Three-dimensional Laser Scanning Research Articles

Construction Quality Inspection Method of Substation Fabricated Structure Based on 3D Laser Scanning

The substation construction project is highly professional and comprehensive, requiring multiple disciplines’ cooperation. It is greatly affected by geographical and environmental factors and has the characteristics of high management requirements and difficult quality control in the construction process. Based on the good initial position of the point cloud to be registered, if this requirement cannot be met, the registered point cloud data is prone to the optimal local solution. Thus, this paper introduces three-dimensional laser scanning to detect the construction quality of the substation assembly structure. On this basis, the data registration method realizes the accurate point cloud registration, and the data’s main feature vector is extracted through a linear transformation. Through the spatial transformation of the principal axis direction, the registration of the point cloud number is completed. The problem of the optimal local solution of registration is effectively solved. The point cloud data model is created by actual data acquisition, and the influencing factors of reverse construction of the geometric model are analyzed. The specific implementation scheme is put forward to ensure the accuracy of the geometric model construction. The test verified the reasonable and effective application of 3D laser scanning in the prefabricated building installation. Besides, the effective method of the high-precision point cloud model data output is determined.

A State-of-the-Practice Review of Three-Dimensional Laser Scanning Technology for Tunnel Distress Monitoring

A State-of-the-Practice Review of Three-Dimensional Laser Scanning Technology for Tunnel Distress Monitoring

Effects of interlayer surface characteristics on the interface bonding between double-layered asphalt systems

ABSTRACT This study aims at comparing the surface characteristics of the interface between double-layered asphalt specimens composed of conventional or rubberised asphalt concrete mixtures. To this end, first, the double-layered asphalt specimens with a novel interlayer isolation film (IIF) in between were manufactured, and then the asphalt specimens were non-destructively separated at the layer interface. Subsequently, an ultra-high-resolution three-dimensional (3D) laser scanner was utilised to acquire the respective 3D point cloud data. Next, the 3D morphology of the interface between asphalt layers was reconstructed using image processing techniques, and the corresponding surface characteristics were determined accordingly. In this respect, three indicators of impact ratio (IR), degree of curvature (DC), and curvature ratio (CR), which are dependent together and developed in a successive approach, were developed respectively to quantitatively describe interlayer surface characteristics of adjacent layers. Subsequently, the relationship between the interface shear strength and interface characteristics of double-layered specimens was compared and analyzed. The results showed that the CR could effectively reflect the surface characteristics of the interface between double-layered asphalt specimens. Finally, the statistical analysis revealed that the interlayer surface characteristics (CR) statistically had a significant effect on the interface shear strength.

Ballistic penetration of high-entropy CrMnFeCoNi alloy: Experiments and modelling

Ballistic impact experiments are conducted on a CrMnFeCoNi high-entropy alloy (HEA) using spherical steel projectiles, to investigate the penetration behavior in a wide range of impact velocities (∼800 to 2300 m s−1). Penetration processes are captured by high-speed camera. Postmortem samples are characterized via three-dimensional laser scanning, scanning electron microscopy, electron backscatter diffraction, transmission electron microscopy and microhardness tests. Both depth and diameter of impact crater show a nearly linear increase with increasing impact velocity. Penetration induces increased hardness; hardness is the same near the crater bottom and the sidewall, and the peak hardness (∼400 Hv1.0) is independent of impact velocity. The penetration-induced hardening is caused by multiple deformation defects including dislocations, twins and kink bands (KBs). Quantitative analysis further reveals that KB boundaries have a 5–50° misorientation angle, and their density decreases with increasing misorientation angle. KB boundary density is higher near the crater bottom than near the crater sidewall, while this trend is inverse for twinning boundary density. A finite element method model based on measured static and dynamic mechanical properties reproduces experimental observations and is used for interpreting deformation mechanisms.

A preliminary study on the method of identifying Zheng by bridges

Zheng is a Chinese traditional plucked instrument with a history of over 2,500 years, and it is regarded as one of the most important instruments in Chinese traditional music. The early “Zheng” obtained from archaeological excavations is generally assessed via the exclusion method. If the shape of an unearthed “wooden instrument” is not Zhu, Qin, nor Se, then it is certainly a Zheng. However, this method does not emphasize the characteristics of Zheng, which has certain limitations. Based on the study on the difference between Zheng and other plucked instruments, this article suggests that regularly arranged bridges are the most significant difference between Zheng and other instruments with similar shapes. Hence, the presence of regular bridge indentations on the wood panel should be the basis for identification. Accordingly, portable microscopes, three-dimensional laser scanners, and other equipment were employed to investigate modern Zheng samples. Via the analyses of the bridge arrangement, indentation depth, and other aspects, a set of methods that can be adopted to identify the plucked instrument was preliminarily established.

3D Virtual reconstruction of asphalt mixture microstructure based on rigid body dynamic simulation

ABSTRACT This paper presents a virtual generation method for the heterogeneous microstructure of asphalt mixtures. The coarse aggregates used in the digital asphalt mixture were derived from real aggregates captured by a three-dimensional (3D) laser scanner. Then, a rigid-body dynamic simulation framework was proposed to generate a stable skeletal structure composed of coarse aggregates similar to those formed by compaction. Furthermore, FAM and air voids were generated based on the generated aggregate skeleton and the assumption of equal thickness of FAM film. To prove the reliability of the model, the air voids of the digital asphalt mixture samples were verified by comparison with real specimens. The generated digital specimens were also applied to finite element method (FEM) simulations to predict the dynamic modulus of the asphalt mixture and the simulated results were in good agreement with the experimental results. The method can be applied to study the spatial distribution of asphalt mixture components, the movement pattern of aggregate particles during compaction and numerical simulations at the microscopic scale.

Autonomic innervation, a peripheral glial cell web, and a novel S100B expressing interstitial cell type impart structural and functional complexity to the sinoatrial node.

The sinoatrial node (SAN) of the heart produces rhythmic action potentials, generated via calcium signaling within and among pacemaker cells. Our previous work has described the SAN as composed of a HCN4+-pacemaker cell meshwork, which merges with a network of connexin 43+/F-actin+ cells. It is also known that sympathetic and parasympathetic innervation create an autonomic plexus in the SAN that modulates heart rate and rhythm. However, the anatomical details of the interaction of this plexus with the pacemaker cell meshwork have yet to be described. The cytoarchitecture of SAN whole-mount preparations was examined by three-dimensional confocal laser scanning microscopy of triple immunolabeled with combinations of antibodies for HCN4, S100 calcium-binding protein B (S100B), glial fibrillary acidic protein (GFAP), choline acetyltransferase, or vesicular acetylcholine transporter, and tyrosine hydroxylase, and transmission electron microscopy. The SAN exhibited heterogeneous autonomic innervation, which was accompanied by a web of peripheral glial cells and a novel S100B+/GFAP- interstitial cell population, with a unique morphology and a distinct distribution pattern, creating complex interactions with other cell types in the node, particularly with HCN4-expressing cells. Transmission electron microscopy identified a similar population of interstitial cells as telocytes, which appeared to secrete vesicles toward pacemaker cells. Application of S100B to SAN preparations desynchronized Ca2þ signaling in HCN4-expressing cells and increased variability in SAN impulse rate and rhythm. The autonomic plexus, peripheral glial cell web, and a novel S100Bþ/GFAP- interstitial cell type embedded within the HCN4þ cell meshwork increase the structural and functional complexity of the SAN and provide a new regulatory pathway of rhythmogenesis.

Assessment of Fatigue Life for Corroded Prestressed Concrete Beams Subjected to High-Cycle Fatigue Loading

Millions of in-service concrete bridges around the world are exceeding their design life. Corrosion may lead to a sudden fracture of prestressing steels, and understanding the fatigue behavior of corroded prestressed concrete (PC) bridges is essential. Accordingly, an effective fatigue analytical model for corroded PC beams is needed. In this study, an experimental investigation of the fatigue behavior of corroded PC beams, was carried out. Thirteen PC beams had experienced acceleration corrosion before high-cycle fatigue testing. All beams failed due to fatigue fracture of the corroded tensile steel bars, and three-dimensional laser scanning results indicated that the fracture occurred at the minimum cross sections with a severe corrosion pit. A segmented linear analytical model to evaluate fatigue response and predict fatigue life was developed which considers fatigue irrecoverable plastic strain of concrete, stress concentration, and longitudinal variation in the cross-sectional areas of corroded steel bars. There is an acceptable agreement between the numerical and experimental results of corroded PC beams. The proposed model can reasonably predict the evolution of strains in concrete, corroded prestressing steel, and rebars in PC beams under high-cycle fatigue loading, thereby allowing fatigue life prediction. Further analysis studied the influence of degree of corrosion in prestressing wires/rebars, stress concentration and longitudinal variation in cross-sectional areas of corroded steel bars, load ranges, and partial prestressing ratios (PPRs). It was found that, to reasonably estimate the fatigue life of corroded PC beams, the influence of stress concentration must be considered with the proposed impact factor. A higher corrosion degree, load range, or PPR shortens the fatigue life of corroded PC beams.

Prediction of the skid-resistance deterioration in asphalt pavement based on peephole–LSTM neural network

ABSTRACT Poor pavement skid resistance contributes to frequent traffic accidents, with the asphalt surface rapidly deteriorating over time. Accurate prediction of skid resistance behavior is essential for road safety. This study introduces a pavement accelerated polishing system, collecting data from 11 stages using a British pendulum tester and a high-precision three-dimensional laser scanner. It develops a predictive model, FrictionNet-II, based on a peephole long-short time memory (peephole-LSTM) neural network. The model uses data from the first eight polishing stages as input and the last three as output, allowing for predictions of pavement skid resistance after 160,000, 180,000, and 200,000 cycles based on the friction deterioration curve of the initial stages (0 to 140,000 cycles). FrictionNet-II accurately forecasts skid resistance after 160,000, 180,000, and 200,000 cycles, achieving R2 values of 88%, 90%, and 90%, respectively. This research demonstrates the potential of deep learning in predicting asphalt pavement skid resistance, laying the foundation for intelligent pavement preservation and improved skid-resistance performance.

Experimental investigation on ex-vessel debris bed formation using low melting-point melt of binary metals

During severe accidents in a light water reactor, the core melt (corium) may relocate to the lower head and fail the reactor pressure vessel (RPV). The corium will be ejected to the reactor cavity upon the RPV failure and undergo melt coolant interactions (FCI) if the cavity is flooded with water. The FCI process does not only determines the characteristics of the resulting debris bed which are important to coolability, but also induces a steam explosion risk which may threaten containment integrity. The present study is concerned with characterization of debris bed formed from FCI of metal-rich corium failing into a deep water pool in the reactor cavity. Low melting-point metals Tin and Tin–Bismuth (20 kg) were employed as the simulant materials of metal-rich corium melt. Ten tests were carried out on the DEFOR-M test facility at KTH to investigate the effects of various parameters on debris bed formation, such as melt superheat, coolant subcooling, material. The melt jet fragmentation and fragments movement in the water pool as well as debris deposition on the pool floor were recorded by high-speed cameras. Melt sensors and weight sensors were installed to detect the period of melt jet discharge and the mass of forming debris bed. The porosity of debris bed was obtained through the debris bed volume measured by a three-dimensional laser scanner and the pore volume measured by water absorption. The final configuration of debris bed was also reconstructed through the laser scanner data, and the debris particles were sieved for their size distribution. The experimental results revealed the FCI phenomena and debris bed characteristics including configuration and porosity of debris bed as well as morphology and size distribution of debris particles under different melt superheats, coolant subcooling, materials.

The safety factor of a heterogeneous slope in an open-pit metal mine: A case study from the Tanjianshan gold mine

A landslide of the north open-pit (323N) and the stability and design optimization of the south open-pit (323S) slope in the 323 belts of the Tanjianshan Gold Mine were studied. On 14 September 2020, a large landslide occurred on the east side of 323N, which posed a severe threat to the safety production of the mine. To avoid a similar slide on the south open-pit in the 323S, the limit equilibrium method was used to estimate the stability of the final slope of the designed initially open-pit in the 323N. The results show that the location and scale of the landslide are in good agreement with the three-dimensional laser scanning data. The effectiveness of the limit equilibrium method in slope stability analysis of the Tanjianshan Gold Mine was validated. The stability of the final slope of the initial design of 323S was analyzed. The sensitivity of the safety factor of homogeneous slope and heterogeneous rock slope to the bench face angle (BFA) and the difference of landslide type were compared and studied. When the spatial geometric relationship of rock masses with different lithology is complex, the engineering analogy method is inapplicable to calculation of parameters such as the BFA of heterogeneous rock slope and overall slope angle of the open-pit. The slope safety factor should be checked, and the slope step parameters are warranted to be optimized. The safety and economic benefits of the slope can be improved.

Analysis of the Mechanisms Underpinning Rainstorm-Induced Landslides

The present study considers the damage mechanisms and the rainfall infiltration process responsible for landslide phenomena which originate from accumulation slopes. Accordingly, a physical test model is developed for different slopes and different rainfall conditions. Moreover, a three-dimensional laser scanner and a camera are used to monitor the slope erosion and the landslide dynamic evolution. Using this approach, the time variation curves of volumetric water content, pore water pressure, soil pressure, slope deformation, and damage are determined. The results show that under similar conditions, similar trends of the pore water pressure are achieved for different slopes and rainfall intensities.

Method for visualizing the shear process of rock joints using 3D laser scanning and 3D printing techniques

This study presents a visualized approach for tracking joint surface morphology. Three-dimensional laser scanning (3DLS) and 3D printing (3DP) techniques are adopted to record progressive failure during rock joint shearing. The 3DP resin is used to create transparent specimens to reproduce the surface morphology of a natural joint precisely. The freezing method is employed to enhance the mechanical properties of the 3DP specimens to reproduce the properties of hard rock more accurately. A video camera containing a charge-coupled device (CCD) camera is utilized to record the evolution of damaged area of joint surface during the direct shear test. The optimal shooting distance and shooting angle are recommended to be 800 mm and 40°, respectively. The images captured by the CCD camera are corrected to quantitatively describe the damaged area on the joint surface. Verification indicates that this method can accurately describe the total sheared areas at different shear stages. These findings may contribute to elucidating the shear behavior of rock joints.

Three-dimensional of lingual arch form and creation of templates in Iraqi normal occlusion.

To evaluate the lingual dental arch form types in class I canine and molar relationship based on scanning dental cast models using three-dimensional laser scan and to give a new lingual arch form pattern created on this classification to be used for clinical submission by studying three-dimensional virtual models of the normal occlusion samples. Maxillary and mandibular casts of 120 young adults (18-24 ± 1.84 years) have normal occlusion that was scanned using a 3Shape E1 laser scanner, and then, the data were analyzed using SPSS software; then, we used K-means cluster to classify the arch form into clusters depending on the measurement of 10 landmarks designated on the lingual surface of the teeth. Many dental arch patterns have been established for both the mandible and the maxilla. The minimum sizes were found in the females, and the biggest sizes were found in the male subjects, and three sets were well defined for each sex; three categories for each mandible and maxilla are as follows: narrow, mid, and broad. The lingual arch form can be classified into three groups based on posterior and anterior dimensions, so a template of the three arch forms has been exemplified.

Theoretical and practical bases of application of three-dimensional laser scanning technology in forensic construction and technical expertise

The article deals with the application of 3D laser scanning technologies in forensic construction and technical expertise, as well as the advantages of using this method. The analysis of the main types of laser scanning is carried out taking into account the size, complexity of the object and its technical features. Examples of effective use of 3D laser scanning in forensic construction and technical expertise are considered.

Application of Laser Scanning in Internal Surveying of Premises and Development of 3D Model of Building

Nowadays, along with the classical and experienced surveying methods, modern technologies are rapidly developing and entering into the economy. Laser scanning has many benefits and uses. Application of this technology results in a point cloud from which it is possible to create three-dimensional models which can represent topographic properties, structure dimensions, and spatial relationships. The aim of the research is to investigate the application of three-dimensional laser scanning in the internal surveying of premises and in the development of the 3D model buildings. The task of the research is to apply the application of laser rangefinder and ultrasonic rangefinder method in the scanning of a building that is characterized by complex architecture, an interior garden, many protrusions, and a special layout of windows and doors. The use of the Stonex X300 laser scanner and Stonex M6 laser rangefinder has been described as well. To achieve the goals and objectives of the research, laser telemetry and ultrasonic telemetry method, method of three-dimensional modeling, as well as analysis of scientific literature, mathematical calculation methods, and analysis of documents and factual materials have been used. As the result of the investigation 3D model of a building consisting of 47 individual point clouds was developed. The main conclusion is that three-dimensional modeling as a computer graphics method for the three-dimensional representation of any object or surface can be used.

Experimental investigation on the fracture surface features of heat-treated red sandstone containing fissure under constant amplitude low cycle impact using 3D digital reconstruction

Fractured rocks as typical engineering materials are commonly exposed to temperatures and dynamic perturbations. In this paper, constant amplitude low cycle (CALC) impact tests were carried out on red sandstone containing a single fissure (0°, 30°, 60° and 90°) after thermal treatment (25 °C, 200 °C, 400 °C, 600 °C and 800 °C) utilizing a modified split Hopkinson pressure bar (SHPB). Subsequently, the fracture surfaces of the failure specimens were digitally reconstructed based on point cloud data captured by a three-dimensional (3D) laser scanning. And scanning electron microscopy (SEM) was also employed as a complementary tool to study the fracture micromorphology. The fractal and rough features of fracture surfaces based on the box-counting method and image segmentation method were investigated, respectively. Meanwhile, four second-order statistics in the grayscale co-occurrence matrix (GLCM) of the digitized fracture surface after grayscale processing were calculated to describe the fracture surface texture. The best-fit multiple regression models between the fracture surface feature parameters and the interaction of temperatures and fissure angles were constructed and analyzed. Moreover, the relationships between the fracture surface features and the mechanical parameters as well as the intrinsic mechanisms were analyzed and discussed in detail. The results demonstrate that the fractal dimension (DC), joint roughness coefficient (JRC), maximum elevation difference (MD), roughness characterization factor (ω), and GLCM second-order statistics possess specific response patterns to the temperatures and fissure angles. Whether the sensitivity in portraying the fracture surface features to the interaction of temperatures and fissure angles or the reliability of the best-fit multiple regression models, the shadow method based on image segmentation behaves more promisingly. Furthermore, conspicuous correlations can be found between both the feature parameters including the GLCM second-order statistics and the failure strength, strain rate as well as life. The high temperature activates thermal activation mechanisms that alter the potential crack sources and pathways in the grain and rock skeleton, affecting the microscopic fracture face morphology. Finally, the maximum tensile stress at the edge of the prefabricated fissure might be responsible for the angle effect exhibited by the feature parameters.

Application of a modern laser technique to evaluate the performance of recycled railway ballast

The performance of railway track structure is influenced by the ballast shape properties including roundness, flatness, elongation, sphericity, angularity and surface texture. The challenge is how to accurately measure the irregular shapes of ballast materials and directly link them to performance. In this paper, a modern three-dimensional laser technique was used to determine shapes of freshly produced crushed ballast and recycled ballast sampled from the heavy-haul coal line in South Africa. The objective was to investigate the effect of ballast shapes on settlement (i.e. permanent deformation). All five ballast materials were scanned in the three-dimensional laser scanning system and the data collected was processed to reconstruct three-dimensional models of the ballast particles. The results obtained were used to develop a chart to classify ballast shapes and link these shapes physically with settlement determined from a triaxial testing programme. Based on the triaxial test results, new empirical models were developed to determine settlement on the route corridor of the heavy-haul coal line. It is anticipated that outcomes of this study would assist with quality assessments and railway ballast maintenance in the field.

High-speed penetration of cast Mg-6Gd-3Y-0.5Zr alloy: Experiments and modeling

Ballistic impact experiments are conducted on a cast Mg-6Gd-3Y-0.5Zr alloy using spherical projectiles under a wide range of impact velocities. Penetration processes are captured by high-speed camera. Postmortem target samples are characterized via three-dimensional laser scanning, metallographic microscopy, scanning electron microscopy and electron backscatter diffraction. Shear bands and twinning dominate the deformation of Mg-6Gd-3Y-0.5Zr near the crater, and texture changes due to compression caused by cavity expansion. For instance, a finite element model based on Johnson–Cook constitutive model and Mie–Grüneisen equation of state is established. Four dimensionless quantities related to craters and projectiles are defined. An analytical model based on dynamic cylindrical cavity expansion model is applied considering projectile deformation, and consistent well with experimental and simulated results over the entire incident velocity range.

Coral holobiont research needs spatial analyses at the microbial scale.

Coral holobiont research needs spatial analyses at the microbial scale.