3D Laser Research Articles

High Precision Pose Estimation for Uncooperative Targets Based on Monocular Vision and 1D Laser Fusion

High Precision Pose Estimation for Uncooperative Targets Based on Monocular Vision and 1D Laser Fusion

Hydrogen susceptibility of Al 5083 under ultra-high strain rate ballistic loading

Abstract The effect of hydrogen on the ballistic performance of aluminum (Al) 5083H131 was examined both experimentally and numerically in this study. Ballistics tests were conducted at a 30° obliquity in accordance with the ballistic test standard MIL-DTL-46027 K. The strike velocities of projectiles were ranged from 240 m s−1 to 500 m s−1 level in the room temperature. Electrochemical hydrogen charging method was utilized to introduce hydrogen into material. Chemical composition of material was analyzed using energy dispersive X-ray (EDX) analysis. Instant camera pictures were captured using high-speed camera to compare H-uncharged and H-charged specimen ballistics tests. The volume loss in partially penetrated specimens were assessed using the 3D laser scanning method. Microstructural examinations were conducted utilizing scanning electron microscopy (SEM). It was observed that with the increased deformation rate, the dominance of the HEDE mechanism over HELP became evident. Furthermore, the experimental findings were corroborated through numerical methods employing finite element analysis (FEM) along with the Johnson–Cook plasticity model and failure criteria. Inverse optimization technique was employed to implement and fine-tune the Johnson–Cook parameters for H-charged conditions. Upon comparing the experimental and numerical outcomes, a high degree of consistency was observed, indicating the effective performance of the model.

Large-Area Perovskite Nanocrystal Metasurfaces for Direction-Tunable Lasing.

Perovskite nanocrystals (PNCs) are attractive emissive materials for developing compact lasers. However, manipulation of PNC laser directionality has been difficult, which limits their usage in photonic devices that require on-demand tunability. Here we demonstrate PNC metasurface lasers with engineered emission angles. We fabricated millimeter-scale CsPbBr3 PNC metasurfaces using an all-solution-processing technique based on soft nanoimprinting lithography. By designing band-edge photonic modes at the high-symmetry X point of the reciprocal lattice, we achieved four linearly polarized lasing beams along a polar angle of ∼30° under optical pumping. The device architecture further allows tuning of the lasing emission angles to 0° and ∼50°, respectively, by adjusting the PNC thickness to shift other high-symmetry points (Γ and M) to the PNC emission wavelength range. Our laser design strategies offer prospects for applications in directional optical antennas and detectors, 3D laser projection displays, and multichannel visible light communication.

Multi-Technique Approach for the Sustainable Characterisation and the Digital Documentation of Painted Surfaces in the Hypogeum Environment of the Priscilla Catacombs in Rome

The purpose of this paper is to identify an efficient, sustainable, and “green” approach to address the challenges of the preservation of hypogeum heritage, focusing on the problem of moisture, a recurring cause of degradation in porous materials, especially in catacombs. Conventional and novel technologies have been used to address this issue with a completely non-destructive approach. The article provides a multidisciplinary investigation making use of advanced technologies and analysis to quantify the extent and distribution of water infiltration in masonry before damage starts to be visible or irreversibly causes damage. Four different technologies, namely Portable Nuclear Magnetic Resonance (NMR), Audio Frequency–Acoustic Imaging (AF–AI), Laser-Induced Fluorescence (LIF), Infrared Thermography (IRT), and 3D Laser Scanning (RGB-ITR), were applied in the Priscilla catacombs in Rome (Italy). These imaging techniques allow the characterisation of the deterioration of painted surfaces within the delicate environment of the Greek chapel in the Priscilla catacombs. The resulting high-detailed 3D coloured model allowed for easily referencing the data collected by the other techniques aimed also at the study of the potential presence of salt efflorescence and/or microorganisms. The results supply an efficient and sustainable tool aimed at cultural heritage conservation but also at the creation of digital documentation obtained with green methodologies for a wider sharing, ensuring its preservation for future generations.

Композитные электроды на основе Li3V2(PO4)3, Li4Ti5O12 и углеродных нанотрубок : влияние состава, толщины и морфологии поверхности на электрохимические свойства

The influence of the composition, the thickness and the surface morphology of Li3V2(PO4)3 or Li4Ti5O12 based electrode composites with carbon nanomaterial and polyvinylidene fluoride on their electrochemical performance was examined. The thickness and the surface morphology of the electrodes were jointly controlled by rolling with different gaps and monitored using 3D laser microscopy and scanning electron microscopy. Increasing carbon nanomaterial content, the increase in the specific capacity of the electrode due to the non-Faradic component was observed up to the values of the specific capacity seemingly exceeding the theoretical capabilities of Li3V2(PO4)3 or Li4Ti5O12. When rolling the electrode with decreasing gap, we observed that Li3V2(PO4)3-based electrode composites improved their performance in terms of initial specific capacity and resistance to high current loads. As for Li4Ti5O12-based composites we observed the extremum. We concluded that not only the contact of Li4Ti5O12 or Li3V2(PO4)3 with electrolyte, but the three-phase contact of Li4Ti5O12 or Li3V2(PO4)3 with carbon nanomaterial particles and electrolyte as well was important for the electrochemical activity of electrode composites.

Automatic Measurement of Seed Geometric Parameters Using a Handheld Scanner.

Seed geometric parameters are important in yielding trait scorers, quantitative trait loci, and species recognition and classification. A novel method for automatic measurement of three-dimensional seed phenotypes is proposed. First, a handheld three-dimensional (3D) laser scanner is employed to obtain the seed point cloud data in batches. Second, a novel point cloud-based phenotyping method is proposed to obtain a single-seed 3D model and extract 33 phenotypes. It is connected by an automatic pipeline, including single-seed segmentation, pose normalization, point cloud completion by an ellipse fitting method, Poisson surface reconstruction, and automatic trait estimation. Finally, two statistical models (one using 11 size-related phenotypes and the other using 22 shape-related phenotypes) based on the principal component analysis method are built. A total of 3400 samples of eight kinds of seeds with different geometrical shapes are tested. Experiments show: (1) a single-seed 3D model can be automatically obtained with 0.017 mm point cloud completion error; (2) 33 phenotypes can be automatically extracted with high correlation compared with manual measurements (correlation coefficient (R2) above 0.9981 for size-related phenotypes and R2 above 0.8421 for shape-related phenotypes); and (3) two statistical models are successfully built to achieve seed shape description and quantification.

A parametric approach for creating finite element models from point clouds for steel superstructure components in steel girder bridges

Finite element (FE) analysis is widely used to evaluate the conditions of existing bridges. However, the creation of high-fidelity FE models (FEM) for existing bridges is often a challenging task. In view of the ability of 3D laser scanning to capture detailed geometrical information, this study proposes a direct scan-to-FEM strategy specifically for steel bridge superstructure and hence to facilitate the creation of high-fidelity FE models for existing steel girder bridges. Parametric representations are proposed to address partial occlusions in the point clouds as well as to reinforce the connectivity and alignment between the superstructure elements. Mesh generation algorithms are developed to automatically convert the parametric representations into all-hexahedron FE mesh assembly that can be used directly for FE analysis without any mesh verification or editing. Experimental validations are carried out to evaluate the effectiveness of proposed method in term of both mesh quality and analysis accuracy.

Advancements in Metal Processing Additive Technologies: Selective Laser Melting (SLM)

Nowadays, the use of metal processing additive technologies is a rapidly growing field in the manufacturing industry. These technologies, such as metal 3D printing (also known as additive manufacturing) and laser cladding, allow for the production of complex geometries and intricate designs that would be impossible with traditional manufacturing methods. They also offer the ability to create parts with customized properties, such as improved strength, wear resistance, and corrosion resistance. In other words, these technologies have the potential to revolutionize the way we design and produce products, reducing costs and increasing efficiency to improve product quality and functionality. One of the significant advantages of these metal processing additive technologies is a reduction in waste and environmental impact. However, there are also some challenges associated with these technologies. One of the main challenges is the cost of equipment and materials, which can be prohibitively expensive for small businesses and individuals. Additionally, the quality of parts produced with these technologies can be affected by factors such as printing speed, temperature, and post-processing methods. This review article aims to contribute to a deep understanding of the processing, properties, and applications of ferrous and non-ferrous alloys in the context of SLM to assist readers in obtaining high-quality AM components. Simultaneously, it emphasizes the importance of further research, optimization, and cost-effective approaches to promote the broader adoption of SLM technology in the industry.

Loss of normal facial asymmetry in schizophrenia and bipolar disorder: Implications for development of brain asymmetry in psychotic illness

Development of the craniofacies occurs in embryological intimacy with development of the brain and both show normal left-right asymmetries. While facial dysmorphology occurs to excess in psychotic illness, facial asymmetry has yet to be investigated as a putative index of brain asymmetry. Ninety-three subjects (49 controls, 22 schizophrenia, 22 bipolar disorder) received 3D laser surface imaging of the face. On geometric morphometric analysis with (x, y, z) visualisations of statistical models for facial asymmetries, in controls the upper face and periorbital region, which share embryological intimacy with the forebrain, showed marked asymmetries. Their geometry included: along the x-axis, rightward asymmetry in its dorsal-medial aspects and leftward asymmetry in its ventral-lateral aspects; along the z-axis, anterior protrusion in its right ventral-lateral aspect. In both schizophrenia and bipolar disorder these normal facial asymmetries were diminished, with residual retention of asymmetries in bipolar disorder. This geometry of normal facial asymmetries shows commonalities with that of normal frontal lobe asymmetries. These findings indicate a trans-diagnostic process that involves loss of facial asymmetries in both schizophrenia and bipolar disorder. Embryologically, they implicate loss of face-brain asymmetries across gestational weeks 7–14 in processes that involve genes previously associated with risk for schizophrenia.

Site-Selective Biofunctionalization of 3D Microstructures Via Direct Ink Writing.

Two-photon lithography has revolutionized multi-photon 3D laser printing, enabling precise fabrication of micro- and nanoscale structures. Despite many advancements, challenges still persist, particularly in biofunctionalization of 3D microstructures. This study introduces a novel approach combining two-photon lithography with scanning probe lithography for post-functionalization of 3D microstructures overcoming limitations in achieving spatially controlled biomolecule distribution. The method utilizes a diverse range of biomolecule inks, including phospholipids, and two different proteins, introducing high spatial resolution and distinct functionalization on separate areas of the same microstructure. The surfaces of 3D microstructures are treated using bovine serum albumin and/or 3-(Glycidyloxypropyl)trimethoxysilane (GPTMS) to enhance ink retention. The study further demonstrates different strategies to create binding sites for cells by integrating different biomolecules, showcasing the potential for customized 3D cell microenvironments. Specific cell adhesion onto functionalized 3D microscaffolds is demonstrated, which paves the way for diverse applications in tissue engineering, biointerfacing with electronic devices and biomimetic modeling.

Holographic multi-photon 3D laser nanoprinting – at the speed of light: opinion

In this opinion article, we discuss the possibility of printing three-dimensional macroscopic architectures with nanometer feature size by irradiating a light-sensitive ink with a single, spatiotemporally shaped, short laser pulse. We argue that the peak print rate of this approach may reach 1020-1021 voxels s-1, surpassing the present state-of-the-art of about 108 voxels s-1 by a very large margin.

Automated recognition and rebar dimensional assessment of prefabricated bridge components from low-cost 3D laser scanner

Dimension quality inspections for rebar spacing and length of prefabricated bridge components are critical for subsequent efficient assembly on-site. Currently, the traditional manual inspection method is time-consuming, labor-intensive, and error-prone. The existing commercial 3D LiDAR-based methods are difficult in making balances between inspection cost, efficiency, and accuracy. Thus, the automated recognition and segmentation method of 3D point clouds acquired by a self-developed low-cost LiDAR is proposed to evaluate the rebar spacing and length of bridge prefabricated components. Due to the high-cost commercial 3D laser scanner, a spinning 2D LiDAR-based low-cost 3D laser scanner device and geometric calibration model were developed to acquire the 3D spatial point cloud. Then, two-stage automated point cloud segmentation framework is proposed with coarse extraction of the point cloud in the interest region and fine recognition of point cloud using machine learning methods, including plane segmentation and circle fitting employing random sample consensus (RANSAC) algorithm, and rebars segmentation utilizing Gaussian mixture model (GMM) and density-based spatial clustering of applications with noise (DBSCAN) algorithm. The proposed system was evaluated in two prefabricated concrete columns and shows the potential for improving the quality inspection efficiency and accuracy.

Critical physics-informed fatigue life prediction of laser 3D printed AlSi10Mg alloys with mass internal defects

The significant scatter in high cycle fatigue life of additively manufactured metallic components presents an increasing challenge to structural integrity. This fatigue life variation is radically attributed to the differences in physical features of critical defects that lead to crack initiation. To address this issue, this paper proposes an integrated framework for identifying critical defects and predicting fatigue life using physics-informed machine learning, with a focus on the impact of 3D defect features. By employing X-ray tomography, high cycle fatigue tests, and fractography analyses on post-mortem specimens, a dataset associated with mass internal defects is first built up to correlate the spatial geometric features of critical defects with fatigue life. A kernel support vector machine is then used to formulate a critical defect identification model, aimed at identifying critical defects among numerous defects by evaluating their geometric attributes. Finally, a fatigue life prediction model is developed using a physics-informed neural network, which incorporates the influence of defect geometry on fatigue life as physical constraints in the loss function. The integrated framework demonstrates that fatigue life predictions from identified critical defects in each specimen exhibit small deviations, with the average prediction falling within twice the error bands. This study is expected to provide a valuable reference for fatigue assessment of additively manufactured components through sequential critical defect identification and fatigue life prediction.

3D oscillation-assisted laser beam cutting with time-synchronized process monitoring

A current subject of research is to optimize the laser cutting process in terms of process efficiency and cut edge quality, especially in thick sheet metal cutting. One approach is to influence the energy distribution in the cut kerf using various beam shaping options, including dynamic beam oscillation. The challenge lies in the fact that the oscillation parameters of beam shaping, which are added to the conventional laser cutting process, create an infinite number of new parameter combinations. For the first time, a complete system has been set up at the IWS in cooperation with the CMA with the aid of the process monitoring options. This system is intended to help provide deeper insights into the processes taking place in the cutting zone and thus contribute to an expanded understanding of the process. First experiments were carried out to investigate the influence of the 3D beam oscillations on the cut quality and cutting speed.

Stability of hot-finished and cold-formed steel hollow section columns: A comparative study

A comparative study into the buckling behaviour of hot-finished and cold-formed steel hollow section members subjected to axial compression is presented in this paper. The main differences between hot-finished and cold-formed hollow sections are initially discussed. An experimental programme conducted to investigate the local, global and local-global interactive buckling of hollow section columns is then described. Three S355 normalised hot-finished and three S355/S420 (dual certified) cold-formed profiles, covering circular, square and rectangular hollow sections (CHS, SHS and RHS respectively), were studied. The stress-strain characteristics of the examined materials were obtained through tensile coupon tests. 3D laser scanning was utilised to determine the distribution of geometric imperfections in selected SHS test specimens and a consistent approach to characterise different forms of geometric imperfections from the scan data is put forward. A stub column test was carried out on each cross-section to examine its local buckling behaviour, and a series of long column tests were performed on all test profiles. In total, 21 tensile coupon tests, six stub column tests and 40 long column tests were conducted in this programme. Finite element models were also developed, validated and used for parametric studies to generate supplementary numerical datasets. The obtained test and numerical data, along with the existing experimental results collected from the literature, were used to evaluate the accuracy and reliability of the Eurocode 3 (EC3) stability design provisions for hot-finished and cold-formed hollow section columns; aspects requiring improvements are highlighted to guide future studies.

Geometrical morphology and deformation measurement of long-span suspension bridge based on terrestrial laser scanning

Long-span suspension bridges necessitate deformation measurements for proper evaluation and upkeep. However, conventional approaches are unable to collect continuous spatial deformation data, which severely restricts their application in structural research. This paper presents a reliable and efficient method for measuring the deformation of suspension bridges using 3D laser scanning, including planning the scanning route, preprocessing the point cloud data, and extracting the deformation indicators. The method plans the scanning route based on experience and basic path planning principles to achieve both efficiency and precision, preprocesses the point cloud data by 3-stage denoising and curvature-based downsampling to preserve valuable point data better, and then proposes an extraction procedure for different types of deformation indicators. A field test on a typical long-span suspension highway bridge is performed, and the data processing and results extraction details are introduced. The accuracy and consistency of measurement results are discussed to verify the reliability of the proposed approach. The verified data provides useful information for the evaluation and maintenance of the bridge.

R–C–C fusion classifier for automatic damage detection of heritage building using 3D laser scanning

R–C–C fusion classifier for automatic damage detection of heritage building using 3D laser scanning

Tantalum granules with hierarchical pore structure for bone regeneration: Porous tantalum granules repair bone

Tantalum (Ta) has good potential for bone tissue engineering due to its excellent corrosion resistance and biocompatibility. However, the customization of Ta-based bone repair materials for irregularly shaped bone defects has been challenging due to their high melting point and hardness. In this work, porous tantalum granules (PTaG) were developed for the first time to repair irregularly shaped bone defects, inspired by the natural phenomenon of sand flow. PTaG were designed as a hierarchical porous structure to regulate the mechanical properties and provide a favorable space for inward growth of cells and tissues. Commercial porous titanium granules (PTiG) and Bio-Oss were used as positive controls to explore the potential of PTaG as bone substitute. The morphology, three-dimensional structure, composition, and mechanical properties of PTaG and PTiG were evaluated by SEM, X-Ray 3D imaging system, 3D laser confocal microscope, EDS, XRD, XPS, and nanoindentation. In vitro, cell compatibility and mineralization ability were evaluated for both materials. Furthermore, PTaG, PTiG, and Bio-Oss were filled in the rabbit femoral defect, and micro-CT and histological analysis were performed after 8 weeks. The results showed that the PTaG had the best bone healing effect due to the hierarchical porous structure, excellent three-dimensional connectivity and chemical stability, suitable mechanical properties and surface roughness, good biocompatibility and mineralization osteogenic activity. This work indicates that PTaG may have a positive potential for filling and repairing irregularly shaped bone defects.

LiDAR and CAD Reconstruction of Queen's University Ontario Hall

The emergence of highly accurate LiDAR (Light Detection and Ranging) technology has opened new avenues for engaging with and understanding cultural heritage sites. How do we convert buildings like Ontario Hall into editable 3D models to engage various stakeholders in a campus setting? This initiative developed from the goal of MobArch (Queen's Mobile Laboratory for the study of Architecture and the Built Environment) to use non-invasive visualization technologies to understand the social, developmental, and environmental impacts upon our built environment and architectural past. Current initiatives involving LiDAR for heritage conservation investigate hidden aspects of sites or address structural disrepair. The Ontario Hall project uniquely documents the state of a heritage building before structural concerns arise. This project creates an accurate digital record of Ontario Hall for future infrastructure initiatives and cultural preservation. In addition, this project tests the limits of LiDAR with 3D reconstruction in CAD (Computer Aided Design) software. This project used the Leica RTC360 3D Laser Scanner to create over 300 scans with a point cloud density of 6mm. The resulting cloud was optimized using Leica Cyclone Register 360 Plus software and was imported to Sketch Up where a 3D model was manually reconstructed based on the cloud data. The result of this project is a SKP file containing the 3D model, and the point cloud. The cloud is a highly accurate resource for future infrastructure projects. The 3D model contains room volumes, windows, staircases, and external architectural elements in a more edit-friendly software environment allowing diverse stakeholders to creatively reimagine Ontario Hall. The model can be integrated into archives, websites, games, and VR. Heritage architecture can contribute to the marketing appeal and visual identity of Queen’s. Moreover, awareness of community heritage improves social wellbeing and addresses the need to connect with our built history.

Corrosion behaviour of 110SS steel in hydrochloric acid and blended acid system at 200°C

The influence of organic acids (formic acid, acetic acid) on the corrosion behaviour of 110SS steel, a hydrogen sulphide corrosion resistant alloy steel, in hydrochloric (HCl) acid environments was studied. The corrosion rates of 110SS steels in HCl acid and blended acid were measured using the high-temperature and high-pressure corrosion tester. Scanning electron microscopy was utilised to observe the morphology of corrosion products on steel samples corroded by different acid systems, and the energy dispersive X-ray spectrometer was used to analyse the elemental composition of the corrosion products. The corrosion morphology was observed using a 3D laser scanner. The results indicated that the corrosion rate of 110SS steel in HCl acid at 200 °C was an exponential function of HCl concentration. Reducing the HCl concentration significantly decreased the corrosion rate of 110SS steel. Organic acids and corrosion inhibitors synergistically reduced the corrosion of 110SS steel in HCl acid. Adding 3 wt.% organic acid to the 15 wt.% HCl acid system further reduced the corrosion rate, with a more pronounced effect observed in the HCl–formic acid system compared to the HCl–acetic acid system. Organic acids chemically adsorbed onto the steel surface and decomposed to produce CO, which hindered the attack of hydrogen ions on the metal. The added corrosion inhibitor and intensifier Sb2O3 resulted in the formation of a compact adsorption film on the steel surface, further inhibiting corrosion. The optimal mass ratio of HCl acid to organic acid was found to be 15% to 3%.