly used for the analysis of the Black Carbon (BC) content of aerosol sample, to determine the BC content of loess sediments. A number of different sample pretreatment procedures are developed and compared, leading to an optimum preparation process. The results include: 1) Subtraction of the optical attenuation values before and after heating of the sample filters (“ΔATN”) varies linearly with the sample mass. The slope of the regression line provides the best determination of BC concentration. 2) When the sample mass is small, (NaPO3)6 pretreatment is best for BC measurement, and the BC concentration results are given by the slope of the regression between ΔATN and sample mass, for a series of samples of varying mass. 3) HF pretreatment accompanied by centrifugation and rinsing may produce a negative bias on the result. 4) Replicate measurements of BC for loess samples showed a maximum deviation less than 5.6%, suggesting that measurements of the BC concentration of a sequence of loess samples could determine variations to this degree of significance. 5) The overall trends of BC concentration in loess section sequences were similar for all chemical pretreatments. The BC concentration result for replicate samples is comparable when pretreated by the same procedure.展开更多
This peper discusses engineering methods of optical fiber connection in WAN (Wide Area Network)and introduces three available solutions with their characteristics analyzed. A group of special testing data is giveu acc...This peper discusses engineering methods of optical fiber connection in WAN (Wide Area Network)and introduces three available solutions with their characteristics analyzed. A group of special testing data is giveu according to the definite project.展开更多
The direct calculation models of spectral transmittance of single and double slabs consisted of semitransparent solid materials were developed based on ray trace method, and a new inversion method of optical constants...The direct calculation models of spectral transmittance of single and double slabs consisted of semitransparent solid materials were developed based on ray trace method, and a new inversion method of optical constants （k is extinction coefficient and n is refractive index ） of materials was proposed based on transmittance spectrograms of double slabs. Differences between the new method and two others currently used methods were studied, and application range of methods was also investigated. Optical constants of selenide glass attained in references were selected as true values, and spectral transmittances of glass simulated based on direct calculation model were regarded as experimental values. Optical constants of selenide glass were achieved by inverse models. Influences of measurement error on inverse results were also determined. The results showed that ： （ 1 ） based on transmittance spectrograms of double slabs in which thickness of single slab is the same, the new proposed method can attain optical constants of materials; （2） the effect of optical constants n and k on three inversion methods are urgent larger, but inversed calculation precision of optical constants are higher in most application ranges ; （ 3 ） the influence of measurement errors existed in experimental datum on the inverse precision of three methods are urgent distinctness.展开更多
Possible early diagnostic application of optical methods (dielectrophoresis, spectral and imaging ellipsometry, Fourier-transform infrared spectroscopy, Raman spectroscopy) in studies of red blood cells and serum of p...Possible early diagnostic application of optical methods (dielectrophoresis, spectral and imaging ellipsometry, Fourier-transform infrared spectroscopy, Raman spectroscopy) in studies of red blood cells and serum of patients with diffuse liver disease with varying degrees of fibrosis has been evaluated. Application of combined optical methods was confirmed to significantly improve the performance of sensitivity, specificity, and accuracy index as well as to achieve the reliable results in diagnosis of both severe fibrosis and slight ulterior liver fibrosis. Identified diagnostic potential of optical methods can be effectively utilized in noninvasive screening evaluation of stages of diffuse liver disease of various geneses.展开更多
In the medical field, there are growing interests in applied research such as in vivo fluorescence monitoring because of excellent body transmission characteristic of the near-infrared light. However, optical noise by...In the medical field, there are growing interests in applied research such as in vivo fluorescence monitoring because of excellent body transmission characteristic of the near-infrared light. However, optical noise by excitation light and illumination equipment for medical applications such as interior light, surgical light decrease efficiency of the fluorescent signal when observers such as surgeons confirm fluorescence signals in medical field. To solve these problems in medical field, we have analyzed external noise factors by effect on image realization, quantification of optical noise generation by external factors, and have suggested methods of minimize the optical noise in this paper. In case of fluorescence imaging in the operating room, it has been confirmed that fluorescent excitation light, interior light and surgical light are factors to generate optical noise. To acquire near-infrared fluorescence images and to compare fluorescence contrast under conditions of darkroom, interior light and surgical light, light emitting diodes (LEDs) sources that have peak wavelength at 740, 760 and 780 nm respectively were used as excitation light sources. In addition, short-pass filter which has transmission edge at 775 nm has been applied to minimize the optical noise in each external noise factor. By comparing contrast of each image before and after use of the short-pass filter, we confirmed that optical noise reduced 49%, 56% and 66% in external noise factors respectively.展开更多
The rapid development in the field of optic in the past decade demonstrates a potential for cancer diagnosis using optical technologies. This review highlights the principle and advantages of using optical technologie...The rapid development in the field of optic in the past decade demonstrates a potential for cancer diagnosis using optical technologies. This review highlights the principle and advantages of using optical technologies, and focuses on their application in tumor diagnosis and their limitation in clinical uses. These optical technologies are rapid methods,which can provide a great deal of different information from conventional methods, while,it still requires clinical trial studies to develop and ensure the applicability of these optical technologies for clinical cancer diagnosis.展开更多
Optical microscopy has become an indispensable tool for visualizing sub-cellular structures andbiological processes.However,scattering in biological tissues is a major obstacle that preventshigh-resolution images from...Optical microscopy has become an indispensable tool for visualizing sub-cellular structures andbiological processes.However,scattering in biological tissues is a major obstacle that preventshigh-resolution images from being obtained from deep regions of tissue.We review commontechniques,such as multiphoton microscopy(MPM)and optical coherence microscopy(OCM),for diffraction limited imaging beyond an imaging depth of 0.5 mm.Novel implementations havebeen emerging in recent years giving higher imaging speed,deeper penetration,and better imagequality.Focal modulation microscopy(FMM)is a novel method that combines confocal spatialfltering with focal modulation to reject out-of-focus background.FMM has demonstrated animaging depth comparable to those of MPM and OCM,near-real-time image acquisition,and thecapability for multiple contrast mechanisms.展开更多
Learning-based methods have been proved to perform well in a variety of areas in the biomedical field,such as biomedical image segmentation,and histopathological image analysis.Deep learning,as the most recently prese...Learning-based methods have been proved to perform well in a variety of areas in the biomedical field,such as biomedical image segmentation,and histopathological image analysis.Deep learning,as the most recently presented approach of learning-based methods,has attracted more and more attention.For instance,massive researches of deep learning methods for image reconstructions of computed tomography(CT)and magnetic resonance imaging(MRI)have been reported,indicating the great potential of deep learning for inverse problems.Optical technology-related medical imaging modalities including diffuse optical tomography(DOT),fluorescence molecular tomography(FMT),bioluminescence tomography(BLT),and photo-acoustic tomography(PAT)are also dramatically innovated by introducing learning-based methods,in particular deep learning methods,to obtain better reconstruction results.This review depicts the latest researches on learning based optical tomography of DOT,FMT,BLT,and PAT.According to the most recent studies,learning-based methods applied in the field of optical tomography are categorized as kernel-based methods and deep learning methods.In this review,the former are regarded as a sort of conventional learning-based methods and the latter are subdivided into model-based methods,post-processing methods,and end-to-end methods.Algorithm as well as data acquisition strategy are discussed in this review.The evaluations of these methods are summarized to ilustrate the performance of deep learning-based reconstruction.展开更多
Modal parameters can accurately characterize the structural dynamic properties and assess the physical state of the structure.Therefore,it is particularly significant to identify the structural modal parameters accordi...Modal parameters can accurately characterize the structural dynamic properties and assess the physical state of the structure.Therefore,it is particularly significant to identify the structural modal parameters according to the monitoring data information in the structural health monitoring(SHM)system,so as to provide a scientific basis for structural damage identification and dynamic model modification.In view of this,this paper reviews methods for identifying structural modal parameters under environmental excitation and briefly describes how to identify structural damages based on the derived modal parameters.The paper primarily introduces data-driven modal parameter recognition methods(e.g.,time-domain,frequency-domain,and time-frequency-domain methods,etc.),briefly describes damage identification methods based on the variations of modal parameters(e.g.,natural frequency,modal shapes,and curvature modal shapes,etc.)and modal validation methods(e.g.,Stability Diagram and Modal Assurance Criterion,etc.).The current status of the application of artificial intelligence(AI)methods in the direction of modal parameter recognition and damage identification is further discussed.Based on the pre-vious analysis,the main development trends of structural modal parameter recognition and damage identification methods are given to provide scientific references for the optimized design and functional upgrading of SHM systems.展开更多
Two optical methods, namely crystal facet reflection and etching pits reflection, were used to orient and high-purity germanium crystals. The X-ray diffraction patterns of three slices that were cut from the oriented ...Two optical methods, namely crystal facet reflection and etching pits reflection, were used to orient and high-purity germanium crystals. The X-ray diffraction patterns of three slices that were cut from the oriented and crystals were measured by X-ray diffraction. The experimental errors of crystal facet reflection method and etching pits reflection method are in the range of 0.05° - 0.12°. The crystal facet reflection method and etching pits reflection method are extremely simple and cheap and their accuracies are acceptable for characterizing high purity detector-grade germanium crystals.展开更多
基金funded by the National Natural Science Foundation of China(62005168,62075132,and 92050202)the Natural Science Foundation of Shanghai(22ZR1443100).
文摘The unique property of chirality is widely used in various fields.In the past few decades,a great deal of research has been conducted on the interactions between light and matter,resulting in significant technical advancements in the precise manipulation of light field wavefronts.In this review,which focuses on current chiral optics research,we introduce the fundamental theory of chirality and highlight the latest achievements in enhancing chiral signals through artificial nano-manufacturing technology,with a particular focus on mechanisms such as light scattering and Mie resonance used to amplify chiral signals.By providing an overview of enhanced chiral signals,this review aims to provide researchers with an indepth understanding of chiral phenomena and its versatile applications in various domains.
基金Scientific Research and Development Project of Hebei Meteorological Bureau(23ky08).
文摘This study proposes a novel radar echo extrapolation algorithm,OF-ConvGRU,which integrates Optical Flow(OF)and Convolutional Gated Recurrent Unit(ConvGRU)methods for improved nowcasting.Using the Standardized Radar Dataset of the Guangdong-Hong Kong-Macao Greater Bay Area,the performance of OF-ConvGRU was evaluated against OF and ConvGRU methods.Threat Score(TS)and Bias Score(BIAS)were employed to assess extrapolation accuracy across various echo intensities(20-50 dBz)and weather phenomena.Results demonstrate that OF-ConvGRU significantly enhances prediction accuracy for moderate-intensity echoes(30-40 dBz),effectively combining OF s precise motion estimation with ConvGRU s nonlinear learning capabilities.However,challenges persist in low-intensity(20 dBz)and high-intensity(50 dBz)echo predictions.The study reveals distinct advantages of each method in specific contexts,highlighting the importance of multi-method approaches in operational nowcasting.OF-ConvGRU shows promise in balancing short-term accuracy with long-term stability,particularly for complex weather systems.
文摘Overt and harmful diabetes mellitus(DM)has detrimental effects on individuals and,by extension,the community.Among the microvascular DM complications is diabetic retinopathy(DR).DR may cause irreversible vision deterioration in cases of poor blood glucose regulation.Changes in vascular permeability are key trigger points for diabetic macular edema(DME),a condition characterized by the accumulation of fluid in the macula.The development of vascular endothelial growth factor(VEGF)pathway inhibitors has provided a pathogenesis-based treatment approach for DME.Optical coherence tomography(OCT)provides highresolution imaging of the anatomy,including the aging of DME and its structural damage,in distinct morphologic subtypes of macular edema,thereby supporting the assessment of macular edema treatment.The availability of repeated OCT monitoring provides clinical reassurance through the treatment.OCT angiography(OCTA)provides retinal blood flow maps with high spatial resolution.The ability promotes an understanding of disease pathogenesis and facilitates the implementation of new therapeutic methods.This review compares the potential of OCT and OCTA in the diagnosis and treatment of DME,as well as their respective therapeutic applications.
基金the National Key R&D Program of China(Project No.2022YFB4700100)National Natural Science Foundation of China(Grant Nos.61973298)+2 种基金Hong Kong Research Grants Council(GRF Project Number 11216120)the CAS-RGC Joint Laboratory Funding Scheme(Project Number JLFS/E-104/18)the Innovation Promotion Research Association of the Chinese Academy of Sciences(NO.2022199)。
文摘In the realm of secure information storage,optical encryption has emerged as a vital technique,particularly with the miniaturization of encryption devices.However,many existing systems lack the necessary reconfigurability and dynamic functionality.This study presents a novel approach through the development of dynamic optical-to-chemical energy conversion metamaterials,which enable enhanced steganography and multilevel information storage.We introduce a micro-dynamic multiple encryption device that leverages programmable optical properties in coumarin-based metamaterials,achieved through a direct laser writing grayscale gradient strategy.This methodology allows for the dynamic regulation of photoluminescent characteristics and cross-linking networks,facilitating innovative steganographic techniques under varying light conditions.The integration of a multi-optical field control system enables real-time adjustments to the material’s properties,enhancing the device’s reconfigurability and storage capabilities.Our findings underscore the potential of these metamaterials in advancing the field of microscale optical encryption,paving the way for future applications in dynamic storage and information security.
基金Project supported by the National Natural Science Foundation of China （Grant No 60577035）.
文摘The advantages of read-only storage is the predominance of optical recording relative to magnetic and other rewritable methods. Multilevel （ML） read-only technology has been a trend to improve the data capacity and transfer rate. Based on the principle and coding method of ML, this paper demonstrates some ML read-only recording methods, of which a new ML read-only recording is developed. This recording method integrates amplitude modulation achieved by the reaction mechanism of physics and chemistry of photoresist with the run-length-limited technology. The discs can be achieved using standard photoresist mastering and replication techniques with great compatibility to conventional binary read-only discs.
基金Supported by Regional Lightning Protection Engineering Technology Research and Development Project in Guangdong Yuedian Dianbai Wind Farm (GDW-PK-21022 Phase II)。
文摘Directly buried metal optical cable is a form of erecting optical fiber ring network communication system in wind farms. Although the directly buried optical cable is much less than the overhead optical cable affected by lightning, sometimes lightning damaging optical cable and flashover discharge accidents of optical cable port occurred. In this paper, the amplitude spectrum of lightning wave, the breakdown depth and breakdown distance of lightning wave to soil, the metal components of optical cable port and the impedance characteristics of grounding wire are systematically analyzed, and the prevention methods of directly buried optical cable in wind farm to avoid lightning damage are proposed.
文摘Non-destructive testing (NDT) of structures is one of the most important tasksof the proper maintenance and diagnosis of machines and constructions structuralcondition. NDT methods contribute to the damage tolerance philosophy used in theaircraft design methodology as well as many other operation and maintenance programsof machinery and constructions. The following study is focusing on overviewing animportant group of NDT methods: the optical and other ones, which found broadapplicability in scientific and industrial studies nowadays. The paper discusses theselected most widely applicable methods, namely, visual testing, ultrasonic testing,radiographic testing, infrared thermography as well as electronic speckle patterninterferometry and shearographic testing. Besides the basic principles of testing usingthese methods, their potential applications in various industrial and technologicalbranches are broadly discussed. The analysis as categorization of the NDT methodsprovided in this paper may help in selection of such methods in diagnosis of varioustypes of structures and defects and damage occurring in these structures.
基金Projected supported by the Innovation Research Foundations for Postgraduates of National University of Defense Technology and Hunan Provincethe National Natural Science Foundation of China (Grant No. 61008037)
文摘The nano-particle-based planar laser scattering （NPLS） technique is used to measure the density distribution in the supersonic mixing layer of the convective Mach number 0.12, and the optical path difference （OPL）, which is quite crucial for the study of aero-optics, is obtained by post processing. Based on the high spatiotemporal resolutions of the NPLS, the structure of the OPL is ana]ysed using wavelet methods. The coherent structures of the OPL are extracted using three methods, including the methods of thresholding the coefficients of the orthogonal wavelet transform and the wavelet packet transform, and preserving a number of wavelet packet coefficients with the largest amplitudes determined by the entropy dimension. Their performances are compared, and the method using the wavelet packet is the best. Based on the viewpoint of multifractals, we study the OPL by the wavelet transform maxima method （WTMM）, and the result indicates that its scaling behaviour is evident.
文摘In this article, four kinds of optical emission spectroscopic methods of determining electron temperature are used to investigate the relationship between electron temperature and pressure in the cylindrical plasmas of dc glow discharges at low pressures in laboratory by measuring the relative intensities of ArI lines at various pressures. These methods are developed respectively on the basis of the Fermi-Dirac model, corona model, and two kinds of electron collision cross section models according to the kinetic analysis. Their theoretical bases and the conditions to which they are applicable are reviewed, and their calculation results and fitting errors are compared with each other. The investigation has indicated that the electron temperatures obtained by the four methods become consistent with each other when the pressure increases in the low pressure argon plasmas.
文摘The optical reflectance and transmittance spectra in the wavelength range of 300-2500 nm are used to compute the absorption coefficient of zinc oxide films annealed at different post-annealing temperatures 400, 500 and 600°C.The values of the cross point between the curves of the real and imaginary parts of the optical conductivity ɑ_1 and ɑ_1 with energy axis of films exhibit values that correspond to optical gaps and are about 3.25-3.3 eV. The maxima of peaks in plots dR/dλ and dT/dλ versus wavelength of films exhibit optical gaps at about 3.12-3.25 eV.The values of the fundamental indirect band gap obtained from the Tauc model are at about 3.14-3.2 eV. It can be seen that films annealed at 600°C have the minimum indirect optical band gap at about 3.15 eV. The films annealed at 600°C have Urbach＇s energy minimum of 1.38 eV and hence have minimum disorder. The dispersion energy d of films annealed at 500°C has the minimum value of 43 eV.
文摘We evaluate the applicability of an optical transmission measurement method commonly used for the analysis of the Black Carbon (BC) content of aerosol sample, to determine the BC content of loess sediments. A number of different sample pretreatment procedures are developed and compared, leading to an optimum preparation process. The results include: 1) Subtraction of the optical attenuation values before and after heating of the sample filters (“ΔATN”) varies linearly with the sample mass. The slope of the regression line provides the best determination of BC concentration. 2) When the sample mass is small, (NaPO3)6 pretreatment is best for BC measurement, and the BC concentration results are given by the slope of the regression between ΔATN and sample mass, for a series of samples of varying mass. 3) HF pretreatment accompanied by centrifugation and rinsing may produce a negative bias on the result. 4) Replicate measurements of BC for loess samples showed a maximum deviation less than 5.6%, suggesting that measurements of the BC concentration of a sequence of loess samples could determine variations to this degree of significance. 5) The overall trends of BC concentration in loess section sequences were similar for all chemical pretreatments. The BC concentration result for replicate samples is comparable when pretreated by the same procedure.
文摘This peper discusses engineering methods of optical fiber connection in WAN (Wide Area Network)and introduces three available solutions with their characteristics analyzed. A group of special testing data is giveu according to the definite project.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51176038 and 51106036)
文摘The direct calculation models of spectral transmittance of single and double slabs consisted of semitransparent solid materials were developed based on ray trace method, and a new inversion method of optical constants （k is extinction coefficient and n is refractive index ） of materials was proposed based on transmittance spectrograms of double slabs. Differences between the new method and two others currently used methods were studied, and application range of methods was also investigated. Optical constants of selenide glass attained in references were selected as true values, and spectral transmittances of glass simulated based on direct calculation model were regarded as experimental values. Optical constants of selenide glass were achieved by inverse models. Influences of measurement error on inverse results were also determined. The results showed that ： （ 1 ） based on transmittance spectrograms of double slabs in which thickness of single slab is the same, the new proposed method can attain optical constants of materials; （2） the effect of optical constants n and k on three inversion methods are urgent larger, but inversed calculation precision of optical constants are higher in most application ranges ; （ 3 ） the influence of measurement errors existed in experimental datum on the inverse precision of three methods are urgent distinctness.
文摘Possible early diagnostic application of optical methods (dielectrophoresis, spectral and imaging ellipsometry, Fourier-transform infrared spectroscopy, Raman spectroscopy) in studies of red blood cells and serum of patients with diffuse liver disease with varying degrees of fibrosis has been evaluated. Application of combined optical methods was confirmed to significantly improve the performance of sensitivity, specificity, and accuracy index as well as to achieve the reliable results in diagnosis of both severe fibrosis and slight ulterior liver fibrosis. Identified diagnostic potential of optical methods can be effectively utilized in noninvasive screening evaluation of stages of diffuse liver disease of various geneses.
文摘In the medical field, there are growing interests in applied research such as in vivo fluorescence monitoring because of excellent body transmission characteristic of the near-infrared light. However, optical noise by excitation light and illumination equipment for medical applications such as interior light, surgical light decrease efficiency of the fluorescent signal when observers such as surgeons confirm fluorescence signals in medical field. To solve these problems in medical field, we have analyzed external noise factors by effect on image realization, quantification of optical noise generation by external factors, and have suggested methods of minimize the optical noise in this paper. In case of fluorescence imaging in the operating room, it has been confirmed that fluorescent excitation light, interior light and surgical light are factors to generate optical noise. To acquire near-infrared fluorescence images and to compare fluorescence contrast under conditions of darkroom, interior light and surgical light, light emitting diodes (LEDs) sources that have peak wavelength at 740, 760 and 780 nm respectively were used as excitation light sources. In addition, short-pass filter which has transmission edge at 775 nm has been applied to minimize the optical noise in each external noise factor. By comparing contrast of each image before and after use of the short-pass filter, we confirmed that optical noise reduced 49%, 56% and 66% in external noise factors respectively.
文摘The rapid development in the field of optic in the past decade demonstrates a potential for cancer diagnosis using optical technologies. This review highlights the principle and advantages of using optical technologies, and focuses on their application in tumor diagnosis and their limitation in clinical uses. These optical technologies are rapid methods,which can provide a great deal of different information from conventional methods, while,it still requires clinical trial studies to develop and ensure the applicability of these optical technologies for clinical cancer diagnosis.
文摘Optical microscopy has become an indispensable tool for visualizing sub-cellular structures andbiological processes.However,scattering in biological tissues is a major obstacle that preventshigh-resolution images from being obtained from deep regions of tissue.We review commontechniques,such as multiphoton microscopy(MPM)and optical coherence microscopy(OCM),for diffraction limited imaging beyond an imaging depth of 0.5 mm.Novel implementations havebeen emerging in recent years giving higher imaging speed,deeper penetration,and better imagequality.Focal modulation microscopy(FMM)is a novel method that combines confocal spatialfltering with focal modulation to reject out-of-focus background.FMM has demonstrated animaging depth comparable to those of MPM and OCM,near-real-time image acquisition,and thecapability for multiple contrast mechanisms.
基金supported by the Fundamental Research Funds for Central Universities,the National Natural Science Foundation of China(No.61601019,61871022)the 111 Project(No.B13003).
文摘Learning-based methods have been proved to perform well in a variety of areas in the biomedical field,such as biomedical image segmentation,and histopathological image analysis.Deep learning,as the most recently presented approach of learning-based methods,has attracted more and more attention.For instance,massive researches of deep learning methods for image reconstructions of computed tomography(CT)and magnetic resonance imaging(MRI)have been reported,indicating the great potential of deep learning for inverse problems.Optical technology-related medical imaging modalities including diffuse optical tomography(DOT),fluorescence molecular tomography(FMT),bioluminescence tomography(BLT),and photo-acoustic tomography(PAT)are also dramatically innovated by introducing learning-based methods,in particular deep learning methods,to obtain better reconstruction results.This review depicts the latest researches on learning based optical tomography of DOT,FMT,BLT,and PAT.According to the most recent studies,learning-based methods applied in the field of optical tomography are categorized as kernel-based methods and deep learning methods.In this review,the former are regarded as a sort of conventional learning-based methods and the latter are subdivided into model-based methods,post-processing methods,and end-to-end methods.Algorithm as well as data acquisition strategy are discussed in this review.The evaluations of these methods are summarized to ilustrate the performance of deep learning-based reconstruction.
基金supported by the Innovation Foundation of Provincial Education Department of Gansu(2024B-005)the Gansu Province National Science Foundation(22YF7GA182)the Fundamental Research Funds for the Central Universities(No.lzujbky2022-kb01)。
文摘Modal parameters can accurately characterize the structural dynamic properties and assess the physical state of the structure.Therefore,it is particularly significant to identify the structural modal parameters according to the monitoring data information in the structural health monitoring(SHM)system,so as to provide a scientific basis for structural damage identification and dynamic model modification.In view of this,this paper reviews methods for identifying structural modal parameters under environmental excitation and briefly describes how to identify structural damages based on the derived modal parameters.The paper primarily introduces data-driven modal parameter recognition methods(e.g.,time-domain,frequency-domain,and time-frequency-domain methods,etc.),briefly describes damage identification methods based on the variations of modal parameters(e.g.,natural frequency,modal shapes,and curvature modal shapes,etc.)and modal validation methods(e.g.,Stability Diagram and Modal Assurance Criterion,etc.).The current status of the application of artificial intelligence(AI)methods in the direction of modal parameter recognition and damage identification is further discussed.Based on the pre-vious analysis,the main development trends of structural modal parameter recognition and damage identification methods are given to provide scientific references for the optimized design and functional upgrading of SHM systems.
文摘Two optical methods, namely crystal facet reflection and etching pits reflection, were used to orient and high-purity germanium crystals. The X-ray diffraction patterns of three slices that were cut from the oriented and crystals were measured by X-ray diffraction. The experimental errors of crystal facet reflection method and etching pits reflection method are in the range of 0.05° - 0.12°. The crystal facet reflection method and etching pits reflection method are extremely simple and cheap and their accuracies are acceptable for characterizing high purity detector-grade germanium crystals.
