High-resolution 3D Laser Research Articles

Accurate Prediction of Anthropometric Body Dimensions by 3D Optical Imaging Versus a High-Resolution 3D Laser Scanner

Accurate Prediction of Anthropometric Body Dimensions by 3D Optical Imaging Versus a High-Resolution 3D Laser Scanner

Thickness, Adhesion and Microscopic Analysis of the Surface Structure of Single-Layer and Multi-Layer Metakaolin-Based Geopolymer Coatings

This work is focused on creating coating layers made of a metakaolin-based geopolymer suspensions (GP)-formed Al matrix modified using H3PO4 acid with Al(OH)3 in isopropyl alcohol, named GP suspension I, and H3PO4 acid with nano Al2O3 in isopropyl alcohol, named GP suspension J. The selected GP suspensions were applied on aluminum and steel underlying substrates as single-layer coatings and multi-layer coatings, where multi-layer coatings included three and five layers that were polymerized by a curing process. Curing was divided into two types with every layer curing process and final layer curing process. For both GP suspensions I and J, the effect of the number of layers and the type of substrate on adhesion was investigated. The prepared samples on underlying substrates were characterized on the microscopy analysis including SEM for high-resolution images and 3D laser confocal microscopy (CLSM) for the 3D visualization of the coatings structure. Microscopy analysis showed structural defects such as porosity, cracks and peeling, which increase with a greater number of applied layers. However, these defects were only evident on a micro scale and did not seem to be fatal for the performance of the surface stability. The EDS mapping of the prepared layer showed inhomogeneity in the distribution of elements caused by the brush application. A grid test and thickness measurement were performed to complete the microscopy analysis. The grid test confirmed a very high adhesion of GP coatings on the aluminum substrate with a rating of one (only in one case was there a rating of two) and a lower adhesion on the steel substrate with the most frequent rating of three (in one case, there were ratings of two and one). The thickness measurement proved a noticeably thicker thickness of the prepared layer on the Fe substrate compared to the Al substrate by 20%–30% in the case of suspension I and by 70%–10% in the case of suspension J. The thickness of the layer also showed a dependence on the method of application and curing, as a thicker layer was always achieved when curing after the final layer of the GP suspension, compared to curing after each applied layer. The resulting single-layer and multi-layer thicknesses ranged from approx. 7 to 30 µm for suspension I and from approx. 3 to 11 µm for suspension J. A non-linear increase in thickness was also evident from the thickness measurement data.

Can a Hand-Held 3D Scanner Capture Temperature-Induced Strain of Mortar Samples? Comparison between Experimental Measurements and Numerical Simulations

The expected lifespan of cement-based materials, particularly concrete, is at least 50 years. Changes in the pore structure of the material need to be considered due to external influences and associated transport processes. The expansion behaviour of concrete and mortar during freeze–thaw attacks, combined with de-icing salt agents, is crucial for both internal and external damage. It is essential to determine and simulate the expansion behaviour of these materials in the laboratory, as well as detect the slow, long-term expansion in real structures. This study measures the expansion of mortar samples during freeze–thaw loading using a high-resolution hand-held 3D laser scanner. The specimens are prepared with fully or partially saturated pore structures through water storage or drying. During freeze–thaw experiments, the specimens are exposed to pure water or a 3% sodium chloride solution (NaCl). Results show contraction during freezing and subsequent expansion during thawing. Both test solutions exhibit similar expansion behaviour, with differences primarily due to saturation levels. Further investigations are required to explore the changing expansion behaviour caused by increasing microcracking resulting from continuous freeze–thaw cycles. A numerical analysis using a 3D coupled hygro-thermo-mechanical (HTM) model is conducted to examine the freeze–thaw behaviour of the mortar. The model accurately represents the freezing deformation during the freeze–thaw cycle.

Experimental investigation of a fissured rock with thermal storage potential subjected to descending amplitude low cycle impacts

As the advancement of deep earth energy engineering in the 21st century, the challenges imposed by dynamic loads and high temperatures will be increasingly regular. This paper studied the dynamic mechanical behaviors and fracture characteristics of defective red sandstone (single fissure inclination of 0°, 30°, 60°, and 90°) subjected to thermal treatments (25 °C, 200 °C, 400 °C, 600 °C, and 800 °C) under descending amplitude low cycle (DALC) impact loading. The experiments were conducted using a modified split Hopkinson pressure bar (SHPB) system, and the fracture surfaces of the failed specimens were characterized through the use of high-resolution 3D laser scanning to obtain point cloud data. Subsequently, the fractal, roughness, texture, and elevation features of fracture surfaces were analyzed using the boxing-counting method, grayscale co-occurrence matrix (GLCM), and elevation-based statistics. The scanning electron microscopy (SEM) was utilized to study the fracture micromorphology as well. Additionally, the mechanisms of damage and fracture evolution were discussed based on the results of X-ray diffractometry (XRD), synchronous thermal analysis (STA), discrete element method (DEM), and strain energy density theory. The results demonstrate that the peak stress and dynamic elastic modulus deteriorate with rising temperatures and increase with larger fissure angles. While the peak strain, strain rate, and peak stress increase factor (PIF) exhibit the opposite trend. The threshold values for the intensification of these events are 400 °C and 60°. The damage is dominated by tensile cracks, which transition to shear at 30° and 60° due to temperature dependence. Meanwhile, the fractal dimension (DC), joint roughness coefficient (JRC), second-order statistics of GLCM, and elevation eigenvalues have been modeled using multiple regression analysis to investigate their interaction with temperature and fissure angle. The best-fit models illustrate significant linear or non-linear correlations between the aforementioned parameters and the mechanical parameters. Furthermore, the magnitude and distribution pattern of thermal cracks, as well as the growth of shear fractures, are governed by the dehydration, thermal expansion, phase transition, plasticization, thermal fracture, and thermal decomposition. Finally, strain energy density theory manifests promising prospects for understanding and predicting DALC impact fracture patterns of specimens.

Application of Mobile Mapping System to a Cable-Stayed Bridge in Thailand.

Infrastructures must be inspected regularly to ensure serviceability and public safety. In the case of the Thailand expressway, 200 km of an elevated structure must be inspected once a year. Thailand expressway is an elevated reinforced concrete structure. Visual inspection for defects and structural movements such as excessive deflections, transverse movements, or settlements is a cumbersome process. Therefore, a mobile mapping 3D laser scanning (MLS) which is a high-resolution 3D laser scanner (Trimble MX-8) equipped on a vehicle, was introduced. Scanning was performed on live traffic on the expressway. From MLS, both the structure geometry and pavement point cloud data were obtained. A good agreement between elevations of the Rama XI bridge in Bangkok measured by point cloud data using MLS and by a real-time kinematic survey was obtained. The effect of mesh size on the output by MLS was investigated. It was found that a mesh size of 10 cm reduced the computational effort by 75% when compared to a mesh size of 5 cm. However, the International Roughness Index was reduced by 5%. International Roughness Index (IRI) estimated by MLS was close to the IRI values measured by the profilometer. However, a significant overestimation in the case of rutting depth was observed.

Laser-based finite element model reconstruction for structural mechanics

It is imperative to know the health condition of a structure during its service life. The development of laser scanning technology has created new opportunities to leverage high-resolution 3D laser scanning (3DLS) as a non-destructive evaluation tool for detailed geometrical information extracted for the creation of precise computational models. However, the workflow associated with this integration is indirect and presents challenges. The existing scan-to-model strategies use completely scanning data to generate a new finite element model (FEM), leading to excessive computational costs, especially if nonlinear analysis is required. In view of this, this study creates a pathway for a direct scan-to-model strategy suitable for translating condition data derived from a 3D laser scanning system into a FEM capable of describing the mechanical response of the component. Then, based on the scan-to-model strategy, a localized pathway to automatically identify the damaged parts and locally update the FEM is proposed. Instead of generating a new FEM of the damaged component, only the damaged parts are updated, which can reduce the computation cost. After that, the pathways were validated through laboratory-scale tensile testing using 3D Digital Image Correlation (3D-DIC), which enabled full-field deformation characterization and correlation with numerical model prediction. Results of this study provide the foundation of a computational framework for establishing the fundamental link between visually observable geometric and numerical models that engineers use to understand the performance of engineered systems.

Exploring 3D elastic-wave scattering at interfaces using high-resolution phased-array system

The elastic-wave scattering at interfaces, such as cracks, is essential for nondestructive inspections, and hence, understanding the phenomenon is crucial. However, the elastic-wave scattering at cracks is very complex in three dimensions since microscopic asperities of crack faces can be multiple scattering sources. We propose a method for exploring 3D elastic-wave scattering based on our previously developed high-resolution 3D phased-array system, the piezoelectric and laser ultrasonic system (PLUS). We describe the principle of PLUS, which combines a piezoelectric transmitter and a 2D mechanical scan of a laser Doppler vibrometer, enabling us to resolve a crack into a collection of scattring sources. Subsequently, we show how the 3D elastic-wave scattering in the vicinity of each response can be extracted. Here, we experimentally applied PLUS to a fatigue-crack specimen. We found that diverse 3D elastic-wave scattering occurred in a manner depending on the responses within the fatigue crack. This is significant because access to such information will be useful for optimizing inspection conditions, designing ultrasonic measurement systems, and characterizing cracks. More importantly, the described methodology is very general and can be applied to not only metals but also other materials such as composites, concrete, and rocks, leading to progress in many fields.

Acoustic wave coupling between optical fibers of different geometries.

In this study, we investigate coupling of acoustic guided waves from different types of input fibers, through a bonded coupler, to an optical fiber. These acoustic waves can then be detected with conventional fiber Bragg gratings (FBGs). The input waves are measured using a high-resolution 3D laser Doppler vibrometer, and the output waves in the optical fiber are measured using an FBG. We demonstrate that the wave coupling between two waveguides varies with the cross-sectional area and the modulus of elasticity of the fibers.

Study of Pavement Micro- and Macro-Texture Evolution Due to Traffic Polishing Using 3D Areal Parameters.

Pavement micro- and macro-texture have significant effects on roadway friction and driving safety. The influence of traffic polish on pavement texture has been investigated in many laboratory studies. This paper conducts field evaluation of pavement micro- and macro-texture under actual traffic polishing using three-dimensional (3D) areal parameters. A portable high-resolution 3D laser scanner measured pavement texture from a field site in 2018, 2019, and 2020. Then, the 3D texture data was decomposed to micro- and macro-texture using Fourier transform and Butterworth filter methods. Twenty 3D areal parameters from five categories, including height, spatial, hybrid, function, and feature parameters, were calculated to characterize pavement micro- and macro-texture. The results demonstrate that the 3D areal parameters provide an alternative to comprehensively characterize the evolution of pavement texture under traffic polish from different aspects.

Development of in vitro 3D brain models on laser fabricated scaffolds

In this work, we present the design and implementation of a 3D scaffold platform that supports and promotes intricate neuronal network development. 3D scaffolds were produced by two-photon polymerization (2PP), a high-resolution 3D laser microstructuring technology, using the biocompatible and non-degradable photopolymer. Human iPSC-derived neuronal networks have developed and interconnected in a 3D environment shaped by vertically stacked scaffold layers. The iPSC-derived neuronal progenitor cells could develop into cortical projection neurons (CNPs) of all six layers, different types of inhibitory neurons and glia. The network showed strong neuronal spontaneous activity that combined individual and collective signaling events. Our results highlight advanced microstructured 3D scaffolds as a reliable platform for 3D in vitro modelling of neuronal functions.

Erosion-inhibiting potential of a novel remineralising paste

The increasing prevalence of erosive tooth wear among children and young adults is an issue of growing concern, emphasising the need for improvement in the currently used preventive strategies. Our aim was to evaluate individual and synergistic effects of SnF2 and CPP-ACP pastes in inhibiting erosion at a nano-scale. Forty flat, polished enamel specimens were subjected to 10 erosion cycles, with each cycle comprising one-min erosion in citric acid (pH 3.0) and one-min exposure to human saliva. In each of the 3 experimental groups (n = 10 per group), a remineralising paste (10% CPP-ACP or 0.45% SnF2 (1,100 ppm F) or SnF2/CPP-ACP (combined 10% CPP-ACP and 0.45% SnF2)) was applied as a slurry in saliva between erosion cycles. No remineralising agent was used in control specimens (n = 10). Erosion was assessed by calculating erosion depth using a novel photolithographic technique combined with high-resolution 3D laser scanning microscopy from baseline to 1 min, 5 min and 10 min. A significant increase in erosion depth was detected in the control group as early as 1 min (69.4 nm) (P < 0.001), with the erosion depths being smaller for all three remineralising agents after 1 min (P ≤ 0.004). The overall trend of erosion depth reduction was SnF2/CPP-ACP > SnF2 > CPP-ACP > control. Application of SnF2-enriched CPP-ACP agent reduces dental erosion more than either SnF2 or CPP-ACP alone, offering a potentially more-effective preventive strategy to manage this condition.

High Friction Surface Treatment Deterioration Analysis and Characteristics Study

High friction surface treatment (HFST) is used to improve friction on curved roadways, especially on curves that have a history of wet pavement crashes. Observations on the long-term performance monitoring of HFST sections at the National Center for Asphalt Technology (NCAT) Test Track showed friction (skid number, SN) dropped significantly at the end of service life of HFST, creating unsafe driving conditions. There is no clear, observed friction deterioration trend to predict the friction drop when using friction performance measures like SN. Therefore, there is an urgent need to explore and develop supplementary HFST safety performance measures (such as aggregate loss) that can correlate to friction deterioration and provide predictable, cost-effective, and easily measurable results. The objectives of this paper are to (i) analyze the correlation between HFST aggregate loss percentage area and friction value using a dynamic friction tester (DFT), and (ii) study the characteristics of HFST deterioration associated with aggregate loss, at the NCAT Test Track and at selected HFST curve sites in Georgia (using 2D imaging and high-resolution 3D laser scanning). Results show a strong correlation between HFST aggregate loss percentage area and DFT friction coefficient. Where friction measurement is used as the primary safety performance measure, it is recommended that HFST aggregate loss be used as a supplementary performance measure for monitoring the HFST safety performance deterioration. Aggregate loss can be easily identified by characteristics such as color and texture change. Preliminary texture analyses of 3D HFST surface profiles show lower mean profile depth (MPD) and ridge-to-valley depth (RVD) texture indicators can also identify loss of aggregate spots on HFST surface.

Neural network-based prediction of sideway force coefficient for asphalt pavement using high-resolution 3D texture data

ABSTRACT The pavement friction has been recognised as a critical contributor to traffic safety and an important pavement functional characteristic. The sideway force coefficient routine investigation machine (SCRIM) has been used in many studies for pavement friction evaluation. However, this device is costly to purchase and run which limits its accessibility to many transportation agencies. This study explores an artificial neural network model to predict the sideway force coefficient (SFC) from SCRIM using pavement micro- and macro-texture information. On the selected field site, pavement texture was evaluated by a digital sand patch tester and a portable high-resolution 3D laser scanner, while pavement friction was measured using a SCRIM. The obtained high-resolution 3D texture data was decomposed into micro- and macro-textures via discrete Fourier transform and Butterworth filters. Then, height, feature, and hybrid texture parameters were calculated to characterise pavement 3D texture at the micro- and macro-levels. Next, the obtained pavement texture parameters were used to predict SFC through linear and neural network models. The neural network model, including pavement micro- and macro-texture parameters, shows better performance than other models and is adequate to predict SFC. Besides, pavement micro-texture shows more contribution to SFC than macro-texture.

In Vitro Development of Human iPSC-Derived Functional Neuronal Networks on Laser-Fabricated 3D Scaffolds.

Neural progenitor cells generated from human induced pluripotent stem cells (hiPSCs) are the forefront of ″brain-on-chip″ investigations. Viable and functional hiPSC-derived neuronal networks are shaping powerful in vitro models for evaluating the normal and abnormal formation of cortical circuits, understanding the underlying disease mechanisms, and investigating the response to drugs. They therefore represent a desirable instrument for both the scientific community and the pharmacological industry. However, culture conditions required for the full functional maturation of individual neurons and networks are still unidentified. It has been recognized that three-dimensional (3D) culture conditions can better emulate in vivo neuronal tissue development compared to 2D cultures and thus provide a more desirable in vitro approach. In this paper, we present the design and implementation of a 3D scaffold platform that supports and promotes intricate neuronal network development. 3D scaffolds were produced through direct laser writing by two-photon polymerization (2PP), a high-resolution 3D laser microstructuring technology, using the biocompatible and nondegradable photoreactive resin Dental LT Clear (DClear). Neurons developed and interconnected on a 3D environment shaped by vertically stacked scaffold layers. The developed networks could support different cell types. Starting at the day 50 of 3D culture, neuronal progenitor cells could develop into cortical projection neurons (CNPs) of all six layers, different types of inhibitory neurons, and glia. Additionally and in contrast to 2D conditions, 3D scaffolds supported the long-term culturing of neuronal networks over the course of 120 days. Network health and functionality were probed through calcium imaging, which revealed a strong spontaneous neuronal activity that combined individual and collective events. Taken together, our results highlight advanced microstructured 3D scaffolds as a reliable platform for the 3D in vitro modeling of neuronal functions.

An investigation on the correlation between the joint roughness coefficient (JRC) and joint roughness parameters

Correlation of the joint roughness coefficient (JRC) and various parameters for joint roughness evaluation was investigated in this study. A high-resolution 3D laser scanner was employed to precisely record roughness characteristics of 16 tensile fractured rock joints with different sizes. Direct shear tests were then conducted on rock joints and employing Barton’s equation, JRC for each joint is back-calculated. Joint profiles were retrieved from the captured 3D joint planes and roughness statistical parameters including Z2, SDi,Rp, and SF were calculated for each profile at 3 different sampling intervals (0.02 mm, 0.05 mm, and 0.1 mm). It was understood that Z2 and SF had the strongest correlation with JRC. Several equations were proposed for estimation of JRC using statistical parameters most of which yielded similar results to previous related research. Based on the findings of this study, all statistical parameters except SF experience a devaluation when sampling interval increases while SF value increases somewhat drastically with a raise in sampling interval. It was concluded that the sampling interval has a significant impact on all studied parameters and must be carefully chosen so further errors can be avoided.

Modelling Based on a Certified Level of Accuracy: The Case of the Solimene Façade

The advances in surveying techniques based on high resolution 3D laser scanners and photo shot data sets make it possible to measure the deviation between the numerical experimental model and the mathematical model. The former model is discontinuous but objectively defined on the bases of the precision of the instrument whereas the latter is continuous but abstract in its analogically idealized geometrical form. By sharing survey data it is possible to devise interoperable workflows which are useful in the design activities of architects and engineers. This paper discusses the convenience of sharing survey data to manage models and information presenting a case study of the facade of Paolo Soleri’s Solimene factory as a pilot procedure to organize a shared and interoperable workflow.

Single crystal diamond blazed diffraction gratings and Fresnel microlens arrays with improved optical performance by high-resolution 3D laser lithography and pattern transfer by dry etching

We present a method to fabricate high precision 3D micro-optical components in single crystal diamond, and we demonstrate and experimentally characterize Fresnel microlens arrays and blazed diffraction gratings. The fabrication process is based on high-resolution 3D dip-in laser lithography and pattern transfer by chlorine-based reactive ion etching with a low diamond:photoresist selectivity (1:15) to obtain smooth etched surfaces with Ra < 2 nm. The fabricated microlenses have a focal length that deviates by 4% from the target value, while the blazed diffraction gratings have a maximum relative efficiency of 66% in the first order.

Layered compressive sensing reconstruction for non-scanning three-dimensional laser imaging

ABSTRACTAs an active remote-sensing technique, three-dimensional (3D) laser radar enables accurate target detection and identification. However, the resolution of obtained image is limited by the integrated level of the sensor array. In this article, we propose a layered compressive sensing reconstruction method for high-resolution 3D laser imaging. The range profile is first reconstructed by applying a designed range observation matrix to the original sampling data. According to the distribution of range values in the reconstructed range profile, the original sampling data are divided into several layers and the corresponding intensity images are reconstructed by different algorithms. The global intensity image is generated by the reconstructed intensity images with different range compensation coefficients. In our simulations based on real data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model Version 2 (ASTER GDEM V2) and Landsat-8 Operational Land Imager (OLI), the proposed method realised 3D laser imaging for complex landforms with a pixel resolution of , and reached a satisfactory performance for reconstructions of the range profile (peak signal-to-noise ratio (PSNR) = 33.08 dB, feature similarity (FSIM) = 0.9450) and the intensity image (PSNR = 20.63 dB, FSIM = 0.8893) with a subrate of 0.25.

Numerical simulations of cross wind effects on cyclist aerodynamic resistance

Introduction : In outdoor cycling, cross wind can affect the race strategy and the final results. Ad-hoc strategies, like echelons and Belgian tourniquet formations, are indeed adopted by cyclists to reduce wind effects and aerodynamic drag. Forces and moments generated by cross winds have been often studied for isolated wheels [1,2] and for an entire isolated cyclist [3-5]. However, to the best of our knowledge, the impact of cross wind on a couple of cyclists has not yet been investigated. In this study, Computational Fluid Dynamics (CFD) simulations are used to evaluate the effect of cross wind on the aerodynamic resistance of a couple of cyclists in two different configurations: (1) when the trailing cyclist is placed in line with the leading cyclist (Fig. 1a) and (2) when both cyclists are staggered (Fig. 1b). To compare the results, additional simulations have been performed for a single cyclist. Moreover, the impact of the upstream turbulence intensity is investigated. CFD simulation: The cyclist geometry used in these simulations has been obtained by means of high resolution 3D laser scanning of elite cyclists. Further information is provided in Refs. (Defraeye, Blocken, Koninckx, Hespel, & Carmeliet, 2010) and (Blocken, Defraeye, Koninckx, Carmeliet, & Hespel, 2013). The computational grids consist of prismatic cells in the boundary layer region near the cyclist body while tetrahedral cells are adopted in the rest of the domain using proper growth factors. The total number of cells is about 8.3 M and 14.0 M, for the single and drafting cyclists, respectively. The simulations are performed using the commercial CFD code ANSYS/Fluent 15.0. The 3D steady Reynolds- Averaged Navier-Stokes (RANS) equations are solved in combination with the standard k- Iµ turbulence model with low Reynolds number modelling based on the one-equation Wolfshtein model. This choice was made since a good agreement with wind tunnel tests was achieved in a previous validation study for the case of zero yaw angle (Blocken, Defraeye, Koninckx, Carmeliet, & Hespel, 2013). The distance from the centre point of the wall adjacent cells to the cyclist body is about 30 I¼m corresponding to an average y* value of about 1. The simulations are performed for yaw angles between 0° and 45° in 5° intervals. Results: the results show that the drag of the leading cyclist is affected by the position of the trailing cyclist only at low yaw angles ( I¸ < 15 degrees). In this case, the drag area coefficient, C d A, is reduced by about 2.5% (not shown in the figures). The drag of the trailing cyclist however is highly influenced by his position with respect to that of the leading cyclist (Fig. 2). When the yaw angle is less than 15° the in line configuration is still advantageous while for larger angles the staggered configuration shows the best behavior both in terms of drag area coefficient and side force area coefficient, C s A. In the case of a single cyclist, a reduction of the drag area is obtained as the yaw angle increases. Conversely the side force area coefficient is increasing almost linearly with larger yaw angles. However the dimensional drag is almost constant until an angle of around 25°, while after it slightly increases. In future studies other configurations will be analyzed and bicycles will be included in the models.

Measuring Usewear on Black Gloss Pottery from Rome through 3D Surface Analysis

This project involves the high-resolution 3D laser scanning of a cache of Italian black gloss pottery from the Capitoline Museums in Rome. Our aim is to examine in detail the minute traces of production and use of these vessels and to produce a digital record of their form. We have experimented with several scanning devices in order to determine the optimal methods for capturing abrasions on pottery and are developing digital methods for surface analysis. The purpose of the analysis is to consider how black gloss vessels from ritual contexts (tomb and sanctuary deposits) may have been used before they were deposited and to refine our understanding of vessel production methods.