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Research on the “∞”-shaped laser scanning welding process for aluminum alloy
摘要： To solve the problems of poor quality and insu?cient joint strength of aluminum alloy weld, a laser scanning welding test platform for aluminum alloy was built. Taking the butt welding of 5052 aluminum alloy with 5 mm and 3 mm thick specimens as the research objects, the study of a “∞”-shaped laser scanning welding process was conducted, and the similarities and di?erences between the welding process and that of single pass laser welding were compared. The in?uence of “∞”-shaped laser scanning welding parameters on the weld formation was investigated by the factor variable method. The change of the surface morphology and dynamic evolution of the molten pool was observed by a high-speed camera system. The optimal combination of the welding parameters was obtained by an orthogonal test. The research showed that the “∞”-shaped laser scanning welding pool had good stability and a good weld quality. Under suitable welding parameters, the length and width of the molten pool could be increased signi?cantly compared with those of the single pass laser welding. The growth rate of the length and width could reach 110.19% and 57.69%, respectively. The surface of the weld was evenly distributed with dense ?sh scales, and the porosity was less than 1%. The tensile strength of the specimen could reach 205.242 MPa, which was 93% that of the base metal; the topography of fracture was full of dimples, and the metallographic structure of the weld was ?ne and distributed with equiaxed dendrites.
关键词： Weld appearance,Weld performance,Laser technique,“∞”-shaped laser scanning welding,Molten pool characteristics
更新于2025-11-28 14:24:20
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High tension electrocution death: New histopathological cardiac tools by Confocal Laser Scanning Microscope
摘要： In deaths due to electrocution intraepidermal separation, vacuolation of epidermal cells, “swiss cheese” aspect of the superficial part of epidermis (swollen and with multiple vescicles), metallization, necrosis of collagenous fibers, cardiomyocytes alterations are microscopically described. No cardiac nerve damage due to electricity is actually reported in literature. In this work we tried to find new morphological signs in the hearts of deaths due to electrocution. In three cases of deaths due to electrocution, in which forensic autopsies were performed within 36 h of the death, heart specimens were taken at the level of common trunk of the left coronary artery. The myocardium histological examination at optical microscope and Confocal Laser Scanning Microscope (CLSM) revealed fragmentation of cardiomyocytes, nerve trunks damage with hydropic swelling of the nerve fibers, interstitial and sub-nerve-sheath edema, very dishomogenous distribution of the natural fluorescence of the neurofilaments, coarctation of epicardial gangliar cells with cytoplasmic cleft and irregular fluorescence pattern. Identification of S-100 protein by immunohistochemistry can help to better observe the hydropic swelling of the nerve fibers and the central cytoplasmic clefts. These alterations could be used in future as specific signs of the passage of the electrical current through the heart. We recommend heart specimens at the level of common trunk of the left coronary artery in all the cases of suspected electrocution, to better evaluate cardiac nerve trunks damages and alterations.
关键词： Confocal laser scanning microscope (CLSM),Histology,Cardiac nerves,Electrocution,Fluorescence,Heart
更新于2025-11-21 11:20:42
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Evaluation of various tissue-clearing techniques for the three-dimensional visualization of liposome distribution in mouse lungs at the alveolar scale
摘要： Purpose: To develop a three-dimensional visualization method for evaluating the distribution of pulmonary drug delivery systems and compare four tissue-clearing techniques (ClearT2, CUBIC, ScaleS, and SeeDB2) using intrapulmonary liposomes as drug carriers. Methods: Rhodamine B-labeled liposomes were administered intrapulmonarily to mice using a MicroSprayer, and then fluorescent-labeled tomato lectin was administered intravenously to visualize the general lung structure. Tissue-clearing treatment of the mouse lungs was performed using the standard protocols of the ClearT2, CUBIC, ScaleS, and SeeDB2 techniques. Lung clearing was clarified using laser-scanning confocal microscopy, and three-dimensional images were reconstructed. Results: Fluorescent-labeled tomato lectin was preserved using ClearT2 and SeeDB2 but not using CUBIC and ScaleS. In addition, the liposomes were stable in ClearT2 reagent, but they were mostly degraded in other reagents by surface-active agents. ClearT2 treatment enabled the three-dimensional visualization of intrapulmonary rhodamine B-labeled liposomes at the alveolar scale. Conclusions: These results suggest that the ClearT2 tissue-clearing technique was appropriate for the three-dimensional visualization of intrapulmonary liposomes at the alveolar scale. This study provides important information for selecting and optimizing suitable optical tissue-clearing techniques in lungs for evaluating the distribution of pulmonary drug delivery systems.
关键词： fluorescence preservation,Intrapulmonary distribution,inhalation,liposomes,drug delivery systems,laser-scanning confocal microscopy
更新于2025-11-21 11:08:12
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3D laser scanning and digital restoration of an archaeological find
摘要： The current paper demonstrates the digital recreation and 3D printing of a missing fragment of an ancient ceramic pottery following digitization using a three dimensional laser scanning. The resulting point-cloud of the laser scans was treated with a series of advanced software for the creation of surfaces and ultimately for a digital model. An analytical methodology is presented revealing the step by step approach, which is an innovative way of recreating a missing fragment. Such approach aims to demonstrate the level of contribution that the ever evolving computer based technologies and 3D printing could bring to cultural heritage. The reverse engineering method presented for the reconstruction of a ceramic pottery, which is a part of the larger field of digital archaeology, is believed to benefit a variety of interested parties including 3D CAD users and designers, archaeologists and museum curators.
关键词： 3D printing,archaeological find,reverse engineering,digital restoration,3D laser scanning
更新于2025-11-21 11:01:37
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Vibrational spectroscopic imaging and live cell video microscopy for studying differentiation of primary human alveolar epithelial cells
摘要： Alveolar type II(ATII) cells in the peripheral human lung spontaneously differentiate towards alveolar type I(ATI) cells, thus enabling air-blood barrier formation. Here, linear Raman and coherent anti-Stokes Raman scattering (CARS) microscopy are applied to study cell differentiation of freshly isolated ATII cells. The Raman spectra can successfully be correlated to gradual morphological and molecular changes during cell differentiation. Alveolar surfactant rich vesicles in ATII cells are identified based on phospholipid vibrations, while ATI-like cells are characterized by the absence of vesicular structures. Complementary, CARS microscopy allows for 3D visualization of lipid vesicles within ATII cells and their secretion, while hyperspectral CARS enables the distinction between cellular proteins and lipids according to their vibrational signatures. This study paves the path for further label-free investigations of lung cells and the role of the pulmonary surfactant, thus also providing a basis for rational development of future lung therapeutics.
关键词： confocal laser scanning microscopy,confocal Raman microscopy,pneumocyte type II differentiation,CARS microscopy,cell imaging
更新于2025-09-23 15:23:52
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Accuracy and reliability evaluation of 3D-LS for the discontinuity orientation identification with different registration/georeferencing modes
摘要： With the aid of three-dimensional laser scanning (3D-LS), a lot of geometric properties of rock discontinuities can be derived from the point cloud data. Due to the complexity of registration and georeferencing of multi-station point data, geological engineers tend to simplify processing by using single-station point data and orienting coarsely. However, there is a lack of accuracy and reliability study in the identification of discontinuity orientations with 3D-LS using different registration/georeferencing modes. In this study, the single-station scanning without registration/georeferencing was applied first to examine the accuracy and reliability of the scanner’s built-in direction system. After that, two types of automated registration/georeferencing modes were examined for the accuracy in rock mass discontinuity analysis. The results show that the dip angle measured by the scanner’s built-in directional system is reliable, accurate and can meet engineering requirements, while the dip direction measured by the scanner’s built-in directional system is unreliable and inaccurate. The dip direction is consistent but inaccurate through the semi-automated registration using natural point features and georeferencing by the scanner’s built-in directional system. Only through real-time kinematic (RTK) registration/georeferencing can the dip direction be reliable and accurate. It is observed that orientations captured by 3D-LS can be more accurate with RTK registration/georeferencing than manual survey.
关键词： orientation,3D laser scanning,rock discontinuities,georeferencing,registration
更新于2025-09-23 15:23:52
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[IEEE 2018 26th International Conference on Geoinformatics - Kunming (2018.6.28-2018.6.30)] 2018 26th International Conference on Geoinformatics - Multilevel Solar Potential Analysis of Building Based on Ubiquitous Point Clouds
摘要： Solar potential analysis is essential for Building Information Modeling (BIM) applications, like photovoltaic installation. The estimation of solar potential on rooftops has been widely discussed, whereas the study on fa?ade is still limited. Benefit from the development of various sensors, ubiquitous point clouds are now widely and easily captured by photogrammetry, laser scanning or other technologies, to represent the building geometry. This paper proposes a method for solar potential analysis on both rooftops and fa?ades, using ubiquitous point cloud collected by Unmanned Aerial Vehicle (UAV) and Terrestrial Laser Scanning (TLS). One building with different orientations is selected for the case study. Results show that the proposed method is valid for multilevel solar potential analysis of buildings.
关键词： laser scanning,solar potential,ubiquitous point cloud,Building Information Modeling (BIM)
更新于2025-09-23 15:23:52
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The Placement of Digitized Objects in a Point Cloud as a Photogrammetric Technique
摘要： The frequency of video-capturing collision events from surveillance systems are increasing in reconstruction analyses. The video that has been provided to the investigator may not always include a clear perspective of the relevant area of interest. For example, surveillance video of an incident may have captured a pre- or post-incident perspective that, while failing to capture the precise moment when the pedestrian was struck by a vehicle, still contains valuable information that can be used to assist in reconstructing the incident. When surveillance video is received, a quick and efficient technique to place the subject object or objects into a three-dimensional environment with a known rate of error would add value to the investigation. In addition, once the objects have been placed into the three-dimensional environment, the investigator would then be able to observe the physical evidence and environment from any perspective, including viewing and measuring what cannot be seen in the video perspective. In this research, the proposed photogrammetric technique of visually placing objects within three-dimensional laser scans will be evaluated. This research aims to quantify the rate of error of taking measurements of these objects to known fixed reference points both in and out of view of the camera, and provide an efficient technique that can be employed by reconstructionists using only one software package. As a result of this research, the authors have developed an expedient, less time-intensive photogrammetric technique for the placement of three-dimensionally scanned objects and environments. This technique can take less than half of the time of a conventional photogrammetric solution.
关键词： Photogrammetry,Video footage,3D scanning,Surveillance video,Laser scanning,Scanagrammetry,Accident reconstruction,Drivecam,Dashcam
更新于2025-09-23 15:22:29
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Multispectral Airborne LiDAR Data in the Prediction of Boreal Tree Species Composition
摘要： Multispectral light detection and ranging (LiDAR) instruments, such as Optech Titan, record intensities at multiple wavelengths and these intensities can be used for tree species prediction in the same way as multispectral image data. In this paper, our main objective was to compare the accuracy of tree species prediction in a boreal forest area using multispectral LiDAR, the 1064-nm wavelength channel ('unispectral LiDAR'), and unispectral LiDAR with auxiliary aerial image data. We also evaluated the effect of the widely used intensity range correction method. We classified the main tree species of field plots using linear discriminant analysis (LDA) and predicted the species-specific volume proportions (%) for Scots pine (Pinus sylvestris), Norway spruce (Picea abies), and broadleaved trees using the k-nearest neighbor imputation. The effect of intensity correction on prediction errors for the dominant tree species was evaluated using optimal parameters derived from: 1) minimal intensity difference between flight lines; 2) parameters suggested by theory; and 3) uncorrected data. Although the range correction increased the classification accuracy slightly, it was observed to be ambiguous, and not consistent with theory for canopy echoes. Regardless, the intensity values were useful for the prediction of dominant tree species and species' volume proportions. The results for the dominant tree species classification using multispectral LiDAR [overall accuracy (OA) 88.2%, kappa 0.79] were comparable to the use of unispectral LiDAR and aerial images (OA 89.1%, kappa 0.81). We conclude that the multispectral LiDAR may become a useful tool in operational species-specific forest inventories.
关键词： laser backscatter intensity,k-nearest neighbor (k-NN),Intensity correction,linear discriminant analysis (LDA),multispectral airborne laser scanning,tree species classification
更新于2025-09-23 15:22:29
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Quantification and analysis of geomorphic processes on a recultivated iron ore mine on the Italian island of Elba using long-term ground-based lidar and photogrammetric SfM data by a UAV
摘要： This study focuses on the quanti?cation and analysis of geomorphic processes on the barely vegetated slopes of a recultivated iron ore mine on the Italian island of Elba using photographs from terrestrial laser scanning (TLS) and digital photogrammetry by an unmanned aerial vehicle (UAV) over a period of 5 1/2 years. Beside this, the study tried to work out the potential and the limitations of both methods to detect surface changes by geomorphic process dynamics within a natural environment. Both UAV and TLS show the pattern of the erosion and accumulation processes on the investigated slope quite well, but the calculated amounts differ clearly between the methods. The reasons for these differences could be found in the different accuracies (variable level of detections) of the methods and the different viewing geometries. Both effects have an impact on the detectable process dynamics over different timescales on the slope and their calculated amounts, which in both cases can lead to an underestimation of erosion and accumulation by ?uvial processes.
关键词： terrestrial laser scanning,erosion,geomorphic processes,UAV,recultivated iron ore mine,accumulation,digital photogrammetry
更新于2025-09-23 15:21:21