Borehole acoustic reflection logging can provide high resolution images of nearborehole geological structure. However, the conventional seismic migration and imaging methods are not effective because the reflected wav...Borehole acoustic reflection logging can provide high resolution images of nearborehole geological structure. However, the conventional seismic migration and imaging methods are not effective because the reflected waves are interfered with the dominant borehole-guided modes and there are only eight receiving channels per shot available for stacking. In this paper, we apply an equivalent offset migration method based on wave scattering theory to process the acoustic reflection imaging log data from both numerical modeling and recorded field data. The result shows that, compared with the routine post-stack depth migration method, the equivalent offset migration method results in higher stack fold and is more effective for near-borehole structural imaging with low SNR acoustic reflection log data.展开更多
Structured-illumination reflectance imaging(SIRI)provides a new means for food quality detection.This original work investigated the capability of(SIRI)technique coupled with multivariate chemometrics to evaluate the ...Structured-illumination reflectance imaging(SIRI)provides a new means for food quality detection.This original work investigated the capability of(SIRI)technique coupled with multivariate chemometrics to evaluate the microbial contamination in pork inoculated with Pseudomonas fluorescens and Brochothrix thermosphacta during storage at different temperatures.The prediction performances based on different spectrum and the textural features of direct component and amplitude component images demodulated from the SIRI pattern,as well as their data fusion were comprehensively compared.Based on the full wavelength spectrum(420-700 nm)of amplitude component images,the orthogonal signal correction coupled with support vector machine regression provided the best predictions of the number of P.fluorescens and B.thermosphacta in pork,with the determination coefficients of prediction(R_(p)^(2))values of 0.870 and 0.906,respectively.Besides,the prediction models based on the amplitude component or direct component image textural features and the data fusion models using spectrum and textural features from direct component and amplitude component images cannot significantly improve their prediction accuracy.Consequently,SIRI can be further considered as a potential technique for the rapid evaluation of microbial contaminations in pork meat.展开更多
The numerical dispersion phenomenon in the finite-difference forward modeling simulations of the wave equation significantly affects the imaging accuracy in acoustic reflection logging.This issue is particularly prono...The numerical dispersion phenomenon in the finite-difference forward modeling simulations of the wave equation significantly affects the imaging accuracy in acoustic reflection logging.This issue is particularly pronounced in the reverse time migration(RTM)method used for shear-wave(S-wave)logging imaging.This not only affects imaging accuracy but also introduces ambiguities in the interpretation of logging results.To address this challenge,this study proposes the use of a least-squares difference coefficient optimization algorithm aiming to suppress the numerical dispersion phenomenon in the RTM of S-wave reflection imaging logging.By optimizing the difference coefficients,the high-precision finite-difference algorithm serves as an effective operator for both forward and backward RTM processes.This approach is instrumental in eliminating migration illusions,which are often caused by numerical dispersion.The effectiveness of this optimized algorithm is demonstrated through numerical results,which indicate that it can achieve more accurate forward imaging results across various conditions,including high-and low-velocity strata,and is effective in both large and small spatial grids.The results of processing real data demonstrate that numerical dispersion optimization effectively reduces migration artifacts and diminishes ambiguities in logging interpretations.This optimization offers crucial technical support to the RTM method,enhancing its capability for accurately modeling and imaging S-wave reflections.展开更多
Acoustic reflection imaging logging technology can detect and evaluate the development of reflection anomalies,such as fractures,caves and faults,within a range of tens of meters from the wellbore,greatly expanding th...Acoustic reflection imaging logging technology can detect and evaluate the development of reflection anomalies,such as fractures,caves and faults,within a range of tens of meters from the wellbore,greatly expanding the application scope of well logging technology.This article reviews the development history of the technology and focuses on introducing key methods,software,and on-site applications of acoustic reflection imaging logging technology.Based on the analyses of major challenges faced by existing technologies,and in conjunction with the practical production requirements of oilfields,the further development directions of acoustic reflection imaging logging are proposed.Following the current approach that utilizes the reflection coefficients,derived from the computation of acoustic slowness and density,to perform seismic inversion constrained by well logging,the next frontier is to directly establish the forward and inverse relationships between the downhole measured reflection waves and the surface seismic reflection waves.It is essential to advance research in imaging of fractures within shale reservoirs,the assessment of hydraulic fracturing effectiveness,the study of geosteering while drilling,and the innovation in instruments of acoustic reflection imaging logging technology.展开更多
To solve problems in small-scale and complex structural traps,the inverse Gaussian-beam stack-imaging method is commonly used to process crosswell seismic wave reflection data.Owing to limited coverage,the imaging qua...To solve problems in small-scale and complex structural traps,the inverse Gaussian-beam stack-imaging method is commonly used to process crosswell seismic wave reflection data.Owing to limited coverage,the imaging quality of conventional ray-based crosswell seismic stack imaging is poor in complex areas;moreover,the imaging range is small and with sever interference because of the arc phenomenon in seismic migration.Thus,we propose the inverse Gaussian-beam stack imaging,in which Gaussian weight functions of rays contributing to the geophones energy are calculated and used to decompose the seismic wavefield.This effectively enlarges the coverage of the reflection points and improves the transverse resolution.Compared with the traditional VSP–CDP stack imaging,the proposed methods extends the imaging range,yields higher horizontal resolution,and is more adaptable to complex geological structures.The method is applied to model a complex structure in the K-area.The results suggest that the wave group of the target layer is clearer,the resolution is higher,and the main frequency of the crosswell seismic section is higher than that in surface seismic exploration The effectiveness and robustness of the method are verified by theoretical model and practical data.展开更多
I present results of processing and structural interpretation of narrow-angle seismic reflection data recorded over an area of 30 × 50 km located in the southern part of the North Apuseni Mts, Romania. The invest...I present results of processing and structural interpretation of narrow-angle seismic reflection data recorded over an area of 30 × 50 km located in the southern part of the North Apuseni Mts, Romania. The investigated area is characterized by complex subsurface geology and rough topography. The seismic measurements were performed along five linear profiles, P1-P5, using an active spread of 96 geophones for each shot point;geophone spacing was 25 m. The length of each acquisition line is greater than 10 km. The signal-to-noise ratio of these data varies along the lines and its variation is considered to be an effect of rough topography, complex subsurface geology and varying surface conditions encountered during seismic data acquisition. The data processing was performed using a standard processing flow but with different processing parameters from one data set to another. I obtained five depth-converted migrated seismic sections after data processing. The accuracy of the depth values depends on that of the stacking velocities obtained from the velocity analyses performed on the filtered seismic data. Borehole information is not available, the investigated area belonging to the areas investigated for hydrocarbons. Each seismic section shows a different structural image of the subsurface and provides useful information about the tectonic and stratigraphic evolution of the investigated area. I obtained various structural images of the subsurface after the interpretation of the depth-converted migrated seismic sections, from a simple one with undeformed and inclined reflectors to a complex one with folded and faulted reflectors, especially the older ones. I interpreted intrusive bodies piercing through the overlying sediments, which are in good agreement with the results of older geophysical studies.展开更多
Adhesion molecule CD146(100-130kDa)belongs to the immunoglobulin super family and it is originally identified as a biomarker for melanoma.Recently,CD146 is found as novel target molecule on endothelial cell and involv...Adhesion molecule CD146(100-130kDa)belongs to the immunoglobulin super family and it is originally identified as a biomarker for melanoma.Recently,CD146 is found as novel target molecule on endothelial cell and involved in tumor angiogenesis.Also CD146 is considered as critical molecule in cell invasion and anti-CD146 antibody could inhibit tumor metastasis and angiogenesis through its down regulation of NFk.In this report,we study the quantitative detection of the CD146 molecule in positive serum with the TIRIE biosensor.展开更多
The purpose of this study is to evaluate the Spectral Angle Mapper （SAM） classification method for determining the optimum threshold （maximum spectral angle） to unveil the hydrothermal mineral assemblages related ...The purpose of this study is to evaluate the Spectral Angle Mapper （SAM） classification method for determining the optimum threshold （maximum spectral angle） to unveil the hydrothermal mineral assemblages related to mineral deposits. The study area indicates good potential for Cu-Au porphyry, epithermal gold deposits and hydrothermal alteration well developed in arid and semiarid climates, which makes this region significant for Advanced Spaceborne Thermal Emission and Reflection Radiometer （ASTER） image processing analysis. Given that achieving an acceptable mineral mapping requires knowing the alteration patterns, petrochemistry and petrogenesis of the igneous rocks while considering the effect of weathering, overprinting of supergene alteration, overprinting of hypogene alteration and host rock spectral mixing, SAM classification was implemented for argillic, sericitic, propylitic, alunitization, silicification and iron oxide zones of six previously known mineral deposits： Maherabad, a Cu-Au porphyry system; Sheikhabad, an upper part of Cu-Au porphyry system; Khoonik, an Intrusion related Au system; Barmazid, a low sulfidation epithermal system; Khopik, a Cu-Au porphyry system; and Hanish, an epithermal Au system. Thus, the investigation showed that although the whole alteration zones are affected by mixing, it is also possible to produce a favorable hydrothermal mineral map by such complementary data as petrology, petrochemistry and alteration patterns.展开更多
The safety accidents caused by collapse column water diversion occur frequently, which has great hidden danger to the safety production of coal mine. Limited by the space of underground, the detection of collapse colu...The safety accidents caused by collapse column water diversion occur frequently, which has great hidden danger to the safety production of coal mine. Limited by the space of underground, the detection of collapse column on the outside of working face has been a difficult problem. Based on this, numerical simulation and imaging research were carried out in this paper. The results indicate that when a seismic source near the roadway is excited, a part of seismic wave propagates along the roadway direction, namely direct P-wave, direct S-wave and direct Love channel wave.<span style="font-family:;" "=""> <span style="font-family:Verdana;">When the body waves and Love channel wave propagating to the outside<span style="font-family:;" "=""> <span style="font-family:Verdana;">of working face meet the interface of collapse column, the reflected Love channel wave and reflected body waves are generated.<span style="font-family:;" "=""> <span style="font-family:Verdana;">Reflection <span style="font-family:Verdana;">body <span style="font-family:Verdana;">waves and direct waves are mixed in time domain, which is difficult to identify in seismic records, while reflected Love channel wave whose amplitude is relatively strong. The <span style="font-family:Verdana;">reflected <span style="font-family:Verdana;">Love channel wave which has a large interval from other wave trains in the time domain is easily recognizable in seismic record,<span style="font-family:;" "=""> <span style="font-family:Verdana;">which<span style="font-family:;" "=""> <span style="font-family:Verdana;">makes it suitable for advanced detection of collapse column. The signal-to-noise ratio of X component is higher than that of Y component and Z component. According to the seismic records, polarization filtering was carried out to enhance the effective wave, which removed the interference waves, and the signal was migrated to get the position parameters of collapse column interface, which was basically consistent with the model position.展开更多
To identify coatings and analyze the anti-detection capabilities of camouflage patterns, material samples can be prepared using the super-pixel segmentation method. A spectral polarization imaging system is developed,...To identify coatings and analyze the anti-detection capabilities of camouflage patterns, material samples can be prepared using the super-pixel segmentation method. A spectral polarization imaging system is developed, based on the principle of bidirectional reflectance distribution function(BRDF), to obtain spectral reflection intensities of coatings at full spatial angles, and use polarization images to calculate the refractive index by the Fresnel equation. The index is then coupled into TorranceSparrow model to simulate the spectral scattering intensity to mutually verify the experimental results. The spectral scattering characteristics of standard camouflage patterns are then revealed and pinpoint the signature band and the angle of reflecting sensitivity.展开更多
The vibration is one of the important factors affecting imaging quality of conventional remote sensing imaging because the relative motion between the imaging system and the target can result in the degradation of ima...The vibration is one of the important factors affecting imaging quality of conventional remote sensing imaging because the relative motion between the imaging system and the target can result in the degradation of imaging quality. The influence of the vibration of the detector in the test path on reflective ghost imaging （RGI） is investigated theoretically and experimentally. We analyze the effects of the vibrating amplitude and velocity. The results demonstrate that the microvibrations of the bucket detector have almost no impact on the imaging resolution and signal-to-noise ratio （SNR） of RGI, i.e., the degradation of imaging quality caused by the vibration of the detector can be overcome to some extent. Our results can be helpful for remote sensing imaging.展开更多
In recent years,there has been a backlash of sorts and the authenticity of images has been routinely questioned.Seeing is no longer believing.There is an urgent need for robust image forensic techniques to expose phot...In recent years,there has been a backlash of sorts and the authenticity of images has been routinely questioned.Seeing is no longer believing.There is an urgent need for robust image forensic techniques to expose photo forgery.This paper proposed a novel and effective technique to expose image forgery using inconsistent reflection.More specifically,a new technique was presented to calculate reflection line midpoint,the definition of midpoint ratio was given,and three standards were proposed and employed to detect image forgery.Accuracy and effectiveness of the proposed technique were evaluated using a data set consisting of 200 authentic and forged images.Experimental results indicate that the proposed method can detect image forgery with very high success rate.展开更多
Sand dust belts span approximately one-fifth of the global land surface.In these regions,dust tends to settle on vegetation surfaces,altering the observed reflectance and affecting remote sensing detections.To enhance...Sand dust belts span approximately one-fifth of the global land surface.In these regions,dust tends to settle on vegetation surfaces,altering the observed reflectance and affecting remote sensing detections.To enhance the accuracy of maize growth monitoring in dust-affected regions,this study aims to quantify the effect of sand dust retention on maize during the tasseling stage in the Kashgar Prefecture,Xinjiang Uygur Autonomous Region,China,by analyzing changes in canopy reflectance and vegetation indices.First,field sampling was conducted to measure the key canopy structure parameters and dust retention levels of maize,and laboratory spectral measurements were performed on leaf spectral properties under gradient dust retention.The measured data were then used to drive the LargE-Scale remote sensing data and image Simulation framework(LESS)model for simulating realistic maize canopy spectra across different dust levels,with validation against Sentinel-2 imagery.Second,on the basis of the simulated and satellite-derived spectra,the dust resistance of 36 common vegetation indices was systematically evaluated,and new robust dust-resistant indices were developed.The results showed that compared with dust-free maize,the canopy reflectance of dust-retained maize followed an increase–decrease–increase pattern,with critical turning points at 735 and 1325 nm.The maximum reflectance difference of–0.11755(change rate:29.002%)occurred within the 735–1325 nm range at 24 g/m^(2)dust retention,and the minimum reflectance difference of 0.04285(change rate:148.950%)was observed in the 350–735 nm range under the same dust retention level.Among the 36 vegetation indices,only the global environment monitoring index(GEMI)and the ratio of transformed chlorophyll absorption in reflectance index to optimized soil-adjusted vegetation index(TCARI/OSAVI)exhibited dust resistance,with GEMI being effective below 6 g/m^(2)and TCARI/OSAVI remaining stable across all levels(average ratio:0.970).The newly developed indices in this study,(RE3–RE2)/(NIR–RE2),(RE3–RE2)/(RE4–RE2),and(NIR–RE2)/(RE4–RE2),retained values within the predefined dust-resistant range over the full dust retention levels of 0–24 g/m^(2),thus showing a more stable dust resistance compared with the commonly used 36 vegetation indices.Specially,(RE3–RE2)/(RE4–RE2)performed the most robustly in Sentinel-2 imagery,that is,58.020%of pixels were within the dust-resistant range,and an average ratio of 0.937 was obtained for the original-spectra index.This study provides a scientific basis for crop monitoring and management in dust-affected regions.展开更多
Fracture identification is important for the evaluation of carbonate reservoirs. However, conventional logging equipment has small depth of investigation and cannot detect rock fractures more than three meters away fr...Fracture identification is important for the evaluation of carbonate reservoirs. However, conventional logging equipment has small depth of investigation and cannot detect rock fractures more than three meters away from the borehole. Remote acoustic logging uses phase-controlled array-transmitting and long sound probes that increase the depth of investigation. The interpretation of logging data with respect to fractures is typically guided by practical experience rather than theory and is often ambiguous. We use remote acoustic reflection logging data and high-order finite-difference approximations in the forward modeling and prestack reverse-time migration to image fractures. First, we perform forward modeling of the fracture responses as a function of the fracture-borehole wall distance, aperture, and dip angle. Second, we extract the energy intensity within the imaging area to determine whether the fracture can be identified as the formation velocity is varied. Finally, we evaluate the effect of the fracture-borehole distance, fracture aperture, and dip angle on fracture identification.展开更多
One of the problems experienced in marine geophysical exploration is that the layered features in the migration imaging profile are blurred and the seismic energy reflected is weaker in the middle or lower parts. In t...One of the problems experienced in marine geophysical exploration is that the layered features in the migration imaging profile are blurred and the seismic energy reflected is weaker in the middle or lower parts. In this study we model the seismic wavefield records in the undulating seafloor when there is both a slight change and significant change in seafloor topography to analyze its influence on the seismic reflection data and migration imaging profiles. We compare and analyze the wave field records collected at the same point on the original and modified velocity models, and the cross-bonding resulting migration imaging profiles. The results show that whether the seismic reflection data collection is performed along the direction of the survey line or against the direction of the survey line, slight changes in the seafloor topography have little effect on the wave field records and the migration profile, while significant changes in the seafloor topography have great effect on both the wave field records and migration profile.展开更多
High-resolution seismic reflections have been used effectively to investigate sinkholes formed from the dissolution of a bedded salt unit found throughout most of Central Kansas. Surface subsidence can have devastatin...High-resolution seismic reflections have been used effectively to investigate sinkholes formed from the dissolution of a bedded salt unit found throughout most of Central Kansas. Surface subsidence can have devastating effects on transportation structures. Roads, rails, bridges, and pipelines can even be dramatically affected by minor ground instability. Areas susceptible to surface subsidence can put public safety at risk. Subsurface expressions significantly larger than surface depressions are consistently observed on seismic images recorded over sinkholes in Kansas. Until subsidence reaches the ground surface, failure appears to be controlled by compressional forces evidenced by faults with reverse orientation. Once a surface depression forms or dissolution of the salt slows or stops, subsidence structures are consistent with a tensional stress environment with prevalent normal faults. Detecting areas of rapid subsidence potential, prior to surface failure, is the ultimate goal of any geotechnical survey where the ground surface is susceptible to settling. Seismic reflection images have helped correlate active subsidence to dormant paleofeatures, project horizontal growth of active sinkholes based on subsurface structures, and appraise the risk of catastrophic failure.展开更多
Objective:We applied hyperspectral imaging(HSI)system to distinguish early caries from soundand pigmented areas.It will provide a theoretical basis and technical support,for research anddevelopment of an instrument th...Objective:We applied hyperspectral imaging(HSI)system to distinguish early caries from soundand pigmented areas.It will provide a theoretical basis and technical support,for research anddevelopment of an instrument that could be used for screening and detection of early dentalcaries.Methods:Eighteen extracted human teeth(molars and premolars),with varying degrees ofnatural pathology and no degree of decay involving dentin were obtained.HSI system with awavelength range from 400 to 1000nm was used to obtain images of all 18 teeth containingsound,carious and pigmented areas.We compared the spectra of the wavebands at both 500 nmand 780 nm from the different tooth states,and the reflectance diference bet ween sound versuscarious lesions and sound versus pigmented areas,respectively.Results:There was a slight diference in refectance bet ween carious areas and pigmented areas at500 nm.A substantial difference was additionally noted in refectance bet ween carious areas andpigmented areas at 780 nm.Conclusion:The results have shown that the interference of tooth surface pigment can be elim-inated in the near-infrared(NIR)waveband,and the caries can be effectively identifed from the pigmented areas.Thus,it could be used to detect carious areas of teeth in place of the traditionalvisual inspection method or white light endoscopy.Clinical significance:The NIR difused light signal enables the identification of early caries frompigment and other interference,providing a reasonable detection tool for early detection andearly treatment of teeth diseases.展开更多
High ultraviolet(UV)stability and low dark current(Idark)are necessary for high-quality perovskite photodetectors(PDs).TiO^(2)thin film is known as effective electron-transport-layer(ETL)for perovskite devices.However...High ultraviolet(UV)stability and low dark current(Idark)are necessary for high-quality perovskite photodetectors(PDs).TiO^(2)thin film is known as effective electron-transport-layer(ETL)for perovskite devices.However,common spin-coated TiO^(2)ETLs endow many surface defects and have strong UV photocatalytic effect to decompose perovskite materials,resulting in inferior stability of devices.In this work,TiO^(2)bilayer film(Bi-TiO^(2))has been fabricated by combining spin-coating and atomic-layer-deposition process and its positive effects on UV stability and Idarkof Cs2 AgBiBr6-based PDs have been revealed for the first time.It is demonstrated that Bi-TiO^(2)possesses fewer surface defects and smoother morphology with type II band alignment,which is beneficial to suppress photocatalytic activity of TiO^(2)and reduce carrier recombination at the interface.After accelerated strong UV aging treatment,the PD with Bi-TiO^(2)maintains excellent performance,whereas the PD with spin-coated TiO^(2)film dramatically deteriorate with on-off ratio drops from~102 to~2.Besides,the Idarkof PD remarkably decreases from~10^(-8) A to~10^(-10) A after bilayer optimization.Furthermore,we have integrated the corresponding PDs into a self-built imaging system adopting diffuse reflection mode.This work suggests a feasible approach to fabricate TiO^(2)/Cs2 AgBiBr6-based PDs with remarkable UV tolerance for imaging applications.展开更多
The rapid development of image processing techniques has made it extremely easy to alter the content of images or create newimages.So photographs,which appear in magazines,social media,and political attacks,can no lon...The rapid development of image processing techniques has made it extremely easy to alter the content of images or create newimages.So photographs,which appear in magazines,social media,and political attacks,can no longer be trusted.A novel and effective technique is proposed in this paper to expose image forgery using inconsistent reflection vanishing point(RVP).More specifically,the definition of error distance is given,sin^2()-based function is proposed to normalize error distance,and a reasonable threshold value is set to detect image forgery.The experimental data and results are presented to demonstrate the accuracy and effectiveness of the technique.展开更多
This paper gives the relation between spatial ray and its projection on paper plane based on the vector form of reflective law. Using the method of prism expansion, it obtains the exact expression of the exit height. ...This paper gives the relation between spatial ray and its projection on paper plane based on the vector form of reflective law. Using the method of prism expansion, it obtains the exact expression of the exit height. The exit height can ensure that the incident rays, at arbitrary direction and arbitrary angle, after several transmission and reflection in the two right-angle reflectors, finally pass through the exit surface. Furthermore, it analyses the effects of different parameters on the exit height through computer simulation, and some important conclusions are obtained. The physical meaning of the sign of exit height is described, and the exact expression of the minimal thickness of the large optical path difference wind imaging interferometer is gained. This work is of great scientific significance to the static, real- time simultaneous detection of atmospheric wind field, and it will provide a theoretical and practical guidance for the miniaturization design and engineering realization of wind imaging interferometer.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.50674098)the 863 Program (Grant No.2006AA06Z207 & 2006AA06Z213)the 973 Program (Grant No.2007CB209601)
文摘Borehole acoustic reflection logging can provide high resolution images of nearborehole geological structure. However, the conventional seismic migration and imaging methods are not effective because the reflected waves are interfered with the dominant borehole-guided modes and there are only eight receiving channels per shot available for stacking. In this paper, we apply an equivalent offset migration method based on wave scattering theory to process the acoustic reflection imaging log data from both numerical modeling and recorded field data. The result shows that, compared with the routine post-stack depth migration method, the equivalent offset migration method results in higher stack fold and is more effective for near-borehole structural imaging with low SNR acoustic reflection log data.
基金supported by Key Research&Development Program of Jiangsu Province in China(BE2020693)Major Project of Science and Technology of Anhui Province(201903a06020010)+1 种基金Joint Key Project of Science and Technology Innovation of Yangtze River Delta in Anhui Province(202004g01020009)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘Structured-illumination reflectance imaging(SIRI)provides a new means for food quality detection.This original work investigated the capability of(SIRI)technique coupled with multivariate chemometrics to evaluate the microbial contamination in pork inoculated with Pseudomonas fluorescens and Brochothrix thermosphacta during storage at different temperatures.The prediction performances based on different spectrum and the textural features of direct component and amplitude component images demodulated from the SIRI pattern,as well as their data fusion were comprehensively compared.Based on the full wavelength spectrum(420-700 nm)of amplitude component images,the orthogonal signal correction coupled with support vector machine regression provided the best predictions of the number of P.fluorescens and B.thermosphacta in pork,with the determination coefficients of prediction(R_(p)^(2))values of 0.870 and 0.906,respectively.Besides,the prediction models based on the amplitude component or direct component image textural features and the data fusion models using spectrum and textural features from direct component and amplitude component images cannot significantly improve their prediction accuracy.Consequently,SIRI can be further considered as a potential technique for the rapid evaluation of microbial contaminations in pork meat.
基金supported by Scientific Research and Technology Development Project of CNPC(2021DJ4002,2022DJ3908).
文摘The numerical dispersion phenomenon in the finite-difference forward modeling simulations of the wave equation significantly affects the imaging accuracy in acoustic reflection logging.This issue is particularly pronounced in the reverse time migration(RTM)method used for shear-wave(S-wave)logging imaging.This not only affects imaging accuracy but also introduces ambiguities in the interpretation of logging results.To address this challenge,this study proposes the use of a least-squares difference coefficient optimization algorithm aiming to suppress the numerical dispersion phenomenon in the RTM of S-wave reflection imaging logging.By optimizing the difference coefficients,the high-precision finite-difference algorithm serves as an effective operator for both forward and backward RTM processes.This approach is instrumental in eliminating migration illusions,which are often caused by numerical dispersion.The effectiveness of this optimized algorithm is demonstrated through numerical results,which indicate that it can achieve more accurate forward imaging results across various conditions,including high-and low-velocity strata,and is effective in both large and small spatial grids.The results of processing real data demonstrate that numerical dispersion optimization effectively reduces migration artifacts and diminishes ambiguities in logging interpretations.This optimization offers crucial technical support to the RTM method,enhancing its capability for accurately modeling and imaging S-wave reflections.
基金Supported by the PetroChina Science and Technology Project(2021DJ4002,2022DJ3908)。
文摘Acoustic reflection imaging logging technology can detect and evaluate the development of reflection anomalies,such as fractures,caves and faults,within a range of tens of meters from the wellbore,greatly expanding the application scope of well logging technology.This article reviews the development history of the technology and focuses on introducing key methods,software,and on-site applications of acoustic reflection imaging logging technology.Based on the analyses of major challenges faced by existing technologies,and in conjunction with the practical production requirements of oilfields,the further development directions of acoustic reflection imaging logging are proposed.Following the current approach that utilizes the reflection coefficients,derived from the computation of acoustic slowness and density,to perform seismic inversion constrained by well logging,the next frontier is to directly establish the forward and inverse relationships between the downhole measured reflection waves and the surface seismic reflection waves.It is essential to advance research in imaging of fractures within shale reservoirs,the assessment of hydraulic fracturing effectiveness,the study of geosteering while drilling,and the innovation in instruments of acoustic reflection imaging logging technology.
基金sponsored by the National Key R&D Plan Project(Grant No.2016YFC0303900)Natural Science Foundation of China(Grant No.41374145)
文摘To solve problems in small-scale and complex structural traps,the inverse Gaussian-beam stack-imaging method is commonly used to process crosswell seismic wave reflection data.Owing to limited coverage,the imaging quality of conventional ray-based crosswell seismic stack imaging is poor in complex areas;moreover,the imaging range is small and with sever interference because of the arc phenomenon in seismic migration.Thus,we propose the inverse Gaussian-beam stack imaging,in which Gaussian weight functions of rays contributing to the geophones energy are calculated and used to decompose the seismic wavefield.This effectively enlarges the coverage of the reflection points and improves the transverse resolution.Compared with the traditional VSP–CDP stack imaging,the proposed methods extends the imaging range,yields higher horizontal resolution,and is more adaptable to complex geological structures.The method is applied to model a complex structure in the K-area.The results suggest that the wave group of the target layer is clearer,the resolution is higher,and the main frequency of the crosswell seismic section is higher than that in surface seismic exploration The effectiveness and robustness of the method are verified by theoretical model and practical data.
文摘I present results of processing and structural interpretation of narrow-angle seismic reflection data recorded over an area of 30 × 50 km located in the southern part of the North Apuseni Mts, Romania. The investigated area is characterized by complex subsurface geology and rough topography. The seismic measurements were performed along five linear profiles, P1-P5, using an active spread of 96 geophones for each shot point;geophone spacing was 25 m. The length of each acquisition line is greater than 10 km. The signal-to-noise ratio of these data varies along the lines and its variation is considered to be an effect of rough topography, complex subsurface geology and varying surface conditions encountered during seismic data acquisition. The data processing was performed using a standard processing flow but with different processing parameters from one data set to another. I obtained five depth-converted migrated seismic sections after data processing. The accuracy of the depth values depends on that of the stacking velocities obtained from the velocity analyses performed on the filtered seismic data. Borehole information is not available, the investigated area belonging to the areas investigated for hydrocarbons. Each seismic section shows a different structural image of the subsurface and provides useful information about the tectonic and stratigraphic evolution of the investigated area. I obtained various structural images of the subsurface after the interpretation of the depth-converted migrated seismic sections, from a simple one with undeformed and inclined reflectors to a complex one with folded and faulted reflectors, especially the older ones. I interpreted intrusive bodies piercing through the overlying sediments, which are in good agreement with the results of older geophysical studies.
文摘Adhesion molecule CD146(100-130kDa)belongs to the immunoglobulin super family and it is originally identified as a biomarker for melanoma.Recently,CD146 is found as novel target molecule on endothelial cell and involved in tumor angiogenesis.Also CD146 is considered as critical molecule in cell invasion and anti-CD146 antibody could inhibit tumor metastasis and angiogenesis through its down regulation of NFk.In this report,we study the quantitative detection of the CD146 molecule in positive serum with the TIRIE biosensor.
基金supported by National Geoscience Database and Geological Survey of Iran
文摘The purpose of this study is to evaluate the Spectral Angle Mapper （SAM） classification method for determining the optimum threshold （maximum spectral angle） to unveil the hydrothermal mineral assemblages related to mineral deposits. The study area indicates good potential for Cu-Au porphyry, epithermal gold deposits and hydrothermal alteration well developed in arid and semiarid climates, which makes this region significant for Advanced Spaceborne Thermal Emission and Reflection Radiometer （ASTER） image processing analysis. Given that achieving an acceptable mineral mapping requires knowing the alteration patterns, petrochemistry and petrogenesis of the igneous rocks while considering the effect of weathering, overprinting of supergene alteration, overprinting of hypogene alteration and host rock spectral mixing, SAM classification was implemented for argillic, sericitic, propylitic, alunitization, silicification and iron oxide zones of six previously known mineral deposits： Maherabad, a Cu-Au porphyry system; Sheikhabad, an upper part of Cu-Au porphyry system; Khoonik, an Intrusion related Au system; Barmazid, a low sulfidation epithermal system; Khopik, a Cu-Au porphyry system; and Hanish, an epithermal Au system. Thus, the investigation showed that although the whole alteration zones are affected by mixing, it is also possible to produce a favorable hydrothermal mineral map by such complementary data as petrology, petrochemistry and alteration patterns.
文摘The safety accidents caused by collapse column water diversion occur frequently, which has great hidden danger to the safety production of coal mine. Limited by the space of underground, the detection of collapse column on the outside of working face has been a difficult problem. Based on this, numerical simulation and imaging research were carried out in this paper. The results indicate that when a seismic source near the roadway is excited, a part of seismic wave propagates along the roadway direction, namely direct P-wave, direct S-wave and direct Love channel wave.<span style="font-family:;" "=""> <span style="font-family:Verdana;">When the body waves and Love channel wave propagating to the outside<span style="font-family:;" "=""> <span style="font-family:Verdana;">of working face meet the interface of collapse column, the reflected Love channel wave and reflected body waves are generated.<span style="font-family:;" "=""> <span style="font-family:Verdana;">Reflection <span style="font-family:Verdana;">body <span style="font-family:Verdana;">waves and direct waves are mixed in time domain, which is difficult to identify in seismic records, while reflected Love channel wave whose amplitude is relatively strong. The <span style="font-family:Verdana;">reflected <span style="font-family:Verdana;">Love channel wave which has a large interval from other wave trains in the time domain is easily recognizable in seismic record,<span style="font-family:;" "=""> <span style="font-family:Verdana;">which<span style="font-family:;" "=""> <span style="font-family:Verdana;">makes it suitable for advanced detection of collapse column. The signal-to-noise ratio of X component is higher than that of Y component and Z component. According to the seismic records, polarization filtering was carried out to enhance the effective wave, which removed the interference waves, and the signal was migrated to get the position parameters of collapse column interface, which was basically consistent with the model position.
基金supported by the Jilin Province Science and Technology Development Plan Item (No.20240402068GH)。
文摘To identify coatings and analyze the anti-detection capabilities of camouflage patterns, material samples can be prepared using the super-pixel segmentation method. A spectral polarization imaging system is developed, based on the principle of bidirectional reflectance distribution function(BRDF), to obtain spectral reflection intensities of coatings at full spatial angles, and use polarization images to calculate the refractive index by the Fresnel equation. The index is then coupled into TorranceSparrow model to simulate the spectral scattering intensity to mutually verify the experimental results. The spectral scattering characteristics of standard camouflage patterns are then revealed and pinpoint the signature band and the angle of reflecting sensitivity.
基金supported by the National Natural Science Foundation of China(Grant Nos.61372102 and 61571183)
文摘The vibration is one of the important factors affecting imaging quality of conventional remote sensing imaging because the relative motion between the imaging system and the target can result in the degradation of imaging quality. The influence of the vibration of the detector in the test path on reflective ghost imaging （RGI） is investigated theoretically and experimentally. We analyze the effects of the vibrating amplitude and velocity. The results demonstrate that the microvibrations of the bucket detector have almost no impact on the imaging resolution and signal-to-noise ratio （SNR） of RGI, i.e., the degradation of imaging quality caused by the vibration of the detector can be overcome to some extent. Our results can be helpful for remote sensing imaging.
基金Fundamental Research Funds for the Central Universities,China
文摘In recent years,there has been a backlash of sorts and the authenticity of images has been routinely questioned.Seeing is no longer believing.There is an urgent need for robust image forensic techniques to expose photo forgery.This paper proposed a novel and effective technique to expose image forgery using inconsistent reflection.More specifically,a new technique was presented to calculate reflection line midpoint,the definition of midpoint ratio was given,and three standards were proposed and employed to detect image forgery.Accuracy and effectiveness of the proposed technique were evaluated using a data set consisting of 200 authentic and forged images.Experimental results indicate that the proposed method can detect image forgery with very high success rate.
基金supported by the Fundamental Research Funds for the Central Universities(N2001020)the National Natural Science Foundation of China(41201359).
文摘Sand dust belts span approximately one-fifth of the global land surface.In these regions,dust tends to settle on vegetation surfaces,altering the observed reflectance and affecting remote sensing detections.To enhance the accuracy of maize growth monitoring in dust-affected regions,this study aims to quantify the effect of sand dust retention on maize during the tasseling stage in the Kashgar Prefecture,Xinjiang Uygur Autonomous Region,China,by analyzing changes in canopy reflectance and vegetation indices.First,field sampling was conducted to measure the key canopy structure parameters and dust retention levels of maize,and laboratory spectral measurements were performed on leaf spectral properties under gradient dust retention.The measured data were then used to drive the LargE-Scale remote sensing data and image Simulation framework(LESS)model for simulating realistic maize canopy spectra across different dust levels,with validation against Sentinel-2 imagery.Second,on the basis of the simulated and satellite-derived spectra,the dust resistance of 36 common vegetation indices was systematically evaluated,and new robust dust-resistant indices were developed.The results showed that compared with dust-free maize,the canopy reflectance of dust-retained maize followed an increase–decrease–increase pattern,with critical turning points at 735 and 1325 nm.The maximum reflectance difference of–0.11755(change rate:29.002%)occurred within the 735–1325 nm range at 24 g/m^(2)dust retention,and the minimum reflectance difference of 0.04285(change rate:148.950%)was observed in the 350–735 nm range under the same dust retention level.Among the 36 vegetation indices,only the global environment monitoring index(GEMI)and the ratio of transformed chlorophyll absorption in reflectance index to optimized soil-adjusted vegetation index(TCARI/OSAVI)exhibited dust resistance,with GEMI being effective below 6 g/m^(2)and TCARI/OSAVI remaining stable across all levels(average ratio:0.970).The newly developed indices in this study,(RE3–RE2)/(NIR–RE2),(RE3–RE2)/(RE4–RE2),and(NIR–RE2)/(RE4–RE2),retained values within the predefined dust-resistant range over the full dust retention levels of 0–24 g/m^(2),thus showing a more stable dust resistance compared with the commonly used 36 vegetation indices.Specially,(RE3–RE2)/(RE4–RE2)performed the most robustly in Sentinel-2 imagery,that is,58.020%of pixels were within the dust-resistant range,and an average ratio of 0.937 was obtained for the original-spectra index.This study provides a scientific basis for crop monitoring and management in dust-affected regions.
基金supported by National Petroleum Major Project(Grant No.2011ZX05020-008)
文摘Fracture identification is important for the evaluation of carbonate reservoirs. However, conventional logging equipment has small depth of investigation and cannot detect rock fractures more than three meters away from the borehole. Remote acoustic logging uses phase-controlled array-transmitting and long sound probes that increase the depth of investigation. The interpretation of logging data with respect to fractures is typically guided by practical experience rather than theory and is often ambiguous. We use remote acoustic reflection logging data and high-order finite-difference approximations in the forward modeling and prestack reverse-time migration to image fractures. First, we perform forward modeling of the fracture responses as a function of the fracture-borehole wall distance, aperture, and dip angle. Second, we extract the energy intensity within the imaging area to determine whether the fracture can be identified as the formation velocity is varied. Finally, we evaluate the effect of the fracture-borehole distance, fracture aperture, and dip angle on fracture identification.
基金The National Natural Science Foundation of China under contract Nos 41504084 and 41274120
文摘One of the problems experienced in marine geophysical exploration is that the layered features in the migration imaging profile are blurred and the seismic energy reflected is weaker in the middle or lower parts. In this study we model the seismic wavefield records in the undulating seafloor when there is both a slight change and significant change in seafloor topography to analyze its influence on the seismic reflection data and migration imaging profiles. We compare and analyze the wave field records collected at the same point on the original and modified velocity models, and the cross-bonding resulting migration imaging profiles. The results show that whether the seismic reflection data collection is performed along the direction of the survey line or against the direction of the survey line, slight changes in the seafloor topography have little effect on the wave field records and the migration profile, while significant changes in the seafloor topography have great effect on both the wave field records and migration profile.
基金supported by the Kansas Department of Transportation and the Kansas Corporation Commission
文摘High-resolution seismic reflections have been used effectively to investigate sinkholes formed from the dissolution of a bedded salt unit found throughout most of Central Kansas. Surface subsidence can have devastating effects on transportation structures. Roads, rails, bridges, and pipelines can even be dramatically affected by minor ground instability. Areas susceptible to surface subsidence can put public safety at risk. Subsurface expressions significantly larger than surface depressions are consistently observed on seismic images recorded over sinkholes in Kansas. Until subsidence reaches the ground surface, failure appears to be controlled by compressional forces evidenced by faults with reverse orientation. Once a surface depression forms or dissolution of the salt slows or stops, subsidence structures are consistent with a tensional stress environment with prevalent normal faults. Detecting areas of rapid subsidence potential, prior to surface failure, is the ultimate goal of any geotechnical survey where the ground surface is susceptible to settling. Seismic reflection images have helped correlate active subsidence to dormant paleofeatures, project horizontal growth of active sinkholes based on subsurface structures, and appraise the risk of catastrophic failure.
基金supported by the National Natural Science Foundation of China 62175153the Shanghai Science and Technology Commission 21S902700.
文摘Objective:We applied hyperspectral imaging(HSI)system to distinguish early caries from soundand pigmented areas.It will provide a theoretical basis and technical support,for research anddevelopment of an instrument that could be used for screening and detection of early dentalcaries.Methods:Eighteen extracted human teeth(molars and premolars),with varying degrees ofnatural pathology and no degree of decay involving dentin were obtained.HSI system with awavelength range from 400 to 1000nm was used to obtain images of all 18 teeth containingsound,carious and pigmented areas.We compared the spectra of the wavebands at both 500 nmand 780 nm from the different tooth states,and the reflectance diference bet ween sound versuscarious lesions and sound versus pigmented areas,respectively.Results:There was a slight diference in refectance bet ween carious areas and pigmented areas at500 nm.A substantial difference was additionally noted in refectance bet ween carious areas andpigmented areas at 780 nm.Conclusion:The results have shown that the interference of tooth surface pigment can be elim-inated in the near-infrared(NIR)waveband,and the caries can be effectively identifed from the pigmented areas.Thus,it could be used to detect carious areas of teeth in place of the traditionalvisual inspection method or white light endoscopy.Clinical significance:The NIR difused light signal enables the identification of early caries frompigment and other interference,providing a reasonable detection tool for early detection andearly treatment of teeth diseases.
基金financial supports from National Natural Science Foundation of China(51772135)the Ministry of Education of China(6141A02022516)+4 种基金the Fundamental Research Funds for the Central Universities(11619103)the China Postdoctoral Science Foundation(2019M663376)the Natural Science Foundation of Guangdong Province,China(Grant Nos.2017A020215135 and2018A030310659)Guangdong Basic and Applied Basic Research Foundation(2020A1515011377)the Science and Technology Program of Guangzhou,China(Grant No.201804010432)。
文摘High ultraviolet(UV)stability and low dark current(Idark)are necessary for high-quality perovskite photodetectors(PDs).TiO^(2)thin film is known as effective electron-transport-layer(ETL)for perovskite devices.However,common spin-coated TiO^(2)ETLs endow many surface defects and have strong UV photocatalytic effect to decompose perovskite materials,resulting in inferior stability of devices.In this work,TiO^(2)bilayer film(Bi-TiO^(2))has been fabricated by combining spin-coating and atomic-layer-deposition process and its positive effects on UV stability and Idarkof Cs2 AgBiBr6-based PDs have been revealed for the first time.It is demonstrated that Bi-TiO^(2)possesses fewer surface defects and smoother morphology with type II band alignment,which is beneficial to suppress photocatalytic activity of TiO^(2)and reduce carrier recombination at the interface.After accelerated strong UV aging treatment,the PD with Bi-TiO^(2)maintains excellent performance,whereas the PD with spin-coated TiO^(2)film dramatically deteriorate with on-off ratio drops from~102 to~2.Besides,the Idarkof PD remarkably decreases from~10^(-8) A to~10^(-10) A after bilayer optimization.Furthermore,we have integrated the corresponding PDs into a self-built imaging system adopting diffuse reflection mode.This work suggests a feasible approach to fabricate TiO^(2)/Cs2 AgBiBr6-based PDs with remarkable UV tolerance for imaging applications.
基金Fundamental Research Funds for the Central Universities,China(No.2232015D3-25)
文摘The rapid development of image processing techniques has made it extremely easy to alter the content of images or create newimages.So photographs,which appear in magazines,social media,and political attacks,can no longer be trusted.A novel and effective technique is proposed in this paper to expose image forgery using inconsistent reflection vanishing point(RVP).More specifically,the definition of error distance is given,sin^2()-based function is proposed to normalize error distance,and a reasonable threshold value is set to detect image forgery.The experimental data and results are presented to demonstrate the accuracy and effectiveness of the technique.
基金supported by the Key Program of the National Natural Science Foundation of China (Grant No. 40537031)the National Natural Science Foundation of China (Grant No. 40875013)+2 种基金the National Defense Basic Scientific Research Program of China (Grant No. A1420080187)the National High Technology Research and Development Program of China (GrantNo. 2006AA12Z152)Xianyang Normal University Research Fund (Grant No. 06XSYK268)
文摘This paper gives the relation between spatial ray and its projection on paper plane based on the vector form of reflective law. Using the method of prism expansion, it obtains the exact expression of the exit height. The exit height can ensure that the incident rays, at arbitrary direction and arbitrary angle, after several transmission and reflection in the two right-angle reflectors, finally pass through the exit surface. Furthermore, it analyses the effects of different parameters on the exit height through computer simulation, and some important conclusions are obtained. The physical meaning of the sign of exit height is described, and the exact expression of the minimal thickness of the large optical path difference wind imaging interferometer is gained. This work is of great scientific significance to the static, real- time simultaneous detection of atmospheric wind field, and it will provide a theoretical and practical guidance for the miniaturization design and engineering realization of wind imaging interferometer.
