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Monitoring of CFA pile test using three dimensional laser scanning and distributed fiber optic sensors
摘要： The results obtained during a pile test are dependent on a number of factors. However, conventional monitoring systems like vibrating wire strain gauges and the extensometers can only measure the variations of strain and displacement at discrete locations at which they are installed in a pile. In order to identify the behavior of Continuous Flight Auger (CFA) pile, the distributed fiber optic monitoring system and three-dimensional laser scanning collected the strain and point clouds data during the pile test with conventional vibrating wire strain gauges, extensometers. Based on the Brillouin Optical Time Domain Reflectometry (BOTDR) fiber optic strain profile, the profiles of axial load, skin friction, displacement can be obtained. The fiber optic monitoring system was compared with conventional systems, and it was found that the ability to measure the full strain profiles is highly advantageous in determining the performance of the pile and in detecting the behavior of CFA pile. The displacement of the pile was measured by the LVDT at the top of the pile and the results were compared with the laser scanning results. In this study, the negative skin friction was detected by BOTDR fiber optic strain profile near the top of the CFA pile. It was not able to define the reason of the negative skin friction from the other monitoring systems but the laser scanning results show that the ground movement due to the pull-out force of the anchor pile affects the negative skin friction. Although laser scanning is not able to measure the real-time data during the pile test, the extensive information can be taken into account by the monitored data from three-dimensional laser scanning.
关键词： Distributed fiber optic monitoring,BOTDR,CFA pile,Three-dimensional laser scanning
更新于2025-09-19 17:13:59
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Ultra-Widefield Laser Scanning Retina Imaging in Oculocutaneous Albinism
摘要： A 5-year-old girl with abnormalities of the skin and hair that were consistent with albinism had nystagmus and photophobia. Her skin color varied from yellow to milky white and hypopigmentation was appreciated by comparison with other family members. She received ultra-widefield laser scanning imaging (Daytona P200T; Optos) to observe the pigment of the fundus to make a definitive diagnosis of oculocutaneous albinism. The vortex veins and a hypoplasia of the macula were noted (Figure). Oculocutaneous albinism is characterized by photophobia, nystagmus, fundus hypopigmentation, and the absence of foveal pit.
关键词： Ultra-Widefield Laser Scanning Retina Imaging,Oculocutaneous Albinism,Ophthalmic Images
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE Conference on Control Technology and Applications (CCTA) - Hong Kong, China (2019.8.19-2019.8.21)] 2019 IEEE Conference on Control Technology and Applications (CCTA) - Novel Micro Scanning with Integrated Atomic Force Microscope and Confocal Laser Scanning Microscope
摘要： Integrated atomic force microscope (AFM) and confocal laser scanning microscope (CLSM) can quickly obtain the three-dimensional (3-D) surface of the sample in large scanning range and recover the region of interesting (ROI) in nanoscale resolution. However, the traditional cooperative algorithm for integrated microscopes occupies too much scanning time. In this work, we develop a novel cooperative algorithm for the integrated microscopes to reduce scanning time of AFM and achieve higher scanning speed. First, the calibration of the microscopes will be implemented. Next, CLSM starts a large range scan first and then define the region of interesting (ROI) by edge detection. And then, the scan regions of the AFM are arranged based on the ROI and adaptive scanning region method is proposed to reduce the scanning time. Furthermore, variable speed scanning based on the height information obtained from CLSM image is applied to increase the AFM scanning speed. Finally, the scanning images obtained from AFM and CLSM are merged together. A series of experimental results show that proposed cooperative algorithm can save approximately 69.2% of scanning time compared with that obtained by traditional cooperative algorithm.
关键词： Atomic force microscope (AFM),adaptive scanning range,confocal laser scanning microscope (CLSM),regions of interest (ROI),variable speed scanning
更新于2025-09-16 10:30:52
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Correlated Secondary Ion Mass Spectrometry-Laser Scanning Confocal Microscopy Imaging for Single Cell-Principles and Applications
摘要： Secondary ion mass spectrometry (SIMS) as a powerful surface analysis technique has been widely applied in semiconductor industry and geology research. Recently, with the development of instrumental technology, SIMS is attracting more and more attention in life sciences. SIMS can provide surface MS spectra, 2D/3D chemical images and depth profiling of substances simultaneously. The minimal lateral resolution of 2D SIMS imaging is 80?100 nm, and the longitudinal resolution of 3D SIMS imaging is about 1–5 nm. However, owing to lack of specific ions to render the structures of organelles, SIMS imaging for single cells still have great challenges. Optical microscopy, in particular laser scanning confocal microscopy (LSCM), has been emerged to be an indispensable technique for single cell imaging and can obtain high spatial 2D/3D imaging to visualize the structures of organelles. Thus, the combinational use of SIMS and LSCM, which takes advantages of SIMS for molecular imaging and LSCM for morphological imaging, has greatly extended the application of SIMS imaging and ensured its accuracy at single cells level, providing novel insights into better understanding of the biological events inside cells. In this review, we focus on the development and application of SIMS imaging and the correlated SIMS and LSCM imaging in the research of cell biology and drug discovery. We anticipate that the combinational use of SIMS and LSCM imaging has promising future in biomedicine and life sciences.
关键词： Cell biology,Single cell imaging,Laser scanning confocal microscopy,Correlated secondary ion mass spectrometry and laser scanning confocal microscopy imaging,Secondary ion mass spectrometry,Review
更新于2025-09-16 10:30:52
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Robust and automatic modeling of tunnel structures based on terrestrial laser scanning measurement
摘要： The terrestrial laser scanning technology is increasingly applied in the deformation monitoring of tunnel structures. However, outliers and data gaps in the terrestrial laser scanning point cloud data have a deteriorating effect on the model reconstruction. A traditional remedy is to delete the outliers in advance of the approximation, which could be time- and labor-consuming for large-scale structures. This research focuses on an outlier-resistant and intelligent method for B-spline approximation with a rank (R)-based estimator, and applies to tunnel measurements. The control points of the B-spline model are estimated specifically by means of the R-estimator based on Wilcoxon scores. A comparative study is carried out on rank-based and ordinary least squares methods, where the Hausdorff distance is adopted to analyze quantitatively for the different settings of control point number of B-spline approximation. It is concluded that the proposed method for tunnel profile modeling is robust against outliers and data gaps, computationally convenient, and it does not need to determine extra tuning constants.
关键词： Terrestrial laser scanning,health monitoring,rank-based estimator,B-spline approximation,robust modeling
更新于2025-09-16 10:30:52
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Nondestructive Estimation of the Above-Ground Biomass of Multiple Tree Species in Boreal Forests of China Using Terrestrial Laser Scanning
摘要： Above-ground biomass (AGB) plays a pivotal role in assessing a forest’s resource dynamics, ecological value, carbon storage, and climate change effects. The traditional methods of AGB measurement are destructive, time consuming and laborious, and an efficient, relatively accurate and non-destructive AGB measurement method will provide an effective supplement for biomass calculation. Based on the real biophysical and morphological structures of trees, this paper adopted a non-destructive method based on terrestrial laser scanning (TLS) point cloud data to estimate the AGBs of multiple common tree species in boreal forests of China, and the effects of differences in bark roughness and trunk curvature on the estimation of the diameter at breast height (DBH) from TLS data were quantitatively analyzed. We optimized the quantitative structure model (QSM) algorithm based on 100 trees of multiple tree species, and then used it to estimate the volume of trees directly from the tree model reconstructed from point cloud data, and to calculate the AGBs of trees by using specific basic wood density values. Our results showed that the total DBH and tree height from the TLS data showed a good consistency with the measured data, since the bias, root mean square error (RMSE) and determination coefficient (R2) of the total DBH were ?0.8 cm, 1.2 cm and 0.97, respectively. At the same time, the bias, RMSE and determination coefficient of the tree height were ?0.4 m, 1.3 m and 0.90, respectively. The differences of bark roughness and trunk curvature had a small effect on DBH estimation from point cloud data. The AGB estimates from the TLS data showed strong agreement with the reference values, with the RMSE, coefficient of variation of root mean square error (CV(RMSE)), and concordance correlation coefficient (CCC) values of 17.4 kg, 13.6% and 0.97, respectively, indicating that this non-destructive method can accurately estimate tree AGBs and effectively calibrate new allometric biomass models. We believe that the results of this study will benefit forest managers in formulating management measures and accurately calculating the economic and ecological benefits of forests, and should promote the use of non-destructive methods to measure AGB of trees in China.
关键词： nondestructive method,above-ground biomass,DBH,bark roughness,terrestrial laser scanning
更新于2025-09-16 10:30:52
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Automated Method for Detection of Missing Road Point Regions in Mobile Laser Scanning Data
摘要： The paper proposes a method supported by MATLAB for detection and measurement of missing point regions (MPR) which may cause severe road information loss in mobile laser scanning (MLS) point clouds. First, the scan-angle thresholds are used to segment the road area for MPR detection. Second, the segmented part is mapped onto a binary image with a pixel size of ε through rasterization. Then, MPR featuring connected 1-pixels are identi?ed and measured via image processing techniques. Finally, the parameters regarding MPR in the image space are reparametrized in relation to the vehicle path recorded in MLS data for a better understanding of MPR properties on the geodetic plane. Tests on two MLS datasets show that the output of the proposed approach can e?ectively detect and assess MPR in the dataset. The ε parameter exerts a substantial in?uence on the performance of the method, and it is recommended that its value should be optimized for accurate MPR detections.
关键词： occlusion,image processing,missing points,point cloud,mobile laser scanning
更新于2025-09-16 10:30:52
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Airborne Laser Scanning Cartography of On-Site Carbon Stocks as a Basis for the Silviculture of Pinus Halepensis Plantations
摘要： Forest managers are interested in forest-monitoring strategies using low density Airborne Laser Scanning (ALS). However, little research has used ALS to estimate soil organic carbon (SOC) as a criterion for operational thinning. Our objective was to compare three different thinning intensities in terms of the on-site C stock after 13 years (2004–2017) and to develop models of biomass (Wt, Mg ha?1) and SOC (Mg ha?1) in Pinus halepensis forest, based on low density ALS in southern Spain. ALS was performed for the area and stand metrics were measured within 83 plots. Non-parametric kNN models were developed to estimate Wt and SOC. The overall C stock was signi?cantly higher in plots subjected to heavy or moderate thinning (101.17 Mg ha?1 and 100.94 Mg ha?1, respectively) than in the control plots (91.83 Mg ha?1). The best Wt and SOC models provided R2 values of 0.82 (Wt, MSNPP) and 0.82 (SOC-S10, RAW). The study area will be able to stock 134,850 Mg of C under a non-intervention scenario and 157,958 Mg of C under the heavy thinning scenario. High-resolution cartography of the predicted C stock is useful for silvicultural planning and may be used for proper management to increase C sequestration in dry P. halepensis forests.
关键词： carbon silviculture,climate change,K-near neighbour,airborne laser scanning,carbon sequestration
更新于2025-09-16 10:30:52
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Surface Refining by Laser Scanning on Silicon Wafers
摘要： A YAG continue-wave laser has been used to refine the surface of silicon wafers in this study. During laser scanning, the irradiated region of the surface of the wafer experienced melting and subsequent recrystallization, which results in a redistribution of metal impurities in the molten pool along the depth direction. Cross-sectional micrographs of irradiated wafers have a clear boundary, which confirms the process of recrystallization, and the depth of molten region depends on the scanning parameters and the size of wafer. Secondary ion mass spectrometry measurements have been carried out to characterize the concentration of metal impurities. After redistribution of metal impurities, a final relative purity region was formed close to the surface. SIMS measurements demonstrate that the metal impurity concentration of the purity region has significantly reduced. The mechanism of the redistribution process of metal impurities in the molten pool has been qualitatively analyzed. All of the experimental results support that the CW laser scanning technology can effectively refine the specific surfaces of silicon wafers, and this technology has a great potential in the field of solar cells.
关键词： Silicon wafer,Laser scanning,Refining,Metal impurities,Recrystallization
更新于2025-09-16 10:30:52
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Nonlinear absorption and scattering of a single plasmonic nanostructure characterized by <i>x</i> -scan technique
摘要： Nonlinear nanoplasmonics is a largely unexplored research area that paves the way for many exciting applications, such as nanolasers, nanoantennas, and nanomodulators. In the field of nonlinear nanoplasmonics, it is highly desirable to characterize the nonlinearity of the optical absorption and scattering of single nanostructures. Currently, the common method to quantify optical nonlinearity is the z-scan technique, which yields real and imaginary parts of the permittivity by moving a thin sample with a laser beam. However, z-scan typically works with thin films, and thus acquires nonlinear responses from ensembles of nanostructures, not from single ones. In this work, we present an x-scan technique that is based on a confocal laser scanning microscope equipped with forward and backward detectors. The two-channel detection offers the simultaneous quantification for the nonlinear behavior of scattering, absorption and total attenuation by a single nanostructure. At low excitation intensities, both scattering and absorption responses are linear, thus confirming the linearity of the detection system. At high excitation intensities, we found that the nonlinear response can be derived directly from the point spread function of the x-scan images. Exceptionally large nonlinearities of both scattering and absorption are unraveled simultaneously for the first time. The present study not only provides a novel method for characterizing nonlinearity of a single nanostructure, but also reports surprisingly large plasmonic nonlinearities.
关键词： nonlinear absorption,absorption cross section,nonlinear scattering,single gold nanostructures,laser scanning microscopy,nanoplasmonics
更新于2025-09-16 10:30:52