We present a full three-dimensional, featured-data algorithm for time-domain fluorescence diffuse optical tomography that inverts the Laplace-transformed time-domain coupled diffusion equations and employs a pair of a...We present a full three-dimensional, featured-data algorithm for time-domain fluorescence diffuse optical tomography that inverts the Laplace-transformed time-domain coupled diffusion equations and employs a pair of appropriate transform-factors to effectively separate the fluorescent yield and lifetime parameters. By use of a time-correlation single-photon counting system and the normalized Born formulation, we experimentally validate that the proposed scheme can achieve simultaneous reconstruction of the fluorescent yield and lifetime distributions with a reasonable accuracy.展开更多
The spatial resolution of conventional distributed fiber optic sensors is 1 m at best, which is inadequate to locate the damage precisely. We adopt an improved sensing technique based on the Brillouin optical time-dom...The spatial resolution of conventional distributed fiber optic sensors is 1 m at best, which is inadequate to locate the damage precisely. We adopt an improved sensing technique based on the Brillouin optical time-domain analysis （BOTDA）. The stepped pump light is input to stimulate the phonon so that the spatial resolution can be increased to centimeter order and the strain accuracy of 25 micro-strains is obtained. The feasibility of this sensing technique is demonstrated through strain measurement of three concrete box-girders in bending. Experimental results show that the improved BOTDA measurement can provide a comprehensive description on the strain distribution of steel rebar or concrete. Compared with the conventional strain gauges, the improved BOTDA measurement is more stable. By virtue of higher spatial resolution and better measurement accuracy, it has become possible to perform crack detection and localization for concrete structures.展开更多
We calculate the multicomponent responses of surface-hole transient electromagnetic method. The methods and models are unsuitable as geoelectric models of conductive surrounding rocks because they are based on regular...We calculate the multicomponent responses of surface-hole transient electromagnetic method. The methods and models are unsuitable as geoelectric models of conductive surrounding rocks because they are based on regular local targets. We also propose a calculation and analysis scheme based on numerical simulations of the subsurface transient electromagnetic fields. In the modeling of the electromagnetic fields, the forward modeling simulations are performed by using the finite-difference time-domain method and the discrete image method, which combines the Gaver–Stehfest inverse Laplace transform with the Prony method to solve the initial electromagnetic fields. The precision in the iterative computations is ensured by using the transmission boundary conditions. For the response analysis, we customize geoelectric models consisting of near-borehole targets and conductive wall rocks and implement forward modeling simulations. The observed electric fields are converted into induced electromotive force responses using multicomponent observation devices. By comparing the transient electric fields and multicomponent responses under different conditions, we suggest that the multicomponent-induced electromotive force responses are related to the horizontal and vertical gradient variations of the transient electric field at different times. The characteristics of the response are determined by the varying the subsurface transient electromagnetic fields, i.e., diffusion, attenuation and distortion, under different conditions as well as the electromagnetic fields at the observation positions. The calculation and analysis scheme of the response consider the surrounding rocks and the anomalous field of the local targets. It therefore can account for the geological data better than conventional transient field response analysis of local targets.展开更多
Fluorescence lifetime imaging microscopy(FLIM)is increasingly used in biomedicine,material science,chemistry,and other related research fields,because of its advantages of high specificity and sensitivity in monitorin...Fluorescence lifetime imaging microscopy(FLIM)is increasingly used in biomedicine,material science,chemistry,and other related research fields,because of its advantages of high specificity and sensitivity in monitoring cellular microenvironments,studying interaction between proteins,metabolic state,screening drugs and analyzing their efficacy,characterizing novel materials,and diagnosing early cancers.Understandably,there is a large interest in obtaining FLIM data within an acquisition time as short as possible.Consequently,there is currently a technology that advances towards faster and faster FLIM recording.However,the maximum speed of a recording technique is only part of the problerm.The acquisition time of a FLIM image is a complex function of many factors.These include the photon rate that can be obtained from the sample,the amount of information a technique extracts from the decay functions,the fficiency at which it determines fluorescence decay parameters from the recorded photons,the demands for the accuracy of these parameters,the number of pixels,and the lateral and axial resolutions that are obtained in biological materials.Starting from a discussion of the parameters which determine the acquisition time,this review will describe existing and emerging FLIM techniques and data analysis algo-rithms,and analyze their performance and recording speed in biological and biomedical applications.展开更多
An improved method of generating angle-domain common-image gathers（ADCIGs） by VSP reverse time migration（RTM） is introduced in this paper.The formula which is used to compute the receiver wavefield for VSP RTM is ...An improved method of generating angle-domain common-image gathers（ADCIGs） by VSP reverse time migration（RTM） is introduced in this paper.The formula which is used to compute the receiver wavefield for VSP RTM is modified by adding an amplitude correction term in order to conveniently output amplitude-preserved ADCIGs.Compared with the surface seismic data,VSP data contains much richer wavefields.However,the direct and downgoing waves can bring about serious imaging artifacts in ADCIGs,especially the direct wave.The feasibility and validity of this method is demonstrated by both numerical and real VSP data from western China.Thus,the ADCIGs from this method can provide reliable basic data for VSP migration velocity analysis,VSP AVO/AVA analysis,and inversion.展开更多
提高表面等离子体共振(SPR)阵列检测的灵敏度是蛋白质组学和药物发现与开发的迫切需要。提出了一种基于五步移相时域调制相位干涉成像的变曝光时间图像采集法,通过增大信号幅值来提高光强测量信噪比。在一个相位测量周期的5帧图像中,每...提高表面等离子体共振(SPR)阵列检测的灵敏度是蛋白质组学和药物发现与开发的迫切需要。提出了一种基于五步移相时域调制相位干涉成像的变曝光时间图像采集法,通过增大信号幅值来提高光强测量信噪比。在一个相位测量周期的5帧图像中,每帧图像都采用不同的曝光时间,使得每帧图像的灰度值达到最大,从而提高光强测量的信噪比,保证相位成像检测的高灵敏度。实验结果表明,通过优化电路设计和对CCD致冷控温,自行设计的CCD传感系统的检测灵敏度达到了1.2×10-6RIU(refractive index unit)。在此基础上,采用变曝光时间图像采集法可有效抑制光散粒噪声和CCD读出噪声,将检测灵敏度再提高35%。该方法不仅适用于SPR相位成像检测,而且还可用于其他定步长和等步长相移法以及帧间灰度值变化大的图像采集及相关检测。展开更多
Synthetic aperture imaging ladar （SAIL） technique belongs fully coherent processing in both the time domain and space domain and has a rather high implement difficulty. To solve this problem, the concept of circular...Synthetic aperture imaging ladar （SAIL） technique belongs fully coherent processing in both the time domain and space domain and has a rather high implement difficulty. To solve this problem, the concept of circular incoherently SAIL is introduced. A speckle version image of a two-dimensional （2D） letter ＇E＇ target is reconstructed from E-field projection data detected by a circular incoherently SAIL system. The experimental system is constructed by three subsystems using chirped-pulse laser as the light source and heterodyne detection to get the range information of the target. The reconstruction of the image and the noise effect are also discussed in detail.展开更多
A dynamic range extension scheme applied to a time delay integration （TDI） CMOS image sensor （CIS） is presented. Two types of pixels with higher and lower conversion gain are adopted in the pixel array, which are ...A dynamic range extension scheme applied to a time delay integration （TDI） CMOS image sensor （CIS） is presented. Two types of pixels with higher and lower conversion gain are adopted in the pixel array, which are suitable for capturing images in low and high illumination respectively. By fusing the two kinds of pixels＇ output signals in the process of TDI accumulation, a high dynamic range image can be achieved. Compared with the traditional multiple integration technique, no photoelectrons generated during the exposure time are discarded by the reset operation, and thus a higher level of signal-to-noise ratio （SNR） can be retained. A prototype chip with an 8 × 8 pixel array is implemented in a 0.18 μm CIS process, and the pixel size is 15 × 15 μm2. Test results show that a 76 dB dynamic range can be achieved in 8-stage TDI mode, when the SNR boost can reach 7.26 dB at 90.8 lux.展开更多
Angle-domain common-image gathers （ADCIGs） transformed from the shot- domain common-offset gathers are input to migration velocity analysis （MVA） and prestack inversion. ADCIGs are non-illusion prestack inversion ...Angle-domain common-image gathers （ADCIGs） transformed from the shot- domain common-offset gathers are input to migration velocity analysis （MVA） and prestack inversion. ADCIGs are non-illusion prestack inversion gathers, and thus, accurate. We studied the extraction of elastic-wave ADCIGs based on amplitude-preserving elastic-wave reverse- time migration for calculating the incidence angle of P- and S-waves at each image point and for different source locations. The P- and S-waves share the same incident angle, namely the incident angle of the source P-waves. The angle of incidence of the source P-wavefield was the difference between the source P-wave propagation angle and the reflector dips. The propagation angle of the source P-waves was obtained from the polarization vector of the decomposed P-waves. The reflectors＇ normal direction angle was obtained using the complex wavenumber of the stacked reverse-time migration （RTM） images. The ADCIGs of P- and S-waves were obtained by rearranging the common-shot migration gathers based on the incident angle. We used a horizontally layered model, the graben medium model, and part of the Marmousi-II elastic model and field data to test the proposed algorithm. The results suggested that the proposed method can efficiently extract the P- and S-wave ADCIGs of the elastic-wave reverse-time migration, the P- and S-wave incident angle, and the angle-gather amplitude fidelity, and improve the MVA and prestack inversion.展开更多
基金supported by the National Natural Science Foundation of China(No.60578008,60678049)the National Basic Research Program of China(No.2006CB705700)Tianjin Municipal Government of China(No.07JCYBJC06600)
文摘We present a full three-dimensional, featured-data algorithm for time-domain fluorescence diffuse optical tomography that inverts the Laplace-transformed time-domain coupled diffusion equations and employs a pair of appropriate transform-factors to effectively separate the fluorescent yield and lifetime parameters. By use of a time-correlation single-photon counting system and the normalized Born formulation, we experimentally validate that the proposed scheme can achieve simultaneous reconstruction of the fluorescent yield and lifetime distributions with a reasonable accuracy.
基金supported by the National Natural Science Foundation of China (Nos.50725828 and 50608017)the Sustentation Fund for Young Teachers of Southeast University
文摘The spatial resolution of conventional distributed fiber optic sensors is 1 m at best, which is inadequate to locate the damage precisely. We adopt an improved sensing technique based on the Brillouin optical time-domain analysis （BOTDA）. The stepped pump light is input to stimulate the phonon so that the spatial resolution can be increased to centimeter order and the strain accuracy of 25 micro-strains is obtained. The feasibility of this sensing technique is demonstrated through strain measurement of three concrete box-girders in bending. Experimental results show that the improved BOTDA measurement can provide a comprehensive description on the strain distribution of steel rebar or concrete. Compared with the conventional strain gauges, the improved BOTDA measurement is more stable. By virtue of higher spatial resolution and better measurement accuracy, it has become possible to perform crack detection and localization for concrete structures.
基金supported by the Young Scientists Fund of the National Natural Science Foundation of China(No.41304082)the China Postdoctoral Science Foundation(No.2016M590731)+2 种基金the Young Scientists Fund of the Natural Science Foundation of Hebei Province(No.D2014403011)the Program for Young Excellent Talents of Higher Education Institutions of Hebei Province(No.BJ2016046)the Geological survey project of China Geological Survey(No.1212011121197)
文摘We calculate the multicomponent responses of surface-hole transient electromagnetic method. The methods and models are unsuitable as geoelectric models of conductive surrounding rocks because they are based on regular local targets. We also propose a calculation and analysis scheme based on numerical simulations of the subsurface transient electromagnetic fields. In the modeling of the electromagnetic fields, the forward modeling simulations are performed by using the finite-difference time-domain method and the discrete image method, which combines the Gaver–Stehfest inverse Laplace transform with the Prony method to solve the initial electromagnetic fields. The precision in the iterative computations is ensured by using the transmission boundary conditions. For the response analysis, we customize geoelectric models consisting of near-borehole targets and conductive wall rocks and implement forward modeling simulations. The observed electric fields are converted into induced electromotive force responses using multicomponent observation devices. By comparing the transient electric fields and multicomponent responses under different conditions, we suggest that the multicomponent-induced electromotive force responses are related to the horizontal and vertical gradient variations of the transient electric field at different times. The characteristics of the response are determined by the varying the subsurface transient electromagnetic fields, i.e., diffusion, attenuation and distortion, under different conditions as well as the electromagnetic fields at the observation positions. The calculation and analysis scheme of the response consider the surrounding rocks and the anomalous field of the local targets. It therefore can account for the geological data better than conventional transient field response analysis of local targets.
基金support from the National Key R&D Program of China(2017YFA0700500)National Natural Science Foundation of China(61775144/61525503/61620106016/61835009/81727804)+2 种基金(Key)Project of Department of Education of Guangdong Province(2015KGJHZ002/2016KCXTD007)Guangdong Natural Science Foundation(2014A030312008,2017A030310132,2018A030313362)Shenzhen Basic Research Project(JCYJ20170818144012025/JCYJ20170818141701667/JCYJ20170412105003520/JCYJ20150930104948169).
文摘Fluorescence lifetime imaging microscopy(FLIM)is increasingly used in biomedicine,material science,chemistry,and other related research fields,because of its advantages of high specificity and sensitivity in monitoring cellular microenvironments,studying interaction between proteins,metabolic state,screening drugs and analyzing their efficacy,characterizing novel materials,and diagnosing early cancers.Understandably,there is a large interest in obtaining FLIM data within an acquisition time as short as possible.Consequently,there is currently a technology that advances towards faster and faster FLIM recording.However,the maximum speed of a recording technique is only part of the problerm.The acquisition time of a FLIM image is a complex function of many factors.These include the photon rate that can be obtained from the sample,the amount of information a technique extracts from the decay functions,the fficiency at which it determines fluorescence decay parameters from the recorded photons,the demands for the accuracy of these parameters,the number of pixels,and the lateral and axial resolutions that are obtained in biological materials.Starting from a discussion of the parameters which determine the acquisition time,this review will describe existing and emerging FLIM techniques and data analysis algo-rithms,and analyze their performance and recording speed in biological and biomedical applications.
基金supported by National Basic Research Program of China (No. 2011CB201100)National Department of Science and Technology (No. 2008ZX05004-006)
文摘An improved method of generating angle-domain common-image gathers（ADCIGs） by VSP reverse time migration（RTM） is introduced in this paper.The formula which is used to compute the receiver wavefield for VSP RTM is modified by adding an amplitude correction term in order to conveniently output amplitude-preserved ADCIGs.Compared with the surface seismic data,VSP data contains much richer wavefields.However,the direct and downgoing waves can bring about serious imaging artifacts in ADCIGs,especially the direct wave.The feasibility and validity of this method is demonstrated by both numerical and real VSP data from western China.Thus,the ADCIGs from this method can provide reliable basic data for VSP migration velocity analysis,VSP AVO/AVA analysis,and inversion.
文摘提高表面等离子体共振(SPR)阵列检测的灵敏度是蛋白质组学和药物发现与开发的迫切需要。提出了一种基于五步移相时域调制相位干涉成像的变曝光时间图像采集法,通过增大信号幅值来提高光强测量信噪比。在一个相位测量周期的5帧图像中,每帧图像都采用不同的曝光时间,使得每帧图像的灰度值达到最大,从而提高光强测量的信噪比,保证相位成像检测的高灵敏度。实验结果表明,通过优化电路设计和对CCD致冷控温,自行设计的CCD传感系统的检测灵敏度达到了1.2×10-6RIU(refractive index unit)。在此基础上,采用变曝光时间图像采集法可有效抑制光散粒噪声和CCD读出噪声,将检测灵敏度再提高35%。该方法不仅适用于SPR相位成像检测,而且还可用于其他定步长和等步长相移法以及帧间灰度值变化大的图像采集及相关检测。
基金supported by the Key Laboratory of Space Laser Communication and Testing Technology of the Chinese Academy of Sciences and the National Nature Science Foundation of China (No. 61108069)
文摘Synthetic aperture imaging ladar （SAIL） technique belongs fully coherent processing in both the time domain and space domain and has a rather high implement difficulty. To solve this problem, the concept of circular incoherently SAIL is introduced. A speckle version image of a two-dimensional （2D） letter ＇E＇ target is reconstructed from E-field projection data detected by a circular incoherently SAIL system. The experimental system is constructed by three subsystems using chirped-pulse laser as the light source and heterodyne detection to get the range information of the target. The reconstruction of the image and the noise effect are also discussed in detail.
基金Project supported by the National Natural Science Foundation of China(Nos.61036004,61076024)
文摘A dynamic range extension scheme applied to a time delay integration （TDI） CMOS image sensor （CIS） is presented. Two types of pixels with higher and lower conversion gain are adopted in the pixel array, which are suitable for capturing images in low and high illumination respectively. By fusing the two kinds of pixels＇ output signals in the process of TDI accumulation, a high dynamic range image can be achieved. Compared with the traditional multiple integration technique, no photoelectrons generated during the exposure time are discarded by the reset operation, and thus a higher level of signal-to-noise ratio （SNR） can be retained. A prototype chip with an 8 × 8 pixel array is implemented in a 0.18 μm CIS process, and the pixel size is 15 × 15 μm2. Test results show that a 76 dB dynamic range can be achieved in 8-stage TDI mode, when the SNR boost can reach 7.26 dB at 90.8 lux.
基金supported by Financially Supported by Qingdao National Laboratory for Marine Science and Technology(No.QNLM2016ORP0206)National Science and Technology Major Project(No.2016ZX05027-002)+6 种基金China Postdoctoral Science Foundation(No.2017M612219)National Key R&D Plan(Nos.2017YFC0306706 and 2017YFC0307400)Financially Supported by Qingdao National Laboratory for Marine Science and Technology(No.QNLM201708)Natural Science Foundation of Shandong Province(No.ZR2016DB10)National Natural Science Foundation of China(Nos.41674118,41504109,and 41506084)Key Laboratory of Submarine Geosciences Foundation of SOA(No.KLSG1603)Qingdao Municipal Applied Research Projects(No.2016238)
文摘Angle-domain common-image gathers （ADCIGs） transformed from the shot- domain common-offset gathers are input to migration velocity analysis （MVA） and prestack inversion. ADCIGs are non-illusion prestack inversion gathers, and thus, accurate. We studied the extraction of elastic-wave ADCIGs based on amplitude-preserving elastic-wave reverse- time migration for calculating the incidence angle of P- and S-waves at each image point and for different source locations. The P- and S-waves share the same incident angle, namely the incident angle of the source P-waves. The angle of incidence of the source P-wavefield was the difference between the source P-wave propagation angle and the reflector dips. The propagation angle of the source P-waves was obtained from the polarization vector of the decomposed P-waves. The reflectors＇ normal direction angle was obtained using the complex wavenumber of the stacked reverse-time migration （RTM） images. The ADCIGs of P- and S-waves were obtained by rearranging the common-shot migration gathers based on the incident angle. We used a horizontally layered model, the graben medium model, and part of the Marmousi-II elastic model and field data to test the proposed algorithm. The results suggested that the proposed method can efficiently extract the P- and S-wave ADCIGs of the elastic-wave reverse-time migration, the P- and S-wave incident angle, and the angle-gather amplitude fidelity, and improve the MVA and prestack inversion.
